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MDAC First Listen (part 00100001)

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JohnW said:
I'd not Mix and match amplifier types, I'd worry about the phase relationship between amps.

I've found Bi-Wire to be beneficial - well at least it has an effect on the SQ - for better or worst depends upon the systems balance in the first instance.

The Amps dumper section, I'll most likely parallel 6 output devices so there will be masses of Peak current.
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John, that sound great!

Please add me to the list for a pair.
 
John, i am also very interested. I decided to buy a new amplifier some days ago... Now i have a Cambridge 840W, but i am not really satisfied. Could you PM me estimated price for a pair of amps please?
Cheers, Uwe
 
John,

I've asked for details three pages ago but it might be out of your forum horizon. I'm also interested for your amp project. Could you pm me the details.

Br/
 
JohnW said:
The Dumper are NOS vertical Hitachi MOSFETs, again limited stock (I still have same from Pink Triangle days).s...
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If the output dumper stage is not dynamically biased, wouldn't it be better to use lateral FETS as the dumpers?, they also have the advantage of being quite cheap and readily available.
 
russel said:
If the output dumper stage is not dynamically biased, wouldn't it be better to use lateral FETS as the dumpers?, they also have the advantage of being quite cheap and readily available.
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Russel,

:) I've not gone much into the fine details, but the planned "Dumpers" are actually "Non Switching" so as to not present an abrupt non linear loading to the VFET ClassA stage - it makes a massive improvement over the Quad Class "C" dumper stage whose non linear loading around the none symmetrical "crossover" region negatively effects the ClassA stage (the Quad Class A stage has an inherently high impedance and ironically relies upon feedback to reduce to a practical level).

These amps will be an interesting and truly unique design topology :)
 
JohnW said:
Russel,

:) I've not gone much into the fine details, but the planned "Dumpers" are actually "Non Switching" so as to not present an abrupt non linear loading to the VFET ClassA stage - it makes a massive improvement over the Quad Class "C" dumper stage whose non linear loading around the none symmetrical "crossover" region negatively effects the ClassA stage (the Quad Class A stage has an inherently high impedance and ironically relies upon feedback to reduce to a practical level).

These amps will be an interesting and truly unique design topology :)
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Be interested to see the topology but I guess you are keeping it secret. Have you looked at the transfer curves of the 2SJ77 2SK214?, I think they look quite nice. They might possibly be useful as the class A stage although it would require a bit of a redesign. Not quite a cool as power JFETS though.
 
I don't know the 2SJ77 / 2SK214, I'm planning to use the 2SJ118 & 2SK413 based upon experience many years ago when my father spent a couple of years developing an amplifier for Pink Triangle - in many ways this design will be an ode to him :)

Guess, I'd not mind to show the circuit topology so long as it was kept secrete, I'm most sensitive about the tube stage anyway I guess...I have over 500 hundred amplifier simulation files I'l have to go though and combine the best circuit sections to put together the complete amplifier design.
 
JohnW said:
I don't know the 2SJ77 / 2SK214, I'm planning to use the 2SJ118 & 2SK413 based upon experience many years ago when my father spent a couple of years developing an amplifier for Pink Triangle - in many ways this design will be an ode to him :)

Guess, I'd not mind to show the circuit topology so long as it was kept secrete, I'm most sensitive about the tube stage anyway I guess...I have over 500 hundred amplifier simulation files I'l have to go though and combine the best circuit sections to put together the complete amplifier design.
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The 2SJ77/K214 could only be used for the class A correction amplifier, the J118/K413 are much higher power, its just they are quite linear at currents in the 30- 500mA range, as they are lateral FETs there is no big Vgs threshold and nasty square law start to it. Thanks, no problem signing an NDA if you need one, or just an email saying I promise not to divulge etc.
 
Hey hey hey. It's going way too fast for me at the moment. Can't one be allowed to have a bit of summer holiday without the amp project and TDAC suddenly materializing at a staggering speed? Come On! I need some time to think and save up for this. Anyway, Christmas is too early for me to invest in a unique amp. Better wait for the T-Dac.
Rune: seems like there will be more than one MDAC2 L3 in Denmark.
Cheers,
Peter
 
JohnW said:
Kevin,

Forgive me for asking (as Renata's "busy" shopping...), but do you have a Toy / Fusioned unit? if you do then you qualify for an "At Cost" MDAC L1 (You would just need to pay the development difference once they are requested for the other level builds).

If your not a Toy / Fusion MDAC owner then you can join the MDAC2 project by paying the GBP300 installment. :)
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John,

Payment has been made this evening. Thanking you :)

Kevin
 
Rosewind said:
Hey hey hey. It's going way too fast for me at the moment. Can't one be allowed to have a bit of summer holiday without the amp project and TDAC suddenly materializing at a staggering speed? Come On! I need some time to think and save up for this. Anyway, Christmas is too early for me to invest in a unique amp. Better wait for the T-Dac.
Rune: seems like there will be more than one MDAC2 L3 in Denmark.
Cheers,
Peter
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Peter,

Yes, indeed :) The Amp project has started to come together - well its a higher end unit but I'm really looking forward to the VFETs + Tube, and to see a new Current dumping amplifier :) - its such a shame that Quad have chosen to flog the same design for so long, their current designs can be traced back to the original 606.
 
russel said:
Be interested to see the topology but I guess you are keeping it secret. Have you looked at the transfer curves of the 2SJ77 2SK214?, I think they look quite nice. They might possibly be useful as the class A stage although it would require a bit of a redesign. Not quite a cool as power JFETS though.
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Oh BTW, I plan to use series connected 4 pole T-Caps for the PSU - I had a listen on a bench amp and I was impressed - what's been your experience?

While they are expensive, there is no question an Amp of this quality deserves them - I wonder why they are not more popular?
 
This amp sounds interesting... I'm getting tempted, depending on the price per stereo pair that is. Would it be possible to get an estimate by pm?
Cheers,
Eiffel
 
JohnW said:
Oh BTW, I plan to use series connected pole T-Caps for the PSU - I had a listen on a bench amp and I was impressed - what's been your experience?

While expensive, there is no question an Amp of this quality deserves them - I wonder why they are not more popular?
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Series connected T-networks, nice!. I use them and like you I wonder why they are not the de-facto standard PSU cap for hi end amplification, price and fashion perhaps? I have mentioned them here and on DIY audio before but not many people have heard of them. Definately worth the extra money in my view.
 
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