Do you have any measurements that shows the difference in IMD with x over before and after amplifier. Normally I woulden't consider IMD to be an important parameter in modern amplifiers. I know its disharmonic in nature, but also very low in moderne amplifiers.
But, is it significant enough to be audible? No need to discuss a problem that might not be there, just because it in theory could be an issue. Just like skin effect in cables for LF audio.
but have you tried to compare filter before and after? And how do you now it's IMD you can hear.
I have tried similar things, and I can hear a difference, but I'm not able to say if it's IMD or just less stress on the amps, since there are now two of them.
One other theoretical problem. Even though the amps are identical, they are not necesarally electrically 100% identical, so what bad things can these differences have in the x over region. Is it the difference between amps you now here, and perceive as being better?
Sorry to acts as the devils advocat, but these effects we are discussing are very complex. Speaking for my self, I simply do not know exactly what causes a different perceived sound from the audio system.
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Nice amp, Nice speakers. I keep having to stop myself from buying a PA-5. Of a Forte 5, or...
Please notice the very significant point that was made. The OEM cannot tune his crossover for your room. They tune for what they expect ( if smart) or some ideal chamber ( if they are not smart). DIY has the advantage to better that, be it either passive or active filtering. Choose you direction and report back.
With active crossovers, you don't need impedance compensation. That is one of the main advantages. Amps are voltage devices. (Remember, you still had better put a blocking cap on the tweeter!) With the ML, is it driving a transformer on the top end?
Yes, your output stage is generating distortion. That is why the designer of your amp used so many transistors and something we call feedback. You may like to discuss that with him, I believe he has his own forum here.
I believe your premise here is that there are benefits to isolating the passive crossovers with dedicated amps. Most here would suggest tuning the crossover and use one amp, or go electronic crossover where you have a lot more opportunities to tune for your room. If you find a marked improvement in isolating the amps and passive crossovers, do report what you find.
I would not dismiss IM lightly. In the amp, yes it is very small, but in the speaker it can be very large. Harmonic distortion exciting breakup modes that cause modulation in the audible range. My idea for an ideal system is a hybrid approach. Active crossover but passive notch filters to suppress the breakup of the mid and tweet.
Please notice the very significant point that was made. The OEM cannot tune his crossover for your room. They tune for what they expect ( if smart) or some ideal chamber ( if they are not smart). DIY has the advantage to better that, be it either passive or active filtering. Choose you direction and report back.
With active crossovers, you don't need impedance compensation. That is one of the main advantages. Amps are voltage devices. (Remember, you still had better put a blocking cap on the tweeter!) With the ML, is it driving a transformer on the top end?
Yes, your output stage is generating distortion. That is why the designer of your amp used so many transistors and something we call feedback. You may like to discuss that with him, I believe he has his own forum here.
I believe your premise here is that there are benefits to isolating the passive crossovers with dedicated amps. Most here would suggest tuning the crossover and use one amp, or go electronic crossover where you have a lot more opportunities to tune for your room. If you find a marked improvement in isolating the amps and passive crossovers, do report what you find.
I would not dismiss IM lightly. In the amp, yes it is very small, but in the speaker it can be very large. Harmonic distortion exciting breakup modes that cause modulation in the audible range. My idea for an ideal system is a hybrid approach. Active crossover but passive notch filters to suppress the breakup of the mid and tweet.
But, your argument is not technical. It's backed up by measurements. It's just an idea you have, it might be correct, but it might as well not be.
There are simply to many unknown factors here, and you are justing pointing one of them out.
It's not just "there are now two of them".
Each amplifier is connected to a filter with a speaker driver on the far end.
That filter is either a low pass feeding the bass/mid or a high pass feeding the treble, for 2way bi-amping.
The impedance of that intervening filter is low in the passband and thus allows the amplifier to "see" the driver impedance.
Out of the passband the filter presents a higher impedance and very much higher when more than a couple of octaves away from the crossover frequency. The amplifiers thus see an average load impedance that is much higher than if driving the "whole crossover". It's that easier load that allows the amplifier to perform better.
How does DougL come up with?
Looks like he did not think about what he was concluding.
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Being a non expert, I would suggest that the "sound difference" could be due to some, or a lot of effects. I could certainly NOT conclude that the effect is down to reduction in IM !!!!!
A good passive crossover will minimise the risk of saturation in the inductors. Saturation should be a non issue.
Real inductors have parasitics. The "speaker designer" will use these parasitics to tune the final sound. Similarly he/she will use the capacitor parasitics to tune the sound.
A good speaker designer will specify the components so that the sound suits the customers and make money for the manufacturer. That "goodness" in designing does not always equate to high accuracy.
Real inductors have parasitics. The "speaker designer" will use these parasitics to tune the final sound. Similarly he/she will use the capacitor parasitics to tune the sound.
A good speaker designer will specify the components so that the sound suits the customers and make money for the manufacturer. That "goodness" in designing does not always equate to high accuracy.
A cross over in a good speaker like Martin Logan DOES not saturate cause it is an air inductance.
I have to noticde that you prefer an active filter before the amp with all the problems an active filter generate. I guiest, seeing your postings, that you dont know this matter. How will you make a good active filter???? lets laught.
I have to noticde that you prefer an active filter before the amp with all the problems an active filter generate. I guiest, seeing your postings, that you dont know this matter. How will you make a good active filter???? lets laught.
The laws of physics have not changed. Old does not mean bad. I have a new fancy pneumatic nailer, but I also keep a hammer. I choose the tool for the job. Crossovers are the same thing. Chose the tool that meets the needs. No one right answer.
This is so very true even though Mr liching's approach says otherwise.
Yes let's do that.
liching,
The same transfer function as a stock Martin Logan Sequel can easily be created with an active crossover.
You could also perform impedance correction (if necessary) as well.
This type of "conversion" project has been done multiple times (on various commercial designs) by members of this forum. Do some searching and reading on this forum.
Your initial premise is simply incorrect.
Cheers,
Dave.
The same transfer function as a stock Martin Logan Sequel can easily be created with an active crossover.
You could also perform impedance correction (if necessary) as well.
This type of "conversion" project has been done multiple times (on various commercial designs) by members of this forum. Do some searching and reading on this forum.
Your initial premise is simply incorrect.
Cheers,
Dave.
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