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Old 16th November 2012, 02:25 PM   #191
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10 jumpers against only 2 in previous design (DX Blame SC), for only minor differences between schematics. Isn't it time for some rearrangement?
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Andres
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Old 16th November 2012, 02:46 PM   #192
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Yes dear friend I try to avoid them but I didn't have much options to keep alignments is hard to keep align components and symmetrical at the same time. Let me add one more thing, if uncle Charley is happy with the results and happy too.

Regards
Juan

Last edited by vargasmongo3435; 16th November 2012 at 02:50 PM.
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Old 16th November 2012, 05:11 PM   #193
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Old 16th November 2012, 07:37 PM   #194
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Default Yes ... i am very happy ... and another friend is testing

The Dx Super A with Fets in the output... stand by current around 800 mA each rail.

It is Naldo, from my new wonderfull Brazilian forum.

regards,

Carlos
Attached Images
File Type: jpg Dx com Fets.jpg (238.6 KB, 562 views)
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Power supply; ripple, filter, noise, stability and the use of capacitance multiplier... Portuguese and English; https://www.youtube.com/watch?v=sSm0ku1eIgg
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Old 16th November 2012, 08:41 PM   #195
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Default I said i am very happy with Juan performance

Satisfied i am with Juan work.... i love each jumper he installed, all them made with my supervision and approved by the Corporation.

We have other foruns, i have some brazilian foruns, in one of them a friend asked me to allow him to develop an output using Fets, as another option and another pcboard that Zimmer will make.

In the reality i gave to the man the scratch of the amplifier, already simulated and with very low harmonic distortion and excelent harmonic distribution to be tweaked, tuned for even better performance while listening.... the guy, the Brazilian, called Naldo, will do that.

Zimmer, the german (South of Brazil) is producing pcboard layout too, more dedicated to feed his own friends in his own town.

Zimmer will make modifications in his pcboard, producing another one, to give folks the option to use Fets in the output.

The main official pcboard layout designer to the Dx Corporation, to international foruns and to the Dx Super A, is Mr. Juan Vargas, from Porto Rico.

Juan can provide boards, if he want, to anybody and anywhere.

Also my brazilian friends can provide boards to anybody and anywhere, but they have made to sell them in Brasil, or to sell them wide world, only if Juan decide not to provide pcboards to the comunity.... then they will have my ok to move on.

regards,

Carlos
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Power supply; ripple, filter, noise, stability and the use of capacitance multiplier... Portuguese and English; https://www.youtube.com/watch?v=sSm0ku1eIgg

Last edited by destroyer X; 16th November 2012 at 09:02 PM.
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Old 17th November 2012, 07:02 AM   #196
wiljj78 is offline wiljj78  Philippines
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Default +/-42V Regulated PSU

Uncle Charlie,

What about regulated PSU for Super A? Any update?

As I believed this required specifically +/-42VDC.

Regards,
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Old 17th November 2012, 01:58 PM   #197
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Default I have tested today, it is all right, the Super A and the supply together

Today i have adjusted the stand by current (class A current) to 0.7A each rail.... sound is perfect.

Well, this thing is hot, reason why i am using fan....videos are in portuguese, because of that i am avoiding to post links of portuguese videos here.

Here you have the schematic, tested, approved and working great.

My transformers are having a voltage drop when i drain 150 watts per rail, then my DC out is 36 volts to each rail (under load conditions)...because of that i have adjusted the supply output to 30 volts in order to let 5 or 6 volts to allow the regulator to operate...then i had, during test, 6A to each rail (180W) and the voltage drop was 0.1 to 0.2 volt...so, calculate and you will see it really stabilizes the voltage, in special to Class A as current does not variate to much fast...the 3300uf condenser make this circuit slow, to use together AB amplifier it is better to reduce it to 220uf.

To operate this supply you have to connect DC rectified (by diodes) to the input that is in the left side..then you adjust the trimpot to the voltage you want.... transformer is 30 plus 30 AC volts... you do not need filters... the input 10.000uf per rail will be enougth to 150 watts per rail, and no AC mains frequency noise appear in the output (very small noise, almost nothing)

Use heatsinks to your output transistors...i am using three in parallel to each rail...also i am using power equalizing resistors in series with these transistor emitters (0.22 ohms or 0.33 ohms)

To know the power you will have drained from this regulator, them make the series pass power transistor colector voltage - (minus) emitter voltage and them multiply by the current...then you will have the power developed into the series power transistors..use an aluminium blade measuring 10 by 10 centimeters (squared and 1.0 to 1.5 milimeters thick) to each 10 watts of dissipation.... or equivalent.

In my case i am draining only 2 amperes each rail...input voltage is more or less 38 Volts under this condition, and i have adjusted to 30 volts my output voltage.... so, i have 8 volts multiplied by two that results in 16 watts each rail of heat.... i need 4 blades of aluminium to solve my problem.

regards,

Carlos
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File Type: jpg Fonte regulada.jpg (131.6 KB, 498 views)
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Power supply; ripple, filter, noise, stability and the use of capacitance multiplier... Portuguese and English; https://www.youtube.com/watch?v=sSm0ku1eIgg

Last edited by destroyer X; 17th November 2012 at 02:04 PM.
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Old 17th November 2012, 02:19 PM   #198
wahab is offline wahab  Algeria
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Since i got recently a JVC amp of average construction for free i m tempted
to get the Super A VC5022 part for my mosfet amplifier but before proceding ,
i would be curious if your discrete implementation (used in the AX5) works
accurately.

In principle the idling current is about 50mA , the Super A circuit role
is just to keep both output devices conducting whatever the output power ,
hence it is a non switching circuit.
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Old 17th November 2012, 02:35 PM   #199
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Default My circuit is not used in this model.... well, at least i have made by myself

It is just a zener sending positive voltage to the VBE multiplier base when we reach a couple of watts in order to reduce the DC stand by current (bias) to the normal level i use into the Dx Blame ST....in other words, it is a Class AB amplifier and i have adjusted the current to the output transistors to 250 mA to each rail, or 500mA to each rail....today i have tested using 700mA to each rail.... when i crack the volume up, the ouput line voltage crosses the zener diode, and then two attenuating resistors and this feed more current to the VBE multiplier transistor base that readjust its operational point reducing the current to 20ma per rail.

Just that... a very simple circuit, a zener, one 1N4148 diode, one capacitor and two resistors...this feeds the VBE multiplier transistor base with positive voltage.... this reduces the ddp from colector to emitter reduing the bias to the output transistors....the VBE multiplier is standard.

JVC uses a much more sophisticated and complicated circuit, i do think mine do the job...just that.

regards,

Carlos
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Power supply; ripple, filter, noise, stability and the use of capacitance multiplier... Portuguese and English; https://www.youtube.com/watch?v=sSm0ku1eIgg
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Old 17th November 2012, 02:55 PM   #200
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Default Here you see.... you adjust the bias trimpot to

700mA each rail, then we increase the volume..when the zener diodes senses 6 watts RMS it starts to conduct and goes reducing the current...at 70 watts the DC current is 33mA per rail.

Very simple, and because of that it is very good.

regards,

Carlos
Attached Images
File Type: jpg Dx Super A.jpg (69.2 KB, 409 views)
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Power supply; ripple, filter, noise, stability and the use of capacitance multiplier... Portuguese and English; https://www.youtube.com/watch?v=sSm0ku1eIgg
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