6LU8 Push-pull power amp and other builds

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

Postby tony » Sun Oct 14, 2012 10:46 am

0760.lorelei wrote: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


your traffos will be ready for pickup this coming weekend.......
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Re: 6LU8 Push-pull power amp and other builds

Postby tony » Sun Oct 14, 2012 10:51 am

please note that i am not really into the business of selling traffos.....that is my friend Edrel's turf.....i do help other budding diy'ers interested in learning how to make one.....http://www.elab.ph/forum/index.php?topic=17495.0 and http://www.diyaudio.com/forums/power-su ... ild-7.html
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QE08/200 push-pull amp.monoblocks.

Postby tony » Thu Oct 18, 2012 8:11 am

3. Design of output traffo:

3.1 looking at typical traffo designs on the web, a 300 watt traffo tends to be bulky, here is choose to use a 1 3/4 inch center leg, 0.35mm Z11(M6) cores.....
3.2 a 3 inch nylon bobbin is used here....so with with a 3 x 1.75 inch core area, power handling (as per RDH4) at 60hz is given as 860 watts, so that at 30hZ, this is about 430 watts,and at 20hz about 290 watts....use of this type of core arrangement is to my mind justified....
3.3 Anode to anode load is given as 3500 ohms, 4, 8 and 16 ohm secondaries are provided to accommodate various speaker power and impedance configurations....these are completed output traffos: Image
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Re: 6C33 Russian SET final...

Postby tony » Sun Oct 28, 2012 8:07 pm

with fuses installed, power to the output traffo and output tubes are complete....the 3 minute delay timer shorts out the 12k/5W soft start resistor...this resistor is in series with the main B+ ac supply....voltages ramps up to about 100 volts and stays there until the 3 minute timing period is reached, this protects the output tube from thermal run-away, at the same time that the plate B+ is ramping up, the negative bias voltage is likewise ramping up and settles to a value around -75 volts....these steps ensures successful turn on of the amp....

at the end of the 3 minute timing period, the relay closes and the 12k resistor is shorted out thus the B+ finally ramps up to around 210volts dc.....it takes another 5 minutes for the plate current to reach about 200mA....i recommend to wait for 10 minutes before music is played to give time for the amp to settle down to business....

i set the bias pots for this plate current level and bias drift was observed...i am happy to report that drifts were minimal and after 2 hours the bias current actually goes down a bit by around 10mA....this is normal as plate voltages in triodes have an effect on plate currents.....

i also observed that bias changes were caused by changes in line voltages.....


set-up for final adjustment to bias the output tubes.....

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with my power meter monitoring the ac input to the amp, power factor was at 92%.....

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total watts measured at 218watts...

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line current....

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thermal scan of the bulb at socket side underneath the chassis, i have installed fans running of 7 volts dc to move a bit of air underneath the amp when bottom plates are installed...
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Re: 6LU8 Push-pull power amp and other builds

Postby tony » Tue Oct 30, 2012 10:53 am

the amp is now with Trod93, if you want to hear the amps, please get in touch with tukayo.... :D
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Re: 6LU8 Push-pull power amp and other builds

Postby tony » Thu Nov 01, 2012 11:05 am

coming soon.....ClassAB2 6HF5 push-pull power amp, tube complements also include 6SN7.6H8C cathode followers dc coupled to output tube grid, 6BH11 gain and phase splitter, 6R-RH8 input buffer...this amp can do 70 watts easy.....140watts(to be confirmed)with the right tap...

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

Postby tony » Sat Nov 10, 2012 8:32 am

i will be at the Dusit Hotel today and tommorow, if you like to see my creations up close and personal, please be there.... :D
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Re: 6LU8 Push-pull power amp and other builds

Postby tony » Fri Nov 16, 2012 3:43 pm

as a token of my appreciation for being able to display my stuff at the hifi show, i am giving the DIY community a gift..... watch out for it...;D
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Re: 6LU8 Push-pull power amp and other builds

Postby tony » Wed Nov 21, 2012 1:31 pm

malapit na...... :D
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Re: 6LU8 Push-pull power amp and other builds

Postby Jon Agner » Wed Nov 21, 2012 1:46 pm

I was about to ask for your number :) :) :)

Di ako nakadaan last weekend due to an errand, but will try dropping by soon :)
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Re: 6LU8 Push-pull power amp and other builds

Postby kabubi » Wed Nov 21, 2012 3:29 pm

tony wrote:as a token of my appreciation for being able to display my stuff at the hifi show, i am giving the DIY community a gift..... watch out for it...;D


RAFFLE???

