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Old 16th March 2013, 06:08 PM   #11
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Quote:
Originally Posted by DF96 View Post
I suggest the OP makes himself a cup of coffee (or whatever beverage suits him) and then sits down to read the 'reservoir cap size' thread. All his questions will be answered, in more detail than he probably wants at this stage.
The length of that thread, and its occasional meanderings, shows that the answers are not quite as simple as some people think but not as esoteric as others like to imagine.
It all boils down to a ripple calculation. No magic needed, just a calculator or one of gootee's spreadsheets.
A very welcome suggestion. Thank you
I start reading and hope to understand something
Kind regards
gino
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Old 16th March 2013, 08:04 PM   #12
JMFahey is offline JMFahey  Argentina
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Agree with the above suggestions and add:
the first and most obvious limiting we find is, of course, reaching the voltage rails.
Then DF96 and Tom Gootee speak about what we find when we reach there.
There's things worse than a clipped squarewave .
The ripple will appear *in full* into the speaker, because the transistor (or tube) , being saturated, behaves like a piece of wire , connecting the speaker to the rail and whatever's there.
And thirdly, we have the amplifier current capability.
Short protection usually takes the form of current limiting, which if "too loose" protects little and if "too stiff" , yes, protects better, but often sounds screechy or worse.
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Old 17th March 2013, 08:53 PM   #13
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Originally Posted by JMFahey View Post
Agree with the above suggestions and add:
the first and most obvious limiting we find is, of course, reaching the voltage rails.
Then DF96 and Tom Gootee speak about what we find when we reach there.
There's things worse than a clipped squarewave .
The ripple will appear *in full* into the speaker, because the transistor (or tube) , being saturated, behaves like a piece of wire , connecting the speaker to the rail and whatever's there.
And thirdly, we have the amplifier current capability.
Short protection usually takes the form of current limiting, which if "too loose" protects little and if "too stiff" , yes, protects better, but often sounds screechy or worse
Thank you very much indeed
Personally and most of the time i listen to music at low level not to annoy neighbors
But even a low level with amps with higher current delivery the result is more complete, with all the audio range on the same level and in the end the result is much more enjoyable
The weaker amps give more mids and highs but fail on the low end, even if i listen to 1 W or so
This is quite strange but also quite evident
Now that i understand that some amps are very limited in current it would be nice that this max output current would show up in the specifications.
I do not think that the limits are in the output devices
For instance i see for the chip LM3886 a max output current of 7A
This is quite a lot indeed (i have just checked. I did not imagine a so high value indeed for a power chip)
But to output this current i think a substantial PS is mandatory
150 W types transistors are very cheap indeed
In my cheap c352 i found these

Click the image to open in full size.

Silly that i am i bought it thinking to have quite a current
Of course is not the case. Exceptional output bjts alone are not enough
The real limitation is in the power supply and then they must put current limiting circuits to protect the weak power supply that is where the costs can increase very easily
Another wrong decision
And there is no space for bigger caps and transformer
Thanks a lot
Regards,
gino
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Old 17th March 2013, 09:10 PM   #14
AndrewT is offline AndrewT  Scotland
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Originally Posted by ginetto61 View Post
............even if i listen to 1 W or so
.........
I don't count that as low level music.
10mW into 87dB speakers is maybe low level.
100mW to 1W is normal level into similar speakers.
High level would be 2W to 20W.
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Old 17th March 2013, 09:49 PM   #15
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Originally Posted by AndrewT View Post
I don't count that as low level music.
10mW into 87dB speakers is maybe low level.
100mW to 1W is normal level into similar speakers.
High level would be 2W to 20W.
i said 1 W but maybe is really less as you say
I did not measure actually
Regards,
gino
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