MDAC First Listen (part 00110000)

[JohnW]

Well its better to add the extra smoothing on the MDAC side - rather then local on the PSU's.

When I have time I'm going to give the Calexs a listen now that the PSU's / System has a few days to run in... If the sound stage is still collapsed and dull HF then I'll try the extra Caps.

 

[fusion5]

Well its better to add the extra smoothing on the MDAC side - rather then local on the PSU's.

Even if the location in the MDAC would be best. Any benefit from adding a rather insane amount of extra smoothing right on the other cable end? Let's assume something like 8x2200uF per rail for the moment

I would prefer not to mess around in the MDAC

 

[JohnW]

Not much benefit, as the PSU interconnect cable impedance undoes all the Caps. good work - also the Calexs Regulator circuit might go unstable with the added capacitance.

I'll try here, if it improves my situation then we can quickly spin a PCB within a couple of hours for DIY build

 

[fusion5]

OK, I'll wait for your findings. Although I don't use the Calex units, I'll check with my PSU supplier about the possibility of adding extra capacitance.

At which cable lengths does this become an issue? I think I need about 60-70cm when using the original power connector hole. I could cut this down to 30-40cm with new holes above the digital coax connectors.

 

[MartinC246]

I am only using my MDAC for CD playback. I didn’t want the CD drive on the FDAC, but I’m now happy to accept it if it helps to standardise the case and particularly after the latest front panel rendering.

After all the recent discussions about improving power supply to MDAC, will the FDAC’s PS be of sufficient quality that we won’t be having similar discussions in future about upgrading the FDAC’s supply? I want to pay whatever it takes for the best now, within limits, but the limits are quite flexible.

Posts a while ago about internal SSD brought a few questions to mind –

Will ripping to and reading from internal SSD need L3? I’m currently paid up for L2.
Will FDAC support an external SSD that needs power from the USB connection?
Given that external SSD doesn’t involve a PC to foul up the output (I assume this is right), will the Regen help (or will it be needed) for external SSD?

Thanks for any help anyone.

Martin

 

[paulski]

I am only using my MDAC for CD playback. I didn’t want the CD drive on the FDAC, but I’m now happy to accept it if it helps to standardise the case and particularly after the latest front panel rendering.

If you're using an external CD player as a digital source for the MDAC it's likely that CD replay via the internal drive in the FDAC may surpass feeding it from your existing player. And, it's one less box. What's not to like?

After all the recent discussions about improving power supply to MDAC, will the FDAC’s PS be of sufficient quality that we won’t be having similar discussions in future about upgrading the FDAC’s supply? I want to pay whatever it takes for the best now, within limits, but the limits are quite flexible.

Agreed although I'm sure John will ensure the FDAC is not compromised by its PSU, especially following the recent improvements folk have found to be possible with a fairly simple PSU upgrade to the MDAC. With that said there always has to be some constraints be they cost, size etc. so it's still conceivable that one day someone will build an outboard supply that may provide some improvement. I suspect the FDAC will be good enough that no one will feel the need to try. At least for a good while anyway!

 

[MartinC246]

Paulski

Thank you for your reply. It will be interesting to hear what John thinks of the MDAC PS upgrade that others have been so impressed by. It does show how we need to let electronics burn in before we can properly assess it. All of my mains cables and interconnects came from Russ Andrews Accessories. He always recommends burning in for 3 weeks. I find that the cables are still improving after 6 weeks.

I am not really opposed to having a CD mechanism, just that it's a slot loader. OK for ripping (hence my other questions) but concerned about using it continuously for CD replay. I'm thinking of sticky fingers (mine) and accumulation of small scratches over many replays.

Thanks again
Martin

 

[russel]

Well its better to add the extra smoothing on the MDAC side - rather then local on the PSU's.

When I have time I'm going to give the Calexs a listen now that the PSU's / System has a few days to run in... If the sound stage is still collapsed and dull HF then I'll try the extra Caps.

Hi John, do you isolate the analogue supply with an inductor?

 

[misterdog]

I'm thinking of sticky fingers (mine) and accumulation of small scratches over many replays.

How would you handle vinyl ?

The trouble is we now see media as 'disposable' and of little value. The installation discs we get tend to only be used once so it matters not if we stick a thumb print in it.

When I was a lad I had to learn how to handle vinyl with the utmost reverence.

 

[davidjt]

And eat gravel?

