Tuesday, December 21, 2010

The Phase Inverter Tube

The least understood tube in your vintage harp amp is the phase inverter. What the heck does it do?

In amps with two or more power tubes the phase inverter (PI) splits the music – after the preamp gain and tone stack EQ – into two out-of-phase signals. Each of your pairs of power tubes gets one of the signals to each tube, so that one tube pushes the sound and the other pulls it. If you have a master volume amp there is another gain stage after the phase inverter, but that is a different topic.

Amps with only one power tube don’t need a phase inverter. One of the main differences you hear between single ended amps and Class AB amps (with multiple power tubes) is the phase inverter. Stick with me here while I explain.

The common theory you hear spouted over and over by harp players is that we want to reduce the preamp gain in our amps so that we get to that sweet spot of power tube distortion before we hit the feedback threshold. Heck, I used the believe that myself, but I've come to learn that it means a lot more in small single ended amps.

In Class AB harp amps the power tubes are almost never driven hard enough to distort much. What you hear is the phase inverter breaking up! The power tubes just amplify that and pass it along. It can be a very sweet tone with a nice organic breakup.

The phase inverter circuit is not a gain stage, so the difference in amplitude you hear from a 12AX7, say, to a 12AU7 is not as great in the PI socket as it would be in the preamp socket. The goal in the choice of PI tube is no so much to quiet the amp down as it is to get a nice warm dynamic distortion when you hit the amp hard.

In general, my advice is to leave the phase inverter tube alone. Many amp makers now use all 12AX7 tubes in the preamp section (first and second gain stages and PI tube) to keep things simple and cheap. Older Fender amps used a 12AT7 as the PI. (Note: Never use a 12AT7 tube in any circuit for which it was not specifically designed. The AT7 is a terrible tone generator and very different from other tubes in the 12A?7 family.)

But, you CAN improve the tone of your amp by plugging in a 5751 in the PI socket. As you may know, this is my favorite input tube for harp amps. It is an industrial grade 12AX7 with slightly less gain and a warmer tone. Going all the way to a low-gain 12AU7 will give you more clean headroom, which is not really what you want in the phase inverter.

Or, you can throw out everything you just read and try it yourself. The phase inverter does not have to be biased or anything like that, so this is pretty much plug ‘n’ play. The PI tube is usually the small tube closest to the bigger power tubes. In a Fender Blues Junior, for example, it is the third small tube. Start counting at the tube closest to where you plug in your mic.

I’d encourage you to try the 12DW7 trick as well: very interesting results.

Remember to turn your amp off when swapping tubes and BE CAREFUL! Getting zapped can ruin your day. But understanding the role of the phase inverter tube in your vintage-style harp amp can help you get where you want to be tone-wise.

NOTE: Coming up soon I will have a video tone comparison of three different input tubes in the VHT Special 6 amp: The stock 12AX7, an NOS JAN Philips 5751, and an NOS 5965 tube.

Tuesday, December 14, 2010

Feedback and the Rectifiers

[Hmmmm. That would be a great name for a band.]

A reader emailed me to ask if it is true that changing to a copper plug-in solid state rectifier “will get you more power without feedback.”

The short answer is, No.

Let’s review feedback for a moment: We all know it well. When your amp starts to howl the very first thing you do is turn down either your amp or your mic. In other words, you reduce the amplitude of your entire system: harp, mic, and amp.

Also, we all know that if we crank up the treble on our amp it is more likely to start howling feedback, so we usually have the treble set relatively low.

Swapping your tube rectifier for a copper recto of the same value will result in a slightly increased B+ voltage and a reduction in vintage sag tone, which gives the perception of a tighter, more present sound. Does it make your amp truly louder? Maybe very slightly louder, but it would be hard to hear.

Will it reduce feedback? How could it? All the remedies we know of for feedback involve reduced amplitude and/or EQ filters. The rectifier does neither. The claim is bogus.

Review: Dan Treanor – My Blues Diary

Dan Treanor’s latest album is a tour de force; a musical roadmap of Dan’s blues journey from 1997 to the present. Yet each cut shares a stylistic and thematic key with the others. This is truly the blues diary of the last 14 years from a man steeped in blues music, and blues harp in particular.

The talent on the album is impressive. Darryl Lee sings most of the cuts with an understated passion and brief moments of sobbing power. It is a unique and effective blues voice. People I know on the album include session man Rich Reno – a great slide guitarist – and my bandmate Charles Billiris. Outstanding bluesman Randall Dubis also makes an appearance on ‘Blue Bossa,’ the 6th track. The entire roster is impressive.

But this is Dan Treanor’s baby and you can tell he loves it. Dan is known mostly for his brilliant harp playing and it is on good display here. His teasing, lilting harp lines on Sonny Boy’s “Nine Below Zero” are beautiful. His tone on the Chicago-style “Love Me With A Feeling” is worthy of Maxwell Street. Dan is at his best in minor blues with a Latin beat, and there are a couple of those gems on the CD. Lonesome Railroad Track, 3 O’Clock in the Morning, Stoop Down Baby; they all kill. My band performed the song “Cut With Dynamite” at the Colorado Blues Society IBC Finals with Dan sitting in. All thirteen tracks are keepers.

The album is well produced. The sound is warm and personal across all the cuts. Vocals are vibrant and detailed. I thought the opening to Mean Woman Blues was a bit heavy, but that is mild criticism.

Mostly this album is about Dan Treanor’s love for blues harmonica. His licks are actually infrequent, but always beautifully soulful. I’ve already heard phrases I plan to steal.

I give this album a IV+ on the I-IV-V scale of blues harp excellence. Highly recommended. Contact Dan Treanor to find out how to get the CD: daniel2102@comcast.net

Wednesday, December 8, 2010

The Mission Chicago 32-20 Harp Amp

Bruce Collins at Mission Amps tells me the Chicago 32-20 amp is selling extremely well. Players are buying it for the warm crunchy tone and great features you can’t find on any other amp. You can switch the amp from fixed bias to cathode bias which changes the texture of the tone. You can use the DEEP switch to fatten your sound, like the loudness switch on old Hi-Fi gear. Another switch disables the cathode bypass capacitor. All these adjustments allow you to tailor the basic circuit design of your amp to your tonal tastes.

Players are also choosing the Chicago 32-20 amp because of its tremendous value. At only $999 it is hundreds less than other amps in its class. Every Chicago 32-20 amp is hand-built by a master amp maker who is known worldwide for tone. Bruce uses only New Old Stock (NOS) military-grade paper in oil tone capacitors and solders every part himself.

When the amp was being designed, special attention was paid to the rectifier. The copper solid state rectifiers were tried but discarded in favor of real tube rectifiers. The copper solid state rectos deliver slightly more B+ voltage with less sag, which is why they give the impression of “tightening up” the sound, or making an amp sound more “crisp.” But that is at the expense of real tube sag and the warmth it provides. It would have compromised the true vintage tone of the amp. The rectifier tube is one of the tone generating components in a vintage tube harp amp, and solid state just doesn’t cut it.

