To SUT or not to SUT with a Denon DL-103?

I just use a High Output moving coil cart, and don't worry about a SUT.

 

Good for you, simpler that way. But low output MCs universally can sound better than high output MCs. So again, we choose our own compromises, and then enjoy our music.

I wrote "can" because, obviously, there are some really good higher output carts, and some really lousy low output carts.

 

Yes, the low output carts with a nice SUT are probably better, but I enjoy my Denon DL-110. Very musical, with a big sound stage.

 

The DL-110 is indeed a good one.

I had one, and liked it better than the Dynavector high outputs I've owned. They were musically boring, small, and analytical in comparison. But I am a Denon cart fan, through-and-through, so they just seem to present the right sonic compromises for my taste.

Then I gave up on ALL high output carts, and have been complicating my life (with pleasure) on lowest-possible output MCs ever since. Now I like the 0.10 mV ones best, such as from Audio Note, Benz Micro, and Ortofon. It's a hobby!

 

Yeah, on my second one now. But may go for one of the new AT (MM) series this summer.

 

Actually, some SUTs certainly do have multiple gain switches, e.g., models from Bob’s Devices and a couple of other makers.

Not sure what you mean by a 1:20 SUT creating a 120 ohm load. SUTs have nothing to do with impedance generally or with resistance specifically. The ratio of a SUT expresses the effect of the windings on its transformer which create the step-up voltage (gain). The stepped-up voltage is then provided by the SUT to a good MM phono preamp that has cartridge loading switches.

The clear advantage when using a SUT with any low output MC or MI cartridge is that the SUT is an entirely passive device. It’s just a step-up transformer. No power supply or the associated electronics = zero noise to gain up the low voltage provided by an MC cartridge.

 

Yes, but (as you know) the windings ratio also transforms the MM preamp's input resistance (usually 47000 ohms) back to a specific load on the cartridge (47000/20/20 = 118 ohms). Now, if you want to change that MM input's resistors, or add resistors in parallel with the cart, that's another story.

Often, I have added parallel resistors, in order to lower the load on a cartridge, keeping the gain nominally unchanged. So a 1:20 SUT can be tweeked to provide less than 118 ohms. But trying to raise the load above 118 ohms (by replacing 47k with some higher resistance) creates other technical problems.

So what did YOU mean, "Not sure what you mean"?

And, just curious, what range did you have in mind for his typo? I suppose 0.2 to 0.25, correct?

 

Maybe you meant 0.2 to 0.35.

So, this suggestion is not going to work, right? Some cartridges in the 0.2 to 0.35 range might have (dcr) 4 Ohm coils, others 40 Ohm coils, or somewhere in between. This impacts the right choice of step-up ratio for best sound.

 

K&K Audio using Lundahl transformers is one. Not a switch but build-up options for gain changes.

K&K Audio | Moving Coil Phono Step-Up Kits

I've been using one on a Zu DL103 for awhile now and love it. I use parallel resistors to lower the load from 470 ohm

 

I agree, in principle. But, to listen first you have to have, i.e. - to buy the gear first. No dealer is going to have ready on hand a combination of all phono's, SUT's, and carts I'm considering, for me to mix/match and critically listen, and then to make my choice by what sounds best. Therefore, in practical terms, first you make the choice of what to buy, and then you listen at home to how it performs. You make the choice based on specs, experience, your knowledge of theory, AND - adherence to a certain school of thought (if there are different ones). For now, gain is more important to me. I have no experience in SUT's so far. I will go with a head amp to appease my desire for gain now, but have decided to purchase a SUT in the very near future, as well, to start gaining that experience. It's a learning curve - I started with MM carts only, then progressed to MC, now head amps, and then will come SUT's. I won't be surprised if I have more than one soon enough. I started with one TT and one cart, now I have five TT's and 13 carts, 3 more carts are in the plans as we speak.

 

Do have these parallel resistors in the cart/SUT junction or the SUT/preamp junction? In other words, SUT inputs or SUT outputs?

And do you use Y connectors, or did you solder-in the resistors somewhere?

 

No. I meant 0.2mv to 0.5mv, a range recommend by some SUT makers (e.g., Bob’s Devices and Bryston among others) for their 1:20 SUT models.

 

I've gone a completely different route with my Zu/DL103. I feed it into a current input phono stage, so it looks into a short circuit. The input circuit measures the current that flows from the cartridge into a short circuit, rather than the more conventional voltage phono stage.

It is actually a design by Erno Borbely, is entirely discrete, has no capacitors in the signal path, passive RIAA, and is fully balanced input and output.

In three 19" 2U cases. Left channel, right channel and power supply.

What does it sound like? Stunning. Certainly not for the faint hearted, though!

 

Yes, now I remember, Bob Sattin recommends step-up ratio based only on the combined output level of cart and step-up to feed our phono stages with his generic optimum mV range. He doesn't consider that S/N and overload specs vary from phono stage to phono stsge. And he doesn't consider that the ohms transformation, through the tranformer's step-up ratio, creates a load on the cartridge. This load is VERY important for how the cartridge sounds.

As a starting point, A 4 ohm cart should be loaded at 40 to 80 ohms, maybe as high as 120, so a 1:20 should be ok. A 6 ohm cart, 60 to 120 (maybe as high as 180) ohms, so a 1:20 is perfect. A 40 ohm cart, 400 to 800 (even up to 1200 might be fine), but NOT the 118 ohms (into a 47k preamp input) that a 1:20 provides.

