Dx Troyan, a 650 watts channel amplifier.

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Troyan updated and upgrade schematic and pcboard

If you and bigger and better layout, then write to me asking.

Thank you Alexandru (Pop) that is helping a lot... a very important member from this Corporation you are.

regards,

Carlos
 

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Carlos,
With these powerful amplifiers you may have to modify the wife's clothes dryer to use as a load for testing. The main heater element in the dryer should be good for at least 1500 watts MINIMUM. Nice happy purely resistive load. Just what you need on a hot Brazilian summer -- more heat.

With the large number of outputs in this new layout I think you may have something that will stay together for many years. Those 2 ohm distortion tests look quite promising for something you have only been working on for a couple of months. Have you detecting any extremely high frequency oscillations with this layout? I would like to know what you have done to keep those in check.

Tad
 
It is a monster tryon... very strong.... i have not transformer to test it real

using 2 ohms and 1 ohm load...this was made using simulator only... voltage was reduce..supply voltage goes reducing while you reduce the output impedance not to have to increase the number of output pairs.... a good idea someone gave me...maybe Tinitus, i do not remember the one suggested the good idea.... same amplifier...but reducing supply voltage can face lower impedance loads.

The driver current is controled by the CCSs that are feeding these drivers... the bias control is increasing MORE the output...controling more the output, because drivers have a maximum fixed current fixed by the CCSs..one to each rail.

The idea is to adjust reading voltage over power emitter resistances..then 1 , 2 or 3 milivolts goes fine.... i have tested and i found 3 milivolts nice.... more current there, say 10mA, just increase heat and the amplifier starts to clip a little bit earlier (lower power than specified) because the "advanced" biasing point into the start up (iddle)

It is working fine.... problem is that windows goes shacking and enormous ventilation inside the speaker enclosure is breathing awfull MDF smell.... air pumped is big!

regards,

Carlos
 
The idea is to adjust reading voltage over power emitter resistances..then 1 , 2 or 3 milivolts goes fine.... i have tested and i found 3 milivolts nice.... more current there, say 10mA, just increase heat and the amplifier starts to clip a little bit earlier (lower power than specified) because the "advanced" biasing point into the start up (iddle)

It is working fine.... problem is that windows goes shacking and enormous ventilation inside the speaker enclosure is breathing awfull MDF smell.... air pumped is big!

Sir,...i mean guide set-up/adjust driver bias with manual schematic step by step

thanks
Hadita
 
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Carlos ,

Found the outputs at Mouser, these should work , correct ? ..



mjl1302a

mjl3281a


Do we have to use matched transistors ?


Regards,

If you buy all OP trannies at the same time from mouser they should be fairly close (2%) On- semi is consistant. Same for the input pair , same batch of transistors ..worst I have seen is 25mv offset (fairchild) 20% is not too good , would require a offset adjust trimmer to get even close.
OS
 
Carlos,
say that in your first recommendation.

"Match hFE using a DMM transistor hFE test to within 20%."

However, I don't agree.

I would recommend that the DMM hFE be used to batch similar devices. Then test hFE properly at the current expected in the operational circuit. Match these properly measured hFE @ XmA of Ic to better than 5%.

Then a second parameter match even more important than the hFE match.
Measure the Vbe vs Ic of these hFE matched devices.
Use a dual transistor jig. Apply a fixed Vbe to both transistors and measure the Ic flowing through each. Adjust Vbe until Ic = operational current. Choose devices that when Thermally Coupled and with Identical Vbe and Identical Vce pass Ic within better than 1%. These make a matched pair at that Ic.

I go further.
I swing the Vbe slightly either side to get matching percentages over a range of currents, maybe +-20% of operating Ic. Again hoping to see Ic matching to better than 1% over the range of Ic that I have tested.
BTW,
I do my matched jFETs in a similar manner. They really match to the specification I give.

When I install these matched pair I find they amplify very well and have very low output offset. When in the circuit (if properly designed) they have very similar Vce and very similar Vbe.
 
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