DavidR Posted July 22, 2017 Report Share Posted July 22, 2017 I want to bounce this off the AR members. I have the opportunity to get a Bob Latino VTA ST120 tube amp (based off the old Dynaco amps). Some features of the Bob Latino ST120: -The amp is conservatively rated at 60 watts/channel. -The amp has been professionally built, with very low noise levels. -The Sovtek 6550 output tubes are only about two months old - just warmed in! -Includes Russian paper in oil coupling cap upgrades (a $45 upgrade) -Includes Time delay relay circuitry for a 17 second delay before B+ is applied to tubes (a $60 upgrade) -Includes Upgraded heavy duty 3-prong power cord I've been wanting a tube amp and don't want to shell out big $$$ for an Audio Research, McIntosh or Conrad Johnson (even used is crazy money). These ST120's are supposed to be very good tube amps. Now my question is: Will this be powerful enough for the upper end of an AR9 if I'm bi-amping and using my Emotiva SA-250 (400 watts) on the woofers? No, I don't have any AR9's (yet, but am working on it). David Pics of the actual amp attached. Link to comment Share on other sites More sharing options...
Aadams Posted July 22, 2017 Report Share Posted July 22, 2017 From Page 33 of the AR9 Ref Manual Link to comment Share on other sites More sharing options...
DavidR Posted July 22, 2017 Author Report Share Posted July 22, 2017 Thank you very much for pointing that out Aadams. The amp I'd use on the woofers is a Limited Production Ref. amp and is sold out. The bass it produces is superb. I have a 2nd one but using that on another system where it performs very well. I have a pair of AR91's that would work very well with the ST120 so I may go for it anyway and look for a 3rd SA-250 amp. I thought I'd post what I asked the seller and his response: 17 hours ago DavidR said:Will it handle the upper drivers on an Acoustic Research AR9 (8" LMR, 2.5" dome upper mid and .75" tweeter)?4 ohm rated speakers that can dip to 3.2 ohms David, I just queried Bob Latino on your question. His response: "The VTA ST-120 will handle speakers with impedances that drop below 2 ohms. Certain Martin Logan speakers dip below 2 ohms and some are using VTA amps with those. The nice thing about using the ultralinear circuit is that it can drive very complex loads better than most other amp circuits. The AR9 speakers are 87 dB efficient. As long as the room is not too huge and you don't want to play stadium rock music at head banging levels, the ST-120 will drive them fine." Bill Link to comment Share on other sites More sharing options...
ar_pro Posted July 22, 2017 Report Share Posted July 22, 2017 There's also the issue of balancing the outputs of two dissimilar amplifiers - you wouldn't want the upper and lower sections of the AR-9 to be playing at unequal levels. It's been awhile since I've had the opportunity to enjoy biamped AR-9's, but they always seemed their best with muscular solid-state amplifiers that had strong & clean reserves of power to handle the somewhat difficult load of the 9. It's not just the bass that's affected - the upper range really likes robust power as well. I'd bet the big Emotiva amplifier is not only powerful, but dead quiet, and devoid of hum or hiss at any level. Even the best vacuum tube amplifiers would find that difficult to achieve. A pair of SA-250's in vertical bi-amp mode would be an outstanding combination with the AR-9. The ST-120 looks like a nice upgrade of the Stereo 70, with basically twice the power, so it could be a fun experiment if the price is right. At the very least, it would probably match up well with the AR-91. Link to comment Share on other sites More sharing options...
DavidR Posted July 23, 2017 Author Report Share Posted July 23, 2017 I agree that a "muscular solid-state/robust amp" brings out the best in the big AR speakers. The SA-250 doesn't break a sweat driving my 90's or 901_ll. Yeah, I think the amp would match well with the 91's. However. the seller went a bit 'nutty' when I asked him how old the amp was. He did state the output tubes are relatively new. I got this for a response: " David, this is small change for me. After helping you out, I get suspicion. Well..... " I originally asked if he would pick-up the shipping costs. You know, negotiating. He offered to meet me half way (1.5 hour ride for each of us) for $25. I thought that was a great deal. I then asked if he would accept a treasures check so I didn't have to carry a bundle of cash or use PayPal and absorb the 3% fee. He had also suggested I pay Family and Friends which gives me no recourse if he's a no show or something is wrong with the amp. The response left me saying WTF? Happy for him the money is chump change. Link to comment Share on other sites More sharing options...
nefertem Posted July 23, 2017 Report Share Posted July 23, 2017 Hi David I always thought about doing that when I had my tube integrated amps in the 90s though I only have the 93s Link to comment Share on other sites More sharing options...
Aadams Posted July 23, 2017 Report Share Posted July 23, 2017 16 hours ago, DavidR said: The amp I'd use on the woofers is a Limited Production Ref. amp and is sold out. Your SA-250 will be plenty for the AR9. A second SA-250 amp is only going to add 3db of acoustic output. The AR9 manual states that 50 w/ch in a moderately live 3000 Cft room will be adequate for 107db peaks at 1 meter. 400 w/ch will get you approx. 107db peaks at 12ft. or 20db of headroom above 87. Even greater If your room has really low ambient noise. Most pop and rock music only has a 5 to 6db variation in level over the course of a recording. The biamp section of the manual gives a feeling that biamping was offered merely as an option to increase acoustic output and not a way to increase performance quality. The max recommended amp is 400 watts /ch. Page 51 of the Ref manual clearly explains the AR9 operating limits and why 400 watts is the max. Link to comment Share on other sites More sharing options...
