Parrallel/bridged LM4780 ??

pat allen · 22nd December 2006, 07:41 PM

Hi, i am browsing the chip amp solution and am looking at all possibilities...
TDA72xxx,...
I made some extensive search and didnt find what i was looking for...
So i came to LM4780, 2 channel in parralel and two of theses in bridged...
anyone ever did this ?? that could make a very cheap and very powerfull amp...

anyone?

pat allen · 23rd December 2006, 03:34 PM

nevermind plz, i found later the BPA200...

thanks.

Bicycleguy · 24th December 2006, 05:28 PM

I just built my daughter a guitar amp using Audiosector's 4780 kit and paralleled it. It has a tube preamp and drives 2 Eminence 12" speakers. It is very powerful! Great kit btw

lgreen · 27th December 2006, 06:57 PM

I've built one with no problems. Note that these need good heat sinking. Link to LM4780 Amp.

pat allen · 27th December 2006, 08:36 PM

wow, thaks guys for the comments...

do you have any pictures ?

what did you used to compensate the dc output, servo, adjustable bias,...

I have all these big toroidal transfos, caps and huge heat sinks...not to mention that big mofo penultimate zen that i build and that i dont use at all ...i could swap in a lot of these LM4780

thanks guys.

sangram · 28th December 2006, 04:00 AM

I did exactly what you said in your first post. I got two LM4780 kits from Audiosector, and set them up in the parallel mode on each chip. Then two boards are bridged (I have a soundcard with balanced output). I don't compensate for DC and there is no input cap. DC offset is 2mV on one channel and 6mV on the other. Have to really be confident of the fact that there is no DC on the input, else it'll cook the speakers...

It's reasonably cheap, very powerful (I estimate around 200 watts/channel) and not too bad-sounding either. The transformers are 440 VA EIs for each channel (this part of the world is still in the EI era), and I added 4700 uF per rail to the Audiosector kit's 1500uF. I had 10,000uF in there earlier, but I prefer it with less capacitance.

22nd December 2006, 07:41 PM	#1
pat allen diyAudio Member Join Date: Dec 2004 Location: Quebec	Parrallel/bridged LM4780 ?? Hi, i am browsing the chip amp solution and am looking at all possibilities... TDA72xxx,... I made some extensive search and didnt find what i was looking for... So i came to LM4780, 2 channel in parralel and two of theses in bridged... anyone ever did this ?? that could make a very cheap and very powerfull amp... anyone? __________________ Electronic engineer for automotive market.

23rd December 2006, 03:34 PM	#2
pat allen diyAudio Member Join Date: Dec 2004 Location: Quebec	nevermind plz, i found later the BPA200... thanks. __________________ Electronic engineer for automotive market.

24th December 2006, 05:28 PM	#3
Bicycleguy diyAudio Member Join Date: Oct 2006	Parallel fyi I just built my daughter a guitar amp using Audiosector's 4780 kit and paralleled it. It has a tube preamp and drives 2 Eminence 12" speakers. It is very powerful! Great kit btw

27th December 2006, 06:57 PM	#4
lgreen diyAudio Member Join Date: May 2003 Location: San Diego, USA	I've built one I've built one with no problems. Note that these need good heat sinking. Link to LM4780 Amp. __________________ My DIY audio projects- PartTimeProjects.com.

27th December 2006, 08:36 PM	#5
pat allen diyAudio Member Join Date: Dec 2004 Location: Quebec	wow, thaks guys for the comments... do you have any pictures ? what did you used to compensate the dc output, servo, adjustable bias,... I have all these big toroidal transfos, caps and huge heat sinks...not to mention that big mofo penultimate zen that i build and that i dont use at all ...i could swap in a lot of these LM4780 thanks guys. __________________ Electronic engineer for automotive market.


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28th December 2006, 04:00 AM	#6
sangram diyAudio Member Join Date: Sep 2002 Location: India	I did exactly what you said in your first post. I got two LM4780 kits from Audiosector, and set them up in the parallel mode on each chip. Then two boards are bridged (I have a soundcard with balanced output). I don't compensate for DC and there is no input cap. DC offset is 2mV on one channel and 6mV on the other. Have to really be confident of the fact that there is no DC on the input, else it'll cook the speakers... It's reasonably cheap, very powerful (I estimate around 200 watts/channel) and not too bad-sounding either. The transformers are 440 VA EIs for each channel (this part of the world is still in the EI era), and I added 4700 uF per rail to the Audiosector kit's 1500uF. I had 10,000uF in there earlier, but I prefer it with less capacitance.

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