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John W
07-29-2005, 12:00 PM
I was just about to put my two cents in on a separate thread discussing amps from the 70s and 80s when the thread was closed. So, here goes a new discussion.

I have used various amp/preamp or integrated amps from this era, both tube and solid state, including vintage Yamaha ns, Dynaco and Pioneer sx models. To me, nothing compares to my DIY amps I built from here.

http://sound.westhost.com/project101.htm (http://sound.westhost.com/project101.htm)

I built both a 240w/ch and an 80w/ch version. They are dead quiet till the signal hits then they just sing. My ears could be colored somewhat with the pride of constructing it myself, but so what, thatís what I like about this hobby.

Lancer
07-29-2005, 12:15 PM
Let's see some pictures! :)

I like Rod Elliott's projects.

John W
07-29-2005, 12:16 PM
I will post some tonight. They don't let me bring the stereo equipment to work.:D

John W
07-29-2005, 07:53 PM
Here is the high power one. The front is a carbon fiber panel that I had from another project, the sides are some salvaged heatsinks and the rest is 1/8 aluminum from Boeing surplus. It would be better if the heatsinks ran vertically but the amp stays suprisingly cool, so it isn't an issue.
It has a large toroidal transformer. Main filtering is 4 25000uf salvaged computer caps and then 2 4700uf for each channel. Once you switch it off, it keeps playing for another couple of minutes on its own.

John W
07-29-2005, 07:56 PM
Here is the smaller amp. It is built on a Dynaco 120 chassis that had a busted channel. There really isn't much left of he original amp. The Dynaco never sounded so good.

Zilch
07-29-2005, 10:26 PM
WHOA! Mondo TOROIDUS :thmbsup:

Those're MIGHTILY cool.... :applaud:

pmakres1
07-29-2005, 10:28 PM
Your high power amp is way cool!

And oh yes, those are the most unusual Stereo 120 innards I've ever seen! :applaud:

In my youth I built a Stereo 80, 2 PAT-4's and I had a factory assembled Stereo 120. The Stereo 120 was a lemon and a half...to the best of my knowledge the Stereo 80 still works today! (my brother has it).

At least you got some use from the 120 chassis!! :D

Peter

Wardsweb
07-29-2005, 10:54 PM
I've never tried to build a solid state amp. All my stuff has been tubes. From custom one off creations

http://wardsweb.org/LSB/08_09_03/08_09_64.jpg

to modifed kits

http://wardsweb.org/LSB/01_17_04/gear/02.jpg

pelly3s
07-29-2005, 11:09 PM
hmmmm that gives me an idea with my st-120 chassis, I bought one for $75 and the thing met its match when it got hooked to a speaker with a dead short in the crossover. I hated the sound of the thing anyways. Those are some cool looking toys. If I only had money lol

Ian Mackenzie
07-30-2005, 01:42 AM
Nice job John,

Yes Rod Elliott does pump out good projects.

Here's a snap of my 1st diy amp, an Aleph 2 clone (Passlabs).

Makes a great foot warmer in winter and you really can't beat the sound if you don't mind burning 300 watts at idle!

This little one is my favourite, pumps out 37 watts in 8 ohms, 70 into 4 ohms and is biased at 8 amps. Nothing touch's the sound.

Ian

John W
07-30-2005, 08:46 AM
Those are some nice tube amps. Where did you find the nice chrome chassis for your top picture?

Alex Lancaster
07-30-2005, 09:28 AM
:applaud: All of Your DIYīs look great, wish I could do that.

bbrown
07-30-2005, 11:07 AM
About 30 years ago I got an ST-120 and an ST-70 from a friend. I sold the ST-120 a couple of years later. I still have the ST-70, although it has been rebuilt. The ST-120 is probably in a landfill by now.

pmakres1
07-30-2005, 11:28 AM
About 30 years ago I got an ST-120 and an ST-70 from a friend. I sold the ST-120 a couple of years later. I still have the ST-70, although it has been rebuilt. The ST-120 is probably in a landfill by now.

From my own experience and from nearly everyone else I've heard from, the Stereo 120 simply was not a reliable design. :no:

Peter

bbrown
07-30-2005, 12:40 PM
I have been tempted to build an amp based on Marshall Leach's design for his engineering calss. It is supposed to be very good. You can check out the design here:

http://users.ece.gatech.edu/~mleach/lowtim/

Bruce

Ian Mackenzie
07-30-2005, 03:21 PM
Its a good design but a bit dated.

http://www.aussieamplifiers.com/av800.htm

Never built any but if you want brute power ..........

John W
07-30-2005, 07:56 PM
If anyone is looking for some extra Dynaco Stereo 120 stuff, I got a box full. No-charge.
A major problem I saw with the 120 was that the outputs fed through a big electrolytic capacitor-inductor assembly. One of these had failed on the amp I had. They probably didn't help the sound in the best of times.
I probably would have reused the transformer, but it doesn't have a center tap. Only a single supply rail.

Wardsweb
07-31-2005, 03:23 PM
Those are some nice tube amps. Where did you find the nice chrome chassis for your top picture?

They are not chrome, but polished aluminum that I picked up from International Audio Group (http://www.iagaudio.com/). Horace is the same guy I got the polished transformer covers from.

Here is a shot of the inside of the custom 2A3 amp.

richard c.
07-31-2005, 09:01 PM
John W,

Have you had any takers on the Dynaco ST120 parts. I have two of these amps, which I have had to do extensive restoration on. After several replacement transistors and TWO output caps, I have two decent power amps. I also have a Hafler DH200, and two Dynaco MKIII monoblock amps.

Since I can't help myself in liking old Dynaco stuff, I would like these ST120 parts - especially the power transformer and the circuit boards. I will pay shipping costs, naturally.:)
Richard C.

John W
08-01-2005, 08:06 AM
Sure thing. Check for a private message.
I like the Dynaco stuff too. I have a couple MkIII amplifiers and just recently a very nice St70.

pmakres1
08-01-2005, 09:13 AM
They are not chrome, but polished aluminum that I picked up from International Audio Group (http://www.iagaudio.com/). Horace is the same guy I got the polished transformer covers from.

Here is a shot of the inside of the custom 2A3 amp.

This looks like a very, very nice job. Very neat and orderly. This makes me want to do a DIY amp myself...something I have always had an interest in doing. I never got around to it, aside from building those Dynaco kits 30+ years ago.

Nice work! :applaud:

Peter