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Benz Micro Gullwing SLR: headamp or SUT?

Discussion in 'audio' started by Rosewind, Jul 10, 2019.

  1. Rosewind

    Rosewind Lost in Translation

    In a follow-up review of the Benz Micro Gullwing SLR by Alan Sircom, he mentions that "there has been discussion" (where?) that "the non-iron ruby/neodynium generator" of this cart "is not a fan of transformer-coupled phono stages" (Alan Sircom, "Equipment Review: Benz-Micro SLR Gullwing", Hifi+ 85).

    Another tid-bit from that article states that the solid state phono stage of Benz Micro, Benz Micro PP1 Lukascheck T9, seems to be fixed at a 22K load. Quite a high load for this cart that has an internal impedance of 38ohms - similar to what is required for a Denon 103, by the way.

    A headamp seems to be the way to go with the Gullwing SLR, but a good SUT also works, however, perhaps not to perfection?

    I have a Partridge 977 SUT (6:1) that loads the Gullwing SLR with 1305.6 ohms (47000:36) and gives my Croft Riaa R a little over 2mV to work with. The gain should just be sufficient, but I still have a nagging feeling that the Croft Riaa R would like a little higher gain.

    I have looked at different transformer-based MC Step-up transformers based on Lundahl and Haufe. I know that there are other transformers around, but the transformers all have in common that they cannot dispense with the laws of physics and give the Gullwing SLR both perfect gain (5mV) and provide a perfect load of >400 (going up to 22K or what?).

    6:1 gives 1305.6 and 2.10 mV (2.04mV - after deduction of impedance dampening)
    8:1 gives 734.4 ohms and 2.8 mV (2.66 mV)
    10:1 gives 470 ohms and 3.5 mV (3.24 mV)
    11:1 gives 388.43 ohms and 3.85 mV (3.51 mV)
    12:1 gives 326.4 ohms and 4.20 mV (3.76 mV)
    14:1 gives 239.8 ohms and 4.90 mv (4.23 (mV)
    18:1 gives 145.1 ohms and 6.30 mV (4.99 mV)

    So if I use a SUT, it seems that I am stuck with
    - low gain + perfect load
    - perfect gain + too low load

    Any comments on the technical aspects of this?
     
  2. Arkless Electronics

    Arkless Electronics Trade: Amp design and repairs.

    Just change the input resistors in the Croft to whatever you need for the correct loading.... It would be a bit of a lottery as to what the frequency response would look like but it tends to be anyway to some extent with SUT's... One of the reasons I prefer head amps!

    I wouldn't fret over the input level as there is no real "correct" input level. A valve phono stage will usually have loads of overload margin so even 10mV or more is not an issue, and at the other extreme, hiss and insufficient gain to give the volume you require are the limits on how low you can get away with.
     
  3. Rosewind

    Rosewind Lost in Translation

    Thanks Jez. I am going to test a headamp when funds permit. Perhaps I will even give the Benz phono stage a go if I can get one at a good price. Then I can compare the Croft Riaa R + Partridge SUT with the Benz PP1. In the end, I am interested in how the music sounds, not in how the ewuipment measures.
     
  4. Ali T

    Ali T pfm Member

    I have a Gullwing and have tried a good few SUT’s with it, best to my ears is Tribute. Have tried Hashimoto, AN, Luxman etc.
     
  5. Arkless Electronics

    Arkless Electronics Trade: Amp design and repairs.

    With all hi fi equipment if it measures bad it sounds bad... or weird...(and some like weird!) if it measures good then it may sound good.

    There is no "synergy" or "special matching" between a cartridge and phono stage so don't expect a Benz phono stage to be better with a Benz cart than any other phono stage correctly loaded for the cart...

    With SUT's it's very different. There can be all sorts of frequency response anomalies which can vary with both resistive and capacitive loading...
     
  6. Rosewind

    Rosewind Lost in Translation

    Thanks Ali.
    Did you try "The Head" TX4 by Tim de Paravicini?
    The Tribute is s new entity to me. It will be included in the list of SUTs to pine for.
    Jez.
    If weirdness makes beautiful music, I am all for it. The Benz phono stage: I just want to be able to get it out of the equation.
     
  7. Ali T

    Ali T pfm Member

    No haven’t tried that one. Tribute make some of the best transformers on the planet, sadly Pieter no longer sells to the diy community.
     
  8. DimitryZ

    DimitryZ pfm Member

    I am running a lot of different MCs on my table with universal headshell tonearm. I needed to have an easily accessible way to change input impedance and the phono stage dedicated to that table has those via switches in the back. So I used a pair of dual RCA female to one RCA male (Audioquest), a pair of low impedance cables (Blue Jean) with RCA to spade pigtail adapters and two of these resistor substitution boxes to make a readily accessible loading method:

    https://www.amazon.com/Elenco-RS-50...&sprefix=resistor+substitution,aps,224&sr=8-2

    I was worried that this would hum, but it did not. So a bit inelegant, but definitely works.
     
  9. Rosewind

    Rosewind Lost in Translation

    Still I saw a new one for sale on eBay just now. Out of my reach financially at the moment.
     
  10. daytona600

    daytona600 Registered User

    Rosewind likes this.
  11. G T Audio

    G T Audio Trade: Distributor and Manufacturer

    Trouble is that too many switches and multiple connections at low signal levels will often negate any improvements the gain/loading options will make. Don't forget the signal coming out of an MC cartridge is incredibly small and this can be affected too a much greater extent than a larger signal. Another thing, when using an SUT any loading has very little effect on the sound, unlike a solid-state phono stage with resistor loading. The most important thing when using an SUT is that you have the correct amount of gain for the MC cartridge into the phono stage in order to maximise the signal to noise and also to prevent any overloading of the gain stages within the phono stage.
     