So my point is that recommending a 1:20 step-up ratio for cartridges of 0.2 to 0.5 mV is extremely generic. But cartridges are not generic, every one is different. It is dead wrong to ignore other factors, mostly a particular cartridge's coil resistance.

Bob is a super nice guy, makes great sounding units and stands behind his workmanship, though.

 

To know what your MC cartridge will "see" as loading, when connected through a SUT, the formula is as follows:

MM loading (most often 47,000 Ohm) divided by square of the SUT's turns ratio. In DL-103's case, if the SUT we're using is 1:10, 10 is the turns ratio, then the formula goes: 47,000 / 10sq = 47,000/100 = 470 Ohm. Then you compare the result with the recommended loading for the cart, based on the cart's internal impedance.

To continue: DL-103's internal impedance is 40 Ohm, in Zu's version it jumps to 45 Ohm, at least my particular unit does. Conventional audiophile wisdom is that loading should be around ten times the cartridge's internal impedance. In my case - 45 x 10 = 450 Ohm. 470 Ohm resulting from using a 1:10 is the closest possible result.

Now, if you use a 1:20 SUT, the result will be 47,000 / 20sq = 47,000 / 400 = 118.5 Ohm - which is pretty far from recommended loading of around 400-450 Ohm. My current phono has a loading of 100 Ohm, and that's probably why I'm not crazy about the sound. The next step is 100o Ohm, 400-500 is simply not an option.

As Warren said, proper loading is extremely important in LOMC carts, thus, choosing a proper SUT becomes essential, and needs to be done with mathematical precision, and knowing what your cart's internal impedance and recommended loading are. SUT's are not all the same, and should be chosen precisely to fit your cart, not just based on brand, price, or specs.

After this discussion, I have my eyes trained on two possibilities with 1:10 ratio so far: a Denon AU-300CL and a Rothwell MCX.

 

Right! I wish more step-up manufacturers made this clear. I sell two brands of very high-end step-ups through my audio dealership, The Audio Home. Two of the 4 or 5 best brands of step-up in the world , and correspondingly expensive, of course. So I need to keep knowledgeble and clear-spoken about this topic.

Keep in mind that the equation only gives you a good starting point and using 10 squared (470 ohms load) for a Denon is about at the lowest end of an actual range. I say the target load is 10x to 20x the coil resistance, possibly even 30x. This means anywhere from a 400 to 800 ohm load.will.sound best, and maybe as high as 1200 ohms.

If you can start at a little higher load impedance than the equation recommends, then resistors can be added to lower it, and adjust sound to personal taste. But you can only lower it from the nominal, you cannot raise it from there.

 

Any one-size-fits-all suggestions?

I have a Dynavector 20X2L and Lehmann Decade phono preamp and a Chinook on the way.

 

They are located in the SUT box and are sockets that can be solder if one chooses.

Zu recommends a load between 100-400 ohm. Where 400 ohm gives slightly looser/fuller bass tone and 100 gives tighter, maybe too damp bass tone. They indicate a 200 to 300 ohm load is typical for the majority. Me personally, I believe I settled around 300 ohm. It was only after careful listening at 470 ohm that I felt the need to lower it.

 

It's not only bass quality to listen for. With a 45 ohm cartridge, any loading below 450 ohms will start to compress liveliness (or dynamcs, if you prefer that word) across the entire frequency spectrum; and roll-off the ultra high frequencies. I think you should try the 470 ohm load again, and listen for these characterstics, compared to the 300 ohms you're now accustomed to, with a variety of music, just to confirm.

100 to 200 ohms just seems absurd to me, unless someone's system is so bright and aggressive, that they need a lot of cartridge damping (electrically) to get it sounding musical.

During the 1980s, it was common to use much lower loading impedances than most of us use today. That's because high frequency aggressiveness was the worst possible audiophile sin, in those days, so people just damped down their cartridge, with no other concern. These days, we value lifelike dynamics more than ever, and with advancements in equipment design are truly getting it. We don't want our cartridge limiting dynamics before the signal even gets to our preamp.

 

Really good suggestion! I've haven't revisited this in awhile. After listening to quite a few resistor options in the past. I'll give it a go when I have a chance to make the change and some time to listen.

 

So, if I know my SUT (older Bob's Devices 3440A) works well with my 103r, and I'm not looking to invest in a new one (prices have gone way up), I should probably stick with another 103r as a replacement cart? The 103 would seem quite different in terms of SUT requirement.

 

Please tell me the coil resistance of the cart you have now, the resistances of your next cartridge purchase options, and the loading options from your step-up (or the step up ratios, or the dB specs). Then I'll be able to answer your question.

 

Thank you, sir, I'll list what I can find. The 103r (current cart) specifies 14 ohms while I'm considering the standard DL-103 @ 40 ohms . From a review (model is older and not on Bob's site any longer) of my SUT: "With LOW Gain, you use the 150 Ohm transformer tap to get 24db (16x) gain and with HIGH gain, you use the 37.5 Ohm transformer tap to get 30dB (30x) gain. "

 

Off topic (still, Denon DL-103 related), please note my search:

I need to find at least 3 or 4 Denon 103 (any version of 103__) stylus guards.

Denon factory will not sell them separately. If anyone has one or more, that I can buy, PLEASE private message me.

 

Now that I have been taken to the woodshed for foolishly purchasing the Auditorium A23 SUT instead of buying the Haufe transformers on the cheap let me point out that I have been through the following SUTs with the Denon DL 103:

Denon AU 320
Bob's Devices
Beyer Dynamics trannies
Ortofon Verto

Then came the A23...to my ears by FAR the best.