Looking to build some small speakers that will be used in a 7 channel system. I have 12 Infinity 336545-002 CMMD 4" woofers and 10 Infinity 336417-001 CMMD 3/4" tweeters. Infinity used them in a few different designs but of interest to me is the Modulus ms-1 center channel.
There are numerous options. They'll all involve building cabinets, so there's flexibility. But these drivers are all I'd be using to get down to subs.
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Left Wide, Left, Right, Right Wide - MTM or TMW
Center - MTM or WMTMW
Surrounds - TM, TMW, or two separate TM's for each side
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It's important for this build to stay affordable. I paid a little under $200 CAD for all the drivers, it would be nice to not spend more than $100 on crossover parts, is that a pipe dream? I don't know much about passive crossovers so I'd really be relying on help. Are the Infinity crossovers worth replicating? Improving? Completely changing?
How should I replicate the little waveguide on the tweeters? I'd be CNC or 3D printing them. The throat is 3/4" and the mouth is about 2.5"
Here is what little info I could get on them
Tweeter
I realize the PDF is basically unreadable, but it has a bit of an image of the TM crossover. For whatever that's worth.
There are numerous options. They'll all involve building cabinets, so there's flexibility. But these drivers are all I'd be using to get down to subs.
-----------------------------------------------------------------------------
Left Wide, Left, Right, Right Wide - MTM or TMW
Center - MTM or WMTMW
Surrounds - TM, TMW, or two separate TM's for each side
------------------------------------------------------------------------------
It's important for this build to stay affordable. I paid a little under $200 CAD for all the drivers, it would be nice to not spend more than $100 on crossover parts, is that a pipe dream? I don't know much about passive crossovers so I'd really be relying on help. Are the Infinity crossovers worth replicating? Improving? Completely changing?
How should I replicate the little waveguide on the tweeters? I'd be CNC or 3D printing them. The throat is 3/4" and the mouth is about 2.5"
Here is what little info I could get on them
Tweeter
I realize the PDF is basically unreadable, but it has a bit of an image of the TM crossover. For whatever that's worth.
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You've really got your work cut out for you here.
I assume that there are no TSPs available for these OEM drivers, so those should really be measured.
While the original crossover may provide a good starting point, in the details each crossover is unique to a given combination of cabinet and drivers, and is optimized by means of first simulation and later measurements.
This waveguide business could become fun, too... there isn't that much available to hobbyists in this regard.
The Modulus Center is a better than average design IMHO, as it at least attempts to address the inevitable lobing issues that plague MTMs in the horizontal. I might have placed the mid-woofers even closer together, but at some point is becomes a tradeoff betwen horizontal and vertical dispersion, and vertical may be somewhat more important for centers as they often find themselves in shelves and the like. A design like this actually may not be bad if placed vertically, with symmetrical left and speakers.
With 4" mid-woofers, using two per speaker seems kind of inevitable if you want to get anywhere near sub terrain at a decent level either way. You could certainly try a CB design of a decent size and have boundary gain help you out when wall mounted.
I assume that there are no TSPs available for these OEM drivers, so those should really be measured.
While the original crossover may provide a good starting point, in the details each crossover is unique to a given combination of cabinet and drivers, and is optimized by means of first simulation and later measurements.
This waveguide business could become fun, too... there isn't that much available to hobbyists in this regard.
The Modulus Center is a better than average design IMHO, as it at least attempts to address the inevitable lobing issues that plague MTMs in the horizontal. I might have placed the mid-woofers even closer together, but at some point is becomes a tradeoff betwen horizontal and vertical dispersion, and vertical may be somewhat more important for centers as they often find themselves in shelves and the like. A design like this actually may not be bad if placed vertically, with symmetrical left and speakers.
With 4" mid-woofers, using two per speaker seems kind of inevitable if you want to get anywhere near sub terrain at a decent level either way. You could certainly try a CB design of a decent size and have boundary gain help you out when wall mounted.
