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Eastern Electric MiniMax tube DAC Supreme: Discrete opamps Survey

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Also Read Eastern Electric MiniMax DAC Junior and DAC Supreme Review


Introductory pleasantries

Perhaps by now, due to the extensive amount of discrete opamp rolling I have done with the Eastern Electric MiniMax line of DACs I am something of an authority on the topic. I do not profess to be an electronics design authority, but a very experienced user of discrete opamps in system building. As such, I am not the person to go to when a question of compatibility of a certain opamp for a given DAC arises; see your distributor or manufacturer for such inquiries.

However, having built dozens of audio systems and tuned them by rolling discrete opamps, I can speak with some authority on the nature of their sound, and give guidance as to how best to use them. Indeed, the notion that one simply selects a brand and drops them into the unit is accurate – if that’s all you wish to do. You will see improved performance, assured by the quality of the opamps. However, if you want to turn the EE DAC (my most recent review-worthy model is the MiniMax Tube DAC Supreme) into a monster of a component, fit for extracting superior sound with any system then you need to heed the tenor of this article.

As I have written extensively on this subject, beginning years ago with rolling integrated circuit (IC) opamps into Eastern Electric DACs, up until now when I exclusively use discrete opamps, I ask the curious to do their homework on the subject before sending me requests about specifics of selection and insertion of opamps. You should find most of your questions answered in the previous articles. This article will focus on the flavor of three brands of discrete opamps, namely DEXA NewClassD, Burson’s new Supreme Sound 4th Generation offering, and a newcomer, Sparko’s Labs. I will give additional discussion to Sparko’s Labs in this article as the company is new, and it deserves the same attention I gave to the other brands.

There are a lot of options for rolling opamps, and the current Eastern Electric DACs have their individual needs; the MiniMax Solid State DAC Jr requires a pair of single opamps, which are oriented in opposite directions. The MiniMax Tube DAC Supreme requires a set of single as well as a set of dual opamps. They are all oriented in the same direction, with pin #1 toward the front of the unit.

Though the unit sounds better with the tube removed, as indicated in the review of these units, I find that there is still terrific benefit, and great flexibility in contouring the sound, to rolling in both sets of discrete opamps.


New kid on the block, Sparko’s Labs

Nicknamed “Sparko”, Andrew Sparks has extensive circuit design experience such that he felt the rather large discrete opamps on the market, some of which might not fit into the chasses of certain DACs (Earlier Eastern Electric DACs among them), could be improved upon. He set out to build a smaller, yet better sounding discrete opamp, and came up with his SS3601 Single and SS3602 Dual products. These operate in the same locations for single and dual opamps in the Eastern Electric DACs, as well as with many other brands. Consult with Sparko’s Labs on the appropriate opamps for your application.

Discrete opamps are one of the more curious aspects of reviewing for me, as they are wonderfully unique and confer such powerful results! I enjoy showing visitors the surprisingly different appearance of the DEXA, Burson and Sparko’s Labs opamps, as they bear little relation to one another. It would seem that products appearing so radically different could not perform the same functions. Yet, they all are designed to work in the specified socketed opamp locations in the Eastern Electric DACs. Andrew used extremely small circuit board layout such that his discrete opamps are about the width of a dime, and not much thicker than a stack of four or five of them. This allows for placement in some DAC circuit boards where other electronics populating the board might prohibit the insertion of a discrete opamp.

Andrew was one of the most helpful people to me in the journey of discrete opamp rolling. Previously I had always used the discrete opamps as they were delivered, typically with a black plastic base having a tiny half-moon shaped cutout on one end. The cutout marks the location of pin 1, which orients the opamp in the DAC. The alignment is easy; simply match the “moon” end of the opamp to the similar end of the socket in the DAC.

Another way to identify which end of these Sparko’s Labs opamps has Pin #1 is to look on the top of the circuit board for the “L” shaped solder joint. Compared to the other solder joints it appears thick and looks like a fat block letter “L”. There is nothing else quite like it on the top of the circuit board, so it is easy to find. The “L” is on the Pin 1 end for both the single and dual discrete opamps, and when placing them it goes toward the front of the DAC Supreme.

