Sunday, November 24, 2013

New Memphis Mini Amp website

Click on either image to go to the new website.

Friday, November 8, 2013

Review: Squeal Killer anti-feedback pedal

Let’s cut right to the conclusion:  The Squeal Killer works at least as well as the Kinder AFB+ at its core function of reducing feedback.  But there are a few important differences and caveats.  Read on…

The Squeal Killer has no adjustments at all.  In fact, it doesn’t matter which jack you use for microphone in or out.  The jacks are not even labeled.  The power supply is hard-wired to the box so you cannot run it with a common 9-volt power source, which could damage it.  Setup is a no-brainer.

I didn’t open up the pedal because doing so will void the warranty, and I’m sure the creators of the pedal want to preserve any trade secrets in the circuit. 

The SK pedal is dead quiet and does not introduce any noise into the signal that I could hear. 

For this review I used my Mission Chicago 32-20 1x12 amp in fixed bias mode.  It makes 35 watts and is very loud.  I typically play this amp on loud stages with no PA support.  I compared the performance of the SK to the Kinder AFB+ and to the amp with no anti-feedback device.  The harp mic I used was my 1959 Shure 440SL with the in-line volume control removed.  The review was done in my music room in my house.

I used a sound level meter to confirm my subjective judgments, but I relied on my ears to form my conclusions.

First, I played though the Mission amp with no pedals for a while to get a baseline level and tone.  I am always impressed with the tone and power of that amp.  With the amp on 5 (out of 12) it was barely edging toward feedback and sounding awesome.  Let’s call that the baseline level.


Next I plugged in through the SK pedal.  The first thing I noticed was that the pedal attenuates the signal.  The amp was not as loud on 5 as it had been without the pedal.  I was immediately skeptical that the SK pedal was no different than a lower gain tube in V1, which will reduce your loudness allowing you to turn up more but likely getting feedback at the same ultimate amplitude.

But as I cranked up the amp it got to the baseline level at about 7 with no feedback, and I was able to crank it to 9 before it started barely tipping in to feedback.  The amp was louder than it had been on 5 with no pedals.

Next was the Kinder AFB+ pedal.  This pedal does not attenuate the signal as the SK does.  I was able to crank the amp to 7 before hearing a little ringing, which is the conventional wisdom for the AFB+.  It is known for giving you about two extra notches on a loud amp.

On 7 with the Kinder pedal the amp was about as loud as it was on 9 with the SK pedal.  At these levels feedback was slightly better controlled by the SK pedal, and the sound was more natural.


The Kinder AFB+ is known for sometimes impacting the tone of your amp.  Many players say it adds a bit of crunch.  To my ear it is a small trebly rasp that is not really annoying but is there.  The SK pedal has none of that.  It sounded closer to the true sound of the amp,

I think the amp sounded best by itself, but it got louder sans feedback with either pedal.


It is common knowledge that replacing the input tube in your amp with a lower gain tube changes the slope of the amp gain, making it less steep and easier to manage.  The amp will not explode into sudden screaming feedback so abruptly.  The SK pedal has that effect but it goes farther:  It reduces feedback potential at the margins of higher volume.  It allows you to crank your amp more toward the “sweet spot” in the power tubes so you can get improved amp tone AND reduced feedback at higher levels.

Based on what I heard today I’d give the Squeal Killer a recommendation.  It certainly deserves to be in the conversation when discussing anti-feedback devices.  It gets extra credit for simplicity and lower price.

The Squeal Killer is available online from Rockin’ Ron’s Music 4 Less.  They offer a 20-day return policy if you are not satisfied.  I’ve dealt with Rockin’ Ron’s in the past and he has earned a reputation for excellent service and reliability.  That is part of my recommendation for this product.


-The SK pedal is advertised as allowing you to crank your amp to 9, and that is true but don’t expect your amp to be as loud as it is without the pedal.  The increased headroom you get before feedback is not as dramatic as they make it sound, but it is about the same increase you get with the Kinder pedal.

-It bears repeating:  The increased headroom you get before feedback is NOT dramatic but it is useful.  This pedal is not a magic bullet. 

-This review was done in a certain room on a certain day with a certain player and a certain amp.  Your results may vary.  Feedback is a demon that lives in the air and it is very unpredictable.


