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What is this Amp?


thebes

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On ‎4‎/‎19‎/‎2017 at 5:23 PM, mike stehr said:

I may have a local find this Saturday...the Mechanic at work had a cousin or brother pass away a few months back. He was a radio or audio dude.

 

It was the Mechanic's brother. He was a thirty year television service tech...Television, VCRs, video cameras, RTRs, etc...

The mechanic and his other brother are spearheading the whole thing. They want to sell all the deceased brother's bench/test gear as a lot, and that's over my head.

They only had a few loose tubes in a few boxes. The rest are boxed, and he'll have them up next weekend...er, okay...

 

There is a ton of stuff, but sort of light on audio stuff.

 

So I rooted through the loose tubes, and spied a ST tube with a familiar H plate structure. Ah, a GE 2A3.

I bought a NOS GE ST 2A3 locally years ago for 25 bucks. I've always kind of been looking for a mate over the years, and now the prices for a GE H (or is it S?) plate 2A3 are getting up there.

 

Now these old triodes can be sketchy, but we both agreed the guy wouldn't throw a dead tube with other loose tubes that look new. So I bought the 2A3, some 6SN7, a 6F6, a couple 6V6, and 12AV5...and a Simpson 260.

The tubes were 2 bucks each, so the 2A3 was 2 bucks.

 

I spent 20 bucks...driving home thinking if that 2A3 tests strong, I have a pair of GE 2A3 tubes for my 2A3 stereo SET amp.

But I was really doubtful.

The triode shaman were on my side today. The 2A3 tests as strong or stronger with regard to emission than the NOS one I have!

 

I'll be returning next week...

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Dave,

The guy was a television tech, so I'm thinking that the majority of the boxed tubes are going to be either NOS television tubes, or pulls. There may be some radio tubes like the loose 2A3 I bought, like maybe a 45, but who knows?

 

The guy spearheading the thing more than likely thinks the boxed tubes will be NOS, and I have no idea what he wants for each tube, or if it's for the whole lot or what. Not to mention testing...

This guy is a cantankerous old dog...his brother Mike the Mechanic was helping him out just to be nice, until he was accused of stealing money...really? Your own brother?

Asked Mike if he'll be there this weekend. NOPE!!

The sale was extremely disorganized, some stuff was pilfered, like some ribbon microphones...it was ugly.

 

Mike mentioned to go there late Sunday afternoon when the guy is desperate. I dunno, I could show up a half hour early Saturday and see...

 

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9 hours ago, mike stehr said:

Listened to the SET amplifier tonight with the GE 2A3 tubes. These give the amp a slightly more organic/natural sonic presentation than the Sylvania 5930/2A3W. Yummy...

Mike, if you have time one day, can you measure the plate voltages, current, and bias with the GEs and Sylvanias (at the exact same line voltage)?  If radically different, it would be interesting to graph the load lines to compare the 2nd harmonic distortion characteristics which might explain some of the difference in sound that you noted.

 

Maynard

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10 hours ago, tube fanatic said:

Mike, if you have time one day, can you measure the plate voltages, current, and bias with the GEs and Sylvanias (at the exact same line voltage)?  If radically different, it would be interesting to graph the load lines to compare the 2nd harmonic distortion characteristics which might explain some of the difference in sound that you noted.

 

Maynard

 

I could do that...I probably should anyway, at least to determine bias with the GEs.

It would probably be safe to assume different brands of 2A3 would load in circuit with variations in plate voltage, current, and bias. Of course assuming all these 2A3s have the same emission/transconductance measurements.

 

I'm sure you're correct that I'm hearing different distortion characteristics (2nd) with different brands or types of 2A3.

 

 

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2 hours ago, sheltie dave said:

Did he have that frown on his face, Mike? 

 

No tubes for you, leave!

 

His Brother the Mechanic said he didn't even have a sale last weekend!

I should have asked the Mechanic if the guy still wants to sell the tubes or not, but he has tomorrow off. So Monday I suppose...maybe I can get a phone number and talk to the old dog...

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