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Ford_V6 22nd March 2003 08:49 AM

Hy to all of you guys !
Hy to all of you guys !

I'am a begginer in DYI audio electronics. The first amp i built was based on the TDA2040. ( don't laugh ). Then i wanted more power so i built an amp based on the 7250 and a pair of darlingtons tip142/47 / channel. Now i would like to know some things from the pro's :

- The power supply that gives me +/- 37 V uses 2 x 10000 Uf capacitors. Are the capacitors enough ? What are the good things in raising the capacitors value ?

- There is a better replacement for the 7250 ?

- With what darlingtons can i get the highes power from the 7250 ?

Thnks for helping.
I hope i don't bother with this rookie stuff,


Dj BASS AMP 22nd March 2003 02:06 PM

u can build a lot of powerful amps withe TDA7250...
AMP 1 400W
AMP 2 250w
AMP 3 400w
AMP 4 2x150w

Jay 22nd March 2003 07:04 PM

Iím not a pro:

- I think the most relevant advantage is for the capacitor to retain power when required to give a low powerful bass. Itís not only the capacitance value that is important. Capacitor quality must also be considered (Iím impressed with Panasonic for itís price to quality ratio)

- Donít know, but I doubt it. As long as it is in chip case, it must be class AB. When better performance is required, going discrete is I think the only choice.

- MJ11015 (PNP)/MJ11016 is the only replacement I ever used, and I think it is the best (in power and quality). It cost me 7X the TIP price (but this Motorolla is in TO-3 package).

And DJ, those links are broken.

Dj BASS AMP 22nd March 2003 09:24 PM

the links are good i check them now...

Jay 23rd March 2003 06:40 AM

Yes, DJ. They are fine now. But I can only understand the pictures.

Dj BASS AMP 23rd March 2003 11:12 AM


Originally posted by Jay
Yes, DJ. They are fine now. But I can only understand the pictures.

so me to understand only the pic....
i add them if he what to look in other amps of TDA

Ford_V6 23rd March 2003 07:51 PM

Thanks for helping me out here.

Now i ran into another problem. At +/- 38 V and RL=4 ohm. when i turn on the volume over a certain point the amp shuts down and when i lower the volume the amp waits a few secs and then turns on again.

What is the problem ?

Can be that the speakers can't take the load and the amp knows that and is shutting himself off for protection ?

Thanks again for help.

P.S. Great pictures of 7250 amps.

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