Several readers have asked about the readings on the sound meter, Let's not get hung up on the numbers. My review was about playing impressions, it was not a lab test. The sound meter was there only to confirm my subjective judgment that I had the pedals at equal loudness, given that the SK pedal attenuated the signal and made comparisons of the volume knob position meaningless without a baseline measurement. I'm sure somebody will come along and do a more scientific test of the SK pedal.

Friday, June 21, 2013

Scott Woerner - Harp Mechanic

Meet Scott Woerner (pronounced "Warner"), Denver harp player, motorcycle rider, tech guru, and ace harp mechanic. He does all the harp work for Nic Clark, Al Chesis, and me, among others. 

I gave him an MBD in E with a failed reed in blow 4, and he replaced the reed, tuned and gapped the harp, and re-sealed the comb. It plays like buttah now; responsive and balanced.

Scott's fee for this was so low it was astonishing. I'll leave it to him to quote you a price. I can tell you it was a fraction of what you would expect, and the finished product was exactly what you expect from a pro harp mechanic.

Scott's email is swoerner at msn dot com. He gets the Blues Harp Amps seal of approval.

Thursday, June 13, 2013

We're In!

The Mile High Blues Society has been accepted as an affiliate of the Blues Foundation.

Monday, May 20, 2013

Bassman tone

Here are three videos, two different players, playing my Bassman amp.  At Ziggies Sunday Blues Jam in Denver on May 19, 2013.

Saturday, May 18, 2013

My 1964 Marvel Tube Amp is for Sale -- $200

***  SOLD ***

These amps were made by Multivox in New York City, the same factories that produced the legendary Premier Twin 8 amps.  It shares some circuit features with the Twin 8, including the single 7591 power tube.

The 7591 in this amp is a vintage Multivox branded tube, almost certainly the original.  It checks out good and sounds great, so no need to replace it.  The preamp tube is a NOS Westinghouse 12AZ7.

The original speaker had some wear so I replaced it with a reconed vintage Oaktron alnico speaker from the mid 1950s.

The amp was serviced by Bruce Collins at Mission Amps in Denver:

-Install grounded power cord
-Remove the "Death Cap"
-Install cathode bypass cap on the power tube. This gave the amp a bit more punch.
-Modify the power supply.
-Test all tone caps for leakage.   Replaced as needed.
-Test all circuit voltages.
-De-oxidize the tube sockets
-install speaker jack
-Install line out

The amp produces a bit more than 6 watts at clipping.  It sounds amazingly big and warm for an amp with a 6-inch speaker.  The small alnico speaker gives it a nice compressed juke joint crunch.  When the amp gets warm it puts out that great vintage tube amp smell, too.

I’ve gigged it and it performed flawlessly.  However, I sell it as-is and make no warranties.  Carry this little less-that-10-pound amp and a cable for the line out and you are ready for anything.

Here is a brief video of the amp playing though a PA via the line out jack.

I’ve had the amp for six months and love it, but it is time to pass it along and move on to the next project.

The price is only $200 plus pro packing and shipping via UPS.  Contact me at

Thursday, May 16, 2013

For Sale - 1960s Danelectro Reverb Tank

Nice tone!  And I dig the production values...  "Unit ON!"  This vid should go viral.

Larrystick is looking for offers on this very cool vintage gear.  Contact him at:

Saturday, May 11, 2013

My 1962 Premier Twin 8 amp is for Sale - $500

** SOLD **

1962 Premier Twin 8, the iconic amp from the heyday of vintage blues harp tone.

This amp is a solid player, not a collector's piece.  There are a couple of scuffs on the amp, as you can see.  This bad boy has got some mojo.  The circuit has been gone over by ace amp tech Bruce Collins of Mission Amps.  Both speakers have been re-coned, one original and one period correct.  

These are legendary amps, and it is time to hand if off to the next player in search of a legend.  $500 plus shipping, professionally packed and shipped via UPS.  Contact me at

1970 Fender Bantam Bass Amp

This rather peculiar amp is highly coveted by some harp players and amp collectors.  Nic Clark has one and he played it at his gig last night with Bad Brad & The Fat Cats at Ziggies.

