Go Back   Home > Forums > Amplifiers > Tubes / Valves

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 15th July 2012, 09:34 AM   #1
AJT is offline AJT  Philippines
diyAudio Moderator
 
AJT's Avatar
 
Join Date: May 2003
Location: Palatiw, Pasig City
Default My Russian SET

Hi, now it can be told.... ;D

the inspiration for building this amp came from this page: 6C33C-B SE Verstaerker von Juergen Buschmann

as i am one who is not a true copycat in the strictest sense, i made some deviations from the original design, first, i will use fixed biasing, fuses are installed to limit current should the 6C33 tubes decide to run-away, i am confident it will not happen, i did a prior burnin-in of the tubes as per recommendations of the fellows at diy-audio....second is the use of diodes for biasing the cathodes of the 6P15P voltage amp tube, my experience with Broskie's CCDA preamps using diode biasing has been very encouraging that i only use resistor/capacitor cathode bias combo in my guitar amps exclusively....and i am not turning back on that....


so, this is to document construction of the Russian 6C33C SET amp.

It starts with building a set of power traffos and common mode chokes and a pair of OPT's or output transformers capable of about 10watts into 8ohm loads....
i chose a core with center leg of 1.5 inches stacked to 2 inches, the traffo is butt joint with a suitable gapping material of about 0.5mm. the mass of the traffo core was chosen so that core saturation at low frequencies are mitigated. Turns ratio of the OPT is 10, with an rp of 150 ohms, our plate load needs to be 300ohms for maximum power output, but since i am not after maximum power output, i opted for a 600:6ohm OPT, so that with an 8 ohm speaker, the reflected load is 800ohms, very easy for the 6C33 plate, a 4ohm speaker otoh reflects a 400 ohms load to the plate of the 6C33 so that is still greater than 300ohms...

Aanyway real speakers are not constant 8ohms no matter how the manufacter tell us it is so...so it is easy for you to guess why the choice of the 6C33, simply put, design and building of output traffo is easy, the low rp of the 6C33 does not require a high inductance primary, leakage is no problem, inter-leaving is easy, you can opt not to have it...... it's an easy choice if you ask me.....

.....

SET tube amps demand a lot of power for a measly power output, here i am making a power traffo of with a core rating of about about 390watts,if you ask me, i wished this traffo could have been bigger, it will supply a continuos power of a little over 220 watts regardless of whether the amp is playing music or not.....if we were building a classAB amp instead, we could be idling at less than this.

Click the image to open in full size.

for the power traffo, i used a bobbin for 1.5 inch and 2 3/8 inch stack:

Click the image to open in full size.
Click the image to open in full size.
Click the image to open in full size.
Click the image to open in full size.
Click the image to open in full size.
Click the image to open in full size.
Click the image to open in full size.


filament winding terminations:
Click the image to open in full size.
Click the image to open in full size.

built-up traffo:
Click the image to open in full size.
Click the image to open in full size.

bamboo pegs at the 4 mounting holes, this lets the varnish go in between laminates.
here the traffo is hung out to dry for a day or so....
Click the image to open in full size.
Click the image to open in full size.



these are the output traffos, core is 1.5 x 2 inches, impedance ratio is 600:6 ohms, so that turns ratio is 10..........

building a pair side by side, one section by one section at a time until the whole buld is completed, ensured that the pair built are identical......

Click the image to open in full size.
Click the image to open in full size.
Click the image to open in full size.

dipping in varnish:
Click the image to open in full size.

hung out to dry under the sun after dipping in varnish....
Click the image to open in full size.
Click the image to open in full size.

temporary brackets installed on the 2 opts to keep the E's and I's together since they are butt joint with a gapping paper sandwiched in between them...
Click the image to open in full size.
Click the image to open in full size.

with endbells installed after painting:
Click the image to open in full size.
Click the image to open in full size.
  Reply With Quote
Old 15th July 2012, 09:37 AM   #2
AJT is offline AJT  Philippines
diyAudio Moderator
 
AJT's Avatar
 
Join Date: May 2003
Location: Palatiw, Pasig City
2nd installment: chassis preparation;

aluminum gage 14 was used, 0.075inch thick for both box and bottom plate, wooden sidings used to cover the sides...aluminum is very easy to work with, a joy to drill and quick to file out and polish....i used a half round file to make straight cut-outs....

after drilling and punching holes, ready for powder coating......

Click the image to open in full size.
Click the image to open in full size.
Click the image to open in full size.

bottom plate:
Click the image to open in full size.

after powder coating.....
Click the image to open in full size.
Click the image to open in full size.
Click the image to open in full size.
  Reply With Quote
Old 15th July 2012, 10:51 AM   #3
AJT is offline AJT  Philippines
diyAudio Moderator
 
AJT's Avatar
 
Join Date: May 2003
Location: Palatiw, Pasig City
3rd installment: mounting of traffos, filter caps and sockets......