One sonic characteristic of the Sparko’s Labs opamps was that they seem to have higher gain than the DEXA or Bursons. With my TEO Audio Liquid Pre, a passive preamp, I had to turn down the volume control of the preamp a couple notches when using the Sparko’s opamps. This might be good news for some who find that their preamp is a bit short on gain.

On one occasion I was attempting to remove a DEXA opamp from the DAC, and the pins of the opamp seemed to be in tighter formation than with any previous EE DAC. I pulled until I had removed the opamp, and then continued removing the others. When I later was going to roll in the DEXA opamps I discovered that upon removal the black base (Actually, an extender; Andrew employs them as a protection device in shipping) was left stuck in the DAC. The DEXA opamp didn’t seem to have on itself a clear marking as to which end had Pin 1. It took quite a bit of searching online to discover that there is a wee small semi-circle on the top circuit board at one end. That tiny marking, nearly invisible to the naked eye, was the indicator for Pin 1!

In the process, because I am always thinking of shortening the circuit path, I considered that perhaps removal of the black extenders would improve the sound. The opamps themselves have the same pins, so I gave it a try, and it worked! The sound did improve somewhat, well worth the scant effort. I asked Andrew about it and he said the opamps were designed for use without the black extenders! All these years no one had ever told me that. Immediately I commenced using all of them without the black half-moon extenders.

WARNING! Be forewarned, however, that you must become intimately familiar with identifying which end has Pin 1! If you put any of them in backwards (180 degrees opposite the correct pin location) all of the pin locations will be wrong and you will damage the opamps, and very likely the DAC as well. Again, as with all my articles on opamp rolling, NOTE WELL: DO DISCRETE OPAMP ROLLING, OR REMOVAL OF THE BLACK BASES, AT YOUR OWN RISK.


One incident

I had one incident with the Sparko’s Labs discrete opamps, and it was not the fault of the designer or DAC. I have gotten used to quick removal of the discrete opamps; I used to rely upon an opamp puller, but have gotten lazy and use my fingers. One time I pulled on a Sparko’s Labs opamp and it came out on an angle, causing two of the oh-so-tiny legs to bend severely! OUCH! I chastised myself, thinking why did I ever take off those black extenders? If one of them is damaged, it’s a cheap part to replace, but if a leg of a discrete opamp is broken off or cannot be realigned, the cost is a new opamp! I took an excruciatingly cautious approach to bending back the legs, and it worked, they did not break off. That opamp is still in use at the time of the writing of this article.

When I place opamps I have a flashlight handy to shine on the opamp’s legs, and socket of the DAC into which it is placed, so that I can make the alignment perfectly. The legs of an opamp can also be damaged irreparably by misalignment and forcing he opamp downward. Take your time doing these things, as there is no prize for speed in this endeavor.


Listening impressions of Sparko’s Labs discrete opamps

As said earlier, I have covered some products from DEXA and Burson previously, so I will share a bit more extensively on the sound of the Sparko’s products. I used the following system for assessment: Mac Mini playing iTunes (This was before the arrival of the wonderful HQPlayer software), Clarity Cable Organic USB 1M, EE DAC Supreme with all Sparko’s opamps, Clarity Cable Organic RCA Interconnects, Pass Labs X600.5 Mono Amplifiers, Silnote Anniversary Speaker Cable, bi-wire set, Vapor Audio Nimbus White Speakers. Power cord on the EE DAC was Silent Source The Music Reference, and for the amps the power cords were Silnote Poseidon GS.

My playlist for assessment included Steve Winwood’s “Can’t We Live Together?”, Eva Cassidy’s “Stormy Monday”, Jason Mraz’s “The Boy’s Gone”, and Stanley Clarke’s “The Learning Curve”. Overall, the Sparko’s opamps are smooth, refined, and made the Pass Labs amps sound beefier and more balanced tonally from top to bottom. The frequency spectrum seemed quite well balanced top to bottom, and I detected no holes or hot spots. The macrodynamics were exemplary, superior to the DEXA and Bursons. Headroom was massive compared to previous discrete opamp tests. The soundstage was pushed a bit more forward, and while clean, was not ruined by piercing treble. Eva Cassidy did not sound like a schoolgirl, as can happen when the treble is tipped up. Stanley Clark’s electric bass seemed to reach particularly low, but exquisitely clean such that it was easy to hear the strings vibrating.


