JohnW
pfm member
MDAC2 only requires x4 ZFoils (and x4 more for the analogue attenuator versions) ... Might have been x32 for the original MDAC...
I'd worry more about the capacitors then resistors of an XO.
MDAC First Listen (part 00100001)
- Thread starter stellablues
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MDAC2 only requires x4 ZFoils (and x4 more for the analogue attenuator versions) ... Might have been x32 for the original MDAC...
I'd worry more about the capacitors then resistors of an XO.
Presumably fusion spec will require more?
That is at least what i thought.
JohnW
pfm member
The tube is used in the circuits "Front end" differential stage - which is subjected to the RF energy from the Array DAC - the output devices are MOSFETs (As with MDAC2).
Actually I'm just investigating the thermal stability of the MDAC2's Mosfet output stage - which at the 150mA or so ClassA bias current has a negative temperature coefficient.
ATM, the initial Bias current is reduces as the output devices warm up - this is a useful effect as this reduces the "Warm up" time - once the heatsink reaches thermal equilibrium the bias current drops to the wanted 150mA idle current.
My idea is to use the VFETs in place of the MOSFETs in the SE TDAC design.
JohnW
pfm member
The MDAC has a more complex analogue LPF filter stage which required the larger number of Vishay bulk foils - these are in the "direct signal path".
Part of the design effort for MDAC2 was to reduce the required complexity of its Analogue filter design which now only requires 2 resistors per channel (plus an extra 2 used for gain scaling).
I'll investigate using the Vishay bulk foils in the actual Gain stage circuit of the MDAC2 as they are already used in its the much simplified LPF (for L2 / L3).
Morph3R
pfm Member
Does this mean difference between default MDAC2 (a.k.a Toy) and full Fusion version will be only 4 (2 per channel) bulk foils?
JohnW
pfm member
Morph,
I'm going to try the Fusion resistors in the other positions of the MDAC2 Analogue circuit not just the Analogue filter as is the case of the original MDAC Fusion upgrade.
Ok thanks John never realized the outlet stage on the Tdac had mosfets I guess as a statement design it should feature the best devices available.
What if anything will be transferable from the MDAC2 ,as far as parts are concerned, into the TDAC or will it be a complete separate unit.
What if anything will be transferable from the MDAC2 ,as far as parts are concerned, into the TDAC or will it be a complete separate unit.
Hi! Is someone here able to confirm that M-DAC optical output is working correctly with firmware vA.10? I've connected it to an external DAC which recognizes the bit-depth and frequency of the signal correctly but there's no sound whatsoever.
I have:
1) Tested the same external DAC input with another digital source - working
2) Tested with two different toslink cables - no difference
I haven't tested this setup before with any other firmware versions so I can't tell if it's a software or hardware issue. My digital output settings in M-DAC are configured as Coaxial S/PDIF & Optical S/PDIF.
I have:
1) Tested the same external DAC input with another digital source - working
2) Tested with two different toslink cables - no difference
I haven't tested this setup before with any other firmware versions so I can't tell if it's a software or hardware issue. My digital output settings in M-DAC are configured as Coaxial S/PDIF & Optical S/PDIF.
iansr
pfm Member
Google Earl Geddes and have a read of what he has to say about how to get the best bass response in a domestic sized room, its fascinating; essentially the more bass sources the better, but your mains plus 3 subs works well. His conclusions are based on acoustical science, not snake oil vapour.
Thanks John for the quick reply!
I've tried with Squeezebox Receiver connected to a coax input of M-DAC and my TV connected to an optical input of the M-DAC. Both of them work when using analogue outputs of M-DAC.
Ok. I really need some of the features from A.09 (like functional discrete remote codes) so I'd be happy to first hear if someone has similar setup working with A.10.
I now tried this but there's no difference.
Second optical input port? As I mentioned above I've tried with an optical and a coax input and they're both working with analogue outputs. Shouldn't all the inputs be routed to the digital optical output?
I'm not able to try the digital coax output since my external DAC has only optical S/PDIF input.
I've tried with Squeezebox Receiver connected to a coax input of M-DAC and my TV connected to an optical input of the M-DAC. Both of them work when using analogue outputs of M-DAC.
Ok. I really need some of the features from A.09 (like functional discrete remote codes) so I'd be happy to first hear if someone has similar setup working with A.10.
I now tried this but there's no difference.
Second optical input port? As I mentioned above I've tried with an optical and a coax input and they're both working with analogue outputs. Shouldn't all the inputs be routed to the digital optical output?
I'm not able to try the digital coax output since my external DAC has only optical S/PDIF input.
