Point To Point, No Kit

How (where) can I get either instructions, diagrams, or teachings to assemble from scratch an ST70 ? What I mean is to not use a kit. Therefore, I myself would acquire the individual parts from any number of sources...Including, resistors, caps, chockes, transformers, chasis, sockets, and etcetera. I would like to do this without circuit boards (no PCB, neither for driver board nor for power supply cap board) and simply do it all one hundred percent point to point with wires.

I would still like to find a way to build it as above even though I have received the following advice;

1) begginers should start with a kit not P2P
2) this is more dangerous
3) this is far more difficult
4) it won't look as nice (e.g. your chasis will be ugly, etc)
5) there's no advantage to doing it like that
6) this will take you so much longer
7) kits are proven and there's more support
if you have to ask how, then you should not be attempting this (<-- that's a good one)
9) ....and much much more

yes, I'm a little determined (or stubborn) and I appologize for that...but nevertheless, if you know of any resources or have thoughts that might help me achieve my goal, that would be hugely appreciated.

Kind thanks,
Eddie

Hi again,

as said in audiokarma, go for it. Expect the need for restarts, each build will be better then the previous.

They don't call it DIY for nothing.

This is an ST-35



This is MY ST-35

corndog71 wrote:They don't call it DIY for nothing.

This is an ST-35



This MY ST-35

and how does it look from below ??

peterh wrote:
and how does it look from below ??

Sorry that it's kind of dark.  It's really hard to get a good pic of the inside due to the aluminum box reflecting the flash.  And I took this with my phone.



Full-size version

Sourcing materials can be ... interesting. I'd think your biggest problem would be transformers. The Latino units are custom wound to improve on the original design's capacities and outputs ... I imagine one off orders would be cost prohibitive. From there, it devolves to digging thru piles of junk amps looking for the right specs and hoping they're working right when you get em  ...luck with that, eh.

I thought about doing the same but went with a kit. Still managed to have fun with it and ended up with something a bit off the beaten path ... put your mind to it and you can still end up with something unique and one of a kind.

PS ... schematics aren't really a problem ... those are all over the web ...

If you are talking about the original ST70 just make a copy of the manual and go to work. The manual contains a schematic. There is a copy in the sticky area of this board. If you want an updated driver board [I would] then contact the individual sellers to see what they would charge for a schematic and parts list for there board. I think Tube4HIFI charges $39.00 for a blank board, free shipping and instructions. A bargain. I know you don't want to hear this but by the time you buy all of the parts to build it you will have almost as much as a complete kit invested and your finished kit will be hard or next to impossible to sell. Just my 2 cents.

Eddie,

This is almost what I did.  I sourced new parts from all over the place and assembled a "kit" to which I followed a copy of the manual to assemble a knock-off of an ST70.  I used a board from Triode Electronics which used the circuit from the original 7199x2 board, but did it with 6AU6Ax2 and a 12AU7A/12BH7; the rest were new parts like repro chassis, top cover, transformers, etc...

If I knew that I could have bought a kit, then I wouldn't have hesitated to go that route instead.  You may want to buy repro transformers (many sources such as Triode, Dynakitparts, Bob Latino, etc...) then design your chassis, assemble the rest of the components since that involves sockets, tubes, resistors and capacitors, etc... fairly straight forward.  Leaving off the board then involves using the tube sockets as tie points, and adding terminal strips to complete assembly, and if you have never done this before, it can become very confusing.

I don't really think that would be the best way to go.

And Sailor is right; if you ever decide to sell your amp, it will be met with skepticism as to how good it is just based on looks alone.

Tony

sKiZo wrote:Sourcing materials can be ... interesting. I'd think your biggest problem would be transformers. The Latino units are custom wound to improve on the original design's capacities and outputs ... I imagine one off orders would be cost prohibitive. From there, it devolves to digging thru piles of junk amps looking for the right specs and hoping they're working right when you get em  ...luck with that, eh.

I thought about doing the same but went with a kit. Still managed to have fun with it and ended up with something a bit off the beaten path ... put your mind to it and you can still end up with something unique and one of a kind.

PS ... schematics aren't really a problem ... those are all over the web ...

I'm sure Bob wouldn't have any issue selling someone just the transformers. I've bought partial kits from him before for customs, as have others. There are other sources as well.

OT: Did you get your bias meters working?

My second tube amp build was point to point. I learned a TON about how it all works, mainly because mine was noisy on the first try. I ended up moving, rewiring, improving and modifying. Once I got it to work I started over again with a bunch of ideas on improvements. I ultimately made my own turret board to simplify the wiring and to make modifying and testing easier.

At the end of the day, I spent more money and way more time, but I would do it all over again. In fact I have on a couple of occasions! I love my VTA st70's and enjoyed that process too. I learned way more designing and troubleshooting my point to point amps. If you're patient, careful and want to learn, it's the way to go. If you want a well designed, magnificent sounding amp buy a good kit, or at least a good PCB.

Make sure you discharge those caps & keep one hand in your back pocket!

Are you guys calling my amp ugly?  

I don't think eddie's intention was to resell the amp. Thus future resale value ( or total economy ) is a non issue.

But i need to respect a person that is willing to climb a steeper mountain ( which i have done myself a loong time ago) with one of the goals to learn. It's not impossible, far from, it's not dangerous and it's not illegal. It _might_ not be the best amp this time, but it sure will be a learning experience for life!

