Hello Everyone!!! ~VTA ST-70 Build~

I just wanted to take a moment to say hello to everyone here. I have been reading through the pages here for a few months and I have found this site to be a very valuable resource. I hope one day I can contribute something that will help others as I have been helped here.

Let me tell you a little about myself and the system I am putting together...

I went to school to be an automobile mechanic. Currently I live on the edge of Detroit, and work on the development of prototype vehicles for one of the many big companies here. I have almost no experience building electronic kits. I also have little to no experience with tube amps or 'Hi-Fi' sound systems. I have been a DJ and a record collector for a long time. These days I am really just a record collector and listener. I have a big record collection and a loud PA system that for years I have used to play music at home. Aside from a turntable, the only other audio source I use is a (low quality) digital source. I either plug in my laptop or my phone and listen to MP3s or I stream Pandora or some other form of internet radio or podcast.

Earlier this Summer, I was given an old pair of Ohm D2 speakers in excellent condition. I plugged these into the only amp I had to run them... Some old solid state Kenwood home theater amp that I was using in my garage. I plugged in a Technics SL-1200MK2 turntable with a Shure M97xE MM cartridge to the phono stage of the Kenwood. Record after record, I was really surprised how much better this set-up sounded than my "loud-speaker-sytem". My records had new life! I mean really, I was surprised by what I had been missing!

So, I started looking for a sweet amp to drive these speakers. After a bit of research I decided I would build a VTA ST-70 kit w/ cap upgrades. I then got in touch with Roy and after a bit of discussion decided to have him build me a VTA SP12/PH12 preamp.

Up until now I have had very little to add to this site, but since there was a bit of lead time for Roy to order parts and build the preamp, I thought I would take my time with the ST-70 build and take a lot of photos to document my progress.

From beginning to end Bob's kit is an absolute pleasure to build!!! His instructions and pictorials are concise and easy to follow. It is also very reassuring to know that Bob is just an email away. I did email him a couple of times with questions, and I don't think I ever waited more than 10 minutes for an answer. That is AMAZING customer service!!! Thanks Bob!

Thanks to everyone here for their contributions!!!

So the build has been done for a week or two but I am just finding some time to type some words and post some photos.

Bobs kit arrived fast, safe, and carefully packaged!



This was about as far as I got the first day... Like I said, I was taking my time.

Since I feel I am a bit more mechanically inclined than electronically inclined I decided to put the driver board to the side and begin assembly of the amp and hardware.



Tube sockets and rear panel hardware installed.


I spent a LOT of time throughout the build "clocking" the flat head screws provided with the kit. Call me crazy, but I cannot stand having flat heads pointing in all different directions (I didn't clock the transformer screws and it is bugging me now). I am not a fan of all the flat head screws in this kit, and it is perhaps the only thing about the kit that I would change. I was terrified the whole time that the screwdriver was going to slip and scratch the chassis (it happened once or twice). If I were to do it again I would go to my local fastener supplier and buy some nice stainless button head hex bolts to replace the flat heads provided.

Ok. Time to get busy.

Power transformer and choke installed


Output transformers installed


Quad cap install
Ok So I found this to be a scary part, I was afraid to twist the locking tabs.


Twisting wires


I took some time to route all the wires like the pictorial before I actually started cutting anything.


This is where I ended the build for the day... I had a few drinks while I was twisting and routing wires. I decided that I would re-check everything in the morning before I started cutting wires!!!

After triple checking everything. I trimmed all the transformer wires to the appropriate lengths


Lots of connections made! Ready to wire up the triode/pentode switches.


I precut and bent the additional wires for the switches


Left switch done


Right switch done


Quad cap wired


More wires, resistors, & caps added.


At this point, the amp is ready for the driver board installation.

Time to build the driver board.


I think it took me longer to REALLLY make sure that my tube sockets were level, than it did to build the rest of the board!!!






The driver board was very easy to build, with excellent instructions and packaging. Having very little electronics experience I was pleasantly surprised by how fun and easy it was to build this board!

OK, Lets get that board into place!!! At this point the excitement builds as I can feel I am getting close!


Front panel hardware installed and inputs connected

Bob warns you in the instructions that some if these nuts are a challenge to put on. Well, he is not kidding! Especially if you are crazy like me and must have your screw slots perfectly vertical!

Connections made to the driver board


Wiring Complete!!!


Time for some testing! and a drink!!!


I plugged in some cheap bookshelf speakers for the initial fire-up procedure, and followed Bob's instructions for bringing my new creation to life.


It worked!

Everything worked perfectly! First Try! It even sounded pretty good plugged into my laptop and playing through the little speakers! Plugged into the Ohms it REALLY sounded nice, even without a preamp. I couldn't be happier with this amp, or the experience of building the kit!



I will post a link to all the full size photos from the build as soon as I am able. I am new here so I cannot post links


Thanks for viewing!
-Mike

Mike,
super nice post with great photos!! thanks.
Roy

Love the cat. Congrats on such a well planned and clean build. I especially admire those builders who take the time to think ahead and route their wires correctly and cleanly even though they are not visible. My Dynas were all built by someone else and dear God they are a mess. Perhaps for a winter project I may sit and rewire them just because they drive me nuts the way they look. Would also be a chance to upgrade to a new board as well. Again, a job well done. Enjoy the sound of your new amp.

I'm envious of the way you have meticulously put together this beautiful amp. clearly it should be an example for me to to improve my own internal wiring
very well done!

Very nice and clean job!! Congrats!!
BR,
Danskman

I love the work bench layout shown in the first photo of "building the driver board": Soldering Iron, hookup wire, components, instructions and a large mug of black coffee .

You said at the beginning "I hope one day I can contribute something that will help others" well I do not have an ST70 but I do have a couple of MK3s and peoples' build photos, like those of your ST70, as well as photos of completed builds have certainly helped me.

Well done and thank you.

Thanks for the kind words everyone! I have really been enjoying this AMP!!! (I understand about the screws Bob, it's OK)

So far, I have been using all the tubes supplied by Bob, but I think soon I may try out the matched quad of NOS Russian 6P3S-E output tubes I bought from Jim McShane a while back. I will report back if I notice any big differences.

-Mike

Congrats on a great build.

Your excellent photo- documentary of the build will definitely encourage and assist future builders who might be soldering-gun shy!

Part of the thrill of this amp is when friends look at this retro thing with obvious doubt. A cold war relic is it? And then their jaws drop when they hear it.

Congrats on your great build. My experiences with the purchase, build and customer service match yours exactly. Bob's VTA ST-70 kit is one of the outstanding products available to the DIY market. Your IC cables remind me of the White Lightning DIY cables.

Nice build.
I hope to build a pair of M-125's this year and I hope they turn out as nice as your ST-70 build.

Tube Nube wrote:Part of the thrill of this amp is when friends look at this retro thing with obvious doubt. A cold war relic is it? And then their jaws drop when they hear it.

I get the same reaction from family and friends.