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

Discussion in 'Audio Hardware' started by Benzion, Jan 30, 2018.

  1. Warren Jarrett

    Warren Jarrett Audio Note (UK) dealer in SoCal/LA-OC

    Location:
    Fullerton, CA
    For me it is VERY fun to compare SUTs and find one that sounds the best. They each sound very different, so it's an easy comparison. Right?

    I wish you could hear a Music First Audio or Audio Note S4 or above -- not to buy, just to hear. Both are really stunning.
     
    Last edited: Jan 31, 2018
  2. blakep

    blakep Forum Resident

    I've been running current mode/balanced for 10 years now and it would be very difficult for me to consider more conventional phono preamplification now.

    But it is probably a pretty tough sell with most audiophiles-it is, at the same time, too tweaky (balanced tonearm lead) and not tweaky enough being plug and play with the the short circuit and lack of ability to mess around with loading.

    Once you hear it, though, if it is properly implemented, it is difficult to go back, especially if your entry price is reasonable; say under $2000.

    Did you build your stage?
     
  3. Benzion

    Benzion "Cogito, ergo sum" Forum Resident Thread Starter

    Location:
    Brooklyn, NY
    Chances are, it will work well with all cartridges that have similar gain and internal impedance as 103R.
     
    JackG likes this.
  4. John Moschella

    John Moschella Forum Resident

    Location:
    Christiansburg, VA
    What technical problems? You take the 47k out and put a bigger resistor in.

    I think gain should be the primary driver of a SUT decision (that and quality of wire), you can always fiddle with resistors to get the loading you want.
     
  5. Warren Jarrett

    Warren Jarrett Audio Note (UK) dealer in SoCal/LA-OC

    Location:
    Fullerton, CA
    With any SUT designed for MC application, you can change the 47k secondary winding load resistor to a lower value, but not a higher value. Don't take my word for it, ask any transformer expert.

    Any transformer (not only for a MC SUT application) is designed with a ratio of windings, and also for specific operating impedances within a specific frequency range. Audio transformers are linear within 20 Hz to 20 kHz only at their design input and output impedances. When a step up transformer's output is loaded at higher than design, it easily "rings", meaning its linearity goes nuts. When lower, the frequency extremes roll-off at a narrower bandwidth, but not severely within reasonable limits. There is a limit to how much that 47000 ohms can be lowered too, before it does start affecting frequency response audibly.

    All transformers perform exactly as designed ONLY at the design impedances of associated electronics. So, no, you cannot "always fiddle with resistors to get the loading you want", unless you don't care how linear the transformers operate.

    Step up ratio must be right for the impedance of the cart and the impedance of the preamp, to sound as designed. But differences in gain has a latitude, not so critically "right", depending on the dynamic range of associated electronics (expressed as S/N and overload in audio). Thus the preamp volume control is the user's interface to access this latitude.
     
    Last edited: Jan 31, 2018
  6. Baaronj

    Baaronj Well-Known Member

    Location:
    Tallahassee, FL
    Sent you a PM.
     
  7. Baaronj

    Baaronj Well-Known Member

    Location:
    Tallahassee, FL
    I've been using Harmon Kardon XT-3 transformers with my DL-103 for the past few months with great results.

    The XT-3's have 500 and 600 ohm primaries with a center tap and a 50kohm secondary.

    FWIW, the XT-3s replaced the ProJect Tube Box DS I was using previously.
     
  8. Just Walking

    Just Walking Forum Resident

    Location:
    Abingdon UK
    Yes I did. It was quite an act of faith, because it was not cheap to build by any stretch. The design was a collaboration between Erno Borbely and Sigurd Ruschovski. Paralleled complementary JFET input stage, and high current drive into passive RIAA. Then a second gain stage with high current output stage. Times two for balanced for each channel. And shunt regulators, times four - one for each board. And an outboard mains power supply. There are also boards to bal to unbal, or unbal to bal conversion. Same configuration as the second gain stage.

    It can be switch configured to zero feedback over the first stage with an input R of 2 ohms (effectively a short circuit for a 40-ohm DL103), or with feedback to drop the input R to milliohms for low resistance cartridges. It can be switch configured to be fully balanced throughout, balanced in and single ended out, single ended in and single ended out, or single ended in and balanced out. DIP switches on the boards select gain levels for different cartridges.

    I have not added up the total, but the circuit boards, plus parts plus hardware must have come to well over UKP1000. All in all there are over 500 resistors (all Dale RN55D), 360 capacitors (all to do with power supplies, and local discrete regulators - none at all in the signal path), and over 300 semiconductors. It is totally and utterly insane. Each of the boards was individually tested first - that in itself took a while given the number of boards. And once totally assembled, it worked first time, no hum at all and quiet as the grave. And sounds stunning. Six months in and I have not felt the need to take the lids off and fiddle with anything. I would have to if I changed cartridge, though.

