JohnW
pfm member
Paul,
Obviously I'd like to say that the cheaper amps will not compress the sound stage - but without the front end Tube circuit and VFET ClassA stage its hard to see how I can make them as good.
MDAC First Listen (part 00100111)
- Thread starter Rosewind
- Start date
- Status
Paul,
Obviously I'd like to say that the cheaper amps will not compress the sound stage - but without the front end Tube circuit and VFET ClassA stage its hard to see how I can make them as good.
JohnW
pfm member
You need current at high frequency's for the ESL panel - that's where the VFETs will shine
JohnW
pfm member
You and me both! - when you visits then you can listen for yourself
Remember I'm not happy that there is a difference in the first instance
JohnW
pfm member
A pure ClassA VFET design would be poor at driving low impedance loads - that's why I chose a Current dumping design for the Big VFET Amps - the VFETs then operate under benign operating environment where they see very little of the "real load" buffered by the beefier MOSFET Current dumping stage.
JohnW
pfm member
I must stress that I've only heard what might have been an early development of the NCores at Bruno home system which was new and alien to me.
The system was a SACD player + floor standing speakers and an UCD / NCore amplifier under development.
I'll never forget the power of the Bass, but the sound stage was just L/R with very little beyond the speakers - the Bass was so out of sync with the rest of the frequency range - so odd I still recall it today.
Someone else mentioned sound stage and Bruno's answer was that sound stage is just an illusion anyway - well by my book HiFi is about creating the "illusion" of a performance in ones home so Bruno's answer was disappointing and lost on me.
The constrained sound stage very much reminds me of the effects of sampling jitter in an ADC / DAC system, which is interesting as the UCD / Ncore modulation technique is inherently non linear (unlike a Triangle based Class D modulator).
As the Ncore modulation relies on a modulating the carrier frequency the very act of modulation cause as a phase change though the modulator only corrected by the feedback loop - so the modulator relies 100% on feedback for its baseband audio performance.
The Modulator relies on Frequency "Jitter" as its method of modulation, with the phase relationship of the baseband signal only restored by the actions of the feedback loop - this corrective action is not constant nor flat across the audio BW.
I'm sure Bruno would storm in and try and shoot me down with masses of theory why one cannot hear the modulation process - but I'm REALLY sensitive to whatever information the brain uses to process sound stage information, and without this information "correct" I don't hear recreated music as "HiFi".
I'm beginning to accept that some people are much more sensitive to "timing / Phase" information then others. I've met people who have zero interest in sound stage, while others like myself are acutely sensitive.
I have the same problem with computer games where the visual movements are not natural and within a short time of watching I feel nausea, dizzy and sick -where others are completely unaffected. We humans are not all made the same
and it stands to reason we have different sensual sensitivities.I plan to research this phenomenal on the MDAC2 platform where its advanced clock can in real time generate any Jitter distribution and spectral content.
JohnW, might be time to have a listen to the NCores if only to see what modern Class D can do, and I suspect might act as a good baseline. They really don't have an issue with staging or air qualities mentioned above - so long as the source has these qualities to begin with. Same with soundstage depth / life-like 'being there' qualities, so long as the source has it present.
As I've mentioned in the DIY section prior its really worth trying a very, very high quality source into the Ncores to really hear what they're capable of. I suspect the MDAC2 will be such a source. Even a decent £1k~ DSD Dac (Mytek 192) couldn't get them demonstrating their depth of capability. Took a £3k Auralic Vega to make me realise that... and this is why I think some people think of the NCores as 'meh' against other good amplifiers.
As I've mentioned in the DIY section prior its really worth trying a very, very high quality source into the Ncores to really hear what they're capable of. I suspect the MDAC2 will be such a source. Even a decent £1k~ DSD Dac (Mytek 192) couldn't get them demonstrating their depth of capability. Took a £3k Auralic Vega to make me realise that... and this is why I think some people think of the NCores as 'meh' against other good amplifiers.
ti33er
pfm Member
Thanks for your opinion on this Mr John ...I take it that you and Bruno are friends whom enjoy a healthy technical debate!
I am a sad individual that suffers a little OCD, maybe a lot(!) - I would really love my MDAC2 chassis to match my Amplifiers chassis too.
Of course it's all theory and loose as you explained, but could you not substitute other devices for VFETs in the cheaper design and still keep the Tube front end? I am no expert, but Transistors, or Triodes or even lots of other Tubes?
Perhaps at worst, unless it's 'sacrilegious' to do so, build me/us a pair of nc400 into a matching case such as the VFET case? Everything I read about nc400 talks of 3D soundstage, but a little 'neutral' which inhibits me diving in and investing as I dislike a cool/tepid sounding system (ROTEL/KRELL amplifiers are like this for me)!
Best regards
Paul
I am a sad individual that suffers a little OCD, maybe a lot(!) - I would really love my MDAC2 chassis to match my Amplifiers chassis too.
Of course it's all theory and loose as you explained, but could you not substitute other devices for VFETs in the cheaper design and still keep the Tube front end? I am no expert, but Transistors, or Triodes or even lots of other Tubes?
Perhaps at worst, unless it's 'sacrilegious' to do so, build me/us a pair of nc400 into a matching case such as the VFET case? Everything I read about nc400 talks of 3D soundstage, but a little 'neutral' which inhibits me diving in and investing as I dislike a cool/tepid sounding system (ROTEL/KRELL amplifiers are like this for me)!
