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woofer wiring confusion


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DYohn 
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Joined: April 22, 2003
Location: Arizona, United States
Posted: May 03, 2011 at 10:30 AM / IP Logged  
ac0j wrote:

thats why I said "for me personally"   it is true that the amp sees the final load in ohms, so thats one thing.  I have found that when I connect more than four voice coils to one Mono block amp (for the sake of discussion)  things tend to start sounding "sluggish"  I think it is due to the multiple voice coils actually counter acting against each other.  This is most noticable when you use different types of woofers in the same circut.  Some woofers react a little faster to the same signal as another woofer, that millisecond of lag between the voicecoils actually acts like a brake on the others.   I am speaking about what I percieve after having done these types of installs over the past 28 years.  Others may not notice it, or maybe never compared the differences in trying multiple woofers several ways in the same car. Power disapates in a voicecoil as well, the more voicecoils, the more power needed & the more power lost.

If you wire two subs together with no amp, push in on the cone of one the other wooder  reacts.   By moving the voice coil of a woofer manually, you can even light an led with nothing more than the voice coil itself. I think it is these characteristics that cause what I hear with multiple woofers on the same amp. Its that mirco second per every cycle that things are out of phase.

The "sluggish" sound you describe has nothing to do with the electrical loading on the amplifier, it is most likely due to timing errors created by multiple woofers reproducing the same frequency from multiple locations.  As far as power is concerned, of course driving multiple voice coils means the available power is distributed among them (Kirchhoff's Law) but that has nothing to do with how it sounds.  I am not sure I understand what point you are trying to make in your second paragraph.  A coil of wire being moved through a magnetic field will generate current flow... yes this is a fact.  What does that have to do with the topic of driving multiple woofers?

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ac0j 
Copper - Posts: 121
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Joined: January 27, 2006
Location: United States
Posted: May 03, 2011 at 1:08 PM / IP Logged  
DYohn wrote:
ac0j wrote:

thats why I said "for me personally"   it is true that the amp sees the final load in ohms, so thats one thing.  I have found that when I connect more than four voice coils to one Mono block amp (for the sake of discussion)  things tend to start sounding "sluggish"  I think it is due to the multiple voice coils actually counter acting against each other.  This is most noticable when you use different types of woofers in the same circut.  Some woofers react a little faster to the same signal as another woofer, that millisecond of lag between the voicecoils actually acts like a brake on the others.   I am speaking about what I percieve after having done these types of installs over the past 28 years.  Others may not notice it, or maybe never compared the differences in trying multiple woofers several ways in the same car. Power disapates in a voicecoil as well, the more voicecoils, the more power needed & the more power lost.

If you wire two subs together with no amp, push in on the cone of one the other wooder  reacts.   By moving the voice coil of a woofer manually, you can even light an led with nothing more than the voice coil itself. I think it is these characteristics that cause what I hear with multiple woofers on the same amp. Its that mirco second per every cycle that things are out of phase.

The "sluggish" sound you describe has nothing to do with the electrical loading on the amplifier, it is most likely due to timing errors created by multiple woofers reproducing the same frequency from multiple locations.  As far as power is concerned, of course driving multiple voice coils means the available power is distributed among them (Kirchhoff's Law) but that has nothing to do with how it sounds.  I am not sure I understand what point you are trying to make in your second paragraph.  A coil of wire being moved through a magnetic field will generate current flow... yes this is a fact.  What does that have to do with the topic of driving multiple woofers?

I will be satisfied to agree to disagree.  I just posted my opinion, everyone is entitled to theirs.  I am just thinking the "current flow" is a factor, and one voice coil laging behind another on the same amp Does have an effect all be it , it is minimal.

Hook 20 4 ohm woofers to one  100 watt amp and tell me that has no effect on the sound quality.

DYohn 
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Joined: April 22, 2003
Location: Arizona, United States
Posted: May 03, 2011 at 3:08 PM / IP Logged  
ac0j wrote:
I will be satisfied to agree to disagree.  I just posted my opinion, everyone is entitled to theirs.  I am just thinking the "current flow" is a factor, and one voice coil laging behind another on the same amp Does have an effect all be it , it is minimal.

Hook 20 4 ohm woofers to one  100 watt amp and tell me that has no effect on the sound quality.

