Official Barefaced Bass Cab Club

[John D Harris]

This is a speaker impedance graph for a hi-fi speaker:

View attachment 2517386

The solid line is the impedance magnitude, the dashed line is the impedance phase. This speaker has relatively weak magnets compared to those found in modern bass cabs or PA speakers, so the impedance peaks are relatively low - in an 8 ohm bass or PA cab the peaks can reach around 100 ohm. The manufacturer of this speaker gives it an 8 ohm nominal impedance.

Now the important thing about nominal impedance is that it's just that - 'nominal'. It isn't a real value. The magnitude varies hugely across the frequency spectrum. Also, the phase angle varies a lot too, and that affects how current flows.

As manufacturers we have to specify impedance for two reasons:

1. To make sure amplifiers aren't driving a load they can't handle (if too much current flows for a given voltage then components can fail).
2. To give guidance on the max power output the amp can produce into the speaker.

The 10CR250 driver was originally designed as a 6 ohm nominal driver to give a 4 ohm nominal load in a 6x10". However, as we built and measured prototypes we found that the pairing of the 10CR250 and hybrid resonator enclosure gave an unusually 'easy' load. But also the speakers and enclosure result in an extremely efficient system so it produces a lot of output for a given voltage input.

What does an 'easy' load mean? It means that the impedance minima (dips) do not go very low. And also that the impedance phase does not swing in a difficult direction when the impedance magnitude is low. Both these things mean that the output section of an amplifier doesn't find itself having to push more current than it's comfortable with. This meant that we could safely wire two 10CR250 drivers in parallel in our hybrid resonator enclosure and rate this Two10 cab as a 4 ohm nominal impedance. And then the Eight10 can be a 4 ohm nominal cab. etc.

Real versus nominal value - Wikipedia, the free encyclopedia

This post should be sticky'd at the beginning of this thread - or we all could individually bookmark it!
My question is if the Eight 10 is 4ohm what is the Six 10 - to be consistent with the 8ohm driver rating?

 

[BigBobbyBass]

This post should be sticky'd at the beginning of this thread - or we all could individually bookmark it!
My question is if the Eight 10 is either 8 or 2ohm what is the Six 10 - to be consistent with the 8ohm driver rating?

4 ohm

 

[John D Harris]

4 ohm

Sorry, I corrected a miscalculation of the Eight 10 impedance.
The Six 10 cannot be 4ohm - pretty sure.
It's either wired with 3 (wired in series pairs) that are then wired in parallel or a pair of 3 drivers wired in series that are then wired in parallel.
Seems like it would be either 5.22 or 12ohm, but it's late & I could be confused.

 

[Tim1]

Sorry, I corrected a miscalculation of the Eight 10 impedance.
The Six 10 cannot be 4ohm - pretty sure.
It's either wired with 3 (wired in series pairs) that are then wired in parallel or a pair of 3 drivers wired in series that are then wired in parallel.
Seems like it would be either 5.22 or 12ohm, but it's late & I could be confused.

The issue of the ten's speaker impedance has been dealt with in some detail earlier in this thread.

 

[Pbassmanca]

They had a sale on their FB page today . They had a few Prototype 410 @4Ω they were selling. Might want to hit them up before they are gone

Well it makes perfect sense that they have a 410 in a 4 ohm model, as that is probably one of the most useful configurations for most players.

 

[Plutonium244]

Well it makes perfect sense that they have a 410 in a 4 ohm model, as that is probably one of the most useful configurations for most players.

Sure, although any reasonably powerful amp into the Barefaced Four10 at 8 ohms will be plenty for almost any player.

 

[peterpalmieri]

Sure, although any reasonably powerful amp into the Barefaced Four10 at 8 ohms will be plenty for almost any player.

This cab is supposed to be super tube amp friendly and the most popular tube head (SVT) won't run at 8 ohms.

EDIT. I should add the 2 ohm option does fix that

 

[chris_b]

BF cabs are very good at turning watts into SPL so the historical reasoning behind standard cab configs no longer applies.

The SPL of the Four10 is rated at above 131dB. That's into 810 territory, so you don't need to add an extra cab to the Four10 to get as loud as the fridge. With BF cabs you can think differently when planing your rigs.

 

[Mushroo]

An 8 ohm 210 would be pretty sweet. Stack two of them for 410 at 4 ohms.

 

[alexclaber]

Sorry, I corrected a miscalculation of the Eight 10 impedance.
The Six 10 cannot be 4ohm - pretty sure.
It's either wired with 3 (wired in series pairs) that are then wired in parallel or a pair of 3 drivers wired in series that are then wired in parallel.
Seems like it would be either 5.22 or 12ohm, but it's late & I could be confused.

See post #6161 - the bit you've quoted already explains this.

And also this: Real versus nominal value - Wikipedia

Whenever you see loudspeaker or cab impedance quoted as a single number, that isn't the real impedance, it's the nominal impedance.

