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Croft Phono Integrated - overly bassy phono stage?

Discussion in 'audio' started by Mumdad, Jan 5, 2019.

  1. Dowser

    Dowser Learning to bodge again..

    That was me - even when running Naim pre amps I prefer the DL110 into the MC cards, not the MM. This was not just the volume difference, I preferred the higher frequencies with it feeding MC. I’d advise DL110 owners to try it if they have the option :)

    To note - it works fine into MM, sounds better into MC (or via step up or head amp)...in my opinion
    Rosewind likes this.
  2. Rosewind

    Rosewind Lost in Translation

    I have a Coft Riaa R with a Partridge 977 SUT and that combo sounds absolutely fine - much better than the nice Arcam rPhono I just sold. However it must be said that I just adjusted the height of my Thorens TP 16 tone arm which had been positioned a tad too high for the arm to be perfectly level with the record when playing records. I have a two-piece record platter - a Blue Horizon Record Mat - that enables height adjustment for both 180g and regular vinyl records. That is handy.

    Now playback is just a little darker than through my digital playback chain but just as enjoyable and "right." I use a Benz Micro Gullwing SLR and although the gain of that combo is a little on the low side at 2.04mV, it lets my cartridge meet a 1305 ohm load.

    If the two German magazines, one of which I am a regular reader of, had detected any sound deficiencies in a ddition to their measurements, they would have reported it and the final assessment would have suffered.

    As quite a few people have stated, there must be some mismatch going on in your system. Did you try to contact Glenn Croft about this? Perhaps he would be able to see what is the matter? He has a reputation for being very helpful when it comes to looking after his products.
  3. Arkless Electronics

    Arkless Electronics Trade: Amp design and repairs.

    /\ don't do this! Very bad idea. Frequency response probably well out due to gross loading mismatch and strong possibility of overloading a MC input causing distortion.
  4. Arkless Electronics

    Arkless Electronics Trade: Amp design and repairs.

    If Croft still use the same RIAA network values then the 470K resistor can be replaced by 510K and this should remove the bass boost and presence cut and result in a more accurate RIAA curve. It's unlikely that the very small FR aberrations would be audible anyway though, but for perfectionists...
    Again for perfectionists, a cap to ground from the anode of the first stage should remove the boost above 20KHz. All is providing the design of the phono stage has not changed from the schematic which can be found on the web.... if it's correct then 100pF should be the best value here.

    Interestingly, the RIAA stage works at such high impedances that layout issues of this hand built unit could be expected to make very minor differences to RIAA accuracy due to stray capacitances... it would also make the valve used in this position a particularly sensitive choice where "tube rolling" could have more effect than usual!
    davidsrsb likes this.
  5. Dowser

    Dowser Learning to bodge again..

    Ha-ha Jez, you can be such a twat sometimes :) This is just your opinion I guess, you have never actually tried a DL110 into an MC stage? Again, I'd suggest people try if they have the option (keep volume low at first if you like, but I have never experienced overload distortion [to my knowledge, ha-ha!]). It's a very simple test to do...nothing will go bang...you will either like it or you will not :)
  6. Arkless Electronics

    Arkless Electronics Trade: Amp design and repairs.

    Ha well people are it seems grossly offended by technical facts....
    I repeat my earlier advice. 2mV+ into a stage designed for 0.5mV may well cause distortion, especially in the treble, and largely depending on the overload margins of the particular phono stage (it will be lessened by the high output impedance forming a potential divider with the MC input loading though). Also it is optimised for 47K loading so what effect 100R or so has on the FR is anyone's business!
    Indeed nothing will go bang and as some like grossly inaccurate sound some will no doubt like it:D
  7. Fretbuzz

    Fretbuzz pfm Member

    I tried a DL-110 with many stage options... Sounded bloody awful through the MC input! Way overblown. As you say no harm in trying yourself though ...

    It also seemed under-fed from low gain MM. 46 dB seemed best in my set up.
  8. Dowser

    Dowser Learning to bodge again..

    So, now you are discussing more sensibly :)

    I *think* the OP impedance of the dl110 is around 100 ohms, and feeding it into an MC stage instead of MM will see the output of the dl110 drop considerably? There’s a bit of further information if you use google.

    I rarely state anything unless it is from personal experience - hence me suggesting people try it. I am not an engineer, I struggled to even be a half decent technician, but I do believe forums like this are about sharing our experiences...not just our beliefs ;)

    As for an inaccurate sound feeding a dl110 into an MC stage, this is again your belief, you have never actually tried it? All I know is that i preferred the sound into MC so far every time i have tried it with a dl110 (i have 3, i like them so much as a budget cart...well, they used to be budget!). Maybe not all MC stages will work well, but Naim 323s certainly do IMVHO.

    Still no comparison compared to an Asaka into a Curl head amp and then into a Croft MM stage of course, but I like the Denon.
  9. Arkless Electronics

    Arkless Electronics Trade: Amp design and repairs.

    Sounds about what I'd expect.
  10. Dowser

    Dowser Learning to bodge again..

    Which MC stages did you try? I’ve tried Naim and Moth MM vs MC and preferred both into MC. With MM only stages I prefer it with DIY SUs or a head amp.
  11. Arkless Electronics

    Arkless Electronics Trade: Amp design and repairs.

    If you mean SUT then that could have some interesting FR effects... with the DL110 having a 160 R output impedance and most SUT's being for 5 -15 R.... could be a wide range of peaking or HF roll off depending on the SUT I guess...

    Strangely the specs say the loading for the 110 should be "above 47K Ohms"... maybe slightly mistranslated from Japanese?
  12. Darth Vader

    Darth Vader From the Dark Side

    Yes and I think that nails it. If the high output MC expects to see a load of 47KΩ (MM input) but instead sees somewhere around 500Ω (MC input) then the generator will be trying to deliver around 100x its expected design current for any given voltage. This means that the generator will stiffen up i.e be harder to move as more energy will be required. The HF has tidily groove displacement even though the recording RIAA will boost the treble but the bass groove displacement will be much larger even though it is cut during recording. Thus on play back I would expect much diminished treble after the RIAA cut but with bass far less so after its RIAA boost. So the bass is not being unnaturally boosted rather the treble is being cut. Well it sounds good no?


  13. Fretbuzz

    Fretbuzz pfm Member

    Had an iFi iPhono at the time - tried both MC and MM variations on that. Also tried it with an Audio Note RIAA-Zero (MM). This is only 36 dB which wasn't enough, but adding a SUT it again sounded really overblown. (Note I wasn't expecting the 110 to work with the AN without or without SUT - still had the cart then so just experimented.)

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