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.

Saturday, April 17, 2010

Mission Harp Amps Website

A website for Bruce Collins' killer new harp amp -- The Mission Chicago Amp -- is now up: www.missionharpamps.com

Friday, April 16, 2010

Rick Estrin's Harp King Amp

Rick Estrin and the Nightcats were in town last Wednesday for a gig at the Toad Tavern. I arrived early to get a good seat. What a great show!

Rick had his trusty Kinder Harp King amp, similar to the one pictured above. It is a 6x10 monster with 100 (a hundred!) watts of power and Kinder's anti-feedback circuit. The amp sounded fantastic, with a huge, easy tone that seemed effortless.

Feedback was never an issue, but the band had such great stage volume discipline I was not surprised. Those guys played only at a moderate level and let the PA do all the work. I've played that stage several times; very good sound.

Estrin is a magnetic performer; one of the best harp guys out there. His guitar player -- Kid Andersen -- is a virtuoso and funny and engaging. His rhythm section is way in the pocket. As I was listening I realized the music was FUN. The whole thing made me smile.

Thursday, April 15, 2010

Nic Clark plays the Mission Chicago harp amp

Click on the Play button to start the video...




Tuesday, April 13, 2010

From Bruce Collins re: The Mission Chicago amp


The Mission Chicago 6L6 amp 32 watt, light weight, single 12" speaker combo.

I do have later plans to build the same type amp in the larger, tweed Super 5F4 2x10, tweed Bandmaster 5E3 3x10 and possibly the tweed Pro 1x15 cabinet layouts.

For a limited time, the introductory price of the first 15 Chicago 1x12 amps is only $999.99.

After the initial dozen amps are sold, the SRP (suggested retail price) will be around $1199-$1399, depending on the cabinet configuration and speakers.

The Chicago is not another Bassman or any other modified guitar amp. For this project, I used all my experience with vintage vacuum tube amplifiers, P.A.s, Premier amps, Masco amps, old Ampeg amps, tweed Bassman amps and other E series tweed amps. However, it is not a copy of any known amp... it is a true Harpsman's amp, dedicated to serious harp players. This is not a bedroom amp, it is a new harp amp circuit and totally rips.

It has a very broad, harp friendly bandwidth and gain structure that works well with a lot of different microphones. The amp is harp tuned and uses all standard vacuum tubes... there is no where to go but ^UP^ with NOS tubes if a player is so inclined. Any 12AX7, 12AY7, 12AT7, 5751, 5965, 12AV7, or 12AU7 can be used in this preamp stages for various tunings.

The standard design uses two matched SED Svetlana 6L6 power tubes and two JJ 12AX7/ECC83s preamp tubes with a Sovtek GZ34 rectifier. The chassis has a switch to run the power tubes in fixed bias or hot cathode biasing.

Cathode biasing reduces the absolute output power by about 25% but it has a softer fluffier vintage tone and over drive that is wonderful, while fixed bias makes the most amount of power, peak envelope power is about 45 watts

While operating the power tubes in the fixed bias mode, the amp is more feedback resistant and is a little snappier with more aggressive punch. The amp can be run with a 5Y3GT rectifier and two 6V6s for about 14-15 watts output or a GZ34 and two 6L6s/KT66 for anywhere from 24 watts to 32 watts clean depending on the combinations and fixed bias or cathode bias. When used with the 6L6s, you can use any normal octal socket rectifier such as: 5Y3G or GT, 5R4, 5U4G or B, 5V4G or GA, 5AR4, GZ30 or a GZ34. Tweak the amp's tone to your liking with any of these changes.

A very nice custom feature of the new Chicago amp is the "Deep" switch. It cuts the brittle/reedy high end and boosts the deep lows around 120Hz-400Hz (regardless of the harp's key). Those frequencies are right in the wheel house of the modern harp player's greasy grunt tone.

The new Deep circuit doesn't boost the overall gain or volume very much. Nor does it boost the harsh top end at all... the result is the amp does not overdrive much sooner with the deep boost engaged... but it does fatten the tone by a large amount. The circuit works similarly to an old fashioned "loudness" control, seen in vintage audio gear, but it is tuned for harp players and adds big bump in lower frequency roundness without out adding top end gain. This feature is a "must have" for players using multiple microphones.

If you need the extra volume a PA provides in a large venue, another great feature the Chicago chassis has is a "power tube and speaker" tone sampling circuit with a variable level line out control. Any XLR mic cable can be connected to the chassis mounted XLR jack so the amp can be plugged into your PA's XLR input. Max signal output through the XLR jack is about 800mvac so it can run another power amp if desired.

Face panel controls are: ON-OFF, Deep, volume, treble, bass, L.O (Line Out) level and fixed/cathode bias


--Bruce Collins, Mission Amps, Denver, CO bruce@missionamps.com

Monday, April 12, 2010

Playing Impressions: "The Chicago" from Mission Amps


Last night I took the new Chicago amp from Mission Amps to the Blues Jam my band hosts every other Sunday at Ziggies in Denver. This was the maiden voyage for the amp... the first time it has been gigged. Several harp players took it for a test drive. Here are my impressions of the amp:

VOLUME- The amp is loud, and that is important in a jam setting. As you know, there is very little volume discipline at jams. The 30-watt Chicago more than held its own against a stage full of guitarist with their jam enthusiasms. The amp has a line out for use if PA support is needed, but I didn't use it at all. The amp can hack it by itself.

