The good/bad of too much gain on MM or MC carts?

Discussion in 'Audio Hardware' started by raferx, Apr 17, 2014.

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  1. chervokas

    chervokas Senior Member

    Who knows? Could be a change in the feedback of the phono stage gain circuit as someone suggested (which might account for more wumpus bass, for example, though in my experience that doesn't necessarily equate to more accurate bass), if that's what's going on with the Sutherland. Could in fact be a loudness thing -- are you sure you're listening at exactly the same levels as you were before? You could use an SPL meter to try to make sure you're making the comparison at the same loudness at the listening position. Could be there's some kind of euphonic distortion as someone suggested. Could be you just like the voicing of the Sutherland more than the voicing of the line stage and now it's more prevalent. I wouldn't necessarily draw from your experience the conclusion that +5 dB of phono stage gain, just the gain alone, is the difference maker and that therefore more gain is inherently better.
     
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  2. [​IMG]
    This is a basic block diagram of the front end in your preamp. The resistor you are changing to adjust gain is the one called "R1". Your cart is feeding the point called "input"
     
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  3. raferx

    raferx Forum Resident Thread Starter

    Location:
    Vancouver, Canada
    Thanks for that thoughtful reply, great points! Especially the voicing aspect in comparison to my amp...
     
  4. blakep

    blakep Senior Member

    When I used the word "loud" to describe what's happening with increased gain, it may not be the best word (semantics).

    Assuming that one changes gain levels at the phono stage and then adjusts the line stage to play at exactly the same SPL's, my experience is (as Raferx's) that the overall change in presentation with increased (or decreased) gain at the phono stage can be dramatic.

    As such, I'm much more a believer in getting the gain right at the phono stage itself, and much more a skeptic of being able to dial up (or down) the gain at the line stage to "compensate" for a mismatch at the phono stage. There are others (much more knowledgeable and technically proficient than I) who have suggested that the first stage of amplification (ie. the phono stage) is really the critical one in getting analog right and that gain mismatches are pretty nasty.

    When you think about it, it makes perfect sense. If you can change the presentation that much simply by increasing or decreasing gain at the phono stage, the line stage is really just along for the ride after that. It's simply amplifying what it is fed by the cartridge/phono stage interface. It is, in essence, just another example, or continuation of the garbage-in/garbage-out theory with respect to the source, notwithstanding subjective preferences.
     
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  5. TarnishedEars

    TarnishedEars Forum Resident

    Location:
    The Seattle area
    Ok but I doubt that you'll understand my response any more.

    Here's your 30 second Electrical Engineering lesson:

    The equation for Op-Amp Gain is: Vout = Vin ( 1 + Rf/Rg ) where Rf is the size of the feedback resistor, Rg is the size of the ground resistor, and Vout is the output voltage, and Vin is the Input Voltage.

    Increasing the size of the feedback resistor, decreases the amount of negative feedback, and therefore increases the voltage gain of the op-amp.

    Many people in audio prefer low, or no negative-feedback designs. So I'm speculating that there is a slight possibility that you may prefer the sound when less feedback is employed.
     
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  6. Lowering the value of Rg increases the gain too. That is what is happening in this preamp.
     
  7. raferx

    raferx Forum Resident Thread Starter

    Location:
    Vancouver, Canada
    You're right, I don't completely understand, but I think I get your gist. Thank-you for the time to do that for me.
     
  8. TarnishedEars

    TarnishedEars Forum Resident

    Location:
    The Seattle area
    It looks like you are correct. The resistors do appear to be getting smaller for the larger gain settings. So it would appear that my guess about the feedback was wrong.
     
    Last edited: Apr 17, 2014
  9. Look at the PCB picture posted. Small value resistors are near the gain setting header. Also switchable feedback resistors are trouble because if they go open :yikes:
     
    Last edited: Apr 17, 2014
  10. psulioninks

    psulioninks Forum Resident

    Location:
    KC Chiefs Kingdom
    I, too, own a Sutherland Ph3D phone stage. I rip quite a bit of vinyl and have listened to rips by others as well.

