Myles;

Whelp I got these tubes. Not sure how I know if one is better then another tho.

2-RCA 3-Mica Black plate 5751/ECC83

2-Matched RCA 5751 tubes (lo mu 12AX7 ECC83)

2- Matched Pair premium plate 12AX7

2 NOS Mullard 12AT7WA CV4024(12AT7 ECC81)

Most gave some readings for the tubes but not sure what that means. I think the numbers mean the plate voltage but some of the numbers are large and some are small..Must be in millampearage or millvoltages and some must give the whole number..

Kinda confusing..I'm assuming the higher the numbers the better the tube?

Also, depending on the amp, I'm assuming I want to check the tubes and see if they are within the operating range for each particular amp..

Can you clarify the meaning of the numbers they provide using there test equipment?

thanks

OK..here ya go Myles-

I guess I need to read a primer on tube testing..

2-Marched Premium 12ax7:
Fully tested on a calibrated TV-7 conductance tester at 43/47 and 47/49 where 32 is good. Originally sold and labeled for the Sanborn Company.
=======================
2-Matched RCA 5751 tubes (lo mu 12AX7 ECC83):
black ridge plates, 2 mica spacers, extra support rods between mica spacers and halo ring getters at the tops.

Tubes appear identical in construction!

Hickok TV-7B checked @ 42/41 39/44
====================================================
2-RCA 3-Mica Black plate 5751/ECC83

Test at 118/130, 120/130, on a EICO 667 Ttube tester.min:60
====================================================

2 NOS Mullard 12AT7WA CV4024(12AT7 ECC81):

These are the low noise CV4024 m8162 British Military version of the 12AT7, manufactured by Mullard in Mitchum, Great Britain, not the inferior Mullard re-issue tubes currently available!
Coded '654 R4D3' (Mullard Mitchum, 1984)
Pairs selected by factoring in both IP and Gm.
Gm tested at 3600/4500, 3900/4900. Min 2500, average new 3850 mho.
IP (plate current) 3.8/6.6, 4.1/6.4. Average new 3.7 ma.
Fully Tested on a Hickok 539C tester and guaranteed.

Well what does "low mu" mean?

Also, two test in the 40's while the 3-mica one gives test results in the 100's. Why the diff?

And thanks for your kind attention and advice..Your the man!!

I happened upon an old home entertainment center.... One even older than my memory, although we had something similar. This one was a TV, record player and radio in a cabinet on 6"-8" legs. (Unlike those of the 1970's where the entire cabinet reached the ground.)

Anywho... the back was open and I noticed tubes... a bunch of them. Pulled some from the TV and others from the radio, including single 5Y3 and 12AX7-GT tubes from the radio.

Some of the tubes (in particular, the largest TV tube) are obviously blown. Others look near pristine. Any chance they're worth anything to anyone. (Frankly, I don't own a tube amp so I can't even begin to entertain using them myself. 8^o )

Just thought I'd ask... I considered taking them to a shop to be tested but thought to ask your opinion before wasting time with them. (I have a list of mnfrs and models if you want to know the others. There are about 15 tubes in all, from Zenith, RCA, Raytheon, G.E. & Silvertone. (Which, in fact, was the brand name on the unit. Yes, I'm aware that was simply the Sears store-brand product name.)

Thanks in advance for any info you can provide...

Unfortunately I was in no position to take the entire unit. It was out in the rain waiting for the garbage man when I discovered it and there was EXTENSIVE damage to the electronics from the looks of it. By the time I came back with tools to extract the amp it had, alas, been removed to the dump.

Thanks for the info.

I've been thinking about having a guitar of mine refinished and was wondering if you could give me any references to choose from. I'm here in SoCal, but am open to shipping if need be. It's a '64 Strat, original owner, that was painted by some dumb ass kid, (me), because Eric Clapton had that psychedlic SG and I did the same to mine. It was refinished once, non-pro, but thought about doing it right. I've been told a refinished guitar will bring about half the market value, as I was thinking about selling it. It was originally sunburst.

Thanks
Scott

Thank you Sir

Scott,

Call Norm's Rare Guitars in Tarzana and ask for Jeff Lund and talk to him.

Talked to Jeff Lund, great guy, and he said that Pro re-finish would be the way to go. RS Guitarworks was his recommendation and being outside of Cal, they can use the right lacquer

Thanks again
Scott

Thanks again

Myles,

I purchaced a fine Radio Shack DVM and checked my B+ voltage and it came up Short; 371v for V1 and 323 for V2 and V3. The Power tubes and rectifier were at 390. My schematic says 420 is what I should be getting.

I diconnected V1, my Tweed mod from the voltage see if it was grounding out some of the voltage but nothing changed.

If you have any Ideas, aside from buy a knew amp let me know.

Thanks, Brendan

Hey Myles,

That trouble shooting realy worked out. I finally got the channel working properly.

The mod I installed was from Aspen Pittman's Tube Amp Book and the directions and diagrams are completly wrong.

I learned alot in the process though, Thanks for your help.

Do you Know where I get get the specs on my Electro Harmonics 5U4GB rectifier ? I want to find out if it can handle 100uf filter caps run in series.

Thanks again, Brendan

Myles,

I have a GT Soulo 45 with a problem that has gotten worse. The amp is breaking up a lot on gigs with difficulty in getting a clean sound at bluesrock level volumes. Last night was the worse it's been.

The rock edged stuff with some OD pedals sounded fine but the jazzier stuff had way too much breakup.

The last time it was similar but not as bad, I changed the power tubes and rebiased. (JJ6l6's).
It was better but still seems like this amp should have plenty of clean headroom even when the volume is up.
Could something be going on with the FX loop? Or one of the preamp tubes? I recently changed out the loop recovery tube because it was microphonic but new tube appears to be fine.

I have a solid state combo amp (with a speaker out) and I have a head. I know that with an A/B switch I can go from amp to amp from just one guitar. Can I go then to just one common head (speaker)? Do I also need a switch at that junction?
Thank you, your posts are great.

Your help with the two amps into one speaker was spot on. I found the switchers and now I feel dumb. Thanks for your help you are the man. Can I get that single 12" speaker in my combo work for this as well? (portability)