Question about rewiring a 3-way bookshelf speaker to be 8 Ohm´s

[Fromthenorth]

Hi all, i´m rewiring two old pioneer speakers that have been tampered with, and i want to ask you folks for help. The reason why i´m rewiring those speakers is because im having out of phase issues with them and since from the time they were tampered with they have never quite sounded right to my ears. So i ask you :
Will this here give me an 8 Ohm load in a 3-way speaker system, for an amplifier that handles 8 Ohm -16 Ohm load?

 

[jplesset]

When you say, "tampered with", do you know what was done? The "crossover" you're showing isn't what I would expect to see in any decent commercial speaker. What you show isn't likely to give you what you're looking for, either. It might be better to show what the wiring is now.

 

[Dave Bullet]

Hi all, i´m rewiring two old pioneer speakers that have been tampered with, and i want to ask you folks for help. The reason why i´m rewiring those speakers is because im having out of phase issues with them and since from the time they were tampered with they have never quite sounded right to my ears. So i ask you :
Will this here give me an 8 Ohm load in a 3-way speaker system, for an amplifier that handles 8 Ohm -16 Ohm load?

Yes it will - you have put 2 8 ohm drivers in series = 16 ohms, then paired that with another 16 ohm driver so based on 1/r1 + 1/r2 + ... = 1/rt

1/16 + 1/16 = 2/16, therefore invert and divide = 8 ohms.

 

[Dave Bullet]

As for sound quality - you have put a 1.5uF cap inline with your midrange and woofer which will castrate all bass frequencies (remember the lower the value of cap - the more resistive at lower frequencies = more it will cut).

you've essentially created an "all treble" system. Might be good for calling cats in the neighbourhood

 

[Fromthenorth]

This is what the existing wiring looks like... as for tampered with how, im not quiet sure how exactly it was´,as it was about ten years ago when the stereo system went into repair, all i remember is that the repair guy talked about he´d done something with the speakers to make them somehow sound bigger.

 

[Fromthenorth]

As for sound quality - you have put a 1.5uF cap inline with your midrange and woofer which will castrate all bass frequencies (remember the lower the value of cap - the more resistive at lower frequencies = more it will cut).

you've essentially created an "all treble" system. Might be good for calling cats in the neighbourhood

Cats are cool, up to a point.
Ok so what kind a cap should i then put instead there and where exactly (all i am thinking is not giving the mid-range to much low freq. to run through it)

 

[PeteMcK]

re:"Yes it will - you have put 2 8 ohm drivers in series = 16 ohms, then paired that with another 16 ohm driver so based on 1/r1 + 1/r2 + ... = 1/rt" - this is true only if you ignore the crossover components, which you can't....
Using the original wiring scheme, try inverting the phase of the woofer

Edit - one other thing to try - try connecting the end of the tweeter cap not connected to the tweeter to the terminal of the midrange unit that's connected to the mid cap (should give better protection to the tweeter & steeper roll off), Once again try changing the phase of the drivers

 

[Fromthenorth]

This is what the speaker spec sheet that came with the speakers originally says,and it also has a graph for frequency response and the impedance:
Bass reflex type, 3-way 3speaker system
Woofer.. 20cm..(8 in) cone type
Midrange..7.7cm..(3 in) cone type
Tweeter.. 6.6 cm..(3 in) cone type
Frequency range 45 to 20,000 Hz
Input impedance 8 Ohm
Sensitivity 87.5 db/W at 1 m distance
Music Power (DIN)140 W
Crossover frequency 4,000/10,000 Hz
Dimmension,, 261(W)x540(H)x227(D) mm

 

[wolf_teeth]

This is what the speaker spec sheet that came with the speakers originally says,and it also has a graph for frequency response and the impedance:
Bass reflex type, 3-way 3speaker system
Woofer.. 20cm..(8 in) cone type
Midrange..7.7cm..(3 in) cone type
Tweeter.. 6.6 cm..(3 in) cone type
Frequency range 45 to 20,000 Hz
Input impedance 8 Ohm
Sensitivity 87.5 db/W at 1 m distance
Music Power (DIN)140 W
Crossover frequency 4,000/10,000 Hz
Dimmension,, 261(W)x540(H)x227(D) mm

What the xovers state is about what you would have with the original wiring before what you proposed to change it.

What you're not seeing is that the impedance character of each driver is rising in terms of rolloff because of the capacitors and the inductance of the woofer. The inherent rolloff of the drivers also has a factor in the frequency response. The drivers are not directly in parallel to each other as you propose because of the filtering components. It is already likely a nominally 8 ohm system without any changes.

The issues you hear in sound could very well likely bedue to polarities of the drivers as suggested. Give that a try, and leave the wiring positions intact for now.

Later,
Wolf

 

[KatieandDad]

This is what the existing wiring looks like... as for tampered with how, im not quiet sure how exactly it was´,as it was about ten years ago when the stereo system went into repair, all i remember is that the repair guy talked about he´d done something with the speakers to make them somehow sound bigger.

Although it appears that you have paralleled speakers they are in fact independent because of the crossover points. The original design is 8 Ohms nominal impedance.

Of course it is far more complex than that but that is what nominal impedance is all about.

 

[mjf]

what model number do your speakers have?


http://www.diyaudio.com/forums/multi-way/211735-pioneer-cs-e500-capacitors-value.html

 

[Fromthenorth]

what model number do your speakers have?


http://www.diyaudio.com/forums/multi-way/211735-pioneer-cs-e500-capacitors-value.html

The model is S-J300