Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

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

Looking for circuit tips for 2 matched pairs of 6C33C-B (6S33S-V)
Looking for circuit tips for 2 matched pairs of 6C33C-B (6S33S-V)
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 31st July 2019, 09:15 AM   #1
Vortex is offline Vortex  Hungary
diyAudio Member
 
Vortex's Avatar
 
Join Date: Jan 2004
Location: Budapest, Hungary, Europe
Send a message via ICQ to Vortex Looking for circuit tips for 2 matched pairs of 6C33C-B (6S33S-V)
Default Looking for circuit tips for 2 matched pairs of 6C33C-B (6S33S-V)

Deall forum members,

after having finished my little Class-D project for the kitchen's "hifi" - I'd like to move to a new project.

I have 2 matched pairs of Ulyanov 6C33C-B (6S33S-V) tubes, so 4 tubes alltogether. I got them from my father, he's a big EL34/KT88 builder but these are some different animals and I thought I give it a try here and ask if there're ANY special considerations we need to take into account when building a stereo amp with these. I would like to make him a stereo integrated amp for Xmas 2019, a good one.

Tubes are new. If they're matched pairs REALLY - who knows, anyone can state anything on the internet, right ? Anyway, the stamps on the glasses are matching. They're here and I'd like to get some really great triode sound out of them.

I read some issues regarding these tubes about reliability, or at least - put it that way - the quality spread seems to be big. What's the truth behind that, shall we be worried ? These tubes are easy to get cheap here from the neighbouring country, Ukraine, nevertheless I'd like to employ some basic protections in the circuit, either in the design itself or using a small microcomputer (like an Arduino) to monitor current, voltages, power-on hours and setting/modifying bias automatically, or even turn-off the amp via relays if that's the case. Maybe you have some basic hints what we need to take into account with these tubes .. ?



Design considerations for now:
- we read the article with Tim Mellow's OTL design but we think we might stick to a good old classic design with OT which doesn't stress the tubes at all.

- I'd like to have a good, reliable, great sounding Class AB, 2 tubes per side in pushpull, toroidal OT (from Transformatory toroidalne - Producent transformatorow Toroidy.pl) calculated into 6+ Ohms (8 in reality but most 8 ohm drivers go reasonably below 8 Ohms in reality so we design the OT to 6 Ohms then and using the amp with nominal 8 Ohm speakers) and then it should be fine. XLR inputs, fully balanced design with good common mode noise rejection - that's all I have in mind right now.


My question rather focuses on reliability, stability and longevity but if somebody has an already-finished good schematics, go ahead..
__________________
IT guy with a broad taste of music: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16
  Reply With Quote
Old 31st July 2019, 04:51 PM   #2
AVWERK is offline AVWERK  United States
diyAudio Member
 
AVWERK's Avatar
 
Join Date: Jan 2004
Location: So Calif.
301F1604-D08E-497C-8912-192829D9874E.jpeg

As suggested by Atmasphere , run new tubes for in 4 days straight
This was my setup gig

In the “New Tim Mellows OTL project” post #751

Regards
David
  Reply With Quote
Old 31st July 2019, 09:22 PM   #3
FullRangeMan is offline FullRangeMan  Brazil
diyAudio Member
 
FullRangeMan's Avatar
 
Join Date: Aug 2009
Location: Brazil
Never heard about a matched pair of 6C33 due the parameters variations and use of two cathodes.
__________________
>Never go to a psychiatrist, adopt a cat or dog from the streets. On the streets pets live only two years average.
  Reply With Quote
Old 31st July 2019, 11:40 PM   #4
TonyTecson is offline TonyTecson  Philippines
diyAudio Moderator
 
TonyTecson's Avatar
 
Join Date: May 2003
Location: Maybunga, Pasig City
Looking for circuit tips for 2 matched pairs of 6C33C-B (6S33S-V)
this tube was meant for use as series pass regulator much the same way as the 6336 and the 6080, even within the same envelope, matching is very hard...

who would imagine the hifi crowd will use them for audio amplifiers?
__________________
planet10 needs your help: Let's help Ruth and Dave...http://www.diyaudio.com/forums/plane...ml#post5010547[B
  Reply With Quote
Old 1st August 2019, 07:17 AM   #5
6A3sUMMER is offline 6A3sUMMER  United States
diyAudio Member
 
Join Date: Jun 2016
Individual Self Bias Cathode Resistors (with appropriate individual bypass capacitors)
does several things:

(with proper design and calculations)
Advantage: Allows the circuit to come up gracefully at the very first power up (no multiple bias adjustments to do quickly at first power up that fixed adjustable bias requires).
Advantage: Individual self bias does not require a regulated B+.
(Disadvantage for fixed adjustable bias circuits: they require regulated B+ unless you want to do multiple back and forth Re-adjustments of the bias).
Advantage: Allows you to easily see the match of cathode currents.
Advantage: Tends to reduce the chance of thermal run-away.
Advantage: Allows you to easily check the drift and aging of the individual cathode currents over time.