Best regards
Paul
JohnW
pfm member
Thanks for your opinion on this Mr John ...I take it that you and Bruno are friends whom enjoy a healthy technical debate!
about 15 years ago I was heavily involved in ClassD design - but lost interest as digital modulators still have much to progress and technology was not ready. its a different story now - again the MDAC2 platform might lead onto a Digital amplifier.
The biggest single cost of the VFET amps is the chassis... They will not be cheap and you have to consider the electronics driving the front panel Display + touch buttons etc.
To do correctly, tubes do not lend themselves to mass production. I can consider tubes in the TDAC / VFET amps as I'll be hand building each unit - but for larger production Tubes are too troublesome.
Rosewind
Lost in Translation
You and me both! - when you visits then you can listen for yourself
Remember I'm not happy that there is a difference in the first instance
Hi John.
Looks like Rune and I will drive down to pick up the VFETs and MDAC2s when they are ready. I hope we won't have to lease a snow plough!
I am looking forward to listening to your MLs at LakeWest HQ and meeting you and Renata!I am with you with regard to sq when speaking of Vishays.
However, I think you avoided answering the cost side of my question. It would be nice to know how much fitting Vishay resistors will cost per 8x "extra" that are fitted to the MDAC2 board(s): 8x, 16x, 24x etc. I realise that just enough should be used to squeeze as much sq out of the MDAC2, and there I trust you with the decision.
Kind regards,
Peter
Steven Toy
Accuphase newbie
I must stress that I've only heard what might have been an early development of the NCores at Bruno home system which was new and alien to me.
The system was a SACD player + floor standing speakers and an UCD / NCore amplifier under development.
I'll never forget the power of the Bass, but the sound stage was just L/R with very little beyond the speakers - the Bass was so out of sync with the rest of the frequency range - so odd I still recall it today.
Someone else mentioned sound stage and Bruno's answer was that sound stage is just an illusion anyway - well by my book HiFi is about creating the "illusion" of a performance in ones home so Bruno's answer was disappointing and lost on me.
The constrained sound stage very much reminds me of the effects of sampling jitter in an ADC / DAC system, which is interesting as the UCD / Ncore modulation technique is inherently non linear (unlike a Triangle based Class D modulator).
As the Ncore modulation relies on a modulating the carrier frequency the very act of modulation cause as a phase change though the modulator only corrected by the feedback loop - so the modulator relies 100% on feedback for its baseband audio performance.
The Modulator relies on Frequency "Jitter" as its method of modulation, with the phase relationship of the baseband signal only restored by the actions of the feedback loop - this corrective action is not constant nor flat across the audio BW.
I'm sure Bruno would storm in and try and shoot me down with masses of theory why one cannot hear the modulation process - but I'm REALLY sensitive to whatever information the brain uses to process sound stage information, and without this information "correct" I don't hear recreated music as "HiFi".
I'm beginning to accept that some people are much more sensitive to "timing / Phase" information then others. I've met people who have zero interest in sound stage, while others like myself are acutely sensitive.
I have the same problem with computer games where the visual movements are not natural and within a short time of watching I feel nausea, dizzy and sick -where others are completely unaffected. We humans are not all made the same
I plan to research this phenomenal on the MDAC2 platform where its advanced clock can in real time generate any Jitter distribution and spectral content.
Accuracy of timing and phase information are important to my ears. This is not only important for soundstage (which I do think is inportant too, btw) but also for things like 'timing,' 'texture,' harmony, melody and decay into space.
fred sonnen
pfm Member
Are you thinking about a license production of these rising amplifiers? You mentioned somethink about the upcoming mdac2...
perhaps it could be a solution to produce the pcb without the tubes and install them during the quality check process. just for the pfm/ mdac2 owners / customers....
I would be realy interested in 4 - 6 mono hybrid amplifiers ;-)
amershamman
pfm Member
Hi John,
I've just paid my L2 4th Development Installment - I have'nt been sent a reminder about it, but I think payment is due around now.
Thanks again,
Chris
I've just paid my L2 4th Development Installment - I have'nt been sent a reminder about it, but I think payment is due around now.
Thanks again,
Chris
JohnW
pfm member
Chris,
Thank you for the payment - Renata will send confirmation in the morning.
We have yet to send official request for the 4tgh installment as I've just been to busy on testing the MDAC2 PCB.
Our imitate concern is to have a concise number of PCB's required for production - hence the recent effort to confirm MDAC2 upgrades for MDAC1 Toy / Fusion owners
JohnW
pfm member
We would not use tubes for in any "mass produced" amplifier design due to the problems insuring constancy and stability.
I'll use Tubes in the VFET and TDAC as I'll hand build / test each unit so can be assured that they will meet specifications and the hopefully trouble free performance.
JohnW
pfm member
I'm afraid the word "timing" has different terminology within the HiFi industry - I believe your referring to "timing" as in "timing of the Bass" getting your foot tapping - I'm not sure if this has any direct relationship with phase....
JohnW
pfm member
The PCB's are built "At Cost" this includes the Vishay resistors. I don't have a direct price for the Vishays yet so cannot comment - although they should be say 40% - 50% cheaper in "bulk" then online pricing.
davidjt
pfm Member
.....which, last time I looked at RS (if I'd found the right ones?) was around 10 quid a pop.
ti33er
pfm Member
- Status