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Model: | ST-120 Kit: Wired & Tested |
Category: | Amplifier (Tube) |
Suggested Retail Price: | $995.00 |
Description: | Bob Latino built 60 wpc kit: wired and tested |
Manufacturer URL: | Dynaco |
Review by spike930 on January 15, 2009 at 13:47:58 IP Address: 173.114.46.145 | Add Your Review for the ST-120 Kit: Wired & Tested |
A short time ago, I purchased an ST-120 Kit from Bob Latino. It arrived in two days and was very well packed.
I've been building all kinds of kits for about 40 years(Ham radio and Audio)
and this kit rates right up there with the best of them. It's very well
planed out with illustrated instructions. Bob even included a full color
photo the chassis underside.
This kit took me about ten hours to assemble and it fired up on the first try. About another 30 mins. or so for checkout and adjustment of bias.
I was worried that this amp would not have the power to drive my RTA12Bs
enough to get a good level and range. I was using a Carver receiver before
this amp and was running much more power.
Turns out I was very much mistaken. The ST120 has tons of power.
Not only that, I now have deeper low range and the highs are not to be
believed. It wiped out my Carver. This is a very clean amp.
So if you are in the market for a fine tube amp, this one is really sweet.
You can save some bucks and build it yourself. Oh yeah, get the Cap upgrade kit too.
Product Weakness: | None that I can find. |
Product Strengths: | Very clean. Plenty of power. Sweet sounding. |
Amplifier: | ST-120 Kit |
Preamplifier (or None if Integrated): | Dynaco PAS3 |
Sources (CDP/Turntable): | Rotel CD/Dyna FM3 Modified |
Speakers: | Polk RTA12Bs about 91db |
Cables/Interconnects: | Monster |
Music Used (Genre/Selections): | Rock,Blues,Classical |
Room Size (LxWxH): | 20 x 14 x 8 |
Time Period/Length of Audition: | many hours over three days |
Type of Audition/Review: | Product Owner |
go to the HiFi section of my web page and see the series of startup videos I did on my ST120...So much fun!
Roy Bertalotto
South of Boston
Sound Artist SA200ia
Cambridge Audio 840 AZUR
VTA ST120 Dynaco Clone
Schiit Saga
Schiit Freya
Schiit Loki
Schiit Modi
Bluesound Node2i
Gustard X16
KEF LS50 Meta
Magnapan MMG
Others
Edits: 11/19/21
I expecially like the paint of the transformers.....good job....
When installing the SS rectifier, did you also go with the time-delay relay? And the diodes at the rectifier socket?
New amps may be shipping with a 2x voltage primary on the power transformer. House voltage in the US is higher than when the original DynaKits were sold.....early 60s, perhaps.
What tubes did you go with? Output? Input?
Got any shots of the WIRING end of the build? I'm really tempted by the mono blocks, the M125 for my panels.
Too much is never enough
IELOGIC Assembly book of the M125 with many function and performance mods.......
I'm going thru it right now.
Some make good sense, like increases in the values of the SCM.....
They also suggest better quality input and output hardware as well as an upgrade to the tube sockets from the Celenex.....a decent plastic...
Other stuff had occurred to me, like nylon screws to attach the driver / bias board....
Toss in a few parts value changes.
They even recommend a DELETE of the triode / pentode switch...build it ONE WAY. I'd use that space for a TIME DELAY relay board so going to a SOLID STATE Rectifier would be much easier.
Too much is never enough
[quote]When installing the SS rectifier, did you also go with the time-delay relay? And the diodes at the rectifier socket?[quote/]
Yes, I went with Time Delay and I believe I installed the diodes in the rectifier capsule itself.
