Darlington Labs MM-6 Phono Preamplifier Review

HiFi Guy

HiFi Guy

All Things Audio
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Behind the phono cartridge, a system’s phono preamplifier has the second most difficult job in an analog lover’s system, and is often overlooked. The phono preamplifier’s job is twofold. First, it amplifies the tiny voltage put out by the phono cartridge to a voltage high enough for the amplifier to work with. Secondly, it performs RIAA equalization. Without equalization during the mastering process, the long playing LP couldn’t exist. Bass is cut and treble is boosted when the lacquer is cut, and this is passed on to the final LP. The phono preamplifier reverses the bass cut and treble boost, and needs to do it accurately, while (hopefully) adding as little error during the process and as little noise as possible. One may have this function built into their amplifier, or there are a wide variety of outboard units available from as little as under $50 to as high as $65,000— I’m not kidding. Features, build quality and design philosophy differ, but basically they all do the same thing. How well they get the job done- now that’s a different story.

There are three basic ways to build a phono preamplifier. The most common is based around a variety of off the shelf integrated circuits. Then there are tubed units. A word of caution here: I wouldn’t consider a tubed unit under $1000 and even then, the one I’d ultimately buy is $2800. The one I lust after is nine grand, give or take. There are some very inexpensive tube phono preamps on eBay. Those should be especially avoided. Not only are they quite poor in performance, some are actually unsafe. The third way to build a phono stage would be using discrete components- solid state without the use of integrated circuits. Obviously, this is more difficult (and expensive) to design and build, and is usually reserved to units starting around $1000. Some feel discrete units offer the highest performance.

The Darlington Labs MM-6

Darlington Labs are the new guys on the block. That doesn’t mean inexperienced: they have well over a half a century in analog experience shared between the members of the team. Based in Massachusetts, they offer three models of phono preamplifiers priced from $129 MM-3 to the top of the line MM-6 under review priced at $329. What sets them apart from their competition is that all of their products are discrete and built in the United States. To the best of my knowledge, they are the lowest priced such designs on the market. Parts come from variety of vendors, with a few non-critical parts coming from China to keep the costs in check.
 
The MM-6 is rather plain in appearance, but built to a high standard. The only control on it is a rear mounted power switch. Oh, I need to mention that the MM-6 (like all of Darlington’s designs) are for use with high output cartridges only- low output designs need not apply. I see this as a smart move. Instead of having a phono stage that is jack of all trades and a master of none, the Darlington Labs units concentrate on getting the best performance possible from one type of cartridge. Besides, what’s the use of paying for low output moving coil compatibility if it won’t be used? That same money could be used to enhance the performance of the unit when used with high output cartridges, which is what has been done here. That doesn’t mean that choosing a Darlington Labs unit means you’ve driven down a dead end. They will soon introduce an active step up device that will allow the use of low output moving coil cartridges with any of their phono preamplifiers.

The power supply is built into the MM-6 chassis, and is fed by a step down transformer. Although it looks like a wall wart, it really isn’t. The MM-6 is a AC design that operates at 24 volts. The transformer reduces the 120 volts from the wall down to 24 volts. Other companies’ designs often require conversion from AC to DC as well, which increases complexity and reduces reliability. Additionally, removing the transformer from inside the chassis eliminates the possibility of radiated noise from the transformer to the sensitive audio circuits. Overall, a very smart design choice with no obvious disadvantages. Roughly half if the MM-6’s circuit board is dedicated to the power supply.

Darlington Labs also offers units that can operate on other voltages as well for those living overseas.

As far as the circuit itself, you’ll want to visit their website to find out why they feel that specially selected New Old Stock J-FET transistors are the best choice for a high performance phono stage. What I found most interesting was that the MM-6 uses no negative feedback. Without getting too technical, negative feedback is often added to a circuit to achieve a couple of goals. It can improve the specs by reducing total harmonic distortion. It can also add stability to an otherwise unstable circuit. My experience is that units with high negative feedback don’t sound as good as those that don’t. They tend to be less musical and less involving- less like natural music. Most manufactures won’t even publish their negative feedback figures- only the ones with low negative feedback will. Better published specs do not always equate to better sound. One of my favorite integrated amplifiers (Manley Labs’ Stingray) has around 5 dB of negative feedback (very low) and pretty dismal published specs. One listen though, and it’s obviously special. The Darlington Labs units are a rare breed indeed: they have both zero (!) negative feedback and yet have excellent published specs.

I auditioned the MM-6 with two cartridges: the Grado Gold3 moving iron ($260, 5 mV output) as well as the Dynavector DV10X5 high output moving coil (NLA $650 when last produced, 2.5 mV output.) I had no issue with getting enough volume with the Dynvector, and the Grado worked as expected.
 
Don’t look for a fancy manual. In fact, no manual is supplied- fancy or otherwise. There’s a wealth of information on their website. Setting up the MM-6 couldn’t be easier. The back panel has a pair of inputs and outputs, the ground connector, a jack for the power transformer and the power switch. There are no adjustments, so a manual really isn’t needed.

