Balanced microphone tube preamplifier

[mikets]

Balanced Tube mic pre!?
What about this one:
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Hmm Pat again [img]graemlins/.gif[/img]

Actually, after much research on the topic of mic tube pres, I decided to build the RCA BA2B, I believe this is the "API 312 of the Tue mic pres". Here is the schematic from Larry Seyer:
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I contacted the gentlemen and he was very kind to give me info on the circuit. I contacted as well mr Lundahl, and he told me they are making replica of the UTC LS-27 - namely LL1680.

A friend of mine told me , that the same basic circuit (RCA BA2B) is used in D.W.Fearn VT1 and VT2 which I've heard and I like very very much.


If you you need more gain, you could think of
RCA BA-21A
or maybe better - just adding additional SRPP stage like in the Pulteq DIY EQ, or G9 or:
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Ladyes and gentleman Mr.Pat one more time [img]tongue.gif[/img]

Cheers

[cjenrick]

Zero headroom in that 5687 circuit !

[Shalimar]

WHAT? Have you even tried an 5687 in a SRPP setup? I've done perhaps ten dif versions.. plenty of headroom. That's a common way of driving 300Bs. A lot more demanding than interfacing with a linelevel input. Have worked for a lot designs in the last 30-40 years.

I know you don't like Pat and he may be the greatest wanker on Earth. But that's not a Pat design. That's a textbook 5687 SRPP design. Let's not give him credit for that, 'kay?!

The other schematic is not a Pat either. In fact I don't think he could design anything, despite having a gazillion schematics.

His kits are flaky, expensive and not as advertised, so the grapewine goes.

But I've bought a lot of schems, cheap, always on time. Never a single hickup.

So, unless he banged your sister or something, cjenrick, then chill.

[Shalimar]

Hmm, didn't mean to come off like that. But if he did bang my sis, I'd have him discharge those four 15.000yF/250V caps in my pre with his tongue..

[axis.dk]

A friend of mine told me , that the same basic circuit (RCA BA2B) is used in D.W.Fearn VT1 and VT2 which I've heard and I like very very much.

Hmmm..While I have never looked inside one of them Fearnīs...I donīt think itīs the same circuit..!!!, but I could be wrong..just a feeling..

Kind regards

Peter

[IJR]

I like CCa in SRPP, or ecc88.
Try it!