Compared to DEXA newclassd and Burson 4th Generation

The Sparko’s opamps are distinguished by two primary differences from the DEXA opamps; they are more detailed and increase the gain of the DAC. This results in a more forward, vibrant sound, a bit less analogue-like and more like good digital sound. The added gain is welcome when one is using a passive preamp, as I use the TEO Audio Liquid Pre. I found that with the Pass Labs X600.5 Monos when I used the Liquid Pre without any attenuation there was a pronounced hum perhaps caused by the DAC or the Mac Mini upstream exacerbated by the tremendous 600wpc of the X600.5. However, when I placed the Sparko’s opamps into the EE DAC I was able to achieve similar listening levels even though I dialed back the TEO preamp one detent. A single detent might not seem all that much, but the effect was to cut the noise in half, a very significant improvement.

Again, with speakers demanding more power, such as the Kingsound King III electrostatic speaker, the extra gain accorded by the Sparko’s Labs opamps allowed me to drive the speakers with a great deal of authority when the Wells Audio Innamorata was in use. This was a boon for music from artists such as America and Jim Croce with quieter recordings. Previously, I had two of the Wells Audio amps and could push the speakers harder on quiet recordings, but with only one amp there was not enough power to obtain the same listening level. The Sparko’s opamps helped to regain some of the forfeited power and dynamics.

The Burson 4th Generation opamps are the brightest and most tipped toward the treble. They are the most detailed as well; however, with very revealing gear they can push the sound a bit too far into the “hot zone,” where music becomes fatiguing after an hour or so. The images of instruments and voices of the Sparko’s Labs opamps are more solid than those of the Burson opamps. The Bursons do typically extend the soundstage a bit deeper and have an extra touch of microdynamics, but it comes with the tipped up tonality. The Burson opamps confer a more SET amp and high efficiency speaker-like quality, while the Sparko’s opamps are less so.


Which is the best?

My answer is not evasion; they all are superb, and all are recommendable. I insist that the most advantaged position an audiophile can be in is to buy them all, such that every conceivable option is available. With use, the owner can “cook” with the discrete opamps, learning the benefit of placing a single or double DEXA, Burson or Sparko’s opamp into the DAC to tune the rig.

The power of such configurability is not to be underestimated. Several times I have had friends or dealers loan me DACs, and in every instance I have been able to nearly replicate the sonic signature of the loaned DAC simply by rolling combinations of these discrete opamps. Though the spatial qualities of the soundstage and absolute precision of the DACs may differ slightly, the EE DAC Supreme can be made to mimic some DACs costing two, four or even more multiples of dollars. The ability to adapt a system to dynamic, panel and even omnidirectional speakers is unique in my experience. I have never encountered another product that morphs so brilliantly to accommodate disparate designs and listeners’ tastes.

Now that the DAC Supreme can operate at up to 6.1 MHz, the power of the discrete opamps and mixing them is leveraged even more. The effect is not unlike putting turbo on a sports car. As long as care is taken to insert the opamps, there is no obvious downside to this method. It is eminently efficacious, supremely recommendable, and one of my favorite methods to achieve a superior audio system! Best of all, it is affordable!

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3 Responses to Eastern Electric MiniMax tube DAC Supreme: Discrete opamps Survey

  1. mrvco says:

    Doug – Thanks for all the discussion regarding the EE DACs and op amp options. I have a DAC Supreme on the way as I type. I know you said you pulled the stock tube on your DAC Supreme, but have you experimented with any alternate tubes (NOS or otherwise)?

  2. Simon Andrew says:

    The extra gain with very low distortion in the Sparkos is what really makes them special. Everything I have used them in has an added bounce and openness.

  3. Mark Labbett says:

    Does anyone know who manufactured the USB DAC board I thought it was M2Tech but they are saying that they didn’t

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