When I asked Darlington Labs’ president and chief designer Keith Richardson about break in, he told me that takes about a week. He also said to leave it on for the first 72 hours. I’ll go farther than that: just leave it on. You’ll not see an increase in your electric bill as there’s very low current draw. I did notice a big jump in performance during the first 72 hours.

In Use

As I haven’t had a phono stage priced under $1400 for a number of years, I was pleasantly surprised how quiet the MM-6 is. At first I didn’t think it was powered up. It passed my first requirement with flying colors. Low noise levels will allow music buried deep in the mix to come through. A noisy phono stage will rob the listener of some of the beauty that vinyl offers. The MM-6 was far quieter than I expected given its price, and extremely quiet in absolute terms, regardless of price.

Tonally, the MM-6 was very well balanced from bottom to top. It didn’t artificially add punch to the bottom registers. Midrange was clean and clear, with extended high frequencies - much more with the Dynavector than the Grado. It didn’t seem to favor one genre over another.

It did do one very interesting thing: as the hours racked up, developed a midrange “glow” not unlike vacuum tubes. I had a pretty amazing experience totally by chance one sunny Sunday afternoon with the Grado on the business end of the tonearm. I decided to check out some Nat King Cole. He recorded a lot at Capitol Records Studio A in the later 1950’s. Not only could I tell there were vacuum tubes in the recording chain, but I could nearly feel their warmth. When I put the album back on the shelf, the next random connection I made was to get the current reissue of Frank Sinatra’s “Come Fly with Me.” It hit me like a ton of bricks: the Cole album and the Sinatra album sounded exactly the same. Not that Cole and Sinatra sound the same, because obviously they don’t. What was the same was the recording space, the tube sound, the reach out and touch the performers “you are there” right down to nearly feeling the warmth of the tubes. I knew the answer before Google verified it: the Sinatra album was recorded in 1957 at….you guessed it…Capitol Records Studio A. I was stunned. I’d never made the connection at all- much less figured it out from simply hearing it. On any system, regardless of price. Ever. I’ve tried to recreate it with my Sutherland and the Grado. No dice. I’ve tried it with my Sutherland and a much more expensive cartridge (Hana MH- $1200) Nope. If you’ve got a Grado, you’ve got to hear it with the Darlington Labs MM-6. That combination is flat out amazing.
 
The Elephant in the Room

The only other phono stage I had on hand for comparison was my personal unit- the $4000 two chassis dual mono Sutherland Duo. Expensive? Yes. But I’d recommend it all day long and twice on Sunday for someone like me- vinyl obsessed and maybe just a bit OCD when it comes to their system.

So this is the part where I tell you that the Sutherland wiped the floor with the Darlington, right? Not exactly. The Sutherland is better. It is quieter- but the Darlington is no slouch in this department. It has better measured performance as far as deviation from a perfect RIAA curve. And with critical listening, it does sound better. But not only did the MM-6 not get embarrassed by the Duo, it was shocking to me how close the two were to one another. The main difference was instrument placement within the soundstage. Where the MM-6 did a really fine job, it was outclassed by the Duo: left, middle and right became more defined- general areas became precise and firmly planted. Front and rear placement was better with the Duo as well, but again, not to anywhere near the extent that the price difference between the two might lead one to expect. Not only was the MM-6 not embarrassed, it was actually competitive. The MM-6 is underpriced compared to the rest of the market. The Sutherland is a good value at $4000, but the Darlington Labs simply does not sound like one might expect for $329. Even considering its high output cartridge limitation, my opinion would be the same if it were $500 or even $600. Keep in mind, the Sutherland does offer excellent MC capability, something the Darlington Labs unit lacks. But if you aren’t going to use it, why pay for it?

I’ve heard many of the units priced near the MM-6, some above and some below. I’ve even owned a few. Before you spend $150 on that overhyped phono stage (you know the one) consider this- that’s an entry level unit, one which may soon become dissatisfying. It would be a far better buy to spend $329 for the MM-6 and be happy long term.

Summing Up

I can’t recommend the Darlington Labs MM-6 more highly, even for those who have budgeted more money. I’ve personally not heard anything better under $1000 when using high output cartridges. It’s well built and its performance far exceeds its extremely reasonable price. I’d love to see (and hear) what Keith Richardson and the rest of the Darlington Labs team could do without the extremely tight budget constraints.
 
Manufacturer’s Comment

Thank you very much for the thorough and insightful review.

We offer a 230V power cube with EU style plug for countries that need it, at no extra cost.

Keep in mind that our true high-voltage J-FET input stage retains it’s low-noise ability even with high-inductance cartridges. The Grado cart used in the review is rated at 45mH, while other common MM carts are much higher; for example, the Ortofon 2M Blue at 700mH. The Sutherland, like other units using a bipolar transistor input stage (theirs is integrated into an IC chip) produce more noise as the cartridge impedance rises towards the high frequency spectrum, near the cartridge resonance. S/N testing is usually conducted with a fixed resistor, sometimes 1K or not specified. Our design shines in the real world with a variety of cartridges, the vast majority of which are high inductance (including, practically speaking, the results of coupling to many SUT’s).