The speaker is a flat trapezoidal thing made of white styrofoam, from Yamaha.  It blew up a lot so it is rare to find one of these amps with the original speaker.  The circuit is the same as the Bassman 10 of the era:  30 watts from two 6L6 power tubes and a tube rectifier.

Nic was playing a Shure 545S mic.  A very interesting combination.  The tone was good.

Monday, May 6, 2013

The Delta Sonic Amp at the Blues Jam

Gregg MacKenzie and Nic Clark show off their old school chops at The Mile High Blues Society Jam at Ziggies in Denver, Cinco de Mayo, 2013.  They are both playing through my rig:  Mission Delta Sonic Amp and 1959 Shure 440SL microphone.

Wednesday, May 1, 2013

Mission Delta Sonic Amp - Line Out Test

This is the 15-watt Mission Delta Sonic blues harp amp. The first clip is the amp by itself, and the second clip is the amp plus a line out to a PA system: Mackie 808M and Mackie speakers - typical bar band PA system.

I'm using a touch of delay (MXR Carbon Copy) for slap back. There are no effects in the PA channel. The amp is EQ'd in the PA channel with HIGHs and MIDs rolled off and the LOWs boosted.

I played the amp at a gig with a loud blues band last Saturday, and the line out is the big problem solver. Once you get it dialed in it sounds huge. I even had a bit in the monitors.

The amp has a 12AY7 in the preamp socket, and two JJ Tesla 6V6 power tubes. Bruce at Mission Amps made a couple tweaks to the tone stack since the last time you heard the amp. This is the final configuration. 

Monday, April 22, 2013

Nic Clark Solo

This is from the Mile High Blues Society Jam at Ziggies in Denver last night. In this clip Nic does a good job of illustrating a couple of the soloing strategies we teach at our "Blues Jam 101" seminars. He starts out simple and repetitive, with mostly single notes low on the harp. Through the solo he builds tension by moving up the harp and playing more double stops and chords. He does some interesting things here.

Nic is playing a Mission 32-20 1x12 amp that Bruce Collins built for a good local player. He is using my 1959 Shure 440SL microphone and zero effects.

The jam was packed! Great music and great people. All jams should be like that.

Friday, April 19, 2013

New "Family Photo"

Clockwise from upper left: 1962 Premier Twin 8, 1970 Fender Champ, 1964 Marvel, Mission Delta Sonic, Mission 32-20, 1991 Fender Bassman. 

And right in the middle is the Electro Harmonix 44 Magnum.

Monday, April 8, 2013

Blues Harp Solos - Mission Delta Sonic Amp

Gregg MacKenzie and Nic Clark at The Mile High Blues Society Jam at Ziggies Saloon in Denver CO, April 7, 2013.

Saturday, April 6, 2013

The Delta Sonic from Mission Amps

A new small harp amp from Bruce Collins at Mission Amps - 15 watts from two 6V6 power tubes, with a single 10-inch speaker in a tweed "Harvard" cab.  In this video I'm using an MXR Carbon Copy pedal for a touch of slap back.

Friday, March 29, 2013

1949 Gibson BR-9

These were originally packaged and sold with a Gibson lap guitar. Very cool; the amp has two 6V6 power tubes and it uses an interstage transformer (not a phase inverter tube) to drive them in push-pull. It makes maybe 10 watts. 

The cab is a little trapezoidal thing, with a 10-inch field coil speaker. One knob for volume, no tone control. It is similar to the 1947 Gibson amp I once had. It has a nice old school tone.

Wednesday, March 13, 2013

New Small amp from Mission Amps

This is the new small amp from Bruce at Mission Amps, sitting on the bench in his shop. The amp is now down in my amp room. Bruce asked me to thrash it out for a couple weeks.

A few design decisions have been made:

-It will come in a tweed Harvard cab, as you see in the picture.
-The speaker will be the 10-inch Eminence Lil Buddy.
-The power tubes will be two 6V6,
-The preamp tube will be a 12AY7.
-It will have a line out.
-It will sell for under $900.

It makes an honest 15 watts and sounds great. It weighs in at 24 pounds.  I'll put up some videos over the next few days to show how it sounds. I also plan to take it to Doc Brown's Jam at Ziggies in Denver on Sunday to let other players try it and get their opinions.

