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    Would a ST-70 be better for me than a ST-120?

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    kevinmi

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    Join date : 2009-11-17

    Would a ST-70 be better for me than a ST-120?

    Post by kevinmi on Fri Nov 24, 2017 1:58 pm

    Here's the background story: I built a ST-120 amp a few years back, and it performs flawlessly driving my modified Klipsch K-Horns. I'm about to relocate my listening room to a smaller space, and will be doing more of a close range type of listening. I was wondering if I could get a different sound from the EL-34 tube family in a ST-70 amp than my current ST-120 with KT-88 or KT- 120 tubes? I would like to get that warm tube sound. Don't get me wrong- the ST-120 is a great amp, but I don't need all that power with my new set up.
     Is it possible to use EL-34 tubes in my current amp to achieve the sound I want, or should I build a new amp? I would like to build an amp with upgraded caps and any other components to get the best sound I can.
     I am using a Cary SLP 98P preamp with the F1 upgrade, and listen mostly to analog sources, like vinyl and reel to reel tapes.
    Any and all opinions/comments/criticisizms are welcome and encouraged!
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    Peter W.

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    Location : Melrose Park, PA

    Re: Would a ST-70 be better for me than a ST-120?

    Post by Peter W. on Fri Nov 24, 2017 3:13 pm

    kevinmi wrote:Here's the background story: I built a ST-120 amp a few years back, and it performs flawlessly driving my modified Klipsch K-Horns. I'm about to relocate my listening room to a smaller space, and will be doing more of a close range type of listening. I was wondering if I could get a different sound from the EL-34 tube family in a ST-70 amp than my current ST-120 with KT-88 or KT- 120 tubes? I would like to get that warm tube sound. Don't get me wrong- the ST-120 is a great amp, but I don't need all that power with my new set up.
     Is it possible to use EL-34 tubes in my current amp to achieve the sound I want, or should I build a new amp? I would like to build an amp with upgraded caps and any other components to get the best sound I can.
     I am using a Cary SLP 98P preamp with the F1 upgrade, and listen mostly to analog sources, like vinyl and reel to reel tapes.
    Any and all opinions/comments/criticisizms are welcome and encouraged!

    A few things:
    a) Headroom is always, repeat, ALWAYS good.
    b) The difference between 35 wpc and 60 wpc is about 3dB.
    c) Given the quality of VTA products, I doubt that there is any difference in sound between the two amps that would not be explained by the tubes - as in any difference in nature between brand X and brand Y vs. EL-34 family vs. KT80/90/120.

    Now, if it so-happens that you want to build another amp, that is an entirely different horse of an entirely different color. But you will get as much of a warm-tube-sound out of the 120 as the 70, with the added headroom to handle those troublesome transients.

    Enjoy!
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    kevinmi

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    Re: Would a ST-70 be better for me than a ST-120?

    Post by kevinmi on Fri Nov 24, 2017 3:37 pm

    Part of me does want to build a new amp just for the fun of it, but I don't want to spend the time and money without hearing any difference. I really don't have to worry about headroom with speakers that are at least 104 db/w. I have a pair of EL-84 mono amps that put out 5.5 watts that will fill the room with sound at half volume!
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    Peter W.

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    Re: Would a ST-70 be better for me than a ST-120?

    Post by Peter W. on Fri Nov 24, 2017 3:49 pm

    kevinmi wrote:Part of me does want to build a new amp just for the fun of it, but I don't want to spend the time and money without hearing any difference. I really don't have to worry about headroom with speakers that are at least 104 db/w. I have a pair of EL-84 mono amps that put out 5.5 watts that will fill the room with sound at half volume!

    You will hear the difference with those troublesome transients. The 120 will sound better. Given that you are running Klipsch speakers, that may be less of a consideration, however.
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    j beede

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    Re: Would a ST-70 be better for me than a ST-120?

