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Old 24th April 2003, 03:00 PM   #1
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Default questions about gainclones

i want to try bridging and parrelleling gainclones, which should i try first and what circuit/s should i use?

what chips should i use when bridging?

in theory can the input capacitor be any value? maplin have some nice 8uf ones for 5 and 15uf for 10

i am ordering some chips: OPA548T, OPA541AM, OPA541AP, OPA549S and OPA549T, what other chips should i try (not just the gainclone chip itself, balancing ones for bridging)?

i ordered some OPA549 from Texas Instroments a while ago (a month+) and i havent recieved them, are they really being bought up that fast that they stay out of stock?
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Old 24th April 2003, 03:27 PM   #2
Emilio is offline Emilio  Spain
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Talking NSC BPA-200

Hello,

Regarding the circuit and parts list, you should read National Semiconductor Application Note BPA-200 in http://www.national.com/appinfo/audi...ation_Note.pdf

It has everything you wanted to know but were afraid to ask...

Emilio
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Old 24th April 2003, 04:51 PM   #3
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is this the simplest circuit for bridging and parelleling? are the 1kR input resistors necesary? are the 0.1R resistors between the outputs and the speaker necesary? is the LF412CP the correct opamp for U5?
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Old 24th April 2003, 04:54 PM   #4
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my power supply that i am building is using this circuit, is there any need to use the circuit in my next post for a gainclone? i am no audiophile
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Old 24th April 2003, 04:59 PM   #5
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Old 27th April 2003, 09:57 PM   #6
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answers to my questions?
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Old 30th April 2003, 06:01 PM   #7
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i really would like some answers, or atleast comments
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Old 30th April 2003, 06:09 PM   #8
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Resistors are necesary. U5 can be any unity gain stable opamp.
(make sure it is)

Second supply looks better. It's got some nice bleeders.
It also has snubbing caps around the bridge which help little.
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Old 30th April 2003, 06:11 PM   #9
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I'll bite..............

The 5k resistors are to bleed the 33KuF caps when the Mains power is shut Off - this would be a "normal" type of safety precaution.

22nf - There has been a very good input by a person whose name I forgot (Please excuse me for that) about "Snubber" caps and how their use may actually make it worse. I wouldn't use them, although I WOULD use a MUR or other Fast/Soft rectifier Diode.

If you just want to try it, you just have to build it. Then make ONE change at a time to see if you like it better.
johnm
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Old 30th April 2003, 08:34 PM   #10
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thanks for the answers

are the 0.1R resistors really necessary? what do they do?
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