Comparison: Kalamazoo amp vs. VHT Special 6

Once again, here is the video of Nic Clark playing the modified VHT Special 6 amp:

Here are three links to Youtube videos of the Kalamazoo amp:

Kalamazoo model 1 blues harp amp

custom kalamazoo harp amp model 1

Kalamazoo amp and BluexLab harp mic

The Kalamazoo amp suffers from a design that gives it that raspy harsh tone: It uses a single EL84 power tube, while the VHT Special 6 amp uses the warmer sounding 6V6 power tube. The 6V6 was the tube used in many classic harp amps from the glory days of tone… Amps such as the Fender Champ and Princeton, vintage Gibson amps, the National/Supro amps, the classic Premier amps like the Twin 8, and cool old PA amps like the Newcomb E-10B.

I cannot think of any classic harp amps that used a single EL84 tube. The EL84 has a characteristic tone that I call a “crackly mush.” The tube has a very low negative bias voltage, so the tube is driven to square wave distortion very easily. I wrote about the details of this problem here: EL84 Harp Amps.

The 6V6 tube has a much warmer tone and smoother distortion, which is why it was the choice of so many of the great blues harp players of the 50s.

The Kalamazoo amp has been popular as a low cost practice amp for harp players. One particular vendor rehabs these old amps and sells them for $269 for a “beat up Model 1,” and up to $379 for a “really clean Model 2.” No matter which one you buy, you still get and old amp made of particle board that often disintegrates when exposed to moisture.

For less than $200 you can buy a brand new VHT Special 6 whose cabinet is made entirely of finger jointed plywood. Its circuit is soldered point-to-point on an eyelet board, and it is guaranteed for 5 years (90 days on speaker and tubes). The amp circuit is essentially a vintage Fender Blackface Champ, with a 10-inch speaker in a larger cabinet.

When bench tested the VHT amp produces an honest 6 watts of power right at the point it begins to clip. It is very loud for a small amp. The Kalamazoo amps produce about 3 watts at the point they begin to clip. Some vendors claim the amps put out 8 or 10 watts, but that is an exaggeration and does not comport with the generally accepted methods of measuring amp power for the purpose of comparison.

Right out of the box the VHT is a much better harp amp than the more expensive Kalamazoo. Its tone is warmer and more dynamic, and much bigger and less boxy. For about the cost of the “beat up” Kalamazoo amp you could purchase a brand new upgraded VHT amp that is among the sweetest I have ever heard.

UPDATE: From Wikipedia - "When overdriven, the EL84 power tubes in these amplifiers produce a distinctive chiming, articulate, treble-heavy sound..." Yep, that's what I hear when harp is played through the Kalamazoo and other EL84 amps.

Sunday, December 5, 2010

Nic Clark playing the Modified VHT Special 6 amp

Great tone, eh? And it sounds huge. The amp was on 3 (9 o'clock on the volume control) and everybody was like, "Holy crap, that thing is loud." This was during a break at Ronnie Shellist's blues harp workshop last Sunday.

Tuesday, November 30, 2010

VHT Special 6 Amp - Modified for Blues Harp

This is an amazing little amp to start with, and these mods make it even better.

Bruce Collins at Mission Amps modified the voicing and tone stack as described in the previous blog post. The changes were actually very small: a few components on the eyelet circuit board. Anybody who can solder could do it.

I installed an Eminence Lil' Buddy speaker, mostly because it has a hemp cone similar to the Cannabis Rex speaker I use in my Mission Chicago 32-20 amp.

The amp has a JJ Tesla 6V6 S power tube in it in this video, but the stock power tube sounds the same.

The delay pedal -- with a small amount of delay -- is ON when the video starts. The delay is OFF after you see me hit the button.

Here are the differences I hear in the modified amp:

-It is louder than the stock amp. The Eminence speaker is more efficient.

-It is warmer/darker than the stock amp. Bruce voiced it lower, and the Eminence speaker is less bright. IMPORTANT NOTE: The amp is sitting on a pedestal in this video, up off the floor and away from the walls and corners. That gives it a truer sound, with less exaggeration of the bass tones. If you put the amp on the floor or against the wall the bass with be more apparent.

-The sound is bigger and less boxy.

-The break-up is more organic. The stock amp had a slight crackly, reedy quality to the tone.

-The amp tips over into nice distortion when you push it a little bit. You can hear that in the second part of this video when I play the blues riff a second time a little harder. This is because of the circuit mods.

-The amps seems more dynamic and musical. I gotta tell ya... it is a blast to play!

I played this amp at a loud blues jam at Ziggies Saloon in Denver on Sunday and it did well. I got lots of nice comments on my tone. It is not as robust and powerful as my normal gig rig, so I had trouble hearing myself in the loudest moments. The next mod will be a line out, so I can put a bit of the amp through the monitors. That will be perfect. In all but the loudest situations I think the amp will do just fine by itself.

So, I paid $200 to Amazon.com for the amp. It arrived in five days, no shipping charge. The speaker sells for $75. There is no real need to change the stock tubes unless you are an inveterate tinkerer (like me). The tubes sound fine. For $275 you can own a killer little harp amp that beats the pants off the EL84 amps like Kalamazoo, Epiphone, and Fender Pro Jr.

With the circuit mods the amp steps up to a whole new level and becomes a true harp amp. It has the tone and feel you crave... It's a boutique harp amp for a fraction of the cost.

I am thinking of offering a kit for the circuit mods. If there is interest in this, let me know. I will produce detailed instructions including a video, and include all parts and wires. I may also offer complete conversions. If I get some demand for this I'll come up with some prices and publish them here. The price of the mod kit would be quite modest, for sure.

Wednesday, November 24, 2010

VHT Special 6 Harp Amp Project – Step One

Today the Special 6 project amp spent some time at Mission Amps in Denver for testing and first-step harp mods. Here is what I can tell you:

-The amp produces its rated power of 6 watts with about 5 percent distortion at two o'clock on the volume control (it is not numbered). Feedback is well controlled. The amp is very well made, with a hand-crafted circuit similar in design to a blackface Fender Champ from the mid-60’s era.

-Changing to a 6L6 power tube in the amp does nothing to increase the power or improve the tone. It sounds and performs better with a 6V6. Also, the magnet on the stock ceramic speaker makes many 6L6 tubes a very tight fit.

Right out of the box this is a very good harp amp. It is among the most harp-friendly guitar amps I’ve seen. A harp player could buy this amp and do nothing to it, and get great tone from it.

But the amp does have a few compromises that can be improved upon to make it more suitable for outstanding blues harp tone:

-The slope of the tone stack is too trebly. It needs to be shifted downward.

-There is a slight reedy quality to the tone that detracts from its warmth.

