Mods for Harman/Kardon HD970

Status
Not open for further replies.
Hi - I just bought one a week ago:

Initial listening results are a dissapointment: dull and poor dynamics - Little depth and not very engaging - although detailed.

My 'old' machine is a modified Marantz CD 63 with AD 826AN Op-Amps - Chosen for their clarity, depth, dynamics etc.. Fantastic amps as long as they are properly bypassed on the supply lines as they are fast!. Cant detect oscillation upto 25Mhz (my 'scope limit)

I compared them with BB OPA 2604 and OPA 2134 neither of which I liked:

The OPA 2604 colored the sound and was overly "bassey" - the OPA2134 was tiring to listen to.

I have built Elliot pre amp / phono pre-amp and Linkweitz-Reily 3 way electronic crossovers with AD 826AN and they sound fantastic.

OK - I should have read the service manual for HD 970 First - but it does have some interesting elements - e.g. the I/P select to use the DAC. I think that with AD 826AN - op-amps replacing maybe all the BurrBrown offerings it might do the trick. As I have binned all the original packaging I am commited to get the thing to sound good.

Watch this space. The rest of my system is fully tri amped using ESP P3A power amps (3 amps per mono-bloc) / channel and sounds fantastic - nice one Rod!
 
I have replaced all elcaps with Black Gate FK, NX, and PK. Hard to remove the big PSU caps since they are glued! I also placed a lot of vibration dampening inside. After the usual BlackGate burn-in-time (50+ hours) there is a clear improvement with more attack in transients and a more open soundstage. The bass is also tighter. I am now contemplating changing the OPA2134s to either AD8620 or THS4032. The supply is 12V according to the service manual, but I don't know the gain (THS4032 needs minimum Gain=2).
 
Status
Not open for further replies.