Midiman Super Dac

Isaac

Was yours the Oscon-filled unit?

Did you do any other mods after the analogue regs, 'cos I reckon it would sound better with WM's choice of Stargets on the analogue supplies, unless you do further mods (details available on request).

Andy.

 

Modding phase 2

My last attempt to post got eaten by my PC, so here's another try.

I've had a closer look at the PSU in the Superdac and it uses two voltage doublers to create +/-18V from the single 9V input (and a seperate half-wave rec to produce the raw feed for the +5V).

The input from the transformer is AC coupled into the doubler, via the two 470u caps next to the DC input socket.

The output caps, which are the input caps for the +/-15V analouge reg's are also 470u, and are the two caps directly to the left of each reg (looking from the front of the DAC).

Raising the value of these (I'm curently using 1000u Panasonics, since they're in my parts bin and fit) reduces the ripple into the reg's and is beneficial. Since we are drawing little current from these supplies (a few mA) lowering the input coupling caps (I've used 220 Rubycon ZA's, same reason as above) seems beenficial, as it reduces the peak currents flowing from the transformer and around the doubler circuit. The raw supply V will drop a little, but not enough to cause problems.

These little mods were quite effective in my case, adding better bass quality and punch to the sound.

Secondly, as mentioned before, I've modified the loop filter components. If you follow pin 20 of the CS8414 you'll find a 1K followed by a 47n capacitor - these two components with the receiver internals form a second-order loop filter for the PLL clock recovery circuit.

In this form they only attenuate jitter above about 10-20kHz, so an attempt to reduce this seemed in order.

Currently I have 0.47u + 200R in place of the existing components. With care you can do this from above, removing the old components and fit the new.

Additionally I changed the loop filter to a 3rd order, to do this you need to add a capacitor directly between pins 20 (loop filter) and pin 21 (AGND). I'm currently using a 6800pF cap here, you may be able to go to 0.1u, but I didn't have a suitable cap in the bin, with long enough legs!.

Soldering this is tricky if you're not into SMD, but can be done with care - double check all soldering afterwards to ensure there are no shorts. I laid the cap on top of the chip and bent the legs down, cropping them to length before soldering.

This latter mod is effective, but in the same way a better clock sounds, i.e. no change to the basic character, but an improvement in the music, tighter punchier bass, more detail, better treble etc.

The unit still locks on to a 44.1 signal well, I've not checked a 96k signal yet, although the previous modified loop filter to this one (not described) locked on fine.

Give the new components a while to run in, the Superdac seems to take about an hour to really come on song, even after a relatively short downtime.

It's sounding rather good now, I'm shocked!

Andy.

 

Still quite impressed by the stock (albeit modded with RCA output) unit. Has definetly improved the sound to the system.

 

Errata

I wrote: -

That should read 0.01u!, I've found one to try and it works.

Andy.

 

Well, some resurrectional surgery was preformed on Wm's superdac this afternoon, we (Iaasc mister small fingers) replaced the dac chip with the later 192khz version, I rejigged the 5v reg, but still no joy, looks like the 8414 is gone the way of all good rock 'n' roll stars, heading toward oblivion at a rapid rate, so we may possibly replace it with the 192khz version 8420, we'll see, then after a good thrashing it's up for sale psu & fancy cable an all Wm

 

This thread has been fascinating. Is there a 192Khz version currently commercially available?

 

Question for Andy W: How does your DVD/SuperDAC combo currently compare with the CD5?

 

Question

Henry,

It's still worse, but remarkably good considering the cost differential, which is vast.

Andy.

 

@Andy

interesting stuff with the CS8414 loop filter. Im shortly recieving a DAC using the CS8414 and PCM1716 dac for which ill start by building a decent offboard PS. Would simply changing the loop to 3rd order work (leaving the rest stock)? Ive read of values as low as 3300 pf elsewhere.

Cheers

 

re: Loop filter

It was difficult to find the relevant data to actually design the loop filter to a target spec, so it was an iterative process based upon data available.

