When is it time to consider adding a SUT?

I have an ARC reference phono 2 and am about to take possession of a Benz LPS with a low output. I have heard that installing a SUT such as one from Bobs devices can help the phono pre and provide better end to end performance. Would this help a quality phono pre like the ref 2?

Depending on whether you’re running the cart in balanced or unbalanced, the Ref 2 will give either 74 or 68 dB of gain(respectively), which SHOULD be plenty, with even a very low output cart. Especially given how low the noise level is with the Ref. The Benz LP-S is rated at .36 mV, which isn’t as low as many. Everything will depend on the rest of your system’s gain, speaker efficiency and your preferred SPLs.
You have plenty of gain for the Benz LPS. I use a Benz LPS with my ARC Reference Phono 3 with no gain issues.
Doesn’t the REF 3 already employ an SUT when running through their MC input. I think at times it’s overlooked, but most tube phono stages have built in SUT’s. Manley, Aesthetix, and as all who frequent A-gon know, Atma-Sphere, do not use an SUT. IME, 68 db should drive a .3mv Benz. Not an easy task for a tube stage without an SUT, but 68db should work, pending it's quiet enough for you. I drove a  Benz Ruby 3 with a Lamm LP2, and the 57.5 db gain was not quite enough.... Cheers -Don
The ARC Reference Phono 3, like the Reference Phono 2, has a FET front end instead of a SUT. Mine has plenty of gain to run a Benz LPS into an Aesthetix Calypso.
The LPS is not really a great candidate for an SUT because of its 38-ohm internal resistance (DCR). At .36 mV, you’d likely want to use a 1:15 SUT, which would present an impedance of 209 ohms to the cartridge. That’s pretty low, when you think rule of thumb is 10-25 x DCR (I prefer 25x usually). 1:10 would create a better impedance match at 470 ohms but the gain might be sub-optimal.

I have an older Ebony L at .26 mV and DCR of 3.5 and I use an SUT of 1:20. It sounds good but the loading is a touch high at 118 to the cartridge, accentuating the top a bit. The newer Ebony L has a DCR of 5, which is better for 1:20.

The only Benz that is a truly great match for an SUT is the Ebony TR, which is designed for use with one. With a DCR of 1 ohm and output of 0.1 mV, it should be pretty ideal for an SUT of 1:40.

Thank you for your insight. It is very valuable. My question was not so much about there being enough gain but would the addition of a SUT improve the end to end performance of my set-up and wrm57 indicates that it wont.

I'll report back when it arrives to comment on the end to end performance.   
don't sully yr ref2 with a sut !
it should have more than enough gain for the benz.
keeping the signal path simple will give you the best sound.
I agree with audio_d.  Why add a component, along with ICs and connectors, in the signal path of a cartridge with a very low output voltage, when that is completely unnecessary?  But should you insist upon doing it, you would run the output from the SUT into the MM or low phono gain inputs of your ARC phono stage, assuming it has provision for high output cartridges.  In other words, if you use a SUT, you treat the LOMC cartridge as if it was an HOMM type.  Thus, you would bypass the FET gain stage that others have mentioned.  Not only do you not need to use a SUT, but also if you do insert a SUT, then you need to concern yourself with the quality of the SUT itself, a whole new can of worms.  Not all SUTs sound alike, let alone "good".  Furthermore, the high-ish internal resistance of the Benz is another good reason not to do this, or at least not to assume you will like what you hear.  Highs will likely be rolled off due to the impedance mismatch, which is not a coloration you want to impose on a Benz.


As a bit of a simplification a MC phono stage does two things.  First there is some gain, and secondly there is equalisation  - usually RIAA.  That first step can be done
  1. On the cartridge (High Output Moving Coil);
  2. Electrically - MC Phono Stage
  3. Externally via a Head Amp
  4. Externally via a Step Up Transformer.

This latter option is not adding a component.  Yes you see another box but the Transformer is a passive device (the actual key to why they are so effective, by the way).  If anything it is subtracting a component as you bypass electronic circuitry.  Other things being equal and the Transformer is well done it is the perfect solution.  

