I found a pair of 345 Cunningham engraved base balloon output tubes in one of my old consoles.

I tested both today and one came in at 92% (with 60% being minimum good on my Precision 10-60 tester)
and the other tube tested at 105%.

Are these close enough to be a balanced PP pair or would the gap be considered too much ?
I am sure they will sound fine to me but I plan to put these up for the audio-philes to bid on
and want to make sure I describe them properly as I am not usually a tube seller.

Thanks as always
Bruce

All you can do is post your results. The tube tester you have is only an emissions type and won't carry a lot of weight with the 'philes. If you were to test them on a TV7 it would mean more but one is probably going to be better than the other, same as your tester. They both seem to be very good so that should help.

I only hope that 105% reading doesn't indicate that the tube is slightly gassy. Elevated tester readings often indicate that...

Can you try them in another tester and get a "second opinion?"

Larry

Good idea to try them in a 2nd tester.

I have 3 around (a triplett and a BK too) here so will try all of them plus run them as a pair
in a Scott AW15-the 45 is a sub for the 2A3's in the Scott.
I don't want to wreak my 100% feedback with a faulty test.

Your readings are close enough to call this set compatable. In another 100 hours of use, readings may change. Depending on the application, bias adjustments may be made to yield the least hum and best overall performance, but in the real world 10% variance is meaningless unless the tubes are already red linded. Probably not an issue for anything designed (in the past) to use 45 tubes, which werre used until they burned out with no other ill effects.

Hope this is helpful.

I would not list them as a matched pair, you don't have the equipment to make that call. Just show pics of each tube in the tester and let the buyer decide. I would never offer a guarantee of any kind on Ebay for tubes, too easy for the buyer to mess them up in bad equipment or just plain try to rob you.

My $.02. To me matched tubes is working as a push pull pair within a couple of milliamps in my amps. Testing is nice but that's only a starting point.

Doug

Bruce

Best to list your test results. Tubes could be matched under specific conditions but not others. I don't believe most tubes shown as matched are that way under different operating conditions. It almost takes tubes made at the same time and manufacturer to be matched. At least your tubes are both Cunningham. Stress that they are both CX345.

They'll probably wind up in two single-ended amps anyway, where appearance is more important.

+1

L

I just put the 2 345's into one of my Scott AW15's. Normally the Scott uses 2-2A3's but a 45 is a good sub per my tube book.
The tubes sound wonderful and have huge volume.

They even fit side by side with clearance between. Gonna dig out my B & K tester next and see how they do there.

Better not play with them too much. You might decide to keep them...

Larry

Emmissions can be measured and recorded after initial bake in at the factory. There is a good chance that similar tubes will age gracefully together, but there is no guarantee. Unless things get out of whack completley in use, it takes instruments far sooner than ears to notice a problem. Small cathode resistors and parallel meters can measure current flow through the tube and will indicate looming problems before they become fireworks.

Turns out my B & K 550 did not have a socket for 4 pin tubes.

BUT My trusty Triplet tester did and both tubes tested strong at similar percent ratings as the 1st tester.
I decided I am going to offer them here 1st in the classified's before it's off to that auction center.

Thank you all for the tips and advice. I have not really been a tube guy but am learning.

BwS

Bruce

Although 345's worked well as replacement for 2A3's you should measure plate voltage. A 45 draws half current as a 2A3 so this may allow plate voltage to be too high. A smaller load on the power supply will cause voltage to be high.

Many thanks for choosing the classifieds here. Someone will probably beat me to them, but thanks all the same!

Larry