So, we decided to make a few simple modifications to the tone stack, making it more like the circuit in a tweed Bassman amp. Each of these mods was tested by playing the amp to ensure the tone was improved in the way we expected. We sometimes had to try several different component values to get the tone just right.

We changed the tone stack slope resistor, the bright cap, and the cathode bypass cap, and changed the plate voltage on the preamp tube.

The result is a smoother, warmer tone without the reedy quality. The voice of the amp has been shifted downward, and its tonal girth has been enhanced. It retains the nice crunch and grit. It is a very fine sounding blues harp amp.

Remember, at this point the amp still has its original tubes and speaker, and I am in no hurry to change them. I suspect the speaker will break in well, and the stock tubes sound great. I’ll try other tubes later, after I’ve played it more and made certain the circuit mods are as they should be.

UPDATE 11/26/11: The amp is substantially louder now. Same room, amp settings, mic, and harp. I suspect the speaker got broken in during all the hard playing at Mission Amps while we were proto-typing the mods. The tweaks to the tone stack also focus more of the amps energy on the harp spectrum.

Jump to review of this amp with mods

Tuesday, November 23, 2010

VHT Special 6 Amp - First Impressions

My new VHT Special 6 amp arrived a couple of hours ago and I've already given it a hard workout. My first impressions? I'm impressed! Very impressed. This little amp sounds great right out of the box.

The VHT Special 6 is a point-to-point wired tube amp that sells for $200.00. The power tube is a 6V6, the same tube that powered vintage Fender and Gibson amps and has such wonderful natural harp tone.

Here are a couple of videos I made within minutes of the UPS guy dropping it off. In the first vid I am playing a bullet mic with a Shure CM element, very similar to a vintage Green Bullet mic. In the second video I'm playing a Front & Center mic with a crystal element.

The Shure mic is plugged into the "Lo" input and the F&C mic is plugged into the "Hi" input. Otherwise, the controls were the same for both.

This little 6-watt (nominal) amp has caused me to rethink my favorite starter amps. Already, this VHT seems to have more volume and much better tone than the low-priced EL84 amps such as the Epiphone Valve Junior. It's 10-inch speaker blows away the Fender Champion 600, and it just runs rings around the old Kalamazoo amps. The amp has a natural warmth and crunchiness and it responds well to the pressure you put on the microphone. It is essentially a blackface Fender Champ with 10-inch speaker for $200. Amazing.

The VHT Special 6 amp begs for mods with its intelligent open design, eyelet board, and point-to-point wiring. The next step will be to take this little gem to Mission Amps in Denver for bench testing and upgrades. As I said, stay tuned...

Jump to Step One Mods

Thursday, November 18, 2010

VHT Special 6 Amp

Yesterday I ordered the VHT Special 6 amp from Amazon.com. This will be a new harp project amp, with great potential. Stay tuned on this one....

Monday, November 15, 2010

Update: Mission Chicago Amp

Bruce Collins has posted a few interesting details to his Mission Harp Amps website. He has changed the name slightly to the Mission Chicago 32-20 amp. As far as I know there are no changes in the design or features or sound.

One detail he added concerned the output transformers used in the amp: "Custom made, oversized windings and vintage style open frame, paper bobbin." These are the same killer OTs he's used since the amp was first offered for sale.

Bruce recently shipped a Chicago amp with 5881 power tubes that produced 41 watts in fixed bias mode. Crikey! It retained all the warm tonal qualities of the 6L6 amps, but with more bark and punch. What a beast...

Update: My bad... The tubes Bruce used in the 32-20 amp to get 41 watts were 6L6WXT+ tubes. You can order the Chicago 32-20 amp with these tubes, no extra cost.

Smackdown! – Harpgear HG35 vs. Mission Chicago 32-20

Let me say right up front that I think Brian Purdy at Harpgear makes excellent harp amps. For years I have recommended to my students and others that they buy the Harpgear HG2, a 5-watt tweed Champ clone with outstanding tone and build quality.

I’d heard and played the HG35 amp on several occasions, and at a blues jam last night I had the opportunity to play both it and my Mission Chicago amp and do a close comparison.

The two amps are similar: The HG35 claims 35 watts of power, while the Mission amp claims 32. They are both built in tweed cabinets of roughly the same size, with the Harpgear amp using two 10-inch speakers and the Mission amp using a single 12-inch speaker.

The basic circuits are similar, with twin 6L6 tubes providing the power in each amp. These tubes are cathode biased in the Harpgear amp, and that presents one of the biggest contrasts between the two: The Mission amp is switchable from cathode bias to fixed bias, and I prefer to play it in the fixed bias mode.

I have been curious about the Harpgear HG35 for this reason: Claiming 35 watts from a cathode biased 2x6L6 amp is unusual. Using the standard method of measuring output wattage, it is tough to get more than about 25 watts from this configuration in a harp amp.

This difference was evident last night when I played the two amps on stage at a blues jam. The 32-watt Mission amp is substantially louder than the 35-watt Harpgear HG35. In fact, the Mission amp has a remarkably fuller tone at half volume than the Harpgear has at three quarters volume.

Both amps produce good tone, but the Mission amp produces a bigger tone with noticeably more crunch and bottom end. I switched back to the Mission amp because I was concerned I would not be heard in the loud jam setting.

The Harpgear amp has a cleaner sound, and I am sure that is a feature that Brian designed into the amp. His amps are known for this. The amp sounded brighter and more directional. It was a bit more prone to feedback.

When I switched the Mission amp to cathode biased mode its volume dropped to a level similar to the Harpgear amp, but the tone retained more of a vintage-style warmth. Overall, the Mission amp breaks up more readily than the Harpgear amp.

For those who prefer a cleaner tone and always play in situations with low-to-moderate stage volume, the Harpgear HG35 could be a good choice. For players looking for a bigger crunchier tone, the Mission Chicago 32-20 amp might be a better choice.

Tuesday, November 9, 2010

Interview at Ziggies

We were interviewed during the Sunday Blues Jam that we host at Ziggies in Denver. Charles Billiris (guitar player/singer) and I are standing out on the sidewalk in front of the club while the jam goes on.

Sunday, November 7, 2010

The Truth About Gear

It is an arcane debate that rages forever on music forums and elsewhere: How important is gear to your tone?

The Curmudgeons in this argument insist tone comes only from the player, and too much attention is paid to gear. The Gear Heads lust after one piece of gear after another, dreaming that some combination of hardware will give them that perfect blues harp tone.

I’ve been in both camps at various times. Here is the truth about gear:

-No matter what gear you use, you will still sound like you. People who are familiar with your playing will still immediately recognize it and most of those people won’t notice much difference no matter what gear you are playing.

-Players spend an enormous amount of time and money on custom gadgets that do not improve their tone, and in fact may make it worse. This includes vintage or custom mics, pedals, amps, harps, etc.

For good blues harp tone you need an amp and a mic, period. Let’s start there. After you are satisfied with your tone it is fair to experiment. But when I read (rather frequently) about new players spending big bucks on a custom harp amp and then throwing a bunch of pedals in front of it I cringe.

