Success Rolling Opamps in EE Minimax DAC


I'll try to reign in my nearly unbridled enthusiasm for a recent uber-economical tweak, rolling Opamps in the Eastern Electric Minimax DAC.

On encouragement of Chris and Melissa Owens from Clarity Cable I swapped them out (note; this voids the warranty!), with resounding success. A more powerful upgrade per dollar in decades of messing with systems and tweaks does not come to mind.

My brief instructional discussion on this experience appears at Dagogo.com

http://dagogo.com/View-Article.asp?hArticle=841
douglas_schroeder
My hour of darkness is finally over. I have finished my modification of the EE Minimax DAC.
Welcome to the sunny side of the street? Come now, you're being MODest; please share. :)
I started to post earlier, realized I didn't have time, so I will finish now (can I finish? can I finish? can I finish?)

The following is a klutz’s description of modding the Eastern Electric Minimax DAC via Doug’s recommended op-amp rolling:

I had been enjoying this DAC so much in its stock form that I was more than a little reluctant to monkey with it in the name of what? Futzing around? Flirting with audiophilia? Refusing to leave well enough alone? I had to ask myself – am I dissatisfied with the Minimax? Is there some aspect of its performance that I feel needs improving? The answer to both of these questions was ‘no’ so I tried to just shove the thought of a mod out of my head altogether. But I couldn’t do it. The seed had been planted: the mod was said to be cheap, simple to perform and effective so I picked up the phone and called Digi-Key.

Let me say that you will need more than the parts numbers given by Doug in his article. When I gave the phone person those numbers his computer came up with semiconductors costing over $100.00. I told him that couldn’t possibly be. The ones I wanted were only a couple of dollars. He had to get a tech guy on the line who was able to figure out what I was looking for. The complete parts number they are looking for is LME49710NA/NOPB and LME49720NA/NOPB.

I started to skip the op-amp extraction tool figuring I could use a pair of tweezers or something, thereby saving a couple of dollars, but that would have been a big mistake. You’ll need the extraction tool if you don’t already have one, so don’t cheap out here.

The parts came quickly but I didn’t move to perform the mod quickly. I continued to enjoy the DAC in its stock configuration. The old adage, “If it ain’t broke don’t fix it” kept coming to mind. But finally, last Tuesday night, I decided to go ahead and do what I knew I would inevitably do, but I definitely had qualms about what I was attempting.

I admit to being a klutz. I’m not a hobbyist or a mod person – at all. I’m a dilettante, an aficionado who just wants to listen to and enjoy the music. I’m gladly willing to pay someone else to do my killing for me. But Doug said that this was about a 1.5 on the difficulty scale so I decided, ‘what the hey, let’s open this sucker up’.

I took the Minimax to the dining room table armed with a powerful magnifier and a Phillips head screw driver to remove the cover of the DAC. This was the first moment of consternation when I discovered that the cover isn’t held in place by Phillips head screws. In fact, I’d never seen the type screw used here, but I finally found a mini screw driver that would remove the screws. This was already taking longer than expected. Upon looking at the circuit board through the magnifying glass, I looked and looked but could not find U1 & 2 or U6 & 7. After 10 or 15 minutes of looking I had just about decided that the circuit board designations between Doug’s and my unit were completely different. I thought the project would have to be postponed and I would post about this discrepancy.

Then, I finally saw the designated numbers. I admit that my workstation left a lot to be desired – a dining room table with a chandelier overhead. I was using a bright penlight along with the powerful magnifying glass, but a proper, well lit work station would be a definite plus.

I used the extraction tool to pull the first op-amp out. This was fairly easy and straight forward. I then tried to put the first replacement op-amp in. This turned out to be much more difficult than I had expected. With four straight legs on each side it seemed as if it would be a simple proposition to push it down into its new home. But nooooo. Nothing is simple and easy for me. Shining the penlight and using the magnifying glass I lined up the legs on one side and got them started going in. I thought I had them lined up on the other side and pushed. Ahhhh, that great feeling of sinking in up to the hilt. But then I noticed that the legs on one side had not gone in but were splayed out over the side! I pulled the op-amp out and tried again with the same result. Now I noticed that one of the four legs on the left side was bent a little. This is when I started to despair. I knew that if I couldn’t get the legs to go in while straight, I would never get them in with one bent. I imagined the leg breaking off if I tried to straighten it, and further imagined being without my DAC for awhile waiting for replacement parts to ship in. I thought that even if I tried to put the old op-amp back in, I probably wouldn’t be able to get it back in without bending and breaking it too.

But the gods smiled on me at this point. I was able to straighten the bent leg on the new op-amp and finally managed to push all eight legs in successfully. Wiping my brow I followed suite on the next 3. All of them presented some difficulty to me. When I would line up and begin to push the 4 legs on one side in, the 4 legs on the other side would want to splay out over the side. But I finally was able to seat the other op-amps without bending. Finally it was done! I’d have to say that if you are a klutz like me this will be more like a 5 on the 10 point scale of difficulty, but if you’re the normal audio enthusiast, Doug’s 1.5 is about right.

So, was it worth it? YES, YES and again YES!!! All I can say is WOW! This is indeed one cost effective and VERY worthwhile modification of the Minimax DAC. The openness and spaciousness of the soundstage is unreal: top to bottom, left to right, forward to back. There is now so much more depth to the soundstage. There is also more detail with a greater incisiveness than was there before.

On acoustic, small scale music, it’s like the ensemble is in the room with you. On large scale classical music, the broadened,deepened soundstage and heightened resolution are the best I’ve ever heard a symphony orchestra sound on a home stereo system via Redbook CD. A soundstage has to be big to accomodate a full symphony orchestra! There wasn't the congestion that you so often get when listening to orchestral music on Redbook CD.

I was worried that a modification might somehow take something away from the Minimax’s presentation of rock music. Its rhythmic drive and bass do wonders with rock music and since this is my “go to” music and the area where I had been enjoying the Minimax most, I didn’t want anything to change that aspect. I needn’t have worried. None of these traits are lessened; you just get the bigger soundstage and greater resolution.

What a great upgrade! Many thanks to Doug for making owners of the EE Minimax DAC aware of this modification. For me there’s no going back. I can’t stop listening and am enjoying Redbook CDs like never before. I would say, if you own the Minimax and haven’t done the mod yet, go for it. But if you’re a klutz like me, just be prepared for a little more time and effort into the equation. Definitely worth it. Thanks again Doug!
I too tried the op-amp upgrade you suggested Doug and it sounds quite phenomenal in my (all tube) set up. I still wonder, though, about the new "Custom National Semiconductor op-amps" you refer to in the Audio Blast update of 01/18, which you would move directly to. Can you give us more specifics?
Cheers
Ernst
Thanks for the feedback, gentlemen. Glad you are enjoying the upgrade.

But there's more to come; watch for another Audio Blast article. It gets better, much better.

In its stock form the Minimax has been well received, including one Product of the Year award. Yet, even reviewers do not know the potential of this DAC. I've been able to take it far past the normal operation and will share my experiences.

This DAC is very special. :)