No, but it's been done more or less, with the related 6GH8A

Posted by Bambi B (A) on April 27, 2010 at 09:05:39

In Reply to: Anyone try 6BL8 as a driver in ST70? posted by bcguitar on April 26, 2010 at 14:09:34:

bcguitar,

As others have mentioned, the 6BL8 has a different pinout than the 7199. I think there is more than one replacement board for the ST70 that uses the 6GH8A.

The 6BL8 is part of a family of tubes that as far as I can tell are more or less interchangable:

6GH8, 6U8, 6BL8, 6EA8 ratings:

tube....pentode Trans.....power.....triode Trans....power

6GH8....8500 umhos......2.5W......7500 umhos....2.5W
6U8.......7500 umhos......2.5W......5000 umhos....3W
6BL8.....5000 umhos......1.5W.......6200 umhos...1.7W
6EA8.....6400 umhos..... 3.1W..... 8500 umhos... 2.5W

-As you can see the ratings vary a bit- the 6GH8A output is more enthusiastic than the 6BL8. I read that the 6GH8 was developed for television and to avoid NOS branded for TV. I use an Amperex 6GH8 as substitute for the 6U8 in a McIntosh MR67 tuner as recommended by designer Modaferri. I can not distinguish the Amperex 6GH8A from the 6BL8 (ECF80) in construction.

The MR67 uses the 6BL8 as the "pre-pre"-amplifier tubes and I think the sound is fantastic. There is a premium 6BL8 (Euro des. ECF80) called either E80CF or 7643. Theses are gold pin, military and low noise, and ruggedised. I bought 6 brands of E80CF including the glamourous Valvo red label, pinched waist, but found that there are really only two designs- the Philips/Amperex/Valvo/Mullard with the heavy triangular getter support and the German one Telefunken/Siemens which are made by Telefunken. Of the two, I much prefer the construction quality and sound of the Philips one.

I liked the sound of the 6BL8 enough that a couple of years ago I looked around for a headphone amp that used it.

If fussing with an ST-70, you might benefit from visiting the Dynaco Doctor forum of this site:

http://www.audioasylum.com/forums/dynaco/bbs.html

I have a PAS 3 and ST70 which I hope to someday revive, though I imagine they will be redone more or less as stock- I'm not knowledgeable enough to hot rod anything,..

Cheers,

Bambi B

This post is made possible by the generous support of people like you and our sponsors:

Follow Ups Full Thread

Topic - Anyone try 6BL8 as a driver in ST70? - bcguitar 14:09:34 04/26/10 (11)

No, but it's been done more or less, with the related 6GH8A - Bambi B 04/27/1009:05:39 04/27/10 (7)

RE: No, but it's been done more or less, with the related 6GH8A - Eli Duttman 19:16:29 04/27/10 (0)

RE: No, but it's been done more or less, with the related 6GH8A - becketma@yahoo.com 13:21:36 04/27/10 (5)

6BL8_ECF80_E80CF_7643 - Bambi B 15:28:21 04/27/10 (4)

RE: 6BL8_ECF80_E80CF_7643 - becketma@yahoo.com 22:39:18 04/28/10 (2)

Yes, I found only two European designs - Bambi B 06:59:15 04/29/10 (0)

RE: 6BL8_ECF80_E80CF_7643 - becketma@yahoo.com 22:42:41 04/28/10 (0)

Thanks for all the info and - bcguitar 19:19:22 04/27/10 (0)

RE: Anyone try 6BL8 as a driver in ST70? - Tom Bavis 05:51:27 04/27/10 (1)

Cool, thats what I thought. - bcguitar 08:32:09 04/27/10 (0)

RE: Anyone try 6BL8 as a driver in ST70? - Michael Samra 14:26:07 04/26/10 (0)

Follow Ups

No, but it's been done more or less, with the related 6GH8A - Bambi B 04/27/1009:05:39 04/27/10 (7)

RE: No, but it's been done more or less, with the related 6GH8A - Eli Duttman 19:16:29 04/27/10 (0)

RE: No, but it's been done more or less, with the related 6GH8A - becketma@yahoo.com 13:21:36 04/27/10 (5)

6BL8_ECF80_E80CF_7643 - Bambi B 15:28:21 04/27/10 (4)

RE: 6BL8_ECF80_E80CF_7643 - becketma@yahoo.com 22:39:18 04/28/10 (2)

Yes, I found only two European designs - Bambi B 06:59:15 04/29/10 (0)

RE: 6BL8_ECF80_E80CF_7643 - becketma@yahoo.com 22:42:41 04/28/10 (0)

Thanks for all the info and - bcguitar 19:19:22 04/27/10 (0)

No, but it's been done more or less, with the related 6GH8A

Post a Message!