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Are Koetsus worth it?

Discussion in 'audio' started by Tim Jones, Jan 30, 2017.

  1. andyr

    andyr Registered User

    Absolutely! And I would say the majority of LOMC users do not hear the best their cart can deliver because they are limited in the loading they can apply. :)

    Absolutely! And the loading they can apply with a SUT is very limited. :)

    Sure, the purpose of the SUT is to multiply the output of the LOMC by the turns ratio. So with a nominally 0.28mV Benz LP, the output becomes 2.8mV with a 1:10 SUT.

    But I suggest it is a complete non-sequitor to say "the loading is far less critical to the sound quality". The issue with a SUT, IMO, is that there is little ability to get the optimal loading for the cart - so you put up with what you can get.

    Sure, if you have a LOMC that really does sound its best at 100 ohms loading ... then with a 47K MM phono stage and a 1:10 SUT, the cart normally sees 470 ohms. But if you put a 12K resistor on the output side of the SUT, this will change the loading seen by the cart to be 96 ohms (47K in parallel with 12K, divided by 100).

    But if you have a Benz LP, for instance, there is no way to get it to be loaded at 3K3 (the value which sounds best to me, anyway) with a SUT - unless you replace the 47K default loading in the MM phono stage to 330K (330K / 100 = 3K3). Which will probably have implications for the sound of the phono stage's 1st gain stage.

    Mmmm, IMO this is a very biased 'white paper' - IMO full of half-truths. :p But I'm sure all SUT devotees think it is on a par with one of Moses' tablets - ie. God's truth. :D

    For instance, on the 1st page:

    1. More importantly, IM distortion tends to be lower in transformers than it is in transistor amplifiers.

    That is an absolutely true statement. But, although I am not an SME in solid-state electronics, my understanding is that IM distortion occurs in Class AB amplifiers - which have a +ve DC rail and a -ve DC rail ... there is none in a single-ended circuit (which has just a +ve DC rail).

    So IM distortion is not an issue with a single-ended, JFET-based headamp, for instance.

    2. Does the cart's tonal balance change with load impedance? It certainly does if the cart is a MM type but LOMCs are much less sensitive to changes in the load impedance.

    That is completely A-about-T, IMO. MM carts are very sensitive to load capacitance ... not so sensitive to load impedance. LOMCs OTOH sound very different at different loadings.


    Andy
     
  2. merlin

    merlin Avatar changed - Town names deemed offensive.

    I was of very similar mind Tim and moved to Lyra. To be fair I'm lucky enough to know Jonathan but the qualities of the Lyra are exactly what I was looking for on the SME. A richness of timbre combined with a passable level of neutrality which made the results of archiving my vinyl more rewarding to listen to on various sources and systems.
     
  3. daytona600

    daytona600 Registered User

    RCM reduces stylus cleaning to once in a blue moon
    anybody using a high end MC like a koestu without a RCM is throwing away hundreds of hours of stylus life
    usually get 2500-3000hrs out of my koetsu over the last 30oyears
    once in a while use a ultrasonix stylus cleaner or a dust buster to clean the stylus
     
  4. andyr

    andyr Registered User

    Absolutely disagree. Using a wet/vac or ultrasonic RCM is a fundamental prerequisite for playing vinyl ... but you should still clean the stylus every side. As well as using a CF brush (on the LP) before and after play,

    As well as suffering record noise that can generally be eliminated with use of a wet/vac or ultrasonic RCM. :p

    Despite having used a Nitty Gritty for over 20 years (and recently swapped to an ultrasonic RCM) I would not take the stylus on my Benz LP beyond 1000 hours (2800 sides).

    I agree an ultrasonic stylus cleaner is a good thing to have. :)

    Andy
     
  5. G T Audio

    G T Audio Trade: Distributor and Manufacturer

    You might not agree Andy but that is what cartridge manufacturers do. I know because I have asked them...

    It is rare that a solid state phono stage is MM only. Therefore the extra gain required for an MC cartridge is normally done activity. It is here that loading is more critical than with a valve/tube phono stage because the only way to load a cartridge (if you have too load) is with a resistor and in 99.99% of phono stages these resistors are cheap and cost about 10pence each. So now you have a very precise coil of wire in the cartridge generator often made from precious metals (silver or gold) and is then connected to a cheap loading resistor which is a disaster from a sonic POV. Often when using a solid state phono stage and a hot cartridge (early Lyra's spring to mind) is where loading helps to tame the higher frequencies to give a more pleasing audible result.

    I have found that when using a good MC cartridge with precious metal coils that matching it to a SUT also with precisely wound coils of wire gives the best sonic result.