A custom harp amp will not improve your tone, technique, or playing, except to the extent it inspires you to practice more. And a good-sounding amp will certainly raise your level of excitement and commitment to the craft. The value of a custom harp amp is this: It allows you to focus on your tone. It will be less likely to have screaming feedback, and it will have the potential to reward good playing. It can make you a better player if you work at it.

You don’t need an exotic vintage or custom microphone. You most certainly don’t need a “HOT HOT HOT!” element, as advertised on eBay and elsewhere. That high output will kill your tone, and the flame paintjob will be indifferent to your tooting and honking. Much money is wasted on expensive mics that do nothing to improve your tone.
If you have a good harp amp (see above) you don’t need any pedals except for perhaps a simple delay pedal. A complex pedal chain is a waste of your money and an impediment in your quest for good tone. And, the arguments over which delay pedal is best are often absurd. There is nothing about blues harmonica that demands a certain circuit in a delay pedal. As long as the pedal sounds good to you it is perfect. The pedal I use costs $60 and sounds great.

If you aspire toward good blues harp tone you don’t need $200 custom harps or demon tweaks from high-priced amp Gurus. You need a good basic rig: a harp amp and mic, and maybe a delay pedal. You need these working tools, and that’s it. Other players don’t sound better than you because they have exotic or expensive gear. They sound better because they practice more or are simply more gifted.

Friday, November 5, 2010

Bugera V5 Amp

Yesterday I was over at Gary Yates' house to practice harp and go over some points from Ronnie Shellist's harp workshop last week. Gary had a little Bugera V5 amp set up and I played it for a few minutes. It was fun!

The tones from the amp are good, and feedback was not a problem. Gary had a small tube preamp hooked up but I preferred the sound when I plugged straight into the amp.

It's a little 5-watt bugger with a 12AX7 preamp, an EL84 power tube, and a solid state rectifier. Controls are gain, tone, volume, and reverb. Fiddling with the gain and volume I was able to get some pleasing harp tone. The digital reverb is usable but a bit too watery.

It also has a power attenuator on the back panel, but this will be a lot more useful for guitar heroes than for harp players. It has settings for full power, 1 watt, or a tenth of a watt.

Interesting feature: It has a headphone out connection; a 1/4 inch jack that would work fine for a line out into a PA system.

The Bugera V5 sells for about $150. It is certainly worthy of consideration if you're looking for a small harp amp and your budget is modest.

Thursday, October 28, 2010

Fender Champion 600 Mods

The Sunday blues jam my band hosts at Ziggies in Denver was a madhouse last week. There was a full house of jammers and fans, and it cranked up to a really gonzo level. It was loud, rockin’, and fun.

AC Blue came in late with a cool little Fender Champion 600 amp he wanted to try in a live setting. This is a little 5-watt amp with one 6V6 power tube, way too wimpy for blues jams. It sells new for about $150.

Earlier in the week AC had taken the amp to Bruce Collins at Mission Amps to make it more harp-friendly and add a line out. Bruce changed out some of the tone capacitors to reduce the highs and boost the low mids. He lowered the preamp tube plate voltages and dropped some of the first preamp stage gain.

AC is also a wicked keys player, so his idea was to use the new line-out jack to route the little amp’s signal through his big solid state keyboard amp when he is playing harp. That’s what he did at the jam.

It sounded great. The tone was warm, with plenty of rip and grunt. It cut through the loud blues jam like a hacksaw.

He was using the little amp like a pedal; you sure couldn’t hear it by itself. But, after the jam was over he still had a cool little practice amp with nice tone.

The jam was so busy and rowdy I neglected to get photos or video of AC’s amp. Bummer, maybe next time. I’ll update this post then.

Sunday, October 17, 2010

Review of the Mission Chicago amp from Mojo Red

[NOTE: Mojo Red -- AKA Ken Mergentime -- is a very fine harp player well known to the blues harp commmunity. He sent this review unsolicited to the Harp-L list.]

I own the first production version of the Chicago amp by Mission (built by Bruce Collins). I've been playing through it for several months now and I LOVE it. It's got some great features for harp players and looks just beautiful with its tweed 1950s Fender style cabinet.

Anyway, here are my impressions:

Things I love:
- The lacquered tweed cabinet (Fender 1955 Wide Panel Deluxe) is beautiful!

- The single 12" speaker (Eminence Patriot "Cannabis Rex") is VERY efficient and can handle a whole lot of output without breaking a sweat.

- Plenty of power (@ 35 watts) so I'm never buried in the mix unless I want to be.

- GREAT set of natural overtones. This thing is rich with overtones, and just sings! The more I play through it the more I love it as I discover -- through varying my attack, vibrato, cupping techniques, tongue slaps etc. -- that this amp really responds spectacularly well, and offers a very nice pallet of tones.

For example, by using a delayed attack on a low harp, I can get a wonderful trombone-like sound (a-la-Dennis Gruenling). This I never expected, and really kicks butt on those slow blues numbers, especially 3rd position minors.

- I love the "Deep" switch which boosts the bottom end response. I just leave that sucker on all the time. Playing a low harp, like your G or Low-D can be a powerful experience -- it's all out front, despite the band's volume. This is a GREAT feature!

- I love the line-out on this amp as it has it's own volume control on the amp! I've had several occasions to use it now, and it's MUCH better than micing the amp. Once set up, if I need more through the mains, I can tweak it myself (drives the sound guys crazy).

- The tone (bass/treble) controls really REALLY effect the tone (what a concept). Other amps I've used, the tone controls seem wimpy for harp.

- The amp has two inputs (Hi and Lo) for using different types of mics. I'm using the Lo input for really hot mics, like my 1950s Green Bullet and my super-hot wood-bodied crystal, and use the Hi input for lower-output mics, like my JT-30, or my RE-10.

- It comes with a switch that allows you to change from cathode bias to fixed bias on the fly. The difference is subtle to my ears, but one provides a little more vintage sound to my ears, so I leave it there (not sure which bias that is, however, as they are not marked).

- It has a gigantic 50-watt power transformer which I'm told is the secret for the HUGE bottom end you can project.

- The feedback resistance on this amp is phenomenal, even at hi volumes. Not completely immune, but easily managed.

- I haven't added any pedals to the amp yet, but Bruce tells me it's very "pedal friendly" whatever that means. I'll take his word on that as he's come through with everything else he's promised.

- Bruce, incidentally, is GREAT to work with. Since mine was the first production model, he would often come to my band's weekly blues jam to hear for himself how the amp was breaking in. He actively solicited my thoughts/impressions as a player. Bruce, BTW, is an engineer who really knows his stuff. He's been building custom tube amps for guitar players since the 1980s. The Chicagoamp is his first go at a purpose-built harp amp and he's hit a home-run in my opinion.

- The pricing on this amp is fantastic. Much less than comparable harp amps from other custom builders, yet the quality is still amazingly high.

