Subwoofers in Series?
11-04-2006, 07:22 AM
#21
The intent is to have multiple drivers in series/parallel configurations that add up to a reasonable 4ohmish load to the amp, not some wild 16 ohm etc load.
I have 2 more observation:
1: you see many VERY high end home audio speakers with 4 woofers....I assume these are wired in series/parallel with no concern about series connections. This would also seem to be counter to the JL advice.
2: Speaker box programs such as WinISD allow you to select the # of woofers with no mention or warning about series connections.
So for me, I have not made a definitive conclusion yet. I have been hobbing in electronics and speakers since I was a teenager and this is the first time I see any reference to speakers in series as being bad. So I am skeptical about the claim.
All the statements about back emf modulating the other woofer etc. is conjecture at this point because I have not seen ANY theoretical proof or measurements to back it up! AND no one else making a post on this thread has done so either....
Speakers are complex electromechanical systems and my feeling is that few, if none, of us on this board have the knowledge and experience to give the answer....
So my search for the TRUTH continues... That is what engineers do!
I am looking for a scientifically based research that looks something like this:
1: we have noticed unusual response from woofers in series.
2: we made some measurments and noticed increased intermodulation distortion.
3: we looked at TS parameters and came up with some equations and mathematical simulations that explains and predicts why 2 slightly different (just manufacturing tolerances) woofers in series cause this distortion.
3: we made many more measurements of different kinds of woofers in series and the measuremnts back up the theory.
4: we conclude that it is not good to put woofers in series because of this intermodulaiton effect.
The above 4 statements are called the scientific method. It is the Research part of R&D.
I have 2 more observation:
1: you see many VERY high end home audio speakers with 4 woofers....I assume these are wired in series/parallel with no concern about series connections. This would also seem to be counter to the JL advice.
2: Speaker box programs such as WinISD allow you to select the # of woofers with no mention or warning about series connections.
So for me, I have not made a definitive conclusion yet. I have been hobbing in electronics and speakers since I was a teenager and this is the first time I see any reference to speakers in series as being bad. So I am skeptical about the claim.
All the statements about back emf modulating the other woofer etc. is conjecture at this point because I have not seen ANY theoretical proof or measurements to back it up! AND no one else making a post on this thread has done so either....
Speakers are complex electromechanical systems and my feeling is that few, if none, of us on this board have the knowledge and experience to give the answer....
So my search for the TRUTH continues... That is what engineers do!
I am looking for a scientifically based research that looks something like this:
1: we have noticed unusual response from woofers in series.
2: we made some measurments and noticed increased intermodulation distortion.
3: we looked at TS parameters and came up with some equations and mathematical simulations that explains and predicts why 2 slightly different (just manufacturing tolerances) woofers in series cause this distortion.
3: we made many more measurements of different kinds of woofers in series and the measuremnts back up the theory.
4: we conclude that it is not good to put woofers in series because of this intermodulaiton effect.
The above 4 statements are called the scientific method. It is the Research part of R&D.
11-04-2006, 10:33 AM
#22
Administrator
Join Date: Feb 2006
Posts: 16,855
^ So do it. 
As for back EMF and modulation, it is not conjecture, it is fact. Proving it exists is as simple as wiring a pair of speakers in series and pushing on the cone of one and watching the cone of the other move.
How audible it is or how much it affects the system is another thing entirely.
As for back EMF and modulation, it is not conjecture, it is fact. Proving it exists is as simple as wiring a pair of speakers in series and pushing on the cone of one and watching the cone of the other move.
How audible it is or how much it affects the system is another thing entirely.
11-04-2006, 02:02 PM
#23
there are alot of technical terms being thrown around that don't necassarilly have anything to do with this topic...... (for starters damping factor and intermodular distortion are non issues) To boot pushing on the cone of one sub to make the others move is not a good example of what is going on IMO..... as I stated the electrical signal between two coils in series must be exactly the same............ and that is of consequence to the argument that back emf somehow 'drives' the other sub.... (in reality the subs simply influence each other)
If you want to test the effects zoomer, Id recommend looking at the behavior of two completely different DVC drivers (with wildly different T/S) to gain an understanding of what can happen..... same coil series subs parallel versus same coils parallel subs series.... for the same load....