Yes, you hit on all the points there.
I think the base case is that I build replicas of the center channel, albeit with a more conventional looking box. Same internal volume. I'll need someone to chime in about the waveguide. Can one follow an OS shape with such a small waveguide?
And yes, I too was wondering about the placement of the tweeter with regard to the woofers. If it should be changed or left the same.
These speakers were one of the first CMMD implementations after the Prelude MTS, with Toole at the helm of engineering. They went for a pretty penny too, so I trust the design was well thought out within it's constraints. The sub that came with them was nearly the same as the one that came with each channel of the Prelude MTS as well.
Unfortunately no T/S to be found.
I think the base case is that I build replicas of the center channel, albeit with a more conventional looking box. Same internal volume. I'll need someone to chime in about the waveguide. Can one follow an OS shape with such a small waveguide?
And yes, I too was wondering about the placement of the tweeter with regard to the woofers. If it should be changed or left the same.
These speakers were one of the first CMMD implementations after the Prelude MTS, with Toole at the helm of engineering. They went for a pretty penny too, so I trust the design was well thought out within it's constraints. The sub that came with them was nearly the same as the one that came with each channel of the Prelude MTS as well.
Unfortunately no T/S to be found.
Dave - You're talking horizontal MTM for center is not good? What do you think about the vertical MTM with that offset little tweeter for sides? I think it's crossed at 2.5k from factory.
tuantran - Thank you! Does that cross at 2.5k like the other one? My last one to figure out is what a TMM would like look with the top driver highpassed and the lower one doing midbass duties.
tuantran - Thank you! Does that cross at 2.5k like the other one? My last one to figure out is what a TMM would like look with the top driver highpassed and the lower one doing midbass duties.
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Not me, i don’t have a centre and if i did it would be one-way. It was Toole who really showed how bad horizontal MTMs.
If i am doing a 2-way XO is rarely above 400 Hz. The tweeter to the side is usually reseved for left right pairs and there will be, in theory at least will have differing dispersion left or right, but probably insignificant. An MT makes more sense with vertical alignment, AFAC an MTM needs a maximum c-c of a 1/4 wavelength at the XO frequency (if you got the spacing that close, a sideways MTM becomes OK).
dave
Crossover of 2.5k is 5.4". CTC spacing between woofers for the infinity design is 6". So no bueno...
Other option is to see how low one can cross the tweeter? I have extra, I guess I could sacrifice. How can I test to see?
But then one asks... Why didn't the original designers just do that? Was it to play it safe for power handling?
Or I just do TMW for everything and WTMW for the center with the tweeter and mid aligned vertically. Woofers of course being the same 4"ers but low passed. I would just need help designing a crossover for that.
Other option is to see how low one can cross the tweeter? I have extra, I guess I could sacrifice. How can I test to see?
But then one asks... Why didn't the original designers just do that? Was it to play it safe for power handling?
Or I just do TMW for everything and WTMW for the center with the tweeter and mid aligned vertically. Woofers of course being the same 4"ers but low passed. I would just need help designing a crossover for that.
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I have a lead on qty(8) 5-1/4" CMMD drivers from a different line for less than $200. Of course no measurements but should I go for it anyway? Then each speaker has one 4" mid and one 5-1/4" woofer to get down to the subs? Center can have one 4" and two 5-1/4". I know this is a bit of a janky build but we can have some fun with it no?
It’s possible, but usually rather difficult. Typically you’d end up with a sub-2 kHz crossover to a 3” mid and perhaps even need to use a small-format tweeter.
Is freq response enough to see if two drivers match up? I'm thinking of buying these 5.25" drivers. They are from the second iteration of the Primus line, mine were from an earlier line, the Modulus and the Entra. I'd be looking to have the 5.25" do a narrow range from about 300 down to subs. Or should I just stick with two 4"? Worried about the midbass band being weak vs complexity of trying to integrate different drivers with unknown t/s.
