simple 6080/6as7 ppp/circlotron project

singh santa · 12th March 2009, 02:03 PM

Hello everybody,
I've made this 6080 ppp15w/channel.DF=16.more wanted for my multi-speaker system.Any suggestion??will post the photo and sch.later.Many thanks! in advance.
Singh

revintage · 12th March 2009, 02:23 PM

So you like Quad-II

?

monyse · 12th March 2009, 03:32 PM

very interesting arrangement ; how do you adjust bias for the 6080 ?

monyse

smoking-amp · 12th March 2009, 05:27 PM

With the 6080 cathodes connected to halfway points of the voltage doublers and the plates connected to the full voltage doubler, there is DC current thru the T? xfmrs (unbalanced load on the voltage doublers). The xfmrs are going to get hot.

Biasing of the 6080's appears to be auto-bias by R11 and R18.

monyse · 12th March 2009, 07:06 PM

I noticed the bias voltage as half of the doubler voltage with the return through R2 and also the supply of the splitter tubes both crossing through the output transformer and tough in opposite direction innbalance can easily occur especially with three 6080 in parallel and this would defy the whole purpose of the circlotron which is not suppose to pass DC through the load This was the reason I asked for the bias adjustement .

monyse

smoking-amp · 12th March 2009, 07:24 PM

With R16 at 100K and R12 at 360K, it looks like auto-biasing by R11 will be around 2/3 control and ground reference thru R2 around 1/3 control (which as you say, goes thru 1/2 the V multiplier.). So line voltage will affect biasing for sure. I could see where some control like this could be useful to keep the 6080's regulated versus line voltage, but this seems like too much effect.

The floating supply connections to R3 and R17 may be intended as bootstrapped (CCS like a'la McIntosh) ) loads for the 6AU6's, but the amount here seems excessive. Probably positive feedback.

singh santa · 13th March 2009, 05:52 AM

Quote:

Originally posted by revintage
So you like Quad-II ?

Hi,it's so called simple.
Rgds!
Singh

singh santa · 13th March 2009, 05:52 AM

Quote:

Originally posted by monyse
very interesting arrangement ; how do you adjust bias for the 6080 ?

monyse

Hi,
I've checked my sch. that I posted. Found that was the one I used at the very beginning.I made some mods and I'm working with the new modified sch. I'll post that modified schematic later.Sorry to all guys.
Regards!
Singh

singh santa · 13th March 2009, 02:28 PM

Pic.6080ppp

singh santa · 13th March 2009, 06:43 PM

Quote:

Originally posted by monyse
very interesting arrangement ; how do you adjust bias for the 6080 ?

monyse

Hello Monyse,
I've added 2 POTs to adjust bias,the attached modified schemtic tells more.
RGDs!
Singh

12th March 2009, 03:32 PM	#3
monyse diyAudio Member Join Date: Dec 2008	circlotron very interesting arrangement ; how do you adjust bias for the 6080 ? monyse

12th March 2009, 05:27 PM	#4
smoking-amp diyAudio Member Join Date: Dec 2001 Location: Hickory, NC	With the 6080 cathodes connected to halfway points of the voltage doublers and the plates connected to the full voltage doubler, there is DC current thru the T? xfmrs (unbalanced load on the voltage doublers). The xfmrs are going to get hot. Biasing of the 6080's appears to be auto-bias by R11 and R18. __________________ Ohms Law V = I R

12th March 2009, 07:06 PM	#5
monyse diyAudio Member Join Date: Dec 2008	circlotron I noticed the bias voltage as half of the doubler voltage with the return through R2 and also the supply of the splitter tubes both crossing through the output transformer and tough in opposite direction innbalance can easily occur especially with three 6080 in parallel and this would defy the whole purpose of the circlotron which is not suppose to pass DC through the load This was the reason I asked for the bias adjustement . monyse

12th March 2009, 07:24 PM	#6
smoking-amp diyAudio Member Join Date: Dec 2001 Location: Hickory, NC	With R16 at 100K and R12 at 360K, it looks like auto-biasing by R11 will be around 2/3 control and ground reference thru R2 around 1/3 control (which as you say, goes thru 1/2 the V multiplier.). So line voltage will affect biasing for sure. I could see where some control like this could be useful to keep the 6080's regulated versus line voltage, but this seems like too much effect. The floating supply connections to R3 and R17 may be intended as bootstrapped (CCS like a'la McIntosh) ) loads for the 6AU6's, but the amount here seems excessive. Probably positive feedback. __________________ Ohms Law V = I R

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12th March 2009, 02:23 PM	#2
revintage diyAudio Member Join Date: May 2007	So you like Quad-II ?

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