Opinion is fine unless it conflicts with science, then it is simply wrong.  :)  Since electrical current moves at approximately 80% the speed of light it is impossible for there to be any noticeable time lag due to flow through multiple voice coils... unless you're using several thousand miles of wire between the coils.  Assuming the amplifier can handle the net impedance created, there is no effect on electrical performance in either an amp or in woofer voice coils that can be caused by driving multiple woofers, except of course due to power distribution.  You can connect 20 4-ohm woofers to a single 100 watt amp and it will operate just fine and sound just fine.  It will operate at a fairly low level, of course (5 watts to each woofer in an ideal situation) but that is completely different from if it is possible to operate that way.

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ac0j 
Copper - Posts: 121
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Joined: January 27, 2006
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Posted: May 03, 2011 at 8:35 PM / IP Logged  

I dont disagree with the sceince.  I am stateing my opinion based on Practice, not theory. I disagree with the 20 woofers at 5 watts each sounding OK, YES they will make sound, No they wont hurt the amp. But  from doing multiple subs on one amp MANY times, I notice a severe lack of performance when more than 4 are connected.   It doesnt take a thousand miles of wire to have loss in an AC current. Loss will occur at lengths lower than 100 feet.  How many feet of wire is wound around 20 voice coils?  If you know a way to not have loss in a wire even one thousand miles long, I am sure Power companies would like to hear about it!

I NEVER said you couldnt put more than 4, I said I dont like to do it.  But If you are more about quanity than quality,  you can do what ever you want.  I thought The OP was trying to improve a system by adding another woofer, In his case, using what he described, It would be a backwards move.

stevdart 
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Posted: May 03, 2011 at 10:02 PM / IP Logged  

ac0j, the OP was correct in his assertion that the two like woofers were each getting 25% of the power, and that the odd sub was receiving the other 50%.  That is all this thread is about.  "I will be satisfied to agree to disagree." and "I dont disagree with the sceince." are nonsense replies that nobody on this forum appreciates. 

If you don't understand the subject, think about your response before submitting replies.   After a while, you will likely become a good contributor to this forum.  :)

Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.
ac0j 
Copper - Posts: 121
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Posted: May 03, 2011 at 10:41 PM / IP Logged  

Sorry the OP turned into something else.  I get it now, NO Personal opinions allowed, UNLESS proved with ohms law. woofer wiring confusion - Page 2 - Last Post -- posted image.  LOL!

AND now I know who speaks for everyone here.   I will try to be less annoying.  FYI, I dont post here much, but I am NO NOOB!  I have been on this forum on my current name for 5 years, a couple years before that? under a different name that I have now forgotten.  I have been working for the same stereo shop for 28 years. And 5 years more in a stereo shop before this one.  I have been an installer since I graduated from High school in 1981, I was installing before you could get a cd player for the car, and before there was subs in cars,  I got MECP certified in all levels in the first year each level wast offered. I get factory training from every brand we carry every year.

SO My Question to you, who knows what everyone here "appreciates", is..... When am I qualified to give answers or opinions?                                                                       This is a serious question, not meant to start a problem. 

 Do I need a higher post count?  where is the thread I can post random thoughts and boost my post  count and become relevant?

I was just trying to help.

ac0j 
Copper - Posts: 121
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Joined: January 27, 2006
Location: United States
Posted: May 03, 2011 at 10:46 PM / IP Logged  
ac0j wrote:

Sorry the OP turned into something else.  I get it now, NO Personal opinions allowed, UNLESS proved with ohms law. woofer wiring confusion - Page 2 - Last Post -- posted image.  LOL!

AND now I know who speaks for everyone here.   I will try to be less annoying.  FYI, I dont post here much, but I am NO NOOB!  I have been on this forum on my current name for 5 years, a couple years before that? under a different name that I have now forgotten.  I have been working for the same stereo shop for 28 years. And 5 years more in a stereo shop before this one.  I have been an installer since I graduated from High school in 1981, I was installing before you could get a cd player for the car, and before there was subs in cars,  I got MECP certified in all levels in the first year each level wast offered. I get factory training from every brand we carry every year.

SO My Question to you, who knows what everyone here "appreciates", is..... When am I qualified to give answers or opinions?                                                                       This is a serious question, not meant to start a problem. 

 Do I need a higher post count?  where is the thread I can post random thoughts and boost my post  count and become relevant?

I was just trying to help.

SORRY cant edit posts!  That should be 25 years at the same shop plus 5 at another.  There was overlapping employment between the 2 for a total of about 28 years But who's splitting hairs?

DYohn 
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Joined: April 22, 2003
Location: Arizona, United States
Posted: May 03, 2011 at 11:07 PM / IP Logged  

No one is questioning your experience.  Just your assertions.  One of the purposes of the12volt forum is to debunk bad information and ensure that installers and novices alike have a safe, fact-based place to discuss their passion about car audio and related fields.

