AMI B low volume

Am putting my AMI B back together. Finally the selection, credit circuits and mech seem to be working great (at least on the bench!)

However, volume is at best medium when cranked up. I Have the Black R-22 amp with the plug-in volume control that mounts higher in the box. Sounds clear, no distortion, just low. I have the original cartridge installed (at least the one I got it with). Still on 78's. It's a Shure with the spike -type needle. I did purchase the recommended replacement Pfanstiehl 51-3 cartdridge/stylus, but have not tried it out yet. All tubes check out good on my (admittedly crappy) Lafayette tester. I've replaced only the electrolytic caps.

I recognize it could be "a whole bunch" of possible problems, but can anyone give me a list of the "usual suspects"? Where does the "experienced guy" look first? Thanks!! Carl.

CG,
"First"--change ALL other caps--then check resistor values--
Also--check that the Volume Control is correct (35k ohm, I think ?)
Ron Rich

Thanks Ron. I'll do all caps. Just ordered a complete kit.

If you don't get all the wax/paper capacitors changed, you'll probably be changing a power transformer soon!

OK, I completely recapped my AMI B amp, and replaced a few resistors as well. The amp, after a couple minutes, sounds great and volume is now fine too. However, it does take maybe 2 or 3 minutes to "warm up" before I get good sound. Starts out silent, and then some scratchy sound, before it eventually sounds fine. I'm thinking its a tube problem? I did swap out the 5U4G and 6SN7 with spares I had handy, but no difference. Are the 6L6's the likely suspects? I haven't changed them yet.. I did test all tubes a couple weeks ago with my (admittedly not so great) Lafayette tester, and they checked "OK", but I'm not sure that is accurate. Any advice is much appreciated! Thanks, Carl.

Rather a difficult call--since you replaced all caps, and a "few resistors", it would lead me to assume that a tube or two was poor. I guess that I would try changing a whole NEW set of tubes, one at a time, to see if, where, there was any difference ?
Ron Rich

Thanks (again) Ron. I went through each tube with one or two spares that tested "good" on my tester, including the 6L6's. No difference; still takes several minutes to get good sound. I also tried replacing each tube with a "cold" one after the amp was up and running properly, and I can't isolate or reproduce the problem by replacing just one tube at a time with a cold one. I didn't try changing everything out at once yet. As long as you keep playing records, the sound is great. If amp is off for a few minutes, problem returns. Takes more than a full 78 played to warm up from cold start. I did have some general low volume before the recap, but not this time- delay issue. Cabinet volume control works fine once up. "Gain" and "Tone" controls seem to work properly. There is also a "P/NP" switch which I believe is for record quality(?). It does effect "loudness", but problem is (relatively) same in either position.

I did change the cartridge from a Shure crystal type with the spike, to a Pfanstiehl P-51-3 at the same time as the recap, so I'm not 100% sure what actually improved the sound. Is there something with the cartridge change that could be the issue? Any thoughts are appreciated ! Carl.

Carl,
Doubt it's the cartridge--would need to meter the power supply to go on from here-- Ron Rich

Maybe not enough voltage to heaters?

Who knows--that what a meter is for---post it, when you find it--Ron Rich