The Amp Garage

What tube testers are you guys using and what parameters are they measuring?

I had some time with my friend's Amplitrex yesterday and tested some new JJ ECC81's in the ways described above. I let the tubes cool completely between each test. The first test involved turning the heaters on for 1 minute and measuring both sides immediately. For the second test I turned the heate...

Hi Martin, Thanks for your reply. In general I notice a 1.5 mA to 3 mA difference in plate current after letting a tube like a 12AU7 or 12AT7 flow current continuously for a couple of minutes. This does not happen with lower current preamp tubes like a 12AX7. Tomorrow I'll be around the Amplitrex an...

I have a question about this tester. I've noticed when testing power tubes and higher current preamp tubes like 12AT7's, 12AU7's, and 12BH7's that the tube needs to be flowing current for some time before it "settles in" to a stable plate current. For preamp tubes like those mentioned above about 1 ...

Thanks RP!

Thanks for all of the replies and input. I figured the CE turrets were made by Keystone but I guess not. I took the board to work today to try my luck with the Metcal soldering station there. By the time my coworker got the turret hot enough to flow some solder it melted the fiberglass board materia...

For the life of me I can get solder to stick to the turrets I got from CE. Not sure if maybe I got a batch with bad plating or maybe my soldering skills have gone south. Every joint on the turrets looks like a cold solder joint and the solder just kind of blobs up on them. I have a decent Weller sta...

I've been using my ODS 124 build for bass and it sounds great with the eq set to "jazz."

Thanks guys!

I'm recapping a friends Ampeg V4b. In the filter node for the screen supply there is a pair of 40 uF filter caps connected in series without the usual bleeder resistors from the junction of the caps to both B+ and ground. Would there be any reason not to add them? The designers at Ampeg seem pretty ...

Thanks for the reply Steve. Looks like it is an input jack! I don't know why I didn't check that earlier.

When all volumes are turned down the amp is quiet. The Vib/Trem channel is quiet when turned up on it's own. The buzz Normal channel strangely gets quieter in the first part of the rotation of the pot and louder in the second part of the rotation. No Trem ticking in the normal channel. The Top Boost...

Hi Guys, My bandmate asked me to look at his Korg-Era AC30TB. Over time it has developed a loud buzz/hum and you can hear the tremolo ticking, especially in the top boost input. I changed all the filter caps and replaced all the tubes with known good ones hoping the problem would be something easy b...

Thanks for sharing and taking the time to post your schematics over here!

I built a Dumble #124 Clone (thank you amp garage!) and use a cab with an early Peavey Black Widow 15." This setup really leaves nothing to be desired. It's like a sweeter sounding Fender Showman with better EQ options for steel. I play mostly clean non-pedal. The Dumble clone has tons of headroom a...