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    Comparing my VTA ST-120 with my McIntosh MC275

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    DrewK

    Posts : 7
    Join date : 2013-12-06

    Comparing my VTA ST-120 with my McIntosh MC275

    Post by DrewK on Fri Dec 06, 2013 1:28 pm

    Last year I picked up a used McIntosh MC275 Series V off Audiogon for my main system. I have always been a tube amp lover for may years. After playing the Mac for over a year in my main system, I was looking for another tube amp for my smaller system downstairs which presently uses an older Pioneer receiver. When we have a party or friends over we mostly use the downstairs playroom. The kids are gone and no one but adults touch my gear. After looking around the net, I came upon the VTA ST-70 and ST-120 kit amps on the Tubes4hifi web site. I am fairly handy and had built some tube kits in the '60's. I sent Bob Latino an Email with a few questions. Within an hour an Email came back with detailed answers to my questions about cap upgrades and the VTA stepped attenuator. He even gave me his phone number in case I wanted to talk by phone which was nice. To make a long story short I ordered his VTA ST-120 amp kit without tubes but with both of the capacitor upgrades and the VTA stepped attenuator. I paid with Paypal that night and the very next day (a Tuesday) received notification that the kit had been shipped. I received the kit the very next day in NY. It was very well packed. I checked all the parts against the parts list that Bob provides and everything was there. I brought everything to my workroom. It would have to stay there until Saturday when I would have time to work on the kit.

    On Saturday I started the assembly and found the manual to be very well written with good detail. The two photos that Bob sends along were really helpful too. Step by step the amp just came together. The only minor problem I had was the assembly of the supplementary cap module. Nothing wrong with the instructions, it just seemed a little tedious try to hold the cap with one hand and solder with the other. I put in about 6 hours on Saturday and another 6 or 7 hours on Sunday. By Sunday night I was done. I placed the three driver tubes in the amp and connected my old KLH 6 speakers and my CD player to the inputs. Flipped the switch on the amp and all the driver tubes lit up. Shut the amp down and placed the two left channel Genalex Gold Lion KT88's that I had bought separately and an old Stromberg Carlson 5AR4 rectifier that I had laying in a box of tubes. Everything lit up and I biased the left channel. I walked over to the left speaker and put my ear to the grille cloth and heard a barely audible hiss. A foot away from the speaker I could hear nothing. Shut the amp off. I inserted the right KT88's turned the amp on and biased the right channel. No blown fuses, no noise, nothing. Turned the Oppo CD player on with one of my Steely Dan SACD's. Out of the silence came Steely Dan sounding MUCH better than what I got with the old Pioneer receiver and through 40+ year KLH old speakers.

    The next weekend I brought the amp upstairs to try in my big system which has B&W 683 speakers and the Mac MC275 amp. I first played the Mac MC275 with my Cary SLP 03 preamp (another Audiogon buy) to remember the sound of the amp. I then swapped in the VTA ST-120 but bypassed the preamp and used just the stepped attenuator for volume control. It immediately sounded different and the difference was in wider soundstaging. The sound was more "holographic" on the VTA ST-120. The 120 also had a cleaner and more extended top end. It made my Mac sound kind of "dull" by comparison. Maybe the bypassing of the preamp gives the VTA amp an advantage? The gain of the amps was very similar and the ST-120 at its rated 60 WPC sounded just as strong as the Mac's 75 WPC. Later the next day, I had an audio friend come over and listen. He brought over some his vocal jazz SACD's. He was also amazed that the little VTA ST-120 sounded as good as it did considering that Mac costs about 3 to 4 times the price of the 120. He also agreed that the top end was better on the 120. Now I am in a quandry? I don't know now whether to keep the MC275 in my main system or replace it with VTA ST-120 and bring the Mac downstairs? For the meantime I am going to keep the 120 in my main system and let it break in completely. I will also try the ST-120 through the Cary preamp when I have the time. Bob mentioned that if I turn the attenuator all the way clockwise there is no attenuation and the audio signal passes from the input jacks directly to the input circuit. In a month or two I will have to bring one of them downstairs. DrewK

    sKiZo

    Posts : 1312
    Join date : 2013-04-01
    Location : Michigan USA

    Re: Comparing my VTA ST-120 with my McIntosh MC275

    Post by sKiZo on Fri Dec 06, 2013 2:54 pm

    Maybe an apples and oranges kind of thing, but I also swapped out from a McIntosh amp to the ST120 and was really impressed with the difference. I'm hearing a LOT of music that wasn't there before. Flipped thru several tubes sets before I "settled" for what I'm currently using.