Other things are not equal and the downsides to an SUT are that they are susceptible to noise if placed too close to other components such as power supplies.  They are expensive, the good ones anyway.  Also there is the issue of impedance matching.  If the quality of your Phono Stage is good, and I guess that includes ARC, then I would not bother.  On the other hand I have read in other forums of of good results with Step Ups into other high quality phono stages.  One of the best resources out there is by Andrew Rothwell


andrei, I have to disagree with your statement that adding a SUT is not equivalent to adding another component, although you do make a good point that phono stages with enough gain for a low output MC usually use an internal gain stage to boost the output of the MC, which in effect is ALSO an added component.  (However, many phono stages with hi gain achieve high gain by the choice of the gain device [tube or transistor] used in the input voltage amplifier.  MM phono stages also add gain of necessity.  So sometimes it's just a matter of designing the amplification stage to suit one class of cartridges or the other.)  SUTs are not flawless, and adding a SUT also requires adding an additional pair of Interconnects and at least a pair of connectors in the signal path.  You might say that a SUT adds a different kind of problem, as compared to using a high gain tube or transistor to boost the low voltage signal of an LOMC.  Anyway, we agree that the OP does not need a SUT. Nor does he need a new phono stage.

gtaphile, FWIW, I'm using an ARC Ref 2SE with a Lyra Skala cartridge (0.5mv) and while there is enough gain using the high gain setting, I am much happier since I've added an Ortofon Verto SUT.   With the SUT, the dynamics, detail and headroom are immense compared to the sound without the SUT.   Also, without the SUT in the system, I could never hear any difference by changing the load.  Now there are significant differences by varying the load.  Just my 2 cents.  
I agree with taxmandme, my phone stage is a Conrad Johnson TEA2MAX, which has 55 db of gain.  This is a very high quality tube phono stage.  Although it can handle a range of cartridges from 0.3 mV to 5.0 mV, for any of my low output MC cartridges it is much better to use my recently acquired Bob's Devices Sky 10, set for 5:1 step up.  Much better.  There is a sense of ease about it, greater dynamic range especially noticeable during the quieter passages of performance.  As others have pointed out adding an SUT requires compromise.  In addition to the SUT, a very good set of interconnects is essential, so this is not a trivial tweek.
Dear @taxmandme : """  Also, without the SUT in the system, I could never hear any difference by changing the load. """

That only confirm that LOMC cartridge are " non-sensitive " to impedance load changes and confirm that in this regards your AR design is a good one.
What happens when you introduce a SUT in your hybrid PS is that exist a reaction inside the PS circuit wi9th impedance/inductance and capacitance and this is a real problem and not desired for the cartridge can shows it at its best.

Good SUTs sounds good but has its own limitations on noise and distortion levels and of course limited frequency range with out deviations where a good bipolar full SS phono stage can outperform your today set up.

Regards and enjoy the MUSIC not DISTORTIONS,

There is only one problem with your analysis: "the bipolar full SS phono stage" that sounds better than even a mid-level tube phono stage is unobtainium.  Nice try though.
So we now have many posts quoting the science and others quoting user experience indicating that a quality SUT and cables may in fact improve the end to end performance of a high quality and capable PS even if they have sufficient gain required for LOMCs.
I am still waiting for my cartridge to come in and I will listen carefully for any anomalies even though one might not know what is missing until you try a SUT in the chain.  
Dear @billstevenson : Well, that kind of designs exist in the market. I'm using one for some years now and outperforms not mid-level tube designs but any one .

@gtaphile :   "" not know what is missing until you try a SUT in the chain.  "

for " thousands " of years I used SUTs with either: tube and SS designs. I owned almost every SUT in the market. In those time I really did not know nothing of what " today " I learned/experienced on the SUT subject.
As a fact I still own Denon, Entré and Audiocraft SUTs. I still use it time to time, so I have past and today first hand experiences.