JohnW
pfm member
The SPDIF Optical output with A10 works - however it depends how the device connected to this output response to the SPDIF "Error" flag bit which is set to resolve the ESS Left channel locking bug. Most device ignore the error flag (work ok) - while some will Mute.
Why are you conecting the MDAC's digital output to a second DAC?
Why are you conecting the MDAC's digital output to a second DAC?
davidjt
pfm Member
MDAC Problem....or not?
Downloaded 3 albums from Linn Records last night: 2 x FLAC 24/192 and one ALAC (bought when using a Macbook). Playing from a Windows PC (using JRiver) this morning, the ALAC plays fine, automatically converted to m4a, whereas the two FLAC albums (converting automatiacally to 24/96 to suit the MDAC) both repeatedly jump from half-way through one (long) track to the next. Does anyone know whether this is likely to be an MDAC, a JRiver or a Linn issue? Many thanks.
Downloaded 3 albums from Linn Records last night: 2 x FLAC 24/192 and one ALAC (bought when using a Macbook). Playing from a Windows PC (using JRiver) this morning, the ALAC plays fine, automatically converted to m4a, whereas the two FLAC albums (converting automatiacally to 24/96 to suit the MDAC) both repeatedly jump from half-way through one (long) track to the next. Does anyone know whether this is likely to be an MDAC, a JRiver or a Linn issue? Many thanks.
JohnW
pfm member
https://dl.dropboxusercontent.com/u/86116171/MDAC2 -60dB 132dBA DNR.jpg
Above is an FFT of the MDAC2's analogue stage attached to JariP
Salvaged MDAC
Dynamic range 132.5dBA (Balanced) and THD 0.000087% 1KHz 0dB!
This Dynamic range result is close to my all time personal best - I believe the MDAC2 will have the highest Dynamic range performance in the industry (it will improve by a few more dB on the final PCB)...
There is a chance that the THD results will improve further once I have the complete design... although 0.000087% its amongst the very best already.
With the VFET AMPs, I'd really like to include internal gain scaling to maximise the dynamic range offered by the MDAC2 - the Tube noise looked good at about -120dB... (Which is good for a tube)...
Above is an FFT of the MDAC2's analogue stage attached to JariP
Salvaged MDAC Dynamic range 132.5dBA (Balanced) and THD 0.000087% 1KHz 0dB!
This Dynamic range result is close to my all time personal best - I believe the MDAC2 will have the highest Dynamic range performance in the industry (it will improve by a few more dB on the final PCB)...
There is a chance that the THD results will improve further once I have the complete design... although 0.000087% its amongst the very best already.
With the VFET AMPs, I'd really like to include internal gain scaling to maximise the dynamic range offered by the MDAC2 - the Tube noise looked good at about -120dB... (Which is good for a tube)...
iansr
pfm Member
https://dl.dropboxusercontent.com/u/86116171/MDAC2 -60dB 132dBA DNR.jpg
Above is an FFT of the MDAC2's analogue stage attached to JariP
Dynamic range 132.5dBA (Balanced) and THD 0.000087% 1KHz 0dB!
This Dynamic range result is close to my all time personal best - I believe the MDAC2 will have the highest Dynamic range performance in the industry (it will improve by a few more dB on the final PCB)...
There is a chance that the THD results will improve further once I have the complete design... although 0.000087% its amongst the very best already.
With the VFET AMPs, I'd really like to include internal gain scaling to maximise the dynamic range offered by the MDAC2 - the Tube noise looked good at about -120dB... (Which is good for a tube)...
Awesome John
I'd encourage you to do the gain scaling on the amps. In fact I'd say do everything you can to optimize the SQ.
https://dl.dropboxusercontent.com/u/86116171/MDAC2 -60dB 132dBA DNR.jpg
Above is an FFT of the MDAC2's analogue stage attached to JariP
Dynamic range 132.5dBA (Balanced) and THD 0.000087% 1KHz 0dB!
This Dynamic range result is close to my all time personal best - I believe the MDAC2 will have the highest Dynamic range performance in the industry (it will improve by a few more dB on the final PCB)...
There is a chance that the THD results will improve further once I have the complete design... although 0.000087% its amongst the very best already.
With the VFET AMPs, I'd really like to include internal gain scaling to maximise the dynamic range offered by the MDAC2 - the Tube noise looked good at about -120dB... (Which is good for a tube)...
Hi John,
Very promising results! Can't wait for it
Please,
once you wrote: "THD is limited by the ESS DAC operated in voltage mode - so no change in THD as the ESS DAC is the limitation not the Analogue stages themselves (XLR 0.0008% THD).
I know 2 ESS DACs in dual mono are going to be used, but I guess limitation remains or is only slightly changed?
Just wondering.....
Cheers,
Jan
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