Push and pull power amplifier

Wasim · 22nd April 2009, 04:20 AM

Hi All,

I found this diagram over the net. I just would like to build this amp. But I just would like to take some experts opinion will this amp work and also see its PCB. Thanks in advance.

Regards

Wasim · 22nd April 2009, 04:27 AM

Here is its PCB...

Regards

ostripper · 22nd April 2009, 04:39 AM

Will most likely work , but at a crude level. Offset will be present,
crude thermal tracking , same as this amp...
What's this Amplifier Design

With current sources , a real Vbe , triple EF and proper compensation you have this :
http://users.ece.gatech.edu/~mleach/lowtim/
Thousands have built the good professor's design , so it is valuable reading for this particular topology.
OS

jaycee · 22nd April 2009, 10:50 AM

WE could call this "Leach Amp Done Badly".

No emitter resistors on the outputs. No proper output stage biasing. No current sources on the LTP's... not to mention exposing the LTP transistors to the full rail voltage without cascodes. Oh, and 2 pairs of flatpack outputs on 63V? I dont think so.

The PCB layout is atrocious. The bias diodes aren't even on the heatsink! I'd be surprised if it actually worked for more than 5 minutes.

wg_ski · 22nd April 2009, 01:07 PM

Without any bias in the outputs, it would work for more than 5 minutes. It will sound awful, but I doubt that it would run away with the bias at only 2Vbe where 3.5 to 4 is needed.

Wasim · 18th June 2009, 04:01 AM

Hi There

Thanks a lot of all experts for their valuable feedback. here is another amp diagram found over the net. Please`tell me about this. Is it worth to develop this amplifier.

Can anyone tell me:

can I use NPN and PNP transistors instead of N-channel and P-channel mosfets? I mean is there any difference between them?

like they are using (N)2sk1058 and (P)2sj162, can I use C4468 and A1695?

Regards

you can view the complete project here
http://diyaudiotr.com/islecler/tammetin.php?metinid=7

Wasim · 18th June 2009, 04:45 PM

hi,

I need experts' opinion please reply

regards

sakis · 18th June 2009, 09:08 PM

stated in both of these circuits are only theoretical
you will vever be able to produce this ammount of power in a reactive load such is a speaker

the nico ras amplifier is by far better than the one originaly posted but will never make this numbers of 380w at 4 ohms and working for a long time probably as a pa amplifier ....

cheap power is not an easy thing

it would be better to state your application and then a circit is going to be sugested

finally NO YOU CANNOT REPLACE MOSFETS WITH SIMPLE BJT A1695 AND 4468 !!!!

by this i can tell that your expirience must be very low and high power amplifiers are not an easy thing for a beginer ....

Wasim · 19th June 2009, 04:25 AM

Quote:

Originally posted by sakis
stated in both of these circuits are only theoretical
you will vever be able to produce this ammount of power in a reactive load such is a speaker

the nico ras amplifier is by far better than the one originaly posted but will never make this numbers of 380w at 4 ohms and working for a long time probably as a pa amplifier ....

cheap power is not an easy thing

it would be better to state your application and then a circit is going to be sugested

finally NO YOU CANNOT REPLACE MOSFETS WITH SIMPLE BJT A1695 AND 4468 !!!!

by this i can tell that your expirience must be very low and high power amplifiers are not an easy thing for a beginer ....

Hi Thanks for the reply. You are right I am not an electronics guy

but I have a hobbit to ask questions.

I have built 3 high power amps and they are working very well. Like Nmos350 / 500.
Once I built a small amp with the same topology and that amplifier works really well; with 32VDC rail it produces something like 180W rms into 4ohm load. Although I do not have any equipment to judge the expect power but I compare it with my UCD Class D amplifier. That's why I thought with 55VDC rail this nico ras amplifier might give good power.

Regards

Wasim · 19th June 2009, 04:31 AM

Quote:

Originally posted by sakis
stated in both of these circuits are only theoretical
you will vever be able to produce this ammount of power in a reactive load such is a speaker

the nico ras amplifier is by far better than the one originaly posted but will never make this numbers of 380w at 4 ohms and working for a long time probably as a pa amplifier ....

cheap power is not an easy thing

it would be better to state your application and then a circit is going to be sugested

finally NO YOU CANNOT REPLACE MOSFETS WITH SIMPLE BJT A1695 AND 4468 !!!!

by this i can tell that your expirience must be very low and high power amplifiers are not an easy thing for a beginer ....

Hi sakis,

I missed one thing I am looking for a circuit that gives 200Wrms in 8ohm with 60VDC rail. and it is going to be a hifi home audio amplifier not PA.

Regards

18th June 2009, 09:08 PM	#8
sakis diyAudio Member Join Date: Jan 2006 Location: nea makri athens greece	the ammount of power stated in both of these circuits are only theoretical you will vever be able to produce this ammount of power in a reactive load such is a speaker the nico ras amplifier is by far better than the one originaly posted but will never make this numbers of 380w at 4 ohms and working for a long time probably as a pa amplifier .... cheap power is not an easy thing it would be better to state your application and then a circit is going to be sugested finally NO YOU CANNOT REPLACE MOSFETS WITH SIMPLE BJT A1695 AND 4468 !!!! by this i can tell that your expirience must be very low and high power amplifiers are not an easy thing for a beginer .... __________________ SERVICE ΙΑΠΩΝΙΚΩΝ ΜΗΧΑΝΗΜΑΤΩΝ ΗΧΟΥ www.eastelectronics.gr

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22nd April 2009, 04:39 AM	#3
ostripper diyAudio Member Join Date: May 2008 Location: Albany , NY (smallbany)	Will most likely work , but at a crude level. Offset will be present, crude thermal tracking , same as this amp... What's this Amplifier Design With current sources , a real Vbe , triple EF and proper compensation you have this : http://users.ece.gatech.edu/~mleach/lowtim/ Thousands have built the good professor's design , so it is valuable reading for this particular topology. OS

22nd April 2009, 10:50 AM	#4
jaycee diyAudio Member Join Date: Apr 2004 Location: Norwich, UK	WE could call this "Leach Amp Done Badly". No emitter resistors on the outputs. No proper output stage biasing. No current sources on the LTP's... not to mention exposing the LTP transistors to the full rail voltage without cascodes. Oh, and 2 pairs of flatpack outputs on 63V? I dont think so. The PCB layout is atrocious. The bias diodes aren't even on the heatsink! I'd be surprised if it actually worked for more than 5 minutes.

22nd April 2009, 01:07 PM	#5
wg_ski diyAudio Member Join Date: Oct 2007	Without any bias in the outputs, it would work for more than 5 minutes. It will sound awful, but I doubt that it would run away with the bias at only 2Vbe where 3.5 to 4 is needed.

18th June 2009, 04:45 PM	#7
Wasim diyAudio Member Join Date: Aug 2007 Location: Lahore	hi, I need experts' opinion please reply regards

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