Do chipamps have clipping danger like SS amps?

[spwal]

Hi,

I will be running a 25 wpc chipamp from a patek se kit and am concerned that power may be too low to run my 99Db 8 ohm speakers. The speakers are very nice and i do not want to damage them. As i understand it, they can be damaged if underpowered, even at very low volumes.

please forgive my noobness.

[pinkmouse]

Yes, chip amps do clip. But with 25W and 99dB efficient speakers they will be pretty loud when they do so. But if you are still worried, you could always change the feedback resistor to reduce gain.

[peranders]

Here you can see how see how the clipping look like (my "Gainclone" built by Keld).
http://www.keld.eu/gainclone/test.htm

Notice the 100% clean startup and shutdown behaviour (the first pictures).

[spwal]

thank you for the replies.

was concerned with causing dangerous distortion on strong transients. i was under the impression that this could occur regardless of the volume.

I dont ever plan on cranking these speakers to rediculously loud levels.

please tell me if this is something to concern myself with.

thanks

[peranders]

Originally posted by spwal
i was under the impression that this could occur regardless of the volume.

Can you explain that?

Transients are signals with a certain frequency spectrum. If you have a CD as a source frequencies higher than 22 kHz won't ever come out of the CD player (if the filtering is good).

[spwal]

hi,

i guess what i ment to say was sudden bursts of complex music, i guess it doesnt matter as long as the amp isnt turned up that loud and pushed beyond its limits. thank you for your help

[Steve Eddy]

Originally posted by peranders
Notice the 100% clean startup and shutdown behaviour (the first pictures).

Heheh. That's pretty cool plotting the + and - supply rails along with the output like that.

se

[Peter Daniel]

Originally posted by spwal
I will be running a 25 wpc chipamp from a patek se kit and am concerned that power may be too low to run my 99Db 8 ohm speakers. The speakers are very nice and i do not want to damage them. As i understand it, they can be damaged if underpowered, even at very low volumes.

I was using $800/pc FAL drivers with bridged Patek amp for some time. The drivers impedance was 4 ohm, so each amp was working with 2 ohm impedance. At normal levels it was fine, but at higher volume, on material with substantial bass content, the clipping was unavoidable and quite severe. However neither the amp, nor drivers have been damaged.

Presently, with 100db, 8 ohm Fertins, there is no clipping at all. This is still 4 ohm load per amp, so you should be safe with your speakers.

Anybody tried FAL drivers?

[spwal]

There is no one i would like to hear this from more than the man himself. thanks peter!

[lineup]

Originally posted by spwal
There is no one i would like to hear this from more than the man himself. thanks peter!

different chips has got different Overload protection.
The national overture series LM3875 LM3886 and LM4780
has got SPiKe protection

This means that at very high currents PEAKs will be blocked.
The level at which this protection limits, is a bit different for different chips.
I do not know if LM1875 has got this, too.
But this is for a bit lower power output than the others.

LM3886 / LM4780 allows more current output than LM3875, before this limit comes into action.
This makes LM3886 better suited for 4 Ohm speakers at higher powers.

The performance of the LM3886, utilizing its
Self Peak Instantaneous Temperature (°Ke) (SPiKe™) protection circuitry,
puts it in a class above discrete and hybrid amplifiers
by providing an inherently, dynamically protected Safe Operating Area (SOA).
SPiKe protection means that these
parts are completely safeguarded at the output against
- overvoltage,
- undervoltage,
- overloads,
- including shorts to the supplies,
- thermal runaway, and
- instantaneous temperature peaks.

For further information, I would recommend:
Read about the SPiKe details in datasheet of LM3886:
http://www.national.com/ds.cgi/LM/LM3886.pdf



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