    Post by j beede on Fri Nov 24, 2017 4:51 pm

    Headroom is not always better (in every way). For example, it may be that in a smaller room your VTA-120 makes a good "winter" amp in that it noticeably raises the ambient temperature--in a pleasant way. Smallish room in the summertime? Not so pleasant.

    If you are anxious to build a new, smaller amp you might consider a solid state rectified, push pull, ultralinear EL-84 design. If I owned high sensitivity speakers this is the path I would take. I suspect that such an amp would dissipate 100W or less at idle. The more I listen to EL-84 amps the more I appreciate this overachieving "little" tube that produces big sound.
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    kevinmi

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    Re: Would a ST-70 be better for me than a ST-120?

    Post by kevinmi on Fri Nov 24, 2017 5:15 pm

    Being in Michigan, I do appreciate the warmth of all those tubes glowing in the wintertime!
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    kevinmi

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    Re: Would a ST-70 be better for me than a ST-120?

    Post by kevinmi on Fri Nov 24, 2017 5:19 pm

    j beede wrote:Headroom is not always better (in every way). For example, it may be that in a smaller room your VTA-120 makes a good "winter" amp in that it noticeably raises the ambient temperature--in a pleasant way. Smallish room in the summertime? Not so pleasant.

    If you are anxious to build a new, smaller amp you might consider a solid state rectified, push pull, ultralinear EL-84 design. If I owned high sensitivity speakers this is the path I would take. I suspect that such an amp would dissipate 100W or less at idle. The more I listen to EL-84 amps the more I appreciate this overachieving "little" tube that produces big sound.

    My EL-84 amps are single ended with SS rectification, and they sound wonderful, although I am a bigger fan of tube rectification.
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    sKiZo

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    Location : Michigan USA

    Re: Would a ST-70 be better for me than a ST-120?

    Post by sKiZo on Fri Nov 24, 2017 7:00 pm

    Might want to try some 6550 power tubes? Don't quote me on this, but seems to me that would drop your max to 50wpc vice the 60+ of the KT88 ... they should work fine with no mods.
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    arledgsc

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    Location : SF Bay CA

    Re: Would a ST-70 be better for me than a ST-120?

    Post by arledgsc on Sat Nov 25, 2017 10:31 am

    If it was me I would keep the ST120 as it will have more power headroom while operating solely in Class A using KT88s versus the EL34s.

    But the ST70 kits are cheap enough to find out for yourself.

    wildiowa

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    Join date : 2012-03-19

    Re: Would a ST-70 be better for me than a ST-120?

    Post by wildiowa on Sat Nov 25, 2017 11:56 am

    The ST70 in a smaller room with efficient speakers will be excellent. Even with less efficient speakers, excellent. With a large and small venue I would prefer the variety of two distinct amps comparing performance, characteristics, sound, dependability etc. Vive la difference!
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    Peter W.

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    Re: Would a ST-70 be better for me than a ST-120?

    Post by Peter W. on Sat Nov 25, 2017 12:14 pm

    Does anyone think that VTA will come out with an ST35 clone? Might be the ticket in these situations.
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    Bob Latino
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    Re: Would a ST-70 be better for me than a ST-120?

    Post by Bob Latino on Sat Nov 25, 2017 2:17 pm

    Peter W. wrote:Does anyone think that VTA will come out with an ST35 clone?  Might be the ticket in these situations.

    Read the Sticky above on rebuilding the original Dynaco ST-35. Dynakitparts already sells a very good ST-35 kit so another one from VTA doesn't make sense .. You don't really need any "upgrades" to have an ST-35 give you quality sound. The only limitations on the ST-35 amp are power limitations. Any ST-70 type amp will play about 3 dB louder than the ST-35. Paired with higher efficiency speakers and a good preamp, the Dynaco ST-35 will give you quality sound.

    Bob
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    corndog71

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    Re: Would a ST-70 be better for me than a ST-120?

    Post by corndog71 on Sat Nov 25, 2017 3:51 pm

    I’ve built several modded versions of the ST35. It’s a great little amp. I highly recommend the EFB mod as it improves several aspects of the design and performance.

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