As pointed out to me years ago...... you are going to get 1/2 a dozen of one and six of the other.......
to say one situation is better then the other is meer conjecture......
If you want to test the effects zoomer, Id recommend looking at the behavior of two completely different DVC drivers (with wildly different T/S) to gain an understanding of what can happen..... same coil series subs parallel versus same coils parallel subs series.... for the same load....
As pointed out to me years ago...... you are going to get 1/2 a dozen of one and six of the other.......
to say one situation is better then the other is meer conjecture......
Last edited by Haunz; 11-04-2006 at 02:18 PM.
11-04-2006, 02:36 PM
#24
Originally Posted by Haunz
there are alot of technical terms being thrown around that don't necassarilly have anything to do with this topic...... (for starters damping factor and intermodular distortion are non issues) To boot pushing on the cone of one sub to make the others move is not a good example of what is going on IMO..... as I stated the electrical signal between two coils in series must be exactly the same............ and that is of consequence to the argument that back emf somehow 'drives' the other sub.... (in reality the subs simply influence each other)
If you want to test the effects zoomer, Id recommend looking at the behavior of two completely different DVC drivers (with wildly different T/S) to gain an understanding of what can happen..... same coil series subs parallel versus same coils parallel subs series.... for the same load....
As pointed out to me years ago...... you are going to get 1/2 a dozen of one and six of the other.......
to say one situation is better then the other is meer conjecture......
If you want to test the effects zoomer, Id recommend looking at the behavior of two completely different DVC drivers (with wildly different T/S) to gain an understanding of what can happen..... same coil series subs parallel versus same coils parallel subs series.... for the same load....
As pointed out to me years ago...... you are going to get 1/2 a dozen of one and six of the other.......
to say one situation is better then the other is meer conjecture......
The question was why JL recomends not to put 2 subs in series. There have been comments about back emf, modulation distortion, too high L load for the amp etc. The question has not been answered. I suggest everyone refrain from further post until they have a well researched answer. I would be happy to discuss your last statement in private chat.
11-04-2006, 03:19 PM
#25
^ I already know the answer.....
The reality of the situation is that there are going to be trade off's either way........... and one setup is not necassarilly going to be better then the other..........
Ideally the drivers will be indentical anyway... and there will be no difference either way.......
a simple measure of fs will usually reveal inconsistancies between drivers..... and as recently stated by a prominent audio guru over on carsound....... unless you know for sure, multiple drivers should be avoided all together..............
The reality of the situation is that there are going to be trade off's either way........... and one setup is not necassarilly going to be better then the other..........
Ideally the drivers will be indentical anyway... and there will be no difference either way.......
a simple measure of fs will usually reveal inconsistancies between drivers..... and as recently stated by a prominent audio guru over on carsound....... unless you know for sure, multiple drivers should be avoided all together..............
11-04-2006, 03:29 PM
#26
Originally Posted by Haunz
^ I already know the answer.....
unless you know for sure, multiple drivers should be avoided all together..............
unless you know for sure, multiple drivers should be avoided all together..............
This seems a little impractical. Obviously this is the ideal method but what about for those who rather not run seperate subs and amps to have a multiple driver set up?
Originally Posted by Haunz
The reality of the situation is that there are going to be trade off's either way........... and one setup is not necassarilly going to be better then the other
11-04-2006, 03:32 PM
#27
the 'ideal method' is either identical drivers or one driver only...........
'distortion' (edit: intermodular or harmonic) has nothing to do with anything.... think group delay and differences in phase.....
'distortion' (edit: intermodular or harmonic) has nothing to do with anything.... think group delay and differences in phase.....
Last edited by Haunz; 11-04-2006 at 03:37 PM.
11-04-2006, 03:37 PM
#28
What is identical? Because no two drivers will ever be exactly the same right? So is it ok to wire drivers in series if they are the same model as the others? For instance, if I had three drivers which were manufactured in succession, how bad would the phase or group delay be if they were wired series? Thanks for the insight Hanuz!
11-04-2006, 05:31 PM
#30
Originally Posted by zoomer
guys, you are talking in circles, and no one is backing up any of their statements with proof.
I am waiting to get some info first.
I am waiting to get some info first.
