The Stereo 70 was a decent amp, though not exceptional, but IMO the cost to operate one today is more than I'm willing to put up with, as with most tube equipment. Good tubes are expensive and the output tubes need to be replaced every now and then. There are all manner of mods available to improve it- that should tell you something right there.
The Stereo 120 is widely considered to be one of the worst solid state amps ever produced, both sound-wise and for reliability. One should probably have one for that reason alone.
New kits will likely have improvements and I can't comment on those, having no experience with them.
Don't get me wrong as I've owned a lot of Dynaco equipment and enjoyed most of it. It's just that we've come a long ways since then and can do much better, especially DIY.
The Stereo 120 is widely considered to be one of the worst solid state amps ever produced, both sound-wise and for reliability. One should probably have one for that reason alone.
New kits will likely have improvements and I can't comment on those, having no experience with them.
Don't get me wrong as I've owned a lot of Dynaco equipment and enjoyed most of it. It's just that we've come a long ways since then and can do much better, especially DIY.
The st-120 on Tubes4hifi.com has an unfortunate name, the version on his site is a st-70 heavily modified to run kt-88 output tubes. His kits have upgraded power transformers and much better driver circuits. That eliminates 2 of the st-70's major problems. The only issue left is the chassis size/layout.
I have looked at the ST-70 and the ST-120 on that website and they look nice. I have read that the ST-70 and it has been called the poorman's McIntosh and with 350,000 made, it says something about the amp itself. With regards to the new ST-70 amps being made, a lot of the problems that were known with the older original Dynacos have been addressed. I have emailed Bob Latino and for his kits it seems that they are straightforward and easily done by even a novice such as myself. There probably are worse and better PP amplifiers out there, but at this price and to have everything minus the solder, soldering iron, and time it is hard to beat.
If you want for a broader opinion to what it has been compared to, then look at a website that has been in a few posts on diyaudio.com
The Ten Most Significant Amplifiers of All Time | AVguide
And at 9 pages, it makes for an interesting read to as what staffers there think is the best of all time. Probably all subjective, however it gave me something to think about.
If it is DIY kits that you are looking at, take a look at oddwatt offerings from oddwattaudio.com or the Elekit 6550 SE amp from vkmusic.com
(I'm probably going with a ST-70 a lot later on after i am done my first three projects, so there might be some bias)
If you want for a broader opinion to what it has been compared to, then look at a website that has been in a few posts on diyaudio.com
The Ten Most Significant Amplifiers of All Time | AVguide
And at 9 pages, it makes for an interesting read to as what staffers there think is the best of all time. Probably all subjective, however it gave me something to think about.
If it is DIY kits that you are looking at, take a look at oddwatt offerings from oddwattaudio.com or the Elekit 6550 SE amp from vkmusic.com
(I'm probably going with a ST-70 a lot later on after i am done my first three projects, so there might be some bias)
The main positive quality of the *original* ST-70 and the lower power SCA-35 were the output transformers. Being smaller and lower in power, due to certain realities of winding output iron they happen to have a good bandwidth.
ALL of these early tube amp designs used a fair amount of global loop feedback - mostly to maintain the specification that was more or less *required* in that day of "20cycles to 20,000cycles +/- 1dB". Remove the feedback and most of the output iron would not permit a flat response to 20kHz. The effect of this is/was to make squarewaves, especially if there is any reactance to the load (and there is...) have a fair amount of ringing. The more feedback and the less the bandwidth of the output iron, the more ringing is introduced.
The input stage of the original ST-70 did some things with the input stage to in effect add some "EQ" so that the effect of the feedback would be less severe...
So my point is that modern variants of these amps, using different input stages could well sound better, a lot depends on things that one can't really know without seeing specs, schematics and actual real world tests of the amp.
It's impossible to know what these different companies have done or engineered for these new output transformers. It is certainly possible to improve on the old Dyna iron, but then it's not Dyna iron! Copying Dyna iron depends on proper reverse engineering of the old one, and then proper reproduction...
