Bass cab with frontward AND backward facing speakers?

[Tim Skaggs]

I owned an Ampeg DD-12 / SVR-212 as mentioned by @brianrost in post 6; Bass cab with frontward AND backward facing speakers?

It was very heavy and very underwhelming.

 

[Jeff Scott]

Acoustic made a cab in the 70’s called the 408. 2 front facing 15s and 2 rear facing 15s. that were mounted coaxially. Sounded huge. https://www.talkbass.com/threads/for-sale-vintage-acoustic-408-4x15s-cabinet.940227/

The ACC 408 has two front firing drivers and two drivers in a slot in the middle of the cabinet with up-and-down firing drivers with the theory being the sound from them will shoot out the front.

 

[Jeff Scott]

I could bring up my Maggies but they are stereo speakers (I have, at low levels, run my bass through them), though.

 

[Aidenn7]

Ampeg made the DD-12 and DD-15 cabs with front and back firing woofers. The 2-12 model was over 80 pounds, the 2-15 even heavier.

They usually go for peanuts because of the weight. I bought a DD12 in the late 90s for $200 and sold it because it was too heavy to move around, I can’t imagine moving a DD15.

View attachment 5362652

I have a airhead 212.. but it feels like 50lb.. But I'm use to lifting desk.. and I'm 6'2-230lb. it fits in the front seat of my 2002 dodge neon without issue..

 

[Wasnex]

You’re describing one variant of an isobaric cab design. This is a time tested design that, for my money, isn’t very popular for good reason.

I think the OP is talking about a bipole...the front and back drivers are external.


Dipole top and Bipole bottom

Lows cancel with the dipole because the woofers are out of phase.

Lows sum with the bipole because the woofers are in phase.


Isobaric = Only one of the two drivers is external.

 

[Matthijs]

I once built one with two 10” speakers in a smallish closed cab. The idea was to have a small cab sound like a bigger closed cab. The backfiring one was lowpassed to prevent phasing issues in the lower mid range. This worked and resulted in a lot of super tight bass and powerhandling in a small cab. It also resulted in the heaviest small cab I ever had. It did not last for that reason.

The most interesting part was when I wired it so the higher frequencies ( i think from 2 khz up ) would also come out of the back. This gave a very ‘bose-like’ effect of the speaker not being there. Worked great with upright, made it seem like the sound came out of the bass, not the speaker. But this was very dependent on the room.

So to me it was an interesting experiment, but the pro’s are to specific to be of general use.

 

[bottomzone]

This configuration is fairly common in home audio and some pro audio subwoofers.

 

[micguy]

The low frequencies from a woofer radiate omnidirectionally; where you place a woofer on a box is of little importance in that frequency region, unless...you back the thing up to a wall; in that case a woofer on the back won't work well at all. That's a limitation that may or may not be a showstopper.

That said, the thing that makes bass guitar tough to hear in a band situation is that you usually don't have enough mids and highs pointed at your ears (those frequencies are directional). Taking one of your woofers and intentionally pointing it away from your ears is a step in the wrong direction - it takes one of the weak points of most designs and makes it even worse.

 

[micguy]

I once built one with two 10” speakers in a smallish closed cab. The idea was to have a small cab sound like a bigger closed cab.

That idea, when you get to actually designing a cabinet with real simulation tools, doesn't get you anywhere - the size of the box, the efficiency, and the low frequency limit are a 3 way trade-off - once you pick the two you want, the other one has to suffer. Increasing the number of woofers, or locating them in different places on the box doesn't change a thing in terms of that tradeoff.

 

[retslock]

not sure why anybody would want that, bass amps are not subs

there's no good reason for any speakers in the amp to be pointed anywhere but at the player

For many years I used a Music Man solid state combo that sat on top of an Electrovoice TL 606. I often turned the combo on top to face across the stage for the drummer and others. They liked it that way.

 

[micguy]

You’re describing one variant of an isobaric cab design. This is a time tested design that, for my money, isn’t very popular for good reason.