Couple pictures here...I'll post more
Roy Bertalotto
South of Boston
Sound Artist SA200ia
Cambridge Audio 840 AZUR
VTA ST120 Dynaco Clone
Schiit Saga
Schiit Freya
Schiit Loki
Schiit Modi
Bluesound Node2i
Gustard X16
KEF LS50 Meta
Magnapan MMG
Others
I posted an entire pictorial of the build on my web page...Hope this helps
Roy Bertalotto
South of Boston
Sound Artist SA200ia
Cambridge Audio 840 AZUR
VTA ST120 Dynaco Clone
Schiit Saga
Schiit Freya
Schiit Loki
Schiit Modi
Bluesound Node2i
Gustard X16
KEF LS50 Meta
Magnapan MMG
Others
Very Good Documentation. Since I'm on the verge of OCD my complaint is a non-starter. I'm a stickler for color matching......
Love the 'hammered red'.....Looks like my eyes about 2 mornings a week.....How do you hold the transformers TOGETHER in the meantime? Won't they come apart some? I've never taken one apart!
VERY good lead dress and routing. Twist for noise cancelation......
I hope to apply such technique IF and WHEN I get a pair of the M125s. Which I have every reasson to believe will drive my panels to my requirements.....
Too much is never enough
No issue with the transformers coming apart. They stay together when disassembled.
Glad you liked it!
Roy Bertalotto
South of Boston
Sound Artist SA200ia
Cambridge Audio 840 AZUR
VTA ST120 Dynaco Clone
Schiit Saga
Schiit Freya
Schiit Loki
Schiit Modi
Bluesound Node2i
Gustard X16
KEF LS50 Meta
Magnapan MMG
Others
Gee, that sure looks nice. I hope you leave the doors open when you run it.
Doors open....Amp slide out....spring suspended computer fan on back of cabinet....cool is good!
Roy Bertalotto
South of Boston
Sound Artist SA200ia
Cambridge Audio 840 AZUR
VTA ST120 Dynaco Clone
Schiit Saga
Schiit Freya
Schiit Loki
Schiit Modi
Bluesound Node2i
Gustard X16
KEF LS50 Meta
Magnapan MMG
Others
I have a liking to anything Hafler, even if modded. Cheers!
That bottom picture is the Prototype cabinet for the top picture. As you can see, I had to extend the front to fit the Bias Volt meters. The bottom cabinet is available to anyone that wants it. Just pay shipping. Email me if you want it..... rvb100@comcast.net
Roy Bertalotto
South of Boston
Sound Artist SA200ia
Cambridge Audio 840 AZUR
VTA ST120 Dynaco Clone
Schiit Saga
Schiit Freya
Schiit Loki
Schiit Modi
Bluesound Node2i
Gustard X16
KEF LS50 Meta
Magnapan MMG
Others
As it turns out? A 3rd amp in the line may be where I'd land. I have low sensitivity panels.
The 2 in the 'ST' series are 35x2 and 60x2 stereo amps.....Call 'em 3 db apart.
But VTA is also doing a MONOBLOCK of 125 EACH with 4 output tubes and some Impressive looking transformers. Another 3db higher output. And it comes with all the capacitor upgrades and I think comes with a SS rectifier which is plug-in compatible with a 5AR4 type....
New amp can use up to at least the KT120 output but I think comes with 4x @6550 or maybe KT88.
One bias pot per pair of push-pull outputs. So I'd be tempted to, at upgrade or replacment to buy at least MatchedPairs.
Maybe a quad?
Chassis is nearly the same size at the stereo amps so wiring might be slightly less dense. It also has a 3-wire cord and the inputs / outputs NOW make sense with the power switch on the front and the I/O stuff on the back with a fuse holder and IEC socket. Bias check points are also on the front.
This is even further from 'Dynaco' then either of the stereo amps. this is Very Very Tempting since my panels could without question make use of the power.
Too much is never enough
Just curious.....
What output tubes did the OP go with? According to bob L, you can plug in 5 or 6 different output tubes......All the way to KT150, which IMO would kind of be wasteful......
I think it comes with 6550 but many uprate to KT88s.......
Than discussio usually turns to the CENTER driver tube......