Things I don't love:
- Initially, I found my amp to be a little edgy/harsh with high-key harps (at higher volumes). I went back to Bruce for a little tweak. Bruce then installed an additional toggle switch inside the cabinet that he calls the "crowd-friendly" mod. It cut the harshness right out of that puppy without sacrificing power or projection. However, if I find myself on stage with some guitar shredders, I can still flip that toggle and it will have more cut, but I don't need that for what I generally play.

- In addition, the speaker itself, being brand new, needed a few hours of stage time to mellow out. It did mellow out a LOTafter about 20 hours of play. Now it's smooth and creamy.

- At 35 Watts this thing needs a bit of push to get it to break up like smaller amps, but I can still get around that by pushing the volume on the amp and holding back the overall volume using the VC on my mic. I'd like a little more break-up sometimes, so I'm thinking about picking up one of those "Harp Break" pedals from Lone Wolf for when I want a more over-driven sound. Might add a delay pedal as well for a little slap-back when I want it.

- As a player, I wish I had a better vibrato... Other players with great vibrato pull more out of this amp than I can... but that's not the amp's fault. :-)

Wednesday, October 13, 2010

The Nighthawks - Mark Wenner harp solo

Mark plays a Shure Green Bullet mic into a stock '59 Fender Bassman re-issue amp (1991).

This was at the Toad Taven in Denver last night. Great show!

Tuesday, October 12, 2010

Steve Marriner

Steve is playing through his Astatic T-3 crystal mic and an original blackface Fender Super Reverb amp.

Tuesday, August 24, 2010

“The 5f2h amp is ridiculously awesome”

A note from Bill L. in NY, the lucky harp player who bought my 5F2H harp amp:
“The 5f2h amp is ridiculously awesome. It screams, growls, honks, kicks ass and is pretty thunderous for a ten-watt amp. I played it on every volume setting from 4 to 12, and I found a tone control setting that works for each volume. The amp simply shines. It made me want to play less notes and be more toneful with each note... I am thrilled with it to say the least. Your recent blog post about the basic elements of quality harp tone comes to mind -- the 5f2h exemplifies all those qualities. I couldn't imagine ever needing anything else.

The new Mission amp must be truly a thing of wonder for you to be able to part with the 5f2h.”

Wow! Thanks, Bill!

Bill brings up some interesting points about the 5F2H harp amp that I thought I’d expand upon a bit here.

It was originally designed by Bruce Collins of Mission amps as a pure harp amp, inspired by the tone circuitry of the classic 1960 Premier Twin 8 amplifier. Weber sold it as a kit in a smaller cabinet with a 10-inch speaker. The one I sold to Bill is in a larger tweed Deluxe cab with a 12-inch speaker.

During the two years I owned and played the amp I learned much of what I know about good harp amp tone and how to wring it out of an amp. I spent many hours testing and listening to different components and circuits in the amp to get that fat chunky harp tone we all crave.

Indeed, much of the philosophy behind the amazing Mission Chicago amp came from my experience with the 5F2H. The Chicago amp has much different circuitry, but shares some of the same demon tweaks. They have the same sonic DNA.

Bill’s 5F2H amps was my gigging amp for a year, and was the prototype for a new small harp amp from Mission, named “The Memphis.” Contact Bruce Collins at Mission Amps for details.

Monday, August 23, 2010

IBC Update

There are four preliminary rounds in Denver’s International Blues Challenge competition this year, and three of them are finished. My band Roadhouse Joe won the first prelim, beating some solid local blues acts with good credentials: Catfish Cray, Teresa Lynn, Eef and the Groovy Blues Express, Another Kind of Magick (an amazing group of young teens from Cheyenne WY) and a couple other bands.

The second prelim was won by Papa Juke, with harp player/band leader Mad Dog Friedman. Lionel Young won the 3rd prelim round. I was there at the Outlook in Boulder to watch and it was one helluva show.

Lionel Young won it all in 2008. He entered as a solo/duo act and took top honors in Memphis. The band he put together for this year is tight and talented, with a polished stage presence. He beat some great bands yesterday in Boulder, including Taylor Marvin, The Mighty Jivesters, and Eric Boa and the Constrictors.

Now, my band has to face Lionel in the regional finals on Sept 12, and we’ll need our A game (and then some) to advance to Memphis.

Interesting note: All of the winning bands so far in the prelim rounds have harp players, and harp players have been rather scarce among the competitors.

The last of the prelim rounds is next Sunday at the Toad Tavern in Littleton. There are some really strong bands in this round, including The Informants, Doc Brown, and Rachel Jane & The Hurricane.

I’m excited about the finals. It’s fun to play and compete against such talented bands. The Denver metro area has about 3 million people and a surprisingly robust blues scene. The quality of players at my blues jam is impressive, and the number of good blues bands is remarkable when you get them together to compete.

UPDATE: Here is the band that won the last prelim round of the local IBC, The Informants.

UPDATE II: The Lional Young Band won the finals. We kicked ass, took names, had a blast, and settled for second best.

Thursday, August 19, 2010

Good Harp Amp Tone: What to Listen For

This is one of the most frequent questions I get: “What amp should I buy to get that old-school Chicago tone?” Here is my advice:

First, throw out any preconceived notions you may have picked up about harp amps. Forget about the name on the amp, the speaker configuration, and any hype. Just listen.

Since you’re listening for Chicago blues tone, you should start with a basic tube amp. Forget solid state amps and fancy amp modelers. They won’t get you THAT tone. They certainly have virtues, but if you want the full, warm, growly tone of 50’s Chicago you need to play what they played: basic tube amps.

Listen to sound clips/videos from the amp maker or owners of the amp. Look for clips that aren’t larded up with reverb or delay. Try to find examples of solo playing as well as band situations.

Rule # 1: A good harp amp should mimic the tonal qualities of a good male blues singing voice.

Listen to the highs. Are the highs sharp or piercing? Shrill tone gets old very fast, causing listener fatigue among your audience. (It also can exacerbate feedback problems.) You can try adjusting the tone controls, but that may cause the amp to sound muffled. You want the highs to sound warm, with the sharp edges rounded off.

Does the amp sound nasal? This is caused by too much emphasis on the high mids. It’s usually a feature of the speakers or tone stack. You want the tone to be open and full, with an easy evenness to the tone from low to high.

Does the amp sound boxy? You’ll know this when you hear it. It is caused by too much midrange. Imagine a small radio squawking away loudly on a table. The combination of speaker and cab size contributes to this.

Listen to the lows. This is the heart of good harp amp tone. The lows must be very “present” in the amp mix. Blues harp playing puts tremendous pressure on the low register of your amp, so it’s gotta have some punch. Not boomy or “farty.”

In other words, a good harp amp needs to have an even character for all tones from low to high. That character should have a little hair on it… a very slight touch of mild distortion on the leading edge of notes. An amp that is too clean will not get you to that Chicago-style place you want to be.

