Re: Suggest a tube for me for a preamp

Posted by Naz (A) on December 19, 2005 at 22:36:44

In Reply to: Suggest a tube for me for a preamp posted by Russ57 on December 19, 2005 at 11:27:38:

An easy path might be to try an ECC99 ... same pinout but much better specs than a 12AU7 and will yield better results. I'm not a fan of 6CG7 for driving but not too bad for voltage gain depending on type and yes, I'd agree they are a better alternative to 12AU7.

A better alternative would be to use one of my favourite non-NOS twin triodes for driving circuits, the 6H30P, and they are no slouches for voltage gain either. Excellent linearity, low rp, high gm and great sonics - full detailed and dynamic. But only as long as enough heater current is available - 800mA per tube. You could keep it simple and stick to the existing circuit with some minor changes or get adventurous.

Personally, I like tube Current Source circuits and this tube will work well if 1.3K OP impedance (or thereabouts) is sufficiently low for the application. However if you need a very low OP impedance try one of these in White CF config. On paper at least the specs are stella: very low distortion, extremely low (symmetrical) output impedance of only 6 or 7 ohms and very high PSSR, in the order of 50dB! I haven't tried one as a Pre output but I sure have (and do) use this circuit to drive a pair of 845s in parallel with a swing requirement of near 400V P-P, without any degradation in HF!

Oh, and you could easily keep the existing circuit's direct coupling between the stages!

Regards,
Naz

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Follow Ups Full Thread

Topic - Suggest a tube for me for a preamp - Russ57 11:27:38 12/19/05 (23)

Re: Suggest a tube for me for a preamp - Mike ST 16:18:21 12/22/05 (0)

Re: Suggest a tube for me for a preamp - Eli Duttman 03:05:43 12/21/05 (3)

What I am wondering - Russ57 04:12:24 12/21/05 (2)

Re: What I am wondering - Eli Duttman 02:51:06 12/22/05 (1)

Actually - Russ57 05:19:22 12/22/05 (0)

one step at a time - Joel Tunnah 05:36:38 12/20/05 (3)

...and maybe the 12FQ7, which (I think) requires NO changes? (NT) - jeffreybehr 10:47:34 12/20/05 (2)

Negative ... - Eli Duttman 02:45:28 12/21/05 (0)

I even have some of them in need of a home(nt) - Russ57 11:08:58 12/20/05 (0)

Re: Suggest a tube for me for a preamp - Naz 22:36:44 12/19/05 (0)

Re: Suggest a tube for me for a preamp - Jimmy 19:49:14 12/19/05 (0)

Re: Suggest a tube for me for a preamp - pedroskova 17:18:26 12/19/05 (5)

I was strongly considering that terrible tube - Russ57 10:51:27 12/20/05 (0)

Would you elaborate on why the 12B4A is terrible? (nt) - Vatron 06:52:59 12/20/05 (2)

It's getting terribly popular...and I'm terribly poor. ;^) NT - pedroskova 08:51:58 12/20/05 (1)

Don't worry it's still terribly cheap. - Scholl 03:32:58 12/21/05 (0)

Re: Suggest a tube for me for a preamp - Scholl 03:35:02 12/20/05 (0)

Re: Suggest a tube for me for a preamp - Scholl 16:25:48 12/19/05 (0)

A couple of ideas! - grhughes 13:31:53 12/19/05 (4)

Re: A couple of ideas! - fred76 16:12:48 12/19/05 (2)

Re: A couple of ideas! - grhughes 17:24:51 12/19/05 (1)

Re: A couple of ideas! - fred76 18:23:32 12/20/05 (0)

Re: A couple of ideas! - andy evans 14:08:00 12/19/05 (0)

Follow Ups

Re: Suggest a tube for me for a preamp - Naz 22:36:44 12/19/05 (0)

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