6LU8 Push-pull power amp and other builds

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Re:6P3S Push-pull power amps and others

Postby tony » Fri Sep 09, 2011 11:58 am

Update:

this is a 6P3C push-pull power amp for a friend....6P3C is the Russian equivalent of the 6L6GC tube.....OPT's used Edrel's Z11 cores....

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Last edited by tony on Mon Oct 10, 2011 6:14 pm, edited 1 time in total.
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Re: 6LU8 Push-pull power amp

Postby tony » Fri Sep 23, 2011 2:04 pm

Hi all,

these are 2 OPT's for a push-pull 4D32 tube amp i am building, it has a 1.75in center leg stacked to 3.125inches, using Edrel's Z11(M6) cores.....
finally put to use, to give you an idea, the core is about 15kg at 500 per kilogram and copper at about 2.5kgs at about 700 per kilo......
bobbins used also supplied by Edrel and is nylon type.....
the use of wooden mandrels allowed me to wind the coils in sections, winding one coil after the other to avoid errors and ensure identical traffo build...

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materials used includes:
Kapton tape, polypropylene plastic inter-layer insulation, 1/8 inch masking tapes to provide additional creapage distance:
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one of 4 primary coils and 1 of 4 secondary coils done:
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winding the rest of the coils
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stacking the E and I's to complete the build up:
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Last edited by tony on Sat Sep 24, 2011 8:33 am, edited 1 time in total.
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Re: 6LU8 Push-pull power amp

Postby camotecue » Fri Sep 23, 2011 8:01 pm

nice xformers tony! maybe you can post some frequency measurements when they're done.
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Re: 6LU8 Push-pull power amp

Postby carbondated » Fri Sep 23, 2011 10:00 pm

Good luck! This looks like an interesting project :)
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Re: 6LU8 Push-pull power amp

Postby tony » Sat Sep 24, 2011 8:33 am

camotecue wrote:nice xformers tony! maybe you can post some frequency measurements when they're done.


thanks, looking forward to fabuluos bass with these babies..... :D
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Re: 6LU8 Push-pull power amp

Postby tony » Sat Sep 24, 2011 8:35 am

carbondated wrote:Good luck! This looks like an interesting project :)


thanks, this has been cooking up im my head for more than 3 years now eversince Gerry StaMaria gave me a couple of those tubes.... :D
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Re: 6LU8 Push-pull power amp

Postby edrel sison » Sat Sep 24, 2011 12:31 pm

tony wrote:a couple of those tubes.... :D


i wonder how high the B+ would be. what are those tubes tony? :)
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Re: 6LU8 Push-pull power amp

Postby tony » Sat Sep 24, 2011 12:55 pm

edrel sison wrote:
tony wrote:a couple of those tubes.... :D


i wonder how high the B+ would be. what are those tubes tony? :)


4D32 tubes, i am building a push-pull amp 120wpc...B+ at 650volts.....the OPT will be conservatively used, it can do higher than 120watts...
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Re: 6LU8 Push-pull power amp

Postby tony » Wed Oct 05, 2011 6:36 am

this is a 16 KT88 push-pull power amp i am building, the parts were recycled from an old amp and was given a new chassis, 2 x 3mm aluminum plates, 14inches x 17 inches powder coated. expected to complete this coming weekend.

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power supply section:
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Re: 6LU8 Push-pull power amp

Postby carbondated » Wed Oct 05, 2011 9:54 am

Wow. That should come with a spit roaster so that you can make lechon manok on top of it. :D Amazing! Post pics when you finish!
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Re:kt88 Push-pull power amp

Postby tony » Mon Oct 10, 2011 5:34 pm

finally.....

input tube is a 12BY7, ltp drivers are paralleled 12BH7's, this is a non-global negative feedback amplifier, the KT88's are run as triodes so that the resulting low plate resistance from parallel operation negates the need for global negative feedback.....

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biasing at -47v power consumption was:
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backing down a bit to -50volts yeilded this power consumption and seemed to be stable, no drifting was noticed and the tubes were surprisingly within 2mA of each other....
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setup psu and amplifier block combo for a listening test:
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Re: 6LU8 Push-pull power amp

Postby trod93 » Mon Oct 17, 2011 8:12 pm

I heard these were tested on a 5 way speaker system and sounded awesome. Lots of power.

