WAW / FAST MTM MLTL crossover point/s

eaglears

Member
2012-07-23 5:37 am
Evening Gents

Is it possible to have a FAST MTM MLTL speaker using two 6.5" woofers with a small fullranger and vary the crossover point depending on music played, say if using the MA 7.3, from 120 to 320 hz allowing one to optimize for the genre of music being played or does bsc have to be built in to the design thus determining physical dimensions resulting in only one crossover point that works?

Thanks,

Sheldon
 

eaglears

Member
2012-07-23 5:37 am
Thanks for the response Dave. I'm also interested in using the ff85wk and if so then have two PLLXO wired up that I change up maybe one at 200 hz and one at 350 hz plus for example.

And here are the woofers I was thinking of. Do their specs look appropriate for this application? I think I would have more fun with the 6.5's but perhaps the 5" sb's would better match the ff85wk?

https://www.madisoundspeakerstore.c...coustics-sb15nrxc30-8-uc-5-paper-cone-woofer/

https://www.madisoundspeakerstore.c...-acoustics-sb17nrxc35-8-uc-uncoated-cone-6.5/
 
Thanks for the response Dave. I'm also interested in using the ff85wk and if so then have two PLLXO wired up that I change up maybe one at 200 hz and one at 350 hz plus for example.

One of our PLLXOs has 160 on one side and 240 on the other.

We tried the FF85 at 180 but upped it to 240 in the FASTs using Peerless 830870.

And here are the woofers I was thinking of. Do their specs look appropriate for this application? I think I would have more fun with the 6.5's but perhaps the 5" sb's would better match the ff85wk?

I hear good things about the SBs, but haven't tried or modeled them. The near 10 dB peak up high could be a problem -- we are working on dealing with a similar peak in some ScanSpeak Illuminators (our design, but not our project).

We usually choose woofers that have a smooth roll-off up top.

Our next FF85 FAST (Tysen V2) is using push-push Silver Flute W14 in a ML-TL. We are going to see if we can get a passive XO for these.

dave
 

eaglears

Member
2012-07-23 5:37 am
"One of our PLLXOs has 160 on one side and 240 on the other."

Sorry Dave I didn't understand, could you please elaborate on the above.


If using the sf w14 in fast ff85wk mtm mltl...

Would it have enough output in the low 40's? Isn't the max a bit weak on these w14's? Is their fs low enough to be used without a sub for music with any convincing spl? If I want a dynamic speaker should I really be looking at using 6.5" woofers?

If wanting to use a subwoofer for heavier genres/pipe organs at 50 hz down then could this be wired in to the PLLXO. Could this be done in such a way as to benefit the w14's by relieving it of the lowest frequencies as what's done with the ff85wk's? Would using a sub solve the dynamics issue of using smaller 5.5" woofs vs the 6.5's?

Could the speaker be built tall so that the ff85wk was at 38" ish high?

Is it possible to have the ff85wk in it's own enclosure within the speaker to enhance its performance and have it not be affected by the woofers?

Do you think a fast mtm mltl with ff85wk + st w14 would image well considering the cross over point would be as low as 180 for girl and guitar and a Max of 320 or 350 for symphonics? I'm assuming that some of the criticisms of mtms imaging are due to cross over points at 1800 hz and higher.

Would the mltl be compromised because there are two woofers and only one can be at an optimal height? How would this affect the sound vs one driver in a mltl?

When using a PLLXO is 3 octaves of cone behaviour enough so say crossing at 350'hz the driver just has to behave to 3000 hz then it doesn't matter past that point? I'm still trying to understand why the sb's wouldn't work well here. If the sf w14 are comparable in performance then the cost savings would go a long way towards a dayton rs 12 woofer to go from 50/60 hz down to 20 so I'm not married to the idea of using the sb's.


Gracias,

Sheldon
 
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Sorry Dave I didn't understand, could you please elaborate on the above.

We have our PLLXOs mounted in the plastic housing from an external Macintosh floppy disk. On each side, 6 RCAs (2 each, in, LF out, HF out) wired together with a PLLXO.

If using the sf w14 in fast ff85wk mtm mltl...

Would it have enough output in the low 40's? Isn't the max a bit weak on these w14's?

The standmount MTM is tiny (13 litres) and gets into the 50 Hz range, the push-push floorstander has a slow roll-off and is close to 30 Hz.

Tysen-V2-extents.gif


Is their fs low enough to be used without a sub for music with any convincing spl? If I'm a bit of a bass head should I really be looking at using 6.5" woofers?

Good bass but they aren't going to pressurize your chest, but 6.5s aren't likely too either. Althou our A12pw MTM (below) does generate a fair amount of bass.

If wanting to use a subwoofer for heavier genres/pipe organs at 50 hz down then could this be wired in to the PLLXO. Could this be done in such a way as to benefit the w14's by relieving it of the lowest frequencies as what's done with the ff85wk's? Would using a sub solve the dynamics issue of using smaller 5.5" wolfs vs the 6.5's?

Sure. Yes. A proper 3-way. Doing a bandpass with a PLLXO might be a bit tricky.

Could the speaker be built tall so that the ff85wk was at 38" ish high?

Pretty close to that already… and with the tilt-back.

Is it possible to have the ff85wk in it's own enclosure within the speaker to enhance its performance and have it not be affected by the woofers?

A must.

Do you think a fast mtm mltl with ff85wk + st w14 would image well considering the cross over point would be as low as 180 for girl and guitar and a Max of 320 or 350 for symphonics?

The FF85wKeN images like crazy if the information is present in the software.

