I was waiting on the case before I updated this thread, there has been setback after setback with that but finally I think it's going to be ready soon. A few things have happened since I last checked in.
First:
Quote:
Originally Posted by peranders
Since you for a while at least (still I'll hope) has got your Super Regulator working, what's your impressions so far?
|
Right.. The super regulator is still working so far, I found that the ths4601 opamp seems to be an improvement noise wise for the amp over the ad825. I also tried swapping in the ad797 but it didn't like the capacitive load even with a pair of diodes on the inputs.
I have a ferrite bead over the power cables going out of the jung regulator, to the m3, and have increased capacitance after the regulator (so there's 3000uF straight after the jung, and 3000uF on the amp board) this seems to have helped everything, however bass slam is still marginally less than with the other "cheaper" power supply.
There is still some hiss at high volume which could be source related. I haven't had a whole lot of time to play with different sources yet.
The output wires from the jung are very very sensitive to RF (especially AC hum), I might have to shield the AC wires.
The heatsinks on the jung regulator get pretty hot but the devices are within spec.
Second:
I've removed the C2 capacitors on the m3, and stuck with the ths4631 opamp. Removing the capacitors has seemed to make a very large difference in soundstage, vastly opening it up. Detail has also improved with the ths chips which before seemed very compressed and a bit grainy - while this could be due to burn in, I think it's more an effect of the caps.
I've biased the mosfets to 125mA and am running 25v through the m3. While I have been tempted to increase this I haven't needed to so there hasn't been any motivation to do so. If it ain't broke, don't fix it.
I've found a slight anomaly with the AD8610 opamps, when driven hard (over half volume/gain 11) the treble becomes uncontrolled and peaky, but lower down it is fine. Covenant found the same problem with his mint (ad8620) so I'm guessing it is something to do with having them buffered or perhaps class A bias.
The case for the M3 is due tomorrow night.. I'm going to burn the midnight oil to try and get the amp ready for the meet in sydney on the weekend. Case pictures and final pictures will be forthcoming...
Dakiller heard the amp on the weekend and his first remark was "very very detailed" - so I must have done something right. I've compared to his ppa (which also uses a protoboarded jung and has opa627 opamps) and I prefer the M3 by a large margin.
I have another transformer coming from digikey, one that isn't so big, but I doubt it will be here in time for the meet.
that is all for now... here's a pic of the amp as it is, with the exception that the opamps have been changed to the ths4631s, and the opamp on the jung is now a ths4601:
Jaz out (note more up to date pictures are coming..)