Congrats!
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Re: 6LU8 Push-pull power amp

Postby tony » Tue Oct 18, 2011 6:56 pm

thanks tukayo.... i was also informed by the owner about it..... :D
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Re: 6LU8 Push-pull power amp

Postby tony » Sun Oct 23, 2011 6:26 pm

update,
2 sets now on-going construction, jopet sold me some tubes for cheap........one is an EL34 push-pull based on a Mullard/HK Citation design, the other is a push-pull 829b power amps....

EL34 chassis:

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829b chassis:
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drilling:
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transformers for the 2 projects on going-finishing:

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Re: 6LU8 Push-pull power amp

Postby amigo » Sun Oct 23, 2011 10:30 pm

tony, sir galing... 8) :clap: :rock:
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Re: Re:kt88 Push-pull power amp

Postby lovejbl » Thu Nov 10, 2011 3:04 pm

tony wrote:finally.....

input tube is a 12BY7, ltp drivers are paralleled 12BH7's, this is a non-global negative feedback amplifier, the KT88's are run as triodes so that the resulting low plate resistance from parallel operation negates the need for global negative feedback.....

Image
Image
Image
Image
Image
Image

biasing at -47v power consumption was:
Image

backing down a bit to -50volts yeilded this power consumption and seemed to be stable, no drifting was noticed and the tubes were surprisingly within 2mA of each other....
Image

setup psu and amplifier block combo for a listening test:
Image
Image
Image


It was built to help multi-amplification system by running the JBL 2235s for as low as 20hz, stricly subwoofer use only. The test was superb from a JBL 2245s. The tubes were warm but never over-heated. This outperforms my friend's Audio Research mass candle lights according to him; I applauld to the mastermind builder Tony!!! thank you so much.
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Re: Re:6P3S Push-pull power amps and others

Postby marbinism » Thu Nov 10, 2011 5:45 pm

tony wrote:Update:

this is a 6P3C push-pull power amp for a friend....6P3C is the Russian equivalent of the 6L6GC tube.....OPT's used Edrel's Z11 cores....

Image
Image
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NICE one sir tony.
+++100...
:D :D :D
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Re: 6LU8 Push-pull power amp

Postby tony » Fri Nov 11, 2011 7:58 am

It was built to help multi-amplification system by running the JBL 2235s for as low as 20hz, stricly subwoofer use only. The test was superb from a JBL 2245s. The tubes were warm but never over-heated. This outperforms my friend's Audio Research mass candle lights according to him; I applauld to the mastermind builder Tony!!! thank you so much.

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to be honest, i had my doubts in the beginning.....but as Lin Gomez would have it, "never say never"........

Mr. R.V. of Malabon did a supperb job with the first build, even the power transformer was made of GOSS iron, as such i found it hard to have it rewinded, i opted to commission Mr. Rey Luis instead to make another power traffo to supply the filaments wired in series for 24 volts, and the preamp tubes wired 12 volts...

Mr. Tony Rodriguez made the wooden plinth which the amps plates, 3mm thick rested on....

the output traffo was made out out pin stripped 0.35mm GOSS core, really vintage, i decided to get a closer look, and after testing i found out that connecting the 8 ohm speaker to the 16ohm tap reflected an impedance of about 1600 ohms at the primary, pretty close load to the very low plate resistance of the paralleled KT88', lesser ohms would have meant greater power, but i opted for SQ rather than wattage....armed with this knowledge, the amp was a GO......

the original amp used the 6AN8 preamp driver with the triode section in a concertina configuration, i felt this to be too wimpy to push those KT88 grids with gusto......

and so the decision to use the 12BY7.12BH7 combo, gain is ample but not too high so as to require global negative feedback......the high tranconductance of the 12by7 ensures low distortion and the paralleled plates of the 12bh7's ensures low impedance drive to the kt88 grids....
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Re: 6LU8 Push-pull power amp

Postby tony » Sun Dec 04, 2011 11:59 am

my new build: EL34/6CA7 finals driven by 6N1P/6J9 preamp tubes, other options for drivers are 6CG7/6GU7. 6JG5.....

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underneath:

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biasing boards:
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zener diode stack:
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Re: 6LU8 Push-pull power amp

Postby harvey_a_vasquez » Sun Dec 04, 2011 6:31 pm

^^^
Nakakabilib!
I wish I can also get into this when I get home.
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