    And you don't need to do anything at all with the arm or connector. You have two wires from L and R from the cartridge and (usually) a 5-pin DIN arm connector - so you inherently have a balanced connection with no fuss whatever. Four pins take the signals and one pin is the arm ground. So two screened cables (I use Cardas, wired as star quad), with the screens commoned to the arm ground. Other end of each into an XLR plug.

    Although I have an extensive CD collection, all ripped to a NAS drive, and Tidal HiFi streaming I spend most of my time listening to vinyl, which says it all really.

    Pass the medication......
     
    Agitater likes this.
  9. Warren Jarrett

    Warren Jarrett Audio Note (UK) dealer in SoCal/LA-OC

    Location:
    Fullerton, CA
    Ahhh, John Moschella, did you read that? "... with a 50kOhm secondary". That is the design spec of these transformers, for the impedance on the output, to provide optimum linearity. Replace the phono preamp's input resistors for a higher value, and you mess with the transformers' design intent, risking non-linearity.
     
  10. Warren Jarrett

    Warren Jarrett Audio Note (UK) dealer in SoCal/LA-OC

    Location:
    Fullerton, CA
    Ok, I was very distracted today, so finally I am ready to tell you your answer. The math is a bit complicated, but the answer is simple.

    For your DL-103R, a good load resistance should be about 140 to 280 Ohms. This range would be provided by any SUT of ratio between 1:13 and 1:18. Your Bob's 1:16 is perfect. That is your "Low" setting, provided by Bob, giving you 184 Ohms.

    For a DL-103, a good load resistance should be about 400 to 800 Ohms. This range would be provided by any SUT of ratio between 1:7 and 1:11. Any 1:10 SUT would be perfect for this cartridge, giving you 470 Ohms. But this is not one of your choices, currently provided by your Bob's selector switch. So you cannot use your current Bob's for a DL-103, as currently configured. But, with a very easy modification, which Bob can do, you will be in luck.

    The Cinemag 3440A transformers actually have a choice of 3 primary windings, for 3 different possible step-up ratios. The manufacturer specifies the three choices as "37.5 Ohms", "150 Ohms", and "600 Ohms". These provide 1:30, 1:16 and 1:8 step-up ratios respectively. When your phono preamp has a 47000 Ohm input impedance, the actual load on the cartridge would be 52 Ohms, 184 Ohms, and 734 Ohms respectively.

    734 Ohms, from the "600 Ohm" primary is just right, if you can live with a 1:8 step-up ratio, which I am quite sure you can. Your volume control will be higher than before, and your S/N will be a tiny bit poorer (not enough to matter), but the sound quality of the SUT itself will be better than either of the two settings now provided by Bob. Not everyone will agree, and I already know Bob will not agree, but I am a dealer for SUTs, and previously (for 30 years) a Professional Engineer. I have heard this many times, with my so-called "Golden Ears": lower step-up ratios always provide better audiophile quality of sound.

    I suggest you send the Bob's Devices back to him, and ask him to customize it. Remove the presently wired "High" connection, inside, and re-wire it with the Cinemag's "600 Ohm" primary winding geometry. If he talks you out of it, which he will try, because he thinks 1:8 is an impractical ratio, I would be happy to do it, for the same price he would. He knows me, Warren Jarrett. He knows I am smart and capable, and that we disagree about a few fine points. On the other hand, I helped him make his early SUTs just a little nicer, so he knows that I know what I am doing.

    Probably, if you tell him I am willing to do the work for the same price he would, he will do it for you.

    Your other option is to leave the Bob's SUT alone, and buy a 1:10 SUT, which is quite a common type. The difference between 1:8 and 1:10 is almost insignificant, audibly, so if anyone tells you 1:8 won't work well, but a 1:10 will, they are not being reasonable. A 1:8 will have a bit more open-ness in the extreme high frequencies, and be a bit more dynamic (lively) overall, than a 1:10. Your volume control will be set a bit higher, which means you may hear a bit more preamp noise, when no music is playing, but it will be a subtle difference, and well worth enjoying the even better audiophile qualities of these transformers that you will hear, compared to the "Low" setting you use now.
     
    Last edited: Feb 1, 2018
    blakep, JackG, Rolltide and 2 others like this.
  11. blakep

    blakep Forum Resident

    Medication indeed. Very impressive. Sounds like it it would be a fabulous, end of the line phono stage.

    I envy guys with your ability.
     
