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Old 26th August 2010, 12:05 PM   #1
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Default Want to build a 300 watt stereo power amp

Hi folks,

After having sucessuflly built a 2x30watt amp, I'm now interested in building a 300 watt Stereo power amp. I'd like to build a 2 x 150 watt (approx) circuits into a 19" rack type case.

Can this be done with say 2 x LM3886 chips on each circuit? If so, does anyone have or can recommend any schematics or PCBs.

Thanks in advance.
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Old 26th August 2010, 03:56 PM   #2
AndrewT is offline AndrewT  Scotland
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if you have learned enough from your first build you must realise the voltage and current limits of the chipamp you propose to use.

Apply those voltage and current limits to your 150W design idea to drive a reactive speaker load and see why it can't easily be done.
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Old 26th August 2010, 04:53 PM   #3
ChrisA is offline ChrisA  United States
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Quote:
Originally Posted by AudioMike View Post
Hi folks,

After having sucessuflly built a 2x30watt amp, I'm now interested in building a 300 watt Stereo power amp. I'd like to build a 2 x 150 watt (approx) circuits into a 19" rack type case.

Can this be done with say 2 x LM3886 chips on each circuit? If so, does anyone have or can recommend any schematics or PCBs.

Thanks in advance.
First, Why 300W? How did you determine you need that much power? Maybe you don't. There are good resons for needing a big amp. I need one also but do make sure you have one of those reasons or you will just waste your money. In my case I happen to own a pair of hugely in-efficient and large 1970's vintage Infinity speakers. I'm working on a tube based design of about 100 WPC.

At 300W you are pretty much out of the "chip amp" range. But if you want something very much like a chip amp, in that all you do is add power, a chassis and connect it up then look at this
PM224 MOSFET Power Amplifier Module, High Voltage Power Amplifier

Last edited by ChrisA; 26th August 2010 at 05:11 PM.
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Old 26th August 2010, 05:19 PM   #4
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Quote:
Originally Posted by ChrisA View Post
First, Why 300W? How did you determine you need that much power? Maybe you don't. There are good resons for needing a big amp. I need one also but do make sure you have one of those reasons or you will just waste your money. In my case I happen to own a pair of hugely in-efficient and large 1970's vintage Infinity speakers. I'm working on a tube based design of about 100 WPC.

At 300W you are pretty much out of the "chip amp" range. But if you want something very much like a chip amp, in that all you do is add power, a chassis and connect it up then look at this
PM224 MOSFET Power Amplifier Module, High Voltage Power Amplifier
There are ways to get more power with chip-amps...you just have to know how to do it. Take a look:

http://www.national.com/an/AN/AN-1192.pdf

Scott
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Old 26th August 2010, 05:32 PM   #5
jerryo is offline jerryo  Isle of Man
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Hi,
try the "Lynx" amp by Jan Dupont. If for no other reason his build instructions from his website are excellent. Actually the best instructions that I have come across) It's a very powerful amp and there is a pcb group buy going on at the moment.

It's not a chip amp but check out the specifications and decide for yourself.
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Old 26th August 2010, 10:01 PM   #6
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Default Possible ?

The LM4780 gives something like 65 Watts into 8 Ohms .
Could you connect a pair together on each side , giving
130 Watts / Channel into 8 Ohms ? That would be close !

David V. Webber
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Old 26th August 2010, 10:24 PM   #7
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audio mike,
Having been successful with the low power chip amps you could try to build an amp with the lme498xx chips. they have very high voltage ratings and a member on this forum pansonaudio.com has some very nice kits available.
You will be getting your first try at a semi discrete setup and have a very nice amp when completed. National states these chips can be built to over 500 watts. This should put you in the power territory you want.
Just a note the Jeff Rowland chip amp running 6 lm3886 devices in bridge parallel was rated at 300 watts into 4 ohm loads. I have built this amp and can tell you it sounds very good but gets too hot when run hard on troublesome speakers. You can find pcb's for this Jeff Rowland clone here at diy audio. If you go to shine7.com you can read all about this clone.

Tad
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Old 26th August 2010, 10:35 PM   #8
ChrisA is offline ChrisA  United States
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Quote:
Originally Posted by SpeakerScott View Post
There are ways to get more power with chip-amps...you just have to know how to do it. Take a look:

http://www.national.com/an/AN/AN-1192.pdf

Scott
Yes, I know a series/parallel setup would work for him. But for a 300W stereo amp he'd need a total of as many as ten chip amps. May as well use mosfets. But we don't know what he needs maybe he as an 8 ohm load or maybe 4 ohm, maybe 100WPC is OK?
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Old 26th August 2010, 10:42 PM   #9
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Quote:
Originally Posted by ChrisA View Post
Yes, I know a series/parallel setup would work for him. But for a 300W stereo amp he'd need a total of as many as ten chip amps. May as well use mosfets. But we don't know what he needs maybe he as an 8 ohm load or maybe 4 ohm, maybe 100WPC is OK?

He said 300W stereo, but then said 2x150..so I thought the BPA amp would work for him.

-Scott
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Old 27th August 2010, 01:43 AM   #10
star882 is offline star882  United States
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Quote:
Originally Posted by ChrisA View Post
At 300W you are pretty much out of the "chip amp" range.
TI makes some good for up to 600W per chip.
Digital Amplifier Solution - Analog Input Class D Amplifier - TAS5630 - TI.com
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