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    Help with new system

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    thermionicvinyl

    Posts : 11
    Join date : 2018-06-10

    Help with new system

    Post by thermionicvinyl on Sun Jun 10, 2018 6:15 pm

    I recently complete my 'dream system' with these specs:

    -VPI Scout Prime Turntable
    -Soundsmtih Aida Cartridge
    -PH-16X
    -VTA ST-120 w/KT120
    -KEF LS50's

    It sounds absolutely stunning but...even when the stepped attenuator on the ST-120 is cranked to the max, it is still only moderately loud. For most music this is fine as I tend to listen at a moderate volume but when I listen to classical/acoustic music, I love being able to turn it up to concert levels.

    Right now I have my PH-16X's RCA outputs directly connected to the RCA inputs of my ST-120, is this ok to do or is it pessary to have another preamp in between them? I'm certain a preamp will increase the maximum volume quite a bit but at what cost of sound quality? I do have to admit the simplicity of phonostage straight to power amp is nice but it could always be louder at the moment.
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    Bob Latino
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    Posts : 2689
    Join date : 2008-11-26
    Location : Massachusetts

    Re: Help with new system

    Post by Bob Latino on Sun Jun 10, 2018 8:14 pm

    thermionicvinyl wrote:I recently complete my 'dream system' with these specs:

    -VPI Scout Prime Turntable
    -Soundsmtih Aida Cartridge
    -PH-16X
    -VTA ST-120 w/KT120
    -KEF LS50's

    It sounds absolutely stunning but...even when the stepped attenuator on the ST-120 is cranked to the max, it is still only moderately loud. For most music this is fine as I tend to listen at a moderate volume but when I listen to classical/acoustic music, I love being able to turn it up to concert levels.

    Right now I have my PH-16X's RCA outputs directly connected to the RCA inputs of my ST-120, is this ok to do or is it pessary to have another preamp in between them? I'm certain a preamp will increase the maximum volume quite a bit but at what cost of sound quality? I do have to admit the simplicity of phonostage straight to power amp is nice but it could always be louder at the moment.

    The KEF LS50's are 85 dB efficient which means that they have very LOW efficiency and eat up a lot of amplifier power without much volume. What you need for more volume is either a new set of speakers that have a much higher efficiency OR an amplifier with much more power.

    Bob
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    pichacker

    Posts : 61
    Join date : 2016-08-01
    Age : 54
    Location : Near to London - UK

    Re: Help with new system

    Post by pichacker on Mon Jun 11, 2018 7:18 am

    Bob, if the amp is not distorting then maybe a pre-amp is the solution. If It is clipping then your comments are of course spot on.
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    Peter W.

    Posts : 924
    Join date : 2016-08-07
    Location : Melrose Park, PA

    Re: Help with new system

    Post by Peter W. on Mon Jun 11, 2018 8:50 am

    What Bob said. And:

    A 5.5" woofer coupled with a 1" tweeter, and a 79Hz - 28kHz (±3dB) frequency range is simply not going to be a very 'loud' speaker. 60 watts RMS is more than enough to drive it at its limits, but those are quite narrow. In terms of the issue you describe the speakers are the limiting factor. Not the amp.

    More power *will not* give you more volume given that the maximum output listed for the system is 106 dB. And adding a pre-amp allowing for over-voltage into the VTA120 will only drive it to clipping, not good for the amp or the speakers.

    There are a range of solutions that start with adding a properly matching sub-woofer to fill in the bottom end, to replacing the speakers altogether with devices with a broader frequency response and perhaps better efficiency. I drive a pair of AR3a speakers with 60 WPC/RMS in a moderately sized room, and they do just fine at 86dB efficiency.

    Pre-amps are useful, as they allow for multiple sources and some modification to the signal (tone controls), but they are a two-edged sword to the 'purist' adding another link to the chain between the source and the speakers. However, I find them more contributory than deductive overall.
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    skriefal

    Posts : 132
    Join date : 2011-09-20
    Location : Utah, USA

    Re: Help with new system

    Post by skriefal on Mon Jun 11, 2018 8:23 pm

    Is this the moving magnet (45dB) or the moving coil (55dB) version of the PH16? If the former then there is almost certainly not enough gain to drive the ST70 to maximum output. You'll likely need to add a line stage pre-amp between the PH16 and the ST70.
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    Tube Nube

    Posts : 682
    Join date : 2008-12-06
    Age : 55
    Location : Calgary, AB

    Re: Help with new system

    Post by Tube Nube on Tue Jun 12, 2018 8:27 am

    A number of excellent suggestions above.

