Thanks for that - I'll ask again later in your design phase what the ideal voltages and current capacity needs to be to support a potential L2 + L4 combo.
MDAC First Listen (part 00100001)
- Thread starter stellablues
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Thanks for that - I'll ask again later in your design phase what the ideal voltages and current capacity needs to be to support a potential L2 + L4 combo.
Richard Kimber
pfm Member
Back to the MDAC2
Does anyone see input voltages lower then 15.2V?
+15.8 on my Premium Fusion. This gets its power from an Isotek Sigmas.
- Richard
JohnW
pfm member
Hmm, thats on the low side - I'll have to modify a PSU for your MDAC2, Please remind me when we are in the process of shipping your unit.
You should mention the low voltage to your electricity provider... ATM, you are waiting longer for your tea to boil
Hmm, thats on the low side - I'll have to modify a PSU for your MDAC2, Please remind me when we are in the process of shipping your unit.
You should mention the low voltage to your electricity provider... ATM, you are waiting longer for your tea to boil
I am using UK version of the transformer/power supply. Could that explain this difference? If it is tuned for 240 VAC in mind? We have 230 VAC in finland. I have a power regulator which tells if VAC levels deviate too much from standard. According to it the mains VAC is withing range. MDAC is not connected to that unit at the moment tho.
ps. The reason for UK power supply and MDAC is that back when i ordered MDAC it was near impossible to get one from Finland. However, ordering from UK did not help at all, since MDACs were sold out everywhere back then. But thats another story.
davidjt
pfm Member
Temperature issue (Part 2)
Having been on all day yesterday, my MDAC suddenly began 'clipping' and was almost too hot to touch. Switched on this morning and everything was back to normal, but still hotter than I'd like.
As MDAC2 will run straight into the main amp(s) it seemed a good time to take my Roksan pre-amp out of the chain, shuffle units for best ventilation and sample XLR MDAC to amp connections. No great difference in SQ (maybe a slightly 'cleaner' presentation, but levels won't have been constant so hard to be sure). BUT with the MDAC's built-in pre-amp now switched on, the case is barely warm. Baffled.
Having been on all day yesterday, my MDAC suddenly began 'clipping' and was almost too hot to touch. Switched on this morning and everything was back to normal, but still hotter than I'd like.
As MDAC2 will run straight into the main amp(s) it seemed a good time to take my Roksan pre-amp out of the chain, shuffle units for best ventilation and sample XLR MDAC to amp connections. No great difference in SQ (maybe a slightly 'cleaner' presentation, but levels won't have been constant so hard to be sure). BUT with the MDAC's built-in pre-amp now switched on, the case is barely warm. Baffled.
Same voltages. +14.9V. There has been lightning storms in the region lately, i'll check the voltages later in autumn. Today was a lightning storm as well. Tens of thousands people without electricity, etc. Temperature has been close to 30c here past weeks, which creates such anomalies. However the regulator should say something if VAC levels change too much. I'll test it later anyways.
Hi John,
RAW MDAC supply voltages in Chorley, UK.
Lowest seen over 24 hours:
Unmodified unit 18.0v
TOY unit 17.0v
Highest seen over 24 hours (at 01:00 local):
Unmodified unit 18.3v - (is that a record?)
TOY unit 17.4v
Yes, I availed myself of an ex-display donor unit. I couldn't let that work you did, slaving through the night, go to scrap.
RAW MDAC supply voltages in Chorley, UK.
Lowest seen over 24 hours:
Unmodified unit 18.0v
TOY unit 17.0v
Highest seen over 24 hours (at 01:00 local):
Unmodified unit 18.3v - (is that a record?)
TOY unit 17.4v
Yes, I availed myself of an ex-display donor unit. I couldn't let that work you did, slaving through the night, go to scrap.
JohnW
pfm member
I've just ordered an extra 30 pairs of VFETs (with the 15 pairs already on there way over) this means I'll have 45 pairs of VFETs in stock.
I'll ship a spare pair of VFETs with each amp (+ spare tube), that means I can build 10 pairs of VFET Monoblocks (excluding my own personal amps) - I just pray I don't blow any amps while developing and manufacturing them!
I'll ship a spare pair of VFETs with each amp (+ spare tube), that means I can build 10 pairs of VFET Monoblocks (excluding my own personal amps) - I just pray I don't blow any amps while developing and manufacturing them!
davidjt
pfm Member
John,
The Roksan is all RCA, whereas the Meridian has switchable XLR & RCA inputs: tried 'converters' between MDAC and Roksan but ditched them. So for some reason taking the output of the MDAC via RCAs was causing stress and via XLRs it's happy as Larry. Which I guess leaves an internal wiring issue or maybe a dodgy interconnect? (I'll check the latter on a meter tomorrow.) Odd that there was nothing wrong with the sound until the MDAC got really hot.
On the bright side, new boards very soon, and XLRs are definitely growing on me.
JohnW
pfm member
Roger,
Good to hear from you
18.3V, Yep that's going to be the UK on the "high side"... Good for MDAC2
Now you have two units have you compared the SQ between them?
JohnW
pfm member
I prefer V0.90 (but it lacks features + and has a few small bugs).
Others prefer A08... it depends upon the SQ balance of you system.
The V0.99 shipped with the MDAC is the worst sounding IMO.
I'm not sure where the Software links are posted now - I've just been to the Wiki and I'm not sure whats going on as I cannot see the links - have they been removed by someone?
http://mdac.referata.com/wiki/Main_Page
According to the IP 202.191.157.38 someone from Mumbai, India on August 3 has deleted the software links and firmware update info - does anyone know how to roll-back the "modifications" to the Wiki?
JohnW
pfm member
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