Keep listening:

Listen to single notes. Should be warm and full, never thin or shrill.

Listen to chords. The big fat low chords should jump out of the amp. It takes power to give these chords the dynamics they need. The chords should sing, never sounding mushy.

Listen for when the player bears down on the mic, using a tight cup for a big sound. The tone should widen, picking up some harmonic distortion.

And MOST IMPORTANT, listen to the little transitions harp players make: Moving from a single hole to a double stop or a split, or a tongue slap, a trill that is slightly bent… all the tones that make blues harp so distinctive. These techniques cause the reeds to pop and rattle a bit, and your amp needs to reproduce that very well.

Ignore the hype and trust your ears. Weed out the amps with weaknesses that get more annoying over time. A good harp amp is a thing of beauty that becomes as much a part of your sound as your harmonica. This outline should get you pointed in the right direction.

Tuesday, August 17, 2010

Roland Cube Street

I like this video, and I've always liked Roland Cube amps for harp.

Nic Clark website is up

Blues Harp prodigy Nic "Cottonseed" Clark has put up a website: www.nicclarkblues.com

Monday, August 2, 2010

We Won!

Well... it was only the first round of the International Blues Challenge, but The Roadhouse Joe Blues Band took first place! Now it's on to the regional (Denver area) IBC finals on Sept 12. Then... Memphis, baby!

The Mission Chicago amp killed, with huge fat tone. I added a little delay, set it on Fixed Bias, volume on 5. Sounded great. You can see the amp behind me in this photo.

And.... yes, I am that tall.

Thursday, July 29, 2010

The Snakeskin 5F2H Harp Amp is for Sale

UPDATE: This amp has been sold.

This is a one-of-a-kind amp designed and built specifically for excellent blues harp tone. It is 10 watts of vintage 6L6 attitude. I offer it for sale for $500.

It began its life as 5F2H kit from Weber, assembled by Adam at Tungsten Amps. The 5F2H harp amp circuit was developed by Bruce Collins of Mission Amps, inspired by the Premier Twin 8 amp of the early 60s. When I acquired the amp I took it to him for tweaks. It has a wonderful unique tone.

It was originally ordered from Weber with 12-inch speaker in a Deluxe-sized cabinet, while normal 5F2H amps have a 10-inch speaker in a smaller cab. It is a vintage Mojo Tone MP12R alnico speaker, their version of the classic Jensen speaker with the seamed, ribbed cone. It has the warmth and snarl of the old Jensens.

The amp is pure Class A, with one 6L6 power tube, a 5U4 rectifier tube, and a 5751 preamp tube. New spare power and preamp tubes (and fuses) are included, packed in bubble wrap and tacked to the inside of the cab, right where you need them if a tube pops during a gig.

Bruce Collins upgraded the tone stack with excellent K40Y paper-in-oil caps. He optimized the biases and voltages of the tubes for killer blues harp tone and installed a beefier output transformer. And he voiced the line out so that it is the best sounding I’ve ever heard.

You can hear this amp at my band website. Click the music player at the bottom of the web page to hear three songs featuring the 5F2H amp. I gigged this amp many times over the last year, and kept it in perfect condition. It was always covered and gently handled. There are no marks or scuffs on the amp.

It is loud enough for most gigs in small to medium rooms. I used the line out at bigger gigs, using the amp as an on-stage monitor. The amp weighs only 29 pounds.

Wednesday, July 28, 2010

COMPARISON: Mission Chicago Amp vs. Sonny Jr. Cruncher

I was listening to samples of the Sonny Jr. Cruncher amp at his website, and I was struck by how different it sounds than the Mission Chicago amp. Check it out:

Here is an audio link to “Sonny Jr. Presents the Cruncher”

Now listen to the Mission Chicago Amp

The difference is startling, eh? I applied NO effects or EQ to either recording, just edited for brevity and normalized the levels.

-The SJ Cruncher is rather bright while the Chicago is deep.
-The SJ Cruncher sounds horn-like.
-Those thunderous fat chords on the Chicago amp will jiggle your liver.
-The Chicago amp seems louder, with bigger tone and more flexibility.

And… the Chicago amp costs about $500 less than the SJ Cruncher.

You can set the Chicago amp up to sound bright like the SJ Cruncher if you want to. There are a lots of audio and video samples at the Mission Harp Amps website.

Tuesday, July 20, 2010

Sunday, July 11, 2010

Dan Treanor's Blues Harp Blowout with RJ Mischo

The Old South Pearl Street Blues Festival in Denver, July 10 2010 - Dan Treanor's Blues Harp Blowout. This is the finale, with RJ Mischo, Ronnie Shellist, Clay Kirkland, Teresa Lynne, Al Chesis, Nic Clark, and Dan Treanor. They are all playing through RJ's chrome JT-30 microphone and a Fender blackface Super Reverb amp.

It was a great summer show. There are lots more videos from this festival at my YouTube channel.

I'll be playing at Dan Treanor's 4th Annual Rocky Mountain Blues Harp Blowout in October. Can't Wait!

Thursday, July 1, 2010

Line 6 Relay G30 Digital Wireless System

Several readers have written to ask about the Line 6 X2 XDS95 Digital Wireless System I bought last year. Yes, I still use it and like it a lot. It has never given me any problems, and it is perfectly quiet and solid. The problem is, it has been discontinued by Line 6 and is no longer available.

This looks like its replacement: The Line 6 Relay G30 Digital Wireless System. The specs look very similar: a compact digital wireless with 100-foot range. A few changes are apparent: It uses the 2.4 Ghz frequency range, while the X2 broadcast on 900 Mhz. Another change is the price, with the newer model costing 100 bucks more. Still, for a sales price of $299 it looks like a good buy, and Guitar Center (where I bought my X2) was willing to deal. It includes a power supply, which the the X2 did not, and it has six channels, one more than the X2.

I haven't tried this unit yet, but if it takes up where the X2 wireless left off it is a great tool for harp players. If any of you get the opportunity to try this unit I'd like to hear your impressions.

Wednesday, June 30, 2010

True Bluesman

Dan Treanor at a blues jam at Ziggies in Denver on Tuesday night. His harp was singin'. Dan is a great blues entertainer, a true bluesman.

Tuesday, June 29, 2010

Bends Harmonicas

I've added a new link in the list to the right: Bends Harmonicas in Brazil. I've heard good things, would love to try them.

Thursday, June 24, 2010

Al Chesis

Here's a short clip of Al Chesis on harp, Jeremy Vasquez on guitar, Kyle Borthwick on drums, John Blake on bass. Al is using his vintage Astatic JT-30 microphone w/ceramic element plugged straight into the amp; no delay or other pedals. Nice tone!

Wednesday, June 23, 2010

New Feature on the Mission Chicago Amp

Bruce Collins has added an interesting new feature to the Mission Chicago Harp Amp – but it bears a little explanation:

It is a Cathode Bias Bypass switch, but you can think of it as a FAT or BOOST switch. It switches on or off a circuit that regulates the power to the preamp tube, a 12AX7.

