100W Ultimate Fidelity Amplifier

[desislavov]

This is the output stage on apex 100 W amplifier with current protection /short circuit/
what do you think ?

Тoday I solder protection under this circuit and everything works.
I short output and nothing burns

http://www.diyaudio.com/forums/atta...w-ultimate-fidelity-amplifier-100wprotect.jpg

 

[stocktrader200]

on AX 14 Amplifier, what happens to the distortion if Q6 and Q8 ( VAS Stage) are replaced with an irf610 mosfet with 7.5v gate protect zener where D1 is

 

[maxwell007]

So I finally revived A40 .. square at 20khz and 50khz...very clear sound with good bass..

 

[maxwell007]

short movie
https://youtu.be/n7i6otEndsM

 

[alex mm]

.....excellent work ,

 

[vargasmongo3435]

wow bro ! nice !

 

[apexaudio]

So I finally revived A40 .. square at 20khz and 50khz...very clear sound with good bass..

Nice work, regards.

 

[maxwell007]

Thanks guys...so, I have to make some chassis...I gonna also use my two 300VAC transformers with 29AC.. I hope that will be enough.

 

[danielturcu]

What power will have at 29AC? 70-80W 8R?

 

[AndrewT]

Calculate it.

29Vac gives ~ 1.4*29 as your loaded DC voltage, i.e. around 40Vdc
two times 29Vac gives around +-40Vdc when loaded.

Assume 4V lost through the amplifier when delivering maximum power.
i.e. maximum output ~35Vpk

Maximum power = Vpk²/Rload/2
i.e. 35²/8/2 = ~76W into 8r0 dummy load. If you build the PSU and amplifier properly.

 

[danielturcu]

Ok .... @AndrewT, thanks for explaining, as PSU for this amplifier I have bought two toroidal transformers (45VAC - 200W for each channel). All i need is time to build it. @ maxwell007 how is bias adjustment? It's easy? Did you encountered problems?
Regards Dan.

 

[AndrewT]

45Vac+45Vac is high.
45Vac centre tapped is low.

 

[still4given]

I have run this amp between +-25vdc and +-50vdc. +-50vdc is pushing it for 4ohm. 45-0-45vac is way too much for this amp.

 

[maxwell007]

I had problems just with my own stupidity one short, and substitution BC.. there is no problem with build and setting...

 

[danielturcu]

I have the possibility to change the transformers twith two toroidals (2x40VAC, 200W/ channel). The speakers are 8 ohms impedance......

 

[still4given]

Hi Daniel,

I didn't see which amp you are building. 40-0-40vac transformer will give about +-56V unloaded so about +- 52-54vdc rails. Too much for one pair of output transistors. You need to build one of the ones with at least two pairs.

 

[danielturcu]

Sorry...., the amp in discussion is A40, with the layout made by @Alex. Thank's for the advices @still4given .
Regards.

 

[still4given]

That transformer will work well with the A40. I have run the A40 on +-63v without issue.

 

[maxwell007]

So, I found some 2x36V 300VAC transformers....it will be +-50v and i hope that will be enough...It should be cca 130W to 8r..

 

[AndrewT]

35Vac dual secondary are the normal retail.
36Vac would be a special.

for a target output of ~130W you would need nearer dual 40Vac (standard retail), maybe 38Vac (special) would get to 130W into 8r0.