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Bob Latino LTA ST120 OR QS MID MONO'S


JRS94

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I have a ST-120 I built about 9 years ago that I had hooked up to my K-Horns for several years. I actually noticed more bass than with the SS amp it replaced (McIntosh). You certainly don't need all the power of the ST-120 to run K-Horns! The ST-120 amp is super quiet, so it is a good match for sensitive horn speakers.

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Kevinmi

Thanks ,

I know either the QS Mid Monos or the ST 120 will have plenty of power, I'm going that route just in case I decide to change speakers later. I'm at the point where I just need to pick 1 and order. Did you do any of the upgrades with your ST 120? Capacitors, volume attenuator, auto bias? I am considerring those and asking if we can leave the old preamp power connections out. Maybe put a bias readout or something in those holes. Watt meter would be cool. What tubes did you end up with? I won't be building my own. Just no time. Plug and play for me right now. 

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On 1/13/2020 at 10:24 AM, JRS94 said:

Kevinmi

Thanks ,

I know either the QS Mid Monos or the ST 120 will have plenty of power, I'm going that route just in case I decide to change speakers later. I'm at the point where I just need to pick 1 and order. Did you do any of the upgrades with your ST 120? Capacitors, volume attenuator, auto bias? I am considerring those and asking if we can leave the old preamp power connections out. Maybe put a bias readout or something in those holes. Watt meter would be cool. What tubes did you end up with? I won't be building my own. Just no time. Plug and play for me right now. 

I have every mod available- the Russian PIO caps, volume control, auto bias board. I am using very expensive vintage Tung-Sol 6550 power tubes. I have had good luck with new production Gold Lion KT-88 tubes and Tung-Sol KT-120 tubes as well. I use different vintage tubes in the front, with Amperex being my favorite. Rectifier tube is a Mullard GZ-33.

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Thanks , Bob kind of talked me out of the auto bias, I'm going to do the caps  and volume for sure. I guess I can add auto bias later if i get tired of biasing. $150 to add it now. Still thinking on that part.  I'm going to start out with tung sol KT 120's then probably start collecting tubes! thanks for your help

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Bob is right about the AB. I got it and had issues getting it installed. Everything was great prior to adding this. I got the PIO caps and the attenuator these are positives. I’m using KT120s, a center Brimar CV4003 and Bob's NOS RCA 5963’s on the outside. Amp sounds great and bias was always very close when I checked it monthly. It’s now spot on w/ the AB but that complicated it. The AB does have a delay so I got a Weber WS-1t  s/s rectifier. All in all, it’s a great sounding amp. 

Edited by amped
clarity and tube type corrections
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12 hours ago, kevinmi said:

The auto bias board is a pain to install as a retro fit. It is best to install it during the initial build.I think the benefits far outweigh the cost of the board.

I agree about the install- do it all at once.

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3 hours ago, xoundmind said:


can you explain the workings of the auto bias function? How hands on? 

 

Here's the manual that came with the board. http://www.***.cz/files/AB-Q_ST-70_ST120_manual.pdf

Once it's set to the desired bias voltage by the installer, there's no real hands on. Make sure they know what tubes you're using and clear it (voltage) with Bob.

I was still checking my bias for a bit after installing but all 4 tubes were always the same (as designed). Hope this helps. 

 

Bob was/ is a pleasure to deal with as well.

Edited by amped
clarity
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  • 1 month later...

I bought the VTA ST 120 with the cap upgrades, auto-bias board, and Tung sol KT 120's. So far the thing is great, fits my space, and really sounds good with my Khorns.  Happy camper. Thanks for all the input. Just thought I would close out this topic. Take care all.

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19 hours ago, JRS94 said:

I bought the VTA ST 120 with the cap upgrades, auto-bias board, and Tung sol KT 120's. So far the thing is great, fits my space, and really sounds good with my Khorns.  Happy camper. Thanks for all the input. Just thought I would close out this topic. Take care all.

If you got the Russian PIO cap upgrade, it will take at least 100 hours before they sound their best, so be prepared for your amp to sound better over time!

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