One thing the amp does not have is a name. Bruce wants to hear your suggestions. The amp is cathode biased for some mellow crunch and warm sag tone. You got a name for that? Let me know and I'll pass it along.

Tuesday, March 12, 2013

Watts Revisited

Somebody asked me in another forum why I use the term “watts at clipping” to describe the power an amp makes.  I thought I’d devote a new blog post to this topic.

It may surprise you to know there is no hard and fast formula that amp makes use to calculate exactly how many watts their harp amps make.  In 2009 I researched an article I was writing on this topic by contacting all the big harp amp makers at the time to find out how they arrived at their wattage claims.  Some of these amp makers were quite annoyed that I even asked the question.

I believe we need a standardized method for calculating amp power so the numbers are meaningful and consumers can make rational, informed decisions.  Wattage numbers in amps are like horsepower figures in cars.  There is a powerful incentive to fudge the numbers upwards – higher than your competitors – because many buyers are greatly influenced by it.

You've probably seen wattage claims for boom boxes or car audio or computer speakers that seem, um, unlikely.  They sometimes claim hundreds of watts when the truth is a small fraction of that.  Harp amp makers have been more restrained in their numbers, but still there is no real standardization.

Those of you who like vintage hifi gear will recognize this phrase:  110 watts RMS per channel @ 8 ohms from 20 to 20K Hz with .1% THD.  I found that harp amp makers borrow parts of that formula to arrive at their wattage spec.

This is what they do:  They drive the amp with a test tone – a sine wave – and measure the AC output at the speaker tap by watching the waveform on a scope.  You may have opinions about what the proper method should be, but that is what they actually do.

One problem is that the frequency and amplitude of the test tone is not uniform (and certainly not announced by the amp maker) and it can make a big difference.  Another problem is the amount of deformation they tolerate in the wave form at the point they claim as their wattage number.  In other words (as in the hifi formula), how much distortion is included in the number?

This is where the question arose in the other forum:  What the heck is wrong with distortion?  We love distortion in our tone, right?

Indeed we do, but for the sake of arriving at a meaningful wattage number that allows us to make real comparisons we have to stipulate the level of distortion in the test.  The easiest and best way to do that is to measure the amp’s power at the point that the sine wave begins to clip.  That is a very good indication of the amp’s true strength.

Can the amp make more power beyond the point of clipping?  Sure.  But depending on the design of the amp the distortion (the deformation of the sine wave) can start to sound unappealing pretty quickly.  Amp makers could just crank everything to the max and report that number but it would be unrealistic and meaningless for musicians, and there are lots of ways to juice the max number.  We want to know:  How much clean power can the amp make?  How does it compare with other amps?

Here is what I am suggesting as a standard for harp amp makers:  Drive the amp with 150mvac@130Hz and measure power as peak clean voltage into the appropriate true non-reactive load.

Is it a perfect formula?  Probably not, but it is not meant to be.   We need to insist that amp makers use a standard, uniform and verifiable method of calculating their wattage claims, and this method is a good place to start that conversation.

Monday, March 11, 2013

Blues Harp Solos

Here are three short video clips of blues harp solos from the Mile High Blues Society jam at Ziggies in Denver, Mar 10, 2013. The players are Ronnie Shellist, Gregg MacKenzie, and Nic Clark,

I brought two amps to the jam: Bassman and Mission 32-20. Just for fun, can you guess which player is playing which amp? No pedals or effects (not even delay) on either amp.

Ronnie Shellist at the MHBS Blues Harp Workshop

Here is a a snippet of Ronnie Shellist at the MHBS Blues Harp Workshop yesterday, discussing how he likes to mix amp tone with the vocal PA mic.

Ronnie is playing through a '57 Supro he found at a thrift shop for $79. The guitarist on stage with him is Matt Hendricks, a very fine blues player and singer who recently moved from Chicago to Denver.

Thursday, February 14, 2013

Harp Mic Test

I compare the Front & Center mic, 1959 Shure 440SL mic, and Shure SM57 mic with Bulletizer from Greg Heumann at

Whadda ya think?

