Upgrading Dynaco ST-400

[boostin1989]

I have a Dynaco ST-400 that seems to be all original. I would like to go through and upgrade it with some newer components. I plan on replacing some of the capacitors, certain resistors and bypass the Dynaguard. I'm not an electronics "expert" but I can get by. What else should I do while I have the amp apart? Anyone have any info any problem areas that should be addressed with this amp?

 

[audiobard]

dynaco update

Hello,

There is an article in TAA (The Audio Amateur) 3/83 by Bill Rollins about an update of the stereo 400. I have a copy on paper, but not yet in electronic form.I'll try to scan it as soon as I can and mail it to you if you are interested.
All best

 

[d3imlay]

If this was a kit built unit, the build quality is suspect. Look for poor/improper connections and bad solder joints.

 

[gunsoftexas]

More juice

This could help you

 

[bigyank]

Hello,

There is an article in TAA (The Audio Amateur) 3/83 by Bill Rollins about an update of the stereo 400. I have a copy on paper, but not yet in electronic form.I'll try to scan it as soon as I can and mail it to you if you are interested.
All best

I am getting ready to dive into a ST-400 rebuild and wondered if this article you reference was ever scanned in?

Yank

 

[audiobard]

Hi bigyank,boostin1989
Pls send me your e-mail.

 

[bigyank]

I just did thanks for getting back to me.

Yank

 

[lowpoke]

Or if you really want to change it up some, you can give it a $1300 Van Alstine makeover.

 

[audiobard]

Bigyank check your inbox )

 

[bigyank]

Got it thanks. I am definitely aware of Frank's work and the Insight amp. My issue is that my amp has the meter option and I would miss them.

Yank

 

[lowpoke]

My issue is that my amp has the meter option and I would miss them.

I could always take those meters off your hands for you. They'd look awesome in the front of my 410

 

[bigyank]

I could always take those meters off your hands for you. They'd look awesome in the front of my 410

Nope........

An externally hosted image should be here but it was not working when we last tested it.

Not a great shot but this unit is pretty clean considering her age......

 

[tolaughlin]

I have a Dynaco ST-400 that seems to be all original. I would like to go through and upgrade it with some newer components. I plan on replacing some of the capacitors, certain resistors and bypass the Dynaguard. I'm not an electronics "expert" but I can get by. What else should I do while I have the amp apart? Anyone have any info any problem areas that should be addressed with this amp?

Can I get a copy of the Audio Amateur article on the Dynaco ST-400? I was just given a blown unit and as long as I'm going to fix it, I may as well upgrade it.

 

[Krisfr]

I just found out that I have the chassis and heat sink for a 400 like the one in post #12 I am thinking of which way I should go with what I have, I gave away the output trans about a year ago, and do not know if it is worth the time and trouble to bring it to life. I do not have the driver board or out put transformer, which are essential. I have the input board and a few other parts. I am open to suggestions.

 

[wg_ski]

It's a nice roomy chassis, suitable to build your choice of amplifier into. Starting with an existing chassis is a whole lot easier than starting from scratch when building a new amp. If you don't have the trafo, a toroid would be a nice upgrade anyway. You need 53-0-53, give or take a couple of volts. Go lower (50-0-50) and use >1kVA and you will be fine. A similar topology driver circuit could easily be built with modern parts or you can go with something all new. The heat sink can be drilled to accomodate extra output pairs (recommended).

 

[maqm]

Gentlemen:

Someone can confirm if: 150 mA is the correct value to calibrate properly the bias in the Dynaco ST 400?

Thanks