    - TungSol KT120 x4
    - Telefunken ECC82 center
    - Gulbransen (Amperex Holland) side drivers
    - Amperex Holland GZ34

    Apples = the ST120 with a few minor mods, including dual volume controls (I find the balance option handy with my weird room) and larger chokes.

    Oranges = a McIntosh MC2205 solid state amplifier purchased new in 1980. The "60wpc" quoted for the Latino amp holds it's own against the 200wpc of the Big Mac. Granted, the main reason I was looking for a replacement is that the Mac was getting long in the tooth and due for some serious TLC.

    I was originally switching back and forth to confirm my preference, and the MC2205 has been basically collecting dust and taking up space for now. Latest plans are to drag it down to storage so I can free up the cabinet space for a Carver C4000 pre that should be ready shortly after a recap and upgrade. I have my suspicions that once the MC2205 is done, I may just flip it out of here ... with the provision that the buyer drag it back up out of the basement ...

    Kudos to Bob and Co. for an outstanding product!

    ArlanB

    Posts : 52
    Join date : 2011-01-23
    Age : 69
    Location : Santa Cruz, California

    Re: Comparing my VTA ST-120 with my McIntosh MC275

    Post by ArlanB on Fri Dec 06, 2013 6:07 pm

    DrewK,  

    I think that you will eventually settle with the VTA ST-120.  I have one of Bob's first kits that I built over 5 years ago.  Mine is an unmodified kit with stock caps and uses the higher gain driver board.  My system consists of a PAT4 preamp (recapped), the VTA ST-120 into ESS Heil AMT10b speakers and I could not be happier.  Hardest thing to do was to assemble a set of tubes that perform to my liking.  Presently I use Mullard CV 4024's, Penta Labs KT88SC, and a Sovtek 5AR4.  My listening is 99% vinyl as the music source.  I do have CD and tuner sources, however I find that I almost never switch from vinyl.  I think that you have made a wise choice and will not regret it.

    ArlanB

    tubes4hifi
    Admin

    Posts : 1292
    Join date : 2008-11-30

    Re: Comparing my VTA ST-120 with my McIntosh MC275

    Post by tubes4hifi on Sat Dec 07, 2013 3:17 pm

    Drew,
    your experience is very similar to hundreds of comments I've received over the past few years from people hearing our VTA70 and VTA120 amps for the first time.
    It seems like a simple amp based on a fifty year old design, but a little modern finesse of the actual electronics circuits puts these amps in SERIOUS competition for current mainstream audiophile equipment selling for well over $5000.

    DrewK

    Posts : 7
    Join date : 2013-12-06

    Re: Comparing my VTA ST-120 with my McIntosh MC275

    Post by DrewK on Sat Dec 07, 2013 6:59 pm

    OK - so I ran the VTA ST-120 today through my Cary SLP 03 with the stepped attenuator on the 120 turned all the way clockwise. The sound was virtually the same as with the stepped attenuator in the circuit. The ST-120's holographic sound stage was still there and the better top end extension over the Mac MC275 was also still there. I swapped the Mac back in and the slightly muted top end came back. The Mac is very good but the placement of instruments in the sound stage is not quite as good as the ST-120's.  Round 2 (VTA ST-120 vs Mac MC275) with using my Cary preamp with the ST-120 also goes to the ST-120. DrewK

    hawaii.ken

    Posts : 157
    Join date : 2012-01-31

    Re: Comparing my VTA ST-120 with my McIntosh MC275

    Post by hawaii.ken on Sun Dec 08, 2013 1:55 am

    DrewK wrote:Now I am in a quandry? I don't know now whether to keep the MC275 in my main system or replace it with VTA ST-120 and bring the Mac downstairs? For the meantime I am going to keep the 120 in my main system and let it break in completely. I will also try the ST-120 through the Cary preamp when I have the time. Bob mentioned that if I turn the attenuator all the way clockwise there is no attenuation and the audio signal passes from the input jacks directly to the input circuit. In a month or two I will have to bring one of them downstairs. DrewK
    Depending on the condition of your MC275, you can get $3000 - $5000 if you sell it on evilBay.

