• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Cheap alternative to EF86

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Wavebourn said:
6EJ7 looks good on paper as well.

Most of them don't sound as good as you might expect, and can be quite microphonic - might just be the batch of Zenith and Scott (Sylvania??) branded ones I ran across.. (Some late Scott tube tuners used them in the IF strip, as did a lot of tube tv sets of the late 1960s.) IIRC There is a European equivalent which is the EF184..
 
I took a look at the 6BR7 and it looks excellent. The national valve museum has an interesting comment on the 6BS7, it reacons that it was a version of the 6BR7 specifically marketed at incompetent DIY'er, as any competent engineer should get just as good results from the 6BR7. The 6BS7 seemed to fall out of favour because of this marketing angle, so availability is likely to be poorer than for the 6BR7. Also who really want's to mess about with top caps unless absolutely essential.

At the moment the 6BR7 is the winner, but it depends on the availability with my preferred supplier.

Shoog
 
Shoog said:
I took a look at the 6BR7 and it looks excellent. The national valve museum has an interesting comment on the 6BS7, it reacons that it was a version of the 6BR7 specifically marketed at incompetent DIY'er, as any competent engineer should get just as good results from the 6BR7. The 6BS7 seemed to fall out of favour because of this marketing angle, so availability is likely to be poorer than for the 6BR7. Also who really want's to mess about with top caps unless absolutely essential.

At the moment the 6BR7 is the winner, but it depends on the availability with my preferred supplier.

Shoog

That's a funny comment really from the museum: it seems most unlikely that Brimar would produce a special version with amateurs in mind. The top cap is only the G1 connection so there are no voltage issues; Brimar presumably aimed at getting the grid wiring as far as possible away from the heater circuitry - a.c. heaters were of course the norm in those days.

6BR7 is stocked by a number of UK dealers, but whilst EF86 is currently manufactured, I doubt that anyone will start making 6BR7s.

Recently I have found six on ebay and they didn't cost me very much.

7N7
 
Alternative to EF86 would be the American made RCA 5879 sharp cut off pentode.
I've got one in place of the EF86 in my DIY Leak TL25+ clone..only difference is the pin designation and its been working flawlessly for quite a long time now. I think it sounds as good as the EF86 or better.
 
Shoog said:
I saw a lot of three go up on Ebay yesterday for �2.99, though they were untested. From Colomar they seem to go for about half the price of the EF86.[...]
Shoog

I bought them for £2.99; I bought three before from this bloke and they were fine; I wonder where he got them? One is marked "pre-production sample"!

7N7
 
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