DIY project; Can it be done?

[Geoffcin]

I've recently heard the new Totem Mani-2 Signature speakers, and I just have to have a pair! Problem is that these puppies are not cheap, and with a kid headed off to college in September, my play $$$ is at an all time low. That doesn't stop the fact that I just gotta have a pair of these speakers! Does anyone have an idea about how to trying to reverse engineer these puppies?

[kexodusc]

If memory serves, the Mani-2's use isobaric loading. This isn't exactly easy to pull off right, but shouldn't be too hard with patience and a bit of help.
Totem uses a lot of D-S-T drivers these days, but the tweeter looks like the 1" Seas 27TAFC aluminum dome with chambered back. maybe with a custom faceplate though (probably, but that's okay).

The hard part is going to be getting a pair of the Dynaudio 6.5" 17W75XL woofers that Totem used for this speaker...Unless Totem picked a newer woofer when Dynaudio refocused on speaker manufacturing. Might try a Dynaudio dealer, see if they'll sell you the 2 drivers. Then we need to find the Thiel/Small paramaters for them. Might be available somewhere.

The good news is we know the crossover point is 4KHz electrical, the bad news is we don't know the order. It's quite rare you see a crossover outside (300 Hz to 3 KHz) where our hearing is most sensitive (and where phones cut off I believe) and judging by the woofer, I'm inclined to believe it's a 2nd order slope at that frequency, maybe even simpler.

Geez Geoffcin, for the effort you'd put into this, you could probably build a much easier and better sounding speaker (probably cheaper than this project too). I know the Arro and a few other Totems are popular projects to clone...their drivers are a bit more accessible though. Then again, they're not the Mani-2.

[kexodusc]

Forgot to add, Geoffcin, if you could somehow convince the dealer to let you take these puppies home we could take apart the woofer, and sneak a peak at the crossover...then our problems would be 1/2 way solved...

[Geoffcin]

If memory serves, the Mani-2's use isobaric loading. This isn't exactly easy to pull off right, but shouldn't be too hard with patience and a bit of help.
Totem uses a lot of D-S-T drivers these days, but the tweeter looks like the 1" Seas 27TAFC aluminum dome with chambered back. maybe with a custom faceplate though (probably, but that's okay).

The hard part is going to be getting a pair of the Dynaudio 6.5" 17W75XL woofers that Totem used for this speaker...Unless Totem picked a newer woofer when Dynaudio refocused on speaker manufacturing. Might try a Dynaudio dealer, see if they'll sell you the 2 drivers. Then we need to find the Thiel/Small paramaters for them. Might be available somewhere.

The good news is we know the crossover point is 4KHz electrical, the bad news is we don't know the order. It's quite rare you see a crossover outside (300 Hz to 3 KHz) where our hearing is most sensitive (and where phones cut off I believe) and judging by the woofer, I'm inclined to believe it's a 2nd order slope at that frequency, maybe even simpler.

Geez Geoffcin, for the effort you'd put into this, you could probably build a much easier and better sounding speaker (probably cheaper than this project too). I know the Arro and a few other Totems are popular projects to clone...their drivers are a bit more accessible though. Then again, they're not the Mani-2.

I haven't posted my full review of the HE 2005 show yet, but my choice for "Best in Show" speaker is going to have go to the Totem Mani-2 Signatures. For the modest sized room that they were in, they simply sounded better than any others.

Yes, I think the secret of this speaker is the modified Isobaric loading of the woofers. With tandem 3" voicecoils driving the woofers, the control over them is astounding. We were playing organ music and the whole room was shaking with the bass responce. Truely phenominal bass for such a modest sized speaker!

If it's impossible to get the Dynaudio woofers, is there another company making a similar sized speaker with a massive voicecoil? The SEAS tweeter was sweet, I assume that it's a pretty expensive unit. Can you provide some links to speaker driver manufactures?

