6LU8 Push-pull power amp and other builds

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Re: 6LU8 Push-pull power amp and other builds

Postby tony » Sun Mar 11, 2012 3:22 pm

bass_nut wrote:
tony wrote:
Thanks Doc Fer,

will you be interested is say a qaud GU50 pp amp for 200 watts? or a pair of GM70 push-pull for the same power? these Russian Tubes are the bang-for the buck tubes, especially the GU-50....

i also have a quad of QE08-200 which can make 300watts, but sadly, these tubes are very rare and expensive...


type na type natin iyan 200wpc p/p with inexpensive and readily available tubes, kuya Tony :clap: :clap:



this will be a 3pc set with one psu block and 2 channel blocks, you can ask your kababayan, Larry to make the plinths....will start the design process soon... 8)
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Re: 6LU8 Push-pull power amp and other builds

Postby bass_nut » Sun Mar 11, 2012 6:14 pm

3 piece is very good idea and implementation.. hindi gaanong mabigat kaya madaling i-position. distributed din po yung heat generation. thanks, kuya Tony ;)
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Re: 6LU8 Push-pull power amp and other builds

Postby s2kov » Sun Mar 11, 2012 6:53 pm

taga north din ba yung owner nun giant amp na gumamit ng 16 x KT88?? :rofl: :rofl:
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Re: 6LU8 Push-pull power amp and other builds

Postby vintage_dog » Sun Mar 11, 2012 7:47 pm

congrats tony and thanks for sharing your projects and your passion. :clap:

would it be possible to borrow so i can listen to one of your amps? the 6LU8 PP seems like a nice one.
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Re: 6LU8 Push-pull power amp and other builds

Postby tony » Sun Mar 11, 2012 7:49 pm

s2kov wrote:taga north din ba yung owner nun giant amp na gumamit ng 16 x KT88?? :rofl: :rofl:


nasa USA na yung amp na yan....
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Re: 6LU8 Push-pull power amp and other builds

Postby tony » Sun Mar 11, 2012 7:51 pm

vintage_dog wrote:congrats tony and thanks for sharing your projects and your passion. :clap:

would it be possible to borrow so i can listen to one of your amps? the 6LU8 PP seems like a nice one.


yes, gladly, tatapusin ko lang yung bottom cover.....
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Re: 6LU8 Push-pull power amp and other builds

Postby vintage_dog » Sun Mar 11, 2012 8:18 pm

tony wrote:
vintage_dog wrote:congrats tony and thanks for sharing your projects and your passion. :clap:

would it be possible to borrow so i can listen to one of your amps? the 6LU8 PP seems like a nice one.


yes, gladly, tatapusin ko lang yung bottom cover.....


sige. thanks :)
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Re: 6LU8 Push-pull power amp and other builds

Postby s2kov » Sun Mar 11, 2012 10:09 pm

USA?! :o heavy-gat yan! ;)

tony wrote:
s2kov wrote:taga north din ba yung owner nun giant amp na gumamit ng 16 x KT88?? :rofl: :rofl:


nasa USA na yung amp na yan....
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Re: 6LU8 Push-pull power amp and other builds

Postby tony » Sun May 13, 2012 11:16 am

vintage_dog wrote:congrats tony and thanks for sharing your projects and your passion. :clap:

would it be possible to borrow so i can listen to one of your amps? the 6LU8 PP seems like a nice one.



an oldtimer, came to the house 3x and asked to audition the unit....he bought the amp as it was..... :D

but i have been commissioned to make another two, this time you will get a chance to listen to it, i will bring it to the competition when it happens...

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Re: 6LU8 Push-pull power amp and other builds

Postby tony » Tue May 15, 2012 8:03 pm

after over a year in hibernation, i am continuing the build of this TV tube power amp:
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211 Push-pull power amp

Postby tony » Thu May 17, 2012 5:48 am

i had an AMX 211 pp amp set brought to the house, the preamp traffo burned out, and there was mechanical buzzing in one channel....

the amp is rated 150watts per channel.....211 output tubes were driven by a pair of EL34 drivers IT coupled to the 211 grids....
power was awesome....

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this is the replacement traffo for the preamp, it is bigger and used bigger gauge wires with an electrostatic shield incorporated to the traffo to reduce line noise...
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power consumption:
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Re: Russian SET amp

Postby tony » Sun Jul 15, 2012 6:52 pm

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

the inspiration for building this amp came from this page: http://www.jogis-roehrenbude.de/Leserbr ... /6C33C.htm

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.

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

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filament winding terminations:
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built-up traffo:
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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....
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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......

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dipping in varnish:
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hung out to dry under the sun after dipping in varnish....
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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...
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with endbells installed after painting:
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Re: Russian SET amp

Postby tony » Sun Jul 15, 2012 6:54 pm

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....:D

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

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bottom plate:
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after powder coating.....
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mounting of traffos, filter caps and sockets......

