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Latino "tubes 4 hifi" Dynaco Stereo 70 replica review

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Posted on April 13, 2011 at 07:52:36
TXinD76121
Audiophile

Posts: 2
Location: Wisconsin
Joined: April 13, 2011



After two years with my ST70 amp I thought it might be time for a review. I bought an ST70 from Bob Latino in Massachusetts in April of 2009 and have used it virtually every day ever since. I work at home so I put a lot of hours on the stereo. I also have a Bryston 2B SST^2 which is a $3k 100-wpc solid state amp, or as Bob calls them, a "sand amp."

Description: this is properly a "replica" Dynaco Stereo 70. (Link below.) It's made from all-new parts and doesn't contain any parts from a vintage unit. The input board is the VCA70 PCB which is also available as a mod/replacement/upgrade for vintage units.

I had Bob build mine. It's also available as a kit if you want to build it yourself. Even hand built, it's remarkably cheap--I believe mine cost a little over $1k "loaded" with all the (c. 2009) options.

I've had my amp configured with KT-66's (shown in the pic) and EL-34's. They both sound great but a little different--the KT-66's are a little more liquid and detailed but a little thinner-sounding. I prefer EL-34's. It would depend on your speakers (and tastes) I suspect. I have several sets of EL-34s and I wish I could remember where I got the set I'm using now--I bought them from Ebay but I can't recall from whom.

The critical tube is the center input (small) tube. Some options are just noisy and hissy and don't work. The Mullard CV4024 is the one to use.

If the amp has any fault it's that it's a little hard on the (tube) rectifier, and goes through them fairly quickly. I bought an expensive NOS Mullard which is supposed to be bulletproof, and so far has been. Bob recommends JJ GZ34s and those work well. I think they even sound a touch better than the old Mullard, but I wouldn't swear to that. In two years, one JJ and two Mesa rectifiers in my amp have gone the way of all things.

Don't care about that, though. If you don't like the idea of caring for and feeding a tube amp, you should probably go with something designed to be easy to use like the Prima Lunas.

I suspect you need tube-friendly speakers for this amp, and there aren't many of those around any more. In England, Peter Comeau designed an upgraded replica Dynaco A-25 and a floorstanding version of same which was marketed as a kit or in various states of assembly by _Hi-Fi World_ magazine's "World Designs" subsidiary, but Peter (former chief designer of Mission speakers, among others, if you don't know the name) got a job overseeing a speaker factory in China (or something like that) and off he went. The World Designs tube amps have been resuscitated by another party, but not the speakers, as far as I know. Icon Audio in England also makes a deliberately tube-friendly speaker called the MFV 3. I'd try a pair but they want $561 shipping to Wisconsin which is a tad excessive. I have some old Tannoys which I keep trying to get rid of but can't, and they are also a good match for a 35-wpc push-pull tube amp. I've heard that Vienna Acoustics Mozarts are also a good match. I'm sure there are others, but those are the ones I know. I wish one of the snooty stereo magazines would write an article on tube-friendly speakers (other than horns for flea-powered SET amps, I mean) but I guess that would be entirely too practical for them. They don't seem too interested in speakers that cost less than the price of a luxury car anyway. But I digress.

Bottom line: I totally love this amp. It's one of the best hi-fi purchases I've made in my life, and that's saying something because I've been an unregenerate over-purchaser of audio equipment over the years. It's far from the most expensive amp I've owned--or own now--but it's the one that has given me the most pleasure. My 3X-as-expensive Bryston is a bit punchier and more articulate in the bass, but the ST-70 betters the Bryston in every other parameter I can think of. And I actually prefer the bass of the ST-70 with my Tannoys--it's not as hi-fi, but it sounds more like the real thing to me. (I listen mostly to ensemble jazz.)

It does take a bit of patience to deal with tube-rolling and biasing (I bias the amp about every other month--you need a multimeter (I got mine from Radio shack) and a small screwdriver), but to me it's well worth the trouble. I just love the sound--liquid, dimensional, rich, musical.