Anyhow, kits are nice, fun and can always be modified by the owner at a later time and date! And, you will know what is inside.
_-_-bear
ALL of these early tube amp designs used a fair amount of global loop feedback - mostly to maintain the specification that was more or less *required* in that day of "20cycles to 20,000cycles +/- 1dB". Remove the feedback and most of the output iron would not permit a flat response to 20kHz. The effect of this is/was to make squarewaves, especially if there is any reactance to the load (and there is...) have a fair amount of ringing. The more feedback and the less the bandwidth of the output iron, the more ringing is introduced.
The input stage of the original ST-70 did some things with the input stage to in effect add some "EQ" so that the effect of the feedback would be less severe...
So my point is that modern variants of these amps, using different input stages could well sound better, a lot depends on things that one can't really know without seeing specs, schematics and actual real world tests of the amp.
It's impossible to know what these different companies have done or engineered for these new output transformers. It is certainly possible to improve on the old Dyna iron, but then it's not Dyna iron! Copying Dyna iron depends on proper reverse engineering of the old one, and then proper reproduction...
Anyhow, kits are nice, fun and can always be modified by the owner at a later time and date! And, you will know what is inside.
_-_-bear
Fwiw I was looking at the VTA kits from tubes4hifi. Not an original. I like having the higher power output than they smaller ones. But if it as the expense of significant interference and distortion it is not worth it. Does anyone know offhand of any thuroigh reviews of the various kits. I have been searching and they are tough to come by.
From what I have heard, it is a relatively good PP amp for the price (I have looked at a small number of reviews on-line search "Bob Latino ST-70 review" and wade throught the ones that are not connected to the site itself).
There are worse out there for the price and most of them are Chinese built amps with questionable schematics (they don't follow the schematic) and/or parts (not the best quality).
I'll go through the steps I went through on figuring on what to build (as an all in one kit) and or start a project on (you source the parts and change as you see fit).
You have to decide on what you want to do. A vacuum tube amplifier? Headphone amplifier? Solid state/chip-amp amplifier? Do you want a kit to build from? Or do you want to hunt down the parts that you don't already have in your stash or workshop. Do you want a PP or SE tube amplifier?
I am not sure from the original post that this is what you want. Give those answers to the forum members or ask the right narrow question and you will get a lot of people chiming in and from there you can make a more informed decision.
The great thing about a kit is that all you have leftover is a bunch of empty bags and this might be your thing. I like to hunt the parts down and follow a schematic and then say, I built it myself and upgraded that and thought that this was overkill so I used something cheaper and so on.
I have one of the st-70 amps, original iron, New driver.
I'm using it with an aikido pre and stacked quads. I would recommend it in a heartbeat, but using kt66 instead of el34s. The kt66 are just a little more detailed and cleaner....... But of course ymmv.
Btw his kit is pretty good value when you add up the cost of buying and refurbishing an old one (plus I think the new power tx is a higher spec).
Also, I think the chassis is very neat - a big advantage imho.
Fran
I'm using it with an aikido pre and stacked quads. I would recommend it in a heartbeat, but using kt66 instead of el34s. The kt66 are just a little more detailed and cleaner....... But of course ymmv.
Btw his kit is pretty good value when you add up the cost of buying and refurbishing an old one (plus I think the new power tx is a higher spec).
Also, I think the chassis is very neat - a big advantage imho.
Fran
I wish you would edit your title to rename your St-120 a Latino ST-120. Actually the title doesn't say it all, it is totally misleading. I own an original Dynakit ST120 with djoffe based bias & my own heat loss upgrades and run it 17 hours a day. Transistors use a lot less power than tubes at low watts. Also the dynakit St120 sounds better than the dynakit ST70 I have even though the ST70 has new electrolytic capacitors, metal film resistors,paper capacitors replaced with plastic,new output tubes and a good rectifier tube. The ST70, by contrast, doesn't have to be turned off during lightning storms like we had last night.