    Use the proceeds of the sale to buy a pair of M-125 Monoblocks for use on your main system.

    If there is money still left after you get the M-125's think about spending it on a vinyl playback system (turntable + PH-16 phono preamp).

    Just food for thought.

    Laminarman

    Posts : 110
    Join date : 2009-12-30

    Re: Comparing my VTA ST-120 with my McIntosh MC275

    Post by Laminarman on Sun Dec 08, 2013 11:14 am

    hawaii.ken wrote:
    DrewK wrote:Now I am in a quandry? I don't know now whether to keep the MC275 in my main system or replace it with VTA ST-120 and bring the Mac downstairs? For the meantime I am going to keep the 120 in my main system and let it break in completely. I will also try the ST-120 through the Cary preamp when I have the time. Bob mentioned that if I turn the attenuator all the way clockwise there is no attenuation and the audio signal passes from the input jacks directly to the input circuit. In a month or two I will have to bring one of them downstairs. DrewK
    Depending on the condition of your MC275, you can get $3000 - $5000 if you sell it on evilBay.

    Use the proceeds of the sale to buy a pair of M-125 Monoblocks for use on your main system.

    If there is money still left after you get the M-125's think about spending it on a vinyl playback system (turntable + PH-16 phono preamp).

    Just food for thought.
    Just saw a 30 year old MC275 at Audio Classics being put on the shelf a few weeks back, condition B1 (although it looked mint to my eyes and was wrapped in plastic.) I think they had it priced at $3,999.

    tubes4hifi
    Admin

    Posts : 1292
    Join date : 2008-11-30

    Re: Comparing my VTA ST-120 with my McIntosh MC275

    Post by tubes4hifi on Mon Dec 09, 2013 12:31 pm

    nice to know someone else can verify what I've been saying for 20+ years, I give value for the money, and my stuff sounds better than other stuff you can buy for 4X the price!
    Also of course, much thanks to Bob for figuring this out 7-8 years ago and selling a ton more of these amps to you all, and for putting up this forum to share information!

    DrewK

    Posts : 7
    Join date : 2013-12-06

    Re: Comparing my VTA ST-120 with my McIntosh MC275

    Post by DrewK on Tue Dec 10, 2013 12:01 pm

    Ok so last night I run the McIntosh MC275 against the VTA ST-120 but I had the ST-120 in triode mode. Guess what? They sound of the two amps is pretty close now. Of course now the Mac now has a power advantage because the ST-120 loses a little power when you place it in the triode mode. The ST-120 now has a top end pretty similar to the Mac. Just as Bob said vocals and acoustic jazz sound nice in triode. I also played some of my older rock stuff ... Led Zeppelin, The Doors etc. For any kind of rock music though the pentode ultralinear mode of the ST-120 gives a better top end than the Mac (cymbals and other higher pitched tones). My feeling is that the ST-120 is a better amp for rock music. DrewK

    zx

    Posts : 194
    Join date : 2011-08-05

    Re: Comparing my VTA ST-120 with my McIntosh MC275

    Post by zx on Tue Dec 10, 2013 4:38 pm

    DrewK.....
    Thanks for you thoughts on the MC275............sounds right on the money....some say thay can sound dark.....there output tranfourmers have cathiod feedback.....Only ARC use this feedback type setup....But for me there tube amps an PreAmps..... sound like SS............I have tride to like there amps.....just cant get .....SS sounding tubes...........i gess you have to have some thing for eveyone!
    I like OnS GE6550s in the 275....not the KT88..........but have heard the KT88 sound vary good in the 275s on speakers like the B&W 802D..........an Apogees Ribbons....Most have not spent time with any of the MC tube amps.........I sold Mcintosh in the 89-90s....MC1000 were great for SS Amps....vary tubey sounding ...

    Have fun..........

    thanks for the site Bob......