I'm assuming that some of the criticisms of mtms imaging are due to cross over points at 1800 hz and higher.

Yes. Centre-to-centre is less than a ¼ wavelength at the crossover.

Would the mltl be compromised because there are two woofers and only one can be at an optimal height?

In ours, both woofers are at optimal Zd. But if you are doing an MTM as long as the average is Zd you are OK… like having a big oval woofer.

A12pwMTM-veneer.jpg


When using a PLLXO is 3 octaves of cone behaviour enough so say crossing at 350'hz the driver just has to behave to 3000 hz then it doesn't matter past that point?

Should be. More important in the midwoofer than in the midTweeter.

I'm still trying to understand why the sb's wouldn't work well here.

I didn't say they couldn't. You may have to deal with the 10 dB peak to keep it from intruding. With the illuminators our 1st suggestion is a passive notch.

If the sf w14 are comparable in performance

Not having heard the SBs i can't really comment.

dave
 

eaglears

Member
2012-07-23 5:37 am
Thanks for the info Dave. Looks good so far.

I should have been clear at the start but I was hoping to have the drivers front firing with the mid tweet in the middle like a classic d'appllito configuration.

If doing this is it still possible to have the mid ff85wk in its own enclosure and the w14 optimized for mltl?

Why in your 12pw + 7p do you have the 7p offset?

Do you find with side firing woofers that there is discontinuity past 80 hz as Scott has discussed below? Aren't the benefits of more point source behaviour more beneficial than those of a push push woofer? How about d'appito configuration but push push so there are two woofers firing out the back as well as the front?

http://www.diyaudio.com/forums/multi-way/63930-woofer-side-firing-pair-vs-front-firing.html

Thanks,

Sheldon
 
Sheldon - I think Dave's goal with the offset configuration on the A12PW/A7 MTM was to get the drivers' c-t-c spacing as close as possible to permit playing with a wider range of XO pointed than might otherwise be possible. This is much like we did a couple of years ago with FF85K and dual EL166/ woofer 6 . Both pairs proved to be much easier to draw than to build - the wide bezels on the Alpairs add particularly to the "fun" with the internals. When I get involved with fibre-glass & resin on a pair of enclosures, photos are the last thing on my mind. Suffice it to say - tight MF-ing fit

I am currently working on a bespoke system build with separate enclosures for FF85WK and dual Silver Flute SW14s, in a configuration inspired by Paul Carmody's Tarkus, and also have the first proto build of the Tyson V2 as shown in Dave's sketch sitting on my basement hallway ready to fire up for listening evaluation. Since my Onkyo surround receiver's digital XO/ bi-amp function is actually faster to set up than the PLLXO / dual amps, it'll probably get that treatment first
 
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eaglears

Member
2012-07-23 5:37 am
I like the looks of the Tysen V2 plans, good WAF, nice slim profile, optimized MLTL and push push woofers. I bet their midrange imagining will be awesome. The only thing that throws me off is the side firing woofers as the d'appllito configuration appears better as frequencies are directional above 80 hz but I trust Dave and Chris's judgement and if they say this set up sounds good then I believe it. Dave mentioned he thought Thysen II could be crossed higher than 240 hz 1st order, any idea to where? How low could Tysen II be crossed?

Once the Tysen V2 and the Tarkus inspired build are done I'd love to hear thoughts on how they both compare sonically to the tight MF-ing 12pw + 7p mtm you guys built.

Sheldon
 
Sheldon - these latest 2 designs aren't our first builds with the FF85WK and combinations of 2 or 4 mid-woofers per enclosure, (usually side mounted) and we've played with XO's as high as the low 300Hz range (320 - 330 seems to ring a bell?)

The Silver Flutes are a helluva bargain, but after living with the big MTMs for a couple of months before rotating the more WAF friendly A10P compact floorstanders back into the system*, I kinda suspect the dual 12PW in MLTL will deliver more impact and extension in the deepest bottom end.

* in doing so, a pair of "assignable" amp channels were freed up to run front height effects channels, which I honestly find adds a lot to the sense of space.
 

eaglears

Member
2012-07-23 5:37 am
The 12pw look lovely but are out of my price range. Thank goodness for products such as the 85wk's and w14's in the marketplace.

At this point I'm interested in the build and sonic differences between the mtm with side firing woofers vs front firing mtm. I'd like to hear feedback on differences in coherence and sound stage. When Chris says the front mtm is a tight MF-ing fit l'll assume it's a hard build.

Sheldon
 
The 12pw look lovely but are out of my price range. Thank goodness for products such as the 85wk's and w14's in the marketplace.

At this point I'm interested in the build and sonic differences between the mtm with side firing woofers vs front firing mtm. I'd like to hear feedback on differences in coherence and sound stage. When Chris says the front mtm is a tight MF-ing fit l'll assume it's a hard build.

Sheldon

Any updates on this ??
How low does these go ?
How does this compare with fhlxl or mltl with alpair 10.3?
 
That'd be a better question for Aaron - and I'm pretty sure he could give a sufficiently geeky reply. As I think Dave would consider the circuits to be "proprietary", all I can say is that the last 3 higher order passive networks Aaron designed worked very well indeed, and while Dave is certainly correct about cost advantages of simple order PLLXO/ bargain class D amp - I'm running exactly such in my wife's upstairs system - that's an approach that is simply anathema for some folks.

Of course, if there was a "best of both worlds" approach, it would probably be something along the lines of minidsp / active , which can include either simple or elaborate room correction.

edit: and as alluded above, while a pair of A12PW per side are very competent, even stock the Silver Flutes deliver more than you'd expect from a driver at 1/6 the cost.
 
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