Bob Latino's VTA ST-120

Good afternoon everyone... I hope all of you are having a good day and safe.

I am new here and I'm finally getting back to building tube amplifiers like I used to years ago.

A few weeks ago I spoke to Mr. Bob Latino in an email about his VTA ST-120 and then changed my mind when I found that he had a VTA M-125.
After a few weeks of deep thinking I really like the VTA M-125 but have again changed my mind back to the VTA ST-120. I have to say that amp looks sweet !! and it’s a beautiful piece of work and craftsmanship.
I also like that the amp has been beefed up to 60w per channel and has been modified/updated to get the very best out of those beautiful gorgeous tubes and massive iron transformers.

I plan to buy one of these beauties hopefully in a few months when I get the funds together and saved plus I definitely want to build this kit on my own. I’m just one of those kind of guys that just loves perfectly wired cable management. lol

Have a good day and clear skies everyone and stay safe.

I have a VTA  ST-120.   It's a great amp.  Sounds great.   If I had to do it again,  I would buy the M-125s for a few reasons.  First,  wiring the ST-120 is a little congested.   There is a lot of stuff packed in that chassis.   The M-125s have more open space,  making it a little easier to assemble and debug.  Secondly, if you run the M-125s with two output / power tubes per side,  you basically have an ST-120  with an extra rectifier tube.   The ST-120s have a reputation for being hard on the rectifier tubes.   Either way, for the rectifiers I would go for a Tung Sol 5AR4 from Jim McShane,  or Weber Copper Top solid state rectifiers.

Hops wrote:I have a VTA  ST-120.   It's a great amp.  Sounds great.   If I had to do it again,  I would buy the M-125s for a few reasons.  First,  wiring the ST-120 is a little congested.   There is a lot of stuff packed in that chassis.   The M-125s have more open space,  making it a little easier to assemble and debug.  Secondly, if you run the M-125s with two driver tubes per side,  you basically have an ST-120  with an extra rectifier tube.   The ST-120s have a reputation for being hard on the rectifier tubes.   Either way, for the rectifiers I would go for a Tung Sol 5AR4 from Jim McShane,  or Weber Copper Top solid state rectifiers.

I plan to buy the kit without the tubs and the Tung Sol 5AR4 rectifier is definitely on my shortlist :-)
Also the KT-88 or KT-120 Output tubes. Im Also thinking of the Telefunken ECC82 / 12AU7 for the driver section.

Tom, hello; talk to Jim as Hops suggests about the tubes. He has given me some great advice and I always follow his suggestions before I get tubes from him. Always totally satisfied. And you will love that VTA ST120.
I like the GZ34 rect, KT88 and the 12BH7AEH in the center drive. Dale

I love my ST-120 more and more every day. Currently building a SP14 pre amp.



SP-14 main board

smoorenc wrote:I love my ST-120 more and more every day. Currently building a SP14 pre amp.



SP-14 main board

Wow..... That is SWEET !!!

Looks beautiful! Still loving my ST-70 with KT-66's. Variac should extend tube life. Have contemplated building a 120 but its a want not a need!

Hey Guys/Gals..... I have to make a correction.
I said (in my post comment above) that I was going to use KT120 power output tubes in the VTA St-120.... Just did some looks on specs and I do not believe I will gain anything over the KT88/6550. In fact it may put to much of a load on the transformer and other components without any gain in power.
I need to see the schematic and documents on the transformer (and other components) to see what is the nominal current and voltage output is to see what the load is on the amp.
Rule of thumb..... It's never a good idea to put to much load or stress on your amp just to gain a few watts !!

I do not have the money to tube roll. Bob Latino and Jim McShane both recommend the Sovtek 6550 tubes for sound , price , and reliability. I have the Sovtek's, and my ST-120 sounds amazing to me. The three small tubes are supposed to have the most effect upon sound anyway. I bought my tubeset from Bob --- only thing I would do different is get a Tung Sol rectifier, but he supplied the 6550's and NOS RCA Driver tubes ( 5963s I think ). If you want an improvement in sound. , ask McShane what he recommends for the center small tube. I will admit that if I had money to burn, I would get the KT-120s. But I don't.

I'm using KT120's in my ST120.

After reading up, the consensus was that 6550's were more musical than the KT88's. I ended up with TungSol (Russian) 6550's. I thought they sounded great. I now have KT120's- I think they have more everything than the TS6550's. I had some KT88EH's but thought the 6550's were better. I keep the attenuator (volume) around 12-2 o'clock. IIRC, the 120's weren't much more than the Gold Lion KT88's either (from Mc Shane)

I installed auto bias on my amp (painful journey) and this has delay so, I switched out the TungSol 5AR4 with a Weber WS-1t rectifier. This makes less heat and frees up about 17v in heater voltage. Auto bias running fine now BTW. I use the NOS 5963's from Bob on the outside and a Brimar ECC82 in the middle. I got the PIO cap upgrade as well. I did the "yellow sheet" mod as well (before I got the s/s). I love my ST120. There's lots of info on the forum and if I recall, Bob runs KT120's in his amp.

Sorry if I said too much but enjoy the journey!

Do the speaker posts on the VTA ST120 accept 12 gauge bare wire or do you need banana posts to go that big?

I am using 12 AWG wire on mine. Seems to be overkill. I did solder the tips to prevent fraying / shorts. Most websites say you get better contact WITHOUT soldering the tips, but the soldered tips seem to work fine. I used JSC Wire Speaker Wire Cable 12 AWG Clear 100 ft. USA from Parts Express, because JSC is made in the USA. Seems to work well. I had to cut it down to get into the spring clips of my subwoofer, but thats an issue with the subwoofer, not the VTA-120

Hops wrote:I am using 12 AWG wire on mine.  Seems to be overkill.  I did solder the tips to prevent fraying / shorts.    Most websites say you get better contact WITHOUT soldering the tips,  but the soldered tips seem to work fine.   I used JSC Wire Speaker Wire Cable 12 AWG Clear 100 ft. USA from Parts Express, because JSC is made in the USA.  Seems to work well.   I had to cut it down to get into the spring clips of my subwoofer, but thats an issue with the subwoofer, not the VTA-120

Awesome, I just ordered an ST120 and I want to get my ducks in a row for when the amp arrives and make sure I don't need to get banana clips for the existing wires I use.

Build completed in the last few days. M-125 is my choice.

Hops -- what is the distance from amp to Speakers?

I think my cable runs are about 30 feet--- small room, sub satellite system with the satellite system with the satellites mounted about 6 ft up the wall across from the amp. Wires wrap around about 2 & 1/2 walls. Both the 12 gage zip cord and the VTA-120 are overkill -- built my daughter a ST-35 from dynakit parts ( great amp, highly recommended) and the ST-35 was plenty loud in the system. I really like both the VTA-120 and the Dynakit Parts ST-35--- I don't think you can go wrong with either Tubes4hifi or Dynakit Parts.

Still enjoying my ST-70 for over 8 years now and running great. With the room treatments and dialing in speaker placement, the imaging is outstanding. The addition of Anticables 3.1 is a vast improvement over the previous Libtec cables. The room "opened up", can surely tell the differences in a quality recording. Highly recommend these. Check out Petra Magoni Musica Nuda "Day Tripper" if you want imaging.