MDAC First Listen (part 00110000)

[timola]

Until late October I have a couple of PHD students who will be avaible to upgrade MDAC's with the boards if there is any interest. .

Professor John, I'm interested in having my MDAC upgraded by your post-grad research team...

I don't have another DAC so would like to send my MDAC when you have the Superior PCBs ready to rock&roll....please let us know.

 

[fusion5]

When I put the original board (with the broken USB port) back into the silver chassis, I noticed one small bulged cap and about four with domed top.

I moved the Fusion board back to the black chassis and noticed a bulged cap on that one, too

 

[misterdog]

I've been running mine without the case but that is obviously unsatisfactory in the long term.
( I know what Paul is going to say in response )

I have a team of post grad. cabinet makers on standby, just have to do some listening tests to see which plywood provides best SQ.

 

[misterdog]

are you still planning on creating a simple board to be able to close the MDAC case and power it with 3 Calex PSUs ?

I suspect there are no more than 6 (3xCalex) PSU owners, so it is hardly worth making a bypass board.

The Calex supplies are still available as are other PS options but at £ 70/80 each, plus case, etc.


( I had the option to buy the last 20 Calexes for £ 8 each )

If there were sufficient interest in a fully regulated 5 rail power supply I'm sure one could be arranged by the DIY community.

 

[fred sonnen]

I had the option to buy the last 20 Calexes for £ 8 each

If there were sufficient interest in a fully regulated 5 rail power supply I'm sure one could be arranged by the DIY community.

If the mdac2 swep Boards are available and johnw is saining the calex psu are the basement for that, I am in.
Regards
F.s.

 

[davidjt]

I have a team of post grad. cabinet makers on standby, just have to do some listening tests to see which plywood provides best SQ.

I'll take one. Assuming you're not growing the trees from seed.

 

[Richard Kimber]

I have a team of post grad. cabinet makers on standby, just have to do some listening tests to see which plywood provides best SQ.

Misterdogwood, presumably,

 

[highfi]

John, considering that my normal listening levels with MDAC are -36 to -21 (usually towards the former), will there be some provision with FDAC to ensure optimal levels for me? Thanks!

 

[JohnW]

With the new hyperstream 2 modulator design of the ES9028 you don't need to worry about the Digital level setting.

I listen up to -10dB on some recordings so the 2Vrms output seems about correct.

To be honest, the problem is with too much gain in the power amplifiers - rather then the DAC output level. Gain is not for free, and the amplifier would sound better if it had less gain.

The VFET and 8200MB+ will be gain matched to the MDAC /FDAC.

 

[JohnW]

As I recall you wrote it would be a quick step, are you still planning on creating a simple board to be able to close the MDAC case and power it with 3 Calex PSUs (leaving owners of such solution with the need to find a suitable housing and connector to plug into the back of the MDAC)?

Yes, once I have a better insight into the PSU option for the MDAC, then we will design a relevant internal PSU card. it might be the full "version" of the superior upgrade board is not so sensitive to the PSU quality - or it might be worst...

I'd just like to insure that I can insure that anyone's whose interested can experience the SQ that Ian and I heard here with the early rats nested "superior" MDAC.

 

[highfi]

With the new hyperstream 2 modulator design of the ES9028 you don't need to worry about the Digital level setting.

It would be great if you could expand on this briefly.

I listen up to -10dB on some recordings so the 2Vrms output seems about correct.

Fair enough, that’s standard output level.

To be honest, the problem is with too much gain in the power amplifiers - rather then the DAC output level. The VFET and 8200MB+ will be gain matched to the MDAC /FDAC.

The FDAC won’t have any kind of attenuation or similar feature for use with other power amplifiers, then?

Gain is not for free, and the amplifier would sound better if it had less gain.

Perhaps that would apply to FDAC, too? Since you’ll be inspecting each unit individually before shipping, could the output of a unit be reduced perhaps? ATC power pack has 1VRMS input sensitivity and <10Kohms impedance.

It’s a MOSFET design by the way, so FDAC/ATC owners will be looking at (listening to) a full MOSFET system!

 

[iansr]

Yes, once I have a better insight into the PSU option for the MDAC, then we will design a relevant internal PSU card. it might be the full "version" of the superior upgrade board is not so sensitive to the PSU quality - or it might be worst...

I'd just like to insure that I can insure that anyone's whose interested can experience the SQ that Ian and I heard here with the early rats nested "superior" MDAC.