Wednesday, February 13, 2013

Monday, February 11, 2013

Nic Clark on Chromatic

Nic is playing into a Mission Chicago 32-20 amp using a Front & Center microphone.  This was at The Mile High Blues Society Jam at Ziggies in Denver on Feb 10, 2013.

Tony Smith playing into a Fender Bandmaster amp

With the Delta Swamp Rats at the Blue Rooster in Sarasota, FL.

Thursday, February 7, 2013

2 amps - Premier Twin 8 and Fender Champ

The Premier amp is as original as I can make it.  The Champ is highly modified, with a 10-inch speaker, bigger transformers, and other tweaks.  You can find the details here:

Wednesday, February 6, 2013

Essential Music Theory for Harp Players

Essential Music Theory for Harp Players 

Excellent.  Written by a contributor at Adam Gussow's blues harp forum.

Saturday, January 26, 2013

1962 Premier Twin 8 vs 1964 Marvel Amp

Two early 60's amp made in NYC by Multivox.  They share similar circuits, with 7591A power tubes and 12AX7 preamp tubes.  The Twin 8 has two 8-inch speakers while the Marvel amp has a single 6-inch speaker.  They both make about 6 watts of power.

Both amps have been worked on by Bruce Collins at Mission Amps.  Both had grounded power cords installed and worn components replaced.  Two tone caps were changed on the Twin 8.

Friday, January 18, 2013

Nice Tone! Greg Heumann's K-Zoo Amp

This video was sent to me by a friend.  This is an old Kalamazoo amp  retrofitted by Greg Heumann at Blows Me Away Productions.  Very nice.

Tuesday, January 15, 2013

My Latest Project - Premier Twin 8 amp

The Premier Twin 8 is an icon of vintage harp tone, known for it's colorful crunchy tone.  It arrived yesterday and needs a bit of work.  It still has the flimsy power cord and 2-prong plug.  The pilot lamp is burned out.  And, it needs a general going-over by a good tech.

The power tube (7591) and the rectifier look to be original, as do all the tone caps.  The preamp tubes are Tung Sol 12AX7.  The layout and tone are similar to the vintage Marvel amp I rehabbed recently.  They were both made by Multivox in the early 60s.

It is a small bugger.  I will put up a photo later with something to reference its size.

I'll report back as this project progresses.  This should be fun!

(That's a regular Mississippi Saxophone harp case next to the Twin 8.)

First test recording

Monday, January 14, 2013

Perfect Amp Tone?

In this video Nic Clark is playing my Mission Chicago 32-20 amp, with zero effects, not even delay.  To my ear this is perfect amp tone:  Warm and full with a bit of crunch.  It gets some sag and sings with overtones, although that does not come across as well in the video as it did live.

The tone is not shrill and the grit is not ratty or overdone.  It is not boxy or nasal or muffled.  Perfect.

When I say "perfect" I mean it is my ideal harp tone.  It is what I had in my head when I was helping to design and develop this amp.  I know full well that amp tone is subjective and there is no such thing as perfect tone, but if you ever wondered what perfect tone means to me, this is it.

Thursday, January 3, 2013

Blues Harp PA Test

Goofing around with gear; trying to get a gritty sound though the PA.

I set up my PA and played through it using a Shure SM57 mic. The PA is a Mackie 808, the PA we use at clubs that do not have a sound system. I used Mackie C200 speakers.

What I listened for was that slight tearing on the front edge of percussive notes you hear with a nice tube amp. That is the "grit." So I just played the same things over and over and listened.

First I played directly into the PA with everything set flat and the channel trimmed so it was not clipping except on the loudest transients. The tone was as you might imagine: Pretty dry.

Next I cranked the channel trim all the way up and rolled back the master volume. Better, but still not very tube ampish. It distorted but not with the same nice sound you get from a good harp amp.

Then I used a Presonus Tube-Pre between the mic and the PA. I cranked the Drive control and rolled back the Gain control on the Presonus, and backed off the channel trim on the PA a bit. It still clipped the PA channel most of the time.

The preamp did give a bit of that sound. The sound does not have all the moving parts you hear in good tube amps, but if what you want is grit it did have some of that. I thought it sounded pretty good.

I don't think they make the Presonus Tube-Pre any more, but you can get the same effect from an ART Studio Mic Preamp which sells for less than $30.  I've seen Kim Wilson use it.