An isobaric design uses one woofer to create (for the other one) a "bigger" enclosure - at least that's the idea that was put forth. What it really does is create a compound driver, with over twice the moving mass (there's some additional mass in the air tunnel between the drivers), and compensates by wiring the woofers in parallel - you use twice the power to get all that mass moving. It trades off efficiency for size - no breakthrough there.

An isobaric cabinet does not face both woofers out of the cabinet - one is hidden from the outside world. It is a completely different thing that what we're discussing here.

 

[Astronaut]

I don’t know about the benefits of having more or less back play; but this gave me this idea/concept. I play drums, and on stage, the cabs are usually in-line with the drums (hence the term backline) and we, drummers, need monitors to hear the rest of the band because we are not in the sound field. I’m Imagining a cab with side firing auxiliary speakers pointing towards me..

 

[Koog]

The Bergantino HG series has the construction you ask about. I own two HG 310s, and during my gigging years also owned an HG410.

In 60+ years of playing, with extensive stage work, they are hands down the best sounding cabinets I've ever played.

Visit the Bergantino web site to check them out.

Koog

 

[retslock]

I don’t know about the benefits of having more or less back play; but this gave me this idea/concept. I play drums, and on stage, the cabs are usually in-line with the drums (hence the term backline) and we, drummers, need monitors to hear the rest of the band because we are not in the sound field. I’m Imagining a cab with side firing auxiliary speakers pointing towards me..

See comment #30. I've done it that way many times but using a combo and extension cabinet.

 

[InhumanResource]

Ampeg made the DD-12 and DD-15 cabs with front and back firing woofers. The 2-12 model was over 80 pounds, the 2-15 even heavier.

They usually go for peanuts because of the weight. I bought a DD12 in the late 90s for $200 and sold it because it was too heavy to move around, I can’t imagine moving a DD15.

View attachment 5362652

Holy cow, they made combos packed with SVT-II’s? Never seen these before.

 

[MultiScaleMale]

Holy cow, they made combos packed with SVT-II’s? Never seen these before.

That's what I was thinking too. Had to have weighed north of 150lbs.

EDIT: Found the spec sheet - 100 lbs for the 4U 215 and 90 lbs for the 3U 212. An SVT-II is 85 lbs, so an 185 lb combo. We've come a long way.

 

[brianrost]

Holy cow, they made combos packed with SVT-II’s?

That would be pretty heavy, but not as heavy as a T40

It was not a combo in the usual sense, you could buy the cab with no rack, an empty rack or loaded with your favorite Ampeg head.

 

[MegaSwing]

In the 90s, my first attempt at a serious rig was a used Ampeg cab with two opposing 10s powered by an SVT3-Pro. I couldn’t stand the thing. It always sounded overdriven, and it was heavy as a boulder. After weeks of struggle, I took it back to the retailer I got it from and demanded satisfaction.

I kept the amp. He gave me a Mesa Diesel 1x15 straight-up to go with it, and my life was changed forever.

But he clearly was trying to palm one off on me, because that first cab was the absolute worst, and he HAD to know it.

Trust me; at the time I knew nothing about much. What I DID know, even as an amp novice, was that it was a terrible cab, sonically and ergonomically.

 

[Wesley R]

Ampeg made the DD-12 and DD-15 cabs with front and back firing woofers. The 2-12 model was over 80 pounds, the 2-15 even heavier.

They usually go for peanuts because of the weight. I bought a DD12 in the late 90s for $200 and sold it because it was too heavy to move around, I can’t imagine moving a DD15.

View attachment 5362652

I have never seen one of those

 

[Altitude]

The Audiokinesis Changeling cabinets have a rear-firing 3” mid driver that duplicates the front mid driver. The idea there is to spray the back wall with some of the high end to make the cabinet sound a bit more present onstage and less directional.

I have two of the 12” cabinets. The effect is useful if perhaps more subtle than you’d think. They are fantastic sounding bass cabinets in any case.