The Amp Garage

I've been gone from this group for awhile and really enjoy the topics and folks here! I have made 30 amps so far in my small amp "business". I got the idea to make my eyelet boards out of a clear plastic for two reasons. 1. is that they looked cool and B. I can see the two power supply wires undern...

I've been gone from this group for awhile and really enjoy the topics and folks here! I have made 30 amps so far in my small amp "business". I got the idea to make my eyelet boards out of a clear plastic for two reasons. 1. is that they looked cool and B. I can see the two power supply wires underne...

I use Heyboer output transformers sourced from Weber all of the time. Sometimes I use Weber power transformers and they have been fine too. TA has been really going out of his way to give us good service! I ordered a 12 inch Blue Dog and a Heyboer 40 watt transformer set. All built to order and I ha...

JoeCon, I'll be glad to post the schematic. I find the Vox amps to be a bit too high gain for a non-feedback type of amp. Reducing the level between stages and lowering the plate resistor from 220K to 100K on the last stage before the PI goes a long way to stabilizing the unit. Since the Schematic i...

I know the topic is about the mixed bias later versions but I can vouch for the wonderful sound of the original design. It's grounded cathodes, AC30 Top Boost preamp, no power amp feedback just like the schematic posted. I did adjust the gain structure to clean it up just a bit and make it more stab...

pdf64, I think you are right.

However, if I've misread your question, you are trying to measure the plate current through each tube. 6V6s at about 420 volts should have the resting current at about 20 mA at about 60% of the plate dissipation. Reading each tube with an RMS type of meter will give you the most accurate (if that's ...

Hmm...if you have 1 ohm 1% 2 watt resistors in series with the cathode to ground, you can measure the resting (no signal) plate + Screen current through the tube. use your digital multimeter on the millivolt scale (in a range to read less than 100 mV). Read the voltage across the 1 ohm resistor and ...

Well, I did find them and they work fine in jschem. False alarm! My aha moment happened.

I hate to appear computer ignorant but I can't find the files with the schematics in this forum. They just appear to be messages (text). I did download Jschm for my Mac to view the schematics but can't find the attachments. I know I'll have an aha moment but can someone help me locate said files?

It seems to me that not long ago (before internet sourcing of parts and resurgence of tube circuits) it was difficult and expensive to get 450 and 500 volt electrolytic capacitors. If you looked in the electronic magazine ads for parts, you found tons of "photoflash caps" for sale on the surplus mar...

Just returned to the Antek web site. The only 320 volt transformer is a 50 watt unit. They do have a 275 X2 100 watt unit (out of stock naturally) for $34 but it has no 5V winding. I'm OK with the SS rectifier and may do a version of a Rocket,mixed with a Matchless DC30 to see what it sounds like. I...

350 Volts per secondary. 700 total Pk to Pk. So 700 divided by two is 350 (duh) X 1.414 give 494 volts after rectification. Needed 325 and didn't know then (three years ago). The transformers are still on a shelf (just looked at them to get the secondary voltages.

I have purchased three transformers from them in the past before I knew how to figure the final rectified and filtered voltage under load. Unfortunately, no matter what configuration I chose, the end voltage was well over 500 volts, too much for even the JJ 6L6 and 6V6. I don't quite understand why ...

the speaker in a Charlie Christian era EH-150 was very likely a field coil speaker. My experience with them (in a late 40s Leslie and a couple of old amps) has been that they lack any real bass and have less magnetic field than a PM speaker. If you don't like the Weber speakers, then a vintage P12R ...