RE: PAS3 circuit issues

Posted by Thermionic27609 (A) on August 4, 2014 at 18:59:38

In Reply to: PAS3 circuit issues posted by Ralph on August 4, 2014 at 14:05:45:

To recap: I completely rebuilt my PAS-3X years ago from stem to stern with audiophile-approved parts, including the filament supply, volume pot (Alps Black Beauty), tube sockets, all resistors (Holcos before they stopped making them), and all film and electrolytic capacitors. It has increased B+ supply capacitance using Elna Cerafines following suggestions I got >10 years ago from Gordon Rankin. Bass controls are out of the circuit, and treble controls are out of circuit at center. The filament supply did not escape notice.

I appreciate your recommendations, but it's quite a long way from "your line stage is not working up to snuff" to designing a new line stage. At the point where you're using half a 12AU7 gain stage direct-coupled to a 12AU7 cathode follower, isn't that a tacit admission that one might as well go ahead a build a different preamp? It's not really a PAS-3X anymore.

I was under the impression that the PAS power transformer didn't really have enough current capacity to run 12AU7s optimally. At least I think that that was one of the conclusions of Norman Koren's analysis of the amp.

Considering the reviews I've read of various versions of the Aikido preamp, I've been thinking that I might build one if I decided I wanted an active line stage. I even went so far as to buy an enclosure intended for a new preamp, but that was before the economic crash eliminated my job, sent me scrambling to keep my head above water, and forced me to turn my hobby into a livelihood. At this point, I'm a professional Hammond/Leslie and guitar amp tech. I have a shop, and I repair and rebuild amps every day. I've neglected my own HiFi system for a few years since I've been too busy fixing everyone else's stuff.

If I built a volume control into my ST70 so that there were no cables between the pot/attenuator and the input stage of the amp, would that make it any more acceptable? There is room. My ST70 has a custom base that's deeper to allow for PP power supply caps.

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Follow Ups Full Thread

Topic - I think I'm over active line stages - Thermionic27609 21:36:12 08/02/14 (29)

RE: I think I'm over active line stages - sony6060 17:37:38 08/08/14 (0)

RE: I think I'm over active line stages - raq 07:24:49 08/07/14 (0)

Stick with it, there's a reason for everything ... - Naz 06:11:57 08/04/14 (0)

Your PAS3X - Lew 13:15:29 08/03/14 (2)

RE: PAS3X - unclestu 19:02:22 08/03/14 (1)

Add capacitance - 1973shovel 07:50:08 08/04/14 (0)

RE: I think I'm over active line stages - Eli Duttman 12:16:19 08/03/14 (0)

All depends on your sources. - gusser 10:50:12 08/03/14 (1)

RE: All depends on your sources. - Tre' 12:07:14 08/03/14 (0)

Measurements - Triode_Kingdom 09:25:13 08/03/14 (11)

RE: Measurements - Thermionic27609 15:06:52 08/03/14 (10)

RE: Measurements - Triode_Kingdom 20:12:34 08/03/14 (9)

RE: Measurements - Thermionic27609 21:36:37 08/03/14 (8)

RE: Measurements - Thermionic27609 07:35:58 08/04/14 (7)

PAS3 circuit issues - Ralph 14:05:45 08/04/14 (6)

RE: PAS3 circuit issues - Thermionic27609 18:59:38 08/04/14 (5)

Neglect - Triode_Kingdom 12:22:04 08/05/14 (1)

RE: Neglect - Thermionic27609 15:12:11 08/05/14 (0)

RE: PAS3 circuit issues - Ralph 08:13:34 08/05/14 (2)

RE: PAS3 circuit issues - Thermionic27609 08:56:31 08/05/14 (1)

It was a good basic preamp in its day - Ralph 10:03:20 08/05/14 (0)

The Hornshoppe's "The Truth" Might be a good solution.. - HotStamper 07:46:43 08/03/14 (0)

RE: I think I'm over active line stages - Stuben 07:19:31 08/03/14 (0)

Isn't all that simple. - twystd 01:58:17 08/03/14 (1)

RE: Isn't all that simple. - Thermionic27609 09:17:14 08/03/14 (0)

RE: I think I'm over active line stages - Alex M 01:50:09 08/03/14 (2)

Allen Wright - Triode_Kingdom 09:28:05 08/03/14 (1)

RE: Allen Wright - Naz 05:22:35 08/04/14 (0)

RE: I think I'm over active line stages - hennfarm 00:00:16 08/03/14 (0)

Follow Ups

RE: PAS3 circuit issues - Thermionic27609 18:59:38 08/04/14 (5)

Neglect - Triode_Kingdom 12:22:04 08/05/14 (1)

RE: Neglect - Thermionic27609 15:12:11 08/05/14 (0)

RE: PAS3 circuit issues - Ralph 08:13:34 08/05/14 (2)

RE: PAS3 circuit issues - Thermionic27609 08:56:31 08/05/14 (1)

It was a good basic preamp in its day - Ralph 10:03:20 08/05/14 (0)

RE: PAS3 circuit issues

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