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8x10 wiring fun


joegarcia
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[quote name='joegarcia' post='135450' date='Feb 7 2008, 02:03 AM']Hi,
Is it possilble to re-wire an 8ohm 8x10 cabinet to 4ohms by using series/parallel wiring? I don't know what the individual speakers are yet but does this sound plausible?

Ta's[/quote]

No.

If the cab is currently 8-ohms then:

If the speakers are all 4-ohm then they will get 8-ohms by having two strings of 4 speakers = 16-ohms in parallel, which brings it back down to 8-ohms.

The speakers can't be 8-ohms each because you can't make 8-ohms total.

If the speakers are 16-ohms then you would have two groups of 4 speakers in parallel = 4-ohms connected in series which adds up to 8-ohms.

The speakers can't be 32-ohms because you can't make 8-ohms total.

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[quote name='Hamster' post='135481' date='Feb 7 2008, 08:35 AM']He hasn't - but he wants one :) As above, should be able to do it with re-wiring.

Hamster[/quote]

Not if the cab is currently 8-ohms. There is no way to convert any 8-ohm cabinet into 4-ohms without changing the speakers.

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I feared this may be the case.
I don't know what individual impedance the speakers are yet as I haven't bought it as yet and the current owner doesn't know either. Probably won't if he's sure it's 8 ohms.
It's a 'touring' Ashdown ABM810. It looks like a normal 810 but has normal black drivers of some sort as opposed to the normal Blueline ones. 1200w as the standard ABM810s.

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[quote name='obbm' post='135480' date='Feb 7 2008, 08:34 AM']No.

If the cab is currently 8-ohms then:

If the speakers are all 4-ohm then they will get 8-ohms by having two strings of 4 speakers = 16-ohms in parallel, which brings it back down to 8-ohms.

The speakers can't be 8-ohms each because you can't make 8-ohms total.

If the speakers are 16-ohms then you would have two groups of 4 speakers in parallel = 4-ohms connected in series which adds up to 8-ohms.

The speakers can't be 32-ohms because you can't make 8-ohms total.[/quote]

Now you say that - I've sat down with a piece of paper and I think you're right. However - if you have a stereo amp that goes down to 2 ohms AND the speakers are all 8ohm then you might be in business. Parallel wire the 8ohm speakers into 2 stacks of 4 and that will give you 2ohms on each stack.

Hamster

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[quote name='Hamster' post='135603' date='Feb 7 2008, 11:35 AM']Now you say that - I've sat down with a piece of paper and I think you're right. However - if you have a stereo amp that goes down to 2 ohms AND the speakers are all 8ohm then you might be in business. Parallel wire the 8ohm speakers into 2 stacks of 4 and that will give you 2ohms on each stack.

Hamster[/quote]

Thanks but is it possible for the speakers to be 8ohm if they're wired up presently for 8ohms total?
Also, my amp does do 2ohms but I wanted to be able to use it with another 4ohm cab.

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[quote name='joegarcia' post='135622' date='Feb 7 2008, 11:56 AM']Thanks but is it possible for the speakers to be 8ohm if they're wired up presently for 8ohms total?
Also, my amp does do 2ohms but I wanted to be able to use it with another 4ohm cab.[/quote]


Only if he hasn't got all the speakers wired or he's found a way to circumvent the laws of physics, in which case I doubt that he'd be a musician.

This table shows all the possible permutations.

Speakers__ohms_____cab posibilities (ohms)

2__________4_________2 or 8
4__________4_________1 or 4 or 16
6__________4_________0.67 or 6 or 24
8__________4_________0.5 or 2 or 32

2__________8_________4 or 16
4__________8_________2 or 8 or 32
6__________8_________1.33 or 5.33 or 12 or 48
8__________8_________1 or 4 or 64

2_________16_________8 or 32
4_________16_________4 or 16 or 64
6_________16________2.67 or 10.67 or 24 or 96
8_________16_________2 or 8 or 128

2_________32________16 or 64
4_________32_________8 or 32 or 128
6_________32________5.33 or 21.33 or 48 or 192
8_________32_________4 or 16 or 64 or 256

I wish there was an easier way of doing a table :)

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[quote name='joegarcia' post='135594' date='Feb 7 2008, 11:19 AM']I feared this may be the case.
I don't know what individual impedance the speakers are yet as I haven't bought it as yet and the current owner doesn't know either. Probably won't if he's sure it's 8 ohms.
It's a 'touring' Ashdown ABM810. It looks like a normal 810 but has normal black drivers of some sort as opposed to the normal Blueline ones. 1200w as the standard ABM810s.[/quote]
If it has black speakers it sounds like quite an early Ashdown, or the Blueline ones have been replaced...? That may explain the 8ohms thing too!

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[quote name='Merton' post='135683' date='Feb 7 2008, 01:00 PM']If it has black speakers it sounds like quite an early Ashdown, or the Blueline ones have been replaced...? That may explain the 8ohms thing too![/quote]

Yea, think it may well be an older one. Anyone know how the older ones compare to the newer ones? Shame I can't re-wire it. Might still be ok though, my amp can handle 2.67 ohms and I wouldn't really mind it getting less power than the other cab although it's not ideal.

Edited by joegarcia
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[quote name='joegarcia' post='136212' date='Feb 8 2008, 12:46 AM']Yea, think it may well be an older one. Anyone know how the older ones compare to the newer ones? Shame I can't re-wire it. Might still be ok though, my amp can handle 2.67 ohms and I wouldn't really mind it getting less power than the other cab although it's not ideal.[/quote]
The black speakers were Celestions, blue ones are Sica. I prefer the Celestions personally, slightly punchier sound in my experience. Last time I played an 8x10 cab was an Ashdown with the blue speakers and it was horrible, destroyed the nice bright sound of the Hartke head used to power it.

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