I have a Tubes-4-HiFi ST120. I picked up the kit a couple of years ago from Bob Latino. I have a small set of amps, the ST120 from Bob, a pair of Dynaco MK3's with the Triode Electronics Driver boards, a pair of Grommes 260A clones that I built. Each sounds a bit different. The most enjoyable to listen to is the Grommes 260A for some reason, just pleasant and with good power.
Next would be the ST120 which has a lot of power and is a very crisp sounding amp. I have it built with the higher gain input stage and would likely go for the lower gain option if I had thought about it. Quality of the parts are good and you can upgrade a few things like caps, and power supply filter size as well as a triode / pentode switch. The chassis is nice thick stainless and looks very nice. The kit is straight forward to assemble and came with just about everything needed except for a hot iron. It's a nice compact amp, with a good amount of features and options and lets not forget a good dose of power. I'm running JJ's and KT88 with a weber copper cap in mine.
The rebuilt MK3 sounds good but my limited listening and that I really like the 260A's put it in at a close 3rd, need more time to evaluate. These are with JJ KT88's and GZ34, with ECC802's.
The Grommes Amp uses Edcor transformers, the ST120 uses Bob's custom transformers and the MK3's used orig Dynaco iron.
I don't really think you can go wrong with the Tubes-4-HiFi ST120 it's a fun build and something you will be proud of when done.
http://dynacotubeaudio.forumotion.com/
Sandy
Next would be the ST120 which has a lot of power and is a very crisp sounding amp. I have it built with the higher gain input stage and would likely go for the lower gain option if I had thought about it. Quality of the parts are good and you can upgrade a few things like caps, and power supply filter size as well as a triode / pentode switch. The chassis is nice thick stainless and looks very nice. The kit is straight forward to assemble and came with just about everything needed except for a hot iron. It's a nice compact amp, with a good amount of features and options and lets not forget a good dose of power. I'm running JJ's and KT88 with a weber copper cap in mine.
The rebuilt MK3 sounds good but my limited listening and that I really like the 260A's put it in at a close 3rd, need more time to evaluate. These are with JJ KT88's and GZ34, with ECC802's.
The Grommes Amp uses Edcor transformers, the ST120 uses Bob's custom transformers and the MK3's used orig Dynaco iron.
I don't really think you can go wrong with the Tubes-4-HiFi ST120 it's a fun build and something you will be proud of when done.
http://dynacotubeaudio.forumotion.com/
Sandy
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Lets keep poorly designed Chinese amps off and keep any modern well designed amp on, no matter what the origins.
I've been trying to find older iron for both power and output. My latest MEC ( mouse electric chair) project is based on 6LU8 family in the Dynaco St70 topology. Main difference is in the feedback. The Bogen output iron is 6.6KRaa which allows for more class A output, yes less overall power and the PT is from an organ donor. Large iron with 12Vct heater winding. All iron stays cool after 8hrs of thrashing. Sweep tubes in place of the 6L6 based tubes. I used .22u PIO to couple the cathodyne to the outputs. Diode and large cap power supply allows for the low end to breath. The 6LU8 family are 14 watt tubes and can perform at higher than rated levels ( some not all). This proves the basic St70 topology is very good. There are just many ways to implement it with their trade offs.... Dynaco chose theirs and I chose mine...
The next PCB is again the basic St70 topology, but with 17JT6 and 18GB5 output tubes...
The next PCB is again the basic St70 topology, but with 17JT6 and 18GB5 output tubes...
Attachments
Hi i have a Dynaco vta st-120 from bob latino . It has the low gain board :12bh7a or the 12au7 in the pre stage ,and it will use 6550's or kt-88's or kt-90's and it will also run the kt-120 power tubes.I have three pairs of klipsch speakers .and i also have a rebuilt original st-70 and a modified st-70. and these are very nice amps. and all three are very stable and dependable .also just one last note in my humble opinion nothing is more MUSICAL than vinyl and tubes and horns......HANDS DOWN....
VTA board
I wanted to warn anyone thinking about a Dynaco st-70 upgrade. Stay away from the VTA 6sn7 board. With the oversized caps. It simply does NOT fit. The silkscreen info that was on older boards is gone. The instruction are vague with few illustrations.
I've used the triode board & the Curcio (excellent documentation) both are great.
I email Bob at Vta and got a remarkably pandering reply. Rather than addressing the issues I pointed out he sent me 2 reviews allegedly from users telling how great his product was. Not one word on the issues I brought up.
I've been building my own gear for 40+ years & have dealt with a number of remarkable & helpful people. I will never buy another VTA product.