I'll just mention one example. One of the tracks was a relatively short drum solo, just a few minutes. I have never heard drums reproduced as realistically by a hi fi system before. It's a cliche but in this case absolutely accurate; if you closed your eyes you would think the drummer and his kit were right there in the room with you. WOW was definitely in order. And bear in mind that John's current amps are not playing in the premier division.

 

[BigDog]

I'll just mention one example. One of the tracks was a relatively short drum solo, just a few minutes. I have never heard drums reproduced as realistically by a hi fi system before. It's a cliche but in this case absolutely accurate; if you closed your eyes you would think the drummer and his kit were right there in the room with you. WOW was definitely in order. And bear in mind that John's current amps are not playing in the premier division.

Well, that should keep everyone excited!

BTW, was the drum solo track something commercially available?

 

[iansr]

It was a track that John had picked up somewhere along the way and he couldn't remember who the drummer was or any other details.

 

[JohnW]

I'll just mention one example. One of the tracks was a relatively short drum solo, just a few minutes. I have never heard drums reproduced as realistically by a hi fi system before. It's a cliche but in this case absolutely accurate; if you closed your eyes you would think the drummer and his kit were right there in the room with you. WOW was definitely in order. And bear in mind that John's current amps are not playing in the premier division.

Yes. even for me that was a "wow" moment the system:-

Martin Logan Aeons (MKII)

Single Rel Q200E subwoofer, set to about 45Hz and very low output level, feed from the Left channel Power Amps output.

Heavily modified "prototype" Audiolab 8200M's with Balanced input (weakest link in the system).

Superiors MDAC with a "rats nested" "superior" modification using MDAC's own output stage + Philips Blue PP Caps, Clarity Caps + x8 Vishay Bulk foils (x4 680R & x4 47R)

3x Calex PSU's

Detox with Sony Viao hand held Computer

 

[JohnW]

Superior PCB files have been summit to the PCB vendor - I ordered x4 pcs for the first batch.

1 for internal use and testing

1 for Superiors unit

leaving 2 "spare" boards...

 

[fusion5]

Well, if you need to open my unit anyway

 

[JohnW]

Well, if you need to open my unit anyway

Michael

Question is do you want the full package of Vishay Bulk foil resistors? - nows a good time to buy from UK stock!

I see a few combinations,

Bulk foils used in all positions 52 resistors:-

680R x4

47R x4

33K x8

100R x16

1.2K x4

470R x8

33R x8


Reduced cost option 20 resistors:-

680R x4

47R x4

33K x8

1.2K x4


Basic 12 resistor option:-

680R x4

47R x4

1.2K x4

Or just using standard "cheap" thin film MELFs...

 

[fusion5]

Michael

Question is do you want the full package of Vishay Bulk foil resistors? - nows a good time to buy from UK stock!

I see a few combinations,

Bulk foils used in all positions 52 resistors:-

680R x4

47R x4

20K x8

100R x16

1.2K x4

470R x8

33R x8

If the full package is a viable option, then it might be a good idea to check this out. 52 resistors = GBP445,40. Do you know if the MDAC discount is still active?

Or just using standard "cheap" thin film MELFs...

lol

Edit: Reduced cost option = GBP176,04 and Basic option = GBP102,68

 

[JohnW]

It would be great if you could expand on this briefly.

The original ESS9018 has a couple design issues that effect the performance of the Digital Gain stage - these have been corrected in the new ES9028/38

Fair enough, that’s standard output level.

Yes, 2V RMS is industry standard - has been since CD was launched.

The FDAC won’t have any kind of attenuation or similar feature for use with other power amplifiers, then?

The FDAC has digital attenuation - which is higher quality then can be achieved with any other method on the FDAC design. Due to the FDAC's unique topology, reducing the gain impacts other factors (Analogue stage Phase and Gain Margins, RF LPF etc) - its a trade off between many interrelated (and opposing) considerations - part of the Superior testing is to sonically optimise these "considerations".

Perhaps that would apply to FDAC, too? Since you’ll be inspecting each unit individually before shipping, could the output of a unit be reduced perhaps? ATC power pack has 1VRMS input sensitivity and <10Kohms impedance.

Due to the FDAC's unique design its no possible to change the analogue gain without impacting 4 carefully optimised circuit perimeters.

Your speakers are rated 1Vrms - so the FDAC at 2V RMS is only +6dB higher in level.