Whats a Good 6L6 circuit? - Page 2

Peter Menting · 24th April 2004, 05:52 PM

Sy; Yes it is, 6Sn7-6sn7-KT66 (Triode Rigged)-15WPC. (Pgs 220-221)

Regards
Pete

Sch3mat1c · 24th April 2004, 06:58 PM

Quote:

Originally posted by SY
Williamson.

Until you add NFB around a crappy OPT. Ask me about motorboating and 100kHz power oscillators, I dare you.

Tim

EC8010 · 24th April 2004, 07:04 PM

The output transformer as designed and specified by Williamson was superb. The questionable LF stability was mainly due to an oversight on Williamson's part (he couldn't be perfect everywhere). David Hafler fixed the LF problem by increasing the value of the coupling capacitors to the output valves.

andyjevans · 24th April 2004, 07:07 PM

If you look at the thread on Leak Stereo 20 there should be my circuit for EL84s. I also use this identical circuit for 6L6 in UL PP on a pair of Leak TL25 chassis, except I'm currently using a 500 ohm cathode resistor on each 6L6 which is loafing along, but I have a small room. It's a simple circuit with few parts and it sounds very nice. This will get you going with very little effort. SY's comments about safety are, as always, worth reading carefully.

SY · 24th April 2004, 07:22 PM

Andy, IIRC, the TL25 was a Williamson but with a pentode input?

What are you getting for power out of that?

andyjevans · 24th April 2004, 07:39 PM

Andy, IIRC, the TL25 was a Williamson but with a pentode input?
What are you getting for power out of that?>

Hi there SY - Well, this pair of monobloks started off as rusty chassis with no transformers so the TL25 is rather nominal, although they do look quite nice now. I used a 6.6KOPT from Danbury with the beefy core (ex-Maplin part) which is quite good. I have about 20v on the grids of the 6L6s and 500 ohms cathode resistor so about 40mA. Loafing along. Sounded nice so I didn't carry on changing values. My idea was to use a quad of 7519, which I have ready. I got sidetracked into testing out loads of 6J5s and 6C5s in the front end, which has been good fun. Nice tubes in the archives of the 6J5, and much cheaper than 1940s 6SN7s for sure - plus you get the round plates if you like. Just listening to some Brimar ST shape 6J5 round plates as we speak. Nice! That old '40s smooth silky sound. Before those I was groovin' to some RCA metal 6C5s - surprisingly nice too. I've gone single triode for the front end - these old tubes are just too much fun.

hacknet · 24th April 2004, 08:08 PM

Quote:

Originally posted by SY
The original Williamson circuit was published in Wireless World. Quite a few variations were published in Audio Engineering and Audio- several are available reprinted in the Audio Anthology series. I haven't seen Morgan Jones's book yet, but I'll bet it's in there, too.

oh. thats why. i don`t have one of those books lying aroun....

Peter Menting · 24th April 2004, 08:39 PM

Try this site;http://www.xs4all.nl/~.ideas/amps for info on the Williamson amp.

Regards
Pete

Peter Menting · 24th April 2004, 08:43 PM

Oops--my mistake; should be http://www.xs4all.nl/~ideas/amps ----Sorry!

Pete

hacknet · 24th April 2004, 09:12 PM

Yup. i did a wireless world search and got that too. Thanks!

i`ve found the original issue. Wireless World issue

24th April 2004, 07:04 PM	#13
EC8010 diyAudio Moderator Join Date: Jan 2003 Location: Near London. UK	The output transformer as designed and specified by Williamson was superb. The questionable LF stability was mainly due to an oversight on Williamson's part (he couldn't be perfect everywhere). David Hafler fixed the LF problem by increasing the value of the coupling capacitors to the output valves. __________________ The loudspeaker: The only commercial Hi-Fi item where a disproportionate part of the budget isn't spent on the box. And the one where it would make a difference...

24th April 2004, 07:22 PM	#15
SY diyAudio Moderator Join Date: Oct 2002 Location: Austin, TX Blog Entries: 1	Andy, IIRC, the TL25 was a Williamson but with a pentode input? What are you getting for power out of that? __________________ "...we stumble and get up, we are sad, confident, insecure, feel loneliness and joy and love. There is nothing more; but I want nothing more.” - Christopher Hitchens 1949-2011

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24th April 2004, 05:52 PM	#11
Peter Menting diyAudio Member Join Date: Jul 2003 Location: Blackstone VA	Sy; Yes it is, 6Sn7-6sn7-KT66 (Triode Rigged)-15WPC. (Pgs 220-221) Regards Pete

24th April 2004, 07:07 PM	#14
andyjevans diyAudio Member Join Date: Sep 2003 Location: London	If you look at the thread on Leak Stereo 20 there should be my circuit for EL84s. I also use this identical circuit for 6L6 in UL PP on a pair of Leak TL25 chassis, except I'm currently using a 500 ohm cathode resistor on each 6L6 which is loafing along, but I have a small room. It's a simple circuit with few parts and it sounds very nice. This will get you going with very little effort. SY's comments about safety are, as always, worth reading carefully.

24th April 2004, 07:39 PM	#16
andyjevans diyAudio Member Join Date: Sep 2003 Location: London	Andy, IIRC, the TL25 was a Williamson but with a pentode input? What are you getting for power out of that?> Hi there SY - Well, this pair of monobloks started off as rusty chassis with no transformers so the TL25 is rather nominal, although they do look quite nice now. I used a 6.6KOPT from Danbury with the beefy core (ex-Maplin part) which is quite good. I have about 20v on the grids of the 6L6s and 500 ohms cathode resistor so about 40mA. Loafing along. Sounded nice so I didn't carry on changing values. My idea was to use a quad of 7519, which I have ready. I got sidetracked into testing out loads of 6J5s and 6C5s in the front end, which has been good fun. Nice tubes in the archives of the 6J5, and much cheaper than 1940s 6SN7s for sure - plus you get the round plates if you like. Just listening to some Brimar ST shape 6J5 round plates as we speak. Nice! That old '40s smooth silky sound. Before those I was groovin' to some RCA metal 6C5s - surprisingly nice too. I've gone single triode for the front end - these old tubes are just too much fun.

24th April 2004, 08:39 PM	#18
Peter Menting diyAudio Member Join Date: Jul 2003 Location: Blackstone VA	Try this site;http://www.xs4all.nl/~.ideas/amps for info on the Williamson amp. Regards Pete

24th April 2004, 08:43 PM	#19
Peter Menting diyAudio Member Join Date: Jul 2003 Location: Blackstone VA	Oops--my mistake; should be http://www.xs4all.nl/~ideas/amps ----Sorry! Pete

24th April 2004, 09:12 PM	#20
hacknet diyAudio Member Join Date: Nov 2002 Location: sg	Yup. i did a wireless world search and got that too. Thanks! i`ve found the original issue. Wireless World issue

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