Woo-Hoo Show-Off Time

[rcrmck]

I just finished my very first conversion!
It's a modified hammond tone cabinet 6v6 amplifier running 1940's electrodynamic speakers as a Bi-Amp. Very simple, the unit will operate with input levels anywhere from a preamp out to a speaker out on virtually everything from my vocal mixer to my Coliseum 300. I get what can only be described as a "shimmer" in the sound when pushing it from mid-low to moderately high volumes when treble frequencies are emphasized. I mean this thing really sings! Perfect for my rockabilly style guitar.

As you can see, I built the cabinet myself out of solid pine, with a hardwood plywood soundboard. I planned to cover it with vinyl, but when I got to the fabric store they had this upholstery fabric for only $2 per yard, so I swtched it up at the last minute. I think it gives the amp a high-end look.

The plan is to build a lookalike to this one, using 2 more of the same speakers, with a hoffman AC-30 design I'm building as the 'main amplifier' that will power this one when I need that extra volume.

[GibsonLover]

That's a pretty creative re-purposed amp. Which Hammond model is it? Can you explain the bi-amp feature a little more? It looks like you have enough iron there for PT, choke, and two OT's? I love stereo amps, and have recently thought of doing a custom tri-power chassis, for a Main + stereo / triple mono power. You can get a lot of noise out of three low power SE amps...That looks like a nice chassis to start with. The fabric looks pretty retro too.

[rcrmck]

Thanks!
The amp was marked H-Type, and I believe it came out of a F-40 tone cabinet, although I got the amp incidental to an unrelated C/L purchase, so I don't know. I am NOT an expert in electronics at all, so much of what you said went flying right past me, but I got the making of a bi-amp system for guitar from bass amps I used on stage. I used a coliseum 300 which had a frequency adjustable bi-amp out feature that I plugged into a slave power amp. So, I wanted to do that with a guitar. The idea being I run through a preamp and then I send the signal to both a main amplifier (the AC-30 I'm building) and a slave power amp (this amp you see here) that caries a differrent tone. I started with the slave power amp because the amplifier was almost exactly how I wanted it already, and I needed to do only a couple modifications to the G-G input. The match to this, the AC-30, is the more complex in that I am building it 100% from scratch, and adding a variable bi-amp out from the OT to the over-the-counter design I got from Hoffman.
But, like I said I'm no expert. This was my first DIY. When I saw the amp I thought it had way more transformers than needed, and even after staring at the schematic, I still can't figuire out whay so much. And for only a 20 watt rating? But it's sound quality I was hoping for, and I have to admit it came out great.

[tubeswell]

when I got to the fabric store they had this upholstery fabric for only $2 per yard, so I swtched it up at the last minute. I think it gives the amp a high-end look.

I do my scratch-built amps the same sort of way (in fabric upholstery). The chics dig the 'do.

[booj]

manatbootiful

[rcrmck]

Just a little bragging update...
So the AC-30 copy idea was scrapped due to a personal lack of skill, but I was able to salvage the project into what is now my goto amp! As you can see in the picture, I built another matching cabinet for the other two 12 field coil speakers. Now all four are run by the Hammond poweramp conversion. Also I took an old Univox SS amp, and boxed up into a matching head cabinet. What I have now is kind of a hybrid where the tube poweramp is run by the Univox SS amp. I got good reverb, equalizer, onboard effects, and pedal switching. It sounds great, and I'm really happy with the looks. I'm not a "high gain" player, but those power tubes will overdrive nicely with the volume up.

[mooreamps]

Very nice work... Simple, portable.. Just plug in and turn on... Probably has a great tone as well....


-g