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NCD Barefaced One 10


jimbartlett
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Just picked up another One 10 from those lovely people at Barefaced in Brighton. Got it home, tried it through both my Tace heads along with it’s twin. Sounds bloody great!! I can’t believe the bottom end on these things. I play Ska and Reggae, this setup handles it no problem.

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Yep, whenever you add a second matching cab you get more output across the whole sonic spectrum (no surprise) but they couple at lower frequencies so you get even more in those frequencies.

If you want to hear how this happens and you have a hi-fi with stereo speakers, pick one speaker up and move it right next to the other speaker (so they couple at lower frequencies). Hear how the sound changes? Basically it gets fatter!

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Sorry, but you don't get more output across the whole sonic spectrum. While you do get additional output in the lows, in the mids and highs you get lots of cancellation, and the frequency response gets tilted towards the bottom end. This is why adding more cabs can be good when you have a box that is shouty and lacking in bass - a description that applies to a lot of small bass cabs. (I'm not referring to the Barefaced 10 specifically, as I've never heard one).

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[quote name='stevie' timestamp='1507206806' post='3383910']Sorry, but you don't get more output across the whole sonic spectrum.[/quote]

Except you do. Leave all the knobs in the same place, plug a second cab in and twice the power flows due to the halving of impedance, so you get more output across the whole spectrum. And with the cabs stacked vertically most of the inevitable cancellations are not problematic (anything you lose through narrowing of the vertical pattern tends to be offset by the benefits of the increased stack height).

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Alex, I said nothing about whether the cancellations were problematic; I just said they were there and you seem to agree that they are inevitable. But if there are cancellations, summing cannot be consistent, which makes frequency response uniformity impossible. It should be obvious why that matters.

The gain you get from doubling cone area and power is frequency dependent - that’s true. When two cones are closely coupled (up to a quarter wavelength apart) you will get an extra 6dB in output. However, the theory also states that two drivers a half wavelength apart will cancel and cause comb filtering due to the different arrival times of the sound sources. The frequency and depth of these peaks and dips will vary depending on where you (and your audience) are standing. You cannot simply ignore this: it is important.

One of the Adamson user manuals provides the formula for what happens when you use two 8” drivers together:
“In this example we show two mid frequency drivers. The acoustic centres are 8” apart. If we use the same formula as we did on the 18” driver,
8” = .66 feet
1130/.66 = 1696Hz
1696Hz /2 – 848Hz
we can calculate the maximum usable frequency. This time it allows a maximum of 848Hz. Anything above this frequency will result in interference when listening off axis.”

I went into my workshop, stacked two fullrange 12” systems and measured the results. As expected, the pair was 6dB louder than the individual systems at low frequencies. However, above 600Hz or so the responses were extremely uneven, the peaks and dips changing dramatically with every step I took. This is the response on axis and 1.5 metres away from the top cabinet (red one cab, green two cabs):



This is the response 30 degrees off axis, level with the top of the top cab (red one cab, green two cabs):



In both cases you can see the half wavelength cancellation at around 700Hz and the peaks and dips above. What’s interesting is that the output from the top cab on its own (red) is greater at the measuring position between 400 and 1kHz than when it is used together with the bottom cab (green) – despite the extra power going into the system. Of course, this is only two points in space, but it should be enough to show what I am talking about.

So how serious is this interference between stacked drivers really? Alex says that “most of the inevitable cancellations are not problematic”. It doesn’t look like that to me, and some speaker designers think they are serious enough to take measures to mitigate them.

JBL’s JRX225 2x15 + horn PA cab is one example. This is how the blurb describes it:
“A ‘Quasi 3-Way’ design offers the extra bass for which a dual fifteen system is designed, but without sacrificing performance in the critical mid-range. The upper woofer produces mid-frequencies and bass, while the lower woofer concentrates on bass only. The reduction in mid-range phase cancellation greatly improves midrange sound quality and coverage.”

JBL clearly thinks it’s problematic - otherwise, why bother?. Peavey thinks so too because they do the same thing. Then there is Community, dB Technologies, Cerwin Vega, Wharfedale, Bose – and that’s just from a quick google.

And yes, let’s not forget Barefaced! Its 2x10 uses exactly the same technique of rolling off one driver to prevent them from interfering with each other in the midrange. I quote: “Both drivers in the Two10 work in unison to produce big bass and punchy mids but to improve dispersion only one has treble output - just like a PA line array........ By only letting higher mids and treble come from one speaker we get much better dispersion through those frequencies so you have more consistent tone around the stage and venue.” Which is more of less what JBL says.

