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
Okay, then I'll list what I bought then from Parts COnnexion!
2 Dexa Discrete Opamp Dual DEXA-73728 $84.95 $169.90
1 BURSON Dual Discrete Op Amp Modules, pair, (DIP Header) BURSON-74454 $179.95 $179.95
2 Dexa Discrete Opamp Single DEXA-73729 $49.95 $99.90
1 BURSON Single Discrete Op Amp Modules, pair, (DIP Header) BURSON-74456 $114.95 $114.95
In the U1/U2 position, how do the Bursons compare to the Dexas in sound quality?
I have been waiting impatiently for my Discrete Opamp Rolling article to be published at Dagogo.com; now it's up for the world to see.
It is my latest foray into Opamp rolling, this time with the lovely discrete Opamps.

A couple of notes:
There was one mental faux pas where in comparison of prices I said, "ten digit" but meant ten thousand or five digit. Should get corrected today.

I focused on redbook playback in the article, but the same results apply to the DAC being used with file playback, streaming audio, etc.

I did not get into the option of shortening the long leads of the Burson Opamps, but I have indeed spoken to Burson/Dexa to obtain additional sets for my office rig. I'm looking forward to that upgrade!
Following up on my threat (actually, a promise) to put the discrete Opamps in my office rig, the sound is good enough that for all but the most ardent perfectionists it would be quite acceptable.

My office rig: Sonos with a Buffalo .5G NAS for my CD collection ripped; Cambridge Audio Azur 840C, Peachtree Audio Nova, Eminent Technology LFT-VI with pair of SHU STF-1 subs. Wireworld cabling throughout. This is not what I would call an extreme system, but a competent one. However, the discrete Opamps installed into the EE DAC (this is the older version, not the Plus version as I wrote about in the article; the Plus version is much better holistically) elevates the system vastly. It sounds closer to what I accomplish in the review system than previously. Particularly the magnetic planar speakers are sounding much better than prior, more tight and distinct.

BTW, the tube mode of the Nova obscures the pristine nature of the EE DAC; I run the Nova with SS mode and the tube removed from the EE DAC.
I've been running the Dexas in my DAC + for about 6 weeks and there is no question that the discrete opamps produce a sound that is much more analog like than any of the IC opamps I've tried. Based on Doug's review I have also ordered the Burson discrete opamps and will do a comparision between the two when they arrive.

I will say that at least in my system (Shindo amp and preamp, Tonian Labs (12" PHY) speakers) some of the IC opamp combinations seem to have more absolute resolution than the Dexas but the Dexas just sound more natural with less listening fatigue.

I still prefer listening to my analog gear over digital but the DAC +/Dexa combo has greatly improved my digital listening experience. For under $2K, the sound has exceeded my expectations and represents an excellent value.

Will report back later when the Burson's come in...
Thanks to Bill for hooking me up with the DEXA's! They do exactly what I want in the sound, more relaxed AND more resolution. In essence they reveal more nuanced details, but do so in a way that makes extended listening even easier. I'll be doing some comparisons with my BMC DAC1, and while I don't expect the EE to come out on top, I do expect it will be very close in many ways.
The results with the original Minimax DAC in the office rig are as expected, beyond expectations. I have rolled in the Dexa duals into the U1/U2 positions and the Burson singles into the U6/U7 spots and the performance uniformly elevated across the frequency spectrum.

Particularly notable is the extra weight and definition with the bass. I have smallish subs in the rig but the Bursons, as with the reference rig, add quite a bit of robustness and presence without sacrificing definition. Tonality continues to improve as well.

Once again, note that one should roll both pairs of the original IC Opamps. Using discrete Opamps in all four locations dramatically improves performance, despite the fact that one could leave the stock IC Opamps controlling tube output untouched. Just as it may sound illogical to remove the tube, so also it seems illogical that replacing the IC Opamps for tube output would affect the overall performance, but it does, and in no small fashion.

This may prove to be among the most affordable answers to the "Class D Amp Problem", that being a white-ish, thinner sound. I am very much enjoying the performance of the Peachtree Audio Nova with the EE Minimax DAC now along with the Eminent Technology LFT-VI speakers. This is the best magnetic planars in an affordable rig have sounded in a long time. And I'm not even using Redbook, but Sonos with a NAS.

(I have reviewed products from these brands for Dagogo.com)
The other day i had the opportunity to compare my Minimax plus modified with the dexa's, psvane grade A tube and a Hi-Fi tuning extreme fuse, with a level 3 Lampi at a hifi store near me. The comparison was done with some large magneplanars(don't know the model no)and some other high end pre and power amps, if anyone is interested i can get the relevant info. Anyway i was very surprised to hear that the Minimax plus sound was so close to the Lampi level 3 in detail retrieval and tone, in fact in regards to detail i would say that they where identical and if there was a difference i couldn't hear it! tone wise the Lampi had slightly more body(by a very small amount)but the Minimax had better bass. Soundstage wise once again the Lampi one by a very small amount, one difference was that the Lampi placed everything a bit higher up(like they where up on a stage) and the Minimax was lower as if they where on the floor in front of you but other than that nothing else stood out as being majorly different.The guy who owned the shop was very impressed with the Lampi but still was more surprised with how the Minimax stacked up against it at the price it sells for.Needless to say i left the store a very happy man knowing just how good a dac this is for the $1100 i paid plus $360 in mods.These dexa's take the Minimax Plus to a whole new level do yourself a favor spend the money and enjoy an outstanding dac
Time for a quick update. I've been running my minmiax dac + with Dexas for about 3 months and thought they were a significant upgrade over any of the IC opamps I tried. After reading Doug's review, I decided to try out the Burson's and report back.

