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Please Suggest: Old Tube Usages
Please Suggest: Old Tube Usages
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Old 16th August 2005, 10:27 AM   #1
CLS is offline CLS  Taiwan
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Join Date: Jun 2005
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Default Please Suggest: Old Tube Usages

Hi there,

I bought some NOS tubes several years ago, hopefully I can make some decent stuff out of them in the rest of my life. Here they are:

"Small" ones:
27 (Sylvania)
5687 (TungSol)
6J7 (Philips/RCA)
6SJ7 (RCA)
6EJ7 (Brimar)
6J5/G/GT (GE/Mullard/Ken Rad)
6S45PE/6C45Pi (Russian Military)
6H30pi (Russian Military)

"Middle" ones:
6EM7 (GE/Sylvania)
6V6/G/GT (Amperex/Unknown '40 British Military/GE JAN/RCA JAN)

"Bigger" ones:
811 (Sylvania JAN)
SV811-3 (Svetlena, this is not "NOS")
6080 (Philis/GE/Sylvania)
6336 (Cetron Graphite plates)

5Y3GT/5Y4GT (GE/Sylvania/RCA)
82 (RCA)
GZ37 (Mullard)

I've been thinking of several possibilities:

Line stages:
1) 27 with CCS load
2) 6J5 with CCS load
3) 5687 with choke load or OPT
4) 6S45PE or 6H30pi with OPT

Small amps:
1) 6H30pi single tube/single stage SE
2) 6S45 single stage SE
3) 6EM7 alone SE or PP
4) 6J7 (or 6J5) -> 6V6 SE or PP

Bigger amps:
1) 6J7 -> 6V6 -> (6080CF) -> 811 SE
2) 6EM7 -> SV811-3 SE
3) 6SJ7 (or 6EJ7) -> 6V6 -> 6080 or 6336 PSE or PP
4) 6EM7 -> 6V6 -> 6336 OTL

Other usage: 6080 and the likes as rectifier....

With the list, it seems the "small amp" group would be the most fun to build & use. And there'll probably be much trouble to deal with the "bigger amp" group. Maybe I'll need some more "middle" tubes for proper driver stage....

Your suggestions & experience sharing will be highly appreciated
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Old 16th August 2005, 07:03 PM   #2
PRR is offline PRR  United States
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Location: Maine USA
27 is, by later standards, a very low-performance device. However its low Gm stays very constant with current, at higher currents. Working alone as a line-amp, I'd think the output impedance is high.

6J5, and 6J7 triode-strap, are so linear that CCS seems pointless. Use them as if it was 1937 all over again.

As a quick/easy/good project, hard to beat one or two 6EM7. If you have lots of them, parallel your way to power.

You have enough big triodes to heat a house. I've never found much audio use for them: the gain is so low that driver design dominates the result.

All of these tubes are good for something. But all will need a lot of other stuff. Especially iron. Even the OTL needs a monster power transformer. These other parts have major impact on sound and cost. So I like to start with a vision of the whole amp, rather than with a tube.
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Old 17th August 2005, 03:36 AM   #3
CLS is offline CLS  Taiwan
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Join Date: Jun 2005
Location: Taiwan
Thanks a lot for the advices

Originally posted by PRR

These other parts have major impact on sound and cost. So I like to start with a vision of the whole amp, rather than with a tube.
Yes, yes Now I have a set of Lundahl irons good for a pair of mono blocks. The mains are 350V/630mA with some filament supplies & the OPTs are 3k:8R good for 100mA SE. There're also some power chokes & a pair of anode chokes.

So I guess they only fit with the 811 in class A2 SE (Shishido), or I could also try choke input power supply for 6EM7. I'll probably need 5k or higher impedance OPT for SV811-3 & 6V6. And another pair or two low impedance OPTs for those 6080 series (if I really build them)....

System-wise, actually I'd like to build a relatively powerful amp (10w at least) for the bass department to replace the current Altec 1568A. The mid-high portion is now served by 300B SE which I'm very satisfied with.

Small amps might be used to serve the high if I made it 3way active, or a second minimalist system.

I adore 6EM7 very much, too. I regret that I didn't buy more (I only got 6). It's now still inexpesive but harder to find good NOS. Instead, I have too many 6080s which seem hard to use I just thought I'd build some regulated power supplies

Looking back, I feel that I was too greedy at the time I bought them. All impulse, no plans And my thinking is always changing....
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