I can tell you that you can't miss anything through the SUT experiences against a today good active design using today bipolar devices. A SUT can't compete in anyway against today bipolar transistor. The audio signal is degraded at higher levels through a SUT than a transistor. Problem is that the audio signal in your system pass through tubes in the AR item.

Audiophiles have different kind of experiences and learn different " things " and sometimes exist misunderstood in what we learned.

Regards and enjoy the MUSIC not DISTORTIONS,


Please provide facts to back up your claims.  What phono stage are you referring to?  What tube phono stages have you compared it with?  What is your criteria for deciding what phono stage "outperforms" others?  Try and stick to facts.  Making a statement that you have used something for "thousands" of years, does not help your credibility. 

I will state for the record that I have personally listened to high end phono stages from Conrad Johnson, Audio Research and Manley that sound better to me, in my system, than a solid state phono stage that I have compared them with.  My solid state reference has been a Lehmann Silver Cube.
Dear @billstevenson : No problem because exist several facts about but before that is important that you and me talk in the same " audio language ".

All the audio items are designed to accomplish specific targets and I would like that you share from your point of view which of those item targets are the main ones in a phono stage .?

Could you, please?

Thank's in advance.

Regards and enjoy the MUSIC not DISTORTIONS,
Raul and I are more often than not on opposite sides of controversies like this one.  However, in this case, we are on the same page. On the other hand, I could well imagine that a tube phono stage with marginal gain when matched to a particular LOMC cartridge would sound better if a SUT is interposed between the two. That's no surprise to me, either.  So, this could also be a case where both sides are "right", because no one has defined the terms of the argument. How low does the output of the cartridge have to be in relation to the gain of the phono stage before noise and reduced dynamics become obtrusive, whereupon things get better if you add a SUT?  To some degree, that is a subjective judgement, unless we are talking about ridiculous mismatches.  However, in my opinion, the particular example posed by the OP should not benefit much from adding a SUT.

I use a bipolar transistor input stage at the front end of an otherwise all-tube phono stage. Raul doesn't like this, because it uses mostly tubes, but the tremendous gain afforded by the transistor does result in an easy, dynamic, unstrained, and very low noise (not to say "no noise" that I can perceive) presentation that was not obtainable prior to introduction of the solid state input device.  In fact, there is no LOMC that my preamp cannot handle with ease, up to and including an Ortofon MC2000 with an output of 0.05 mV.  But again, this is my subjective opinion.


Answering my questions with your own questions is a polemic exercise.  If we are to have a meaningful conversation this is not the way to start.  I provided a frame of reference that offers a clear starting point.  Please answer my questions.
Dear @billstevenson : For to persons can have a dialogue in a subject the first premise is that both understand the subject under dialogue/discussion. That's why I posted:

"""   before that is important that you and me talk in the same " audio language ".  """

It's useles that you, me or any one give answers or make questions when one gentleman is talking of " oranges " and the other of " airplanes ".

So,  from your point of view which targets are the main ones in a phono stage .? what are we looking for in a phono stage?

You can be sure I have answers to your questions, no doubt about. 

Regards and enjoy the MUSIC not DISTORTIONS,

Since English seems to be a secondary language to you, perhaps you do not understand my point.  If that is so, please look up the word "polemic" and you will at least understand my objection to your approach.  If you already do understand my point, then you will need to seek out a different person to parry with.


This is not an 'polemic'' but well an ''pragmtic point''. Nobody

considered the prices . But assuming that one can get an decent

MM phono-pre for, say, $500 + an decent SUT for also $500

one will get an excelent phono-pre for $1000. No active or

tube phono-pre irrespective of price can compete with such a

combo resonable prices assumed. 

Dear @billstevenson : Parry? to you?. Why should I?

My point is easy: to have a dialogue where you and me speak about " oranges " and only want to be sure about.

All of us have some misunderstood audio subjects because audio is so wider whole subject. Here we are talking of phono stage and I need to know the main targets in a phono stage from you and that's all.

