Official Barefaced Bass Cab Club

[Plutonium244]

Three people and three different impedance calculations. Math is a funny thing! Maybe I should just stick to playing the bass.

My calculation is the same as broncobenshea: 60% to the One10 and 40% to the Two10 meaning that the driver in the One10 is getting 3 times the power that either of the drivers in the Two10 are getting.

 

[mcnach]

Three people and three different impedance calculations. Math is a funny thing! Maybe I should just stick to playing the bass.

Math is not a funny thing, it's pretty precise, specific, and unambiguous when we talk arithmetic...

 

[Downunderwonder]

Three people and three different impedance calculations. Math is a funny thing! Maybe I should just stick to playing the bass

yeah. I am not sure of the calculation but intuitively a 12 ohm cab would get 1/3 of power when paired with a 8 ohm cab.

2 woofers in the 210 get 1/3 so 1/6th each and the single gets 4/6 all to itself, which is 4 times 1/6th.

 

[Mushroo]

Ah, I was making the assumption that the One10 and Two10 use identical drivers of impedance X.

So the One10 has 1 driver of impedance X, for a total impedance of 1X, while the Two10 has two drivers of impedance X wired in series for a combined impedance of 2X.

Therefore the One10 with impedance X gets twice as much juice as the Two10 with impedance 2X. You don't even need to know the value of X to make this calculation.

If I'm incorrect in my assumption that the cabinets both use the same 10" drivers, then my math is very wrong!

 

[Plutonium244]

yeah. I am not sure of the calculation but intuitively a 12 ohm cab would get 1/3 of power when paired with a 8 ohm cab.

2 woofers in the 210 get 1/3 so 1/6th each and the single gets 4/6 all to itself, which is 4 times 1/6th.

It is kinda funny that we're getting all manner of calculations here... but by my calculation (which is really just an online calculator), the 8-ohm One10 gets 60% of the power and the Two10 gets 40%, which is 20% per driver, so 60% is 3x 20%, rather than 4x. So if I am wrong, I blame anonymous internet pages. And possibly my own ignorance.

 

[Plutonium244]

Ah, I was making the assumption that the One10 and Two10 use identical drivers of impedance X.

So the One10 has 1 driver of impedance X, for a total impedance of 1X, while the Two10 has two drivers of impedance X wired in series for a combined impedance of 2X.

Therefore the One10 with impedance X gets twice as much juice as the Two10 with impedance 2X. You don't even need to know the value of X to make this calculation.

If I'm incorrect in my assumption that the cabinets both use the same 10" drivers, then my math is very wrong!

Well, I am probably near the bottom of the class in my working knowledge of electronics, but wouldn't two 8-ohm drivers have 1/2 the impedance of one 8-ohm driver, rather than double? Those two 8-ohm drivers is what gives the Two10s its 4-ohm option, I'd suppose. Not sure how things have to be wired to get the 12 ohm option.

 

[Mushroo]

Well, I am probably near the bottom of the class in my working knowledge of electronics, but wouldn't two 8-ohm drivers have 1/2 the impedance of one 8-ohm driver, rather than double? Those two 8-ohm drivers is what gives the Two10s its 4-ohm option, I'd suppose. Not sure how things have to be wired to get the 12 ohm option.

Hypothetically for the sake of argument: If you have two drivers with impedance 7 ohms, you can wire them in parallel for combined 3.5 ohm. Round that up to the nearest multiple of 4, and market the cab as 4 ohm nominal impedance. Or you can wire them in series for combined 14 ohm. Round that down to the nearest multiple of 4, and market it as a 12 ohm nominal cab.

Is there some third option that I've overlooked for how to wire a two-driver cab, other than series vs. parallel?

 

[Plutonium244]

Hypothetically for the sake of argument: If you have two drivers with impedance 7 ohms, you can wire them in parallel for combined 3.5 ohm. Round that up to the nearest multiple of 4, and market the cab as 4 ohm nominal. Or you can wire them in series for combined 14 ohm. Round that down to the nearest multiple of 4, and market it as a 12 ohm nominal cab.

Is there some third option for how to wire a two-driver cab that I've overlooked, other than series vs. parallel?

