Another tube rectified rev D completed, check out the pics!

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Another tube rectified rev D completed, check out the pics!

Postby mark@marktwain » Tue Jan 25, 2005 11:30 am

Hello diy tubers,

Lets Try this again and see if I can get it right this time. Shannon, can you delete the duplicate post under guest?

I just completed my rev D with tube rectification. This is my second tube amp. The first one being the Antique Electronic supply K-502 which is suppling my workshop with tunes. Here's some of the highlights. Dynaco iron with cloth leads from a 1968 SCA-35 doner, RCA 5u4g rectifier tube with dynaco c354 choke, Goldpoint mini-h mono stepped attenuators, walnut "box jointed" case, laminated aluminum and polished copper top and dashboard, bakelite attenuator knobs, teflon hookup wire, silver plated braid sheilding on inputs, all fastners are stainless steel. Sounds excellent and it's dead quiet. I highly recommend this project to all! Hat's off and a cheer to Shannon for the excellent PCB, manual and forum. Hey Shannon hows that ST-70 project going? I'd like to build one of those also. Thanks for hosting the pics Shannon.

Mark

http://www.diytube.com/st35/st35-tubeless.jpg
http://www.diytube.com/st35/st35-top.jpg
http://www.diytube.com/st35/st35-front.jpg
http://www.diytube.com/st35/st35-rear.jpg
http://www.diytube.com/st35/st35-bottom1.jpg
http://www.diytube.com/st35/st35-bottom2.jpg
http://www.diytube.com/st35/st35-pcb.jpg
http://www.diytube.com/st35/st35-goldpoints.jpg
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Re: Another tube rectified rev D completed, check out the pi

Postby Shannon Parks » Tue Jan 25, 2005 12:41 pm

mark@marktwain wrote:Hey Shannon hows that ST-70 project going?


My first ST70 driver board will be waiting for me when I get home tonight. I'm pretty excited about this one. It really is an honor to contribute to the great ST70. Upgrading should be a snap as I will use a wire wrap guide to keep track of the wires, and then use the same numbering scheme - with 'eyelets' even in the same location as the original.

This is not be a total redesign of the ST70 (like others have done) and is happy with the stock bias and power supply circuit. I love the basic ST70 - it just has a wimpy triode phase splitter that isn't up to taming the power tubes for our modern speakers.

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ST-70 driver board?!?!

Postby TerrySmith » Tue Jan 25, 2005 5:59 pm

What type of circuit will it use? LTP phase splitter maybe?
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Re: ST-70 driver board?!?!

Postby Shannon Parks » Tue Jan 25, 2005 6:58 pm

TerrySmith wrote:What type of circuit will it use? LTP phase splitter maybe?


Yep. Here she is:

diytube ST70 driver board

It's a typical modified Mullard design ala Eico and similar to Kevin Kennedy's circuit.

Sorry to hijack your thread, Mark. The pics look great!

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Postby EWBrown » Wed Jan 26, 2005 12:21 pm

Hmmmm, could this possibly be a progenitor of a "next gen" Rev E DIY-35 design?

/ed B in the frozen tundra of NH
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Wow Mark!

Postby tubetwang » Thu Jan 27, 2005 7:18 am

That is on nice amplifier!!

Thanks for the pics.

I'm starting a new tube rectified Rev.D as soon as i get the parts...
Happy tubing...
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Postby veg1515 » Sat Feb 12, 2005 8:43 am

Can someone help me out what extra parts do i need to make a rectified version and what changes to the schematic needs to be made.
thanks mat
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Postby mark@marktwain » Sat Feb 12, 2005 10:26 am

Here's the link to a previous post which I followed. http://www.diytube.com/phpBB2/viewtopic.php?t=366
You need to add a filamant tranny if your using the Dynaco PA-774 power tranny, I used a Hammond 166ms or use a larger hammond power tranny, I believe the 272HX. Replace C9 with a 33uf 450V cap, the Cornell Dubiliers called for in the parts list are not available in a 33uf so I used Panasonics for all four. Replace R34 and R35 with a two terminal connector like is used on the inputs, the PCB is set up for this already. Add a Dynaco C354 choke to the two terminals or just solder the choke wires to the board. Replace D1 and D2 with jumpers, I just used some lead cut offs from resistors. Add the 8-pin octal socket and rectifer tube. I used a 5U4G but you could also use a 5AR4/GZ34 or any flavor of 5U4 but the 5U4g coke bottle shape is super kewel. Here's the links to the schem mods.

http://www.diytube.com/gallery/TubeRectifierPS.pdf

http://www.diytube.com/gallery/LogicalTubeRectifier.pdf

This mod really adds the icing on the cake to this wonderful amp!
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Postby mark@marktwain » Sat Feb 12, 2005 10:48 am

Hey guys besides diy audio one of my other hobbies is woodworking. I would like to offer custom hardwood chassis for your amps and other projects. I can make them to order per your specifications out of any species of wood you desire. I have oak, walnut, popular, birch and cherry on hand but I can get any species you want. I can supply them with mitered corners, box joints like my amp in the pics, blind or through dovetail joints and rounded or chamfered corners. I can also supply you with custom made to order top and bottom plates made out of aluminum, copper or steel. Let me know your needs you can reach me at markgall@marktwain.net
Thanks
Mark
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Thanks for info Mark...

Postby tubetwang » Sat Feb 12, 2005 12:09 pm

right on time...

I was a little puzzled about this rectifier thing...

Louis
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Postby veg1515 » Mon Feb 14, 2005 8:17 am

so i need to get a 33uf 450v cap for c9 and i will be using ned's transformers , so do i need a filament tranny? what part number is that and i still need dynaco part c354 for the choke right? Finally ive got to say mike your signal wire is quite impressive where did u get that? im gonna admit im a little jealous
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Postby mark@marktwain » Mon Feb 14, 2005 9:47 am

Yep, I believe uncle Ned's tranny is a copy of the Dynaco pa-774 so you'll need the extra filament tranny. I used a hammond 166ms from mouser. Uncle Ned has the c354 choke or you can use a hammond from mouser or angela I believe it's a 156r someone correct me if I'm wrong. I constructed the signal wire myself with ebay scores. It consists of 26ga solid core silver plated conductors and a silver plated braided sleeve with heat shrink to seal the ends. I could probably spare some if you interested, shoot me an email with your needs.
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Not all 5AR4s are equal, some are more "equal" tha

Postby EWBrown » Mon Feb 14, 2005 10:11 am

AES sells the JJ 32+32 uF 525V caps, that fit the 1 3/8 inch clamp for reasonable cost, they also have a 50+50 in the same form factor for a little bit more. I use both of these in numerous projects.

5AR4/GZ34s are a bit more tolerant of higher capacitance than most rectifier tubes, but be careful, in that most of the "import" 5AR4s like Sovtek, etc are basically just somewhat upgraded 5Y3s. These are fine for use on a ST35, but it would be ppushing the envelope on an ST-70. The JJ 5AR4s seem to stand up to ST70 service OK, I haven't yet had one fail.

The low cost Chinese made ones (I have some marked "Made in Chian" ) are not even up to 5Y3 capabilities, they will arc over and die on an ST70, and may be risky even for an ST-35.

/ed B in NH
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Postby veg1515 » Mon Feb 14, 2005 11:11 pm

what is AES?
thanks mat
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Postby mark@marktwain » Tue Feb 15, 2005 12:14 am

Antique Electronic Supply
http://www.tubesandmore.com
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