My first project.

knowledge base for the classic Dynaco ST70

Postby TomMcNally » Tue Mar 01, 2011 11:14 am

MrMiele wrote:Received transformes and choke today. What is the difference PA060S power transformer vs PA060 ?


I think the "S" is Triode's suffix for "Super" bigger, better, runs cooler, etc
User avatar
TomMcNally
Darling du Jour
 
Posts: 2729
Joined: Sat Nov 19, 2005 2:19 pm
Location: Northfield, NJ

Postby MrMiele » Wed Mar 02, 2011 6:13 pm

Update: Here is first mockup.

Image

Image
MrMiele
 
Posts: 26
Joined: Tue Feb 08, 2011 5:59 pm
Location: Los Angeles, CA

Postby TomMcNally » Wed Mar 02, 2011 6:20 pm

Is the power transformer back as far as it can go?
Your rectifier is going to have a short life being so close,
it would be nice to have more airflow.
That's a big ass transformer! Good stuff.
User avatar
TomMcNally
Darling du Jour
 
Posts: 2729
Joined: Sat Nov 19, 2005 2:19 pm
Location: Northfield, NJ

Postby MrMiele » Wed Mar 02, 2011 6:36 pm

TomMcNally wrote:Is the power transformer back as far as it can go?
Yes. :(
MrMiele
 
Posts: 26
Joined: Tue Feb 08, 2011 5:59 pm
Location: Los Angeles, CA

Postby Ty_Bower » Wed Mar 02, 2011 8:47 pm

This probably isn't what you want to hear, but you ought to consider a larger chassis. It would be better to have enough real estate to build the amp you want, rather than regretting trying to squeeze everything on. Perhaps you could resell the chassis you already have, or better yet save it for another (smaller) project - maybe a Stereo 35 would fit nicely on it?
"It's a different experience; the noise occlusion, crisp, clear sound, and defined powerful bass. Strong bass does not corrupt the higher frequencies, giving a very different overall feel of the sound, one that is, in my opinion, quite unique."
User avatar
Ty_Bower
KT88
 
Posts: 1494
Joined: Wed Mar 21, 2007 2:50 pm
Location: Newark, DE

Postby MrMiele » Wed Mar 02, 2011 10:44 pm

Ty_Bower wrote:larger chassis

Any samples, links for larger chassis?
Thanks!
MrMiele
 
Posts: 26
Joined: Tue Feb 08, 2011 5:59 pm
Location: Los Angeles, CA

Postby Quad » Wed Mar 02, 2011 11:34 pm

If you really want to use that chassis, you could house
the PT in an old PC SMPS case, and make a custom
cable (perhaps with octal plugs) to connect it to the amp.
The cable and connectors must be rated for the
B+ voltage.
Quad
KT88
 
Posts: 253
Joined: Mon Jan 14, 2008 6:54 am
Location: India

Postby MrMiele » Thu Mar 03, 2011 10:57 pm

Thanks guys for your advices. I really like this chassis and will stay with it.
Redesigned back panel and pushed PT 1" away from rectifier.
Will start drilling on the weekends. =:o
Image

Image
MrMiele
 
Posts: 26
Joined: Tue Feb 08, 2011 5:59 pm
Location: Los Angeles, CA

Postby MrMiele » Sun Mar 20, 2011 10:59 pm

Drilling and cutting started. I like unibits.

Image
MrMiele
 
Posts: 26
Joined: Tue Feb 08, 2011 5:59 pm
Location: Los Angeles, CA

Postby MrMiele » Sun Mar 20, 2011 11:11 pm

I have a question regarding wiring diagram. It's looks like polarity of capacitors wrong in the red box.
Please correct me.

Image

Thanks.
MrMiele
 
Posts: 26
Joined: Tue Feb 08, 2011 5:59 pm
Location: Los Angeles, CA

Postby Quad » Sun Mar 20, 2011 11:42 pm

That's the bias supply (negative with respect to ground - note
how the diode is connected), so the polarity of the caps
in the schematic is correct.
Quad
KT88
 
Posts: 253
Joined: Mon Jan 14, 2008 6:54 am
Location: India

Postby MrMiele » Wed Mar 30, 2011 10:37 pm

Hi guys, here is update:
All covers from transformers sandblasted, primed and painted.

Before:
Image

After:
Image

Next to wood side covers
Image

Side wood covers look good to me after WATCO Oil finish
Image

And here is big boss:
Image

So, most parts ready to be assembled. I just have to paint main chassis. Don't know what color to choose, probably satin black...
MrMiele
 
Posts: 26
Joined: Tue Feb 08, 2011 5:59 pm
Location: Los Angeles, CA

Postby MrMiele » Wed Mar 30, 2011 10:39 pm

..forgot to show how this:

Image


Took me couple hours to make it happen.
MrMiele
 
Posts: 26
Joined: Tue Feb 08, 2011 5:59 pm
Location: Los Angeles, CA

Postby Ty_Bower » Wed Mar 30, 2011 11:42 pm

Nice looking work so far. You've got pretty good aim with a drill and a unibit. It seems all the holes have ended up precisely where you intended. Is there any concern about the conductive nature of the trimpot screw, and whether it might contact the chassis?

I do like Watco oil too. I can't quite remember who first showed me the stuff, but it is so easy to use and almost always turns out looking fantastic with minimal effort.

I can't wait to see the completed amplifier. Good job!
"It's a different experience; the noise occlusion, crisp, clear sound, and defined powerful bass. Strong bass does not corrupt the higher frequencies, giving a very different overall feel of the sound, one that is, in my opinion, quite unique."
User avatar
Ty_Bower
KT88
 
Posts: 1494
Joined: Wed Mar 21, 2007 2:50 pm
Location: Newark, DE

Postby MrMiele » Tue Apr 05, 2011 11:28 pm

Today was first startup, no sparks and smoke ;)
Here few pictures:

Image

Image

Image

Next step is tubes bias adjusting.
If you guys have some tips or recommendations for me, please share it.
Thanks.
MrMiele
 
Posts: 26
Joined: Tue Feb 08, 2011 5:59 pm
Location: Los Angeles, CA

PreviousNext

Return to st70

Who is online

Users browsing this forum: No registered users and 17 guests