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stainless steel allen key type bolts used, guaranteed rust free for the life of the amp....
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tubes fitted...
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Last edited by tony on Sun Jul 15, 2012 8:14 pm, edited 1 time in total.
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Re: Russian SET amp

Postby tony » Sun Jul 15, 2012 8:14 pm

wiring completion;

at the start......
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bias and high voltage dc psu board installed......
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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....
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central grounding bus installed.....
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front-end wiring complete....
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input tube 6P15P cathode bias uses diode string in a pcb.....
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6C33 grid bias pots installed....
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almost there......
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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.....

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underside of the amp completed.....
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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....
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QE08/200 push-pull amp.monoblocks.

Postby tony » Sun Sep 23, 2012 9:27 am

QE08/200 push-pull amp.monoblocks.

i have always wanted to build an 813 push-pull power amp, but the B+ of 1500vdc is way too high for me...
then at about 2008, Gerry Sta. Maria(400-2762), my regular tube pimp, gave me a quad of of these tubes.....QE-08/200 tubes made by Philips...Image...Image.....datasheet here: http://www.rell.com/filebase/en/src/Dat ... 08_200.pdf
the tube has 3 cathodes in parallel so that at 6.3volts, filament draw is 3.9A, now this is about the same as a quad 6L6GC tubes....

picture of the tube side by side with the more popular KT88 and EL34...i know of no other tube bigger than this one that can deliver big powers at sub 1kv voltage levels.....this tube made by Philips is diy'er friendly...

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````````````````````````````````````````````
Design Steps:

1. Choose QE08/200 operating point for push-pull class AB2....

B+ = 750vdc
G2 = 250vdc
Vg1 = -45volts
Ipmax = 2 x 280mA
Ig2max = 2 x 40mA
Ig1max = 2 1mA
Vg1pk-pk = 110volts
anode load of 3500ohms plate to plate

2. Design of power traffo:
2.1 total power input to tubes = [(2 x 210)+(2 x 10)]watts = 440watts
2.2 required filament power for output tubes = 4 x 3.9A x 6.3vac = 98watts
2.3 required filament power for preamp/driver tubes = 6.3vac x 3A = 18.9 watts
2.4 power required by preamp/driver tubes = 20 watts (estimated)
2.5 total power required from power traffo secondary = 440 + 98 + 18.9 + 20 = 576 watts
2.6 required power traffo VA rating = 576watts/0.6 = 961 volt-amperes
2.7 as per RDH4, required power traffo must at least have a core area A(in square inches) equal to Sqrt(VA)/5.58, so A = [sqrt961]/5.58, or 5.56 square inches...there are many core sizes that can satisfy this requirement, i choose a core with 2 inch center leg, stacking to about 3.5 inches.
2.8 now that we have a core, we can now determine the required voltages...
2.9 Datasheet specifies a B+ of 750vdc means that that is the B+ at full power, so that we have to design for higher standby voltage, i select 75volts higher so that out B+ will idle at 825vdc....it is normal for a tube psu to sag big under load...
2.10 Votage doubler will be employed, so that the secondary ac required becomes 825vdc/2.8 = 294 volts...required current rating of this winding = 440/750 = 0.59A, using a #19 wire allows 1.8A at 700cm/ampere, way more than what is requried...
2.11 fixed biasing will be used and a bias or -45 volts will need a dc of more than 100volts or say 150volts, again this will be a voltage doubler type to enable the use of mosfet source followers to directly drive the grids of the QE08/200, required ac winding is 150/1.4 = 107volts ac, #24 wire is to be used here..
2.12 for the preamp and driver tubes, a separate 450volt dc supply will be required, ac winding is 450/1.4 = 325vac, #29 wire is to be used here...
2.13 we will calculate primary winding at 230volts ac, primary turns = 1750/6 = 290 turns, we will use #17 wire, turns per volt, t/v then equals 290/230 = 1.27turns per volt....
2.14 now we look at the filament windings, because of the huge filament currents, i decided to series connect the power tube's filaments, so that 12.8 volts is required, 16 turns #15 x 2 strands....
2.15 coil table summary:
primary......290turns of #17 magnet wire
secondary 1.......373 turns of #19 magnet wire
secondary 2.......135 turns of #24 magnet wire
secondary 3.......412 turns of #29 magnet wire
filament1..........16 turns of 2 x #15 magnet wire
filament2..........8 turns of 2 x #18 magnet wire
2.16 Estimated copper weight at 2kg and core steel weight at 10kg, wright of built up traffo without covers is about 12kgs...this more or less completes our transformer design, actual number of turns tend to change during actual build, this is quite normal...
Last edited by tony on Thu Oct 18, 2012 8:01 am, edited 1 time in total.
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Re: 6LU8 Push-pull power amp and other builds

Postby hypertriode » Sun Sep 23, 2012 9:36 am

Very nice Tony!!! :clap:
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6LU8 Push-pull power amp and other builds

Postby s2kov » Sun Sep 23, 2012 10:20 am

True designer! :)
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Re: QE08/200 push-pull amp.monoblocks.

