The Minuet5 in development.

[Clearwave]

I'm working feverishly on the new MTM Minuet5 loudspeaker that will use the very high end Scan Speak 15W4531G woofers and Air Circ tweeter. I can't wait to hear them. Drivers are loaded up, and measurements have begun. I'll post results in this thread so check back often.

Jed

[Clearwave]

The test cabinet is the 8 X 20" MTM curved cabinet by PE:



Baffle Layout:


Next I'll listen to the crossover for a couple weeks and tweak the design to get it perfect. Looks very promising and it's an 8ohm speaker which is nice as well.

[Clearwave]

I decided to modify the crossover once again because the electrical transfer function in the previous design may have resulted in a small peak off axis. And- I wanted to try more of a LR2 with phase correction approach. I've been listening to the speaker for awhile now and the sound is nothing short of breathtaking. The SS6600 is a serious step up from the XT25. It has more clarity, detail, and just sounds crisper and more extended. The Scan Speak mids have a huge sound stage, I can't believe the bass. Even though the speaker will play down to an F3 of around 48-50hz.... it just sounds tight and deep.

More to come... but I should be done with the design in another week. I'll post all the final FR graphs when I'm finished, but right now the measured in room response was +/- 1.5db from 200hz-15k UNSMOOTHED!!!

Jed

[drab]

Very exciting Jed! Just curious though, will you eventually have plans for a square cabinet? I would rather build than buy.

Thanks,

Mike

[Clearwave]

Very exciting Jed! Just curious though, will you eventually have plans for a square cabinet? I would rather build than buy.

Thanks,

Mike

Yes, I have a customer right now that is working on a square version with 1" thick side walls, 1.5" thick front baffle, 3" precision port, and with the driver layout and all other important details exactly the same. As long as the internal volume is the same, the driver layout is the same, etc... the design will perform as designed. In other words it won't matter if the sides are curved or straight.

[Zero the Hero]

Jed whats the sensitivity of these? How does it compare to the M5's? I'm still seriously considering the MTM/sub-in-a-box option, but the price of these seriously cuts into any sub budget, and I honestly wonder if I could tell the difference between these and the M5's. I don't know; I've never listened to high end speakers so it's hard for me to imagine what the differences are and how big they could be.
On the other hand, from what I understand these SS 15's play bass so well I could probably forgo the sub portion and just use my standalone subs...

[Bear]

Jed whats the sensitivity of these? How does it compare to the M5's? I'm still seriously considering the MTM/sub-in-a-box option, but the price of these seriously cuts into any sub budget, and I honestly wonder if I could tell the difference between these and the M5's. I don't know; I've never listened to high end speakers so it's hard for me to imagine what the differences are and how big they could be.
On the other hand, from what I understand these SS 15's play bass so well I could probably forgo the sub portion and just use my standalone subs...

You'd need a much bigger box for the 15Ws to hit serious bass notes. The design models >105dB from my quick Unibox calcs, but it is going to be port-limited in this enclosure. In a 45L enclosure, you are looking at an Fb/F3 of 32 Hz, with a max volume just over 105 dB @ 20W/driver (7.62cm port, btw). Pretty good stuff. Whether or not it gets "muddy" down that low and in a cabinet that big is a different question, though. "Bench racing" only gets you to the art of what's feasible, not necessarily what sounds good.

[Clearwave]

On the other hand, from what I understand these SS 15's play bass so well I could probably forgo the sub portion and just use my standalone subs...

The bass of the 15W is insane to say the least. Best bass from a 5.5" driver and comparable to many 6.5-7" drivers. In 20L, tuned to about 45hz or so you are looking at F3 around 47hz. The thing is, the bass is so clean it sounds like it goes deeper than that.

They are an 8 ohm load and I'm using about 4db BSC. Sensitivity is around 85db 1 watt. I'll have finalized pricing with a few different options this weekend. Crossovers are going to be $250-$600 depending on whether or not you want exotic caps. Obviously that's on the high end of the above figure if using the Mundorf etc.

You can easily get away with not using a sub with this monitor. The bass is THAT good.

Bear, are you sure you are modeling the 15W 4531 G in series? I wouldn't use a pair of these drivers in 45L.

[Clearwave]

Very exciting Jed! Just curious though, will you eventually have plans for a square cabinet? I would rather build than buy.

Thanks,

Mike

Building your own cabinet is a good idea for a reference design. The PE, while pretty, is fairly resonant and will require modification to get it to stop vibrating. I'd recommend Sonic Barrier AND some vinyl based dampening on all the walls. Also, there is a weak spot on the sides where they cut the flange area around the baffle mounting system. It's only 1/2" thick in that area and I'd recommend filling it with poly glue or something to stiffen the cabinet up.