    Loading: IMO the last thing you should be doing is to try to load a cartridge which effectively is a way to restrict or limit its performance. A bit like adding weight to a race car to restrict its performance, or running down the road with a rucksack full of bricks on your back. However I understand this is a way of tuning the sound to give the user a more pleasing or desirable result.

    When using a valve or tube phono stage the most important thing is getting the correct amount of gain and good signal to noise performance. This should be No1 on the list and if you must load or try to reduce the cartridges performance then do this by carefully adjusting the input resistor on the secondary side of the SUT. Experiments and careful listening tests done many years ago proved that loading the secondary side of the SUT has very little impact on the performance of the cartridge. There are a couple of cartridges where great care is needed to achieve the best results and these usually have either very low internal impedance or very high internal impedance.
     
  6. andyr

    andyr Registered User

    And I get back to what Mr Lucaschek (Benz) writes in his specs for the LP ... 470 to 47K. IOW - roll your own! :D In fact, Benz's own phono stage offers 47K - so I'm happy to agree that's what he thinks sounds best.

    I myself don't like the sound at 47K - I find the bass is too flabby (although the 'air' around the instruments is wonderful). So I like it much lower.

    Not quite sure what you 're trying to say here? :confused: That the default 47K resistor is typically a 10 pence res ... or the loading reses which modify the 47K default are 10 pence reses?

    Let me give you a simple example which explains where I'm coming from. A guy who had a Benz LP contacted me because:
    * he knew I had one, and
    * he knew I loaded it at 3K3.

    He had a very expensive US tube phono stage (BAT?) which was MM/MC ... but the MC input was courtesy of a 1:10 SUT. So the load shown to the Benz LP was 470 ohms.

    I lent him a headamp which had a 2nd (parallel) pair of input RCAs and a whole stack of 'loaded' plugs - so he could play with loadings. He found - as I had found - that the Benz sounded best at 3K3 (not 470 ohms) ... so he bought a head amp and now uses his phono stage's MM input.

    So, yes, this might well have tamed the Benz LP's "hot higher frequencies" - but it made made it sound much more pleasurable than the sound he was able to achieve using a SUT, with a 470 ohm loading.

    Mmmm, yes, obviously. :p But all we are trying to do is make a cart sound its best by loading it optimally. Which you cannot do with a SUT.

    Or you can do what my friend did - use a headamp which allowed extremely flexible loading to optimise the sound of his cart with the MM input to his phono stage. He got great gain and great signal-to-noise performance and he achieved the best sound from his Benz LP.

    Andy
     
  7. abbydog

    abbydog pfm Member

    If you are referring to the Lukaschek PP-2 I have one and it is - how you say - not a shining example of the breed. In particular, the bottom end is awol with a Benz LP whatever the loading.

    In fact, it rather amuses me that many dealers selling very expensive cartridges who boast about having 57 varieties of turntable have no phono stages of suitable quality to exploit them. Typically you'll find a couple of afterthought transistor examples from the usual suspects and even a PP-2 would be a bonus!
     
  8. Mike Reed

    Mike Reed pfm Member

    All the foregoing is very interesting if slightly technical for me. Interesting because I've just gone from a m/c only s/s phono stage with plug-in loadings to inbuilt valved stages within my pre.

    All three of my cartridges (Proteus 1 ohm imp., K. Urushi 5 ohms and Benz Ebony 5 ohms (?)) changed 'character'. It was much more than a slight improvement in dynamics etc., but it was beneficial on all three.

    The loading positions on the pre. seem to vary with record as well as cart., although the gain is roughly the same. In other words, the loadings (3,6, 12 and 40 ohms) don't seem to correspond with the internal cart. impedances (although I never use 40). I find it baffling after s/s but am more than happy with the transition. The Transfig. and Koetsu have identical output, with the Benz being slightly higher.
     
  9. G T Audio

    G T Audio Trade: Distributor and Manufacturer

    If you look at my first post on this you will see "Published loading figures are based on a "recommendation" from the cartridge manufacturer and is arrived at by listening in the cartridge manufacturers system, using their test electronics and in their listening room. It is done by ear and not by measurements. Obviously their value could be, and often is, very different from what works best in your system".

    The Benz LP and LPS fall into the "high impedance" category I mentioned in my first post. These have high internal impedance at 38ohms so I am not surprised that owners prefer it when a higher load impedance is used. The best performing cartridges normally have an internal impedance of less than 6 ohms.

