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8ohms + 6 ohms?


mikebass84
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Sorry I know there's a whole thread on impedance but I just can't seem to find what I need. My rig is an Ashdown EB180 (4ohm min) run into an Ashdown 210t (which is now 6 ohms as i've had a speaker replaced) and a custom built 15" (8ohm).

Now I would ideally like to run the Ashdown into both cabs in parallel to get the most out of it but I have no idea if it's safe to do so with the load I am dealing with.

Simple question. If I run both cabs parallel will I damage my head?

Cheers

Mike

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[quote name='dincz' timestamp='1398281502' post='2432512']
A 6 ohm 2x10? How does that work?
[/quote]
[quote name='mikebass84' timestamp='1398281741' post='2432519']
No idea. The guy who fixed the cab ssaid it's now 6ohm B-)
[/quote]

Hmm.... an 8 and 16 in parallel?
Sounds a good fix.....

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Without putting my thinking head on and calculating this, it will be just under the 4 ohms total, from the simple fact that two 8ohms in parallel wil give you 4 ohms. But the main concern to me would be that the 2x10 at 6 ohms will take the most power and depending on the efficiency of the 10's compared to the 15" the sound could be quite unballanced from each cab. I feel this may be more of a problem than the total impedance the amps sees, as the extra cone area may result in you not being tempted to drive the rig too hard?? un balanced sound levels due to unknown speaker efficiency is the risk here.

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Isn't Bugera Behringer? Open things up & have a look at the drivers, see what's on them. You could then buy a couple of 16Ω drivers to suit the cab volume & put them in.
Or maybe a better idea, flog it & get a matching 15 to the one you have (that's if you like the sound of it, of course).

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[quote name='Dad3353' timestamp='1398290227' post='2432656']
Fixed :mellow:
[/quote]
Nope. 8 and 4 ohm speakers in parallel gives 2.6 ohms. 8 and 16 ohm speakers would be 5.3 ohms, which is as close to 6 ohms as it'll get.

I think I'd want to know exactly what this guy has done to the Ashdown before I went any further.

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[quote name='Musky' timestamp='1398292270' post='2432691']Nope. 8 and 4 ohm speakers in parallel gives 2.6 ohms...[/quote]

[URL=http://www.smileyvault.com/][IMG]http://www.smileyvault.com/albums/CBSA/smileyvault-cute-big-smiley-animated-041.gif[/IMG][/URL]

:blush:

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If these are the specs for the [url="http://www.dawsons.co.uk/ashdown-mag-210t-deep-cabinet-250w?gclid=COeF0NT7-L0CFUoCwwodXpsAZg"]Ashdown 2x10T[/url] it being 4Ω cab, I assume it has two 8Ω speakers in parallel.
So if one of the speakers is 8Ω the only off the shelf way of getting 6Ω is adding a 16Ω speaker to the existing wiring.
Ok it is really 5.3333333Ω but that is 6Ω to the average joe who does this type of install.


Edit: ignore this as they also do an 8Ω 210T cab.

Edited by goingdownslow
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[quote name='goingdownslow' timestamp='1398330730' post='2432883']
If these are the specs for the [url="http://ashdownmusic.com/products/1/Bass-Amplification/3/MAG/37/MAG-210T-Deep-Cab/"]Ashdown 2x10T[/url] it being 4Ω cab, I assume it has two 8Ω speakers in parallel.
So if one of the speakers is 8Ω the only off the shelf way of getting 6Ω is adding a 16Ω speaker to the existing wiring.
Ok it is really 5.3333333Ω but that is 6Ω to the average joe who does this type of install.
[/quote]
But it was originally an 8ohm cab not a 4ohm cab

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If the 210 cab was originally 8 ohms then that means two 16 ohm speakers in parallel or two 4 ohms in series.

A replacement parallel speaker would have to be 8 ohms to give '6' ohms (8+16 = 5.3 ohms).

A replacement series speaker would have to be 2 ohms to give 6 ohms.

When connecting two speakers/cabs in [u]parallel[/u], the resulting ohms will [u]always be less[/u] than the lowest value cab/speaker.

It's not clear why the OP had one speaker replaced, but if it was supposed to be a repair then I'd be sending it back and asking that it be done properly.


Here's a useful calculator for parallel resistances: http://www.1728.org/resistrs.htm

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[quote name='mikebass84' timestamp='1398335131' post='2432981']
I've just taken a look at both speakers. The original speaker is 16ohm and the replacement is 4ohm.

I would ssend it back to get the proper speaker fitted but the guy's no longer in the country :-\
[/quote]

That makes the cab either 3.2 or 20 ohms and messes up the power distribution between the two drivers. Still, leaving the country seems a bit of an over-reaction.

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Sorry, but that's a proper bodge job. It's not a repair but a modification - and not a good one. :(

There are only two ways to connect 16 and 4 ohms speakers and the result will be 20 ohms (series) or 3.2 ohms (parallel).

If it has been wired in series to give a 20 ohm cab, then adding a second 8 ohms cab (in parallel) would give a total load of 5.7 ohms, so perhaps that's what he meant by 6 ohms?

But if the speakers are connected in parallel (as they were in the original cab) and he has done the same with a 4 ohm speaker, then he's left you with a cab that is below the minimum requirement for your amp and therefore the possibility of damaging the amp.

Edited by flyfisher
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Yeah I'm gonna ask him how he's wired the speakers up. I'm really hoping he's done it in series so I can still use my full stack if needed or just the 15" for smaller gigs.

At least till I can afford to buy myself the right speaker and I'll just wire the thing myself

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