Rogers AB3A clone for the LS3/5A

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hornwannabe

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Joined 2014
#1
Rogers AB3a clone for the ls3/5a


Hi! Got a vintage Rogers LS3/5a in transit, I’ve heard this speaker before and they have excellent mids but are lacking in the critical 60-80hz bass region for kick drums.

Came across the Rogers Ab3 and I don’t think the price tag is justified ($4000++ WTF).
ROGERS AB3A

I do like the idea of of a bass unit that can also serve as the stand of the LS3/5a since my space is quite limited but due to the size of the driver it can accommodate it would be a stretch to call it a subwoofer. That is okay though since I would just like to hear a proper kick drum and don’t feel the need for subterranean lows nor high spl since the Rogers are not amenable to being driven to deafening levels.

So. Is it worth it to clone the AB3a?

Seems doable as I plan to make a passive version with and just have a minidsp and a Plinius SS amp to drive them. I can probably track the B110 woofers via ebay and have a carpenter build out the sealed cabinets.


But it says on the Rogers site that it’s a “special” doped version of the b110 woofer (doubt it) to give it bass.


So my question is: with the AB3a dimensions (H 23.62” x W7.48” x D6.5”) would I be better off just using a more modern woofer in a sealed enclosure or should I just stick to using two pairs of B110 woofers like the ab3a.

Any driver or build suggestions? Would want to maintain the dimensions for aesthetics and space and the thin wall sealed construction of the AB3a


Thanks!


PS: Also aware that the plans for the AB1 passive (the ported one woofer predecessor of the AB3a) are floating in the internet and that is also an option, but I think I will have better luck with a sealed implementation to integrate it better to the LS3/5a for when I want to listen to rock music.
 

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#2
The big hump above 100 Hz makes the LS3/5A hard to integrate with a subwoofer. Active flexible crossover like the minidsp would be usefull.
Regarding the woofers. Sure why not make them suitable as stands for the LS3/5A. Modern 5" woofers>/subwoofer drivers 3 or more drivers per cabinet.
 
#4
IIRC the woofer was another B110. They culd not get anything else to timbre match. They might add some more speaker dope to push the resonance down to get more bottom (at less sensitivity). Easily diyable.

So yes, $4k seems to have a lot of rarity/vintage value in it.

Falcon seels a pair of brand new B110 for £225 (ouch), but used ones are fairly common.

dave
 
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#9
And available on your side of the pond? No idea.

I’d recommend a pair of Silver Flute W14 in a push-push ML-TL, but the cost of shipping would likey exceed the cost of drivers — only available at Madisound AFAIK (husband). Really good for the dollar, does F10 anechoic of <35 HzL and you can make it a stand.

dave
 
#12
Well, if I ever get LS3/5as again, I'll definitely get (or make) some AB1s. Is the AB3a better? I don't know, I haven't heard it. But I know the AB1 is an incredibly clever solution, which works really well in its intended application. Part of its success is the passive crossover, (just one cap and one coil, feeding both drivers), taking the strain off the LS3/5as midwoofer, and creating an excellent blend. Plenty of people have tried to marry a more conventional sub with the LS3/5a and failed. Trying to clone the AB3a with different drivers sounds quite optimistic. You might get lucky, but you might not.

(I gather thst the woofers in the AB3a are B110s with added mass. But the added mass appears to involve a large dust-cap type addition on the cone.)
 
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#14
planet10 said:
Here is the basic plan: https://frugal-phile.com/boxlib/SF-W14-ML-TL-191213.pdf

Double the cross-section (change shape as required), and vent, couple the magnets together.

dave
Click to expand...
You call this an ML-TL design - I'm a little hazy on what that means. It appears to be a columnar ported box, with the port very much at one end. So the pipe resonance of the columnar box is part of the design?

The AB1 is not a simple ported box, but a coupled cavity. All the coupled cavity designs I have owned or heard over the years (principally a number of KEFs, as well as the AB1) have had very good subjective bass quality.

(Mind you, I did own a Harbeth stand/sub once, a sort of AB1 clone for the HL-P3. It didn't work nearly as well as the AB1, to my ears.)
 
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#15
hornwannabe said:
Also looking into the ab1 but thinking that a driver update might be needed. But the plans are floating around so might stille be an option
Click to expand...
Why might a driver update be needed? The B110 is still in demand after all these years for a reason. And the AB1 design depends on the fact that it uses the same driver as the LS3/5a.

PS Regarding you comment in the first post about kick drums - one of my very clear memories of the LS3/5a and AB1 combo (it was almost 30 years ago!) was that kick drums sounded very good. My room was not huge, at the time - a 3m by 3m study- and I wasn't looking for huge volumes. But it did work well in that context. (The album Stars by Simply Red sticks out in my memory for the kick drum sound. Which is rather embarrassing. But it was the 90s!)
 
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#16
I know that not everyone who has tried AB1s has as positive an opinion of them as I do. But they really worked well for me. Maybe the small room, near field setup was part of it. Also, I suspect they only really blend properly with 11 ohm LS3/5as.
 
#17
ianbo said:
You call this an ML-TL design - I'm a little hazy on what that means. It appears to be a columnar ported box, with the port very much at one end. So the pipe resonance of the columnar box is part of the design?
Click to expand...

Yes. All tall skinny tower enclosures are ML-TLs not reflex enclosures. A reflex assumes a slug of air, a box not to far from a cube. As one dimension becomes significantly greter than the others the box transitions from a reflex to a mass loaded transmission line.

Anyone using a reflex modeler to model a tower box will not get accuarte results.

ansys-ml-br-compare-gif.733699


Realizing we have an ML-TL and not a reflex the placement of the driver and vent can be optimized to take full advantage of the quarter-wavr resonance to extend the response downward.

dave
 
#19
planet10 said:
Yes. All tall skinny tower enclosures are ML-TLs not reflex enclosures. A reflex assumes a slug of air, a box not to far from a cube. As one dimension becomes significantly greter than the others the box transitions from a reflex to a mass loaded transmission line.

Anyone using a reflex modeler to model a tower box will not get accuarte results.

Realizing we have an ML-TL and not a reflex the placement of the driver and vent can be optimized to take full advantage of the quarter-wavr resonance to extend the response downward.

dave
Click to expand...
Thanks, I've read up a bit more now. I see that the theory comes from Martin King. I've seen threads recently where similar designs were dismissed as poorly designed ported boxes, but there's clearly more to it than that.
 
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