Detuned 2x12 = Rock!!!

gproud · Post by **gproud** » Thu 07/20/06 7:58 pm

So I've always read about taking 2 speakers out of a 4x12 for a 'detuned' cabinet, but never thought doing it to a 2x12 would be as good. Well, I have a 2x12 Avatar with an H30 and V30 in it, and I've been wanting to try it with just the H30 for a while with my 18 Watt TMB. So I took the V30 out last Friday before my gig. I get there, and the first set is always kinda of lighter music, then we kick it in around 2/3 the way through the first set. My singer, who never usually notices or comments on my guitar sound, turned to me after we did an AC/DC song and goes 'Did you get another new amp?' I just laughed and said 'No'. He goes 'S**t man, your guitar sounds awesome tonight'. The drummer and bass player concurred, so I explained on set break what I did with the cabinet. They didn't understand, but they all agreed it made the amp sound a lot more full. And it does. Using the 30 Watt H30 was going to improve the sound anyway, but having the empty speaker hole just opened my tone wider than it's ever been. If anyone has ever thought about doing this, give it a try. 100% better sound for me. Just thought I'd share.

archtop · Post by **archtop** » Thu 07/20/06 9:19 pm

So, is it a closed back cabinet?

Arlajo · Post by **Arlajo** » Thu 07/20/06 10:41 pm

Phsyconoodler showed me a similiar thing with one speaker taken out of a 2 x 10 cab. I agree. It sounded awesome. I'm going to build a 2 x 12 cab and only put one speaker in it. I'm convinced.

Post by **Plexi** » Thu 07/20/06 10:57 pm

Yes this works very good.. You can also use like half a speaker cutout..or kinda large rathole or halfmoon looking thing on each side. Wich would be about the same size as half of a 12" speaker hole.

Richie

rollingelbow · Post by **rollingelbow** » Thu 07/20/06 10:58 pm

Interesting.. and then you always have the option of popping the speaker back in should you require it for recording.. so how about 2 2 x 12 cabs but one with the H30 and the other with the V30..... probably equally as killer... recording anyway.I like this idea because if i build a 2 x 12, i may not be able to afford 2 speakers off the bat

jetson · Post by **jetson** » Thu 07/20/06 11:12 pm

i believe that just removing a driver rom a 2x12 cab just ports it.
i dont like it. does it work? yes. noe what????????

rollingelbow · Post by **rollingelbow** » Thu 07/20/06 11:27 pm

We still have to find out if it is a closed or open back cab.

dancindave · Post by **dancindave** » Thu 07/20/06 11:30 pm

pretty sure its closed otherwise the port wouldnt make much of a difference...i think..

Francis_Vaughan · Post by **Francis_Vaughan** » Fri 07/21/06 3:22 am

This would indeed seem to be another example of a fourth order vented system. A simple hole will act in the same manner as a vent, the end effects means that the effective length of the vent isn't zero even though the hole is only cut in the baffle. The diameter of the vent (being speaker sized) will make for an unusual final effect.

Importantly it is not hard to model the bass alignment changes this modification will create. What is harder to model are the effects due to wave cancellation. These will run all over the spectrum, from loss of low bass due to simple loss of baffle, through to weird phase anomalies as the energy rattles about inside the cabinet before being beamed out of the hole to combine with the front wave.

Again, it is a pity Celestion don't provide the Theile-Small parameters of their drivers, then this would be a simple exercise to plug the numbers in.

Knowing the dimensions of the cabinet would be worthwhile.

Post by **zaphod_phil** » Fri 07/21/06 5:45 am

AFAIK the "detuned cab" is another KoC invention. I'm not sure what real physics theory basis it has, if any. Apparently, it's just as case of taking a closed cab and yanking one or more of the speakers out. Great claims are made for them, and maybe they do really work. There are one or two speaker cab companies around that specialize in building these - for example see http://www.vintone.com/detuned.html

If you scroll down, you see this quote from KoC, "What's the best cabinet design? Something between a large sealed cabinet and a slightly smaller but still large bass reflex design: a "detuned" cabinet with a single driver. This is essentially a cabinet built for two identical drivers with one driver left out and it's mounting hole left open. The port is not tuned to any specific frequency but instead allows a broad range of frequencies to be reversed through the shallow duct. Instead of having a brick-wall bass roll-off, the low end rolls off gradually but slightly slower than the raw driver. The large cabinet does not sound boxey so mids and highs sound three dimensional, unlike a sealed cabinet which sounds comparatively sterile. We sometimes call this an "open-front" design since it is like having an open-back cabinet where you bring along your own wall. The closed back gives consistent sound regardless of room placement; therefore the port cannot be on the back. The only caveat is one that applies to every other design: that elevating the cabinet seriously reduces low frequency output, so -always leave it on the floor."

gproud · Post by **gproud** » Fri 07/21/06 6:05 am

Yes, it's an Avatar 2x12 closed back cabinet. The regular size, the G212H Special. Dimensions are 21"H×28½"W×12½"D.

