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PostPosted: 26 Feb 2019, 10:00 
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Joined: 19 Oct 2018, 15:30
Posts: 132
Location: Montréal, Québec
Hello everyone. my friend and I are about to rebuild the crossover of our speakers. mine are cerwin-vega AT-15 and my friend’s speakers are pioneer HPM-900. I have an electrical circuit for the pioneer, but despite much research, I have not found a circuit for the AT-15. I need some information to make this rebuild a success.

First, I would like to know which is the best type of wire to use to redo the internal connections of the speakers. Solid core? stranded? copper? silver plated copper? twisted pairs or not? wich gauge? I see too many possibilities and I do not know what to choose.

Then, how to choose the right inductors? I plan to buy Solen's components since they are located near my home. On their site, I was able to find inductors with the exact specifications of the HPM-900 electrical circuit. inductance and resistance are exactly the same as on the electric circuit, but the shape and dimensions are different. do these settings have an impact on audio rendering?

Also, how to choose the right inductors if I do not have access to the inductor's resistance spec? I understand that the gauge of the inductor wire has a direct impact on its resistance. Is there a reliable way to choose the right one without having to disassemble those already present to measure their resistance?

Finally, the adjustments for mid and trebble do not work on cerwin vega. Both speakers behave exactly the same way. There is a potentiometer and the other section is controlled by what I think is an L-pad. Both adjustments have no impact on the sound on both speakers. I know I could try to clean them, but I doubt that this is the same problem for the 4 adjustments at the same time. Is it possible that the problem is caused by other parts that are defective, or the adjustments themselves are the only ones that can cause this problem? Again, is there a way to find the problem without dismantling the actual crossovers ? I thought maybe use my signal generator to check for cross-over points. If I understand correctly, the crossovers points should change as I turn the adjustments?

Thank you all for your help and I will post pictures tonight so that everyone can refer to them.
BTW if you know where to find Electrical diagram for the AT15, please let me know.


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PostPosted: 26 Feb 2019, 18:00 
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Joined: 23 Feb 2017, 02:02
Posts: 559
Inductor dc resistance dosen't matter as normally small and dosen't make much diffrence.
Shape dosen't make much diffrence but quailty does, buying more expensive and fancy hifi series inductors and capacitors will make diffrence to sound.

Larger gauge wires minimizes the voltage drop accross the wires and yeilds better sound quality.
As speaker is inductive the indutive out of phase current will cause small ammounts of voltage drop accross wire. V=IR
This small ammounts of voltage will turn into audititable distortion.

THe L pad sets the volume, it seems like the pads are broken or bypassed to direct input


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PostPosted: 27 Feb 2019, 01:08 
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Joined: 23 Feb 2017, 02:02
Posts: 559
A L pad has connected properly with speaker yeilds a voltage divider circuit but having a constant 8ohms on the input to the cross over circuit.
This sets the speaker volume.

At one setting is directly to speaker 8R, at another volume setting is 4r from L pad and 4r speaker total, another setting is 6r from L pad and 2R speaker, etc.
Total input resistance always 8r
This reduces voltage at speaker.


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PostPosted: 03 Mar 2019, 12:45 
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Joined: 19 Oct 2018, 15:30
Posts: 132
Location: Montréal, Québec
Thanks for your very informative answer ! I decided to try to clean the pots and L pads before buying any parts. I don’t think i’ll be able to find the exact same L-pads


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PostPosted: 03 Mar 2019, 23:42 
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Joined: 23 Feb 2017, 02:02
Posts: 559
As long as you can fit the L pads and have high enough power ratings should be good replacement.


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