Good morning (French time),

I am a JBL listener since years (4311 - 4320 - 4333 and 4355) and I am reading this forum since several months now.

I also had several home made ALTEC speakers made of 411-8A woofer, 511 or 811 horns with a 806-8A driver.

I noticed quite a lot of complaints about lack of this, lack of that, willing to compare the dynamic and sound image of a 4343 / 4355, and so on.

I must say that I am working since 25 years in the amplifier market and I begin to have some knowledge’s about what an amplifier is.

You may not agree with me but I always thought that the quality of an amplifier is not only ascertained by sophisticated laboratory control methods.

One has to hear his performances, the human ear being the best of judges.

A sound is not only built up with technical specifications.

The only numbers I trust in are the signal to noise ratio (> 100 dB), the CMRR if you have a balanced input (> 80 dB) and the peak power!

Other numbers are just useless.

About distortion:

Add the distortion of the speaker, of the room and of your ear and you will be close to 3-4%. In such a case how important is the distortion of an amplifier? Nuts …

Damping factor:

I am not the author of this theory, but if the damping factor is > then 17, what ever the number is it has no significant meaning. Never forget that the damping factor is calculated at the “bottom” of the amplifier and do not include the wires and the impedance of the speaker at low frequencies. As a bass reflex speaker has a bigger impedance at low frequencies, the damping factor will raise immediately.

When an amplifier manufacturer argue that his amplifier has an enormous damping factor at 8 ohms and this is very good for bass restitution, and his amplifier handles easily a 2 ohm impedance, just divide by 4 this damping factor …

This is a 100% commercial number.

All those numbers and others do not make the sound quality!

There are things everybody ignores as I do, and they make an amplifier sound good!

The use of one brand of capacitors, the use of a type of capacitors, such quality of resistors, and so on is the basis of known things in the audiophile area.

After that, changing one component for an other can make an amplifier sound great, better or worse!

Let me give you several examples:

Change the bridge of your amplifier and the bass response can change radically; I did it just by changing a 20A bridge for 25A bridge from the same manufacturer and same bridge family (as I use a twin bridge in each channel for a 150W amplifier there is no relation between the needed amperes and what the bridges can deliver).

I made the same with an other brand and other models, it did not work the same.

Removing a limiter circuitry will enhance the micro information in the mids and high frequencies,

Changing an input potentiometer from one brand to an other, even if this potentiometer is set at 10 (wide open) it will change the tonality of your amplifier,

Since a year time that I now have the 4355 JBL speakers I made so many changes on my amplifier (same schematic, AB class, quasi complementary bipolar output transistors) I have now (and the job is not over and never will be) a new sound system:

I have all the low bass I was looking for,
I have more low mids,
There is no more agressivity (is it the good word) in the mids,
I have much more information in all the frequencies,
The high are also dam smooth and even more precise.

All what I did was to got the good settings in my amplifier.

This is perhaps the beginning of a long thread and I think it will be helpful for all of us and I hope I did not bore you too much with this message!