Better yet, build your own cabinet with 1" thick walls, bracing, and 1.5" thick front. I have a customer doing this very thing. Maybe he'll post his drawings sometime?

[drab]

Building your own cabinet is a good idea for a reference design. The PE, while pretty, is fairly resonant and will require modification to get it to stop vibrating. I'd recommend Sonic Barrier AND some vinyl based dampening on all the walls. Also, there is a weak spot on the sides where they cut the flange area around the baffle mounting system. It's only 1/2" thick in that area and I'd recommend filling it with poly glue or something to stiffen the cabinet up.

Better yet, build your own cabinet with 1" thick walls, bracing, and 1.5" thick front. I have a customer doing this very thing. Maybe he'll post his drawings sometime?

Thanks Jed. It would be great if he would post some drawings. Even better would be some pictures documenting his build.

Mike

[Bear]

Bear, are you sure you are modeling the 15W 4531 G in series? I wouldn't use a pair of these drivers in 45L.

See if this looks close to your own measurements:

ScanSpeak 15W / 4531G
Fs 39.50 Hz
Re 3.40 Ohm
Qms 4.60
Qes 0.34
Sd 95.0 cm2
Vas 16.0 l
Xmax peak 6.50 mm
Le 0.25 mH
Le2 0.00 mH
Re2 0.00 Ohm
Nominal Power 20.0 W

Port
No of ports 1
Inside port dia. 7.62 cm
Port area 45.60 cm2
Port end correction 0.519
Standard Design
Vb 20.2 l
Fb 45.54 Hz
F3 48.34 Hz
Port min dia. ! 8.05 cm
Port length 28.83 cm
Design by Vb, Fb and Q
Physical Vb 50.0 l
Absorption, Qa 80
Leakage, Ql 15
Port, Qp 140
Alpha, a 0.629
Vb 50.9 l
Fb 30.00 Hz
F3 29.92 Hz
Response peak 0.33 dB
Peak at 602.56 Hz
Port min dia. 7.32 cm
Port length 26.08 cm
Port 1. resonance 580 Hz

[Bear]

I think the 2.5" Dayton Port from PE is going to have to be the default choice for anyone building small. A 2" port hits a lot of compression issues at moderate volumes, and the 3" port is just too big (>30cm at 40-ish Hertz). Ah, Goldilocks!

Here's my revised Unibox model (what I'm most likely going to build, barring guidance to the contrary):

Physical Vb 22.0 l
Absorption, Qa 80
Leakage, Ql 15
Port, Qp 80
Alpha, a 1.430
Vb 22.4 l
Fb 44.00 Hz
F3 43.25 Hz
Response peak 0.12 dB
Peak at 824.14 Hz
Port min dia. 6.01 cm
Port length 17.39 cm
Port 1. resonance 791 Hz


F10 is in the mid-30s, and that is also when it becomes excursion-limited. Looks like a winner!

[Clearwave]

I like to line the walls with dampening. If you do that you get a mild dip in the bass response with a cabinet that large. Really, you could do 25-35L in a mini tower with these. 50L is pushing it and would require almost no fill. IMO the midrange would suffer as a result in such a large box with no fill.

[Clearwave]

Here's my revised Unibox model (what I'm most likely going to build, barring guidance to the contrary):

Physical Vb 22.0 l
Absorption, Qa 80
Leakage, Ql 15

I'm not sure how compression is audible with a rear firing port- especially a 2" with large flares on both ends. The SPL of the tweeter/woofers will far surpass any "chuffing" noise of a rear firing port.

[Bear]

I'm not sure how compression is audible with a rear firing port- especially a 2" with large flares on both ends. The SPL of the tweeter/woofers will far surpass any "chuffing" noise of a rear firing port.

AFAIK, chuffing and compression/turbulence are related, but differentiated, things. Chuffing is port noise, while turbulence and compression is a diminishment of port function. In other words, a port may get small enough that it can no longer effectively move the volume of air required for the acoustics to work the way that they are supposed to (akin to reaching the Xmech for a driver's throw). Again, all as I know. The rule of thumb that I'm using is based on some work done by the author of Flare-It. I haven't re-done the math to check whether the underlying theory is sound, but Flare-It generally shows that you hit some issues around 20 - 25 m/s, depending upon frequency. Personally, I'd love a more authoritative tool/model, but it is what we have short of me going off to learn Fluid Dynamics.