advertisement


MDAC First Listen (part 00101111)

Status
Not open for further replies.
misterdog said:
We already have this, Fusion upgrade Mdac fed with a 5 rail power supply into ESL's.

I call it - Paul.

Though I don't possess a 'Fusion' though I'm sure the Fdac will bring this and more to the table.
Click to expand...

The FDAC is more in the realm of the Dave than the Hugo then?
 
Just opened my MDAC up to have a look at the CN1 connector orientation, mine is also numbered opposite to Johns drawing, I take I ignore the connectors numbering and wire as per Johns diagram.

Also spotted I have more bulging caps, John changed a bunch when it was last with him, they are small 470uf 6.3v Lelon and about 9 need replacing, what are you guys using to replace them?

I found these Rubycon http://uk.rs-online.com/web/p/aluminium-capacitors/7037453/
 
Yes ignore the numbers on the connector.

I have lots of bulging caps too. Hoping it will survive until the FDAC arrives as there is no way I'm going to attempt to replace them.
 
Thanks for the replies. I do have SMT rework experience but that was with nice equipment at work. I have a Weller WSD81 soldering station with a few tips, flux and desolder braid, not sure if I'd get enough heat, I do have another half decent iron too.

I got pretty confused about the original caps as they are marked RXY, but according to this data sheet they don't do them in 6.3v http://www.megastar.com/Content/pdfs/RXY.pdf

I'll order the Rubycons and have a go at some, I know when to stop before damaging anything.
 
Removing them and replacing them is fairly easy (once the holes are cleared)

Clearing residual solder left in the through holes however is a PITA. the inner ground plane prevents enough heat getting through.
 
misterdog said:
Removing them and replacing them is fairly easy (once the holes are cleared)

Clearing residual solder left in the through holes however is a PITA. the inner ground plane prevents enough heat getting through.
Click to expand...

Forgive a possibly stupid question, but thinking laterally would a pin drill be any use?
 
davidjt said:
Forgive a possibly stupid question, but thinking laterally would a pin drill be any use?
Click to expand...

Not a stupid question but not a good idea as the drill will almost certainly remove the plate through between layers effectively bricking the board.
 
JohnW said:
Jem,

I agree as in the Lab I sometimes operate the MDAC on DC power supplies, but always via the MDAC Power input board - I think operating direct bypassing the AC - DC board is the key here.

By editing the original PCB files I can spin a PCB in a couple of hours that allows DC input and keeps the front panel switch ....
Click to expand...

John,
Not so long ago, when somebody asked about the MDAC-2, I wrote
"The MDAC-2 is dead!"
Looks like I was wrong.Isn't this a (Lakewest) MDAC-2, but now with linear power supply? Quite a resurrection!
I guess this could be wired to the 9-pin DIN socket, getting rid of iansr's trailing wire problem; this would allow 3 wires to be used for the higher current D(+) line. However, maybe I'm jumping ahead too much; hope you had time for a beer or two in Munich (yes, I know it's not Czech beer, but...)
 
Bob,

John was talking about the small PSU input PCB. I wouldn't call a PSU swap MDAC-2.
 
fusion5 said:
Bob,

John was talking about the small PSU input PCB. I wouldn't call a PSU swap MDAC-2.
Click to expand...

Perhaps not, but for those of us who have never heard a Fusion or Toy, it's a big step up. The only review of the MDAC+ I've seen so far doesn't exactly go overboard on the improvement in SQ, which suggests that the new internal psu is nothing special.
Apart from the fun and the improvement in SQ, playing with cheap psus has really brought home to me how compromised by the pricing pyramid all our kit really is, and consequently how fortunate we are to be getting something like (or better than?) a Dave for a fraction of the price.
If I wasn't really happy with my current (s/h) speakers, I'd be investigating DIY options right now.
 
Bob L said:
John,
Not so long ago, when somebody asked about the MDAC-2, I wrote
"The MDAC-2 is dead!"
Looks like I was wrong.Isn't this a (Lakewest) MDAC-2, but now with linear power supply? Quite a resurrection!
I guess this could be wired to the 9-pin DIN socket, getting rid of iansr's trailing wire problem; this would allow 3 wires to be used for the higher current D(+) line. However, maybe I'm jumping ahead too much; hope you had time for a beer or two in Munich (yes, I know it's not Czech beer, but...)
Click to expand...

It's that much of a change it could easily be considered MDAC - 2 IMO.
5 Rail PSU + Fusion certainly is.

What we need to know is how much extra a Super Reg PSU adds.

You only end up with one spare wire using the 9 pin DIN.

L channel +/-/0
R channel +/-/0
Digital +/0

=8 wires, the 9th is assigned as extra digital ground or cable shield.
 
davidjt said:
Forgive a possibly stupid question, but thinking laterally would a pin drill be any use?
Click to expand...

Not a stupid question at all - so long as you are VERY careful. We use this method at work to remove solder from heavy ground plane boards. Don't use an electric drill though, we use a small hand held drill holder which you just roll between your fingers, that way you can feel how much friction you are generating and you won't snap the drill bit or do damage. Start with the smallest drill size you have, we use 0.3mm, and slowly work up until the hole is large enough to get the lead on the new component through. I can't remember ever damaging a barrel using this method.

Something like THIS
 
This site contains affiliate links for which pink fish media may be compensated.
misterdog said:
It's that much of a change it could easily be considered MDAC - 2 IMO.
5 Rail PSU + Fusion certainly is.

What we need to know is how much extra a Super Reg PSU adds.

You only end up with one spare wire using the 9 pin DIN.

L channel +/-/0
R channel +/-/0
Digital +/0

=8 wires, the 9th is assigned as extra digital ground or cable shield.
Click to expand...

I was assuming we can use a common ground for L,R and digital. Only the digital ground is carrying current, and using the shield for this should mean higher current capability for this return.

In the excitement, I had misunderstood John's comment about keeping the front panel switch; I guess this happens anyway if the main board is unchanged. Likewise, my comments about wiring are taken care of if the new "PSU board" is just a connector board. Maybe we need to wait for John to get back before making too many assumptions, but I would still hold out for "MDAC-1.5"!
 
davidjt said:
Perhaps not, but for those of us who have never heard a Fusion or Toy, it's a big step up. The only review of the MDAC+ I've seen so far doesn't exactly go overboard on the improvement in SQ, which suggests that the new internal psu is nothing special.
Apart from the fun and the improvement in SQ, playing with cheap psus has really brought home to me how compromised by the pricing pyramid all our kit really is, and consequently how fortunate we are to be getting something like (or better than?) a Dave for a fraction of the price.
If I wasn't really happy with my current (s/h) speakers, I'd be investigating DIY options right now.
Click to expand...
If you are thinking diy for speakers look at the Troels Gravesen website there are some great designs I built the Illumina 66 floorstanders and since then I would not even contemplate buying ready made again.
 
Coll said:
If you are thinking diy for speakers look at the Troels Gravesen website there are some great designs I built the Illumina 66 floorstanders and since then I would not even contemplate buying ready made again.
Click to expand...

Thanks for that: from a brief look, it appears that speaker building could become a separate hobby by itself. :)
As I'm struggling to decorate & furnish a holiday home, and rashly put my name on the VFET list as well as both the others, I may look again in a year or three.
 
Status
Not open for further replies.


advertisement


Back
Top