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Old 1st July 2010, 09:18 AM   #11
pwan is offline pwan  United Kingdom
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Question Speaker protection from DC?

Quote:
Originally Posted by Nelson Pass View Post
Try 16nf across the 100 ohm feedback resistors
Papa,

One thing that really annoy me to get the answer. I don't see you use speaker protection (from DC) on any Firstwatt commercial amps. How risky is it to have the speaker blow in the long run?
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Old 2nd July 2010, 12:26 AM   #12
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I have never, ever, lost a speaker to amp failure. I did once
lose one to a DC coupled amp which was fed DC...

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Old 2nd July 2010, 12:27 AM   #13
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Quote:
Originally Posted by pwan View Post
I mainly use CD player as source and seems the F5 gain is not sufficient.
Take out one each of the parallel 100 ohm feedback resistors
and the gain will double.

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Old 2nd July 2010, 02:58 PM   #14
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Quote:
Originally Posted by Nelson Pass View Post
I have never, ever, lost a speaker to amp failure. I did once
lose one to a DC coupled amp which was fed DC...

Bet that got your attention. (Thump) Followed by a choice word or two. Being a human being is wonderful thing.
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Old 3rd July 2010, 03:41 PM   #15
pwan is offline pwan  United Kingdom
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Thanks a lot, Papa.
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Old 3rd July 2010, 06:50 PM   #16
pwan is offline pwan  United Kingdom
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Quote:
Originally Posted by Nelson Pass View Post
Take out one each of the parallel 100 ohm feedback resistors
and the gain will double.

Papa,

That means less NFB. You must have reasons why selects R 50R/10R for NFB rather than 100R/10R which has more gain.

What the price of "Take out one each of the parallel 100 ohm feedback resistors " we have to paid -- more distortion? poor bandwidth?

And the most important, how that impact to the sound?
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Old 3rd July 2010, 09:28 PM   #17
juma is offline juma  Germany
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Quote:
Originally Posted by pwan View Post
...how that impact to the sound?
That should be fairly easy to try...
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Old 4th July 2010, 02:49 PM   #18
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Less feedback will reduce the bandwidth a bit, and does the
job of a small capacitor. Yes, a little more distortion, and less
DF, but I wouldn't think twice about it.

Easy to try....

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Old 5th July 2010, 07:30 AM   #19
pwan is offline pwan  United Kingdom
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I worry about oscillation since don't have oscilator at all.

Other class B/AB amps, oscillation at high freq can be detected by he hot temperature, however, this method cannot be applied. That's why.

I will try it soon.

Thanks Juma. Thanks Papa.
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Old 5th July 2010, 08:17 AM   #20
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May be an AM radio could show them?
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