As far as the cabinetry; I have access to a state of the art aerospace CNC machine shop, so I am probably going to make the enclosures out of 7075 aircraft aluminum. I would like your opinion on this.

[kexodusc]

If it's impossible to get the Dynaudio woofers, is there another company making a similar sized speaker with a massive voicecoil?

Hmmm...As soon as you said 3" voice coil, the wheels in my head started turning...I remember reading about Dynavox, that made a Dynaudio clone woofer when Dynaudio quit selling drivers to the masses.
Apparently it's specs are identical to the 17w75 woofer (not the XL version with a bit more output and 6Hz lower Fs at 39 Hz as opposed to 45Hz, and by all accounts I've read was built in the same outsourced plant). This would be close to the real Dynaudio driver...

Alternatively, you could use the Hi-Vi Research 6.5" woofer with 3" voice-coil the Totem Forest uses...it's Fs is 43 Hz, a happy medium, and you'd know you're in line with Totem's thinking.

Personally, I'd stick with the Dynavox clone driver...it's not quite as good at the bottom end, but when I plug the T/S specs with the 1.5" or 2" port I get extremely similar numbers to Totem's specs - almost too good to be true numbers:
Internal Volume: 15 L
Fb = 33 Hz (box tuning frequency)
1.5" Port
2 Dynavox woofers in parallel = 4 ohms
Sensitivity: 85 dB
F3 = 28.58 (as opposed to 29Hz for the Mani)
I get a response for the 28.58Hz to 1 KHz, with +1.16/ - 0.1 dB which is pretty good even for a simulation run only.

This is just amazingly too close for coincidence...I think that Dynavox is the perfect clone and the speculation is right!!! I could be wrong but the exact same sensitivity and bass response in a 15L cabinet - that's too big for coincidence. The real Mani would have better power handling at the lower frequencies, but this shouldn't be a problem if you're sensible and not pumping more than 140 watts through them (though they do claim a 200 watt max input, another eerily similar property they share with the Mani).

The SEAS tweeter was sweet, I assume that it's a pretty expensive unit. Can you provide some links to speaker driver manufactures?

The Seas Tweeter is easy, and should surprise you when you see it's cost. As far as I know they only make a few variations of the same 1" aluminum tweeter with chamber...so it rules out pretty much anything else:
http://www.madisound.com/cgi-bin/ind....3340&pid=1024

It's the same one that's in the Forest, and I checked that out this morning at the dealer across the street from my office, definitely the aluminum 1" Seas. $30 tweeter...unless the signature had an upgrade of some sort...let me know. Don't be fooled by the price though...when crossed over really high such as the 4 KHz point in the Mani, you don't always need a super expensive tweeter. David Weems books (and even DIY guru Wayne Jaeschke) all suggest that more costly tweeters are often more espensive just to allow for lower xo points with modest improvement at the top end if any. And $30 tweeters are used in a lot of $2000-$4000 designs. I've only heard this tweeter in the Forest as far as I know but it sounded quite nice. The Mani-2 might have had some custom mods, but you're not going to get those if it did. The good news is the crossover should allow for a good degree of flexibility for attenuating or boosting the tweeter to your liking. I haven't checked, but I'm thinking you'll definitely need some compensation circuitry to tame the midwoofer's response peak at (again, coincidentally ) 4000Hz...it might take care of itself though depending on the order of crossover, which might be quite steep.

Once you get into designing an xo to mimic this, you're gonna need more than my help...I'll be the first to admit crossovers aren't my strong point, I can do a decent crossover, but I'm no pro. A good crossover isn't too hard, a great crossover takes alot of experience, and I expect the Mani-2 has a pretty good crossover. Not to worry, there's plenty of people with nothing better to do who would like to see you pull this off.