In the ON position the amp has the same circuit as in my prototype version of this amp: The tone is tweaked for what Bruce calls a ‘chunky-modern” tone. In the OFF position the bypass is disabled, giving what Bruce calls a “politely vintage” tone.

When the switch is ON the amp cranks out more gain; say 6db more. I played an amp with this new feature at our blues jam at Ziggies in Denver last Sunday, and the tone difference was distinct. With the switch OFF, the tone was warmer, fatter, um... wider. It lost a bit of volume but took on a sound that reminded me of my 1953 MASCO ME-18 amp.

The switch is a small toggle on the underside of the chassis next to the preamp tube socket. It is not hard to reach when you know where it is. You can reach behind your amp and flick it and hear the tonal change immediately.

The Mission Chicago Amp must be the most versatile harp amp on the planet. Look at the unique controls:

-Switchable from Fixed Bias to Cathode Bias (punchy to crunchy)
-DEEP switch (changes the tone stack curve for surprisingly low growl from a mid-sized 1x12 amp)
-and now, this new Cathode Bias Bypass switch (it needs a new name)

Along with the separate bass and treble controls, these switches make the amp infinitely adjustable to your taste. Nobody else is making harp amps like this.

NOTE: I played my Mission Chicago Amp at a private party in the huge backyard of a VERY swanky mansion last Saturday. We were on a deck facing the yard (more than an acre), pool, gardens, etc. I had the amp up to 7 (out of 12) and the volume was more than enough to keep up with two loud guitars and the rest of a rocking blues band. The host loved our sound and paid us twice the agreed upon fee.

Tuesday, June 22, 2010

More Kim Wilson

Oustanding perfomance at the Greeley Blues Jam 2010

Friday, June 18, 2010

Hohner's Newest Official Endorser - Nic Clark

Congratulations to Denver harp phenom Nic Clark for becoming an official Hohner USA endorser. Nic is among the youngest Hohner endorsers ever; Stevie Wonder may have been younger at the time he was signed.

Although Nic is only 14 years old, his talent and tone on blues harp are spectacular, and his fame is quickly spreading. He is friends with and has shared stages with some of the greats, such as Rick Estrin, Kim Wilson, Jason Ricci, and many others. Andy Garrigue, Harmonica Marketing Manager for Hohner USA, summed it up this way: "Nic is awesome." Andy will add Nic to Hohner's artist list soon, and issue a formal press release announcing the endorsement.

Good on ya, Nic! You're on your way.

In this last video Nic trades harp licks with Al Chesis, another blues harp master and official Hohner endorser.

Tuesday, June 15, 2010

Silver Champ Sighting

Tommy Knox of the Clam Daddys playing through a silverface Fender Champ, one of my favorite harp amps.

Sonny Landreth

No harp content, but GREAT swampy guitar. This is Sonny Landreth's encore solo at the Greeley Blues Jam on June 12, 2010.

Monday, June 14, 2010

It's Amazing....

...how many blues harp players spend a fortune on big boutique harp amps and sound like crap.

Then there is Kim Wilson who can use nearly any amp and sound good, even a guitar amp like the DeVille. That is inspiring.

Sunday, June 13, 2010

Two Fender DeVille amps for a Harp Rig?

Yep, that's what Kim Wilson was playing at the Greeley Blues Jam this year, June 12th. I've played harp through a DeVille and I thought it was one of the worst harp amps I'd heard: WAY too bright and spikey. But then, I'm not Kim Wilson.

There are two boxes on top of his amps: The one on the left is an ART Tube Preamp V3. What is that white one on the left? I looks like a pedal with no knobs. (click on the image to enlarge) I didn't get a chance to ask him about it.

Needless to say, Kim Wilson got good tone with these amps, and it was VERY loud. (watch the video) He was playing through his Astatic JT-30 microphone.


This photo was kindly sent by a reader, showing Kim Wilson's rig for a show in CT late last year. It looks like the Kinder Mid Bass Cut is in the middle, with a Kinder AFB+ on the right. The ART Tube Preamp is not evident here. (click on the image to enlarge)

Kim Wilson at the Greeley Blues Jam

Saturday, June 12, 2010


Gary Onofrio, the maker of Sonny Jr amps, contacted me yesterday and said he agreed with me about his advertising. Today he changed the claim on his website from this:

“Sonny Jr. Harp Amps are an investment that retain their value year after year”

to this:

"Sonny Jr. Harp Amps are an investment to last a lifetime"

Perfect. Gary deserves kudos for this.

Tuesday, June 8, 2010


My blog post about boutique harp amps as investments has created quite a firestorm out there in the online blues harp community. Gary Onofrio of Sonny Jr amps has this blurb on the front page of his website:

Sonny Jr. Harp Amps are an investment that retain their value year after year

As I pointed out in the previous blog post, Gary’s claim is not supported by any data I can find. In fact, it is clearly contradicted by a quick look at eBay transactions.

When I published this observation the reaction was funny. Owners of “Sonny Jr.” amps rose up with one voice and attacked me for having a bias or motive or agenda behind this. It was one of the clearest examples of the
ad hominem fallacy that I have seen.

“Arguments of this kind focus not on the evidence for a view but on the character of the person advancing it; they seek to discredit positions by discrediting those who hold them. It is always important to attack arguments, rather than arguers, and this is where arguments that commit the ad hominem fallacy fall down.”
It’s the kind of argument you get from 12-year olds or drunk sports fans. It is a dodge to avoid being forced to defend a clearly false statement, so they change the subject by attacking the messenger. It is weak.

I got a hilarious email from a guy who is very well known in the amped blues harp community whose argument was ENTIRELY based on my alleged bias or motive. Another person yawped that other boutique amps decrease in value, seemingly missing the main point that none of those other amp makers claim their products retain their value. Not a single person has tried to persuade me that Gary's claim is true, they just attack me for having questioned it.

I am not attacking Gary Onofrio’s amps (they are very good), nor am I attacking Gary. I am presenting an argument that his claim is false.
Here is an open letter to Gary Onofrio:


Several times you have contacted me and asked me to take down things on this blog which you thought were untrue or unfair, or which you simply disliked. I complied with your requests every time.

Now I am asking you to take down your claim that your amps are investments that retain their value year after year. It is demonstrably untrue and false. If you have any sense of duty to the truth, you will delete it. It reminds me of the worst kinds of phony ad hype, and it besmirches your fine amps with a cheap hucksterism not necessary to sell them.


-Rick Davis

Thursday, June 3, 2010

Are Boutique Amps an Investment?

Some boutique harp amp builders claim their amps are “investments” that hold their value over the years. I’ve heard owners of certain amps repeat the claim as if it were a fact.

Here’s the fact: It is a lot of hooey.