When others were playing the amp I walked around the room and I could hear the harp well from all angles, even in the back. I had the volume on 5 (out of 12), and at that level the harp did not overwhelm the guitars, but stayed with them. Thirty watts driving an efficient speaker (102 dB @ 1 watt) will keep up.

FEEDBACK- Some harp amp builders will blow a lot of smoke up your ass about how feedback resistant their products are... as if they have some mystery trick for killing feed back. It's mostly BS. Feedback is a physical fact of the universe, and the ways to defeat it are not mysterious tricks.

When I played the Chicago amp last night it was remarkably feedback resistant. It started to ring right at 50 percent volume, but the amp was so loud at that point it was not an issue. It was WAY louder than I have been able to crank any of my other three amps before feedback in that room. No matter where I moved on stage I never once had to turn down because of squeal. Also, since I wasn't lined out (and wasn't in the monitors) the whole PA feedback thing was eliminated.

This amp resists feedback because Bruce Collins voiced it to roll off the highs starting at about 2K Hz. It will feed back slightly sooner in Cathode Biased mode than it will in Fixed Bias mode. The ceramic Cannabis Rex speaker is not beamy or shrill.

But.... feedback is a demon that lives in the air. Results may differ with a different time or place or weather or luck or whatever. All I can say for certain is the amp was impressive at Ziggies last night.

TONE- Cathode Biased amps have a characteristic sound that is saggier and crunchier than Fixed Bias amps. Cathode Biased amps sound more compressed. Fixed Bias amps sound stiffer and are generally louder. This amp has a toggle right on the panel that lets you switch from one mode to the other.

The amp also has a DEEP switch that steepens the tone curve for more bottom. Using these two controls gives you four distinct voices at any setting: You still have the Treble and Bass controls to dial it in. This makes the amp very versatile.

My favorite setting right now is Fixed Bias with the DEEP switch on. I have Bass at about 8 (out of 12) and the Treble on 4. Last night I played the amp with just a touch of delay from a pedal and no other effects.

The amp responds like a Ferrari. The sounds that come out if it feel as if they are directly connected to what you are doing with the harp and mic. You can go from Sweet to Nasty just by leaning into it a bit. A tight cup gives a very satisfying growl. The amp never feels like its straining.

The amp does not sound nasal or boxy. I did not hear any ghost notes or cone cry. The tone is complex and articulate, with lots of overtones swirling around. It cut through a loud mix like a machete, with a feeling of power and punch. I like the tone a lot.
Video - Dan Treanor, Cathode Biased Mode

Video - Dan Treanor solo, Cathode Biased Mode


Saturday, April 10, 2010

From Mission Amps: "The Chicago"

"The Chicago" from Mission Amps is ready. Master amp builder Bruce Collins designed it from the ground up to to be the most exceptional and economical mid-sized harp amp on the planet.

It is rated very conservatively at 30 watts. I've measured nearly 50 watts while playing. It is a 2x6L6 amp with a 50 watt power transformer. Here are some of the features:

-30 watts at only 34 lbs, in a Tweed Deluxe cab.
-All hand wired point-to-point by master amp builder. Beautifully crafted.
-Every finished amp rigorously tested by pro harp player. Guaranteed five years.
-Cloth-covered solid core wiring.
-NOS military-grade Paper in Oil capacitors. Dark, warm, lush tone.
-DEEP Switch for fatter tone.
-Switchable from Fixed Bias to Cathode Biased.
-Beefy 50-watt power transformer. Powerful bottom end.
-Optimized for bullet mics (including crystal) and Shure SM57 microphones.
-Separate Bass and Treble controls.
-Speakers broken in using custom harp-specific processes. Fat tone from the first note.
-“True Tone” Line Out XLR jack with level control. Perfect for PA or recording.
-One 12-inch Eminence Cannabis Rex speaker.
-Tweed Deluxe cabinet, finger jointed, solid pine with a furniture grade birch plywood baffle board.

I've played this amp extensively, and it sounds sensational. It is LOUD, with a complex, organic tone that responds easily to the pressure you put on the harp and mic. Goes from Sweet to Nasty when you dig in.

The regular price for this amp will be $1200. For a limited time the introductory price will be only $999.00.

I'll have this amp at the blues jam my band hosts at Ziggies in Denver on Sunday night. If you are in the area, I need your opinion. Please come play the amp and let me know what you think.




UPDATE: The amp is 20 in. wide, 16 in. tall, and about 8 1/2 in. deep at the top, from front to back. The exact weight is 33 pounds 12 ounces.

It sounds great at low volumes, particularly in the Cathode Biased mode. BTW, in that mode you can switch to 6V6 power tubes and a 5Y3 rectifier for the best sounding 15-watt harp amp you have ever heard.