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Listing of Opamps for EE Minimax DAC Plus

Phil from Cimmaron Technology sent me a list of approved Opamps for
respective positions on the board of the EE Minimax DAC Plus; prices
include the Brown Dog Adapters provided by Cimmaron. I have been using
in the U1/U2 position the OPA2604 and in the U6/U7 position the OPA827.
I have not Opamp rolled this unit much, as I have been busied with other
components for review. I attest that the DAC Plus in SS output with the
tube removed and these opamps is sensational.

(NOTE CAREFULLY the warning at the bottom NOT to use the AD 8620 in the U1/U2 positions!) Also note that the positioning of the opamps/adapter is always with the small square solder point on the topside of the Opamp at the upper right hand when the unit is facing the installer. Finally, it is recommended that an opamp extraction tool and an anti-static device be used when removing/installing Opamps.

Is it "worth it"? YES! YES! YES! :)

RECOMMENDATIONS OF OPAMPS FROM CIMMARON TECHNOLOGY:
For U1/U2
Single-channel op-amps mounted on the 020302 SO8-to-DIP8 single-to-dual
channel adapter:
qty 2 each required

020302-OPA627 $48.00 x 2 = $96.00
020302-OPA827 $38.00 x 2 = $76.00
020302-AD797B $48.00 x 2 = $96.00

. . . also for U1/U2
Dual-channel op-amps mounted on the 970601A SO8-to-DIP8 adapter
qty 2 each required

970601A-AD8620 $23.00 x 2 = $46.00
970601A-OPA2604 $13.00 x 2 = $26.00
970601A-OPA2134 $10.00 x 2 = $20.00

For U6/U7
Single-channel op-amps mounted on the 970601A SO8-to-DIP8 adapter
qty 2 each required

970601A-OPA627 $28.00 x 2 = $56.00
970601A-OPA827 $23.00 x 2 = $46.00
970601A-AD797B $23.00 x 2 = $46.00

The AD 8620 should not be used in the DAC PLUS.
"On some forum there was a suggestion to use the AD8620. for positions U1
and U2. While this is a dual op-amp, it is only rated to use up to
plus/minus 13 volts. The circuit in the EE Mini Max DAC and DAC Plus is
plus/minus 15 volts."
douglas_schroeder
morningstaraudio's avatar
morningstaraudio
154 posts
 
I wrote Alex a week or so ago regarding the use of the Burson's.
Here is his reply.

Hi Bill,

Sorry for my tardy reply, I was away. I checked the Burson web site, it said clearly
that their dual one can replace the NE 5532 and the single one can replace the NE
5534. So they will work just fine with the DAC and The Plus.

Thanks.

Best regards,

Alex
skomak
4 posts
 
Thank you Bill
I will report my findings when I got the opamp. I was concern regarding the voltage compatibility.
mrtennis
3,295 posts
 
although, indirect;y related to tyhis thread, there have been commemnts regarding the superiority of listening to the minimax, bypassing the tube stage and removing the tube.

considering that there are some "good" 12au7s available, in what way does the removal of the tube improve the sound ??
sibelius
256 posts
 
I've not heard anything definitive from EE, but one theory is that the power supply would see less of an overall load and perhaps lower noise level on power rails to opamp.

Whatever the reason, I've tried the tweak and do find it an improvement.
josefm
53 posts
 
Same* result here, SS output is much improved with tube removed...however, with the right tube (system compatibility) I prefer the 'fleshier' output of the tube stage.
I found no real measurable (by ear)improvement to the tube output with the removal of the SS opamps. My guess would be that the tube stage draws more juice from the p/s vs the SS output opamps.
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