Post by **Plexi** » Fri 07/21/06 6:35 am

AFAIK the "detuned cab" is another KoC invention

I think KOC must be related to Al Gore.

Richie

PCollen · Post by **PCollen** » Fri 07/21/06 7:10 am

zaphod_phil wrote:AFAIK the "detuned cab" is another KoC invention. [/i]

I didn't know that the Knights of Columbus were into music gear.

Anyway...I recently purchased an Avatar open-back G212H with the H60/H30 combination (2 x 16 || = 8 ohm) . It has a very thick, rich bottom end..more so than I am used to from the 1 x 12 Boogie cab I was using (sold it) such that I have to dial down my MAZ-18 bass to about 3 and run the Cut half-way to keep the 'spank' of my Strat's low E-string (.046). My intent is to replace the parallel second output jack with a DPTP switch to allow me to select either one of the speakers independently (@ 16 ohm load) or the pair together as delivered (@ 8 ohm load)...3-in-1 capability, as the situation dictates.

Cathode_Ray · Post by **Cathode_Ray** » Fri 07/21/06 7:33 am

Francis_Vaughan wrote:This would indeed seem to be another example of a fourth order vented system. A simple hole will act in the same manner as a vent, the end effects means that the effective length of the vent isn't zero even though the hole is only cut in the baffle. The diameter of the vent (being speaker sized) will make for an unusual final effect.

Importantly it is not hard to model the bass alignment changes this modification will create. What is harder to model are the effects due to wave cancellation. These will run all over the spectrum, from loss of low bass due to simple loss of baffle, through to weird phase anomalies as the energy rattles about inside the cabinet before being beamed out of the hole to combine with the front wave.

Again, it is a pity Celestion don't provide the Theile-Small parameters of their drivers, then this would be a simple exercise to plug the numbers in.

Knowing the dimensions of the cabinet would be worthwhile.

What he said...

Cathode_Ray · Post by **Cathode_Ray** » Fri 07/21/06 7:42 am

Why not make a "cover for a front port, with the ability to vary the opening - i.e. tune it. As opposed to an openback cab(which radiates all over the stage and helps the rest of the musicians) a front port is sending more energy out front. Also reinforces the speaker wave at many frequencies. Distance from the opening to speaker and the size of opening would be important.
Most cab tuning is intended to smooth response over a broad range as well as help dispersion a bit. But for a guitar it's probably more benificial on low-end. Think of it as a variable subwoofer.

Post by **zaphod_phil** » Fri 07/21/06 8:01 am

If you look at what Kevin O Conner proposes, it seems much less scientific than that. Just use an oversized sealed cab, with one or two extra speaker openings without the speakers installed. Supposedly this creates a "detuned" cab and takes you to tonal Nirvana, regardless of the speakers' Thiele-Small parameters or the exact dimensions of the box and apertures.

Heck, maybe it even works!

Post by **Plexi** » Fri 07/21/06 8:46 am

I built an 18 head for a friends studio,and he had a small 1x12 cab for it..but also made a detuned 2x12 type cab. We played through both,and it seems to add some thickness or better bass end. And it was nice and loud too.

Richie

gproud · Post by **gproud** » Fri 07/21/06 9:11 am

Wow. I never thought this thread would generate so much interest. That's what I love about this place. The knowledge base is overwhelming. All I can tell you is, people other than me noticed a big difference in my sound, which I attribute to detuning the cab and running the 18 watt through the 30 watt speaker, instead of a 30 watt and 60 watt speaker.

geekmacdaddy · Post by **geekmacdaddy** » Fri 07/21/06 9:52 am

rollingelbow wrote:I like this idea because if i build a 2 x 12, i may not be able to afford 2 speakers off the bat

That sure hits home! I'm bout to order an SS cab off ebay, and this 1/12 thread is pleasant and practical surprise.

dartanion · Post by **dartanion** » Fri 07/21/06 3:42 pm

I have been running my Ambrosia Maple offset 212 cab as a detuned unit for about a year and it still amazes me. Single 30W Blue Dog 16ohm, and it is really loud. Sounds really cool with my EL34 SE.

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Detuned 2x12 = Rock!!!

Detuned 2x12 = Rock!!!

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