Dynaco Stereo 120

Hey  rixthetrick.

I am the builder of that particular amplifier. I do a lot of these, each one being slightly unique to itself. I currently have 2 units to start on after they clean up and then pass transformer tests. These sound ridiculously good, I do a lot to them, for that reason. I'm also a bit OCD and a "car guy" so looks are very important to me also. 

These sell for $599.95 plus shipping.

I'll share a correspondance I received yesterday from the buyer of one of these. He's had it for less than a week now:   

" A battle is ensuing with all my audio buddies because I basically slammed them for initially being dubious and skeptical of my getting the 120. I’ve tested tons of amps and you are 100% correct. This thing is a giant killer. It’s the best thing I’ve ever heard and I’m dead serious." 

He also owns 2 of my PAS tube preamps. You can see those on the facebook too.

Here's his comment on the PAS-M he recently purchased: " I can’t tell you how amazed I am. This preamp will get 1st prize in my review for sure. When you get a chance play a piece on YouTube by Bill Evans called “Danny Boy” at 1 minute into song for the remaining two minutes you will hear these little symbols shimmering like sparkles in the right channel. With the new preamp you made, this shimmer Comes through more clearly more defined more vibrantly than any other preamp I’ve ever heard. I was rolling hysterically  last night. You are the man!"

Here's a link to my facebook where you can find photos and other information on some of the past 120's and some other Dynaco/Dynakit gear I've done recently. -Kenny

Kenny - I was looking around your Facebook pages, that red ST120.. Man that is a thing of beauty. I wire up RTU panels for my PLC and SCADA for oilfield tank batteries and I am fussy about what I put out also.
Your wiring is top notch, absolutely clean and neat (I said that oldhvymec) and it sure is.

So in the review, it stated Dynaco weren’t moving over to SS until it came up with a product at least as good as their valve amps. You know this device as good as anyone I suspect, did they get it right?

Absolutely, when outfitted with quality caps and resistors these are quite impressive. Of course adding the new and increased capacitance helps tremendously and the regulated power supply is a must. The thing just performs to the amazement of all who listen. It will make a believer out of most any skeptic. Use of solid state or tube preamp seems not to bother it at all. I just got my website up going today so you might check that out too. https://funtasticvintronics.com/
I'm trying really hard to get away from ebay, they have just ruined a wonderful thing.

I have to say, I have gone through a great deal comparing many amps, integrated amps and preamp combos over the course of the past two years. I just put a few pics on a flickr to begin with. I have many more to add and I will.

https://www.flickr.com/photos/190302627@N04/

These are just some of the pictures. I have a group of guys I listen with at various places and we share each-others equipment. In my rooms and others, I have compared lots of things. 

Parasound Halo A23
McIntosh MHA100
Yamaha AS1200
Yamaha S501
Primaluna EVO400
Dynaco VTA ST70 Bob Latino with KT88's
NAD 326BEE 
Decware SE84UFO
Dynaco PAS II Funtastic-Vintronics
Dynaco PAS NG Funtastic-Vintronics
Aretha Erhard Audio
Glow Amp One
Qunpu A6000
Schiit Freya Plus

Speakers:

Caintuck Audio LII Fast 8 Betsy's
Klipsch Heresy II
Magnepan .7
Dynaco A10

What I've learned is that you have to match the amps to the proper speakers to get the best synergy. In the end though, what I've noticed is that I have generally found that I prefer the spatial separation that tubes typically offer over solid state, particularly with regard to the Yamaha's. IMO, they sound somewhat sterile and 2 dimensional. Some prefer that type of sound. Out of this group, Kenny Russell's rebuild on the Stereo 120 solid state transistor had the most profound impact on me both in sound and emotionally. Whenever I read lots of negative chatter about the 120 in forums, I remove myself, because in my own profession, I know what forums do to people. They just parrott the same things others say without even listening to the component in question.  

So far, for me and this is just my own personal opinion. This Stereo 120 NG Kenny Russell built for me is the only solid state amp I've ever heard that offers the same spatial separation I've gotten from tubes but I'm still perplexed as to why. I just know what I'm hearing. For example, I can run my Dynaco ST70 NG with my .7's Maggie's but once I start to play them at louder levels, they tend to clip just a bit so I back them down to normal listening levels where they sound wonderful. I didn't have that issue at all with the Primaluna EVO400 because it has about double the power output. 

So I decided on Kenny's 120. When I first listened to it, I literally dropped my jaw in disbelief AT ANY PRICE $. This is impossible! I can't wait till my friends come over to hear this amplifier coupled with another masterpiece of Kenny's, a PAS NG. This is my favorite setup with all my speakers. The 120 sounds absolutely beautiful and I like it more than anything I've heard thus far. It drives the Maggie's to perfection with ultra tight bass and crystal clarity. I have much more to share and explain, but for those who think these 120's are a relic of the past, shame on you. 

If this amp has a circuit the same as the original ST-120, one of the reasons it can sound as nice as it can is that it makes a fair amount of 2nd ordered harmonic. This, and the 3rd, if in sufficient amount, can mask the higher orders to a certain degree and result in a fairly smooth sounding amp unless you push it hard. Modern electrolytics seem to be a bit better than the ones used back in the 1960s and early 1970s; I'm sure that doesn't hurt either.

For my bedroom system I use an amplifier made by Radio Shack (SA-175C) that is very similar- the same circuit sans power transistors. It makes about 5 watts, but I never push it past one. At lower power levels its very smooth (and of course I've serviced it out) but it does get less polite at higher levels.


The key to working with amps like these is to make sure that the speaker is easy to drive and not low impedance. The low impedances should be avoided as they interact directly with the output coupling cap and can introduce low frequency phase shift which messes with bass impact. The ST120, being an early solid state design, is not very forgiving if you do something dumb like short out the speaker terminals, do anything adverse to its ability to cool itself or try to play it on a difficult load and get it really hot! But if you go easy on them they hold up quite well. 


I've repaired many of the ST120s over the years- fixing consumer electronics is how I put myself through school. The amps seen at the website are a bit of eye candy- its nice to see someone really taking the time to do a neat job! IMO the insides are where the money that you spend on audio equipment should go. Its nice to see someone really taking pride in their work.