Too much is never enough
Welcome to 'tube world'. Tube amps will always outperform solid-state of the same or similar
rated output. In fact, a tube amp will keep up with transistor amplifiers rated at many times their (tube's) rated output.
My 8 watt 300Bs kept up with a Bryston 2B until they both clipped at the same volume on identical speakers. Go figure.
I'll take issue with that. Pretty much all my listening is with tube gear (all Manley - I'm a fan) but I've had some really wonderful s/s amps over the years.
The SAE 2200's, many of which are still doing yeoman duty in studios around the world, are very good. Their P250 was one of the best amps of all time. Luscious mids, great extension at both ends, great dynamics and low-level detail - it had it all.
All the BGWs from the 70's were excellent, with great low-level detail, wonderful mids, and frightening dynamics when called on. These are widely available for generally little money. They're easy to work on, so getting one and re-capping it can give you some of the best amplification available pretty cheap.
The Yamaha B-2 was a lovable oddball, as it seemed "voiced" to sound something like a great tube amp. Liquid mids. Bottom end with just a tiny hint of whumpiness. Sadly, it was made with VFETs which are unobtainium and for which there are no substitutes. (That happens sometimes in solid-state-land.)
I heard a pair of Mac MC2500's on big B&W floorstanders set up as nearfields(!) at Kaufmann Astoria Studios and the combo was superb.
I love my Manley Snappers on the Tannoys. The Bottlehead Crack amp on Sennheiser 800's is the best sound I've ever heard. But I have also loved lots of solid-state gear that delivered the music beautifully. Tube amps will always out-perform solid-state in *some* aspects of music reproduction, and solid-state will always out-perform tubes in other ways. Pick your poison and drink it down. It's all good.
WW
"They got a handful of gimme and a mouthful of much obliged." Alberta Hunter
I think I know where the feeling of tubes having more power than a similarly rated SS amp comes from.
I've never owned tubes, but am investigating.
ONE major pointt comes to mind.
A tube amp will store energy in very high voltage (compared to SS) capacitors.
As it turns out, the drive beehind net energy storage (in Joules) is the voltage ...
A 100mfd capacitor at 400 volts is 8 Joules.
8000mfd at 50 volts is 10 joules.
So while it doesn't look like a tube amp is storing THAT much energy.....it sure IS......
I do not know what typical values are for storage but i DO know that some SS builders will 'brag' abou the PS capacitance. When they should talk about energy storage.
Too much is never enough
new VTA120 amp !!
Now available for those that need a little more power is the Dynaco VTA ST-120.
The VTA ST-120 is a 60 WATT PER CHANNEL amplifier built on the same ST-70 stainless steel chassis as the amp pictured above.
The VTA ST-120 uses three custom wound USA made transformers and is available as a KIT amp or completely WIRED and tested.
This amp, which comes with a matched quad of 6550A output tubes, has the same quality components as the VTA ST-70 listed above.
KT88 output tubes may also be used in this amp.
The power transformer instead of 360-0-360 secondaries like the ST-70 has 420-0-420 secondaries and puts about 485 volts on the plates
(pin 3) of the output tubes. The ST-70 puts about 420 volts on the plates. The stack lamination on this transformers is about 2.70 inches tall
- my ST-70's power transformer stack is about 2.05 inches high. This transformer weighs about 4 pounds more than the ST-70 transformer
and is rated at 425 milliamps of current flow.
The output transformers have 4200 ohm primaries, 40% ultralinear screen taps and are 3 7/8" tall, 3 1/4" wide and 3 1/8" deep
(about 1/2" taller, 3/8" wider and 1/4" deeper than a stock A-470 output transformer). Each output transformer weighs about
2 pounds more than a stock A-470 output transformer.
The power storage caps have a higher capacity and voltage rating than the VTA ST-70. The supplied WZ68 Weber Copper cap rectifier
has the capacity of two GZ34 tube rectifiers and has an Imax of 450 milliamps.
.
