WHAT'S THE IMPEDANCE OF MY BASS CAB?

[lethargytartare]

Originally Posted by Bassmec

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.

See my post #19

[Bassmec]

Originally Posted by fernandobicho2

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

The idea that times 1.3 of the DCR gets you a nominal impedance figure
Is utter bollocks, you have an inaccurate meter an i'll informed friend and an 8 ohm nominal impedance Goliath 4x10.

[Munjibunga]

Originally Posted by Bassmec

The idea that times 1.3 of the DCR gets you a nominal impedance figure
Is utter bollocks, you have an inaccurate meter an i'll informed friend and an 8 ohm nominal impedance Goliath 4x10.

You're probably right. A 4-ohm cab will have a DC resistance of less than 4 ohms. My first thought was the volt-ohm meter needs to be calibated. Did the OP short the test leads to set the VOM to zero? Did he set the range to the lowest setting? Is it a quality instrument?

[oerk]

Originally Posted by Bassmec

The idea that times 1.3 of the DCR gets you a nominal impedance figure
Is utter bollocks, you have an inaccurate meter an i'll informed friend and an 8 ohm nominal impedance Goliath 4x10.

+1

Straight and to the point.

Additionally, try the cab with your amp in non-bridged mode first. If you're able to stress it (speakers begin distorting, be careful and use your ears!), don't bother with bridge mode. The amp generally runs hotter and with a worse damping factor when bridged.

[fernandobicho2]

Thank you all.

The speakers in the Goliath III are linked two in series and two in parallell.

SWR make Goliaths III in both 4 ohm and 8 ohm

The first series of the Goliath III don't show in the grill the legend "4 ohms" or "8 ohms". That's the problem

In basschat.co.uk I saw a thread where a user says his 8 ohm Goliath III, with the multimeter measure 6,02 ohm

The Goliath 4x10:


Each driver of the Goliath 4x10


A Gauss 8 Ohm


An ordinary driver 8 ohm


An ordinary 4 ohm driver


an Aguilar 12'' 8 ohm cab


Well. I'm still confused, but most opinions says the Goliath III it's a 4 ohm cab.

Thank you

[Downunderwonder]

Your meter low range is 100 ohm, if it was 10 ohm you could be more confident in your readings. Either way you won't be bridging which is a good idea if you think about the carnage you would unleash. 1200W peaks and 400W cabs don't get along well.

[oerk]

If the measured DC resistance is greater than 4 ohm, it's almost certainly an 8 ohm speaker.

Especially since the model number has an 8 as the last digit. This thread seems to back that assumption:
http://www.badassbassplayers.com/for...hp?f=38&t=7367

Most likely, the 4 ohm version had four of the BG1080C 16, all in parallel, whereas the 8 ohm version had four of the BG1080C 8, in series and parallel.

[Downunderwonder]

Make sure it is series parallel when you're done.

[Arjank]

The Re impedance is the DC resistance you can measure with a multimeter. The "real" frequency depended impedance is measured in a totally different way.
The lowest measured frequency depended impedance(impedance dip) is what you should look for to see if the amp can handle the cab.
There are lots of 4ohm cabs(or loudspeakers in general) that have a minimum impedance somewhere(at some frequency) of 3ohms. When that 3ohm dip is above say 200hz and is only in a narrow band I wouldn't be scared to use the cab with a 4ohm stable amp.

When those Goliath 10's measure 4.4ohms Re then they would be 6ohm drivers (according to DIN).
If you would run two of these cabs parallel I would recommend to use a 2(3)ohm stable amp.

[ThisBass]

It looks like anybody out there as well misinterpreted the DC reading.

10" SWR guitar speaker woofer 4 ohms BG1080C-8
"...model # BG1080C-8, measures 4 ohms. "

http://www.ebay.com/itm/10-SWR-guita...p2047675.l2557

[ThisBass]

Originally Posted by Arjank

When those Goliath 10's measure 4.4ohms Re then they would be 6ohm drivers (according to DIN).
If you would run two of these cabs parallel I would recommend to use a 2(3)ohm stable amp.

That means the very popular Emminence Deltatlite are 6.5 Ohm drivers (according to DIN).

That means any 4 Ohm cabs with Deltalite inside are 3.25 Ohm cabs ...

That means a lot of 4 Ohm amps probably died in the past because of too much output current.

Whereas DC of 7.2 Ohm calculates to a 9..10 Ohm driver.
That means a 2.7 Ohm cab is probably a 3.2 Ohm cab. That is the same impedance like the "real" impedance of the SWR 4 Ohm cab


BTW it is a general behavior of any driver that real impedance is most of the time different to the nominal.
The impedance of any driver depends on the frequency spectrum of the signal.

If the frequency spectrum is unknown means that the impedance of the driver is unknown ...
For any nominal 8 Ohm driver it is possible to get values significant different to the nominal.
Depending on the frequency spectrum this real impedance can be anything between 6..10 Ohm
But Extreme situations can be close to Zmin or twice the nominal.

Give huge amount of bass boost with the eq to your signal will probably double the impedance of nearly every cab (for lower notes played on the instrument).

The DC reading indicates the "nominal" rating (or general "nominal" behavior of a driver) but, never the real impedance that depends on the "real" frequency spectrum.

[fernandobicho2]

I think this drivers are PAS. SWR change to EMINENCE in 2007 with the Goliath IV. Right or wrong?

[lethargytartare]

Originally Posted by oerk

If the measured DC resistance is greater than 4 ohm, it's almost certainly an 8 ohm speaker.
...

