RE: 26 DHT preamp

Posted by andy evans (A) on March 14, 2012 at 15:27:38

In Reply to: RE: 26 DHT preamp posted by andy evans on March 14, 2012 at 14:38:35:

Just a few comments on the 26 preamp - the Hammonds 156Cs are a tried and tested plate choke option - not the ultimate but very good. However, they are prone to hum and must be kept away from any magnetic fields - in particular the filament supply chokes which should be as much as a metre away in a separate box. I use 3 boxes - filament supply, PSU and preamp. The cathode resistors are wirewound surplus Dale - quality is critical. Must be 50 watts - they get hot. I use 10 watters in a series/parallel arrangement and mount them on the top of the chassis. 26s can sound a little better in starved filament, but this alters all the voltages with filament bias. I have also used glow tubes, and others use Salas shunt regulators - it's all in the DIY thread. There are lots of other details and circuit options - many use Lundahl LL1660/5mA in 4.5:1 stepdown for instance. If you build a 26 preamp I do urge reading the thread.

andy

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Follow Ups Full Thread

Topic - Line Stage Preamps for Fi 2A3 monos? - Frihed89 15:51:45 01/27/12 (23)

26 DHT preamp - andy evans 01:30:22 03/14/12 (4)

RE: 26 DHT preamp - Palustris 10:48:03 03/14/12 (3)

RE: 26 DHT preamp - andy evans 14:38:35 03/14/12 (2)

RE: 26 DHT preamp - andy evans 15:27:38 03/14/12 (1)

RE: 26 DHT preamp - Palustris 14:38:28 03/15/12 (0)

RE: Line Stage Preamps for Fi 2A3 monos? - skypop 09:46:15 02/08/12 (0)

in your indicated price range... - triode 10:58:58 01/31/12 (0)

RE: Line Stage Preamps for Fi 2A3 monos? - Manuel 11:11:35 01/29/12 (1)

Thanks. Nt - Frihed89 12:59:52 01/29/12 (0)

RE: Line Stage Preamps for Fi 2A3 monos? - benE 17:50:26 01/28/12 (7)

I've wondered about that - Frihed89 05:43:08 01/29/12 (3)

RE: I've wondered about that - benE 13:37:59 01/29/12 (2)

RE: I've wondered about that - HiFiOd 08:06:58 02/06/12 (1)

RE: I've wondered about that - benE 19:30:45 02/18/12 (0)

RE: Line Stage Preamps for Fi 2A3 monos? - charles1dad 04:17:51 01/29/12 (2)

Looks interesting - Frihed89 05:40:50 01/29/12 (1)

RE: Looks interesting - charles1dad 15:33:43 01/29/12 (0)

RE: Line Stage Preamps for Fi 2A3 monos? - Cpwill 05:57:18 01/28/12 (5)

The Sira has more tubes than a boiler! - Frihed89 10:40:27 01/28/12 (4)

RE: The Sira has more tubes than a boiler! - Cpwill 12:56:11 01/28/12 (3)

RE: The Sira has more tubes than a boiler! - PakProtector 16:48:30 01/28/12 (2)

RE: The Sira has more tubes than a boiler! - Larry I 10:36:11 01/30/12 (1)

RE: The Sira has more tubes than a boiler! - PakProtector 03:44:05 02/13/12 (0)

Follow Ups

RE: 26 DHT preamp - andy evans 15:27:38 03/14/12 (1)

RE: 26 DHT preamp - Palustris 14:38:28 03/15/12 (0)

RE: 26 DHT preamp

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