Click the image to open in full size.
Click the image to open in full size.
Click the image to open in full size.
Click the image to open in full size.
Click the image to open in full size.
Click the image to open in full size.
Click the image to open in full size.

stainless steel allen key type bolts used, guaranteed rust free for the life of the amp....
Click the image to open in full size.
Click the image to open in full size.
Click the image to open in full size.
Click the image to open in full size.
Click the image to open in full size.
Click the image to open in full size.
Click the image to open in full size.

tubes fitted...
Click the image to open in full size.
  Reply With Quote
Old 15th July 2012, 11:35 AM   #4
Account disabled at member's request
 
Join Date: Jul 2009
excellent work, impressive build quality!

I believe he 6c33c is a beautiful tube. i plan on using it to drive a gu81m based set amp (still have two big bottles left)

http://www.moehrenbude.de/Moehre/ima...33C_simpel.pdf

output transformer is tricky...260mA 5k primary. Still haven't found an exact match in commercially available (and affordable) products.

anyways...great work and I like the white bells!
  Reply With Quote
Old 15th July 2012, 12:17 PM   #5
AJT is offline AJT  Philippines
diyAudio Moderator
 
AJT's Avatar
 
Join Date: May 2003
Location: Palatiw, Pasig City
Quote:
Originally Posted by Alexontherocks View Post
excellent work, impressive build quality!

I believe he 6c33c is a beautiful tube. i plan on using it to drive a gu81m based set amp (still have two big bottles left)

http://www.moehrenbude.de/Moehre/ima...33C_simpel.pdf

output transformer is tricky...260mA 5k primary. Still haven't found an exact match in commercially available (and affordable) products.

anyways...great work and I like the white bells!

thanks Alex, i built all the irons in this amp......there are no commercially available traffos that i know of......

indeed the 6C33 is a beautiful tube.....
  Reply With Quote
Old 15th July 2012, 12:22 PM   #6
AJT is offline AJT  Philippines
diyAudio Moderator
 
AJT's Avatar
 
Join Date: May 2003
Location: Palatiw, Pasig City
wiring completion;

at the start......
Click the image to open in full size.

bias and high voltage dc psu board installed......
Click the image to open in full size.

high current main B+ rectifier installed in pcb at the left, the 2 filter caps are for the 400volt dc supply to the 6P15P voltage amplifier stage....
Click the image to open in full size.
Click the image to open in full size.
Click the image to open in full size.

central grounding bus installed.....
Click the image to open in full size.
Click the image to open in full size.


front-end wiring complete....
Click the image to open in full size.

input tube 6P15P cathode bias uses diode string in a pcb.....
Click the image to open in full size.
Click the image to open in full size.

6C33 grid bias pots installed....
Click the image to open in full size.
Click the image to open in full size.


almost there......
Click the image to open in full size.

i wanted a time delay for the 6C33plates to give enough time for the filaments to get warmed up prior to application of B+ so i designed and built a 3 minute delay timer with a soft starting resistor of 12k/5watts in series with main B+ ac supply to the bridge rectifier....there is a 2 color panel led that blinks red about once each second and turns green at the end of the timing period...the 12k resistor is shorted out at this time.....

Click the image to open in full size.
Click the image to open in full size.

underside of the amp completed.....
Click the image to open in full size.


the bottom plate is fitted with 2 x 12volt ball bearing fans, so mitigate potential noise, these fans are powered by 6 volt dc supplies, they move air to go past the 6C33 sockets to somehow cool them down....
Click the image to open in full size.
  Reply With Quote
Old 15th July 2012, 12:24 PM   #7
rajucc is offline rajucc  India
diyAudio Member
 
Join Date: Aug 2011
Location: Kolkata
Great Work
  Reply With Quote
Old 15th July 2012, 01:44 PM   #8
Account disabled at member's request
 
Join Date: Jul 2009
Wel done Sir!

You must be proud. Completing a project without commercially available products is real DIY.

Could you please take some measurements when you are finished?

Best
  Reply With Quote
Old 15th July 2012, 02:09 PM   #9
MelB is offline MelB  Canada
diyAudio Member
 
Join Date: Feb 2005
Location: BC Canada
Bravo. Most excellent work. Love the pics on the transformer winding. In fact, I love all the pictures! Thanks for sharing.
  Reply With Quote
Old 15th July 2012, 02:21 PM   #10
AVWERK is offline AVWERK  United States
diyAudio Member
 
Join Date: Jan 2004
Location: OC,Calif.
2 big thumbs up!
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
High end Ortho Amp on a basic Russian Tube DHT SET DIY design regal Headphone Systems 2 7th December 2012 11:46 AM
NOS Capacitors(russian, phillips), Russian tubes, SS amp kits, power TX rvrazvan Vendor's Bazaar 0 26th May 2011 04:32 PM
WTT: One set of F4 boards for one set of F3 boards KT Swap Meet 0 16th May 2008 03:49 PM
Iron set for Paraglow (2A3) SET amplifier Alain Favret Swap Meet 1 19th March 2004 06:23 AM


New To Site? Need Help?

All times are GMT. The time now is 01:41 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2