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Not trying to start an argument here, but with that logic your "original" dynakit is not a dynakit at all but a indianajo dynakit. ;-)
My point is this, I don't know much about this hobby at all. I am wanting to learn, and to get a good start. I was looking at those kits, it said st-70, st-120, so thats what i conveyed here. I saw other kits that were similarly named, and just assumed they where all varients but similar at heart.
Now to what I am wanting to do,
I have a pretty nice home theater setup using modern store purchased components. Marantz sr7001 as a preamp / NAD T955 Amp etc. etc. etc. None of it is 30k McIntosh, but its good midlevel stuff.
I have an extra set of Klipsch SF-1 floor speakers that are sensitive at 94db @ 1m. And also another set of boston acoustics just sitting around that I would like to do something with.
Which takes me to the point here, in my bedroom I have a crappy little ihome dock or something that I listen to music while tooling around my room. I would like to build a kit stereo tube amp, that looks atractive to put in my bedroom, with probably those klipsch speakers. I want for this to have a nice sound. It does not have to beat out my main listening room, but good enough that I can listen to it while reading at night, etc. And I want it to look very very nice as a focal point in my room.
I really don't want have to use a pre/amp simply because I don't want to sacrafice tons of counter space. Which is what i like about those bob latinos. You can use them with / without a pre. Further, I think they are pretty. But that is literally all that I know about them. Which is why I asked your opinions of them...
My point is this, I don't know much about this hobby at all. I am wanting to learn, and to get a good start. I was looking at those kits, it said st-70, st-120, so thats what i conveyed here. I saw other kits that were similarly named, and just assumed they where all varients but similar at heart.
Now to what I am wanting to do,
I have a pretty nice home theater setup using modern store purchased components. Marantz sr7001 as a preamp / NAD T955 Amp etc. etc. etc. None of it is 30k McIntosh, but its good midlevel stuff.
I have an extra set of Klipsch SF-1 floor speakers that are sensitive at 94db @ 1m. And also another set of boston acoustics just sitting around that I would like to do something with.
Which takes me to the point here, in my bedroom I have a crappy little ihome dock or something that I listen to music while tooling around my room. I would like to build a kit stereo tube amp, that looks atractive to put in my bedroom, with probably those klipsch speakers. I want for this to have a nice sound. It does not have to beat out my main listening room, but good enough that I can listen to it while reading at night, etc. And I want it to look very very nice as a focal point in my room.
I really don't want have to use a pre/amp simply because I don't want to sacrafice tons of counter space. Which is what i like about those bob latinos. You can use them with / without a pre. Further, I think they are pretty. But that is literally all that I know about them. Which is why I asked your opinions of them...
It would seem to me that a Stereo 70 would be kind of big, and kind of powerful for a pair of wild and crazy Klipsch speakers in a bedroom (unless you have a very large bedroom, I suppose). A Dyna ST-35 (the little brother to the ST-70, with EL84/6BQ5 outputs) would be the better choice IMHO. It was a better sounding amp, too. Is there a Dyna ST-35 revival kit available? If not, there oughtta be...
Edited to add:
They do make it -- ST-35 KIT (120 VAC)
Edited to add:
They do make it -- ST-35 KIT (120 VAC)
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If you can get by with 17W/CH which I think your 94 dB spkrs can handle nicely, the ST-35 might be worth a look as EL84 tubes sound great. No argument with most people there!
You can add a volume control too. The EFB mod is well worth implementing.
There is the exact clone from dynakit.com and kits from Triode Electronics which offer a similar circuit with more driver tube options.
There is a new board coming out with the EFB mod. Check out diytube.com. Triode's kit uses diytube.com's board.
Another good option is to find a working Dynaco amp and restore. Lot's of different board options for the ST-70 and SCA-35 can be turned into a ST-35 with volume control using ST-35 type boards for improved performance. ST-35's are rare, but SCA-35 's can be picked up for reasonable prices as many were built. Both 35's use the same OPT (output) transformers and PS (powersupply) transformers. The SCA is integrated, but as you will read, not the best pre-phono circuit and uses the hard to get so expensive 7199 driver tubes.