  12. Rolltide

    Rolltide Forum Resident

    Location:
    Vallejo, CA
    I have Bob's 1:20/1:40 selectable SUT. He suggests Denons use the 1:40 setting, despite the sort of mathematical apostasy that represents. I feel he's correct on this, with the critical caveat that my Leben RS-30EQ has a gain of only 23.5dB so everything sounds better on 1:40 :). It is interesting though - SUT pairing seems totally qualitative, but you hear of exceptions from time to time. For instance, if I'm recalling correctly Art Dudley runs his 1.05mv TST-15 into a Shindo SUT designed for SPU's. That seems like it would produce hot garbage, but I trust the guy.

    Bob is a good dude. When his new Sky 40 SUT came out, I asked him if I should upgrade to it and was prepared to do so, and he told me to save my money because the difference wouldn't be worth it. You have to love folks like this in the business who sort of put the hobby above their profits.
     
  13. Warren Jarrett

    Warren Jarrett Audio Note (UK) dealer in SoCal/LA-OC

    Location:
    Fullerton, CA
    I see Bob once or twice a year at audio shows, and like him very much.

    But, wait a second, which Denon are you using with 1:40, that you like better than with 1:20? And, since it is so easy to flick the switch, what differences do you hear between these two settings?

    A 1:40 SUT is usually best for cartridges with about 3 Ohm coils; a 1:20 for cartridges with 6 to 12 Ohm coils. I suspect that even though the 1:40 provides more "gain", it actually is no louder for you than the 1:20. If true, that is because you are losing signal in the transformer winding itself, due to impedance mismatch. But if indeed the 1:40 is louder, then there is no mismatch, and I can understand that the 1:40 is sounding better with that cartridge.
     
    Last edited: Feb 1, 2018
  14. Rolltide

    Rolltide Forum Resident

    Location:
    Vallejo, CA
    My Denon is a Zu 103R with a Soundsmith eliptical stylus. I'm going from memory as I haven't had that cartridge mounted in almost a year, but I don't recall the difference being as dramatic as it is with some cartridges. I think it was more about texture and weight then gain.

    The low gan Leben throws off a lot of things as well. I used to think I was a heathen for preferring my .04mv Koetsu with 1:40 vs. the "correct" setting of 1:20. Then I realized that when you take the Leben's gain into account, 1:40 is indeed the right setting. However, when I switch to the Oto's (presumably) more traditional gain setting, 1:20 is normal and 1:40 is a tad bloated.
     
    googlymoogly likes this.
  15. JackG

    JackG Forum Resident

    Location:
    NJ
    Warren - I really appreciate you taking the time to pass along your knowledge! As a follow-up, given your experience with Denon carts, would you suggest the 103 with modded SUT or sticking with another 103R and my current SUT? I will say, in my years using the 103r, I was never less than very happy with it, but I'm wondering if the grass is greener, richer, etc. I'm using my backup DL-160 now but it just isn't the same.
     
  16. Warren Jarrett

    Warren Jarrett Audio Note (UK) dealer in SoCal/LA-OC

    Location:
    Fullerton, CA
    Sorry Jack, I cannot answer this question. I have never heard a 103 or a 103R. I don't know how they sound different, and which is "better". I am a fan of some older Denons: the 103D, 103M and 305. Personally, I recommend one of these. But they are only available used now, and cost at least $400 for an excellent one.

    I could only answer in general, based on a consensus of other listeners who have heard both. Please, anyone reading, tell us how these two cartridges sound different, and if one is generally considered better than the other.

    I know that the 103R is a technically superior cartridge. But, from comments I have heard, people seem to really like both... and, actually the 103 seems to have a bigger following than the 103R. So, I have no idea, myself.

    My advice, Jack, is to stick with the overall winner, by consensus, and either mod or keep the SUT for that choice. If you do mod the SUT, it will be usable with both cartridges. So, then please listen to both and tell us what differences you hear.
     
    Last edited: Feb 1, 2018
    JackG likes this.
  17. Joe Spivey

    Joe Spivey Your friendly neighborhood Spivey-Man

    Location:
    Chicago, IL
    When I was deciding between the 103 and 103R, I was informed they are variations but neither particular one is superior. The 103R was described as having a bit more treble presence. So you could look at the decision as if you want to change tonality. I think since you are happy AND you have a SUT that pairs better with the 103R, I'd stick with it. All this said, I've never heard the 103R...
     
  18. Erocka2000

    Erocka2000 Forum Resident

    Location:
    Brooklyn, NY, USA
    Yes, the 103R is supposed to have a little more sparkle up top and maybe a bit more resolution, but the magic is really in the mid-range of the standard 103. If you are a mid-range magic fan, I'd say get the standard.
     
    googlymoogly likes this.
  19. googlymoogly

    googlymoogly Forum Resident

    We're coming down to personal and listening preferences when it comes to the difference between a 103 and a 103R. The significance really, IMO, is one of emphasis, with the 103R having a tonal balance that somewhat favors the treble end (they both have the same frequency responses, per Denon).
     
