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RE: Q about Thorsten's 417 DC 45 amp

Posted by Thorsten (M) on August 11, 2010 at 10:49:16

In Reply to: Q about Thorsten's 417 DC 45 amp posted by dhsettim on August 7, 2010 at 14:01:44:

Hi,

> I have a pair of Thorsten's 417 DC 45 monoblocks.

They are probably more Gordon Rankin's than mine, I just translated his approach as posted here into a Loftin White Circuit.

> I want to try replacing the 10K 417 anode load with
> a CCS to see what it sounds like.

Go for it. Make sure the CCS is adjustable and adjust for the same grid voltage on the 45.

> I would then like to try cathode negative feedback.
> This is normally done by grounding the output valve
> through the OPT secondary, but with Thorsten's design
> I'm not quite sure if it can be imlimented and if so where.

First, with the cathode at 186V with a fair bit of current behind linking the secondary in series with the cathode is a VERY BAD idea.

You could just connect the Cathode bypass capacitor to the secondary, but then you need to remove the "WE Connection" Capacitor and the circuit would possibly not work as well.

With a 45 you have so little gain, there is not a lot of feedback to gotten that way anyway.

So my suggestion, just leave it out.

TBH, there ain't no much ta tweak on thata circuit, withouta turning it into completely another kettle of fish, and that, as they say is another story.

If you must, bypass all the Film Cap's with something nice, maybe tinfoil & teflon, or silver & mylar or whatever floats your boat. Or just get Audio Note Silver foil cap's and silver wired permalloy cored audio note transformers and rebuild from scratch (and sell a few organs to fund the purchases).

Ciao T
Thor

At 20 bits, you are on the verge of dynamic range covering fly-farts-at-20-feet to intolerable pain. Really, what more could we need?

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