Recent Posts

41

Tube Amp Building - Tweaks - Repairs / Re: Champ-ish "pocket"-amp

« Last post by printer2 on January 22, 2026, 12:55:15 pm »

Using a 12V laptop brick and 0ne of the 45-390V dc boosters to supply a 12AX7 and 6V6. I did up the heat sink on the module and have it outside the chassis for cooler air. A 6K6 (with 12AX7 in series with it along with a resistor parallel with the 12AX7) or a 12AQ5 would play nicely with the module unmolested. I squeezed everything in as small a cabinet as possible, thinned the wood down, 8" speaker just fitting inside. Have a p-p switch on the treble pot and the tone stack goes in between a Marshal and Fender response. Otherwise just a SE Champ type circuit. Debating on adding a delay board or a Digilog reverb yet.


Mostly play through the Blackface position as it makes the amp sound less boxy in the small cabinet (9.5"x9"x6") but has a speaker out jack in case a larger speaker cabinet is kicking around.

42

Tube Amp Building - Tweaks - Repairs / Re: Favorite 6AQ5 SE and PP power sections?

« Last post by printer2 on January 22, 2026, 12:49:39 pm »

Oops, wrong thread.

43

Tube Amp Building - Tweaks - Repairs / Re: Princeton Rev AA1164 Rectifier + Filter Cap Question

« Last post by ac427v on January 22, 2026, 07:49:44 am »

I like to use the Allen Amps system. A separate 22U cap mounted on a terminal strip for the first (reservoir) capacitor. The power transformer center tap is connected directly to the reservoir cap ground. A jumper connects them to the cap can ground. That helped with the reverb hum I was having in my Princeton Reverb builds.
Also helpful was using a 220u cathode bypass cap on the reverb recovery triode. I suggest buying one with your next parts order just in case.

44

Tube Amp Building - Tweaks - Repairs / Re: Battery powered germanuim transistor travel amp

« Last post by roarshock on January 21, 2026, 10:58:40 pm »

That's cool! There's an Italian cat that posts to reddit every once in a while that makes amps out of old transistor radios. I like small amps, so keep them coming!

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Tube Amp Building - Tweaks - Repairs / Re: Fender 6G8 hum

« Last post by AlNewman on January 21, 2026, 08:28:32 pm »

Maybe the power amp caps are weak?  Maybe it's time to focus again on a tube change.  The fact that one of the screen resistors is off spec is interesting.  You could pull 2 tubes, one on each side of the output transformer, check for noise, and then check  the other 2 tubes the same way, and see if you can isolate where the noise is coming from.
The screen resistor should probably be replaced either way.

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Tube Amp Building - Tweaks - Repairs / Re: Laney Amp - 220V to 120V

« Last post by Joe6v6 on January 21, 2026, 08:04:09 pm »

Remove the jumper between 0 and 120. Put a jumper between 0 and 0. Put a second jumper between 120 and 120.

      That did it! Thank You   

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Tube Amp Building - Tweaks - Repairs / Re: Battery powered germanuim transistor travel amp

« Last post by Banjan73 on January 21, 2026, 08:02:36 pm »

Oh!
I found a picture of the internal of the amp:

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Tube Amp Building - Tweaks - Repairs / Re: Battery powered germanuim transistor travel amp

« Last post by Banjan73 on January 21, 2026, 07:56:35 pm »

Heres my collection of home built (minus the "two channel class A" thing) so far:
Threads are:
-This one
-Champ-ish "pocket" amp
-High gain two channel EL84 guitar amp

49

Tube Amp Building - Tweaks - Repairs / Battery powered germanuim transistor travel amp

« Last post by Banjan73 on January 21, 2026, 07:51:50 pm »

Hi.
Here`s one more project I had the last years. This is not a tube amp, so please delete this if it`s not relevant/aloud here ;-)
The background on this amp was that I bought myself a travel guitar. So again, when traveling with my motorcycle, I needed a small amp powered by batteries.
I once built a clone of the "beano boost" with a Germanium transistor and I love the sound of this one.So therefore, this time I decided just to use the amplifier of a old radio. I ended up buying an old Norwegian "Radionette kurer transi" from 1958 which uses OC74/OC75 transistors, and slaughtered it (with a little tears in my eyes, off course). 
I found the schematics on the internett, and it`s attached. The amplifier part is circled. Looks almost similar to a tube amp?
Anyway, the connections where pretty easy. The loudspeaker is the one from the radio. So I built a cabinet to this thing. The input jack works as an on/off button just like an effects pedal.
Sound? Pretty cool. With a tube screamer in front, thisone screams pretty good! Nice practice amp.

50

Tube Amp Building - Tweaks - Repairs / Re: Blues Jr Hoffman Circuit Adding Reverb

« Last post by stratomaster on January 21, 2026, 07:04:56 pm »

You would also need to create a low voltage power supply for the IC to power to Reverb circuit.

The meat control can be deleted by simply not populating it and replacing it with a wire. Refer to the official Fender schematic.