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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
sibelius
256 posts
 
Update time. Have spent time with an all Dexa Discrete opamp system in both U1/U2 and U6/U7. Impression is that the sound is softer and rounder than the 2604/827 combo. It does a good job of taking the edge off harsh or bright recordings but does not have the same degree of detail or resolution of the 2604/827 combo.

If you want the most detail and resolution I would go with the original recommendation - swap out stock opamps with 2604/827 and remove the tube. It will cost you about $80 and is a noticeable difference.

If you want to tame some digital harshness, replace the stock EH tube with a good NOS tube like Mullard, Amperex or Brimar. If you want some more resolution, you can then swap out the stock U1/U2 opamps with 2604's.

I'm of two minds on the Dexa's. On one hand they are probably the most analog sounding opamps I've tried in the DAC but at about $250-$300 they are not great value.
morningstaraudio's avatar
morningstaraudio
154 posts
 
Only been playing them for a day, but immediately noticed going thru the SS output with tube removed and the dual OPA2604's still in the U1/U2 dual position with the single Dexa's in the U6/U7. Lovely smooth presentation, totally agree with Sibelius on the analog tone to this combo.
This morning installed the dual Dexa's in U1/U2 position and running that at the moment with a Siemens silver-plate thru the tube output.Really haven't had time to critical listen as now just doing some background music to burn in a bit.
Thanks to all of you who recommended these.
Later,
Bill
sibelius
256 posts
 
Yep, the smooth presentation of the Dexa's along with a NOS tube has won me over and I'm keeping this as my default set-up for now. It does not have the last degree of detail as the 2604/827 combo but it has enough detail and resolution for me while helping to reduce any digital harshness. Cost is only downside. It's $250-$300 for a full complement of Dexa's which may be a lot for people to invest on a $1100 unit. Never the less, I just love the flexibility of the EE unit.
mitch4t's avatar
mitch4t
1,602 posts
 
.
From the context of all the posts here, I have to assume that an opamp is the same thing as a tube or a valve. Is that correct?
.
sibelius
256 posts
 
No, an opamp is an electronic part on the circuit board of the DAC. Many DAC's have the opamps soldered to the board which makes it extremely difficult to swap out. The EE opamps are not soldered so swapping them out is very easy. Many people (I'm one) find that changing opamps (like changing tubes) can influence the sound. What's very nice about the EE is that between tubes and opamps you can fiddle to your heart's content and tailor the sound to what you like. The only caveat on swapping opamps is that this usually violates the manufacturers warranty if anything goes wrong.
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