Picked up eight 5.25" drivers today for $150 CAD.
This is all the info I can really find on them until I take a look at the crossovers they came with.
Infinity 5.25"
Good news is that they are used in a center channel, the PC251 in sealed configuration. They claim to get down to 80hz in that small enclosure.
This is all the info I can really find on them until I take a look at the crossovers they came with.
Infinity 5.25"
Good news is that they are used in a center channel, the PC251 in sealed configuration. They claim to get down to 80hz in that small enclosure.
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I ended up with 2 different styles of 4" driver one CMMD one MMD. A slew of MMD 5.25" drivers, a handful of 6.5" and two different types of .75" tweeters, one CMMD the other MMD, also two different styles of matching waveguides. Also got a few different crossovers that Infinity used with them, 24db slopes, 12db slopes, and different cutoffs.
I tried all the different crossovers, I was mostly comparing the 4" drivers and the .75" tweeters. I then moved on to the digital miniDSP with discrete amp channels. I played around with them for the last few days.
There's one glaring problem... they don't hold a candle to the EMIT tweeters in my other Infinities... I A/B'd them over and over. Those planars are 40 years old, these CMMD's are supposed to be high tech...
Am I doomed to be stuck with planar tweeters? I want to play with waveguides, I have a pair of B&C 250's sitting in the closet with SEOS-12's. Am I going to even like them?
Honestly the 4" mids didn't really stand out against the polydome mids... Technology has marched on from 2" plastic dome mids... I WANTED to like these CMMD's more... And I gave it a few days to get used to them..
The CMMD's did have a certain coherence between woofer and tweeter, prob due to less CTC distance. The polydome and EMIT are a long ways apart, and are crossed high.
I know this is a very subjective post, but humour me. We're here for fun anyway.
I tried all the different crossovers, I was mostly comparing the 4" drivers and the .75" tweeters. I then moved on to the digital miniDSP with discrete amp channels. I played around with them for the last few days.
There's one glaring problem... they don't hold a candle to the EMIT tweeters in my other Infinities... I A/B'd them over and over. Those planars are 40 years old, these CMMD's are supposed to be high tech...
Am I doomed to be stuck with planar tweeters? I want to play with waveguides, I have a pair of B&C 250's sitting in the closet with SEOS-12's. Am I going to even like them?
Honestly the 4" mids didn't really stand out against the polydome mids... Technology has marched on from 2" plastic dome mids... I WANTED to like these CMMD's more... And I gave it a few days to get used to them..
The CMMD's did have a certain coherence between woofer and tweeter, prob due to less CTC distance. The polydome and EMIT are a long ways apart, and are crossed high.
I know this is a very subjective post, but humour me. We're here for fun anyway.
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I find the tweeters a little fatiguing, even harsh at times. I have a theory as to why metal domes are so often found to be fatiguing (aside from breakup modes).
Maybe it's the case that recording engineers...
A) Have poorer high frequency hearing than the average home listener, since they spend most of their days listening to live and recorded music.
B) If they record using soft dome tweeters, or fullrangers. A lot of the work, on a lot of music has been done on auratones. For example most of Michael Jackson's catalogue was, as per the producer.
For both of these reasons it may be the case that they are adding high freq content that metal domes don't damp to the same degree as soft domes. And it just sounds like too much...
Throwing darts in the dark is all I'm doing, having a conversation with myself. It's fine, move along.
Maybe it's the case that recording engineers...
A) Have poorer high frequency hearing than the average home listener, since they spend most of their days listening to live and recorded music.
B) If they record using soft dome tweeters, or fullrangers. A lot of the work, on a lot of music has been done on auratones. For example most of Michael Jackson's catalogue was, as per the producer.
For both of these reasons it may be the case that they are adding high freq content that metal domes don't damp to the same degree as soft domes. And it just sounds like too much...
Throwing darts in the dark is all I'm doing, having a conversation with myself. It's fine, move along.
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