Re: SE with EL 84?

Posted by jdarg on February 26, 2001 at 11:59:53

In Reply to: SE with EL 84? posted by Vince on February 23, 2001 at 09:45:14:

I had toyed around with very simple SE EL84 a year or two ago while I was in the midst of finishing other projects (one of which was a Citation V, what a coincidence!)

I was using cheapskate Hammond 125E's and biasing the EL84s (in triode mode) around 40-45ma each. Chassis was a stripped Heathkit EA-2 I scored for $1, but thats another story.

I used the 6CG7 as simple plate loaded driver because I had a stash from my Citation V (this continues to be one of my favortites for driver duties and I still use them ala Williamson in my rebuilt EA-3s, which are also EL84 PP ultalinear.

I tried 47K and 100K on the 6CG7 plates, and the 100K sounded much better to me for some reason, biased around 4v. Cathodes of the driver stage were bypassed with Cerafines. Revisiting a similar (Williamson front end) VA stage later I liked 47K more in that application, maybe the difference was resistor brands or something like that.

No NFB initially. Added a 1M pot to adjust global feedback, ended up pulling the pot because it never got turned lower than 1M. EZ81 rectifier and lots of capacitance in the second bank - only two banks, 40uf after the rectifier and almost 200uf in the reservoir. Driver and output b+ from the same tap PS. Couldn't do high volume, but was just the ticket for late night listening when you don't want strong bass disturbing the neighbors.

Wonderful sound. When I finished the 2A3, I tore down the EL84 SE (built on Heathkit EA-2 chassis) and maybe regret it, as a month later the 2A3 was torn down again because I decided it wasn't as good as the EL84 SE was, and is still in parts waiting for a new chassis.

Man, you should have heard that SE el84 sound! Maybe a bit tilted towards HF, but it was not a nasty, abrasive sound. Removing the bypass on the driver cathode would warm it up quite a bit, but I preferred it left in. Midrange wasn't great, bass was a even worse yet, but *very* tight since it didn't go much lower than 60hz.

Tried my One Electron UBT-3 output tranny's on the EL84 SE - they were the last pieces I bought to complete a 2A3 project. It had *much* better bass than the 125E, but the lack of power became more apparent. The 125E is no slouch and I lived with that setup exclusively for about three months.

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Follow Ups Full Thread

Topic - SE with EL 84? - Vince 09:45:14 02/23/01 (37)

Re: SE with EL 84? - steve shiels 06:25:02 03/3/01 (0)

Re: SE with EL 84? - jdarg 02/26/0111:59:53 02/26/01 (1)

Re: SE with EL 84? - Vince 18:23:29 02/26/01 (0)

Re: SE with EL 84? - Paul Joppa 00:52:43 02/25/01 (0)

Audionote OTO SE - Pland 16:51:53 02/23/01 (0)

you could try this as a second project - Chris 16:20:17 02/23/01 (1)

Re: you could try this as a second project - Kurt Strain 18:41:39 02/23/01 (0)

Vince, stop screwing around and simply turn this.... - mobile homeless 16:11:59 02/23/01 (16)

Re: Vince, stop screwing around and simply turn this.... - Kurt Strain 18:39:59 02/23/01 (0)

Re: Vince, stop screwing around and simply turn this.... - Vince 16:29:21 02/23/01 (14)

HF81 - Gary Kaufman 18:59:09 02/23/01 (13)

Re: EICO HF- 81 Ugly? I dont think so! - mobile homeless 00:53:29 02/24/01 (4)

Very beautiful indeed - Francis S 10:53:45 02/24/01 (2)

EICO HF-81 Questions and Tips for SET Curious - mobile homeless 09:40:47 02/26/01 (1)

Thanks for a very informative post. Great site too. - Francis S 21:26:43 02/26/01 (0)

Re: EICO HF- 81 Ugly? I dont think so! - Vince 07:23:22 02/24/01 (0)

Re: HF81 - Les Lammers 19:34:20 02/23/01 (6)

Once upon a time never comes again. - Yogi 11:19:09 02/24/01 (5)

Re: Once upon a time never comes again. - Gary Kaufman 11:50:25 02/24/01 (4)

What About the Fisher X-202-B - Tom S 22:45:51 02/24/01 (0)

Re: Once upon a time never comes again. - Jonathan Kranz 17:14:04 02/24/01 (2)

Re: Once upon a time never comes again. - Gary Kaufman 17:42:50 02/24/01 (1)

give or take a kilobuck.. - Yogi 22:44:40 02/24/01 (0)

Gollllllleeeeee! - Vince 14:39:21 02/23/01 (0)

Nah, try some more interesting stuff.... - Gary Kaufman 14:37:07 02/23/01 (5)

Re: Nah, try some more interesting stuff.... - Vince 14:43:27 02/23/01 (4)

Re: Nah, try some more interesting stuff.... - morinix 16:11:10 02/23/01 (3)

Re: Nah, try some more interesting stuff.... - Vince 16:18:53 02/23/01 (2)

Re: Nah, try some more interesting stuff.... - Gary Kaufman 19:05:14 02/23/01 (0)

sounds good to me (nt) - morinix 17:19:46 02/23/01 (0)

Wavelength Junior ... - JeffR 14:13:54 02/23/01 (0)

Re: SE with EL 84? - Hank Murrow 12:40:01 02/23/01 (0)

SE with EL 84? Indeed...A few to litter the landscape - mobile homeless 11:06:36 02/23/01 (0)

Re: SE with EL 84? - Paul Barker 10:56:38 02/23/01 (0)

http://www.decware.com (nt) - Rich C 10:42:26 02/23/01 (2)

Re:decware zen - hifitom 21:49:54 02/23/01 (0)

Here's some DIY - Chris 14:25:39 02/23/01 (0)

Follow Ups

Re: SE with EL 84? - jdarg 02/26/0111:59:53 02/26/01 (1)

Re: SE with EL 84? - Vince 18:23:29 02/26/01 (0)

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