You may be right, I dunno. It would simplify things, conceptually for me anyway, if the switch in the Two10s is just between series and parallel, and you round to the number you want to get. Otherwise I am not sure how you get 12 ohms unless there's something in the line that regulates impedance.

There is a third way to wire speakers together, used by a too-large section of musicians. There's series, parallel, and fire-starting.

 

[Tim1]

You may be right, I dunno. It would simplify things, conceptually for me anyway, if the switch in the Two10s is just between series and parallel, and you round to the number you want to get. Otherwise I am not sure how you get 12 ohms unless there's something in the line that regulates impedance.

There is a third way to wire speakers together, used by a too-large section of musicians. There's series, parallel, and fire-starting.

I think you will find that it you put a meter across a single one 10 it reads 6Ohms, hence the 12 ohm switch. However as Alex has posted, it is not quite as simple as that because resistance can vary with frequency.....I think.....

 

[Plutonium244]

I think you will find that it you put a meter across a single one 10 it reads 6Ohms, hence the 12 ohm switch. However as Alex has posted, it is not quite as simple as that because resistance can vary with frequency.....I think.....

So their 4-ohm switching option is actually 3 ohms? I know the rules aren't hard and fast, but seems like the Two10s in 4-ohm mode, or two One10's, would be pushing the limits of 4-ohm-min capable amps, since they're actually a 3-ohm-load speaker configuration if you're correct... and reaching into territory meant to be handled by 2-ohm capable amps.

 

[anton72]

So their 4-ohm switching option is actually 3 ohms? I know the rules aren't hard and fast, but seems like the Two10s in 4-ohm mode, or two One10's, would be pushing the limits of 4-ohm-min capable amps, since they're actually a 3-ohm-load speaker configuration if you're correct... and reaching into territory meant to be handled by 2-ohm capable amps.

That's interesting. I always wonder how such tiny thing as One10 can be SO loud and efficient. I A/B it with my SM and One10 didn't sound quite "half" of it in terms of volume. They differ in frequency range of course but again, One10 seem to have similar output or is it just me...

 

[alexclaber]

So their 4-ohm switching option is actually 3 ohms? I know the rules aren't hard and fast, but seems like the Two10s in 4-ohm mode, or two One10's, would be pushing the limits of 4-ohm-min capable amps, since they're actually a 3-ohm-load speaker configuration if you're correct... and reaching into territory meant to be handled by 2-ohm capable amps.

I've answered this so so so so so so so many times. We've done the measurements and we've done the tests. The impedance numbers quoted are simply nominal impedance numbers to guide you regarding the load on your amp (so it's safe on solidstate or well matched on valve amps) and give you an idea of the power the amp will deliver. Please just use the nominal numbers we quote - the 10CR cabs are both very efficient and very easy loads.

If you search back you'll find me talking about impedance magnitude and phase vs frequency. That's what matters. If your supposition above was true then we'd have had loads of incidences of amps shutting down with the numerous One10 pairs or Two10 cabs out they're. Nothing ever has. They are an absolutely rock solid load.

 

[alexclaber]

That's interesting. I always wonder how such tiny thing as One10 can be SO loud and efficient. I A/B it with my SM and One10 didn't sound quite "half" of it in terms of volume. They differ in frequency range of course but again, One10 seem to have similar output or is it just me...

Why would a One10 be half the output of a Super Midget with the knobs in the same positions? There's only a 2dB difference in sensitivity and 1dB is generally considered the minimum increase you can hear. A Super Midget at full output has similar output to two One10 cabs at full tilt but twice the output in that sense doesn't sound twice as loud because hearing is logarithmic.

 

[broncobenshea]

Each cab is 4ohm. Usually daisychaining cabs puts them in parallel. That will give you a 2ohm load. In series, however it will be an 8ohm load. I've got a little connector box to allow me to do that. This is irrelevant of the number of outputs of the amp (the LM3 only has one, when there's two they're usually in parallel, and using them it's equivalent to plugging one cab to the amp, and the other cab to the first cab).

series: R = R1 + R2
parallel: 1/R = 1/R1 + 1/R2

what do you mean a little connector box?

