PS transformer made for an OTL?

Posted by Dan on May 30, 2001 at 21:46:31

Hi Guys,
Last weekend I came across a weird transformer, which I bought for 10$ used. Its a huge monster, 70 lbs or something, with great steel frame. Secondaries are

460-0-460 @ 100 mA
4 x 6.3V @ 8 A (!)
5V @ 6 A
5V @ 3 A

With 28A of 6.3 it seems like a natural for an OTL amp. Maybe its a call for me to join the fold again. If I build one, I promise to run it full range Mark! :) Now I'm thinking of doing something unusual, and need some ideas.

I have these 108 dB speakers at 12 Ohms flat, so I only need a few watts, and really less than a watt.

Now, the three constraints are
A) Electricity costs a fortune in CA, and its summer, so the less tubes the better.

B) Each of my full range drivers cost about 1500$, so I have to be REALLY protective of them, so I don't want to trust a fuse for a 6336 for example.

C) I'm collecting too many amp topologies, so want to keep this fairly cheap :) An OTL is a natural, because I don't have to buy expensive iron.

I thought to put 1 6336 per phase, 4 total, but can't take the risk of one going down (unlikely, but still). Or, perhaps it can drive a PP transformer (I know, I know) to isolate the two sides. Or, what about 1 6AS7 per phase, with a ZERO? I've forgotten the power calculations for an OTL. How much would one 6AS7/phase give me?

I'm thinking of a single, 6H30pi as a driver. Its got a nice low plate impedence, and really knows how to push. Paul put the bug in my ear about this as an OTL driver tube. The HV from the transformer above can be tube rectified, and LC knocked down with some big power resistors for the driver supply. I can pick up some isolation transformers for the output stage.

This can be really cool, and I can report how the 6H30pi driver compares to the 12SX7 (I still have a bunch) Thoughts?

Dan

This post is made possible by the generous support of people like you and our sponsors:

Topic - PS transformer made for an OTL? - Dan 21:46:31 05/30/01 (17)

Re: PS transformer made for an OTL? - Paul Speltz 21:32:24 06/02/01 (1)

Two Tube OTL - Paul Speltz 21:39:14 06/02/01 (0)

And now for something completely different... - mark 12:06:31 05/31/01 (14)

Question for Mark - Allan 00:26:31 06/01/01 (7)

Re: Question for Mark - mark 07:40:34 06/01/01 (6)

Thanks Mark - Allan 15:31:58 06/01/01 (5)

Re: Thanks Mark - mark 20:52:40 06/01/01 (4)

WOW! - Allan 03:37:54 06/02/01 (3)

Everything's gone to pot(s)... - mark 06:38:05 06/02/01 (2)

Re: Everything's gone to pot(s)... - Allan 08:20:41 06/02/01 (1)

Re: Everything's gone to pot(s)... - mark 10:45:53 06/02/01 (0)

Re: And now for something completely different... - Dan 13:29:56 05/31/01 (5)

Re: And now for something completely different... - mark 17:21:29 05/31/01 (4)

Re: And now for something completely different... - Dan 18:24:31 05/31/01 (3)

Re: And now for something completely different... - mark 18:34:10 05/31/01 (2)

Re: And now for something completely different... - yves 19:39:05 05/31/01 (1)

Re: And now for something completely different... - mark 07:43:35 06/01/01 (0)

You can not post to an archived thread.