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Old 24th July 2014, 09:19 AM   #51
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Thanks Hugh, I read about your loss and you have my condolences. The Dartzeel appears extremely high-end from the exterior but the component count is very small on the schematic.

Ian, thanks for that reference, you've given me some more reading material to ponder.

I will keep plugging away and update when I think I have something interesting to add...
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Old 24th July 2014, 09:24 AM   #52
Mooly is offline Mooly  United Kingdom
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If you are looking at the Nad 310 then don't overlook another of its secrets. Look at the output and R255/C225 and R256/C226.
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Old 27th July 2014, 01:12 AM   #53
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Mooly, WOW... there is intentional cross-conduction between the two channels

The schematic I posted on the last page seems to have generated a small amount of interest. A very clever, helpful, Australian designer has been in contact with me to discuss some of the finer details (and for the avoidance of doubt it is not Hugh, although he certainly fits all those critera!).

As is often the case, these suggestions have led to further research and new ideas, but these will wait for another project. I want to keep this "very simple" and I still think it meets that criterion.

I'm still working on the board layout - obsessively - I want this to better the last.

In the meantime here's the latest schematic. I got the idea for R22 from some of OStripper's designs ("VAS abuse - his words ). Seems to increase H2 and slightly lower H1.
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Old 27th July 2014, 03:52 AM   #54
Bigun is offline Bigun  Canada
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Looking good, I like this approach !

(R22 - is a good idea, nested feedback, you have it in TGM8 too)
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Old 27th July 2014, 07:24 AM   #55
Mooly is offline Mooly  United Kingdom
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Quote:
Originally Posted by Ranchu32 View Post
Mooly, WOW... there is intentional cross-conduction between the two channels
Yes Another of its little "subjective performance secrets"
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Old 27th July 2014, 01:23 PM   #56
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Looking good, I like this approach !

(R22 - is a good idea, nested feedback, you have it in TGM8 too)
I'm taking a break from my Blameless MkII. The component count has skyrocketed (the current design is more complex than the last schematic I posted...) and its making my head hurt.

Having some fun with this one by trying to optimise - instead of minimise - the THD.

The gentleman I spoke of earlier is Richard McDonald, an Australian amplifier designer. Richard has kindly shared some information which "does not compute" with what I have learnt from reading Self, Cordell et al. I'm still trying to process it.

I've not heard Richard's line personally and first became aware of them around a year ago when I bought a pair of floorstanders from Adelaide Speakers (Quasimodo Stereo Amplifiers). Edward, the loudspeaker builder behind the brand loves to chat and was very complimentary of Richard's product. I'm extremely happy with my speakers so I'm inclined to trust his judgement in audio matters generally.

It really is a small world (here in Australia anyhow!).
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Old 27th July 2014, 11:41 PM   #57
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Christian,

Richard and I are friends and have been collaborating with amp design for 15 years.......
Lovely guy, very active, and with a wonderful ear too. He and I created the AKSA in 2000.

Hugh
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Old 28th July 2014, 12:36 AM   #58
Bigun is offline Bigun  Canada
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It seems to me that Hugh and Richard are still keeping close - there is something in the air in Australia that keeps lots of good ideas flowing.
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Last edited by Bigun; 28th July 2014 at 12:45 AM.
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Old 28th July 2014, 12:44 AM   #59
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I'd add a resistor (e.g. 82R) in the power rails with cap to ground, to isolate the front end from the power output stage.
This will also help with hum with little or no signal.
I did this with my mosfet amp and it is dead silent with no signal.
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Old 28th July 2014, 01:05 AM   #60
AKSA is offline AKSA  Australia
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there is something in the air in Australia that keeps lots of good ideas flowing
It's in the air everywhere, Gareth, OCD in modern times, 'nerdiness' back in the eighties.

Most of us in the SS forum are afflicted with this wondrous affliction. I find amp design the most intellectual pursuit I know, certainly it suits me.

Ciao,

Hugh
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