    One piece of imformation we’re lacking is the size of the listening room.

    Something you can do to help pin down the culprit is swap in any old cd player, tape deck, or tuner for your phono. That way you’ll know straight away if your phono is delivering a line level signal to the amp.

    EDIT

    Sorry to do this to you, but here’s yet another issue. Your cartridge is a so called high out put moving coil, so designed that they are meant to work with phonos expecting moving magnet cartridge output levels. Trouble is often, as is the case with your cartridge, that high output (2.2 mV) is not as high as typical moving magnet carts (3.5 mV).

    My guess is the cd player will play much louder than your turntable & phono.

    Solutions? If you really don’t want to add a pre-amp, you could buy or build a step-up transformer. One such device is offered by K&K audio which I use myself with my low output MC cartridge. They can be built / bought with different gain settings. "Tuning" the SUT to your cartridge only requires choosing the right interchangeable resistor value for installation. The instructions spell it all out very clearly, considering what a complex subject it might seem to be from reading about SUT's on the web.

    Another option is a "head amp" a.k.a. "pre-pre-amp" to boost the cartridge signal to a level the phono stage is happy to see.

    There are arguments for and against each approach. I was persuaded that putting a transformer in line was adding less distortion or noise than adding another amplification stage. I've not been able to find any information on how an SUT might distort things.
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    tubes4hifi
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    Re: Help with new system

    Post by tubes4hifi on Tue Jun 12, 2018 12:39 pm

    as with TubeNube, I wouldn't call 2.5mv output a high output MC, that's medium output. To get the same amount of volume you would have with a CD player, you're going to need an SUT with 14 to 20db of gain,
    in addition to running thru a standard phono preamp (40-45db of gain) like the PH16. SUTS are totally passive transformers and do not add any distortion.
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    solderblob

    Posts : 43
    Join date : 2018-05-20
    Location : Placerville, California

    Re: Help with new system

    Post by solderblob on Tue Jun 12, 2018 12:58 pm

    Ran across one of Paul McGowan's videos which touches on this subject:

    https://www.youtube.com/watch?v=i1fpY7WeigM

    Dave

    thermionicvinyl

    Posts : 11
    Join date : 2018-06-10

    Re: Help with new system

    Post by thermionicvinyl on Sat Jun 16, 2018 2:51 pm

    Will a preamp (for example a SP14 from you guys) degrade the sound quality or enhance it, despite the extra signal processing? Soundsmith recommends you do not use a transformer with his cartridges so that's why I ask.
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    tubes4hifi
    Admin

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    Re: Help with new system

    Post by tubes4hifi on Sat Jun 16, 2018 3:19 pm

    that's a very subjective question, but I'll bet 90% of readers think a preamp does enhance the sound, that's why we like tubes, but of course it's more amplification and processing.
    I prefer a tube preamp to a passive preamp even when I don't need the gain, it sounds better to my ears, and in alot of systems is more linear because of impedance matching.

    thermionicvinyl

    Posts : 11
    Join date : 2018-06-10

    Re: Help with new system

    Post by thermionicvinyl on Sun Jun 17, 2018 12:47 pm

    tubes4hifi wrote:that's a very subjective question, but I'll bet 90% of readers think a preamp does enhance the sound, that's why we like tubes, but of course it's more amplification and processing.
    I prefer a tube preamp to a passive preamp even when I don't need the gain, it sounds better to my ears, and in alot of systems is more linear because of impedance matching.

    What exactly is impedance matching?
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    tubes4hifi
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    Re: Help with new system

    Post by tubes4hifi on Sun Jun 17, 2018 3:20 pm

    google, this comes up first . . .
    https://en.wikipedia.org/wiki/Impedance_matching

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