If you refuse to do it could be because: you really don't want my answers on your questions or you are not to sure on my specific question or just you don't want to do it.

The " ball " is in your " field ". Shall we play?

I passed the ball to you with my very open ended and reasonable questions.   There are no trick questions or traps in them.  You are free to answer them or not, and you are free to state any assumptions you wish in your reply.  I do not intend to engage further without the courtesy of your open answers. 
Two words come to mind: distance and irritation
Dear @billstevenson : I never leave a question with out give an answer.

You said: "  your open answers. "

For me, in audio, exist no open answers but many times are very elaborated answers because in audio each link depends of all and each other links in the audio chain.

An open answer as : yes or not or an  item model means nothing with out an explanation of the " open " answer.

The other side is that all audio human beens  understand audio subjects in different way and that's why dialogue/discussion sometimes is useless for every one.

You posted:

 """    My solid state reference has been a Lehmann Silver Cube  """

in the same post with your " open questions " and that tell me that is probable that you and me can talk on different audio subjects.

With all respect to Lehmann and its owners and to you I think you have a very low reference line. I'm not saying is a bad reference only that could be not a real reference to discuss your questions. It's curious that been a phono stage the manufacturer specs did not shows the RIAA deviation level. Why ? could be an interesting question for you and its owners.

SC is a SS design that use in its first gain stage a microphone amp chip and in the second gain stage another chip by BB and and an output buffer with FETs. Lehmann had its own way of thinking about. I never heard it in my system but through different system.

When I talk about SS phonolinepreamp SS designs certainly I'm refereing to a different kind of designs/performance where my only reference is live music.

Regards and enjoy the MUSIC not DISTORTIONS,

Thank you for your answer although I must confess that it is not entirely clear to me what you are saying in all particulars. So I will not respond to the parts where I do not fully comprehend your answer. We can agree that everyone of us has unique experiences and that it is difficult to share points of view based on different experiences, references, environments and so on. Nevertheless it can be worthwhile to discuss matters of mutual interest even if our diverse backgrounds prevent full accord. So, I don't agree that it is useless to try.

Although I am an engineer, I am not an electrical engineer and am not qualified to discuss circuit designs or the relative merits of same. I think we can agree that faithfulness to a spcification such as, but not limited to, the RIAA equalization curve would be sine qua non to achieving reasonable sound reproduction. You argue to strive for reproduced sound that is comparable to live music. Although we can agree that this is a noble goal, I suspect we differ on weather it is possible to do so in any practical sense. This is an interesting subject, but far removed from the subject of phono preamps. Nevertheless, since you raise the point, let me comment briefly.

The difficulty is the acoustic environment that a reproduction system is called upon to operate in. It is not and cannot be identical with the one where the recording was made, unless both the live and the recorded result are both listened to in the same space. Although that can be done and has been done, it is not what most of us do in our recorded music lives. As such, it is better to acquiesce to the reality that for most music reproduction the playback environment will be different from the original performance environment. That fact makes using the standard of live performance less practical than perhaps we would wish it to be in an ideal sense. In it's place we substitute various components and compare one vs. the other. Not ideal, but that is what we do, or at least that is what I do. With that said, in my listening room I have a piano and a set of drums and a lot of hand percussion instruments. So I do try to seek the holy grail, but alas my piano sounds different from an identical one played elsewhere, and even something as simple as a triangle or a ride cymbal sounds quite different in my home as compared to that same triangle or cymbal played out in performance. Too, a piano sounds different if heard at the instrument playing it on stage vs. hearing it played by someone else while standing anywhere out in the audience section. Cymbals, triangles, snare drums and on and on all sound different at various locations because of the reflections, reverberations, and so on imposed by the environment.

So, back to phono stages. I listen to music that I am familiar with; first with one phono stage, and then with the other. Most of the time, using good recordings, it is possible to hear a difference. Usually I prefer one over the other. And usually I prefer the sound of tubes although noise can intrude. This is never more true than with LOMC cartridges, even very expensive ones. And when this noise intrudes I have found that a good step-up transformer is the best solution. Now, I think the conversation is back where we began. I like green, you like yellow. Is the conversation useless?
Dear @billstevenson : No it's not. For the contrary it's a good music/audio conversation.