DavidR Posted July 23, 2017 Author Report Share Posted July 23, 2017 Thanks again Aadams! That relives me of the search for another amp. Link to comment Share on other sites More sharing options...
AR surround Posted July 23, 2017 Report Share Posted July 23, 2017 18 hours ago, DavidR said: I thought I'd post what I asked the seller and his response: 17 hours ago DavidR said:Will it handle the upper drivers on an Acoustic Research AR9 (8" LMR, 2.5" dome upper mid and .75" tweeter)?4 ohm rated speakers that can dip to 3.2 ohms David, I just queried Bob Latino on your question. His response: "The VTA ST-120 will handle speakers with impedances that drop below 2 ohms. Certain Martin Logan speakers dip below 2 ohms and some are using VTA amps with those. The nice thing about using the ultralinear circuit is that it can drive very complex loads better than most other amp circuits. The AR9 speakers are 87 dB efficient. As long as the room is not too huge and you don't want to play stadium rock music at head banging levels, the ST-120 will drive them fine." Bill What I found when I tried to drive my AR9's with a smaller amplifier was a noticeable compression of the sound at moderately loud levels...nothing anywhere close to head banging levels. Now this issue may have been due to this particular amp, which I would call a middle of the road consumer product. It would be interesting to see how this VTA 60 wpc tube amp would handle the AR9 (not bi-amped) given that it is stable even below a 2 ohm speaker impedance. What I've noticed about speakers driven by very large amplifiers is not so much the ability to play louder, but rather the sense of openness resulting from having so much headroom. Link to comment Share on other sites More sharing options...
frankmarsi Posted July 23, 2017 Report Share Posted July 23, 2017 1 hour ago, AR surround said: What I've noticed about speakers driven by very large amplifiers is not so much the ability to play louder, but rather the sense of openness resulting from having so much headroom. I'm almost grasping this. I think I am, therefore, I am? Link to comment Share on other sites More sharing options...
AR surround Posted July 23, 2017 Report Share Posted July 23, 2017 16 minutes ago, frankmarsi said: ...I think I am, therefore, I am? "Of course you are my bright little star." Link to comment Share on other sites More sharing options...
DavidR Posted July 23, 2017 Author Report Share Posted July 23, 2017 2 hours ago, AR surround said: What I found when I tried to drive my AR9's with a smaller amplifier was a noticeable compression of the sound at moderately loud levels...nothing anywhere close to head banging levels. Now this issue may have been due to this particular amp, which I would call a middle of the road consumer product. It would be interesting to see how this VTA 60 wpc tube amp would handle the AR9 (not bi-amped) given that it is stable even below a 2 ohm speaker impedance. What I've noticed about speakers driven by very large amplifiers is not so much the ability to play louder, but rather the sense of openness resulting from having so much headroom. Quite right. More drivers are damaged by NOT having enough power vs too much power. If a SS amp can't produce the power to send a clean wave/signal the wave gets clipped and that's when damage occurs. I have also found that the class of amp plays a role as well. Link to comment Share on other sites More sharing options...
frankmarsi Posted July 23, 2017 Report Share Posted July 23, 2017 3 hours ago, AR surround said: "Of course you are my bright little star." Borrowing AR surround's crystal ball I feel I know how this post will go. In a few minutes all of the self-proclaimed experts will be here extolling the virtues of low power amps and $40. cartridges. And that all interconnects sound the same as do amplifiers. I'd much rather continue ultra-sonically cleaning another batch of vinyl, afterwards listening to my just rewards. Link to comment Share on other sites More sharing options...
DavidR Posted July 23, 2017 Author Report Share Posted July 23, 2017 All amps do not sound the same nor do pre-amps. Interconnects not so much. Nothing to justify the uber expensive ones or the high priced ones. Cartridges are all different however, some sound like others. Link to comment Share on other sites More sharing options...
frankmarsi Posted July 23, 2017 Report Share Posted July 23, 2017 David, it seems that you’ve misread my sentences, I was being facetious. Have you auditioned many different cables, if so in what price ranges? These components such as amps and inter-connects can be very, very, different from one another though, some here don't know any better and think everything sounds the same when clearly on a good system, the facts and differences speak for them selves if one has the experience in such matters. I have always noticed changes for the better, every time since 1972 and before. Each time I've upgraded from one component to the next, be it cables, amps, speakers, cartridges etc. Before making purchases each time I did read all I could find plus asked other folks and to quality vendors who had first hand information. And certainly of course I trusted my own ears that have years of personal listening experience. Some folks simply ignore reality and defend what they have and spent money on- human nature I guess. What's the expression, a person only sees what they want to see and dismisses the rest? Silly and useless to that individual who thinks there aren't any differences. Example: I was here a number of months ago and some individual decided to mention that his $150.- cartridge was a 'giant-killer' after I was talking about my own $2000. to $4,000. cartridges. I can't imagine some folks with such an inability to understand proven facts and information. Link to comment Share on other sites More sharing options...