    In general, I would say that my rips do not sound like other people's rips. The biggest difference I hear is with cymbals. I've never been one to get caught up in the whole "trying to make it sound like "live" music" routine. But I will say, with my cartridge and the Sutherland, cymbals sound real - like you are there in the event. They have a realness to them - a shimmer and decay. I find this is largely missing in other rips I have listened to. These others sound rolled-off and too polite (not real) - as if information is somewhat missing if that makes sense.

    Others that have listened to my rips have commented that they sound a tad bit "forward" and less "laid back" than others. I can't say for sure if their opinions hold merit...but I will say I have been pleased in what I have been able to accomplish with this phono stage.
     
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  11. raferx

    raferx Forum Resident Thread Starter

    Location:
    Vancouver, Canada
    This is a trip. I completely agree with you. A couple things first.
    I did a about two hours of critical listening earlier this evening, and doing A/B comparisons of several songs on different LPs I came to the realization that one of the things Chervokas said in an earlier post seems true for me: "Could be you just like the voicing of the Sutherland more than the voicing of the line stage and now it's more prevalent."
    To me the Sutherland sound has both changed and improved my system in many ways, far too many to list here (I'll save it for my review later), but a major conclusion I came to is that the sound is more real, more present. Certain instrument's tonal cues I was used to (from listening) through my integrated amp's phono stage had changed, especially cymbals. They no longer sounded "hi fi" if that makes sense, they just sounded absolutely real. As you say "a shimmer and decay." It was a really cool moment when I placed exactly how the sound had changed.
    The change was there from the start of running the Ph3D, but that little extra boost in gain, overrode my integrated's sound just enough to tip the sonic scales in favour of the Sutherland. It's a strange dance pairing electronics.
    So, in conclusion; more Sutherland coming through is better IMHO.
    I love this hobby, pursuit, passion... whatever you want to call being audiophile.
     
  12. Antares

    Antares Forum Resident

    Location:
    Flanders
    Indeed it is. And with some of this more specialized stuff, you can't always expect the same level of compatibility as with the more common / mass produced gear.

    To put things in perspective: 0.3 mV with 60 dB is exactly half of 6.0 mV with 40 dB (see online dB/gain calc.).

    About the cymbals, I don't have the numbers for your gear, but what you're hearing is most likely the result of the difference in capacitance loading between both phono inputs.
     
  13. raferx

    raferx Forum Resident Thread Starter

    Location:
    Vancouver, Canada
    I'm starting to feel my amp is a weak link :(

    To put things in perspective: 0.3 mV with 60 dB is exactly half of 6.0 mV with 40 dB (see online dB/gain calc.).[/quote]

    Does this mean I'll have to turn the volume knob twice as far for the same spl output?

    About the cymbals, I don't have the numbers for your gear, but what you're hearing is most likely the result of the difference in capacitance loading between both phono inputs.[/quote]

    Could you please explain this further (slow, I am dumb).

    Many thanks Antares.
     
  14. Antares

    Antares Forum Resident

    Location:
    Flanders
    Maybe not the amp in itself, but the electrical match with the phono stage could be better (although you're compensating for it with the gain jumpers).

    Not twice as far, but 6 dB higher (to make up for the difference between 600 mV and 300 mV outputs from the phono stage in this example). I'm guessing maybe 1 to 2 "hours" on the volume "clock".

    Treble response of MM carts like the Exakt is highly dependent on the electrical capacitance and resistance they are presented with by the phono stage. Resistance is more or less standardized at 47 kOhm for MM, but capacitance can vary quite substantially between phono stages. This will shift the treble peak left (more capacitance) or right (less capacitance) in the audible high frequency spectrum and will impact the character of the sound accordingly. I'm guessing maybe the Sutherland has less capacitance than your amp's phono stage, resulting in better treble extension (and overtones/shimmer on the cymbals). MC carts are less sensitive to capacitance, since their electrical reonance peak is much higher up in the spectrum (above human hearing), but they will still respond somewhat to resistive loading (hence the different Ohms settings on the Sutherland).

    Happy listening!
     
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  15. raferx

    raferx Forum Resident Thread Starter

    Location:
    Vancouver, Canada
    Many thanks for that layman's explanation Antares, much appreciated.

