ST70 Clone - point to point wiring.... ITS ALIIIIIVEEEEE

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ST70 Clone - point to point wiring.... ITS ALIIIIIVEEEEE

Postby parabellum » Mon Aug 13, 2007 10:44 pm

I finally finished my ST70 clone yesterday. Yellow_Light_Colorz_PDT_02

It was a major PITA but it got done.

It could not have gotten done without Mike's unselfish help. I literally ran out of words to thank him for all his help.

What was especially cool about the project besides that it is my first tube amp is that i built it with my father. We haven't worked on anything together for a long time and it was beyond cool to get him interested in something like this again. He was building tube amps long before I was born not out of a hobby but more out of a necessity :D

Anyhow here is a pic and I think i'll post a bunch of pics bellow from different build stages.



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Last edited by parabellum on Sat Apr 18, 2009 10:14 pm, edited 1 time in total.
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Postby parabellum » Mon Aug 13, 2007 11:15 pm

Once all the parts got in it was time to start
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Top plate is aluminum. Note my work area ie. my kitchen table with the stool i use for sitting down while tying shoes used for drilling holes through the handle hole.
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Here is the back panel built out of oak board. The plug for the power jack was made by drilling a bunch of tiny holes then cutting it out and filling it till my arms fell off.
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The bottom part made out of plywood. I drilled the holes for let some air in.
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Beer and a puny pumpkin used to put the pressure on the glued construction. Harp bear sucks. Someone brought it to me and its been sitting in my closet for a while now.
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I was painting in front of my door to the horror of my 100 year old neighbors. I hijacked the laundry drying thingy to dry the primer paint.
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I'm guessing neighbors didn't like the square created after I removed the inadequate plastic cover I was using
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Slap some primer on.
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Now that the primer is done time to slap some color on it. Its colonial red, and before you ask me why red let me preemptively answer and say thats the closest I could find to mohagony at home depot.
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After a few coats of colonial red time to let it dry a bit.
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Couldn't find a way to hang the top plate onto the drying contraption so I hung in on the balcony overnight.
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Mount the sockets and the transformer.And start fitting it all together.
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Slap the sides on.
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I thought i was pretty clever when I though of putting the biasing pots together up front and hiding them behind a brass plate for easy access. Had I known how much of a pain in the ass that will turn into I would have scrapped that idea.
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Back side almost complete. Later I put some banana jacks and made them into biasing points.
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Finished box.
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Back view before I put them biasing jacks there as well.
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Now that the wood and metal work is out of the way time to get down to business. Here is a schematic I drew on a single piece of paper so I have a big picture in my head.
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Let the games begin. Pay no attention to the analog meter, My digital one crapped out and I was waiting for the new one in the mail.
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Trying our best to keep it neat but point to point gets busy fast!
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Almost there
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Call the bomb squad I don't know which wire to cut!!!
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After some grief filled day of troubleshooting all the things wrong whose details I wont bother you with. It was ready to be tried out with some input.
I grabbed a very first CD I had near me (turned out it was Johnny Cash) and slapped it into the PS 1 which works only about 10% of the time and hooked up the dynaco A25s. With no preamp or volume control I turned it on and hoped for the best. And then BLAAAAAAAAAAM. Johnny came out at full volume shaking walls. I was jumping up and down like a retard not wanting to shut it off.
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Oh yeah baby. It was a good day!
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Last edited by parabellum on Sat Apr 18, 2009 10:17 pm, edited 1 time in total.
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Postby Shannon Parks » Tue Aug 14, 2007 5:27 am

Very impressive project and documentation! You should be proud. I particularly like the 'bomb squad' pic. Thanks for sharing it with us.
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Postby dhuebert » Tue Aug 14, 2007 7:36 am

What transformers did you use?

Don
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Postby TomMcNally » Tue Aug 14, 2007 8:28 am

Sweet ! Congratulations from another kitchen counter builder.

... tom
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Postby SDS-PAGE » Tue Aug 14, 2007 8:47 am

Very nicely done! It looks like you put a lot of thoughts into it. It's cool that you got to work with your dad too. Hope it will last to be a family heirloom. So, what's your next project? -Min
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Postby parabellum » Tue Aug 14, 2007 9:43 am

@shannon

Thanks. Yeah the bomb squad pic looks scary :o I got many more pics from every possible stage of the build. I figgured someone might find it usefull one day.


@dhubert

Hammond 372JX PT and Hammond 1645 OTs

@Tom

Thanks Tom :)

@Min

Yep, I drew various prototypes before I even got all the parts in one pile. But I learned that this is not a way to go when working with wood. Too much effort and too many unpredictible behaviours.

And yeah I don't plan to get rid of this thing ever. Too much effort to put a price on.

Next project is a preamp designed by Mike, 2A3 SET amp with a new concept for a chassis I thought of. And after that some hopefully kickass looking single driver speakers. Yellow_Light_Colorz_PDT_11
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Postby wiredbecker » Tue Aug 14, 2007 12:46 pm

Dude! That rules!! Big congratulations to you and your dad. Any chance I could convince you to bring it over in a few weeks? We could cycle through my speaker collection or something.
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Postby parabellum » Tue Aug 14, 2007 6:27 pm

Thanks Chris. We'll arrange something after I break the tubes in and finish the preamp. The preamp won't take this long since its infinitely simpler and will just be a utaliterian off the shelf ugly aluminum box.
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Postby Sal Brisindi » Wed Aug 15, 2007 8:05 pm

Awesome job on the amplifier, I hope it sounds as good as it looks!

Regards,
Sal Brisindi
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Postby parabellum » Thu Aug 16, 2007 12:00 pm

Thanks Sal, I hope so too :)
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