Help Me Decide on a New Audio Project and/or Web Page

Last Update 1/11/98

New Photos of some of my stuff:

Photo 1 Shows the amp section of the Beast during power and distortion measurements. Volume control and input jack on front. Notice feedback cable connected to 1/8 in. jack on top surface to left of the input tubes.

Photo 2 shows the Complete Beast set-up. The power supply chassis and output transformer are simply laid on the workbench next to the amp and scope. Notice the X/Y trace on the scope. Not too shabby, eh?! This is at 100W output !!!
Ultramini 6j6/6aq5 guitar amp and Eimac 250TH in background.

Photo 3 Shows the guts of the amp section.
Not a whole heck of a lot in there!
Notice small muffin fans under each output tube.

Photo 4 is a shot of my Push-Pull 2A3 Amp .

Photo 5 is another shot of my Push-Pull 2A3 Amp .

Photo 6 is a shot of a DC coupled, Single-Ended, 2A3 amp I built a while back. Haven't made up a web page for it. In fact I've since recycled this Chassis for the Convertible SE SV572 amp. The 2A3 amp was unique in that it used a single stage choke loaded driver.

Photo 7 is a shot of a small Stereo SE amp I built. See if you can guess the tube line-up....
Notice the 7-pin mini driver tube. This amp puts out <1W, but it sounds soooo good....

Photo 8 is another shot of the mystery amp in Photo 7.

More Photos 1/11/98

SE45/2A3 is a shot of my newest SE 2A3/45 amp. This amp is using a 2HQ5 7-pin mini triode per channel as a single stage driver. How do you like the "Stone" finish ?

another SE45/2A3 shot.

yet another SE45/2A3 shot.

SV811 #1 is a shot of my Single Ended SV811-10 Amp . Notice that SV572-10's are instaled in this photo. I like the contrast of the Funky Green top plate in the blonde maple box.

SV811 #2 another view.

SV811 #3 another.

Here's a neat little push pull 1626 amp. It uses a single 12AU7 for both channels at the input. This is plate loaded with standard resistors, but cap coupled to some small signal interstage transformers for phase-splitting and driving the 1626's. The 12AU7 is not my favorite input/driver tube, but it seems to be the best match for this circuit. (tried 5687, 5965, 12AT7, etc...)

Here is a compact line preamp that I built using submini 6111 dual triodes. Topology is simple gain stage direct coupled to White Follower Output. One Knob is input selector, other is Volume.

Since my last update around 6/97 I've done quite a bit. Just haven't had the time to write it all up and post it here.

Now What.......?

Which of the following would YOU suggest I put on my site:

  1. 1. mini-line-stage using the stubby 5670

  2. 2. SE 812A amp using step-down transformer and cathode drive!!!

  3. 3. Push-Pull 2A3 amp using directly heated twin pentode driver.

  4. 4. Direct Coupled SE 2A3 amp - various driver options

  5. 5. Scarey SE Stereo amp using Eimac 250TH

  6. 6. Computer Modelling Vacuum Tubes using PSPICE, SABER, and MATHCAD

  7. 7. Circlotron-type bridge amp using 6AS7's .

  8. 8. Killer Guitar Practice/Light Jam Amp

  9. 9. ultra-mini guitar amp

I look foward to your comments/direction/encouragement/etc.

Email Bob. D. at

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This page, and all contents, are Copyright (C) 1997 by Bob. D.