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    Decisions, Decisions, Decisions!

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    Allang

    Posts : 2
    Join date : 2012-01-23

    Decisions, Decisions, Decisions!

    Post by Allang on Tue Jan 24, 2012 3:46 pm

    Hi All,

    I'm going to purchase either an ST70 or ST120 kit in the near future. I have Monitor Audio Silver RS6 speakers and they are rated for 40-120 watts. The sensitivity is 91db @ 1 watt. Will I have problems with the ST70 trying to drive these speakers? I would prefer to get the ST70 because of cost restraints. As a last resort I will go for the ST120. Any advice is welcome.

    Allan Smile

    captn

    Posts : 14
    Join date : 2010-01-17
    Location : Coastal Virginia

    Re: Decisions, Decisions, Decisions!

    Post by captn on Tue Jan 24, 2012 4:37 pm

    I have a Latino ST70 driving Wharfedale EVO2 speakers. My speakers are rated at 88db sensitivity and the ST70 is more than adequate for driving these to very loud levels with excellent clarity and imaging. Most of my listening is done at moderate volume levels so more amplifier power is not really needed. Also my listening room is quite small which is a further reason big power is not needed in my case.

    Don't get me wrong though, the ST120 is an excellent choice and the extra power might suit your needs, particularly if you like high sound levels or your room is large. I think you will be pleased with either amplifier as they both have similar sound characteristics. Maybe another forum member can give you some other insights which may help with your decision.

    mantha3

    Posts : 298
    Join date : 2010-11-10

    Re: Decisions, Decisions, Decisions!

    Post by mantha3 on Tue Jan 24, 2012 4:47 pm

    I have the ST120 and I have these running 91dB speaker I built. Fantastic. I'm sure the ST70 would be as well.

    My advice... Get the ST120 and get the capacitor upgrade. Buy the kit and build yourself. Save some $$ and have a fun and rewarding experience doing the build. The instructions are so good it is just busy work doign the build. Take resistor out of bag 3 and put in spot #22 and solder... Next step.. etc. Just read the step, do it and re-read and dbl check.. Then put a black check mark on the step in the instructions. Buy a $18 Wellman soldering iron from Lowes and some good solder.

    Oh, get the Attenuator option as well.

    Buy the cheaper tubes from an online spot. Later you can upgrade. Shuguang tubes are cheap and do really work well. PS - I run an Attenuator and 91 dB speakers and the Hi Gain VTA board is great

    Bob Latino
    Admin

    Posts : 2378
    Join date : 2008-11-26
    Location : Massachusetts

    Re: Decisions, Decisions, Decisions!

    Post by Bob Latino on Tue Jan 24, 2012 6:00 pm

    Hi Allan,

    The difference between the VTA ST-70 and the VTA ST-120 is strictly a matter of POWER. Clarity, soundstaging etc. are all pretty much the same from amp to amp. Subtle differences may be heard between the two amps sometimes because the ST-70 uses EL34 output tubes and the ST-120 uses KT88 output tubes.

    Re: Power .. The VTA ST-70 and ST-120 amps are both rated conservatively as to power output. The ST-70 in an independent test (not done by me) reached 45 WPC in ultralinear and 21 WPC in triode mode without clipping. > ST-70 test link

    The VTA ST-120 is really a 72 - 75 WPC amp in ultralinear and about 35 WPC in triode if tested the same way.

    The three key things to consider when trying to decide how much power you need are ..

    1. The efficiency of your speakers
    2. The size of your room
    3. How loud you play the music

    IMHO > With 91 dB speakers in an average sized room, the ST-70 would probably have enough power for your needs.

    Bob

    Tube Nube

    Posts : 603
    Join date : 2008-12-06
    Age : 53
    Location : Calgary, AB

    Re: Decisions, Decisions, Decisions!

    Post by Tube Nube on Wed Jan 25, 2012 12:47 pm

    Just to add a comment, 91 db is a pretty sensitive speaker, and iirc, will be twice as loud as 88db.

    I initially played my st 70 into a pair of Linns that were 87 or 88db, no problem in a room 12 by 24'.

    Then i built a pair that are in you neighborhood of 91 or 92. The amp has enough power to play too loud by far.

    One other thing about more power -- maybe someone can confirm -- when played at the same volume, does the more powerful amp have a better ability to follow dynamic changes in the music relative to the smaller amp?

    Bob Latino
    Admin

    Posts : 2378
    Join date : 2008-11-26
    Location : Massachusetts

    Re: Decisions, Decisions, Decisions!

    Post by Bob Latino on Wed Jan 25, 2012 12:51 pm

    Tube Nube,

    Yes - A larger amp has more "headroom" and will respond better on musical peaks than a smaller amp.

    Bob

    Tube Nube

    Posts : 603
    Join date : 2008-12-06
    Age : 53
    Location : Calgary, AB

    Re: Decisions, Decisions, Decisions!

    Post by Tube Nube on Wed Jan 25, 2012 3:30 pm

    Hi Bob,

    Thanks for confirming that! This, alone, might justify purchasing the "bigger" amp, even if the smaller 70 is easily capable of playing at sufficient volume.

    Allang, looks like you're looking at a choice between two options, and both of them are great. You can hardly go wrong! I hope you'll post-up on your choice and your progress with the build.

    kaner

    Posts : 88
    Join date : 2011-09-20

    Re: Decisions, Decisions, Decisions!

    Post by kaner on Wed Jan 25, 2012 11:46 pm

    I have the Monitor Audio Silver RX6's driven by the VTA ST70 and am really impressed. Plenty of power to fill a 16X20 room. In fact the sound fills the house more than anyone but me cares to hear. Those speakers are easy to drive and pair up nicely with the VTA ST70. I have no experience with the ST120 so I can't give you a comparison. But I can tell you I am happy with my setup.

    Jhoman

    Posts : 25
    Join date : 2010-01-03
    Age : 55
    Location : Meridian, MS

    ST120

    Post by Jhoman on Fri Jan 27, 2012 5:43 pm

    I have the ST120 with KT120s, playing through Klipsch Cornwalls,in a 20 x 20 room, I can fill the house with clear, detailed sound! I can tell you that just going from KT88s to the KT120 tubes made a huge difference in headroom and detail. Just my $.02..

    jeff

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