As far as the cabinetry; I have access to a state of the art aerospace CNC machine shop, so I am probably going to make the enclosures out of 7075 aircraft aluminum. I would like your opinion on this

Well, internal volume is key here. Totem claims they veneer the inside of the cabinet. I don't know the density of aircraft aluminum, but, you want something that is fairly dense and sturdy (which I'm sure it is), but also gives off the acoustic energy like wood or MDF...I have no idea if the aluminum you'd use does or doesn't. Remember, speaker cabinets don't have to withstand turbulence and maintain high-stress structural integrity. My gut feeling is to stick with MDF, but this is your project.

Looking at the drivers, and some early modelling, I can't guarantee this would be an exact clone, (you never know until you try) but I have no doubt that you'd end up with a pretty great sounding little bookshelf that could easily hold it's own with $2000 speakers and probably much, much better for under $500 in parts if nothing else.

[Geoffcin]

You da man Kexo!

You've got me fired up for this project now! I've already got an idea about how to make an Isobaric chamber to mount the two woofers. I'l draw up some plans on my CAD/CAM program and email you over a sketch.

Re; aluminium. Yes, I could still use MDF, especially if I can CNC machine it to spec like aluminium. The real thing is that I like the idea of having a unique speaker, and my ability to machine aluminium would be something nobody ever seen before, at least homgrown. I did get to hear the Piega speakers where are aluminium, and they were outstanding.

[kexodusc]

I think aluminum would be absolutely great if it works. Would it be metallic to look at or painted in a high gloss or something? Unfortunately, I just don't have the knowledge in my head to be able to predict the impact on sound. I have a few articles at home that evaluate various densities/thicknesses of MDF, HDPB, birch and oak plys etc, there are noticeable affects to altering the material, but that's not to say aluminum won't work.

Normally I'd just say "try it and tell us", but again, I have no concept of the cost of buying the aluminum or how much work would go into creating the cabinets. If it's not too bad, do it. If it doesn't sound great, build some MDF cabinets.

You've got a few options on how to proceed. The easiest would be preserve the width and driver spacing of the front baffle, and internal volume, leaving you some flexibility for machining whatever looks you want.
Or just start from scratch, since we don't know the crossover design anyway, and we can tailor the xo to your cabinet. But then you're moving away from a Mani-2 clone to a whole new design. Nothing wrong with that, as long as it's in line with your goals. Might be a bit harder though.

[Geoffcin]

Started the design already!

[kexodusc]

Looking good...have you figured out how you'll mount the interior woofer?
I think the trick is to use a 1/2" or slightly thinner MDF or aluminum cross brace.
Using a 0.75" material for walls, I plug the internal volume of the Mani-2 at 18 litres, leaving plenty 3 litres for the driver displacement and some cross-brace/mounting. That should be plenty, though we'd have to do some displacement tests on the actual woofer and magnet.

Totem uses borosilicate damping material...safe bet you're not going to get access to that for cheap. A bit of polyfill or acousta-stuff should be fine.

[Geoffcin]

Looking good...have you figured out how you'll mount the interior woofer?
I think the trick is to use a 1/2" or slightly thinner MDF or aluminum cross brace.
Using a 0.75" material for walls, I plug the internal volume of the Mani-2 at 18 litres, leaving plenty 3 litres for the driver displacement and some cross-brace/mounting. That should be plenty, though we'd have to do some displacement tests on the actual woofer and magnet.

Totem uses borosilicate damping material...safe bet you're not going to get access to that for cheap. A bit of polyfill or acousta-stuff should be fine.

I've really got to get the drivers and get some good measurments so I can build the isobaric chamber. Then I'l be able to design some bracing.

I might be able to get some of the acoustic damping material that's used behind the avionics panels in military aircraft.

[kexodusc]

I've really got to get the drivers and get some good measurments so I can build the isobaric chamber. Then I'l be able to design some bracing.

I might be able to get some of the acoustic damping material that's used behind the avionics panels in military aircraft.

I wonder if these speakers will sound best at 30,000 feet?

Just be careful with the amount of damping material, you'd be amazed at how big a difference just a bit can make, especially at the bottom end. It's often a trial and error thing.

Geoffcin, you've GOT to put fins on these.