There was nothing annoying about your posts until your last couple.  Please leave the attitude at the door.  Thanks.

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haemphyst 
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Joined: January 19, 2003
Location: Michigan, Bouvet Island
Posted: May 04, 2011 at 8:07 PM / IP Logged  
ac0j...
I see the breakdown in communications as this:
You're intelligent, of this I have no doubt. You're not smart. Please let me finish, I don't want you to think I mean that at completely face value. Smart listens, and is willing to accept things that can be proven. I haven't seen this quality of you, yet. Your age notwithstanding, (I am almost the same age - an '86 grad) listen. I learn something new everyday, because I listen.
There's no denying the above, however, you are certainly playing with fire when you attempt to challenge DYohn to any kind of electrical or acoustic theory war... This is not "defending" DYohn, per se, he needs no defense by me; I've met the man, and if you actually graduated in 81, a mere "few" years before I did, then you are still "a bit" younger than DYohn... (Sorry, Dave.) He has a cirriculum vitae as long as my arm, and has worked with the US Government developing undersea infrasonic communications systems, amongst other (at the time) very "hush hush" electrical and acoustic stuff. Read his (and my) bio(s). A loudspeaker designer from your elementary school days (I promise you this) and possibly one of the smartest guys I've ever had the pleasure of dining at Todai with. (Todai is an all you can eat Asian/American food buffet in the Bay Area, if it matters.) A close personal friend of Dan Wiggins, possibly one of the foremost loudspeaker designing minds of this generation, DYohn knows more about system design than nearly anybody here (<ego booster> He HAS admitted to not understanding Transmission Line theory as well as I do, however... </ego booster>)
The breakdown is not knowing when to just listen. Really.
As stated, electricity travels at .8c in a wire (althought I thought it was closer to .95c) c, the velocity of light, is 186,282 miles per SECOND. That's 983,568,960 feet per second! Electricity therefore, travels at 149,025 miles per second in a wire, or 786,855,168 feet per second. SIX TIMES AROUND THE EARTH (at the equator) IN ONE SECOND!!! We're not discussing losses, here, we're talking a zero-current, charged-to-a-given-potential, wire. (Losses do not affect the speed of the electricity anyway.) If, for example, you had 100, 200-Ohm, 18 inch woofers, connected in parallel, we would have approximately 150 feet of wire to travel through, from the amplifier terminals to the very end woofer. For electricity to travel one foot in a wire, it will take .00000000127 seconds. For that same impuse to travel 150 feet, it would take 0.0000001905 seconds. That's 19.05 PICOSECONDS!!! PICO, baby... 190 ten-thousandths of one millisecond! There is absolutely ZERO way that any dynamic driver cone can EVER react so quickly that you would ever even be able to MEASURE the difference, let alone HEAR the difference in acoustic output impulse. None. It will not ever happen! You are not hearing any acoustic waveform smudging, simply attributable to the number of woofers connected.
Now, this being laid out in hard, fast, scientifically explainable and PROVABLE phrases, I will concede that IF you are indeed hearing acoustic waveform smudging, it is because you are running your voice coils in series-parallel, or even in straight series... This, I will grant you, will increase the inductance within the series portions of the circuits. Inductance can cause "slow" response in a voice coil, and wiring a significant number of them in series could possibly cause a smudging. However, (and ignoring the resistance portion of a dynamic loudspeaker for the moment) if you have in parallel branches, an equal number of branches, (2sX2p, 3sX3p, 4sX4p, etc...) then the overall inductance of the circuit will be identical to one woofer, and thus the inductance becomes a non-issue, and there will be no difference in impulse response... There simply CANNOT be.
If your mistake is wiring too many woofers in series, then try a different wiring scheme, OR start with higher impedance woofers, and wire down to your desired impedance using PARALLEL wiring, not series wiring.
Back-EMF, you say? Nope, I still don't buy that. The output devices in the amplifier have a FAR lower impedance than all of the woofers combined. The back-EMF will want to be shorted through the amp. Tube amplifiers, POSSIBLY, but still not a noticeable acoustic smearing directly attributable to back-EMF.
Long story short, Try a different wiring scheme, and use more parallel resistances than series resistances, and start with drivers that offer the lowest inductance (rated in mH) and highest impedance (rated in Ohms) you can find.
DYohn 
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Location: Arizona, United States
Posted: May 05, 2011 at 10:38 AM / IP Logged  
Damn Dave, I feel like I need to send you roses or something after that.  woofer wiring confusion - Page 2 - Last Post -- posted image.
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