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WTB: two OPT's for p-p EL84's

I am looking for two new or used high quality OPT's for push-pull EL84's (6BQ5's) for a pair of 10 -15 watt monoblocs I am planning to build (the "Mullard 5-10" circuit.) 8,000 ohms plate to plate, UL type preferred (43% screen taps), but others considered. Please email me at "analogdino 'at' rogers 'dot' com" (formatted correctly.) Ideally, I'd like to find these in the Greater Toronto Area (GTA), Ontario, Canada, to avoid shipping costs, also customs costs if from outside Canada, but this may not work out. Thanks for all replies Cheers, Roger GTA (Toronto), Canada.

Reply to
Engineer
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they do Sowter stuff (excellent), and since they are US based they probably arn't too expensive to ship from.

Old Doc Sowter was a cool guy, I'm think he invented Mumetal in the days of Flash Gordon, and Tom& Jerry

martin

"Wales is a big welsh-shaped rain collection device"

Reply to
martin griffith

I'll second Sowter for transformers ( if you really have to use them - which valves do for output ! ). First class product. Probably the UK equivalent of Jensen for low level stuff too. I've found their audio 'line level' transformers amongst the very best.

Another couple of names of old - now long gone I think - are Partridge and Gardner transformers in the UK. I forget wich brand 'Orange' valve amps used but it was one of them.

Did Jensen ever do OPTs ?

Btw - if you know your stuff you can design your own OPTs. Go for a toroidal core and you'll get amazing bandwidth compared to EI and better linearity IIRC.

Graham

Reply to
Pooh Bear

Hammond Mfg still does these, available out of the 'Sonic catalogue with a ~2wk lead time.

1608, 1650f, all have 40% screen taps.

Larger and potted types may also be available - never ordered them.

RL

Reply to
legg

I'm not really a toob man myself actually - but I learnt my early electronics on them. Well.. kinda half and half with transistors too.

I knew someome who wound them. Having looked into it, the basic equations for practical transformer design are quite simple but rarely well known.

Graham

Reply to
Pooh Bear

On Mon, 30 May 2005 02:17:01 +0100, in sci.electronics.design Pooh Bear wrote: snip

I'm not a Toobe man, (although I *must* get my Quad II's up and running one day.and rebuild my ESL's)

Any ref's on using a torroid for a OPT?

martin

"Wales is a big welsh-shaped rain collection device"

Reply to
martin griffith

Check out Plitron, also in the GTA.

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RL

Reply to
legg

Hello Graham,

Or use pot cores. I also prefer toroids but that gets old when you have to wind a gazillion turns onto them for the tube side.

DC saturation is one concern, must stay away from that or things become non-linear. Even in a push pull configuration there can be a residual DC imbalance. Then there is the old habit of shooting for four times the impedance at the lowest desired frequency. Doesn't always work if you can't get enough BW for the upper end but with ferrites I found that to be quite easy.

A good starting point is to see how much inductance a commercial OPT with a good reputation affords.

Regards, Joerg

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Reply to
Joerg

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