    Sprags

    Posts : 123
    Join date : 2013-02-27

    Re: Comparing my VTA ST-120 with my McIntosh MC275

    Post by Sprags on Sat Dec 14, 2013 2:54 am

    I found a Cary SLP03 listed on Audiogon that I'm going to go listen to next weekend. The seller agreed to hold it for me. It's a demo unit that's gotten little listening time at the store. He also agreed to a 2 week trial to let me bring it home and listen to with my VTA-120. I have Polk Audio LSiM703's. After reading DrewK's post it really got me interested in the Cary preamp. I searched for reviews and it seems there's a mix. I imagine that if you compare it to an $8000 preamp there will be a difference but since I'm getting it for 1/8 the price if it sounds 98% as good I'll be happy.

    bcinnamon

    Posts : 26
    Join date : 2011-05-07

    Re: Comparing my VTA ST-120 with my McIntosh MC275

    Post by bcinnamon on Sat Dec 14, 2013 8:56 pm

    I have basically the same setup: an ST-120 and an MC-275. Unfortunately, I cannot compare them directly since they are in different rooms with different speakers. Someday I will make an A/B power amp switch. I can say that the sound from both is terrific, and cranks up as loud as I want. The one non-acoustic difference (I'm an energy nut) is that, at comparable volume levels, the ST-120s draw about 235 watts whereas the Mac draws about 150 watts.

    kevinmi

    Posts : 54
    Join date : 2009-11-17

    Re: Comparing my VTA ST-120 with my McIntosh MC275

    Post by kevinmi on Sun Dec 15, 2013 9:53 am

    I am using my ST120 with a Cary SLP98P F1 preamp and I think it is a match made in Heaven. I listen to 90% vinyl. When my friends stop by and I play an album followed by a cd, they always say the vinyl sounds better!

    DrewK

    Posts : 7
    Join date : 2013-12-06

    Re: Comparing my VTA ST-120 with my McIntosh MC275

    Post by DrewK on Mon Jun 16, 2014 6:38 pm

    Sorry to drag up my old thread here but I wound up keeping the VTA ST-120 in my upstairs system and I put the Mac MC275 in my playroom downstairs. It still boggles my mind that I like the sound from the much less expensive ST-120 better than the Mac .. The Mac just seems to have too soft a top end at least for the my speakers. The ST-120 is not bright at all on the top end but it just seems to have more top end extension. Oh yeah - one other thing .. Just for the hell of it I pulled the four Russian PIO caps from the board and temporarily installed four Auricaps in their place. The sound changed and it wasn't for the good. The soundstage collapsed a little and the amp just did not sound as good as with the Russian PIO caps that Bob provided with the kit. I know you are supposed to let new capacitors break in a little but even after 50 hours or so with the Auricaps I missed the sound of the Russian caps so I pulled the Auricaps and reinstalled the same four Russian PIO caps. Yes, the old sound was back! Even my tin eared wife could hear the difference after I reinstalled the Russian caps. DrewK

    audiobill

    Posts : 270
    Join date : 2014-03-13
    Location : Philadelphia

    Re: Comparing my VTA ST-120 with my McIntosh MC275

    Post by audiobill on Mon Jun 16, 2014 7:51 pm

    Try the PIOs in the Mac!

    corndog71

    Posts : 454
    Join date : 2013-03-19
    Location : It can get windy here

    Re: Comparing my VTA ST-120 with my McIntosh MC275

    Post by corndog71 on Mon Jun 16, 2014 10:45 pm

    Maybe the Mac needs some new tubes.

    zx

    Posts : 194
    Join date : 2011-08-05

    Re: Comparing my VTA ST-120 with my McIntosh MC275

    Post by zx on Tue Jun 17, 2014 8:51 am

    Funny you keep thinking it the tubes...............i have a quad of GE6550s that are 50years old
    must have over 1000hr on them.............sound better than most 6550s i have found today....hehe....Sold a lot of Mcintoshs....it a littel on the Dark side...


    thanks for the sete Bob...........

    corndog71

    Posts : 454
    Join date : 2013-03-19
    Location : It can get windy here

    Re: Comparing my VTA ST-120 with my McIntosh MC275

    Post by corndog71 on Tue Jun 17, 2014 10:21 am

    The few times I've heard McIntosh gear it has sounded very good to me. Of course how the stereo is set up and what speakers they were matched with make a difference. I've heard Mac gear driving Martin Logans, top of the line Monitor Audio and Klipsch speakers and the sound was excellent. Granted this was all solid state gear. I also heard Mac tubes driving Mac speakers which also sounded very good to me. Ultimately, McIntosh gear is not for me. Too expensive. Plus, I really love my ST120.

    I only suggested replacing tubes because depending on a list of reasons different tubes might make the amp sound better. They will eventually fail and not everyone has such good luck with nos tubes.

    zx

    Posts : 194
    Join date : 2011-08-05

    Re: Comparing my VTA ST-120 with my McIntosh MC275

    Post by zx on Tue Jun 17, 2014 11:15 am

    So you say......I really love my ST120.

