TalkBass Forums WHAT'S THE IMPEDANCE OF MY BASS CAB?

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#1
11-21-2012, 01:11 PM
 Registered User Join Date: Aug 2011
WHAT'S THE IMPEDANCE OF MY BASS CAB?

Hello
I've bought a 2006 user SWR GOLIATH III (4x10), but I don't know the impedance. I want to use it with my EDEN WT-600 in bridge mode to have full power and the bridge mode minimum it's 8 Ohm. I don't know if I can use this cab or not..

Some people say we must multiply the multimeter result by 1,3 factor to know the impedance correct.
I did some measurements but I still don't know:

GOLIATH 4X10 = 4,3 ohm (if multiply by 1,3 = 5,59)

EACH DRIVER FROM GOLIATH 4X10 = 4,4 (x 1,3 = 5,72)

AN AGUILAR 12'' 8 OHM CAB = 6,4 (x 1,3 = 8,32)

A GAUSS DRIVER 8 OHM = 5 (x 1,3 = 6,5)

A 8 OHM DRIVER = 7,2 (x 1,3 = 9,36)

A 4 OHM DRIVER = 3,2 (x 1,3 = 4,16)

So, the question is: MY GOLIATH 4X10 IT's 4 Ohm or 8 Ohm?

Someone can help? Thank you in advance
#2
11-21-2012, 01:28 PM
 Registered User Join Date: Sep 2004 Location: Chicago
I'm going to venture that it's 4ohm -- if it advertised itself as an 8ohm cab and was actually 4-5 ohms, people's amps would be getting destroyed.

And I'd say for sure -- if the amp says it's only rated for an 8ohm cab in bridged mode, do not play it through a cab that your meter is showing as 4.3ohms (even at 5.5ohms).

Got a serial number? Maybe there's a clue on the back panel. Worst case -- you could take it apart and check the individual drivers and the wiring...

Good luck!
ltt
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#3
11-21-2012, 01:44 PM
 Registered User Join Date: May 2011
It's rated at 8 ohms here:

http://www.americanmusical.com/Item-...OLIATHIII-LIST

So it's probably worth verifying, as it just might be 8 ohm.
#4
11-21-2012, 01:56 PM
 Registered User Join Date: Sep 2004 Location: Chicago
Pretty sure they make the Goliaths in 4 and 8 ohm configs:

http://www.musiciansfriend.com/ampli...-cabinet-4-ohm
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#5
11-21-2012, 02:03 PM
 Registered User Join Date: Aug 2011
EACH DRIVER FROM GOLIATH 4X10 = 4,4 (x 1,3 = 5,72)

and yes, it has a serial number. I'll check it.

thank you
#6
11-21-2012, 02:17 PM
 Registered User Join Date: Aug 2012 Location: Germany
Emiminence Deltalite II 2510/2512

Re: 5 Ohm

* 1.3

= 6.5 Ohm

?????

So do that mean the Emminence enigineers are stupid people?

Last edited by ThisBass : 11-21-2012 at 02:29 PM.
#7
11-21-2012, 02:24 PM
 Registered User Join Date: Mar 2011 Location: Central NJ
Did you measure the individual drivers while they were completely disconnected from the wiring? It doesn't make sense because your measurements of other drivers and cabs appears proper. 4.4 ohm DCR I have never seen.
#8
11-21-2012, 02:32 PM
 Registered User Join Date: Aug 2012 Location: Germany
He told:
Quote:
 Originally Posted by fernandobicho2 EACH DRIVER FROM GOLIATH 4X10 = 4,4 (x 1,3 = 5,72)
#9
11-21-2012, 02:35 PM
 Registered User Join Date: Aug 2012 Location: Germany
Quote:
 Originally Posted by lethargytartare And I'd say for sure -- if the amp says it's only rated for an 8ohm cab in bridged mode, do not play it through a cab that your meter is showing as 4.3ohms (even at 5.5ohms).
or even the "calculated" 6.5 Ohm for the Emminence Deltalite ...
#10
11-21-2012, 02:54 PM
 Registered User Join Date: Sep 2004 Location: Chicago
So, if each driver is measuring 4.4, then they're 4ohm drivers.

With 4 x 4ohm drivers, you can't get an 8ohm total impedance:

4 in parallel = 1ohm
pairs in series = 8ohms each, in parallel = 4ohms total
all in series = 16ohms

But the core issue for you is simple: your amp is only rated to play in bridged mode through an 8ohm cab -- you definitely don't have that, so don't do it
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#11
11-21-2012, 03:04 PM
 Registered User Join Date: May 2011
The 8 ohm version has "8 OHM" right on the grill:

http://www.americanmusical.com/Item-...OLIATHIII-LIST

http://www.musiciansfriend.com/ampli...-cabinet-4-ohm
#12
11-21-2012, 03:14 PM
 Registered User Join Date: Aug 2012 Location: Germany
Quote:
 Originally Posted by lethargytartare So, if each driver is measuring 4.4, then they're 4ohm drivers.
What's about the 5 Ohm like the Emminence Deltalite?
These are then 4 Ohm or probably 6 Ohm Drivers?