Are there disadvantages to individual self bias, yes. But all the above advantages always apply.

"All Generalizations Have Exceptions" - Me

Last edited by 6A3sUMMER; 1st August 2019 at 07:35 AM.
  Reply With Quote
Old 2nd August 2019, 02:02 AM   #6
gabdx is offline gabdx  Canada
diyAudio Member
 
Join Date: Jan 2008
I gathered new recent experience with real toroidal output transformers and also EI cores, standard transformers.

There is one major problem, in push-pull , any small magnetization reduces the INDUCTANCE of the push-pull, there is a small within -/+ 0.5ma bias where it has a very good bass response and BEAUTIFUL sound, and you can only set this up with a high definition 192khz analyser....

So, cathode bias doesn't guarantee a 0 net magnetization, some adverse current could still flow or the transformer sections would not be equal by 0.5 ohm which the cathode or AUTOMATIC bias would not detect!!!!!!!!

The EI cores are surprisingly nearly as bad as toroids or as quad C cores etc.

This is VERY important with the 6c33c with drifting bias and a long warm up time.

BTW I designed a driver and input stage for this tube which doesn't require any feedback..

The major reason I didn't build it is that there was no suitable SET transformer... and the power supply passive with at least 1mf (high currents0 was very costly. If you run this tube with anything below 1mf there is a compromise, maybe I am exaggerating, but I calculated it at the time... it needs a substantial chokes and capacitor bank, the pre-sections need a dedicated transformer to separate from the high current demand of the output tubes.
__________________
amplificateurslegrand.ca
  Reply With Quote
Old 2nd August 2019, 03:36 AM   #7
TonyTecson is offline TonyTecson  Philippines
diyAudio Moderator
 
TonyTecson's Avatar
 
Join Date: May 2003
Location: Maybunga, Pasig City
Looking for circuit tips for 2 matched pairs of 6C33C-B (6S33S-V)
OPT's for low internal resistance tubes like these are so easy to make, even isolation type step down power traffos can be used and still get good results, but you have to re orient the E's and the I's...
__________________
planet10 needs your help: Let's help Ruth and Dave...http://www.diyaudio.com/forums/plane...ml#post5010547[B
  Reply With Quote
Old 2nd August 2019, 06:12 PM   #8
gabdx is offline gabdx  Canada
diyAudio Member
 
Join Date: Jan 2008
I would use auto bias with pre set bias to maximize inductance, in other words, adjust the settings manually at which the bias is auto-set, not trusting its sensing balance.
__________________
amplificateurslegrand.ca
  Reply With Quote
Old 2nd August 2019, 06:33 PM   #9
cnpope is offline cnpope  United States
diyAudio Member
 
Join Date: Aug 2009
Location: College Station, TX
Quote:
Originally Posted by Vortex View Post
Deall forum members,

after having finished my little Class-D project for the kitchen's "hifi" - I'd like to move to a new project.

I have 2 matched pairs of Ulyanov 6C33C-B (6S33S-V) tubes, so 4 tubes alltogether. I got them from my father, he's a big EL34/KT88 builder but these are some different animals and I thought I give it a try here and ask if there're ANY special considerations we need to take into account when building a stereo amp with these. I would like to make him a stereo integrated amp for Xmas 2019, a good one.
Would you be willing to consider an output transformerless design? There are several schematics out there using a pair of 6C33C tubes to get about 25W into 8 ohms. I've been running these OTLs for a few years now, with no problems at all.
  Reply With Quote
Old 2nd August 2019, 07:13 PM   #10
kodabmx is offline kodabmx  Canada
Spreading triode love.
diyAudio Member
 
Join Date: Oct 2011
Location: Toronto
Looking for circuit tips for 2 matched pairs of 6C33C-B (6S33S-V)
Or use an autobias board from Pavel. audioamp.eu
  Reply With Quote

Reply


Looking for circuit tips for 2 matched pairs of 6C33C-B (6S33S-V)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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
6S33S-V / 6C33C-B AUDIOPHILE POWER TRIODE + IN-18 nixie SALE gioss Swap Meet 2 24th October 2015 08:29 PM
WTB: 2 matched pairs 2SJ313 and 2 matched pairs 2SK2013 nr12 Swap Meet 0 20th January 2015 04:54 AM
Thermography on 6C33C/6C18C aka. 6S33S/6S18S doctormord Tubes / Valves 7 11th March 2013 12:22 PM
FS: NOS 6S33S/6C33C Russian Triode Tubes Kuka Swap Meet 3 7th November 2011 09:38 AM
Can the 6S33S/6C33C be mounted horizontally? ben_f_m Tubes / Valves 7 10th August 2010 06:16 PM


New To Site? Need Help?

All times are GMT. The time now is 01:56 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Copyright ©1999-2019 diyAudio
Wiki