I should probably add that this doesn't sound very much like an original Dynaco ST-70, which I recall as being easy on the ears but woolly and soft and somewhat slow. The current version just sounds like any really good modern tube amp, not like a gloss on the old vintage amp. The speed and transients are in a different category at least. It's been a long time since I've heard an old Dynaco ST-70, though.

Given the price, this is a great bargain, especially if you are competent to put it together yourself. Even if you're not, though, it's still a great amp for the money.

I've built my system around this amp and will continue to do so as long as I'm able to.

Bob (who I've never met) is good to deal with and responds to questions promptly. He makes two other amps, the ST-120 (KT-88s, 60 wpc) and the new M-125 monoblocks, which can be configured for 65 wpc with 2 KT-88's each, or 120 wpc with 4 KT-88's each.

Oh, by the way: if you get this amp, get the capacitor upgrade but don't bother with the Triode switches (unless those aren't an option any more)--my amp has them but I much prefer the sound in push-pull (pentode) mode. If you have ONLY a CD player, I see you can now get the amp with a volume control on it so you can run your system without a preamp. Mine doesn't have that.

Negatives? It looks like a Dynaco. I like that about it, but your wife might not. :-)

Hope this has been of use or interest to someone out there. Keep it fun!

 

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    ...
I highly agree..........., posted on April 13, 2011 at 09:29:15
rgurney
Audiophile

Posts: 343
Location: Virginia
Joined: May 1, 2001
I have both the Latino VTA ST-70 and the VTA ST-120, both built from kits. These are the best electronic kits I've ever built. Both amps have the Russian PIO cap upgrade. The ST-120 can run both the KT88 and KT120 for output tubes.

 

RE: Latino "tubes 4 hifi" Dynaco Stereo 70 replica review, posted on April 13, 2011 at 10:33:03
Palustris
Audiophile

Posts: 2460
Location: Cape Cod
Joined: September 12, 2008
I have to agree that these ST70 replicas from Latino and Triode are easily the best value tube amps for the money. As an added enticement, since these are domestic products, there is no question of build quality or ease of maintenance or repair. Every day there is a request for a schematic for some Chinese tube amp on the various forums and if a schematic is found it rarely matches the product.

As to the rectifier tube, there is no way a current production 5AR4 can hold up under the large power supply capacitors used in these modern amps. The solution is easy: use 5AU4 or 5V3 rectifiers. While you can NOT use these in an original ST70, the new power transformer can easily handle the heater current. According to the tubes4hifi web site, "The two tube heater legs are rated for 5 amps each instead of 3 amps each." The 5AU4 and 5V3 require almost 4 amps so will be perfect in these amps. Until these rectifiers are better known they are still about $10 on epay. Be patient and pick them up when they appear and don't bid silly prices on them. I have a big stash all bought for $5 - $10 a tube.

 

RE: Just Got My Kit Yesterday, posted on April 13, 2011 at 10:42:16
thegage
Audiophile

Posts: 1163
Location: Western Mass.
Joined: April 29, 2000
And can't wait to start building.

As I understand it, it is pretty much a new design made to look like an old Dynaco (even down to the Stereo/Mono switch on the front panel, which in this amp is non-functional and is for looks only), which does cause a lot of confusion.

John K.

 

RE: I highly agree..........., posted on April 14, 2011 at 08:49:45
Mick Wolfe
Audiophile

Posts: 3513
Location: AZ
Joined: October 10, 1999
Contributor
  Since:
September 4, 2000
I have both versions as well. Terrific values that still seem to be flying under the radar. The ST 70 is a sub $1000 miracle.

 

RE: Latino "tubes 4 hifi" Dynaco Stereo 70 replica review, posted on April 14, 2011 at 09:06:33
Michael Samra
Dealer

Posts: 36118
Location: saginaw michigan
Joined: January 30, 2005
One more thing to mention.This amp is 100% american made other than a few resistors and maybe the Russian pio caps if you got those.Thats important and not only that,these amps are head and shoulders above the original design and I have seen this amp run circles around amps in the 4 to 6k dollar range.
"For every complex problem there is an answer that is clear, simple, and wrong" H. L. Mencken

 

Not The Only One, posted on April 14, 2011 at 09:37:32
Diode
Audiophile

Posts: 511
Location: SE Wis
Joined: September 11, 2005
""I have to agree that these ST70 replicas from Latino and Triode are easily the best value tube amps for the money.""