I wanted to warn anyone thinking about a Dynaco st-70 upgrade. Stay away from the VTA 6sn7 board. With the oversized caps. It simply does NOT fit. The silkscreen info that was on older boards is gone. The instruction are vague with few illustrations.
I've used the triode board & the Curcio (excellent documentation) both are great.
I email Bob at Vta and got a remarkably pandering reply. Rather than addressing the issues I pointed out he sent me 2 reviews allegedly from users telling how great his product was. Not one word on the issues I brought up.
I've been building my own gear for 40+ years & have dealt with a number of remarkable & helpful people. I will never buy another VTA product.
Re: "I email Bob at Vta and got a remarkably pandering reply" You never Emailed me - you Emailed Roy Mottram. I have dealt with Roy for the past 8 years and all my dealings with Roy have been stellar. If you can't get that board mounted correctly maybe you should post a photo of how "the board does not fit properly" so we can all see why the board does not fit ? I know that Roy has sold MANY octal driver boards. Below is a photo of an octal board that has been added to a stock ST-70. It fits fine ..
Bob Latino
Bob Latino
Dale never asked any questions, just started posting complaints.
You can see the photo in the previous post by Bob of a customer built
octal VTA70, but Dale can't seem to do what 2000+ other extremely happy
and satisfied users have done without problems . . .
tube4hifi ST70 page
You can see the photo in the previous post by Bob of a customer built
octal VTA70, but Dale can't seem to do what 2000+ other extremely happy
and satisfied users have done without problems . . .
tube4hifi ST70 page
BTW, here is a comment I received from another customer about 3 months ago regarding the VTA70 octal board . . . .
Hi Roy,
Just wanted to let you know that I got the amp up and running, and it sounds great. I’m very happy with the 6SN7 board. I did some quick measurements on the completed amp and they were better than I expected.
Here’s what I got:
Max power before clipping 40W
Response @ 40W +/- 1db 20Hz-30kHz
THD @ 20W .12% @ 1kHz .15% @ 20kHz .45% @ 20Hz
As far as sound Vocals are outstanding. The overall sound has a nice balance of warmth without loosing detail.
Very good soundstage in both width and depth.
I congratulate you on a fine upgrade to the old Dynaco work horse and I thank you for your quick responses to my Emails during the assembly process.
Bill K
Hi Roy,
Just wanted to let you know that I got the amp up and running, and it sounds great. I’m very happy with the 6SN7 board. I did some quick measurements on the completed amp and they were better than I expected.
Here’s what I got:
Max power before clipping 40W
Response @ 40W +/- 1db 20Hz-30kHz
THD @ 20W .12% @ 1kHz .15% @ 20kHz .45% @ 20Hz
As far as sound Vocals are outstanding. The overall sound has a nice balance of warmth without loosing detail.
Very good soundstage in both width and depth.
I congratulate you on a fine upgrade to the old Dynaco work horse and I thank you for your quick responses to my Emails during the assembly process.
Bill K
Just my opinion
I notice the only loyal customers to reply were the owners. Again, if you are thinking about upgrading I personally would avoid VTA. What I stated in my first email is accurate and I stand by it.
If you are upgrading I would advise you to weigh your option carefully.
One last note of all the Dynaco products available for the st-70 only the folks at VTA go out of their way to slam the competition. This alone should have told me what they are about.
I notice the only loyal customers to reply were the owners. Again, if you are thinking about upgrading I personally would avoid VTA. What I stated in my first email is accurate and I stand by it.
If you are upgrading I would advise you to weigh your option carefully.
One last note of all the Dynaco products available for the st-70 only the folks at VTA go out of their way to slam the competition. This alone should have told me what they are about.
Since you are going to put out a chunk of change I would suggest looking at the Mapletree Stealth Mono blocks. Sure their a little more money but after hearing both the tubes for hi fi and the Mapletree I would go for the Mapletree.
Years ago I also purchased a tubes for hi fi driver board. It sounded good but after about 50 hours I found some resistors were running too hot and discolored. I sold the amp and purchased another one. The newer amp had all the goodies a big power transformer and new output transformers and choke.
I ended up rewiring it putting a Triode Electronics power supply board and a Mapletree Driver Board. I found this amp very pleasing to listen too. I liked the 6SJ7 input tube and the long tail 6SL7.
Years ago I also purchased a tubes for hi fi driver board. It sounded good but after about 50 hours I found some resistors were running too hot and discolored. I sold the amp and purchased another one. The newer amp had all the goodies a big power transformer and new output transformers and choke.
I ended up rewiring it putting a Triode Electronics power supply board and a Mapletree Driver Board. I found this amp very pleasing to listen too. I liked the 6SJ7 input tube and the long tail 6SL7.
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