 

[John D Harris]

I've answered this so so so so so so so many times. We've done the measurements and we've done the tests. The impedance numbers quoted are simply nominal impedance numbers to guide you regarding the load on your amp (so it's safe on solidstate or well matched on valve amps) and give you an idea of the power the amp will deliver. Please just use the nominal numbers we quote - the 10CR cabs are both very efficient and very easy loads.

If you search back you'll find me talking about impedance magnitude and phase vs frequency. That's what matters. If your supposition above was true then we'd have had loads of incidences of amps shutting down with the numerous One10 pairs or Two10 cabs out they're. Nothing ever has. They are an absolutely rock solid load.

No bone to pick WHATSOEVER, but...
Yes, you've covered this many times, but your rating #'s are what created all the confusion.
The Six10 is rated at 4 ohm.
When you rate the Two10 at 4 ohm those who can do math go ***?
I've read & understand all your explanations & agree that they make sense in the real world.
Just think it would be less confusing to use calculations based on the same rating per driver across all your 10" drivered cabs.

 

[broncobenshea]

I've answered this so so so so so so so many times. We've done the measurements and we've done the tests. The impedance numbers quoted are simply nominal impedance numbers to guide you regarding the load on your amp (so it's safe on solidstate or well matched on valve amps) and give you an idea of the power the amp will deliver. Please just use the nominal numbers we quote - the 10CR cabs are both very efficient and very easy loads.

If you search back you'll find me talking about impedance magnitude and phase vs frequency. That's what matters. If your supposition above was true then we'd have had loads of incidences of amps shutting down with the numerous One10 pairs or Two10 cabs out they're. Nothing ever has. They are an absolutely rock solid load.

So to clarify are you saying that running a Two10s and a One10 in a "4 Ohm" amp would most likely be safe? Even though the calculations bring it closer to 2.7ohm?

 

[alexclaber]

When you rate the Two10 at 4 ohm those who can do math go ***?

If you do the maths in the complex domain then it makes sense. And that's the real engineering. Nominal impedance numbers are just that - NOMINAL. Trying to do precise impedance maths with nominal numbers is just silly, like building an architectural model at 1:100 scale using duplo. Incidentally, if you put the T/S parameters for the 10CR250 into cab modelling software, some packages think it's an 8 ohm driver, some think it's 6 ohm. The important thing is that the really important thing is amp compatibility - and it's very very amp friendly, transistors or tubes.

For parallel connections, here's the numbers to use:

One10 = 8
One10 x2 = 4
One10 x3 = 2.7
One10 x4 = 2

Two10S@4 = 4
Two10S@4 x2 = 2
Two10S@4 + One10 = 2.7
Two10S@12 = 12
Two10S@12 x2 = 6
Two10S@12 x3 = 4

Four10@2 = 2
Four10@8 = 8
Four10@8 + Two10S@12 = 4
Four10@8 x2 = 4
Four10@8 + Two10S@12 x 2 = 4

Six10 = 4
Six10 + Two10S@12 = 4

Eight10 = 4

I think that's most of the combinations.

 

[alexclaber]

So to clarify are you saying that running a Two10s and a One10 in a "4 Ohm" amp would most likely be safe? Even though the calculations bring it closer to 2.7ohm?

No, I didn't say that. See the numbers I've posted now.

 

[Tim1]

I've answered this so so so so so so so many times. We've done the measurements and we've done the tests. The impedance numbers quoted are simply nominal impedance numbers to guide you regarding the load on your amp (so it's safe on solidstate or well matched on valve amps) and give you an idea of the power the amp will deliver. Please just use the nominal numbers we quote - the 10CR cabs are both very efficient and very easy loads.

If you search back you'll find me talking about impedance magnitude and phase vs frequency. That's what matters. If your supposition above was true then we'd have had loads of incidences of amps shutting down with the numerous One10 pairs or Two10 cabs out they're. Nothing ever has. They are an absolutely rock solid load.

Please everyone just read this and leave Alex alone now so he can get on with designing my new bass amp. If not a single amp has ever shut down then just trust his numbers and enjoy the gig.

 

[Mr. Foxen]

See all of this stuff is the problem that comes with people missing out the 'nominal' part of nominal impedance ratings. Its made up for convenience and doesn't really stand up when looked at too hard. Everyone is pretty reliant on the bodge so manufacturers have to go with it even when it doesn't really work.