I haven't heard the ST replicas and I'm sure they sound great, but I have owned Quicksilver products, and I and others can tell you that Quicksilver amps are also some of the best value tube amps available for the money.

 

Wrong, wrong, wrong, posted on April 14, 2011 at 10:04:58
Where's the slick website showing the designer in a thoughtful pose? Moodily-lit product? The great ad copy about capturing the essence of music or some similarly lofty goal? And what's with the price? Under a thousand bucks for the entire kit? How's about charging that much for just the coupling capacitors, and making the buyers feel lucky to get them at all! Everything about those amps just seems too freaking...reasonable. Your high-end credibility is in danger, so you'd better append your review with a comment to the effect that "Best results can only be had with the appropriate speaker, power and interconnect cables, cryo-treated NOS tubes, footers, power outlets, wall plates and isolation bases" preferably costing far more than the amp itself. And then, only for casual listening!


;-)

 

RE: Latino "tubes 4 hifi" Dynaco Stereo 70 replica review, posted on April 14, 2011 at 12:19:55
TXinD76121
Audiophile

Posts: 2
Location: Wisconsin
Joined: April 13, 2011
Palustris,
Thanks for the suggestion. I checked with Bob, and he says he's never tried either the 5AU4 or the 5V3 as a rectifier in his amp; the only alternative he recommends is the 5U4. He thinks the 5AU4 or 5V3 might lower the power of the amp, even if only slightly, and says that the amp would need to be rebiased when using those tubes. I don't personally know anything about electronics, so I'm reluctant to try something Bob doesn't recommend, but maybe that's just me.

 

RE: Not The Only One, posted on April 14, 2011 at 12:25:20
Palustris
Audiophile

Posts: 2460
Location: Cape Cod
Joined: September 12, 2008
I had a pair of the original Quicksilver KT88s over 20 years ago so I do agree they are a good value and sound good. The Quicksilvers have their own problems with rectifiers and their ownership has left me with a lifetime supply of 5AR4s. My 5AR4s only go into older amps that have a rectifier winding rated at 2 or 3 amps; all new builds get the 5AU4 or 5V3.

 

5 volt rectifiers in the VTA ST-70, posted on April 14, 2011 at 13:31:16
Bob Latino
Audiophile

Posts: 209
Location: New England
Joined: May 21, 2007

Above is chart of 5 volt rectifiers. Probably any one of them "could" be used in the VTA ST-70 because the VTA ST-70 has a 5 volt 4 amp rectifier line.

A GZ34 rectifier is recommended for use in the VTA ST-70 because the filament is indirectly heated and the warm up is slow. A GZ34 also has a lower voltage drop than most other rectifiers. This keeps the B+ voltage high and allows the amp to make more power. A 5AU4 and 5V3 have higher current draws but also a higher voltage drop. With a 5AR4 in the VTA ST-70 the B+ voltage is around 435 to 440 volts.

The use of a 5AU4 or a 5V4 rectifier will drop the B+ to about 400 volts. This will cause a slight drop in the power of the amp. Whether the power loss will be noticeable or not, I can't say.

I have used a 5U4 and a Weber WZ68 solid state rectifier in place of the GZ34 tube rectifier in the VTA ST-70 and both work fine. I have never used a 5AU4 or a 5V3 simply because I don't have either one of these rectifiers here. Both should work OK in these amps also ...

Bob Latino

 

RE: Latino "tubes 4 hifi" Dynaco Stereo 70 replica review, posted on April 14, 2011 at 15:07:19
Michael Samra
Dealer

Posts: 36118
Location: saginaw michigan
Joined: January 30, 2005
The 5au4 or 5V3 will work in Bob's amps because he uses much heavier duty transformers than the originals.If you ever have any doubt whether or not filament stress is too much for an amp with a particular tube,just measure the filament voltage and if its 5v volts,you are good to go as in the case with the 5AU4.
"For every complex problem there is an answer that is clear, simple, and wrong" H. L. Mencken

 

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