 

[iansr]

Aye lad it's grim up North.

Have you seen The Trip?

 

[jamjar784]

We used to dream of gravel for special occasions ...

Tried out my Calex PSU's yesterday briefly after 36 hours burn in. No smoke - phew! Definitely no collapsed sound stage and some SQ improvement.

I wonder how much of the reported improvement is due to running the MDAC out of its case? Mine has been in a wooden box (like misterdog) for a while.

Anyway need to get on with fixing the JST connector - 1 fn pin blocked with solder Might have to do a complete replacement as getting the pins out seems impossible. Then I can get a good listen and complete the burn in

 

[JohnW]

Looking forward to it John. Here's a random thought. The spec of the FDAC includes a high quality PSU. If that is going to be on a discrete PCB, would it be feasible to use the same board to construct an external PSU for the MDAC ( for those who will have a continuing need for an MDAC), or are the FDAC's PS requirements just too different?

Ian,

The FDAC has a "Class A" Shunt PSU for each critical section. Basically it consists of a high quality Constant Current Source (CCS) and an Active "Sink" element to maintain the required voltage.

The advantage of a Shunt type PSU is natively high "Line noise rejection" even at High Frequency's and due to the constant current operation (hence the description of Class A) "native" isolation between stages. Its a very different PSU architecture to the MDAC and made possible by the Milled Chassis which can be used as an effective heatsink to radiate the heat of the multiple ClassA PSU's.

Shunt PSU's can also be much faster then conventional PSU topologies.

 

[JohnW]

Exactly, though there may be something buried within this Mini-DSP module once (If) I can get my head around it.

There is a dynamic range compressor/limiter, though no instructions on how to use it

Arh - "dynamic range compressor/limiter" does not sound like the solution, rather a simple "remote" level control is all that is required, maybe with 2 or 3 recallable settings...

 

[JohnW]

John, with this is mind is it worth adding an extra smoothing cap to each rail before it goes to the MDAC?

On the MDAC itself yes - I'm going to see if the AC/DC PSU can be modified to allow this.... easyer for me here in the Lab, but maybe too much SMD rework for others, and then no simple way to return the MDAC to its former self.

 

[JohnW]

I am only using my MDAC for CD playback. I didn’t want the CD drive on the FDAC, but I’m now happy to accept it if it helps to standardise the case and particularly after the latest front panel rendering.

Thanks for the understanding - I expect the CD/DVD to add less then GBP20.

After all the recent discussions about improving power supply to MDAC, will the FDAC’s PS be of sufficient quality that we won’t be having similar discussions in future about upgrading the FDAC’s supply? I want to pay whatever it takes for the best now, within limits, but the limits are quite flexible.

One of the "BIG" advantages of going to the FWC is the internal HQ PSU - I've just posted on the FDAC's PSU topology a little to Ian's question

Posts a while ago about internal SSD brought a few questions to mind –

Will ripping to and reading from internal SSD need L3? I’m currently paid up for L2.

L2 / L3 will both support internal SSD "BUT" you must order the extra internal screening option (as Amongst other reasons the SSD driver is mounted on the internal screening) and install the SSD driver yourself (via an external assessable cover on the FDAC base).

Will FDAC support an external SSD that needs power from the USB connection?

No as the FDAC USB ports are current limited to 500mA each due to internal PSU limitations) as the Quad core ARM requires significant power.

Given that external SSD doesn't involve a PC to foul up the output (I assume this is right), will the Regen help (or will it be needed) for external SSD?

No need for ReGen with internal SSD playback ReGen is only required on the connection between FDAC and USB Host device (Such as the PC).

 

[JohnW]

Hi John, do you isolate the analogue supply with an inductor?

No Inductors are used on the MDAC analogue stage PSU - however inductors are used on the FDAC's Shunt PSU CCS to extend the HF Noise isolation above say 50MHz.

 

[JohnW]

Aye lad it's grim up North.

Its gets better as you approach dear Scotland

 

[misterdog]

Arh - "dynamic range compressor/limiter" does not sound like the solution, rather a simple "remote" level control is all that is required, maybe with 2 or 3 recallable settings...

Yes I have found that by default the Mini DSP has the compressor enabled, sounding better since disabling it.

There are 4 settings in the memory of the DSP module so remote level control is possible

 

[JohnW]

Looking forward to it John.

When you visit bring some of you music on a flash drive - upto 96KHz, so you have tracks you know when we listen here....