Beatnik's stuff http://web.me.com/jnr1/Site/Beatniks_Pictures.html
Photo of this ST-120 amp above from Bob's web site.
You are right - There was a ST-120 SOLID STATE Dynaco amp at one time. Bob's ST-120 amp is not really a "Dynaco" but is a custom 60 WPC amp built on a Dynaco ST-70 chassis. I have the 35 WPC version of his amp (ST-70) that I built from his kit about a year ago. Great amp kit for the money with excellent assembly instructions. It totally blows away my old my old original ST-70 for sound quality.
I put a link below to Bob's web site. There are more specifics on both amp kits that he sells. C. Wolf
I had a *real* SS Dynaco ST-120 used with a PAS-3X in the early 70s. They never produced a 6550 based stereo amp using the EL34 ST-70 chassis. That is a clever modern adaptation. Which is a completely cool idea to me!
rw
This MIGHT have been what Dynaco made IF they had seen more of a future for tubes?
A very logical extension of the ST70.......
I'm tempted.
Too much is never enough
.
Beatnik's stuff http://web.me.com/jnr1/Site/Beatniks_Pictures.html
.
Beatnik's stuff http://web.me.com/jnr1/Site/Beatniks_Pictures.html
I built one about 25 years ago. As you said, it went together without a hitch. I also built their preamp..a PAS3x, and their tuner FM3A. The amp was the easiest to put together, and a great source of pride when it worked after plugging it in for the first time.
sss
Thanks for the review. Any chance you can upload a pic?
Well that's great that someone is making some good tube amp kits. Kits are fun to build, and you often save some money. Everyone should build at least one tube amp in their life!I wonder where he is getting those ST70 chassis from? Did he buy up the last of some stock somewhere, or is he having these made? Not that it really matters, but I am just curious.
Obviously he is having the transformers wound for these amps, I don't think they could possibly be stock items at any distributor on the planet. Unless maybe he has a time machine.... :-)
I've had a number of tube amps, most I sold. I got a nice Citation II with McShayne mods for about $950 a few years back, and I'm keeping that one.
I also have an AMC CVT-2030 this is a class-A, hybrid MOSFET/EL-34 amp, you can sometimes pick these up for $200. Very under-appreciated amp. It's a very good sounding amp. True, it's only ~35 watts a channel, so it has it's limits. But for the $200 I've seen them sell for on eBay it's a STEAL. Designed by a guy who designed amps for NAD, built by Welltronics, who builds stuff for lots of other companies. Really hard to beat EL-34's for $200!
Edits: 08/16/12
New chassis is heavier gauge AND is stainless steel.
Weighs more, too, and will not 'rust'...... A lifetime part.....
As near as I can tell? main difference between the VTA amp and the Dynaco? Driver board uses different tube and has a single bias pot for EACH output tube. Tube compliment for the new board? a SINGLE tube shared and a 'longtailed pair', whatever THAT is. One for each side. Some kind of constant current source here, in the form of a solid state device. The 12AU7 tubes have a few replacements but the MAIN benefit (like 80%) can bbe had with the SINGLE CentER TUBE being swapped for something else? Maybe a 12BH7.....but others work as well.
Original tubes from Dynaco? I think a 7119 gets awful press. You can also get a 6SN7 or some such whivh in the new board configuration which has quite a number of fans, too.....
You can replace the recitifer tube with a SS device AND add a time delay board to allow the heaters to come UP before the HV comes on.....good for tube life.
You can also add an auto bias board, but that's part of the FUN.
Too much is never enough
New chassis is 18ga STAINLESS......
not the 16ga plated steel of the original......
Too much is never enough
nt
Dmitri Shostakovich
I know the new is heavier.......but got the #'s swapped.
Stainless is also, in this case NON magnetic...but you can induce a current into the stanless and still end up with a magnetic field.
6 different kinds of magnetism....Is this Paramagnetic or other?
Has anyone credible said anything BAD about this amp?
Too much is never enough
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