Sherwood S8000 transformers

mr2racer · 01:38 AM

Hello All,

Just bought a pair of Sherwood S8000 OPTs. I know they were meant for 7868 tubes in a PP configuration. Also that 7591's could be substituted. My question is this, since I only have the transformers at this point I'm free to build any circuit that uses compatible tubes, 7868,7591, 6l6... so any ideas what would be the best sounding amp to copy?

And does anyone know where I could get an electronic copy of the Sherwood schematic?

Kevin

Eli Duttman · 11th October 2010, 01:39 AM

If you really trust the "iron", consider emulating the Harman/Kardon Citation V. The Cit. 5 is Stu Hegeman's take on the venerable Mullard style of circuitry.

mr2racer · 11th October 2010, 02:27 AM

Eli,

Is there any reason not to "trust" the iron? The transformers don't look scorched at all. And they were taken from a working amp. At least that's what I'm told. If they ohm out OK can I expect them to work? Is there a better way to test them?

I'll look into the HK. I had an A-401 when I was in high school. I sold it to a friend in 1980. And I've been trying to buy it back since. Its hard for me to let things go.

Kevin

Eli Duttman · 11th October 2010, 02:53 AM

Hegeman's designs call for top notch magnetics. Sherwood did not use junk. However, the $64 question about bandwidth and magnetic headroom remains.

Look at the Cit. 5's picture. The "iron" is VERY substantial.

mr2racer · 11th October 2010, 03:13 AM

Eli,

I see what you mean. The transformers in that picture are roughly twice the size of the Sherwood's. What about a copy of the Sherwood amp? Or, I believe Fisher used the 7868 and the 7591 tubes also. Are there any other circuits you could recommend?

Kevin

dave_gerecke · 11th October 2010, 03:22 AM

Hello Kevin, I was just doing a quick scan through a couple of my schematics, I don't have the S8000, but I do have one of the S5000, which also appears to have used the 7868. I can email the S5000 schematic if you want it. Just drop me a PM with your email address and I will send it to you.

Peace,

Dave Gerecke

ronaldw441 · 11th October 2010, 04:39 AM

How about the output section of the Eico ST-70. Do a google search for the schematic.

Eli Duttman · 12th October 2010, 01:43 AM

Kevin,

There is a lot to be said in favor of the 7591 family. Of particular note is the fact that 7591s are as easy to drive as EL84s and 6V6s. Scott and Fisher took full advantage of that fact. They used the same small signal circuitry with both EL84s and 7591s.

wrenchone · 12th October 2010, 01:58 AM

7591As have two sources for new parts - Electro-Harmonix and JJ. The NOS parts are getting pretty pricey. EH makes a new 7868, but the pins are larger than the standard Novar socket. I'm pretty happy with the EH 7591As in my "Kingfisher" amp. Come see it at BA.

mr2racer · 15th October 2010, 12:41 AM

BA?

11th October 2010, 01:33 AM	#1
mr2racer diyAudio Member Join Date: Jul 2009	Sherwood S8000 transformers Hello All, Just bought a pair of Sherwood S8000 OPTs. I know they were meant for 7868 tubes in a PP configuration. Also that 7591's could be substituted. My question is this, since I only have the transformers at this point I'm free to build any circuit that uses compatible tubes, 7868,7591, 6l6... so any ideas what would be the best sounding amp to copy? And does anyone know where I could get an electronic copy of the Sherwood schematic? Kevin Last edited by mr2racer; 11th October 2010 at 01:38 AM. Reason: missed word

11th October 2010, 01:39 AM	#2
Eli Duttman diyAudio Member Join Date: Apr 2004 Location: Plainsboro, NJ	If you really trust the "iron", consider emulating the Harman/Kardon Citation V. The Cit. 5 is Stu Hegeman's take on the venerable Mullard style of circuitry. __________________ Eli D.

11th October 2010, 02:53 AM	#4
Eli Duttman diyAudio Member Join Date: Apr 2004 Location: Plainsboro, NJ	Hegeman's designs call for top notch magnetics. Sherwood did not use junk. However, the $64 question about bandwidth and magnetic headroom remains. Look at the Cit. 5's picture. The "iron" is VERY substantial. __________________ Eli D.

12th October 2010, 01:43 AM	#8
Eli Duttman diyAudio Member Join Date: Apr 2004 Location: Plainsboro, NJ	Kevin, There is a lot to be said in favor of the 7591 family. Of particular note is the fact that 7591s are as easy to drive as EL84s and 6V6s. Scott and Fisher took full advantage of that fact. They used the same small signal circuitry with both EL84s and 7591s. __________________ Eli D.

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11th October 2010, 02:27 AM	#3
mr2racer diyAudio Member Join Date: Jul 2009	Eli, Is there any reason not to "trust" the iron? The transformers don't look scorched at all. And they were taken from a working amp. At least that's what I'm told. If they ohm out OK can I expect them to work? Is there a better way to test them? I'll look into the HK. I had an A-401 when I was in high school. I sold it to a friend in 1980. And I've been trying to buy it back since. Its hard for me to let things go. Kevin

11th October 2010, 03:13 AM	#5
mr2racer diyAudio Member Join Date: Jul 2009	Eli, I see what you mean. The transformers in that picture are roughly twice the size of the Sherwood's. What about a copy of the Sherwood amp? Or, I believe Fisher used the 7868 and the 7591 tubes also. Are there any other circuits you could recommend? Kevin

11th October 2010, 03:22 AM	#6
dave_gerecke diyAudio Member Join Date: Dec 2007 Location: Vermont	Hello Kevin, I was just doing a quick scan through a couple of my schematics, I don't have the S8000, but I do have one of the S5000, which also appears to have used the 7868. I can email the S5000 schematic if you want it. Just drop me a PM with your email address and I will send it to you. Peace, Dave Gerecke

11th October 2010, 04:39 AM	#7
ronaldw441 diyAudio Member Join Date: Aug 2008	How about the output section of the Eico ST-70. Do a google search for the schematic.

12th October 2010, 01:58 AM	#9
wrenchone diyAudio Member Join Date: Feb 2004 Location: Silicon Valley	7591As have two sources for new parts - Electro-Harmonix and JJ. The NOS parts are getting pretty pricey. EH makes a new 7868, but the pins are larger than the standard Novar socket. I'm pretty happy with the EH 7591As in my "Kingfisher" amp. Come see it at BA.

15th October 2010, 12:41 AM	#10
mr2racer diyAudio Member Join Date: Jul 2009	BA?

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