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Old 30th January 2004, 10:28 PM   #1
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Default Bridged and Parralleled to drive two ohm load

I have searched the forum, but i have not found any information about people using gainclones with two ohm loads. i have tried bridging and parralleling four chips (OPA548, OPA541, and OPA549), which will run a four ohm load safely. would i need to bridge and parrallel eight chips to get a safe output into a two ohm load?

i realise the power supply, and heatsink for this sort of amp would be huge, and this question is purely theoreticle(spelling?).
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Old 31st January 2004, 01:20 AM   #2
GregGC is offline GregGC  Canada
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Default Re: Bridged and Parralleled to drive two ohm load

Quote:
Originally posted by Matttcattt
I have searched the forum, but i have not found any information about people using gainclones with two ohm loads. i have tried bridging and parralleling four chips (OPA548, OPA541, and OPA549), which will run a four ohm load safely. would i need to bridge and parrallel eight chips to get a safe output into a two ohm load?

i realise the power supply, and heatsink for this sort of amp would be huge, and this question is purely theoreticle(spelling?).

You'd need to bridge them if you are driving loads more than 8Ohms load or you have limited PS voltage (car amps). That way you have double the amount of voltage across the load. In your case look at paraleling only. I don't see a reason to bridge them. You have enough voltage from the PS (don't go more than 18-0-18VAC). By paraleling ic's you can put more current through the load (that's what you need at 2Ohm loads).
I don't see any reasons not to work if you connect 2 or 3 or 4 in paralel (depending on how much power you need).


This is very informative.
http://www.euronet.nl/~mgw/diy/amps/...inclone_1.html

http://diyaudio.com/forums/showthrea...855#post181855
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Old 31st January 2004, 05:37 AM   #3
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I think 2-4 LM3886 will work just fine depending of needed power.
http://www.national.com/appinfo/audi...gn_Guide13.xls
http://www.national.com/appinfo/audi...sign_Guide.pdf
http://www.national.com/an/AN/AN-1192.pdf
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Old 31st January 2004, 06:13 AM   #4
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Matttcattt you must start in one end: Not bridged => max voltage => Gives this voltage enough power in 2 ohms? If yes, estimate how many LM3886 you must use in parallel. If no, you can bridge connect, gives you the double voltage, estimate how many LM3886 you must have in parallel.

If you want rather much power maybe it's better with an discrete built amp?
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Old 31st January 2004, 08:10 AM   #5
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Default Re: Re: Bridged and Parralleled to drive two ohm load

Quote:
Originally posted by GregGC



You'd need to bridge them if you are driving loads more than 8Ohms load or you have limited PS voltage (car amps). That way you have double the amount of voltage across the load. In your case look at paraleling only. I don't see a reason to bridge them. You have enough voltage from the PS (don't go more than 18-0-18VAC). By paraleling ic's you can put more current through the load (that's what you need at 2Ohm loads).
I don't see any reasons not to work if you connect 2 or 3 or 4 in paralel (depending on how much power you need).


This is very informative.
http://www.euronet.nl/~mgw/diy/amps/...inclone_1.html

http://diyaudio.com/forums/showthrea...855#post181855
Thanks

Quote:
Originally posted by peranders
I think 2-4 LM3886 will work just fine depending of needed power.
http://www.national.com/appinfo/audi...gn_Guide13.xls
http://www.national.com/appinfo/audi...sign_Guide.pdf
http://www.national.com/an/AN/AN-1192.pdf

Quote:
Originally posted by peranders
Matttcattt you must start in one end: Not bridged => max voltage => Gives this voltage enough power in 2 ohms? If yes, estimate how many LM3886 you must use in parallel. If no, you can bridge connect, gives you the double voltage, estimate how many LM3886 you must have in parallel.

If you want rather much power maybe it's better with an discrete built amp?
This is purely theoreticle.
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Old 31st January 2004, 08:43 AM   #6
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rowland uses 6 lm3886 in parallel and they are bridged against 6 others - 12 in total with a 1200va sm supply (monoblock)......and his cooling arrangement isn't that big - i suppose it works or it wouldn't be on the marked, and the price is as high as the competition......
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Old 31st January 2004, 01:20 PM   #7
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Quote:
Originally posted by tbla
rowland uses 6 lm3886 in parallel and they are bridged against 6 others - 12 in total with a 1200va sm supply (monoblock)......and his cooling arrangement isn't that big - i suppose it works or it wouldn't be on the marked, and the price is as high as the competition......
what is the output of this monster?
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Old 31st January 2004, 01:35 PM   #8
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Default Re: Re: Re: Bridged and Parralleled to drive two ohm load

Quote:
Originally posted by Matttcattt
This is purely theoreticle.
Indeed, but if you can't do a theoretical calculation, it's much harder to know what you can achieve.

42 volt is max => 35-37 V peak out => gives you 342 W at 2 ohms.... max.

One bridged pair can take 8 ohms load => you may need 3-4 pairs = 6-8 LM3886.

If you really need 8 pcs of LM3886 you can make a really expensive discrete amp for the same price.
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Old 31st January 2004, 01:57 PM   #9
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http://www.jeffrowland.com/Model%2012%20Page.htm
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Old 31st January 2004, 05:47 PM   #10
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Default Re: Re: Re: Re: Bridged and Parralleled to drive two ohm load

Quote:
Originally posted by peranders

Indeed, but if you can't do a theoretical calculation, it's much harder to know what you can achieve.

42 volt is max => 35-37 V peak out => gives you 342 W at 2 ohms.... max.

One bridged pair can take 8 ohms load => you may need 3-4 pairs = 6-8 LM3886.

If you really need 8 pcs of LM3886 you can make a really expensive discrete amp for the same price.
i am using OPA549, not LM3875 or ML3886. I have 6 OPA549, and i was thinking of usign these to create a prototype (if i ever try this idea). 342W, wow, even 200W would be impresive.

Quote:
Originally posted by tbla
http://www.jeffrowland.com/Model%2012%20Page.htm
cool
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