I was pondering about this the other day, although the 0R33 or whatever value is chosen, are needed in amps especially when multiple devices are paralleled, these add resistance in series with the voice coil, but audiophiles want this top notch super loudspeaker cable to be used, to ensure the signal is not degraded. The emitter resistors add a similar resistance that a length of bell wire would be to the speakers!
I understand your point there! it is like some hifi amps use fuses in the outputs to protect speakers, and if you see those fuses...they are just a piece of thin wire encapsulated in a small glass cylinder . and people use those $$$$$ thick speakers wires after those cheap fuses lol. But again, I rather not touch that point since there are many people that have closed minds.
As You seems to now what they are there for, I really don't understand Your question.
There is a kind of misunderstanding this about a resistance is added betwenen the amp and speaker coil.
As the output impedance is determined more of the total design of the amplifier, You will get absolutely no difference if You try to remove them and replace them wint a piece of wire. The only effect You get i a less stable amplifier and a possible chrash of the amp.
There is a kind of misunderstanding this about a resistance is added betwenen the amp and speaker coil.
As the output impedance is determined more of the total design of the amplifier, You will get absolutely no difference if You try to remove them and replace them wint a piece of wire. The only effect You get i a less stable amplifier and a possible chrash of the amp.
I understand your point there! it is like some hifi amps use fuses in the outputs
to protect speakers, and if you see those fuses...they are just a piece of thin
wire encapsulated in a small glass cylinder . and people use those $$$$$ thick
speakers wires after those cheap fuses lol. But again, I rather not touch that
point since there are many people that have closed minds.
Hi,
The intelligent designers put the fuses inside the feedback loop, usually
bypassed by about 1Kohm, it avoids the inevitable thermal distortion.
rgds, sreten.
The intelligent designers put NO FUSES! an example is the famous Bryston B60
they are very well build, they warranty their amps for 20 years. The sound is excellent too.I guess all is to the designers. I remember long time ago a friend had an amp that was a diy, and it had only one fuse for the AC primaries lines (on chassis). one time He took the speakers out and shorted the speakers wires while it was playing very loud music after that He put speakers back and kept playing music like nothing happen. it played beautiful music, He did not want to show me the guts of it. I have never seen this before!!!
PS: The amp did not have any kind of protection, well that what He told me that time.
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Not quite: they determine the amplifier's behavior in the all-important crossover region, and if non-linearities occur, they can only be reduced by the FB, not eliminated.
In principle, their value should allow for a drop of Vt at the quiescent current, but in practice the lower they are, the better (from a linearity perspective).
Pushing this reasoning to its end means removing them completely: it is a cheap way of gaining performances. There are some notable examples of such amplifiers: http://www.diyaudio.com/forums/soli...mplifier-dx-amp-my-amplifier.html#post1134016
But doing that is bartering with the devil, and there is always a risk for a thermal sequence of events to trigger a destructive thermal runaway
It is not quite as simple as that. It depends on output stage topology (e.g. Darlington, CFP) too.Elvee said:
The resistors are there for a purpose. Many people seem to think they are just a safety feature but they play a role in obtaining a clean(ish) handover in the crossover region, especially for CFP. They affect the output impedance of the amp, but not directly as NFB and driver source impedance have big effects too.
I don't quite understand the OP's question, unless he enjoys sending people off on wild goose chases.
Let me add a bit to that ..
--there is amplifiers designed to operate without emitter resistors few but exist .
--If audiophile can accept a class AB amplifier as audiophile then we can also accept the first paragraph
--Then again if class AB or highly biased AB can be accepted as audiophile then this cannot be done with more than a pair of transistors since the extra pair (s) will never operate close to the first so there goes the audiophile approach
by the above logic none BTL can be audiophile and no amplifier with more than one pair of transistors can be really audiophile ..
Real audiophile could be an sziklai pair where actually small quick drivers provide the voltage while parallel ( pair) big outputs will provide the current according to the drivers
Still we all know that this is nightmare to stabilize
Kind regards
sakis
--there is amplifiers designed to operate without emitter resistors few but exist .
--If audiophile can accept a class AB amplifier as audiophile then we can also accept the first paragraph
--Then again if class AB or highly biased AB can be accepted as audiophile then this cannot be done with more than a pair of transistors since the extra pair (s) will never operate close to the first so there goes the audiophile approach
by the above logic none BTL can be audiophile and no amplifier with more than one pair of transistors can be really audiophile ..
Real audiophile could be an sziklai pair where actually small quick drivers provide the voltage while parallel ( pair) big outputs will provide the current according to the drivers
Still we all know that this is nightmare to stabilize
Kind regards
sakis
still i think that for a very long time class AB didn't do much from design aspects we have seen many variations of the same thing with a bit here and a bit there .
I still think that there should be more juice in the sziklai amps but people with better theoretical approach than me should try to squeeze it out ...
I still think that there should be more juice in the sziklai amps but people with better theoretical approach than me should try to squeeze it out ...
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