First off I'll list my system for reference. Preamp is Shindo Vosne-Romanee. Amp is Shindo Haut-Brion (25W). Speakers are Tonian Labs Classic 12's (96db speaker featuring PHY driver with supertweeter). When listening to redbook CD I used PS Audio PWT as transport. When listening via USB through my windows computer I used flac files via JPLAY.

When I originally read Doug's review I was a little disappointed and thought he was hedging his bets by not declaring a clear preference. After living with both the Dexas and Bursons for a while I now understand his position. The Dexas and Bursons are to my ears a clear step up over any of the IC' opamps I've used. In addition, the inclusion of the discrete opamps makes digital more listenable over an extended time frame. The digital "edge" is gone. The music sounds more analog like than ever.

That being said, the Dexas and Bursons clearly sounded different in my system. With Dexas, the sound was clearer and cleaner with greater extention in the higher frequencies. With the Burson's swapped in, the sound was weighter, with more meat on the bone. The low end was also more impactful. I realize I'm pretty well echoing the comments that Doug made in his article. He pretty much nailed it.

Which do I prefer? If a gun was held to my head and I had to choose one I would probably pick the Dexas today based on my system. My Shindo electronics do a good job conveying weight and body to the music so I like the clean sound of the Dexas. However, if your system is on the lean side, I can easily see you prefering the Burson's.

My next step is to mix and match between the Dexas and Bursons to see if the combo can give me the best of both worlds. Will report back again with my thoughts in a few weeks.

For those of you who have the Minimax or Mimimax plus, go out and get some discrete opamps ASAP. The sonic bang for the buck is as high as anything I've tried in the 20+ years I've been dabbling in this hobby.
Nothing1:

Agree with your asessment of the Dexas. You mentioned the level 3 Lampi had slightly more body than the Minimax. If you like that fuller sound, get a pair of Bursons. Compared to the Dexas the Bursons add (at least in my system) more body and weight to the sound. Having both Dexas and Bursons allows for tremendous flexibility.
inregards to the Lampi having slightly more body it was just a slight difference and was not really anything that concerned me, in my system with a Rotel RC-1550 pre and a Rotel RB-1582 with Wharfedale 9.6's that difference is gone but i still have an incredible amount of detail without any harshness. As you can probably tell I'm loving it
This is a crazy price difference but has anybody did a comparison to the AMR DP-777
After several days of mixing and matching the Dexas and Bursons in the Minmax plus it has become pretty clear that I prefer the Dexas in both U1/U2 and U6/U7 in both tube and SS mode. The Dexas have a crispness and clarity that I really enjoy in my system while being much less fatiguing than any of the IC opamps I've tried. Those looking for more body and weight to the music should try out the Burson's.

After a bunch of experimenting, my current default listening setting (subject to change) is tube mode with NOS Mullard and all Dexa opamps. In addition to the stock EH tube, I have tried Amperex, Mazda/Cifte and Mullard. I prefer the Mullard but all NOS were a clear improvement over the stock tube. Will more than likely try a few other tubes for curiosity sake. For those looking for the utmost clarity and resolution, going all Dexas in SS mode with tube removed is a great choice as well.

That's it for now.
With the exception of the discrete opamps, I perfer the 49990's. Would the Dexa or Bursons have the resolution of the 49990's with more body? Thanks
Hi,
I used the 49990s happily for several months on my Plus. I liked them a lot but tried the Dexas anyway (Bought from the mfr. site for about $245 total).
The upshot- I easily preferred the Dexas (after 50 hr break in). Interestingly, they sound most like the 49990s of anything I've tried- detailed, very fast and transparent.
But they also are a bit easier and organic sounding- not softer or rolled off, but more analog-like? They also do a better job of letting through the ambience and tiniest harmonic details. Overall, they sound a lot like the 49990s but more refined. Is it worth the $? To me they made the sound a bit more relaxed, which was what I was looking for. So in my case, yes, they were worth it. Day and night difference, once size fits all? Not in my opinion. Good luck!
I agree 100% with Jmbatkh's assessment. The discrete opamps I've tried (both Dexas and Bursons) sound more analog like than any of the IC opamps I've tried. I don't think you will necessarily get any more resolution with Dexas over 49990's but the presentation is more relaxed and organic. I can listen to the Dexa upgraded Dac Plus for hours without any listener fatigue.

The Dexas sound to me cleaner and clearer with more sparkle than the Bursons. The Bursons will add more body and weight to the music with better bass than the Dexas. Both are wonderful and dependent on personal taste.