I’ve been tracking the selling prices of harp amps on eBay for a couple of years, and expensive new custom harp amps lose a significant amount of their value as soon as you take delivery and plug in your mic. That is the premium you pay for the name and the hype. Some are worse than others.

When you try to sell your amp (for whatever reason) you are going to be shocked about how you were misled, unless “retaining their value” means losing 40 to 50 percent when you sell. The priciest amps often take the biggest hits on resale value.

Sonny Jr 410 amps are often lucky to draw bids of $1100. SJ2 amps with the six 8-inch speakers go for around $800. Depending on the date, these amps sold new for nearly twice that. Is that what “retaining their value” means?

Scarcity and demand will keep the value of your amp higher. The big Harp King amp, for example, loses less over time.

Good lower-priced amps like the excellent Harpgear HG2 lose a smaller percent of their value when resold.

I’ve heard lots of unverifiable stories from enthusiasts for certain amps, claiming they resold at a profit. I doubt it. The open bidding system of eBay certainly doesn’t reflect that.

If you must have a harp amp that is truly an investment and will retain its value year to year, you’re pretty much stuck with vintage amps like the 50s Bassman or Pro, or the early 60s Concert. Problem is, these relics are too valuable to really gig. I can’t imagine dragging a ‘59 narrow panel Fender Pro in and out of the van for every gig. These amps appreciate in value when they are mint, not beat up.

Here’s the bottom line: If you like the way an amp sounds and it makes economic sense to you, buy it. Don’t be swayed by bogus claims that the amp is an “investment.”

Or... wait for some fool to pay the hype premium. When he puts it on eBay you can pick it up for a fraction of the inflated new price.

Friday, May 28, 2010

Nic Clark Channels Sonny Boy

This is at Erik Boa's blues jam at Q's BBQ in Denver on May 26. Nic Clark on harp. He's 14 years old!

Tuesday, May 11, 2010

How Loud is Your Amp?

You see it all the time when this topic comes up: The chart showing the ratios of speaker surface area. It shows that a 15-inch speaker is 1.5 times larger than a 12-inch speaker, which is 1.5 times larger than a 10-inch speaker, which is 1.5 times larger than an 8-inch speaker. So, will you get 1.5 times more loudness out of your amp with the bigger speaker? In a word, NO.

Total speaker surface area has almost nothing to do with perceived loudness. That chart is meaningless, but it certainly helps perpetuate a common amp myth.

Let’s take for example a typical 4x10 Bassman-style amp. It has 312 square inches of speaker real estate, compared to 113 inches for an amp with a single 12-inch speaker. So, is the 4x10 Bassman nearly 3 times louder than the 1x12? No, not even close.

Remember, it takes ten violins to sound twice as loud as one violin. That is an immutable law of psycho-acoustics and the nature of the human ear.

With the 4x10 Bassman you have 4 speakers sharing the output of a 45-watt amp. Each speaker is “seeing” 11.25 watts. Adding a second sound source (another 10-inch speaker) that carries the same signal does not double the perceived loudness, but makes the sound seem only slightly greater. The Bassman’s four 10-inch speakers each driven by 11.25 watts will have the same total perceived loudness of a single 10-inch speaker driven by the full 45 watts.

Now we will hear owners and makers of 4x10 amps cry, “But the four tens move more air!” Perhaps, but “moving more air” has the same effect on perceived loudness as speaker area. By itself, it has almost no effect.

The proponents of “bigger is always louder” are confusing sound intensity with sound loudness. Sound intensity can be measured by instruments as a linear curve, while sound loudness is perceived by the human ear as a logarithmic curve. (Keep in mind the ten violins.) When you stand in front of your big amp and feel all that air making your pants cuffs flutter, it might impress you but it has almost nothing to do with the audience’s perceived loudness of your amp.

If speaker surface area does not affect perceived loudness, what does? Simply put, the two most important factors are 1) the power you apply to the speaker and 2) the efficiency of the speaker. When the bigger-is-better crowd insists they need a big amp for bigger rooms, they are right only to the extent the bigger amp is more powerful. But a lesser-powered amp with a more efficient single 12-inch speaker can have the same perceived loudness as a typical Bassman-style amp. Better tone, too.

Additionally, the smaller amp is likely to weigh less and cost less. It is axiomatic with vintage-style tube amps that a small amp turned up sounds better than a big amp turned down. And since your amp can be mic’ed through the PA in nearly any gig, the reasons for using a big multi-speaker amp are pretty weak.

Saturday, May 8, 2010

In Defense of the 1x12 Harp Amp

I’ve seen a few remarks online by harp players maligning combo harp amplifiers that have a single 12-inch speaker. They take it as a given that the 1x12 configuration is known to be inferior for blues harp.

WTF are they talking about?

David Barrett has a Museum of Vintage Blues Harmonica Amplifiers at his Harmonica Masterclass website, and the most common configuration of all the amps listed is 1x12.

The list of legendary harp amps with a single 12-inch speaker includes (but is not limited to):

-Ampeg Reverbrocket
-Ampeg Jet
-Fender Tweed Deluxe
-Gibson GA20
-Gibson GA40
-Premier 120
-Silvertone 1432
-Silvertone 1482
-Kendrick Texas Crude

Indeed, the Masco PA amp that Little Walter was believed to have used had two 1x12 cabinets.

The Kendrick Texas Crude has been unfairly maligned by a certain competitor, which may have started this weird canard. I’ve played the Texas Crude and it is a beast: Loud, crunchy, and soulful, and remarkably feedback resistant.

Certain 12-inch speakers are well suited to harp tone. They have a great balance of fat lows and punchy mids, more so than other single speakers. Smaller speakers sound too pointy, and larger speakers sound too woofy. Amps with multiple speakers often cost much more then single-speaker combo amps, and they lose the cohesion of sound that emanates from a single driver. There is a very good reason so many classic harp amps are 1x12: They sing.

When I asked the question on Harp-L last year I got many different answers about the best speaker configuration for a gigging harp amp. Two very well known gigging pros replied with something like, “Just give me a good 1x12 amp.” I agree.

UPDATE: I thought of another great vintage 1x12 harp amp: The Flot-A-Tone amp my friend Al Chesis owns. Two 6L6 power tubes, great tone.

Tuesday, April 20, 2010

Just so you know….

I’ve spent a good deal of time and energy writing about the new Mission Chicago harp amp. Just so you know, I have no financial or business interest in the amp. If you buy one, I don’t make any money. If you don’t buy one, I don’t lose anything.

I did have a lot to do with the development of the amp. I spent many hours over several months researching and helping design the amp, and in particular testing the amp with different components and configurations to get that perfect natural harp tone. I am very excited about the way it sounds. The thing rips. It is EXACTLY the amplifier that I needed but could never find.

The builder of the amp – Bruce Collins, the owner of Mission Amps – is a good friend of mine. He is also the drummer in my band, Roadhouse Joe. And I own the prototype; I bought it, and it is now my regular gig rig.