Quote:
 Originally Posted by lethargytartare With 4 x 4ohm drivers, you can't get an 8ohm total impedance:
so that means the Emminence Deltalite are garbage,
because of you can do nothing with 6 Ohm ...

Quote:
 Originally Posted by lethargytartare But the core issue for you is simple: your amp is only rated to play in bridged mode through an 8ohm cab -- you definitely don't have that, so don't do it
So hope for yourself you'll never play Emminence Drivers ...
#13
11-21-2012, 03:28 PM
 Registered User Join Date: Oct 2009 Location: Baltimore, MD
DC resistanse does not equal impedance. The correction factor listed *1.3 is simply a "guide". From what I've read, 4 ohm drivers generally read down below 4 ohms in DC resistance. Most of these speakers listed are likely nominal 8 ohm drivers.
#14
11-21-2012, 04:19 PM
 Registered User Join Date: Aug 2009 Location: New Zealand
The extra bridge power isn't necessary to get good volume out of that cab. A 300W amp is plenty powerful enough to stress it even if it was 8 ohms.
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#15
11-21-2012, 05:02 PM
 Registered User Join Date: May 2008
Quote:
 Originally Posted by lethargytartare So, if each driver is measuring 4.4, then they're 4ohm drivers. With 4 x 4ohm drivers, you can't get an 8ohm total impedance: 4 in parallel = 1ohm pairs in series = 8ohms each, in parallel = 4ohms total all in series = 16ohms But the core issue for you is simple: your amp is only rated to play in bridged mode through an 8ohm cab -- you definitely don't have that, so don't do it
I tend to agree with lethargytartare, but I'll add a few things to try -

Most dvms except maybe the cheapest most worthless models will have a way to "zero" the reading you get so that the resistance reading at that low of a value is eliminating the test leads from mucking up the reading. Usually you touch the leads together and push a button somewhere on the unit (zero, or calibrate) until the reading is zero.

http://www.colomar.com/Shavano/4x12wiring.html

You might be able to discern the wiring of your cab - (parallel, or series parallel) by tracing the wires to see if it matches any of the diagrams. Some cabs are wired pretty neatly, some can be a rats nest. Hope this helps.
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#16
11-21-2012, 05:41 PM
 Registered User Join Date: Mar 2007 Location: Mount Airy, North Carolina
Sorry, I had to go back to school on this subject.

Last edited by NYCbassist : 11-22-2012 at 04:27 PM.
#17
11-21-2012, 09:02 PM
 Registered User Join Date: Sep 2004 Location: Chicago
Quote:
 Originally Posted by NYCbassist Plug a cable into the cabinet and then check resistance by touching the leads of your Multimeter to the + & - on the cable respectively. ... Why make it any more complicated than that..
Agreed -- I assumed he did something similar to get the "overall" value he listed as

"GOLIATH 4X10 = 4,3 ohm"
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#18
11-21-2012, 09:06 PM
 Registered User Join Date: Nov 2002 Location: the mojave desert, CA, USA
you can measure the impedance value yourself with a multimeter: plug a speaker cable into your cab, and measure impedance with positive and negative probes of your multimeter... oh wait...look! someone else already recommended this path...sorry for the repeat... good luck!
#19
11-21-2012, 09:23 PM
 Registered User Join Date: Sep 2004 Location: Chicago
Quote:
 Originally Posted by Bmorefoozler DC resistanse does not equal impedance. The correction factor listed *1.3 is simply a "guide". From what I've read, 4 ohm drivers generally read down below 4 ohms in DC resistance. Most of these speakers listed are likely nominal 8 ohm drivers.
You're right -- and so are the mad rantings of ThisBass -- I got my 8ohm Deltalite IIs out and they have a DCR of 5ohms.

So back to the OP...personally, I'd still feel better if I had a clear confirmation that the cab was rated 8ohms -- probably IS, but before I risked my amp, I'd be over-cautious.

And as someone else noted -- you probably don't NEED to run bridged to be enough volume out of that setup, but I wouldn't presume to tell you what you need for your application.

Continued good luck!
ltt
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#20
11-22-2012, 12:15 AM
 Registered User Proprietor Springvale Studios Join Date: May 2008 Location: Ipswich UK
Well,

Quote:
 Originally Posted by lethargytartare So, if each driver is measuring 4.4, then they're 4ohm drivers. With 4 x 4ohm drivers, you can't get an 8ohm total impedance: 4 in parallel = 1ohm pairs in series = 8ohms each, in parallel = 4ohms total all in series = 16ohms But the core issue for you is simple: your amp is only rated to play in bridged mode through an 8ohm cab -- you definitely don't have that, so don't do it
Look if it reads > 4 OHMS DCR on a cheap meter Its an 8 ohm nominal Impedance cab.
Here is an expensive DCR meter measuring an expensive eight ohm driver.

Most hobbyist DCR meters are highly inaccurate especially at the low end of the range.

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