Ad8599
done both of mine
there is 8 opamp on the board for the xlr section
8op amp underneath as buffer
4 opamp for the RCA output
if you use your 4x10 as a analog receiver(phono or FM tuner)
I would recommend the 2 or 4 analog side opamp
see my website in my signature, I think I have few picture un there
done both of mine
there is 8 opamp on the board for the xlr section
8op amp underneath as buffer
4 opamp for the RCA output
if you use your 4x10 as a analog receiver(phono or FM tuner)
I would recommend the 2 or 4 analog side opamp
see my website in my signature, I think I have few picture un there
An externally hosted image should be here but it was not working when we last tested it.
you mean I should change only red and blue opamp right?
Can you tell why you choose Ad8599?
The NJM2068 op-amps are fine. You certainly can't replace them with anything superior enough to warrant all the hacking required on your pcboard.
As noted by Tom, watch out for device packaging differences if you go down that road.
Dave.
Base on my minidsp 2x4 HD, you might want to the cap tweak first. Try replacing the coupling caps with film if possible using extension wire from solder pad. If not enough space, try replace with the green Nichicon Muse BP. My minidsp has at least 3 coupling cap in signal path. I even tried bypass the opamp and direct output with just a coupling cap, sound is much more smoother but lack some dynamic, will need a good buffer in between. If you minidsp has differential out, you can try a 10k:10K output transformer, you can do google transformer dac out.
Can you tell me which one is coupling caps?
http://diygeezer.com/sites/default/files/inside-minidsp-4x10-hd.jpg
thank you
the capacitor are Nichicon KW (stock) sound lame.
some of them are polarised by DC and some have 0Vdc across
the polarized one, use Panasonic FM
the one with no DC offset, use Bipolar nichicon muse as already mentioned or a piece of wire if you're courageous (I do for the output ones but my amps all have DC servo so do it at your own risk)
Bypass the power supply opamp capacitor too, minidsp only use a small one to bypass +-VCC, way too small, I've added lots of 47Uf/16v to bypass every opamp.... (pana FM in one and Nichocon KA in another one I have)
Thrust me, use Pana FM...
Not fun to do but doable.
some of them are polarised by DC and some have 0Vdc across
the polarized one, use Panasonic FM
the one with no DC offset, use Bipolar nichicon muse as already mentioned or a piece of wire if you're courageous (I do for the output ones but my amps all have DC servo so do it at your own risk)
Bypass the power supply opamp capacitor too, minidsp only use a small one to bypass +-VCC, way too small, I've added lots of 47Uf/16v to bypass every opamp.... (pana FM in one and Nichocon KA in another one I have)
Thrust me, use Pana FM...
Not fun to do but doable.
In your website I saw you remove all off input output capacitor right? is it better ?
Yes, I removed the input and output capacitor on both my 4x10.
if you have no DC offset at the input, It make sense to do so.
2-3mv DC of offset won't change anything.
On the output side, it's more tricky.
I assume the risk as it sound much better but if something goes wrong, you could send straight DC to the amp that may amplify it.
this will domino to huge DC to the speakers. (likely the amp rail voltage)
I use fusible on all my drivers and I've changed them a few times. (once on a power outage, the minidsp send DC for a short period on pwr down and all of the fuses blew...)
No driver was broke and I'm happy that my beryllium tweeter survived.
With no output cap option, you have a start-up and shut down sequence to follow.
Not to be understated.
sonic gain are quite significant.
Tried the nichicon KZ and liked them too but it wasn't in the minidsp so I can't draw solid conclusion for this case. They definitively do something to the midrange and have good attribute. I used them in a SS pwr amplifier.
I shall have done it with the KZ on my 2nd 4x10hd but wanted to try the KA for direct test.
It was painful to hope the KA would improve with burn-in. they didn't or if they did, it wasn't enough... the one with the KA inside sounded much more Dull and uninvolving.
I replaced the KA to the FM and life came back!
Soldering the opamp is a PITA
Yes, they are different size.
I used a spacer to elevate the ad8599 opamp.
then solder tiny piece of wire to join all the contact.
very meticulous job and quite time consuming...
Worth the time and I would do it again in a heartbeat.
Ad8599 are very good (thru, not my favorite dual anymore but still in my "top 5")
Was my favorite dual at the time of the upgrade...
You could use any opamp really, as long as it's a dual.
Later
if you have no DC offset at the input, It make sense to do so.
2-3mv DC of offset won't change anything.
On the output side, it's more tricky.
I assume the risk as it sound much better but if something goes wrong, you could send straight DC to the amp that may amplify it.
this will domino to huge DC to the speakers. (likely the amp rail voltage)
I use fusible on all my drivers and I've changed them a few times. (once on a power outage, the minidsp send DC for a short period on pwr down and all of the fuses blew...)
No driver was broke and I'm happy that my beryllium tweeter survived.
With no output cap option, you have a start-up and shut down sequence to follow.
Not to be understated.
sonic gain are quite significant.
Tried the nichicon KZ and liked them too but it wasn't in the minidsp so I can't draw solid conclusion for this case. They definitively do something to the midrange and have good attribute. I used them in a SS pwr amplifier.
I shall have done it with the KZ on my 2nd 4x10hd but wanted to try the KA for direct test.
It was painful to hope the KA would improve with burn-in. they didn't or if they did, it wasn't enough... the one with the KA inside sounded much more Dull and uninvolving.
I replaced the KA to the FM and life came back!
Soldering the opamp is a PITA
Yes, they are different size.
I used a spacer to elevate the ad8599 opamp.
then solder tiny piece of wire to join all the contact.
very meticulous job and quite time consuming...
Worth the time and I would do it again in a heartbeat.
Ad8599 are very good (thru, not my favorite dual anymore but still in my "top 5")
Was my favorite dual at the time of the upgrade...
You could use any opamp really, as long as it's a dual.
Later
I would make some tweak for 2x4HD
- upgrade 2 clock to better grade
- by bypass onboard opamp and use a external buffer, can you show me a conection point
thank
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