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astrojet 25th January 2018 07:39 AM

mid-tweet for a 12pw mltl
Hi all.

This is probably more a question for Chrisb than anyone else, as he's heard all the drivers in question. Happy for all opinions though.

I have built one of Dave's/Scott's MLTL designs for a 12pw. I really enjoy it. I'm now going to rebuild it in some fancy local hardwood, using the 12pw crossed over to one of a) MAOP 7.2, b) FF85wk, c) Alpair 5.2. I already have the MAOP and FF85wk and like them both. I've read many of the arguments about pairing 2 wideband drivers. I'm actually very interested in being able to miniDSP compare a very wide range of xover frequencies and slopes.

1/4 wavelength c-c spacing with the FF85wk and 5.2 would afford higher ideal xovers of ~500Hz or greater. I could probably get the MAOP7.2 close enough for ~400Hz. Although, I'm not at all convinced that I need something this low. Perhaps I enjoy the beaming of the 12pw when run full range. Perhaps I also enjoy midrange from larger drivers. These are the types of questions I want to experiment with by having such a huge frequency overlap in driver responses.

Any thoughts on which might be better? These will be biamped with tube amps. Listening space is about 4.5m X 3.5m X 2.75m opening onto a larger room. I sit about 3m from the speakers and listen to all kinds of music at moderate to low volumes.

I'd put them in closed volumes of: MAOP 3 litres, ff85wk and 5.2 about 1.5 litres.

Thanks for any thoughts everyone!

planet10 25th January 2018 07:50 AM

If you have the A7 MOAP i’d be inclined to use it, I wouldn’t use it in the small a volume thou. The others are good 2 but the MOAP is really special (you must have the 2nd pair in North America — i bought Chris’ off him and well get to spend some serious time with them).

The 2 smaller drivers also deserve more volume.

But with any of them i’d try fitting a midTL… sucking th eentire back wave away opens things up.

On the other hand, knowing the ML-TL you are building, a roundish bowl with a flat-lip from the Dollar Store would be much easier to implement sub enclosure (damp it with ductal.


astrojet 25th January 2018 04:29 PM

Thanks very much Dave. How much volume would you use for the MAOP midTL? If I pushed it off to one side just above the 12pw, do you think it would take too much volume away from the 12pw MLTL?

As an aside, I very much like the aspect ratio and appearance of the tall cabinet. I'm not very tempted to fold it.

planet10 25th January 2018 07:17 PM

In the wide and shallow twin ML-TL the midTL does not take up too much volume, in a single driver ML-TL it probably would. A 4” chunk of PVC from front to back with the A5.2 or FF85 would probably be OK. And a creative person could taper that pipe (probably easier with a cardboard tube).

I have stuggled with this before… in particular in how to get a mid+tweeter (or midTweeter) close to the B139 in my tapered triangulated TL. The most practical solution is to just add a pod on the side of the TL but getting that to be visually acceptable is a challenge.

You want to target a midTL of at least the volume of a Q=0.58 sealed box, but larger is OK, you are not trying to extend the bass response, you want room for sufficient damping to eat the entire back wave. Looking at my sims this is probably an impractically large volume, so as big as you can live with.


astrojet 26th January 2018 05:10 AM

Thank you for the input Dave. I need to stop and think about this before I start making sawdust!

chrisb 26th January 2018 09:00 PM

Don't want to shout, but DEFINITELY the MAOP. Dave's original layout for the MTM didn't leave quite enough room to nest the tapered TL for the mid-tweet between the dual 12PWs, - as much of a struggle as it may be for him to conceptualize / draw some of his brainstorms, let me tell you that building them can be quite the challenge. (Facets :mad:)

If a simple, larger diameter straight pipe could model well enough, that'd make the build substantially easier.

astrojet 27th January 2018 06:16 AM

Thanks Chris. I don't know what to do now. I really dig the audio presence of the 12pw in the tall mltl and it would be nice to move the MAOP back into the main room. They are now in fh3 in the bedroom.

Perhaps I'll build a couple of pairs, the 12pw in the mltl and sacrifice a bit of space for the ff85wk, and another WAW/FAST with the MAOP and something fancy for the lows.

I know there have been tons of threads on what woofer to use in a WAW, but I'm still left wondering, mainly because I dig the mltl 12pw so much. I wouldn't mind dropping a fair amount of cash on some nice woofers to pair with the MAOP if anybody had a suggestion that would be as lively and easy to listen to as the 12pw but allow close c-c spacing with the fullrange and fit into a space my wife will dig. ~50L should be no problem. I am fine with complicated woodwork if the design works.

Dave, you've already helped me out for free with both the 12pw mltl plans and fh3 plans and I'm grateful. If you'd like to move this conversation to the commercial side of your business, I'm happy to do so. I'm willing to drop a fair amount of cash into drivers and a design if you or Chris have any suggestions.

Hope everyone is having a fine weekend.

planet10 27th January 2018 08:55 AM

2 A12pw? The ML-TL is 140 litre thou, and the A12pw doesn’t go nearly as low sealed, but a pair would fit in 40 litre.

There is an SB 10” woofer i was looking at for an FHXL sealed deflector. You could fit 2 and a midTL in not much more than 50 litre i figure. Enuff swept volume and sealed to take it as low as you have power for.

I was going to do a Tysen XL (working title) for 2 of these & an A10, but A7 would make it slightly smaller.

They might have an 8” that would work as well.

I have already done up a design with 2 ScanSpeak 7”, it is 75 litre but illustrates the possibilities.

email me if you want to take this further.


chrisb 1st February 2018 05:57 PM

AJ - having built numerous non-monkey coffin enclosures including both the original Tysen with single SDX7, and the V2s with dual drivers similar to the tilted parallelogram version in Dave's sketch above, I can advise that the latter seems to have the best WAF .

Jstainton18 18th June 2018 02:56 AM

I was toying with a similar design but replacing the a7.3 a 12pw paired with a revelator tweeter and replacing the pair of scanspeaks with sb acoustics sb17nrxc35-8. I haven't done all my math yet, so i wouldn't be surprised if it doesnt work lol but would gladly value any input you guys would throw at me!

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