Barefaced impedence switch

[chris_b]

[b] Now that is interesting. . . . .[/b]

[b] [url="https://www.facebook.com/BarefacedAudio/?hc_ref=ARTQXZQHrvB2omkDdn4v_uyAT8MoNITkCHGln_oy4F7cyKD0aACdRdfPNxk8vOxeI5c&fref=nf"]Barefaced [/url][/b]

[b] [url="https://www.facebook.com/BarefacedAudio/?hc_ref=ARTQXZQHrvB2omkDdn4v_uyAT8MoNITkCHGln_oy4F7cyKD0aACdRdfPNxk8vOxeI5c&fref=nf"]Audio[/url][/b]

[url="https://www.facebook.com/BarefacedAudio/photos/a.10150125091062704.324333.130257677703/10155805170787704/?type=3"]1 hr[/url] · [url="https://www.facebook.com/pages/Brighton/112710045409378"]Brighton[/url] ·

We've bloody done it! Switchable impedance Two10. 4 ohm when you're using it on its own, 12 ohm when you want to make a stack. Just flick the toggle switch on the back!




[url="https://www.facebook.com/BarefacedAudio/photos/a.10150125091062704.324333.130257677703/10155805170787704/?type=3"][/url]

[dannybuoy]

I've always thought something doesn't quite add up with these cabs.

If the higher value is 12 ohms, that suggest the speakers are 6 ohms each, which results in 3 ohms when wired in parallel. That's all fine and dandy if your 4-ohm capable amp is actually pretty happy at 3 ohms. But then if you add a second cab you have 1.5 ohms, which might be pushing your luck when it comes to 2-ohm capable amps, no?

Since my amp is ok at 2 ohms, I'd be happy with a pair of 4-ohm cabs, and carry a serial wiring cable in case I ever ended up rig sharing and someone wanted to use their 4-ohm capable amp with my cabs (which would give them a 8 ohm load, or 6 depending on if the above were true or not!).

Edited October 3, 2017 by dannybuoy

[TimR]

You'd have to look at the impedance/frequency plots to be sure of that.

It says that the impedance isn't quadrupled as you'd normall expect when switching from parallel to series wired.

Would Alex have had some custom speakers wound with tap-offs or something equally as clever?

[Conan]

[quote name='dannybuoy' timestamp='1507033984' post='3382871']If the higher value is 12 ohms, that suggest the speakers are 6 ohms each, which results in 3 ohms when wired in parallel.
[/quote]

Assuming there are no other resistors in the switching circuit. I am no electrical engineer, but I imagine that this could be done quite simply?

[dannybuoy]

It would be simple if it were just those two drivers involved, but you require a different crossover when switching between serial and parallel, hence why it's taken them so long to come up with a method of doing so!

Edited October 3, 2017 by dannybuoy

[leftybassman392]

At first glance I read the thread title as 'Barefaced impudence switch'...

[fftc]

[quote name='dannybuoy' timestamp='1507033984' post='3382871']
I've always thought something doesn't quite add up with these cabs.

If the higher value is 12 ohms, that suggest the speakers are 6 ohms each,
[/quote]

But isn't the One10 8 ohms?

[chris_b]

How does he do it? I really don't care. . . . as long as the cab is light, loud, makes a great noise, is flexible and modular then I have an interest.

More flexibility is always a good thing and a flexible good thing is pretty good in my book.

[TimR]

[quote name='Conan' timestamp='1507039742' post='3382939']


Assuming there are no other resistors in the switching circuit. I am no electrical engineer, but I imagine that this could be done quite simply?
[/quote]

Not without wasting power.

[scrumpymike]

[quote name='fftc' timestamp='1507044583' post='3382993']
But isn't the One10 8 ohms?
[/quote]

Yep

[TimR]

Doing the maths you can't have two loads that when in parallel give 4 and when in series give 12. There is some smoke and mirrors going on.

In the past Alex has explained that the impedance of drivers isn't 4ohms or 8ohms, those are just approximate DC resistances. As soon as you put a frequency through them the impedance changes and is usually much higher. I'm guessing that it's high enough at most of the frequencies we are concerned with to make no odds.