It seems that Alex agrees with me after all. :)

Edited by stevie
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Thanks for your detailed post Stevie, much of which regrettably goes over my head. Could you explain how this relates to the subjective reports from the OP and others (me included) that stacking a couple of One10s produces a much more enjoyable sound than using one on its own? (Sorry mate, on re-reading this it comes across as a bit flippant - which it's not meant to be. I'm just trying to understand.)

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Yes but do those graphs actually represent a realistic situation? What happens when you compare one cab on the floor vs two cabs stacked on the floor, with the mic located variously at the bassist's ear position, the band mates' ears positions and the audience's too?

If all you care about is the tone that you hear and don't need to fill the room with sound (and don't really want to hear your sound in the context of the room) then yes, one speaker running within its limits and pointing directly at your head (and with all room boundaries well away) will give you more even response than two.

But figure in what happens in the room for everyone, especially a bassist who isn't eight inches tall (that's about how low on-axis is for a single One10), and things are very different.

We low pass filter one driver on the Two10 (and continue that with its bigger siblings) because they're side by side. Vertically stacked drivers combine well in the real world - there's a reason line-array PA systems are so popular!

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[quote name='stevie' timestamp='1507313761' post='3384754']
Sure! It's as Alex described: in its simplest terms, you get a bass boost that fattens the sound up.

I do try to keep my posts as jargon-free as possible, but sometimes you can't avoid it.
[/quote]

Thanks, and no criticism of your 'jargon' content intended btw. I find all this stuff about speakers/cabs interesting and am trying to increase my understanding if it.

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[quote name='alexclaber' timestamp='1507314674' post='3384767']
We low pass filter one driver on the Two10 (and continue that with its bigger siblings) because they're side by side. Vertically stacked drivers combine well in the real world - there's a reason line-array PA systems are so popular!
[/quote]

Alex, there appears (to me anyway!) to be a contradiction in what you say. With a multi-driver set-up, you state that a vertical arrangement works better than a side-by-side one - which I get. However, fitting two sets of rubber feet to your multi-driver cab's suggest that they are designed to be used in either orientation; in fact, the orientation of the 'Barefaced' logo on the Two10 cab suggests that it's actually intended to be used on its side - hence the need for a low-pass filter on one driver. But then, why do your 12" multi-cab's, which are obviously meant to be used vertically (emphasised by the placement of the BF logo) still have a low-pass filter on one driver? Why don't you just specify that all your multi cab's should be used in vertical orientation (obviously keep both sets of rubber feet for storage purposes) and do away with the low-pass filter?

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Guest bassman7755

[quote name='scrumpymike' timestamp='1507375397' post='3385025']
the orientation of the 'Barefaced' logo on the Two10 cab suggests that it's actually intended to be used on its side - hence the need for a low-pass filter on one driver. But then, why do your 12" multi-cab's, which are obviously meant to be used vertically (emphasised by the placement of the BF logo) still have a low-pass filter on one driver?
[/quote]

AFAIK only the x10 cabs have the filters.

[quote]Why don't you just specify that all your multi cab's should be used in vertical orientation (obviously keep both sets of rubber feet for storage purposes) and do away with the low-pass filter?[/quote]

I think the idea is that the x10 cabs are more aimed at those wanting a traditional looking (as well as sounding) stack e.g. stacking 2 2x10s into a modular 4x10 (and without the horrid dispersion characteristics of a typical 4x10).

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I don’t understand all the technical jargon I’m afraid but I’m pleased everyone has started a conversation about the cabs.

Just an update after a rehearsal. Absolutely bloody amazing the pair of these. I play in a 6 piece Ska band and these sounded HUGE. Everyone kept looking at them and shaking their heads in disbelief.

Now just to let you know what I do with the tone to get my sound, have a Trace and do boost the low band on the EQ including the low mid but cut the high mids then level off the high band to centre. I also cut the passive tone on my P Bass a tad too.

I’m chuffed. Thanks Alex and Barefaced!

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[quote name='bassman7755' timestamp='1507385593' post='3385128']
AFAIK only the x10 cabs have the filters.

[/quote]
Quote from one of Alex's earlier posts on this thread:

"We low pass filter one driver on the Two10 (and continue that with its bigger siblings)..."

I take that to mean the 2 x 12" cab's.

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