    Baaronj likes this.
  20. dividebytube

    dividebytube Forum Resident

    Location:
    Grand Rapids, MI
    JackG and googlymoogly like this.
  21. Just Walking

    Just Walking Forum Resident

    Location:
    Abingdon UK
    Although I have a Zu/DL103, one thing to bear in mind if you are a dyed in the wool purist is that, because of its 40-ohm coil resistance, the noise of the cartridge itself is the limiting factor in the signal to noise ratio.

    The Johnson noise from a 40 ohm resistor in 20kHz bandwidth is 0.11uV. Since the cartridge is nominally 300uV at 5cm/sec, the inherent signal to noise ratio is -68dB. That means that it is the dominant noise source as compared with many phono stages, and comparable to the noise from a really high quality vinyl pressing.

    That said I don't find the noise from the cartridge resistance troublesome at normal listening distance and fairly hefty volume levels.

    However, because the DL103R has 14 ohm coils, the inherent signal to noise ratio is -73dB, a very useful 5dB quieter than the standard DL103. Worth bearing in mind if this is a factor that worries you in the dark watches of the night.

    None of those signal to noise numbers take into account RIAA correction (which tends to improve signal to noise ratio by about 3dB typically), or any noise weighting (another 3dB improvement for A-weighting, which is why some manufacturers quote that), or the effect of 1/f noise from the phono stage.
     
    Agitater and googlymoogly like this.
  22. Baaronj

    Baaronj Well-Known Member

    Location:
    Tallahassee, FL
    To @Erocka2000 's point, I was on the Zu website the other day and noticed they've updated their copy regarding the 103R. Seems they now all but recommend folks go the 103 route unless they need additional treble energy. I imagine this is also because their mod addresses some of the stock 103s shortcomings with regard to resolution. Just a guess.

    FWIW, I got bored and nuded my DL-103 a while back and affixed it to a heavy copper Rega-head shaped shim. Got noticeably improved resolution and clarity. Maybe slightly tighter midbass, but the gains were mostly above ~800Hz.
     
  23. Baaronj

    Baaronj Well-Known Member

    Location:
    Tallahassee, FL
    Super helfpul info here...I was not aware of this difference between the two carts. I've been waffling on whether to get a Zu 103 or 103R. Good to have another data point.
     
    Last edited: Feb 1, 2018
  24. John Moschella

    John Moschella Forum Resident

    Location:
    Christiansburg, VA
    Oh and on loading, I think whether its critical or not is very cartridge dependent. My Benz has a 10 Ohm coil
    I apologize for my initial uninformed post, you are right.

    In the meantime, I have done some reading and it appears to me that you may be best off not changing the 47k at all. There is actually a good explanation of transformer loading and other considerations with SUTs on the Rothwell website mc step-up transformers explained

    Also on the Bob's Devices website "Bob" also recommends not changing the resistive loading. This is what he says:

    "The deal on impedance is that it is not that important with SUTs. Voltage match is what is critical. Having said that, once you make the voltage match, you should look at the reflected impedance. You normally want it to be about 10-times the internal impedance of the cartridge. Now that is not a hard number, it could be 8-times and be fine, and sometimes 4-times can sound great. The important part is that more headroom is better. A lot depends on the characteristics of the phono preamp. Typically if you have enough headroom with impedance, the natural characteristics of the cartridge will be apparent. So, if you have a "bright" sounding cartridge, you may want to have a lower impedance at the cartridge, but if you have the impedance too low, it may sound muddy and flat.


    I no longer recommend adding resistors. There is considerable controversy over this and there is a lot of discussion elsewhere. The signal is so low coming from the MC cartridge, that is the one place I would not want to waste any signal. I work really hard to ensure that the output of the transformer has as short of a signal path as possible. That is the most critical part of the setup, where you have already reduced the current coming from the cartridge to gain extra voltage."

    I am getting my first SUT shortly, its on the way. So I will try some of these things.

    Any feeling on the capacitive loading? On my phono pre I can choose 0 or 100 pF. If this is important than I can see where length of the interconnect cable can also have a big impact, as there can be appreciable capacitance in the cable.
     
  25. Benzion

    Benzion "Cogito, ergo sum" Forum Resident Thread Starter

    Location:
    Brooklyn, NY
    The choice between 103 and 103R was an easy one for me - I never like treble emphasis. It's a suave way of saying "bright", I think. I regularly like things neutral, or a bit on the warm side.

    Anyways, I recently took a frequency hearing test, turns out my hearing starts to diminish by about 12.5 kHz, and is completely history by 14 kHz. I need "treble emphasis" like I need salmon scales for my bagel, instead of lox...
     
    Agitater and Seafinch like this.

Share This Page