    What I am saying is the cartridge coils are very precise and intricate and are similar in quality to the transformer windings of an SUT. Basically in a solid stage phono stage cartridge loading is achieved by changing the value of a resister (>47K ohms) that sits directly across the cartridge windings whether in parallel with another resistor or not. To connect an expensive cartridge to a phono stage where a cheap resister is used is very poor IMO as there could be significant audio degradation due to the cheap quality part, something that could have a bigger effect on the sound than changing the loading value itself! The design of the phono stage also has a significant effect of the performance of the cartridge so the whole phono stage including the MC stage, whether head amp or SUT, should be considered as one.

    l'll simply say that there are SUTs and SUTs. Not many audio manufacturers use good SUTs because they are expensive and not many transformer manufacturers know how to make good ones these days. I suspect your example above is more to do with the quality of the SUT used than any loading applied to the cartridge.
     
  10. G T Audio

    G T Audio Trade: Distributor and Manufacturer

    The EAR 912 uses different turns ratios on a pair of internally mounted input step up transformers providing 30, 26, 23, and 20dB of MC gain before the MM phono circuit. The loading switch just selects the different turns ratios i.e. different MC gains and the front panel just shows the associated load presented to the cartridge on that setting. Basically its just a gain switch.
     
  11. Mike Reed

    Mike Reed pfm Member

    Thanks. Sounds as though it's not really a loading (i.e. impedance) switch, then.. However, there's a gain switch as well, starting at zero and reducing by - 6 and -12 dB. The -6 setting is more or less de rigeur for all my cart's regardless of where the loading (called 'adjustment') switch is pointing.

    My Superline stage had capacitance plugs as well, which were needed, but there's no such facility on the 912; presumably because valves or valve circuit designs render capacitance a non-issue. Or because, unlike the Superline, the signal ends up going through a m/m circuit.

    It would have been preferable to have mastered the abacus before investigating higher mathematics but it's a bit late for that; knowledge is never wasted, however !:D

    B.t.w., my Ebony L's internal impedance is 5 ohms, whereas I see that the LPS is the 38 ohms you mentioned above. Seems odd for a manufacturer to have such a discrepancy in their range although the Ebony does have the not insignificantly lower output.
     
  12. andyr

    andyr Registered User

    I agree there are SUTs and SUTs ... but I would think that with the high price of the LAMM phono stage (which is what the guy who changed to headamp+MM input had), they would not be using the cheapest one they could find. :)

    Andy
     
  13. pmac

    pmac lovesrecordplayers

    AFAIK Lamm use Jensen transformers
     
  14. andyr

    andyr Registered User

    So from GT's PoV - these must be cheap rubbish (given that the sound with a properly-loaded Benz LP into the Lamm's MM input is so much better)! :D

    Andy
     
  15. G T Audio

    G T Audio Trade: Distributor and Manufacturer

    :)

    Not so much cheap rubbish, but I doubt Jensen use exotic core materials or oxygen free copper and oxygen free silver in their transformers which is why I wouldn't use them in my high-end designs...
     
  16. G T Audio

    G T Audio Trade: Distributor and Manufacturer

    The -6 and -12dB gain adjustment is made for tailoring the gain of the phono stage to match the gain of your line level inputs.

    I would guess this is omitted in the 912 because very few if any, would use a full function preamp of this quality with a MM cartridge where changing capacitive loading would effect performance. It is much more likely a MC cartridge would be used with the 912 which would not require any capacitive loading.

    What some cartridge manufacturers do in order to make their cartridge generators more efficient, is to use a thinner wire (= less mass) for their coil windings. The result is the moving mass of the generator is lower with the thinner wire used so greater resolution is possible, but the down side is there is a higher impedance due the higher resistivity of the thinner wire.
     
  17. pmac

    pmac lovesrecordplayers

    You say you doubt, so you don't really know then?
     
  18. Jonathan Ribee

    Jonathan Ribee Unavailable at present

    If I had one of these...
    [​IMG]

    I think I'd stop listening the the music, but spend all my time dialling in every single track to ensure the noises that make up the music were absolutely optimised. And I'd need three arms for the different carts, again - selected able on a track by track basis.

    The blurb...

     
  19. montesquieu

    montesquieu pfm Member

    Nah. I picked up an EAR 912, which has a very similar feature list, and to a large extent it's set and forget (I have figured out the best settings for my various cartridges, swapping between the two arms), though I find it sounds best generally at 0 db (no attenuation) .. I only use the -6 if the disc has been recorded too hot.

    Agree with G-T btw, adjustable capacitance is not a thing that's needed on the 912, I've seen it on vintage Japanese kit (before MC became pretty much de rigeur at the high end) but more faff than benefit I would say - no so with the moving coil options.
     
  20. anubisgrau

    anubisgrau pfm Member

    sure, it is well proven decades ago that the MMs (some!) need to fiddle with capacitance. MCs have their own weak spot we all know about:)

    btw, with 912 - how's the quality of the stock step up transformers inside, anyone compared them with anything decent outside? when i had 834P, i hardly used it via MC input, i found stock SUTs average (though sufficient for a certain entry level MCs...)
     

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