@lewm posted: "  Raul and I are more often than not on opposite sides of controversies like this one . " and you posted:

"  it can be worthwhile to discuss matters of mutual interest even if our diverse backgrounds prevent full accord .... "

I think that mature audiophiles as us in reality are more in agreements than against each to other even when we do not have a full accord. As a fact what makes  an audio conversation a good one is precesily when exist no full accord because it's when the different " sides " of the whole conversation works as a lesson for any one of us and is the only way to grow up. Obviously that the people involved in that conversation must have the attitude to always learn.
Some times in a hot audio conversation and when I think that the other gentleman has no " reason " on the subject time latter ( days, months or even years after. ) I take in count that that gentleman was rigth and me wrong.

we can agree that faithfulness to a spcification such as, but not limited to, the RIAA equalization curve would be sine qua non to achieving reasonable sound reproduction """

not only agree but for me this is the first target and characteristic between a preamplifier/headamp or the like and a phono stage where when we read or some one talks about phono stage the name really comes because that audio item has the inverse RIAA eq. and not because its gain level or something else.

You mentioned the second and third targets in a phono stage where both depends in between: gain/amp levels and noise levels.
So we are talking the same audio language, good.

 You argue to strive for reproduced sound that is comparable to live music "

well, I said that my reference as your is live MUSIC. What means that reference for me?  to know in precise way how and which is the kind of sound that produce the normal music instruments and to know it not only in different kind of enviroments ( orchestra halls, open stages, amplified or not, etc, etc. ) but at near field too with single instruments or blended..

I agree in your comments about and could add that even two same Steinway piano models in the same venue sounds different because can be that have different build material chords ( vintage. ) or something with the piano differences in the build wood or paint and the like. Exist no two same year Stradivarious with exactly the same sound.
Again, in agree that is imposible to mimic live MUSIC through a home audio system.

Now, I posted several times that my audio system main target is to be truer to the recording or at least nearest to.

For my effort trying to approach and have success in that target I need that at every single link in the audio system chain be faithfulness developing the lowest every kind of distortions ( obviously each audio link item must be a good design and with excellent quality design execution. ).

With those premises in mind and knowing in deep both technologies: tubes and SS, by first hand whole experiences I decided to left behind the tube alternative because can't fulfill my main system target. I's just imposible to do it for the tube alternative. As any alterative tubes has trade-offs but against the target are severe trade-offs insuperable limitations to achieve the  targets where SS is way nearer to acomplish it.

I don't listen MUSIC in my system only because I'm a MUSIC lover and I just like it. NO I like to listen MUSIC in my system the way SHOULD be and this " SHOULD be " means truer/nearest to the recording. This is way different to listen only because I like it what I hear even if is wrong.

We are in agreement of the critical importance role of the inverse RIAA eq in a phono stage and to be truer to the recording this inverse phono stage RIAA eq. MUST MIMIC the RIAA curve ( inverse. ) used during the recording.

What means " mimic ": exactly that, with no frequency deviations in between. Well, because its inherent tube limitations this alternative can't fulfill that premise and the SS alternative can do it in a nearest way. Yes, accuracy is always the name of the game here. Ideal could be: cero tolerance that per sé is imposible to achieve.

Of course that I'm using full SS electronics. I don't want to talk in deep about my system but only to give you a precise example where tubes can't do it and my phonolinepreamp does:


that kind of performance is near " perfect " ( nothing is. ) not only because the frequency deviation levels are lower than 0.015db ! but because both channels performs almost exactly.
Btw, you can check through Stereophile electronics measurements ( every kind of. ) and always both channels ( every kind of audio item. ) measures different, way different!

Well, that's me about MUSIC and audio.

Thank's for your answer.

Regards and enjoy the MUSIC not distortions,