AR surround Posted July 24, 2017 Report Share Posted July 24, 2017 2 hours ago, frankmarsi said: David, it seems that you’ve misread my sentences, I was being facetious. Have you auditioned many different cables, if so in what price ranges? These components such as amps and inter-connects can be very, very, different from one another though, some here don't know any better and think everything sounds the same when clearly on a good system, the facts and differences speak for them selves if one has the experience in such matters. I have always noticed changes for the better, every time since 1972 and before. Each time I've upgraded from one component to the next, be it cables, amps, speakers, cartridges etc. Some simply ignore reality and defend what they have and spent money on- human nature I guess. Silly and useless to that individual who thinks there aren't any differences. Example: I was here a number of months ago and some individual decided to mention that his $150.- cartridge was a 'giant-killer' after I was talking about $2000. to $4,000. cartridges. Imagine such inability to understand. I enjoy the challenge of trying to get the most bang for the buck. I'm quite sure that I can haul a wheelbarrow full of money into an audio salon and come home with something better than what I have now. But playing around with the old stuff is a lot more fun. Link to comment Share on other sites More sharing options...
frankmarsi Posted July 24, 2017 Report Share Posted July 24, 2017 On 7/23/2017 at 10:28 PM, AR surround said: I enjoy the challenge of trying to get the most bang for the buck. I'm quite sure that I can haul a wheelbarrow full of money into an audio salon and come home with something better than what I have now. But playing around with the old stuff is a lot more fun. My speakers are 45+years old, my amps are 37 years old, except they were rebuilt 10 years ago, my tonearms are anywhere from 45 to 50+ years old, most of my vinyl is just as old, what's your point defined? My in use cartridges are 1 to 4 years old. One of my RCM's is 10 years old and my ultrasonic cleaning gear is 1 year old. My collection of thousands of vinyl records is anywhere from new release to 50 plus years old. I believe I qualify regarding; "playing around with old stuff". P.S. just finished three hours of listening to some jazz and vintage Ellington on quality vinyl with a Delos cartridge and a Dynavector 505 tonearm. Do I have to throw in the VHS tape of "Shark-Nado" or do I have to take out my departed father's 78RPM shellacs from 1928-31 of Enrico Caruso, clean them up to be considered that I do the same? Link to comment Share on other sites More sharing options...
ra.ra Posted July 24, 2017 Report Share Posted July 24, 2017 3 hours ago, frankmarsi said: I was talking about $2000. to $4,000. cartridges. That was a real knee-slapper. Finally, I am beginning to understand the meaning of "facetious". Thanks. Link to comment Share on other sites More sharing options...
DavidR Posted July 24, 2017 Author Report Share Posted July 24, 2017 I bought the amp and will get it Saturday Link to comment Share on other sites More sharing options...
ra.ra Posted July 24, 2017 Report Share Posted July 24, 2017 Will be interested to hear your comments - - you've got me curious now - - I like the way this amp seems to be a modern upgrade and supercharged version of an old classic - - I'd love to have a 60 wpc tube power amp. I suppose I could look this up myself, but it's hard to tell if this amp can be provided with an optional cage enclosure? Link to comment Share on other sites More sharing options...
DavidR Posted July 24, 2017 Author Report Share Posted July 24, 2017 Bob Latino lives in Sturbridge, MA and sells these as kits. I'm buying this used from the guy who does the wiring for Bob should you want a completed unit. They do have several options but I have never seen one with the old cage as seen on the old Dynaco units. I will inquire. I can also put you in touch with AudioBill who does the builds. Link to comment Share on other sites More sharing options...
ar_pro Posted July 24, 2017 Report Share Posted July 24, 2017 Yay, a new amp - congratulations! Although the folded metal chassis construction looks like it might take a standard Stereo 70 cage, it's possible that the larger transformers and 6550 tubes sit too high, and could hit the top. There might also be a heat issue, as the old Dyna cages had unperforated left & right sides. Looking forward to your review. Link to comment Share on other sites More sharing options...
frankmarsi Posted July 24, 2017 Report Share Posted July 24, 2017 The kit version would be fun to make, have you built an electronic kit before? Link to comment Share on other sites More sharing options...
ra.ra Posted July 24, 2017 Report Share Posted July 24, 2017 Re: cage, see note 2 - - - I found this on Bob's ebay listing for the 120 kit version. Link to comment Share on other sites More sharing options...
frankmarsi Posted July 25, 2017 Report Share Posted July 25, 2017 DavidR, check this out, a gage for the ST-70, it might fit according to manufacturer's post. Where and when would you find one of these? http://www.ebay.com/itm/Dynaco-ST-70-Tube-Amplifier-Top-Cover-Cage-/152603453153?hash=item2387dfe6e1:g:jlQAAOSwgv5ZRmZl Link to comment Share on other sites More sharing options...
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