Micromega Microdac.

[freddypipsqueek]

A few years back I bought a Micromega Microdac – a DAC I had wanted as a kid and which I thne found worked well with my Chiarra. Recently it has lost its way and on finding the following website I decided to recap to see if that would bring it back to life - www.flickr.com/photos/sshobby/sets/72157625914167116/. There was nothing to loose.

The site summarized the changes as follows,

“An old, cute, Micromega Microdac. I found it after I sold the matching MicroDrive, which is a bummer. It sounded OK only, in contrast to the reviews it had received in the 90s, so I decided to see what modern parts could do to it. I upgraded the opamps to OPA604, the diodes to UF4007, the voltage regulators to low-drops out units, and the caps to Nichicon low ESR audio quality caps. The main caps were also bumped up to 2200uf from 1000uf, and they got bypass caps as well. What a difference - it sounds terrific.”

I did all of the above except for changing the voltage regulators. I couldn;t easily work out was a good replecement would be.

I got in a mess with the caps – the 2200uf were bigger and needed to be bent over. The 47uf jobbys were too big so i added some extra 22up to the originals (underneath) and didn’t fit the 47uf ones. The biggest change (I think) was the new diodes replacing the original rectifiers – I'm not sure about this though. When I added new fast recovery diodes to my Cyrus amp I notcied they help as well with the speed and attack.





Finally I did upgrade the op amps from the original TL071CP to the OPA604 and found it much better. I have however now added some Burson solid state jobbies – the red things – and I’m waiting to see how these burn in. I mention this because of the Orange op amp thread currently on the go. If the Bursons don't match well I will go back to the OPA604 which are much more of a cost effectively given the value of the DAC (they seem to worth about 80 or 90 quid). My understanding is that the Orange units are only available as doubles and I already had these single ones.

I would never have tried all of this 2 or 3 years ago. Much is down to the reading what people have done on this site and getting confident - my thanks to all for that.

[freddypipsqueek]

A short update. The Micromega is warming up nicely. I would say a couple things however. Firstly three is a mains induced hum from the digital in connector. I am sure this is due to the mains transformer. This would not normally be an issue but the Microdac takes its digital signal from the coax out of an (ARCAM) irdac and this then hums - disconect the digital out and the hums gone. All has been fixed by a Theta TLC between the two; this reclocks the digital line . . blah blah. The irdac is a nice bit of kit – multiple inputs for digital sources and then the digital out (which also does the USB & ipod connector) so that headphones can be run off the irdac and the amplifier to take the feed from the Microdac.

The second point is that the Bursons seem to add very little. The dac is now in the shelf and will remain as it is – if I take it out I will switch back to the OPA604s and this will happen if the Bursons find another home – Mike let me know if you want to try them but they are single units so may not work in your comparator setup without an adaptor. The Micromega is not good enough to swap for the irdac and this was bit disappointing though I will try this again in a weeks time.

[PinkFloyd]

Great work there mate, good to see I've been up to my eyeballs with all sorts of stuff and not really able to spend time posting here..... I feel really bad about "not yet" following up on the Orange discrete opamp but so many things have happened all at once with me (as is usually the case with most people) and I just don't have the time, at this present period in time, to get down and dirty with the Orange Discrete Opamp.

Remind me of your details / address and I will send one of them to you in the next post..... that way, you can get the evaluation ball rolling and (hopefully) I will be in a position / want to to dedicate my full concentration / passion once you have gone in with your initial evaluation.

PM or email me your shipping address Pip and I will get one in the post tomorrow for you.

All the best,

Mike.

[freddypipsqueek]

Mike. PM sent. I will need a little time to try the Orange Op Amp but I'm more than happy to post first. A.