misterdog
Not the canine kind
Easy to include holes in the top of a plywood case if headroom is an issue.
MDAC First Listen (part XXIX)
- Thread starter Asphaltradler
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Easy to include holes in the top of a plywood case if headroom is an issue.
zzzmonster
pfm Member
Yes, it simplifies things to reuse the existing chassis, but if you keep thinking about further upgrade, I think the chassis size is going to hold things back.
Possible Upgrade options
1. Extra FPGA board
2. Tube and tube board
3. Future digital interfaces
There aren't space
That is why I am still on the fence.
JohnW
pfm member
Yes, it simplifies things to reuse the existing chassis, but if you keep thinking about further upgrade, I think the chassis size is going to hold things back.
Possible Upgrade options
1. Extra FPGA board
2. Tube and tube board
3. Future digital interfaces
There aren't space
That is why I am still on the fence.
It makes sense that 1 & 3 will be on the same PCB that will be mounted upside down and above the Mainboard.
The Tube poses more an issue due to PSU requirements (not so much an issue of space).... maybe the Tube versions (if it happens) will require a different external PSU... Just concepts at the moment - waiting for final judgement on testing the development PCB's...
JohnW
pfm member
Jiri,
Yes the Analogue / Digital Analogue sections will be on the mainboard (ESS DAC's, Clock etc).
It might offer a slight advantage to having the USB physically "isolated" on the second PCB with the more "nasty" digital processing - but the problem is however that even a few pF of capacitance will couple RF energy into the the audio sections... Capacitative coupling from the underside of the PCB into the chassis etc, for any decent amount of RF isolation the isolation barrier must be external to the MDAC2 chassis.
I'm considering the possibility of an option for USB galvanic isolation, but it would offer little in the way of RF isolation at higher frequency's - this would breakup the PC / Audio system ground loop - but little else...
Yes the Analogue / Digital Analogue sections will be on the mainboard (ESS DAC's, Clock etc).
It might offer a slight advantage to having the USB physically "isolated" on the second PCB with the more "nasty" digital processing - but the problem is however that even a few pF of capacitance will couple RF energy into the the audio sections... Capacitative coupling from the underside of the PCB into the chassis etc, for any decent amount of RF isolation the isolation barrier must be external to the MDAC2 chassis.
I'm considering the possibility of an option for USB galvanic isolation, but it would offer little in the way of RF isolation at higher frequency's - this would breakup the PC / Audio system ground loop - but little else...
fred sonnen
pfm Member
hallo John
Many month ago we discussed the opportunity to integrate a analogue input in the mdac2. Your idea was to make that with an adon card. Is this still in your mind?
If you still want to use the mdac case and separate the digi-input in a adon card you probably didn't have enough space for a second adon card...
regards
f.s.
Many month ago we discussed the opportunity to integrate a analogue input in the mdac2. Your idea was to make that with an adon card. Is this still in your mind?
If you still want to use the mdac case and separate the digi-input in a adon card you probably didn't have enough space for a second adon card...
regards
f.s.
JohnW
pfm member
Hi Fred,
Are you referring to the AV bypass (which will be fitted as standard) - or a full Analogue pre-amplifier (or just ADC)?
We will most likely design an external Analogue pre-amplifier using the Areks Stepped attenuator routed via the MDAC2's AV bypass input. The External pre-amplifier will be controlled via the MDAC2's front panel / Remote Control.
We will also include an option for a MM/MC Phono input stage.
You tell me more about a computer that is as cheap, quiet (as in fanless, discless) and small as a Squeezebox Touch. Can't be done.
fred sonnen
pfm Member
thanks for clarification.
No, we discussed about a " real" analogue input. Now you prefer a external solution. Thats OK. Its not as elegant as an all in one box but it makes it lot easier for you ;-)
regards
f.s.
fred sonnen
pfm Member
Hallo
Greater DSP power?
perhaps you have in mind that we discussed the opportunity of LF room correction many month ago ;-)
is this still a issue that you are thinking about?
regards
f.s.
Greater DSP power?
perhaps you have in mind that we discussed the opportunity of LF room correction many month ago ;-)
is this still a issue that you are thinking about?
regards
f.s.
Hi John,
Will your external pre-amp have the ability to simultaneously connect both the AV bypass and also a turntable as can be done with the CDQ, with the ability to swap using a remote? This would be exactly what I need
JohnW
pfm member
JohnW
pfm member
Hi Fred,
No the heavy DSP horsepower would be required for an advanced filter (and possibly modulator) idea I have - if indeed its possible, the maths is beyond me so it would be left to an applied Mathematician and Dominik to develop the filter algorithms.
Julf
Facts are our friends
Raspberry pi?
fred sonnen
pfm Member
Right enough! But you know what my point was. A DAC should just connect directly to your network. You only have to look two posts back for still seemingly unresolved issues with USB. Talking of the Raspberry Pi - seen the Intel Edison?
Absolutely yes please plus one bro.
PhilCTTE
Senior mumbler
Would this perform differently to an Olimex isolator?
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