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Re: Futterman H3 Blowing Fuse

Posted by AJ (A) on September 26, 2006 at 21:46:02

In Reply to: Futterman H3 Blowing Fuse posted by vacumtubes on September 25, 2006 at 22:15:06:

Hi, I've got one of these running on the ESL 57. Mine uses the 6fw5 octal which is cheap and plentiful...last I looked the 6fw5 and the 6hj5 are exactly compatable, one being a compactron the other octal..you can make the switch but I'm sure you can find the 6hj5's. Futterman used whatever worked or he had on hand. You can check the specs on TDSL. You can pick up 6FW5's all day long for $3-4..As for the 6hj5's they should almost give them away too...maybe you're not looking hard enough?

Careful on this amp the ac primary is not fused you could burn a transformer up quick if you don't know what you're doing

For example, my unit is labled with 7734 on the chassis for the upper screen regulator while infact ,it actually uses the 6DR7..they never changed the silkscreening on the chassis! A year or two after I got the amp I noticed the faint outline of what would have been a sticker covering up the 7734 label ... the sticker probably burnt up years before. I figured the 6DR7 thing out after the 7734 would glow cherry.

Before you make any judgements on this amp you MUST change all those lousy goodall caps with good quality film types.Also change the output electrolytics and powersupply caps... they are available from Allied or Mouser in the same form factor. I'm going to experiment with film caps on the output but it involves a bit of a modification to fit the larger diameter film cap and I just never got around to it.

Anyway, they do sound great on the ESL..finicky as hell to initially set up but once you get used to it .... it is a great amp...check out vintage asylum under "Joe Rosen" and Futterman for interesting reading.

Don't know what tubevib is saying I think he means impedance matching autoformers for your speakers ...you don't need this & has nothing to do with your problem. If you're running the Quads stacked just hook them up in series, just like Futterman himself recommended and enjoy.

I have Futterman's original bias and set up procedure on this amp in pdf. E-mail me through the board if you'd like a copy.

AJ

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