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MDAC First Listen (part 00110000)

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JohnW said:
Well I just listened to RTRT Toy MDAC with external and internal Detox with triple Calex PSU's and first impressions:-

1. Bass is now much deeper and firmer - almost to being too bass heavy (I've not adjusted the Sub woofer to keep listening conditions the same).

2. I find myself listening at -19dB to -20dB where I used to listen at -23dB to -20dB

3. Sound now just comes from the speakers :( - with little Left to Right Sound stage

4. The "open" treble is now closed in, and with little macro detail - I guess what Steve Toy would call texture... its now just all about the Bass.

Maybe I need to let the PSU's run in - I could swear that the soundstage opened up more about 30 minutes into listening... I know the MDAC is bad for this, it really needs a warm-up period from cold.

I'm not happy that the MDAC is so sensitive to PSU - and really wonder where my detail and treble have gone :( I'll let the system warm up over night...
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Give it a minimum of 2 to 3 days to come 'on song'. Mine sounded dire at first, so much so I thought I'd cocked up the capacitor replacements I'd also done.
 
paulski said:
Give it a minimum of 2 to 3 days to come 'on song'. Mine sounded dire at first, so much so I thought I'd cocked up the capacitor replacements I'd also done.
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My L3 Toy needs a day to come fully back on song after being powered down anyway.

If you start becoming aware of, say, low frequency at the expense of midrange there is likely to be a timing problem, I would think.

This may resolve itself with warm up - or not.
 
I didn't do extensive listening at first with the Calexes as I'd also replaced loads of caps in the MDAC so was expecting to have to let those settle in as well. That said I did listen at first power up (via MacBook / USB) to verify it was working and was pretty underwhelmed. It seemed significantly 'constrained' both dynamically and in terms of imaging / depth. It wasn't awful but it was definitely worse than a standard MDAC.

Once I'd satisfied myself that the heat the Calexes were generating was to be expected I left it on for several days with internet radio over the digital input but without listening other than at background levels occasionally.

After about 5 days I tried (again it with MacBook over USB) and it was transformed. Massive sound stage and no dynamic issues were immediately clear as were improvements across the board. I didn't notice any downsides although my listening was curtained by the arrival of a turntable upgrade which has meant the MDAC was displaced for now. I tend to listen at varying levels so I can't really comment on whether there's any changed in perceived volume. Could the slightly lower voltage from the Calex be a cause? Presumably not as I guess the local regs drop that anyway.
 
Differing input voltage does not equal different output volume, neither does it affect 'timing' whatever that may mean.
 
sq225917 said:
How do you expect to be able to make a comparison at different volume levels.
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At my "normal" levels the sound is so constrained and "quite" - I'm reserving any judgement until the units run in - if it does come on form then I'd be massively surprised at the difference in sound quality!

At lower levels there is just no Left / Right sound stage or treble :( just Bass Bass Bass - its like someone's installed a Bose system

Maybe there's something wrong with my system (or maybe the terrible sound of the systems at Munich has made me go deaf) - unfortunately I had to solder the PSU cable to the underside of the MDAC PCB so its not easy to do perform a direct A/B comparison between the original and Calex PSU's - I'll try and find a 10W JST Cable today to enable A/B change over.
 
Russel,

All Grounds on CN2 on the MDAC mainboard are connected together - but as 2 & 5 are located next to the Analogue power pins they are the most convenient Ground returns for the Analogue supplies.
 
sq225917 said:
neither does it affect 'timing' whatever that may mean.
Click to expand...

I've always taken "timing" to mean foot tapping abilities... During listening test I discretely observe others to see if they are tapping there feet to the music - a good sign :)
 
paulski said:
I didn't do extensive listening at first with the Calexes as I'd also replaced loads of caps in the MDAC so was expecting to have to let those settle in as well. That said I did listen at first power up (via MacBook / USB) to verify it was working and was pretty underwhelmed. It seemed significantly 'constrained' both dynamically and in terms of imaging / depth. It wasn't awful but it was definitely worse than a standard MDAC.

Once I'd satisfied myself that the heat the Calexes were generating was to be expected I left it on for several days with internet radio over the digital input but without listening other than at background levels occasionally.

After about 5 days I tried (again it with MacBook over USB) and it was transformed. Massive sound stage and no dynamic issues were immediately clear as were improvements across the board. I didn't notice any downsides although my listening was curtained by the arrival of a turntable upgrade which has meant the MDAC was displaced for now. I tend to listen at varying levels so I can't really comment on whether there's any changed in perceived volume. Could the slightly lower voltage from the Calex be a cause? Presumably not as I guess the local regs drop that anyway.
Click to expand...

Yes - I normal forewarn MDAC owners when I replace the caps that it will take a few days for the unit will come onto form - but normally with new caps they sound "hard / cold / bright", not Bass heavy with no detail.
 
JohnW said:
I've always taken "timing" to mean foot tapping abilities... During listening test I discretely observe others to see if they are tapping there feet to the music - a good sign :)
Click to expand...

I think you can tell by looking at your own feet...😎
 
paulski said:
I might try similar, two per Calex right? I did open one of the Calexes before I installed them and they had 1000uF for soothing duties if I recall.
Click to expand...

Correct on both, technically you only need one Cap for the Digital + supply.
 
Oddly, although the link is to a 50VW cap, the illustration shows a 16VW, 'for illustrative purposes only' which could confuse the issue. Confused me, briefly, anyway.
 
IIRC my PSU will have 4400uF per rail. I think that should suffice.

I even got 8800uF for the "power hungry" digital section, since I'll wire two rails in parrallel.
 
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