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

Postby tony » Wed Nov 21, 2012 5:19 pm

kabubi wrote:
tony wrote:as a token of my appreciation for being able to display my stuff at the hifi show, i am giving the DIY community a gift..... watch out for it...;D


RAFFLE???

:?: :?: :?:


much better than a raffle, kasi sa raffle there is only one winner, what i have in mind is for as many DIY'ers to win should they wish... :D
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Re: 6LU8 Push-pull power amp and other builds

Postby dimfer » Thu Nov 22, 2012 6:22 am

very nice posts/share Tony... more power to you and your DIY projects :rock:
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Re: 6LU8 Push-pull power amp and other builds

Postby brainf » Thu Nov 22, 2012 1:00 pm

tony wrote:
kabubi wrote:
tony wrote:as a token of my appreciation for being able to display my stuff at the hifi show, i am giving the DIY community a gift..... watch out for it...;D


RAFFLE???

:?: :?: :?:


much better than a raffle, kasi sa raffle there is only one winner, what i have in mind is for as many DIY'ers to win should they wish... :D


This is classic TonyT. Such a pleasure to have finally met you in person at the HiFi show!
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Re: 6LU8 Push-pull power amp and other builds

Postby tony » Thu Nov 22, 2012 1:36 pm

Jon Agner wrote:I was about to ask for your number :) :) :)

Di ako nakadaan last weekend due to an errand, but will try dropping by soon :)


yes, please do call first....i will be out of the house on weekends... :)
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Re: 6LU8 Push-pull power amp and other builds

Postby tony » Thu Nov 22, 2012 1:37 pm

dimfer wrote:very nice posts/share Tony... more power to you and your DIY projects :rock:


thanks, a push-pull 6C33 amp is in the works, good for about 80wpc....
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Re: 6LU8 Push-pull power amp and other builds

Postby tony » Thu Nov 22, 2012 1:38 pm

brainf wrote:This is classic TonyT. Such a pleasure to have finally met you in person at the HiFi show!


same here.....when are you doing your first tube amps? ;)
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Re: 6LU8 Push-pull power amp and other builds

Postby tony » Sat Dec 15, 2012 7:12 am

traffo testing:

this is the traffo under test:
center leg of 2 inches stacked to 3 3/4 inch thick, core rating as per RDH4 is about 1750volt-amperes,
the traffo has since been finished with "poly-tuff" automotive filler and painted matte black.....

the purpose of this post is to demonstrate the open circuit(core loss) and short circuit(copper loss) testing of power traffo
to find out efficiencies under load, currents from 1A to 7A were used....

although core rating is 1750VA, i will rate this traffo as a 1200watt power traffo....

Image


no load or open circuit testing using a kill-a-watt tester, in this test all secondaries of the traffo are left open...

no load current:

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no load energy stored:
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short circuit testing or copper loss test:

in this test all secondary winding's are joined together to form a short, a variac and my test contraption is used,
testing at several point from 1A to 7A....

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i attach a small spreadsheet showing copper losses at currents from 1 to 7amperes:

http://www.diyaudio.com/forums/attachme ... esting.zip
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Re: 6LU8 Push-pull power amp and other builds

Postby tony » Sat Dec 22, 2012 11:46 am

finished a pair of OPT's for 6C33 push-pull amp, 800ohms anode to anode to 2, 4, 8 ohm secondary with cathode feedback winding...

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

Postby tony » Wed Jan 16, 2013 8:09 pm

this a 6AV5 push-pull power amp pentode output, G2 regulation....for livening up shortly....

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