    Cheers, and happy Easter weekend to you and your family.

    –R
     
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  16. chervokas

    chervokas Senior Member

    Yeah, but he's using the same phono stage, just at different gain settings, so presumably the capacitance loading on the cartridge isn't changing when he's going from 40 dB on the Sutherland to 45 dB on the Sutherland. Any differences the OP is hearing between those two gain settings on the Sutherland aren't likely to be due to the capacitance loading of the cart.
     
    Last edited: Apr 20, 2014
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  17. missan

    missan Forum Resident

    Location:
    Stockholm
    Usually what we hear is just a difference in loudness, IME. And it´s the initial impression that counts, so if this is louder it will sound better.
     
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  18. chervokas

    chervokas Senior Member

    Could be in this case for sure. He could get an SPL meter and make sure the loudness at the listening position is the same with either gain setting, marking the proper line stage volume knob settings to get the same loudness at the listening position so that he can easily and accurately flip back and forth between the two phono gain settings at the same listening loudness without exposing his ears to the louder sound of the higher gain setting as he's searching for the proper line stage level, if he really wants to listen for that.
     
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  19. ellingtonic

    ellingtonic Forum Resident

    That's a great idea. I know there are several free and cheap iPhone SPL apps too. Presumably they exist for other platforms as well.
     
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  20. Antares

    Antares Forum Resident

    Location:
    Flanders
    Yes, you are correct. I was obviously referring to the change between the Sutherland and onboard phono stage.

    About the gain, in my experience, when a 6-7 mV cart with 40 dB gain is lacking in punch, this is being lost in the connection between the phono pre and the amp and can't be recovered downstream - it will sound flat no matter how loud you turn it up. You have to go back and turn it up at the source (which is what raferx has done intuitively). YMMV of course.
     
  21. jupiterboy

    jupiterboy Forum Residue

    Location:
    Buffalo, NY
    I have a 4mV cart, which is OK @40db but @44db the sound is punchy but I lose lots of micro detail in the mids in exchange for that punchy sound.
     
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  22. raferx

    raferx Forum Resident Thread Starter

    Location:
    Vancouver, Canada
    Great idea to have one of these iPhone SPL apps for doing this kind of stuff. Thanks!
     
  23. raferx

    raferx Forum Resident Thread Starter

    Location:
    Vancouver, Canada
    After much going back and forth, and several hours critical listening (remember, this phono stage is brand new, and brand new in my system with brand new interconnects), I've decided to stick with the 47K/40dB gain setting on the Sutherland. Yes the sound was punchier at 47K/45dB, but was fatiguing after a few hours – which is the last thing I 'm building this system to have – and that the punchiness I was hearing/feeling was ultimately sacrificing micro-detail, overall tonal balance, true shimmer and decay on cymbals and percussion, it was roughing up transients on bowed instruments and the leading/trailing edges of piano and windwoods and gave some brass a reedy quality. basically, a degree of distortion.
    I also agree with an earlier comment that perhaps in the end, as much as I enjoy the Exact-2 (it's the best cart I've had so far) it ultimately has a flatter frequency response, and that initial punchiness/dynamics that the Ph3D was boosting through at the 45dB setting is what I want in a cart. So the 20x2L I want to replace the Exact-2 with should solve that (I hope), albeit with detail, transparency and timbral accuracy not being sacrificed.
    This was a cool, and fun experiment for me and ultimately a real lesson and training session for critical listening. Thanks to everyone who responded and all the great suggestions.
    I hope I can be as helpful someday for all of you.
    Cheers,
    –R
     
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  24. Antares

    Antares Forum Resident

    Location:
    Flanders
    I know, and I was surprised already when you didn't chime in with a word of caution to raferx (like blakep did) about using too much gain.
     
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  25. ellingtonic

    ellingtonic Forum Resident

    I'm not surprised you preferred the lower gain setting with that cartridge. You may want to check again in a couple of months. It's possible that it may change once it's fully broken in, but it'll probably just confirm that you have it set to the best option for your set up.

    It's so nice to have a flexible phono stage!
     
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