Tuesday, November 3, 2009

Analysis: Fat Dog Model 2A Harp Amp

Rob Reynolds of Fat Dog Amps very graciously shipped me an example of his Model 2A amp for review. This article will cover the technical examination of the amp and some early playing impressions. This coming Sunday – November 8 – I plan to take it to the Blues Jam my band hosts at Ziggies in Denver. I invite any interested harp player to come on down, try the amp, and be part of the final review.

-Appearance: It is a good looking amp, decked out in all classic black. I took the amp to band practice last week, and the guitar player said, "Wow, what’s that?" The finish is sprayed on and seems nearly indestructible, and it looks and feels fine. In these photos you can see through the grill cloth to the speaker cut-outs, but that is only because of the camera flash. In normal light the grill cloth is completely opaque and looks cool. The amp weighs 39 lbs, and the carrying handle is quite comfortable.

-Design: The first thing that strikes you when you look at the chassis is that this is essentially a stereo amp. It has two discreet class A power amps, each with a Sovtek 6L6 tube and its own output transformer. The preamp tubes are a metal 6SJ7 and glass 6SN7, which give the amp a similarity to vintage Gibson and Masco amps. These are lower-gain tubes than you find in most newer amps. The rectifier is a 5U4

There is no need for a Phase Inverter since both power tubes run independently as single-ended amps. It is Siamese Twin Champs, kind of. A very interesting design concept.

-Build Quality: The amp looks and feels solid. This is not a cheapo home-built amp, by any means. Rob’s philosophy is to use quality off-the-shelf components to make a good custom harp amp at a reasonable price.

When you look at the chassis you see that philosophy in action. The wiring is all point-to-point, using good but not hyper-expensive parts. The power tranny is a Hammond 270FX. The caps are Xicon. He uses good ceramic tube sockets. The controls have a solid feel that I like (but the volume and tone knobs are too small and stick up too much.)

One cool feature is the two standby switches. You can put one amp on standby and play through the other, or switch them both on when you need more volume.

-Testing: Each mono amp produces about 3 watts RMS of clean power before clipping. When playing blues harp, of course, we love us some clipping so that is not a barrier. The amp puts out about 10 Watts total when cranked and clipping like crazy.

-Tone: Well, that is so subjective, isn’t it? I wrote earlier that this amp is like Siamese Twin Champs, and it does have that barky character of the Fender Champ, but with a lot more volume. It has that same cut-through-the-mix quality you get with a Champ.

The tone has a lot to do with the choice of speakers. Rob has gone with two Jensen mismatched speakers, an alnico P10Q and a ceramic C10Q. Both speakers have a smooth cone. It is true that mismatched speakers in a harp amp contribute to the singing overtones we all crave. However, I have always disliked reissue Jensen speakers for blues harp. These "Q" speakers are definitely better than the "R" Jensens I’ve tried, but I would still prefer Webers. Rob’s take on this is that the Jensens sound great after they are broken in. He may be right.

I've played the amp about 2 hours, and my early impressions are that it breaks up well, with a tearing across the leading edge of the notes when you push it. It has that Champ quality of sassy snarkiness, only not as compressed.

-Price: Rob sells the Fat Dog 2A harp amp for $850.00. You can step up to a 2x12 configuration for only $25.00 more. That seems like a great bargain for either amp. The price is at the entry level for custom harp amps, but the product is way more than your typical 5F1 Champ clone.

Please check back in a few days for a full hands-on review of the Fat Dog Model 2A harp amp in action.


CR said...

Rick, 10 watts total output or 10 watts for each amp? Has he tried playing with a 1-12" & 1-10" setup?

Christopher Richards
Twin Tone Harmonica Microphones

Rick Davis said...


The amp produced 10 watts total output when dimed.

I don't know if Rob has tried a 1210 combo. The one he sent me is 2x10.

Dude, come on down from Greeley and give this amp a try. I'd like to hear your impressions.