    Last edited: Jul 10, 2019
    Fretbuzz and Rosewind like this.
  12. Rosewind

    Rosewind Lost in Translation

    Thanks Graham.
    A SUT - get the gain right and you are almost set.
    A solid state headamp / phono stage - you must adjust your way to audio nirvana.

    Ali:
    Did you try a headamps as well as SUTs along the way to your preference for the Tribute SUT?

    Daytona:
    I think a unit like that would make my head spin. But if it helps make music sound better, I'm in.
     
  13. G T Audio

    G T Audio Trade: Distributor and Manufacturer

    Correct, this will cover 95% of MC cartridges, although there are a few exceptions. Also preferable to choose an MC cartridge with an internal impedance less than 10ohms, even better is <6 ohms. This will put you in the 95% range where the gain will be matched and the SUT will reflect a suitable load to the cartridge, although the latter is much less important with an SUT.

    With solid-state in most cases, you just get a gain setting (normally MM or MC) and then a series of resistor settings that just apply a resistive "load" directly across each cartridge coil (L & R). On some SS phono stages, you might get several different gain settings, in which case you select the one that gives the best signal to noise but does not overload the input gain stages. Once the correct gain has been selected you can adjust the loading to get the balance of sound that you prefer the sound off. Most just select the one the cartridge manufacturer recommends, but this is dependant on their test set up and system and will be different from your set up and system. Just use their setting as a guide. Loading is normally applied to correct for the rising frequency response inherent in an MC cartridge design, although some cartridges are worse than others in this regard.

    With regard to your Benz Micro Gullwing SLR, and if you were using it with one of my phono stages, I would recommend a 1:10 ratio SUT which would provide a total phono stage gain of 68dB and approximately 470 ohms reflected back to the cartridge.
     
  14. Ali T

    Ali T pfm Member

    Yes, had a Denon HA500, then moved on to the 1000, which I completely rebuilt with new components. Both very good, the 1000 clearly better though. Also had a Firebottle tricked out with Z foil resistors, also very good.

    I find in general you get a more up front sound with a head amp compared to a SUT. Down to taste which you prefer, I found a good SUT was a little more relaxed and organic- seemed to let the music flow a little better, which to my ears I preferred.
     
  15. Rosewind

    Rosewind Lost in Translation

    Thanks for the replies about using a SUT vs a Headamp. It is a matter of personal preference in your own system.

    Of course there is a more radical approach to the SUT / headamp "headache":
    - change cartridge to an MM or MC high Output cartridge.
     
    Last edited: Jul 12, 2019
  16. Mike Reed

    Mike Reed pfm Member

    D'you mean high output m.c, Peter? I'm not sure why you don't use a normal (?) m/c stage with your Benz; either s/s or valved. To my mind, adding an extra connection/amplification unit to microvolts of signal, whether via SUT or expensive head amp, adds complication. I had my Benz LP Ebony through s/s (Superline) and valves (912) and it was superb (esp. through the latter)

    If you had a stone bodied Koetsu or top Lyra or anything in that rarefied territory, then experimentation to get the last ounce of performance might be justified, if, that is, one is an inveterate tweaker, which I'm not. To my mind, accurate cart. set-up is more of a priority here. Just my take, mind !

    Should I simplify my kit due to encroaching age related facility loss, I'd seriously consider a Vitus integrated or similar and would turn to the top ph./stage by E.A.R. or its equal, if there is one. Having my box count dwindle from the Naim proliferation to the current count and increasing s.q. as a result, simplification seems to work for me (I'd keep the ESLs though !:))
     
    Rosewind likes this.
  17. G T Audio

    G T Audio Trade: Distributor and Manufacturer

    It's very straight forward really. Buy yourself a good MC (Ortofon, Dynavecor, Lyra, ZYX etc) that outputs around 0.5mV and use a 1:10 SUT (20dB). Alternatively, if you want to go to something more exotic, choose one that outputs around 0.2mV to 0.3mV and use a 1:20 SUT (26dB) - Job Done. Anything more exotic then seek advice from the cartridge manufacturer/distributor/dealer or an expert who can give proper advice.
     
    Rosewind likes this.
  18. Rosewind

    Rosewind Lost in Translation

    Mike.
    When I sold an EAR 802 and bought the current Herron preamp, I bought the Croft Riaa R to go with the Partridge SUT and the Benz Gullwing. This decision was made on the basis of what money I had available at the time.
     
  19. Arkless Electronics

    Arkless Electronics Trade: Amp design and repairs.

    Almost all valve phono stages with MC input use an SUT internally. Hybrids often don't (FET's instead).
    All valve MC stages without SUT's and valve head amps can be done (I've done it before myself) but are impractical.
     
  20. Rosewind

    Rosewind Lost in Translation

    I intend to see how far the Croft Riaa route will bring me with a SUT/headamp or with an MM cart.

    When I have done this I may very well return to an MC stage. I have owned Ayre P5ex, Perreaux Silhouette sxv1, and Naim Prefix S + preamps with onboard phono stages. Of those I liked the Naim Prefix and the EAR onboard stages the best.

    I like the voicing of my Herron pre with the EAR 516 and Quad ESL 57s, so it is a matter of finding the best vinyl replay on my limited budget now that I can no longer fork out thousands of € or £ in one go.

    This thread has put a few doubts to rest with regard to the loading of cartridges and gain. The rest is a matter of listening and chosing.
     

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