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    Preamp on budget for VTAST70



    Posts : 21
    Join date : 2017-05-20

    Preamp on budget for VTAST70

    Post by rymi on Mon Aug 28, 2017 8:59 am

    Im using a VTA ST70 with an attenuator in a box and a pair of Klipsch Cornwalls. Im able to control my DAC and Phono Stage perfectly well with this setup.

    However, I am missing tone control on some rougher sounding recordings. I have also never heard an active preamp with my speakers and amp so there is that "what am I missing" factor.

    So im considering a preamp with tone control but only have about 500 bucks. The only things I have considered is the VTA SP9 but the kit is a little above my ability and more than I wanted to spend. I also thought about a PAS3 or PAS3X but they are not showing up locally and I cant justify paying a premium for them online just to have to start updating the thing to be able to play it everyday.

    So I would like to hear your opinions.

    Tone control aside, do you think I will achieve any sonic benefit beyond my current setup (which doesn't "need" more gain.)? What ramifications do I need to consider?

    Peter W.

    Posts : 709
    Join date : 2016-08-07
    Location : Melrose Park, PA

    Re: Preamp on budget for VTAST70

    Post by Peter W. on Mon Aug 28, 2017 10:34 am

    rymi wrote:

    So I would like to hear your opinions.

    Tone control aside, do you think I will achieve any sonic benefit beyond my current setup (which doesn't "need" more gain.)? What ramifications do I need to consider?

    OK. Opinions - I write for myself, and as it happens, I have no less than five pre-amps in use at this moment. Also as it happens, I paid less than $500 for all of them - although that may not be indicative of the present market. Of the five, one I built from a kit, not relevant to this discussion as they are readily available built. And two required minor
    (and simple) repairs which I am sure accounted for the price(s) I paid.

    They are in rank order of my enjoyment of them:

    Revox A720 tuner/pre-amp: Paid $250 for it in 2008. Took $12 worth of caps & lamps to make 100%. I purchased two previously to 2008 for $190 combined, neither working. I traded the two + $150 cash to a gentleman in Tennessee for one working unit. That unit is now with my Grand Daughter. The incumbent will be pried from my cold, dead fingers.   NOTE: This could be considered an "exotic" and repairs are not intuitive as with most of the other items listed below. Unless you are prepared for this, DO NOT take on this option unless you hear the unit in operation first.

    Harman Kardon Citation 17: Paid $125 in 2012. Needed lamps (a real PITA) and two caps. One helluva pre-amp.    It comes in two versions, you want the one with the slide controls.

    Dynaco PAS3X (you want the one with the X-tone controls. I updated the power-supply and went with Mil.Spec. 5751 tubes ILO 12AX7s. That and cleaned control was about all that it needed other than a few ordinary caps - which anything of that vintage should have. Paid $100 in 2007.

    Dynaco PAT5 BiFet:  Built this from a kit in 1978, paid $35 for the kit from the Dynaco Blackwood Factory closeout. It lives at our summer house and is used every day we are there. Many bells and whistles, as well as an EPL loop. Ordinarily less than $200 in the after-market. BE SURE it is the BiFet version!  

    Dynaco PAT4: One of the great sleeper pre-amps out there, in my opinion. Does many things blamelessly, has X-type tone controls, as well as a head-amp and front-panel microphone inputs and will drive headphones. Meaning that one may have two (2) phono inputs with very minor modifications. I paid $19 for my incumbent, which needed serious cleaning, a few caps, and much rust-removal from the cover. This was at Kutztown last year. I paid $30 for another example, also last year, that needed three small-value caps, cleaning, internal cleaning and some power-supply work, about 6 therapeutic hours in all, and was traded for some very nice tubes.

    Sorry for the premature post - the above is the hardware end. Now the Software - Wetware end of things:

    Do you "NEED" more gain - that would depend. If your present set-up will deliver 2 clean volts to the power-amp, you have all that you 'need'. But, if you want to have more flexibility, having the capacity to deliver up to 15 V can be useful. What you are getting for that additional gain would also be the tone-controls - to various levels of sophistication - and other signal processing options (short of an equalizer) that can be very useful, as you suggest, for some of the 'rougher recordings'. Personally, I have run several amps directly from components with a 2V output limit, and always have the 'perception' that I do not have the control I want. Not quite a reality, but there is the fact that having a 0 - 13 V spread on an audio taper can be more precise than a 2V spread on a linear or audio taper. All my active systems use either a preamp (or integrated amp), none use direct feed except when testing on the bench. And the flexibility of tone controls and filters can be very useful.

    Ultimately, it is your choice.

    Posts : 1435
    Join date : 2008-11-30

    Re: Preamp on budget for VTAST70

    Post by tubes4hifi on Tue Aug 29, 2017 8:38 am

    with just a little above average ability, you can build an SP9 preamp with tone controls for under $450. The PCB kit is $200.
    Add the power transformer and tubes for around $100. Then you just need a chassis, you can usually find a working PAT4 or PAT5 on ebay for under $100.
    Gut out all the parts, install the SP9 board and power transformer, hook up the volume, and run the output of the selector switch to the input of the board and you're all done.

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    Re: Preamp on budget for VTAST70

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