.

Edited October 3, 2017 by TimR

[Merton]

I have a feeling the original 12 ohm cab and 4 ohm cab have the same driver but with different impedances, but I could be wrong and it doesn't really answer how the switch works.

(Remember the 10" driver was originally developed for a 4 ohm 6x10, hence it's a non standard impedance).

[CameronJ]

*sigh*

This has only fuelled my recent GAS for a Two10.

[LewisK1975]

I also read on that facebook posts that they plan to make the modification available as a kit, like they have by selling dedicated 4/12ohm looms for those wishing to change their cabs impedance.

They just need to work out how best to make it easily DIY'able for current two10 owners.

I know I'll be interested when they do make it available in kit form.

[Kev]

Hmm, sounds like an expensive accidental knock of a switch waiting to happen...hopefully that has been thought through!

[Happy Jack]

[quote name='Kev' timestamp='1507123466' post='3383466']
Hmm, sounds like an expensive accidental knock of a switch waiting to happen...hopefully that has been thought through!
[/quote]

No, to reach the switch first you have to pull off the handle.

[Happy Jack]

[quote name='TimR' timestamp='1507051390' post='3383043']
Not without wasting power.
[/quote]

Luckily enough, modern bass amplification is simply [i][b]awash [/b][/i]with surplus power.

[chris_b]

. . . . and people are posting like they know more about this stuff than Alex does! Jeeez!

[charic]

[quote name='chris_b' timestamp='1507125878' post='3383488']
. . . . and people are posting like they know more about this stuff than Alex does! Jeeez!
[/quote]

Makes for a good conversation though doesn't it!

[TimR]

[quote name='chris_b' timestamp='1507125878' post='3383488']
. . . . and people are posting like they know more about this stuff than Alex does! Jeeez!
[/quote]

Can't see anyone who has done that.

Alex's post on Facebook says it's 'Magic' which seems a dubious claim to me.

[Conan]

[quote name='TimR' timestamp='1507128945' post='3383512']Alex's post on Facebook says it's 'Magic' which seems a dubious claim to me.
[/quote]

Or the subtle use of marketing speak by a businessman trying to sell his products? Surely he is entitled to do that on his own FB page?

Better get these guys reported to trades descriptions too. Unless there is voodoo in their choccies...

Edited October 4, 2017 by Conan

[TimR]

I'd be more concerned that they don't actually deliver their chocolates by dropping men from helicopters and via speedboats as is clearly shown in their advertising.

It's very misleading.

Edited October 4, 2017 by TimR

[dannybuoy]

So until Alex straightens us out, my best educated guess is this.

If I hook up two '12 ohm' cabs in parallel then my amp should see 6 ohms.

If I hook up two '4 ohm' cabs in serial then my amp should see 8 ohms.

However both configurations would result in the same wiring (two parallel chains with each having two in series), the actual load [b]should [/b]be the same for both of the above.

So I can only guess that we're looking at 7 ohms per driver, making the cabs either 3.5 ohms or 14 ohms in reality. In which case hooking up a pair of 4-ohm Two10s would give your amp 1.75 ohms, which should (hopefully) be within tolerances?

[TimR]

No. As I said above the nominal impedance is only nominal. Between 30hz and about 10khz the impedance will be higher. Typically an 8ohm speaker might be around 32ohms across the mid range frequencies.

He says he's developed a crossover and if there's a loom that fits existing cabs then he is using his standard drivers.

Might be splitting the very low frequencies between the drivers via the crossover.

.

Edited October 4, 2017 by TimR

[Dood]

There is a crossover that will have some loading effect on the circuit. Taking the Two 10 as an example, only one speaker receives the full range signal (via the crossover), the other is treated by the crossover to sculpt it's output response. I expect that Alex is able to use the effects of the crossover on the circuit to assist in the switching arrangement. I've not seen the schematic to say for sure how it's working exactly.

Edited October 4, 2017 by dood