One advice could be to have a look at those Fender amp kits that is available ( or a fender in general if he has access), here tube holders and turret boards are used and components are surprisingly pretty mounted. Given enough space one could use that technology, i doubt it could be made pretty on the area available in a st-70. But it don't have to be a st-70 size, it could be more spacious .

One neglected strong benefit of building p2p is the ability to modify much more easily, testing new circuits is a matter of cutting and soldering.

Eddie: go for it !

peterh wrote:I don't think eddie's intention was to resell the amp. Thus future resale value ( or total economy ) is a non issue.

But i need to respect a person that is willing to climb a steeper mountain ( which i have done myself a loong time ago) with one of the goals to learn. It's not impossible, far from, it's not dangerous and it's not illegal. It _might_ not be the best amp this time, but it sure will be a learning experience for life!

One advice could be to have a look at those Fender amp kits that is available ( or a fender in general if he has access), here tube holders and turret boards are used and components are surprisingly pretty mounted. Given enough space one could use that technology, i doubt it could be made pretty on the area available in a st-70. But it don't have to be a st-70 size, it could be more spacious .

One neglected strong benefit of building p2p is the ability to modify much more easily, testing new circuits is a matter of cutting and soldering.

Eddie: go for it !

All of you are contributing very rational things to my topic and I don't disagree with any of you. It's just that I have my heart set on learning via this method. Resale is definitely not a concern. In fact, I will have no regard for what it looks like for this first one (the only goal is sound quality and I'm willing to fail a few times due to the way that I learn). I learn so profoundly from my mistakes that I gain priceless knowledge. I have two main objectives; One is to learn as much as possible because I want to fast track to the point where I can eventually design my own tube amp and get it sounding like a $30,000 amp (while spending something less than $5,000). Secondly, I want to save as much money as possible on the first few attempts because I'm paying more for the education rather than my final dream amp.

Not sure If it makes sense but I kinda like the way Peterh put it.

And I take what each of you say very seriously and I have genuine appreciation and thankfulness towards all of you.

I have to say I like a challenge and to do things my way so I say go for it!
After much research and studying schematics I ended up buying an VTA ST-120 from Bob and had every intention of assembling in a custom enclosure with a few modifications however after several Months into the build I couldn't wait any longer and built the OEM kit and could not be more happy at 70 hours and counting.

Another option is to refurbish an old point to point amp like some of the early Heathkits. The EA-3's are pretty straight forward and have a preamp. The A7's aren't too bad but don't have a preamp. These are both mono amps though. For stereo, the SA-2 and AA-151 are both point to point but a little crowded. I refurbished an SA-2 last year for my dad. It was a lot of fun...but not as much fun as building the Latino ST-120, nor did it sound as sweet!

[quote="EddieGnz1"]

peterh wrote:I want to save as much money as possible on the first few attempts because I'm paying more for the education rather than my final dream amp.

That's realistic, not expecting to build your dream amp on the first try.

As a first scratchbuild, consider something simpler than a Dynaco stereo amp; perhaps a mono single-ended triode.
Many hobbyists build their own and there are several forums about DIYing them. There are some minuses, though:
low power, perhaps not usable with your loudspeakers being one; the "power is everything" wall-shaking rock music
brigade will not be impressed; but you'll still learn a lot from trying out one, and you could wind up with the best
workshop amplifier imaginable.

Being mono isn't a real problem; if it turns out you like it once you've got one sorted, you can clone another one.

One possible issue is that with the right loudspeakers, a single-ended triode might spoil you for other amplifiers.

I post on more than one board. On one of those boards I spend most of my time helping first time kit builders get there kits working. Some of those kits are point to point wiring. Here are some of the problems I have had with first time builders. Poor solder joints, solder runs that short the circuit, electrolytic caps installed backwards, parts and wires installed to the wrong location, diodes installed backwards, parts or wires not installed, selector switch internally damaged by the soldering iron and many other problems. When I give advise I find that many don't know the purpose of the individual parts nor do they know how to read a schematic and many don't even own a volt/ohms meter.
I understand what you are trying to do however know this I built my first point to point 5 tube radio from scratch when I was 14 years old. I am now in my 60's. I have scratch built, built kits, modified preamps and amps and even redesigned a few circuits. This is what I learned. If you want to some day design your own amp you will not learn how to do that from a kit or from building a scratch build amp. That will only teach you how to put electronics together. The knowledge you seek is learned from books because you first need to know what each part does and then you need to know how to size each part fit into a given circuit. Again, just my 2 cents.

sailor wrote:Here are some of the problems I have had with first time builders. Poor solder joints, solder runs that short the circuit, electrolytic caps installed backwards, parts and wires installed to the wrong location, diodes installed backwards, parts or wires not installed, selector switch internally damaged by the soldering iron and many other problems.

Guilty of pretty much all of those.     I've only been doing this stuff for around 15-16 years and learned a lot of it by trial and error with a little help from Bottlehead and Joe Curcio's forum.  I do agree that I learned very little about circuits when rebuilding my already rebuilt ST70.  But I kept reading and asking questions and eventually learned to read schematics and how to solder properly.

I learned a lot more by taking the ST35 circuit and figuring out how to add a relatively new bias circuit along with another guy's driver circuit.  Reading an old RCA Tube manual filled in a lot of background info that I think was more common knowledge back in the day.  I''m still a little shady on the math and technical details but I'm looking forward to getting an oscilloscope and learning how to use that.  Sure, I could've learned that stuff sooner but this is my hobby and I'm learning at my pace.