Users report good results with the MM-6 using cartridges down to 1.5mV output (without using a step-up, assuming the rest of their system is sufficiently sensitive) and one of the most frequently cited comments is “low noise”. For lower output carts, we are developing an active MC gain stage which will pair with the MM-6 and hope to introduce it at our AXPONA booth in October. We have also had excellent feedback from users with Low-Output moving coil cartridges (LOMC) who are using the MM-6 with various Step-Up Transformers (SUT’s) with good results.

Our product roadmap does includes future products, so we invite readers to check our website occasionally for future developments.

We sincerely thank you for the review and interest in our products.

Sincerely,

Keith Richardson

Director of Engineering
Darlington Labs LLC
 
HiFi Guy said:
The Elephant in the Room

The only other phono stage I had on hand for comparison was my personal unit- the $4000 two chassis dual mono Sutherland Duo. Expensive? Yes. But I’d recommend it all day long and twice on Sunday for someone like me- vinyl obsessed and maybe just a bit OCD when it comes to their system.

So this is the part where I tell you that the Sutherland wiped the floor with the Darlington, right? Not exactly. The Sutherland is better. It is quieter- but the Darlington is no slouch in this department. It has better measured performance as far as deviation from a perfect RIAA curve. And with critical listening, it does sound better. But not only did the MM-6 not get embarrassed by the Duo, it was shocking to me how close the two were to one another. The main difference was instrument placement within the soundstage. Where the MM-6 did a really fine job, it was outclassed by the Duo: left, middle and right became more defined- general areas became precise and firmly planted. Front and rear placement was better with the Duo as well, but again, not to anywhere near the extent that the price difference between the two might lead one to expect. Not only was the MM-6 not embarrassed, it was actually competitive. The MM-6 is underpriced compared to the rest of the market. The Sutherland is a good value at $4000, but the Darlington Labs simply does not sound like one might expect for $329. Even considering its high output cartridge limitation, my opinion would be the same if it were $500 or even $600. Keep in mind, the Sutherland does offer excellent MC capability, something the Darlington Labs unit lacks. But if you aren’t going to use it, why pay for it?

I’ve heard many of the units priced near the MM-6, some above and some below. I’ve even owned a few. Before you spend $150 on that overhyped phono stage (you know the one) consider this- that’s an entry level unit, one which may soon become dissatisfying. It would be a far better buy to spend $329 for the MM-6 and be happy long term.

Summing Up

I can’t recommend the Darlington Labs MM-6 more highly, even for those who have budgeted more money. I’ve personally not heard anything better under $1000 when using high output cartridges. It’s well built and its performance far exceeds its extremely reasonable price. I’d love to see (and hear) what Keith Richardson and the rest of the Darlington Labs team could do without the extremely tight budget constraints.
Click to expand...
Highly enjoyable review @HiFi Guy! I suddenly feel itchy and twitchy about my second system....
 
Great review, I'm really enjoying my MM-6.

I would add that anyone buying this unit should consider customizing the front panel LED. From their FAQ:

Changing the LED color and/or brightness on our MM-6 or MM-5 is a no-cost option at the time of manufacture.
Color Options: Blue is standard. Red, Yellow, Green, or White are available.
Brightness Options: Medium is standard. Dim is available, whereby the indicator is not really visible in the daytime in direct sunlight but is truly ideal for non-distracting night-time viewing in a darkened room. ‘Medium’ has proven suitable for the majority of users.

My unit has the standard LED, blue/medium. I do most of my listening at night in low-lighting, and I find this to be a little bright. If I could do it again, I would choose yellow/dim, to match my TT.
 
dansomeone said:
Great review, I'm really enjoying my MM-6.

I would add that anyone buying this unit should consider customizing the front panel LED. From their FAQ:

Changing the LED color and/or brightness on our MM-6 or MM-5 is a no-cost option at the time of manufacture.
Color Options: Blue is standard. Red, Yellow, Green, or White are available.
Brightness Options: Medium is standard. Dim is available, whereby the indicator is not really visible in the daytime in direct sunlight but is truly ideal for non-distracting night-time viewing in a darkened room. ‘Medium’ has proven suitable for the majority of users.

My unit has the standard LED, blue/medium. I do most of my listening at night in low-lighting, and I find this to be a little bright. If I could do it again, I would choose yellow/dim, to match my TT.
Click to expand...
You can always tuck it away. It runs cool so you can just leave it on.
 
Great write up @HiFi Guy as usual. I was unfamiliar with the company and their products until you brought them to my attention. I dig their philosophy and approach in product design. I'm off to have a think on this for a bit, I wasn't planning an upgrade any time soon, but this has me curious.
 
I'm 48 hours in with the MM6. This thing is pretty ridiculous, especially for the money. Detail is outstanding. Soundstage and depth are impressive. The thing I can't get over is how quiet this thing is. Sometimes, as far as noise is concerned, I feel like I'm actually listening to a CD. It's that silent. Crazy.
 
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