The narrower the loop bandwidth, the more likely it will have problems locking on to very jittery or noisy signals, since we don't want to be feeding in poor signals anyway narrowing it and reducing the lock-in range doesn't seem a disadvantage to me.

I think it's worth trying the values posted to see what you think, if you let me know the existing values, I can offer advice as to capacitor value for a 3rd order response, with hopefully a little less jitter peaking.

The Sigma-delta dac in the superdac should be less suscpetible to jitter, although previous experience shows that the sensitivities are still clearly audible.

For anyone who wants the 'best' solution, you should replace the PLL-recovered clock with a stable oscillator at the DAC and then feed it back to a suitable transport to synchronise it.

This is beyond the scope of my mods to my friends DAC! Next port of call is to drop in some simple discrete regs in place of the +/-15V parts (there's no room for super-regs here).

Andy.

 

Thanks, when i get it ill have a look inside and see what i can find. If a simple cap addition can help then this can only be good Depending on how it sounds i had considered installing it into an exisintg cd player and using i2s instead of spdif.

 

Providing Iaasc manages to accquire another 8414/20, you guys can hear Project super dac, on the MB day, it's a little bit more advanced than the others, but it's easily reachable by most. see what you feel about them. Wm

 

has anyone paired the superdac with an arcam transport.?

Im thinking this might be a cost effective way of improoving and perhaps livening up my trusty alpha 8 CDP.

 

Hmmm, too late, ive just ordered one! i figure i can try hooking it up to my minidisc and even (scorn) my DAB tuner as well as my CD player.

:techno:

 

Balanced outputs

Andy,
One area of comparison that you have not been able to pursue is that of the sound quality using the balanced outputs vs the single ended, and then how that compares to the CD5. I suspect that in the context of my system it would alter the balance one way yet in your naim system the cd5 will always have the edge. As you say it is very impressive the sound quality that can be achieved from what is essentially a dirt cheap unit.
Regards
David

 

hi all re superdac

i must admit i have rather duff hearing in one ear so its a real job for me to notice differances in kit. and to be honest i cannot tell the differance between arcam cd73t fitted with superdac.

someone from another forum came round to demo an item i had for sale yesterday.

he was interested in how superdac compared to my arcam cd73t

we tried toshiba 110e dvd player £120 new with /without superdac

arcam cd73t with /without superdac

the person hearing the superdac thought the best results were arcam cd73t+superdac ,and that the superdac gave at least a 10% improvement.


the dac had only been running a few mins rather than the recomended 45mins warm up

the super dac i have is standard apart from rca mod ,used wall wart socket supplied, belden i/c and using a hk 507 av amp, old pair of mordaunt-short speakers.

used track 1 from naim hi-fi collection disk (new dawn) which is a top notch accoustic recording .

 

Well I generally tend to leave the dac powered up 24/7 and noticed an improvement over the stock sound of the 63 marantz Ki sig. This is with a standard wall wart plug as well. Oh and I also have slightly duff hearing in one ear as well.

Certainly been one of the more positive upgrades made to the system

 

Well project SD is alive and rockin' again, Iaasc managed to accquire the neccessary chip, after a spot of careful replacement jobs a good un, sounding damn fine again also.

 

An excellent thread.

Email Group M-Audio SuperDAC 2496 has been been opened.
There must be thousands of users of this excellent DAC around the world.

Many thanks to Tony for giving permission to use his pics and mods to get it going.

Please feel free to post messages, info on modifications, tweaks, ideas, pictures and files.
Any information you have on this DAC or related to it will be greatly appreciated.

To visit the group on the web, go to:
http://groups.yahoo.com/group/M-Audio_SuperDAC_2496

Group Email Addresses:
To post message: [email protected]
To subscribe: [email protected]
To unsubscribe: [email protected]
List owner: [email protected]

 

Has anyone tried a Diecast Box using aluminium alloy?
It will provide a fully screened enclosure.
Maplins LH74R, £13 is the same size as the ABS box Tony used.

Is it still possible to drill holes using hand-held tools?
Any special insulation material required under the tranny?

Thanks.