I'm here after a bit more reading -- I didn't realize the DCR would be so much lower...and I'm surprised I didn't pay closer attention to that when I was first buying head-cab rigs. But as long as the amp and cab manufacturers all use the nominal ratings, you're ok and don't really NEED to know the difference.

As I mentioned, my Deltalite IIs are marked 8ohm and measure 5ohm with a multimeter. And with the series-parallel setup, 4x8ohm would give you an 8ohm cab. To be absolutely sure, though, you can still send the serial number to SWR and ask them to confirm...you'll get a clearer answer than this thread managed (and I freely accept part of THAT blame hahaha)

Originally Posted by ThisBass

The DC reading indicates the "nominal" rating (or general "nominal" behavior of a driver) but, never the real impedance that depends on the "real" frequency spectrum.

So the Eminence site, and most other places, don't use DCR and nominal interchangeably -- quite the opposite. But I think the conclusion is right. Here's a quote from the Eminence site:

"This is the DC resistance of the driver measured with an ohm meter and it is often referred to as the ‘DCR’. This measurement will almost always be less than the driver’s nominal impedance."
http://www.eminence.com/support/unde...dspeaker-data/

[fernandobicho2]

yeah, THANK YOU. But I believe this Goliath III has P.A.S. drivers. Not Eminence.

Could a driver measuring 4.4 ohm (5,72 ohm if we multiply by 1,3 factor) be a 8 ohm driver?

I've sended the question to SWR. They answered me in spanish telling:
Exist two kinds of Goliath III, one with reference 441 0500 400 working at 4 Ohms and other with ref. 441 0500 800 with 8 Ohms.
Now I've sended the serial. Let's see what they say.

Thank you all for the help.

[lethargytartare]

To the best of my knowledge at this point, yes, a 4.4 COULD be an 8ohm nominal.

If you search TalkBass, this same speaker came up in another thread and there the brief conclusion was that it was an 8ohm driver.

The label on the speaker -- BG1080C 8 -- that trailing 8, and possibly the '8' in '1080' could also mean 8ohms. Here's a directory of several spec sheets for PAS drivers:

http://www.pas-toc.com/pdf/drivers/

There you can find several speakers, most of which have the first 2 digits indicating the cone size, and they're all 8ohm and they all have 8 as the third digit...meaningful? I can't say for sure. MOST of those have a DCR/Re in the mid 5s range, but there is one that has a nominal 8ohm and a DCR/Re of 4.6. So, again, possible? Yes.

Here's a thread discussing Fender speakers, and an 8ohm driver that was measuring 3.8 Re.

Fender PRO 810, 8ohm drivers read 3.8ohms

Here's a back and forth about a 16ohm speaker that was measuring 7ohms Re. Everyone thought it was too low, but the guy tested the voltage drops and they concluded that it was, in fact, a 16ohm speaker:

http://www.marshallforum.com/cabinet...-3x16ohms.html

So note -- that thread gives you a way to test the voltage drop yourself and figure it out. That could be really educational.

[Arjank]

Originally Posted by lethargytartare

To the best of my knowledge at this point, yes, a 4.4 COULD be an 8ohm nominal.

If it is a dip in a very narrow frequencyband and the rest is 8ohms or higher would say yes, else no.

[fernandobicho2]

Thank you.

Another fact:

This Goliath III has two drivers linked in series and other two in paralell....

They're all equals... so, like that,

If they're 4 ohm, thant gives what impedance for the cab?

If they're 8 ohm, that gives what impedance for the cab?

And the next Goliath III series have the Ohm information in the grill :

Some say 4 Ohm. Someone have one? Can check the impedance with a multimeter?

Some say 8 Ohm. Someone hane one? Can check the impedance with a multimeter?

It was too much to ask to check the links inside. As far as I know, they could be all speakers in series if it's a 4 ohms cab (I read in that case they're 16 ohm speakers), and one pair in series and the other pair in paralell if it's a 8 ohm cab.

[Arjank]

Originally Posted by ThisBass

That means the very popular Emminence Deltatlite are 6.5 Ohm drivers (according to DIN).

That means any 4 Ohm cabs with Deltalite inside are 3.25 Ohm cabs ...

That means a lot of 4 Ohm amps probably died in the past because of too much output current.

Whereas DC of 7.2 Ohm calculates to a 9..10 Ohm driver.
That means a 2.7 Ohm cab is probably a 3.2 Ohm cab. That is the same impedance like the "real" impedance of the SWR 4 Ohm cab

What I meant to say is that a driver with an Re of 4.4 ohms would fall in the 6ohm category. And 3.1ohm e.g. would fall in the 4ohm category. And 5.9 e.g. would fall in the 80hm category.

And yes, an amp could die when the impedance drops below 3ohms in a broad frequency range and the amp is only 4ohm stable......

[Arjank]

Originally Posted by fernandobicho2

Thank you.

Another fact:

This Goliath III has two drivers linked in series and other two in paralell....

They're all equals... so, like that,

If they're 4 ohm, thant gives what impedance for the cab?

If they're 8 ohm, that gives what impedance for the cab?

4 and 8ohms

[Arjank]

Originally Posted by lethargytartare

The label on the speaker -- BG1080C 8 -- that trailing 8, and possibly the '8' in '1080' could also mean 8ohms. Here's a directory of several spec sheets for PAS drivers:

http://www.pas-toc.com/pdf/drivers/

E.g. check the LX-2800 PAS driver, the Re is 4.6 ohms and if you look at the impedance CURVE, you'll see that between 80 and 200hz it's approx 6ohms. Thats why I say that according to DIN such a driver would fall in the 6ohm category and not 8.
Connect two of those parallel and the region between 80 and 200hz will be 3ohms. You need a stable poweramp to drive these at high SPL levels.