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Old 11th October 2010, 01:33 AM   #1
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Default 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
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Old 11th October 2010, 01:39 AM   #2
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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.
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Old 11th October 2010, 02:27 AM   #3
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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
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Old 11th October 2010, 02:53 AM   #4
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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.
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Old 11th October 2010, 03:13 AM   #5
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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
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Old 11th October 2010, 03:22 AM   #6
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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
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Old 11th October 2010, 04:39 AM   #7
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How about the output section of the Eico ST-70. Do a google search for the schematic.
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Old 12th October 2010, 01:43 AM   #8
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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.
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Old 12th October 2010, 01:58 AM   #9
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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.
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Old 15th October 2010, 12:41 AM   #10
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BA?
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