The ST-35 has been said to be the best sounding stock Dynaco amp.
Randy
You can add a volume control too. The EFB mod is well worth implementing.
There is the exact clone from dynakit.com and kits from Triode Electronics which offer a similar circuit with more driver tube options.
There is a new board coming out with the EFB mod. Check out diytube.com. Triode's kit uses diytube.com's board.
Another good option is to find a working Dynaco amp and restore. Lot's of different board options for the ST-70 and SCA-35 can be turned into a ST-35 with volume control using ST-35 type boards for improved performance. ST-35's are rare, but SCA-35 's can be picked up for reasonable prices as many were built. Both 35's use the same OPT (output) transformers and PS (powersupply) transformers. The SCA is integrated, but as you will read, not the best pre-phono circuit and uses the hard to get so expensive 7199 driver tubes.
The ST-35 has been said to be the best sounding stock Dynaco amp.
Randy
I was reading about Bob Latino's offerings. It wasn't apparent to me that the ST-120 you were writing about is a gussied up ST-70 with the higher capacity power transformer, a driver board with three 12AX7's, and KT88's instead of EL34's. All I can think of is that the original ST-70 ran really hot as it was. KT-88's on that chassis would be awfully close together, and would probably run quite hot. I don't know about the long term reliability of that scheme, but they do say they use a heavier gauge stainless chassis that acts as a better heatsink. OK, I guess so...
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ElCid,
Buy the kit.
The ST-70 is NOT too much power for the Klipsh.
Run the outputs in triode, not pentode - I think you will prefer the overall sound.
Use the smallest value resistor on the cathodes (not sure what they use, but if it is the stock value from the original use a value 1/10th) and set the bias with a DVM. You will like the change in sound.
It's true that the smaller Dyna sounds good, but imo it's too low in power even for your speakers...
I'd not use the KT-88 version myself, but it may not make any difference. There are no
real KT-88s around, these are new tubes called "KT-88". Which were originally just Euro/British 6550s...
One thing to be aware of is that imo the larger xfmr used in the MkII and MkIII did not sound good at all... so if they copied those for the higher power version, I personally would advise steering clear.
Go for it. Enjoy the kit building. Stop worrying. You can always sell it and get most or all of ur money back later if you want to. After all it will be an assembled kit when ur done.
_-_-bear
Buy the kit.
The ST-70 is NOT too much power for the Klipsh.
Run the outputs in triode, not pentode - I think you will prefer the overall sound.
Use the smallest value resistor on the cathodes (not sure what they use, but if it is the stock value from the original use a value 1/10th) and set the bias with a DVM. You will like the change in sound.
It's true that the smaller Dyna sounds good, but imo it's too low in power even for your speakers...
I'd not use the KT-88 version myself, but it may not make any difference. There are no
real KT-88s around, these are new tubes called "KT-88". Which were originally just Euro/British 6550s...
One thing to be aware of is that imo the larger xfmr used in the MkII and MkIII did not sound good at all... so if they copied those for the higher power version, I personally would advise steering clear.
Go for it. Enjoy the kit building. Stop worrying. You can always sell it and get most or all of ur money back later if you want to. After all it will be an assembled kit when ur done.
_-_-bear
If your talking about Bob Latino's ST-70 kit I've read the low gain version ( 12AU7 tubes) sounds better especially with the mentioned optional tubes to swap in such as the 12BH7A Yes extra power won't hurt! I think KT-66 would be a great choice for output tubes over EL34's too.
I think a volume control could be added to the low gain version but a line stage preamp may be preferable.
IF you have separate connections for the woofer and tweeter you could also use a ST-35 per channel. Better for stereo separation than to use one amp for the woofers and the other for the tweeters. Those ST-35's are very compact.
Randy
I think a volume control could be added to the low gain version but a line stage preamp may be preferable.
IF you have separate connections for the woofer and tweeter you could also use a ST-35 per channel. Better for stereo separation than to use one amp for the woofers and the other for the tweeters. Those ST-35's are very compact.
Randy
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