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Eastern Electric Minimax DAC – Upgrading Op-Amps

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UPDATE 1/18/2011

Further investigation into op-amp rolling the Minimax DAC has been fruitful. I obtained these custom National Semiconductor op-amps for the EE DAC per recommendation from Chris and Melissa Owen of Clarity Cable, whose cables I am currently reviewing, and I consider this to be another efficacious improvement. This newest op-amp set is one I would absolutely put in the place of the previous, original Digikey National Semiconductor set; no comparison – the custom op-amps are much better. They are easier to install, as the legs are not splayed but fit perfectly into the sockets easily. This made changing them even easier.

For the meager cost of $13.90 the set, moving from the stock unit to them would be extremely beneficial for users of the EE DAC. The purity, texture, micro and macrodynamics, soundstaging, and especially surprising, the center image and stereo separation all improve significantly with the Clarity-sourced op-amps over the stock DAC.

Regarding the warranty of the EE DAC: Bill O’Connell had contacted me after a customer who perform the op-amp rolling complained that his unit was dead. This customer revisited the installation and found that he had in fact not gotten it right, but when redone the unit worked perfectly. I remind potential DIY’ers that this is a warranty-voiding activity and you are not free to call Morningstar Audio with your gripes if it doesn’t turn out. You are free to pay Morningstar to repair a defective unit. Morningstar does not promote or encourage the op-amp rolling, so they are not responsible.

Accepting that disclaimer, I am learning that the EE DAC is quite robust and seemingly not easy to hurt. I know of one instance where op-amps were put in the wrong location and when reinstalled correctly nothing was amiss. I think it would be difficult to actually harm the unit this way; much more likely you’ll dispatch the op-amp. I’m not a designer so I cannot say that definitively, but the feedback suggests this.

In conclusion, the Minimax DAC is great by itself, but is much better with the changed op-amps. As a monetary point of comparison, if the op-amp upgraded DAC were $100 to $150 more expensive and I compared them I would not hesitate to pay the extra for the improved version. Having heard the op-amps referred to in the article and now the custom op-amps, I would move directly to the custom op-amps, and recommend those interested to see their unit “maxed out” with this tweak to do the same.


Just enough time for one more upgrade… Last night I installed four little wonders into the Eastern Electric Minimax DAC – a bit of op-amp rolling. It’s bonus time for owners of the Minimax. For under $20 you can impressively improve the nature of your Minimax DAC by “rolling” (changing out) the op-amps inside! You likely have heard of “tube rolling”. To my ear this swap of op-amps has made a more profound change than any tube rolling I have tried.

It’s straightforward. You use an op-amp extraction tool to remove the old ones from their sockets and replace carefully with the new. You may need a magnifying glass to see the tiny lettering on the circuit board of the DAC. Here is what I bought from

Two (2) National Semiconductor LME49720 8-pin op-amps to go into the U1 and U2 positions on the DAC’s circuit board;

Two (2) National Semiconductor LME49710 8-pin op-amps to go into the U6 and U7 positions on the DAC’s circuit board;

One (1) op-amp extractor tool, about $2; I got the one that looks like a tweezer, with a yellow rubber grip.

The upgrade radically changes the nature of the DAC, akin to a heart transplant. This is a prime example of what I consider to be an upgrade which easily passes my Law of Efficacy. I find many upgrades/tweaks to offer so little improvement as to be negligible. When I want improvement I want serious change, not some wussy, I-think-I-hear-a-difference change. This instance of op-amp rolling is a terrific, no-brainer-priced upgrade which offers a powerful change to an already good product.

Total cost of my upgrade, including shipping via postal mail: $13.90. Taking my time to be careful in placement of the tiny legs of the 8-pin chips as I inserted them, the project start-to-finish was easily under 20 minutes. It falls into the category of an ultra-easy tweak.

Warning! The extractor tool I obtained has a long neck on it, so it is possible to reach too far under the op-amp and grasp onto the socket! Watch closely that you’re pulling the op-amp and not the socket it sits in! Go slow, you’ll be fine. Of course this will void your warranty, so only you can make the decision. Consider, however, that this is an economical component and that this act approaches foolproof DIY. Unless you were truly careless you would be hard pressed to wreck anything important; if you are too hasty you may bend the leg(s) of the op-amps when inserting them. Ok; that’s about $2.00@ for replacement. If you have a phobia about the innards of components, consider that I have never previously op-amp rolled, and have done some but not extensive soldering (i.e. soldered leads on drivers in speakers). On the scale of difficulty for someone with basic competence in things mechanical, this rates about a 1.5 out of 10.

I’m most pleased that Alex Yeung, the Minimax DAC’s designer, chose to use socketed op-amps – a serious upgrade decision for audiophiles. He has provided a bona fide easy, potent DIY tweak which any owner can benefit from with little risk and big returns on money and time. Kudos to you, Alex!

This is all initial discovery; the results are so profound that they deserve comment immediately. Those looking for a “larger experience” in soundstage from the Minimax are going to be pleasantly surprised. I’m looking forward to dialing it in via establishment of different systems. I’m also very curious how it will sound with big panels.

Thanks to Chris and Melissa Owen at Clarity Cable for their guidance on Op-amps and instructions for replacement. I reviewed their cables recently, and this additional excursion into “DIY for Beginners” is fun!

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One Response to Eastern Electric Minimax DAC – Upgrading Op-Amps

  1. Scott says:

    Having replaceable opamps is a nice feature. I’ve been doing some research (reading/rolling) on opamps and have found that, as you’ve noticed, many different opamps have different “audio signatures”. Like with speakers that are “bright” or “dark”, different opamps would have different affects (make the music appear “brighter”/”darker”), so they could be matched with your system to optimize its sound.

    Because of this, many people play with two or three sets of opamps to find one that is optimal for their system. The advantage is that they are a dirt cheap way to a potential huge sound improvement!

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