OpenTube

DIY Classic Tube Amplifier – Dynaco / VTA ST-120 Review

Audio Nautica

31,977 views

There's an undeniable magic in the sound of vintage tube amplifiers, but they can definitely be a bit tricky! Enter the VTA ST-120 Amplifier - your gateway to a brand new classic tube amp, available as a kit or fully assembled. Inspired by the legendary Dynaco ST-70 from 1959, this amp features some welcome modern enhancements. With the powerful KT-150 tubes I’ve installed, it delivers an incredible punch! And the sound? Fantastic!

Kit is available here: http://www.tubes4hifi.com/amps.htm#ST120

Don't forget to hit that SUBSCRIBE button!
You can also support my content creation journey on Patreon: patreon.com/audionautica, or show some love with a Super Thanks! And be sure to check out my Watchmaking channel: @watchout9213

20 Comments

@cletusberkeley9441 3 years ago (edited)

Proud owner of VTA ST-120 since 2018, assembled it myself, absolutely love it. Use it to drive my 20-year old Altec A7 VOTT, also built by me. Gold Lion KT-88s on-board and now, as of last week, an auto-bias board.

@TheCharlesAtoz 3 years ago

I've watched two of your videos, and I have to say I am thoroughly blown away that we can have this kind of hifi gear for reasonable prices.

@swinde 4 years ago

In the original Dynaco designs, the octal sockets were there to connect a preamp directly. It was carried over from the older mono days. The Dynakit PAM1 had this cable that used the socket. The Dynakit Mark III and Mark IV also had this feature. There were monoblocks.

@kelvinjinxd 3 years ago

What a gorgeous space heater!

@dalemurray655 4 years ago

I've had my VTA ST120 for several years now and quite pleased.
It was the first electronics kit I've ever purchased and found it quite reasonable to complete.

@1cookgs 3 months ago

Thank you for this excellent video. I enjoyed it very much.

@Kastlrock 4 years ago

I just got my st-120 kit delivered today

@andrewhenderson9474 1 year ago

Great Video. New Subscriber from Australia

@dhelton40 3 years ago

The socket for the preamp power is really dated, but it provides test points for power and bias. In the 1960's many of these were installed in custom cabinets/consoles. It was common to use the B plus and filiment supply from the amplifier to power the preamp. Today, most will agree that bringing high voltage outside the amplifier is not very safe. I would build this with access to the 4 & 8 ohm speaker taps, you never know which you will need.

@Ab20222 4 years ago

Awesome review. Does the amp support KT150 or KT170?

@robertseely3286 2 years ago

Nice, very nice, I built the VTA 70 version and run KT88s. I added the yellow sheet diode mod to my GZ34, I'll see what happens when we have a strom that creates a rapid restart. I really enjoy the 70, I grew up with dynacos because I was not rich so the tube sound is what I still want to hear. Thanks for great video! BTW, I run mine on a variac because the transformers are wound for 117 VAC but voltage here can go to123VAC (hello red plate)!

@SteveL-RSR 4 years ago

Nice job mate. Just curious as to what speakers you are running. Cheers.

@JC.LC. 4 years ago

I have the VTA ST70 Amp. It's very good, I recommend replacing the tube rectifier for a solid state if you want better bass from the Amp.

@tangoalpha8381 3 years ago

🏆🏆🏆🇧🇷🇧🇷🇧🇷

@yorktown7395 4 years ago

Thanks for a great video. I’m just wondering if the resistor under the main filter cap is looking a bit discolored in the middle to you?

@JC.LC. 4 years ago

It would had been nice to see measurements on this Amp....

@S.H.O.D.A.N_1 4 years ago

Thanks for this video. So few people seem to be aware of VTA products and their staggering value for money. I have my mind set on the VTA SP-14 Preamp that is noted for it's world-class sound quality. Unfortunately my speakers require more power than the ST-120 can deliver. I know that they also have a pair of higher power monoblocks, but as you stated, the sound is a little more laid back and rounded. Nothing wrong with that, though I hope to end up with some monoblocks with a more modern sound signature, with very tight bottom end, plenty of punch as well as speed. But all of the VTA products are top shelf as far as I'm concerned and anyone looking to add some of those sweet, sweet valves to their system will not be disappointed with anything they have on offer.