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JRS94

Bob Latino LTA ST120 OR QS MID MONO'S

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Any opinion / experience between these two amps? Both look like they'd be fine with my modded khorns. Will I lose bass going from solid state to tubes?

Thanks again

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I have a Latino  VTA ST120. It sounds great and sound characteristics can be tweaked a bit by tube rolling. I don't have Khorns BTW.

 

You could search or pose the question on that forum:  http://dynacotubeaudio.forumotion.com

 

 

Edited by amped
typo

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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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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.

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I'm going to have it built with AB. Just had to research a little more. Bob says 3 weeks from receipt of my payment. Thanks Kevinmi and Amped!

Joe 

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2 hours ago, JRS94 said:

I'm going to have it built with AB. Just had to research a little more. Bob says 3 weeks from receipt of my payment. Thanks Kevinmi and Amped!

Joe 


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

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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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Between these two amp manufacturers, and the amps you pose, I feel that the Quick Silver Mid Monos will easily be the smartest and best choice.

 

The Stereo amp has to share a Power Supply, on what is a CROWDED chassis, and so, its performance is compromised, and there is little room to make improvements.

 

In a PAIR of mono blocks, there is no interaction of the power supply,, between two channels.  Monoblocks are INHERENTLY superior, if both amps were built at the same basic level, which I THINK these are !

 

This also applies in the McIntosh line.  The mono MC-60s, with chassis-room for DUAL 5U4G rectifiers, easily outperforms the MC- 275, and the H.K. Citation 2.

 

The Latino stereo amp uses a PC board, and the QS amp is all point-to-point wired.  No contest, the later, using REAL wire, as QS does,  is superior. 

 

( I have had Klipsch using people in Q4/2019 augmenting LATINO ST70 PC boards with REAL wire, and its always an improvement.  See photos, and testimony  below. )

 

Also, there is less field interaction between parts, in a pair of monoblocks, because the parts positioning is not as crowded together.

 

Both amps can be parts upgraded, but the QS, being a monoblock - will be spacious underneath, and thus, easier to work on.

 

The Latino amp is certainly an OK product, but the QS, in my opinion, is what I would suggest between these two. 

 

The QS uses 12AX7 and a 6922 ( 6DJ8) as front end triode tubes, both are LINEAR and excellent choices. 

 

You get a lot of responses from the Latino amp owners, because its a popular inexpensive amp, and possibly, more widely owned by Forum Members. 

 

The QS is very clearly to me the best choice, on a from-scratch start basis,  for the above reasons as mentioned.

 

Have fun.

 

Jeff Medwin

 

 

342142773_Board400percent-PLATEandDC.thumb.jpg.e914e7abd8595c38facf47494e3d59eb.jpg

 

Pins 6 to 9, denoted above is a direct couple of the entire music signal, from the plate of the pentode input stage, to the grid of the phase splitter middle stage.

 

1804712216_Pins6and9rewiredfromRaedited2.thumb.jpg.f63d1ac042472a1a74e2fcfdef777590.jpg

 

         The two changes shown above ( Ra and wire) produce a greater positive audio performance benefit, with less cost, than any possible tube rolling can.

 

                                                                                                         * * * * * * * * * * * * * * * * * * * * * * * * * *  *

 

Mr. Medwin,
 
I think you're on to something here.
 
I bought the resistors from Mr. Percy (and some solder) and received the package today. I installed the resistors.
 
The first thing I noticed was a fuller upper bass and lower mid-range which is always welcome. I also noticed what sounded like a somewhat rolled-off high end, something I was not expecting nor did I want. But I quickly realized that what I was hearing was not rolled off highs but better separation of the high frequencies. I played a song that usually had a convoluted high end and immediately noticed better imaging of cymbals, voice and guitar. A song that I had grown tired of was once again a pleasure to listen to! Then I thought I'd try some piano.
 
In my experience, and I think for others also, piano is one of the hardest instruments to reproduce well. Even when other instruments sound bright and full, piano can be muddy. I have made some great sound improvements by upgrading capacitors and tubes, but haven't been able to make significant strides into improving my system's piano reproducing abilities. Your resistor modification has made a noticeable improvement in piano playback. That initial roll-off I thought I was hearing at first is actually an improvement in the high end, and is what I think, making the piano really stand out. Even though I thought I was getting roll-off, the piano sounds brighter! I have to keep pausing from typing this because I keep hearing information that just wasn't there before.
 
I would like to hear a more in-depth explanation of what is going on here. I have a basic understanding of how tubes work, but I'd like to know more of when you say you are hearing the tube and the resistor. Overall, I am happy I made the mod and and grateful to you for suggesting it. My only regret is that the resistors didn't fit on top of the circuit board, I had to mount them underneath. I have paid much more for much less improvement.
 
I'm going to start a new thread soon in the technical modifications section where hopefully you'll explain this all to us in a lot more detail

 

                                                                       * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * 

 

Please note, the above comments pertain JUST to the replacement and upgrading of the Ra ( resistor anode / or resistor plate ). This Klipsch owner's meticulous  soldering - wire augmentation of the Latino ST-70 PC board ( second photo) , to a key circuit area, (under 2 inches per channel ), produced a similarly-effective positive result. 

 

Later Latino PC boards are better made, but they are never truly a substitute for what is possible, performance-wise with higher quality, really good wiring

 

STEP TWO...... lies ahead ,  additional resistor upgrades, which should be lovely, so I expect, for him to hear. 

STEP THREE....is proprietary, some unique final B+ filtering, right at or on the front-end tube. virtually zero lead length, the final " touch " .

 

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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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