Postby AbadSantos 7 » Sun Sep 23, 2012 1:17 pm

tony wrote:QE08/200 push-pull amp.monoblocks.

i have always wanted to build an 813 push-pull power amp, but the B+ of 1500vdc is way too high for me...
then at about 2008, Gerry Sta. Maria(400-2762), my regular tube pimp, gave me a quad of of these tubes.....QE-08/200 tubes made by Philips....http://www.rell.com/filebase/en/src/Dat ... 08_200.pdf
the tube has 3 cathodes in parallel so that at 6.3volts, filament draw is 3.9A, now this is about the same as a quad 6L6GC tubes....

picture of the tube side by side with the more popular KT88 and EL34...i know of no other tube bigger than this one that can deliver big powers at sub 1kv voltage levels.....this tube made by Philips is diy'er friendly...

Image

````````````````````````````````````````````
Design Steps:

1. Choose QE08/200 operating point for push-pull class AB2....

B+ = 750vdc
G2 = 250vdc
Vg1 = -45volts
Ipmax = 2 x 280mA
Ig2max = 2 x 40mA
Ig1max = 2 1mA
Vg1pk-pk = 110volts
anode load of 3500ohms plate to plate

2. Design of power traffo:
2.1 total power input to tubes = [(2 x 210)+(2 x 10)]watts = 440watts
2.2 required filament power for output tubes = 4 x 3.9A x 6.3vac = 98watts
2.3 required filament power for preamp/driver tubes = 6.3vac x 3A = 18.9 watts
2.4 power required by preamp/driver tubes = 20 watts (estimated)
2.5 total power required from power traffo secondary = 440 + 98 + 18.9 + 20 = 576 watts
2.6 required power traffo VA rating = 576watts/0.6 = 961 volt-amperes
2.7 as per RDH4, required power traffo must at least have a core area A(in square inches) equal to Sqrt(VA)/5.58, so A = [sqrt961]/5.58, or 5.56 square inches...there are many core sizes that can satisfy this requirement, i choose a core with 2 inch center leg, stacking to about 3.5 inches.
2.8 now that we have a core, we can now determine the required voltages...
2.9 Having a B+ of 750vdc means that that is the B+ at full power, so that we have to design for higher standby voltage, i select 75volts higher so that out B+ will idle at 825vdc....
2.10 Votage doubler will be employed, that the ac required then becomes 825vdc/2.8 = 294 volts...required current rating of this winding = 440/750 = 0.59A, using a #19 wire allows 1.8A at 700cm/ampere, way more than what is requried..
2.11 fixed biasing will be used and a bias or -45 volts will need a dc of more than 100volts or say 150volts, again this will be a voltage doubler type to enable the use of mosfet source followers to directly drive the grids of the QE08/200, required ac winding is 150/1.4 = 107volts ac, #24 wire is to be used here..
2.12 for the preamp and driver tubes, a separate 400volt dc supply will be required, ac winding is 400/1.4 = 286vac, #29 wire is to be used here.
2.13 we will calculate primary winding at 230volts ac, primary turns = 1750/6 = 291turns, we will use #16 wire, turns per volt t/v then equals 291/230 = 1.27turns per volt....
2.14 now we look at the filament windings, because of the huge filament currents, i decided to series connect the power tube's filaments, so that 12.8 volts is required, 16 turns #16 x 2 strands....
2.15 coil table summary:
primary......291turns of #16 magnet wire
secondary 1.......373 turns of #19 magnet wire
secondary 2.......135 turns of #24 magnet wire
secondary 3.......363 turns of #29 magnet wire
filament..........16 turns of 2 x #16 magnet wire
2.16 Estimated copper weight at 2kg and core steel weight at 10kg...this more or less completes our transformer design, actual number of turns tend to change during actual build, this is quite normal...


Very detail indeed.

Cheers :clap: :clap: :clap:
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Re: 6LU8 Push-pull power amp and other builds

Postby 0760.lorelei » Thu Sep 27, 2012 8:25 am

boss tony pwede pa quote ng trafo's and output transformer, im using a 2pcs EL84 output tube, 1pc 5U4G rectifier tube and 1pc 6D1p or 12AX7 for input tube....actually i use the ZEN TRIODE Model SE84cs schematic...pm pls how much para paghandaan ko yung payment :) mahal pala mag build ng tueb amp...hehehehe...thank you sir.
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Re: 6LU8 Push-pull power amp and other builds

Postby 0760.lorelei » Thu Sep 27, 2012 8:30 am

boss tony 300-0-300 150ma power trafos 240 vac 50/50 cycle yung power trafos used by decware sa schematic di ko alam sa output boss....hehehe thanks
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