    Well yes....i think from what most here say..... these guys have got these tubeamps sounding right!
    I do not have anything but Dynaco oldstock MK3s.....an i have done some so called upgreades....an have found that if you put your hands in the.... DIY mixs......it sound better....well too me
    But you may have a leg up on most here with your all Aluminum chasse......
    While Aluminum dose not block RF as well as steel.....it has a sound of it owne....
    I have owned more than one peace of old hhscott & Eico tube grear......299a,299c,355 thay like Eico used all Aluminum chasse....
    I now have a hhscott 355 tube tunerpreamp that is so sweet....it kills most any other preamp..... know matter how much $$.....tube are SS......it uses one 12AU or 12AT at it output...an has the left & right ch in the one tube...Nuts right....this has to add to the sound...
    Have fun with tubes..............Hehe

    Thanks for the site Bob..................

    DrewK

    Posts : 7
    Join date : 2013-12-06

    Re: Comparing my VTA ST-120 with my McIntosh MC275

    Post by DrewK on Tue Jun 17, 2014 4:55 pm

    corndog71 wrote:Maybe the Mac needs some new tubes.

    This was a used Mac MC275 that I picked up on Audiogon. It was in excellent condition and wasn't used that much. I had a friend with a tube tester test both the 4 KT88 tubes and the 7 driver tubes on the Mac. They all tested good. When I have time though I may substitute some of the Mac's driver tubes with some others that I have here to see if that helps the Mac any. DrewK

    zx

    Posts : 194
    Join date : 2011-08-05

    Re: Comparing my VTA ST-120 with my McIntosh MC275

    Post by zx on Tue Jun 17, 2014 5:33 pm

    Thanks for more info on your MC275.......i have found some 6550s can open the 275 up a littel..
    I like the sound of the Mc....as you say you do.....with the right speaker in a live room...the sound can be vary forgivening...Horns can sound vary sweet with the 275 an thats were i have seen them kik butt..all the older Mc amps were made for PA horn type setups back in the day...Mc275 sold for what back in the day........less than $300.... If you dont know the Mc output trans are diff than most.....the cathoids have feedback with it owne winding .....this flotes the output tubes.... Bobs amps dont do this....like most all other tube amps.....the cathoids are grounded....an the output trans on the Mc are poted....about 25lb ea...Like lead...you get no ringing like unpoted trans.....if you pull the feedback winding out an set the cathiods up like Bob amps ...the 275 well open up.....how ever I WOULD NOT DO THIS MY SELF!.....just saying... other have an the amp worket fine.....but i would just sale the amp an get one of minny others tube amp .....
    Best sounding  tube Amp thay ever made was the littel MC225..some say..7591 output tube like used in the hhscott of the day......have fun with tubes


    Thanks for the site Bob.........

    mantha3

    Posts : 298
    Join date : 2010-11-10

    Re: Comparing my VTA ST-120 with my McIntosh MC275

    Post by mantha3 on Tue Jun 17, 2014 5:52 pm

    Somewhat similar experience for me... I own a pair of MC75 60th anniversary amps made in 2009. I had some buyers remorse when I got them to replace my ST120.

    I have my MC75s ran with a DCB1 preamp I built. This is a Nelson Pass B1 buffer that has a nice regulated power supply. Check out DCB1 on DIYAUDIO.com. The passive attenuator into a buffer out to the MC75s really got these amps going well. I prefer this over other McIntosh Preamps I've listened to. You probably can find something to get you Mac amp to sing.

    Try in you ST120 some Jensen Copper In Oil coupling caps. Unreal good.


    mantha3

    Posts : 298
    Join date : 2010-11-10

    Re: Comparing my VTA ST-120 with my McIntosh MC275

    Post by mantha3 on Tue Jun 17, 2014 5:55 pm

    PS - DO you like the Bass of the ST120 over the Mc275.  The ST120 I have I like the midrange a tad better and the overall tube sound better...  The two MC75s I have I do like the bass but the bass has a slightly more solid state type of sound as compared to the ST-120.  Both excellent and both I love...  Just a bit different and hard to describe the difference for me.  

    I could not sell my ST120 when I got the MC75s...  Was planning to but could not bring myself to do it.  Glad I didn't!!!!

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