 

[Tim1]

I have been using my Four 10 with an Ampeg V4b for a while now at band practices. Last practice I took my much loved Ampeg 212av cab for a change. Now I still do rate the 212av very highly but I was surprised by the huge difference between the two. Four 10 has so much more depth, efficiency, fit-in-the-mix and spread. To be fair, it is more expensive but the comparison remains valid. Again, not knocking the Ampeg which is a great match to the V4b and has served me well but the Four 10 is just so much........better.

 

[John D Harris]

See post #6161 - the bit you've quoted already explains this.

And also this: Real versus nominal value - Wikipedia

Whenever you see loudspeaker or cab impedance quoted as a single number, that isn't the real impedance, it's the nominal impedance.

It is my impression that your rating the Six10 at 4ohm is what muddies the waters on what the 10CR250 impedance is.
Unless I'm mistaken there is no formula or wiring that will yield 4ohm (without adding other components to the circuit) with six 8ohm drivers.
I haven't plugged it into the formulas yet, so I could be wrong.
If I'm mistaken, please let me know.

 

[bonin in the boneyard]

I hope someone from Barefaced will chime in (after they've shipped my cab, which is late ) but in the meantime, I can muddy the waters further by mentioning that the ohm designation of a driver isn't as precise as one would think. For example, the difference between 4Ω and 8Ω is significant, but the different between, say, 4Ω and 5.5Ω, is not. I.e., a 5.5Ω driver is essentially a 4Ω driver.

So this is a total guess, but if each driver is 6Ω, then in parallel 3Ω may be close enough for government work to 4Ω, and in series 12Ω is, well, 12Ω. (Just considering the simple case of the switchable Two10.)

I hope someone will straighten me out if I'm off base.

 

[Tugboat]

JUST LISTED.....

For Sale - BAREFACED Super Twin, BAREFACED one10

 

[John D Harris]

JUST LISTED.....

For Sale - BAREFACED Super Twin, BAREFACED one10

 

[John D Harris]

I hope someone from Barefaced will chime in (after they've shipped my cab, which is late ) but in the meantime, I can muddy the waters further by mentioning that the ohm designation of a driver isn't as precise as one would think. For example, the difference between 4Ω and 8Ω is significant, but the different between, say, 4Ω and 5.5Ω, is not. I.e., a 5.5Ω driver is essentially a 4Ω driver.

So this is a total guess, but if each driver is 6Ω, then in parallel 3Ω may be close enough for government work to 4Ω, and in series 12Ω is, well, 12Ω. (Just considering the simple case of the switchable Two10.)

I hope someone will straighten me out if I'm off base.

Yes that is explained in the post Official Barefaced Bass Cab Club that I quoted in #6161 above.
Based on that info the Six10 is actually closer to 4ohm than the Eight10, but that is using two different 'nominal' ratings.
It is REALLY not a big deal, my only point is it is the source of what confusion there has been on this thread & elsewhere regarding the 10CR250's nominal impedance.
Talkbass enthusiasts tend to make mountains out of molehills & that is what this is - SO SHOOT ME!

 

[bonin in the boneyard]

Yes that is explained in the post Official Barefaced Bass Cab Club that I quoted in #6161 above.
Based on that info the Six10 is actually closer to 4ohm than the Eight10, but that is using two different 'nominal' ratings.
It is REALLY not a big deal, my only point is it is the source of what confusion there has been on this thread & elsewhere regarding the 10CR250's nominal impedance.
Talkbass enthusiasts tend to make mountains out of molehills & that is what this is - SO SHOOT ME!

Sorry for missing that and copping a watered-down, less informed version.

Here's the next molehill: I have Mesa Prodigy that I like running in half-power mode. In half-power mode you halve the cabinet impedance when choosing an output; e.g., an 8Ω cab goes to the 4Ω tap.

But what the heck do I do with a 12Ω Two10??

 

[Lowendtech]

Sorry for missing that and copping a watered-down, less informed version.

Here's the next molehill: I have Mesa Prodigy that I like running in half-power mode. In half-power mode you halve the cabinet impedance when choosing an output; e.g., an 8Ω cab goes to the 4Ω tap.

But what the heck do I do with a 12Ω Two10??

Switch it to 4ohm. Can be done.

 

[alexclaber]

Talkbass enthusiasts tend to make mountains out of molehills & that is what this is - SO SHOOT ME!

You're lucky we have very tight gun control over here in the UK or I'd be taking aim right now!

To put it another way, the 10CR250 driver is 6 ohm nominal impedance based on the most resistive section of the impedance curve (through the low mids). However, at low frequencies, where demands are greatest on the amp, its impedance magnitude doesn't dip very low nor the phase swing much in a capacitive direction, especially when in our hybrid resonator enclosures. This means that from a perspective of what amps can handle without having problems it's effectively 8 ohm nominal impedance.

It wasn't planned this way - we designed it to make an awesome 4 ohm Six10 and 12 ohm Two10. But once we looked at the measurements we saw what an easy load it was so did some experimenting and it's turned out to be incredibly amp friendly. Hence we can be very approximate in how we name the nominal impedance of the 10CR models.

 

[GesusBass]

Been 3 weeks since I put my deposit on a super twin this wait is killing me.