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Old 2nd February 2013, 09:41 AM   #511
wiljj78 is offline wiljj78  Philippines
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Default Preferred bias voltage for +/-38VDC

Uncle Charlie,

I have connected the amp supply @ +/-38VDC and i'm trying to set the bias on 10R/10W resistor but the max. voltage i can set is only 2.35V and the heatsink is warm.

Please advice what is the preferred bias voltage for +/-38VDC as my trimmer was on the maximum but bias voltage is only 2.29 on the positive rail and 2.33V on the negative rail and i'm not sure if this is the right bias according to the supply voltage.

Regards,
Wiljj78
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Old 2nd February 2013, 03:58 PM   #512
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Default It is all rigth Wiljj78... relax.... let it be this way as you're using 38 Volts

I am trying the Dx Supply once again, this time i have installed 25.000 plus 25.000uf, the amplifier is operating with 38 Volts, the supply voltage unloaded is 44 volts...loading it drops to 40 volts and keeps the output voltage stable...highly filtered as i tortured with 1 hertz and no noise from the supply, totally and absolutelly silent even when we drain high currents.

Speaker is using 4 ohms coil (it is dual coil) and i have pushed almost 100 watts RMS... due to 6 volts of voltage drop into the series pass transistors (from colector to emitter) i am having some heat into my test small heatsinks.... but when draining high current the voltage drop into series pass transistor is only 2.3 volts...this way heat is not that big.

Circuit is Dx Super A operating with one single pair in the output and i cannot push it hard because of that.... 100 watts only a few seconds.

As you can see, i have simplified the supply to enjoy it's power while i am waiting more transistors, pcboards and electrolitic condensers.

Just to be listening the Dx Super A and to have fun.

regards,

Carlos
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Old 2nd February 2013, 04:47 PM   #513
wiljj78 is offline wiljj78  Philippines
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Default Uncle charlie i will keep the bias in 2.0V while i'm using

Temporary heat sink, but I will set and readjust the bias in max to get 2.33V when I move to the final heat sink, so far the heat sink is little hot when i supply +/-38VDC but the amp looks stable and I feel comfortable and nothing to worry about....
Today Iím having fun with super A and really it has lots of power as I canít push it hard to the max volume I can feel my speakers canít survive the power, otherwise will be sorry HahahahaÖ.

Regards,
Wiljj78

Last edited by wiljj78; 2nd February 2013 at 05:03 PM.
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Old 2nd February 2013, 05:30 PM   #514
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Default Decrease the value of the resistor you have in series with the trimpot

then you current will go up...but i do not think you should...you can do it, but this will not change that much the amplifier performance.

It is better to enjoy the sonics than to go tweaking...it is time to have fun..not to be working hard.

regards,

Carlos
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Old 2nd February 2013, 08:13 PM   #515
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Default I am having fun listening music....nice result with the Dx Supply

Sound is more clean when you push it hard.

regards,

Carlos
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Old 2nd February 2013, 08:31 PM   #516
wiljj78 is offline wiljj78  Philippines
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Default Thats cool uncle Charlie....

I’d like to build your DX supply, do you think it gets more benefit for my Super A even my supply is under voltage? I mean I only have 29-0-29VAC.
Regards,
Wiljj78
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File Type: jpg Super SANKEN version 2.jpg (251.8 KB, 264 views)
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Old 2nd February 2013, 09:41 PM   #517
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Default It is up to you, i have already informed the advantages

If you intend to push it hard, then you need an electronic fllter and stabilizer to the supply voltage...if you do not push the amplifier hard...then condensers will be enough.

By the way...nice pictures..thank you as you are sharing with us.

Also thank you by your preference in Dx amplifiers.

I just cannot decide in your place, or by you..it is up to you.
regards,

Carlos
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Old 2nd February 2013, 10:05 PM   #518
wiljj78 is offline wiljj78  Philippines
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Default My pleasure Uncle Charlie and thank you also for sharing this Super A

Yes and I have noted those advantages you have posted, but in my case I just want to hear your opinion of coarse as a master of DX corporation its valuable for me every single information you have had shared in this forum, I have built your MKIII HX and I love it more than any of my amplifier but sorry to say this Super A is my favorite now….

Regards,
Wiljj78

Last edited by wiljj78; 2nd February 2013 at 10:11 PM.
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Old 3rd February 2013, 07:24 AM   #519
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Default Yes.... we feel it better than previous models

This is clear to me it is the best i have made.

About the supply, i have to check, i have made some modifications.... hold on for a couple of weeks till i have finish my research.

It is under test in my main system (computer audio amplification)... and i want to torture a little bit more, also i want to see voltage drift from the previously made adjustment, heat and some other details.

I may change something into the resistor network that feeds the output darlington that works also as a capacitance multiplier...i have to find a better compromise in between filtering and speed of attack/delay.

For a while...all i had as benefit is that i can put 1 cicle per second, full power and i have not noise from mains.... really?.... this is not that impressive....i want more and i could not feel all that advantage in dinamic sound reproduction...... i perceived it looks more clear... a little bit...so, i have to understand, and to find out, the real advantage of disadvantage because these parts also have a cost, another pcboard, some huge electrolitics, series power transistors... all this needs some study, some tests, some cost calculations and some reflections about.

You know... real life people does not goes listening (cannot even listen) one hertz full power... i want to figure out the advantage in real use..because this one hertz is just academic.... nothing that may change our listening experience..... i have to calculate if this saves money or not, as you can install a huge bank of electrolitics to have something alike.... not the voltage regulation, but the filtering.

The real work is post simulation.... after the simulation all starts...and the results depends on that, not from the simulator...things must make sense, must have decent cost/performance ratio.

regards,

Carlos

Last edited by destroyer X; 3rd February 2013 at 07:32 AM.
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Old 3rd February 2013, 11:53 AM   #520
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Default I will be listening music at home this Sunday

My twin speakers are playing nice bass.... and good mids and treble too.

regards,

Carlos
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