audio-talk

Nick did a fancy regulated supply for Colins GM70 monoblocks but I think the HT was higher than you require.

I might have a diagram of it somewhere, if Nick or Colin don't mind I will dig it out for you.

Ali Tait wrote:Dipole sub wasn't it?

Sounds about right, used a Celestion driver from memory.

If I remember tomorrow I will rummage through my old supplements.

Can't help with non BG power supplies !

If BG = Black Gate (as in EXPENSIVE capacitors) then all my power supplies are non BG.

From what I have read over the years subwoofers to partner the ESL speakers are very difficult to get right.

I seem to remember Noel Keywood built one powered by a Quad 606 amp, not sure if it was in one of the Hi-fi World DIY supplements.

With power supplies it often depends on what mains transformers you have to hand !

My preference now, if starting with nothing, would be to go choke input (L - C - L - C ) and use Duncan Amps PSU designer to work out what secondary voltage you need.

Have you got any mains transformers to hand ?

Mike H wrote:
Too much babycham

.

You is not a babycham boy is you ?

Don't let DTB read this.

Seems my first attempt at 6DN7 DRD was thwarted by a piece of bum wiring. I noticed it as I was about to undo the changes.

Now I have modded both amps as per my first calculations and they are playing at the moment.

After my listening session I will put one on the bench and take some measurements.

I'm going to try the chokes without DRD as a first step, and will come back to the DRD thing at a later date, after the bwain transplant.

I'm assuming of course your bias for V2 is not enough with the DCR of those chokes? Or is it too much? Remind me (forgotten!) output is 6DN7? And the driver is what? . The same ! half is driver (pins 4,5 & 6) and half is output (pins 1,2 & 3) When I attempt "sums" I really do suff...

Doing my measurements again, stage 1 is only drawing 2.6ma (through the existing 120K resistor), so at that current the 200H choke will only lose 20V. So 50 + 20 =70 - 13 =57V and 64V at cathode 2. So need a potential divider to replace the 1.5K so the suggestion you made for DTB (1.3K + 200R) shoul...

So, if anode 1 is the same as grid 2 (51V) and cathode 2 is 64V the bias is -13V ?

So the 200H chokes I have will need 112V - 13V =99v

So still not enough for DRD with these particular chokes.

Might just scrape through with the Hammonds.

Time for the calculator.

Nick wrote:Actually I was wrong, its v1 anode + ( choke v drop - v2 bias )

I was confused enough before !

The e-bay DAC kit I use came with a transformer. At the price they charged it was a bargain.

My two Hammond 150H are 3.3K ohm but even that is too high when I worked it out.

Will use the 200H without trying DRD first.

Also I will check and see if I can find the DCR of Tims 200H chokes.The ones Andrew sent me are centre tapped so may have a different DCR.

My brain has started to hurt. Looking at 200H anode choke and DRD. On the first anode of 6DN7 I have 51V. The 200H choke has a DCR of 7.6K so at 8ma will lose 61v So if I want to go DRD and keep anode at 50 (ish) volts the cathode 2 must be higher than 112V (51 + 61). But cathode 2 is only 64V So is...