Just bought a pair of Focal Profil 77s for $60 (23 years old with rotten foam surround on both tweeters). I plan to replace the tweeters with a pair of Seas T35 that I have on the shelf. I will of course build new crossovers.
The 77 is originally a 2.5-way, but most commercial MTMs I know of are 2-ways (Wilson Cub, Dunlavy sc1, Lipinski 707, Snell lcr7, Revel gem, Focal mini utopia).
What do you think? 2-way or 2.5-way? (there's a lot to find about MTMs on the net, but I have yet to find a good explantions on the pros and cons on 2-way vs 2.5-way).
The woofers are Focal 7V413 Polyglass.
The 77 is originally a 2.5-way, but most commercial MTMs I know of are 2-ways (Wilson Cub, Dunlavy sc1, Lipinski 707, Snell lcr7, Revel gem, Focal mini utopia).
What do you think? 2-way or 2.5-way? (there's a lot to find about MTMs on the net, but I have yet to find a good explantions on the pros and cons on 2-way vs 2.5-way).
The woofers are Focal 7V413 Polyglass.
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The main benefit of 2.5 way is the relative ease with which you can do baffle compensation. Otherwise, you can still get basically the same result as 2 way.
In the case of an MTM, the main difference will be something else... how many mids will there be working in the crossover region. Each option is going to depend also on why, and which way you would do an MTM.
In the case of an MTM, the main difference will be something else... how many mids will there be working in the crossover region. Each option is going to depend also on why, and which way you would do an MTM.
... I have yet to find a good explantions on the pros and cons on 2-way vs 2.5-way..
Here you go my friend..
(1) The issue with 2-way MTMs in detail.
(2) A solution to the above issue i.e. 2.5way MTM, by Charles Hughes.
(3) A simpler version of (2), for non-technical people.
All the best.
AllenB said:Each option is going to depend also on why, and which way you would do an MTM.
Sir, an elaborate explanation of the same would help a lot of people out here, the OP (possibly) and myself included. Thanks.
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Wow, thanks Virus, haven't seen those before. Very interesting. And they illustrate exactly what is worrying me with a 2-way MTM config: the cancellations between the two midwoofers (not the usual MT vertical lobing problem). Even if you sit far away and on-axis with the tweeter, the floor/ceeling reflections and power response must be all over the place? This surely must be audible?
And, yes, easy BSC was my first though as well.
Below: vertical dispersion of five 2-way MTMs and one 2-way MMT (all Stereophile).
And, yes, easy BSC was my first though as well.
Below: vertical dispersion of five 2-way MTMs and one 2-way MMT (all Stereophile).
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And for the MMT only angles from -15° to +10° are shown, it seems ...(...) and one 2-way MMT (all Stereophile).
Even if you sit far away and on-axis with the tweeter, the floor/ceeling reflections and power response must be all over the place? This surely must be audible?
I think there's some difference between an MTM with a horn and that with a tweeter when it comes to such things (not sure though). Still, the M-M nulls should occur in either case, except for small mids where the distance could be smaller. It's said that an attentive person would be able to notice the nulls the moment he stands up from his seated position.
I've liked both ways.
mtm was 2 x 5" with 3.5" ribbon crossed maybe 3-4khz (optimus cs5 lineaum)
tmm was 2 x 6" with big frame tweet crossed at 1,750hz (morel solstice kit)
I suppose if you want a speaker to pass the sit down / stand up test, neither would pass...
mtm was 2 x 5" with 3.5" ribbon crossed maybe 3-4khz (optimus cs5 lineaum)
tmm was 2 x 6" with big frame tweet crossed at 1,750hz (morel solstice kit)
I suppose if you want a speaker to pass the sit down / stand up test, neither would pass...
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I suppose if you want a speaker to pass the sit down / stand up test, neither would pass...
I guess the sit down / stand up test is not that important at all. If someone wants to actually listen then he has to sit in the sweet spot anyway. If the stereo is running in the background then the absolute frequency response doesn't matter that much unless it becomes really crappy.
When I stand up the sound looses some brightness but this is mainly due to the "tweeter" that I use. But a very interesting side-effect is that the phantom sources remain on the height of the tweeters when I stand up.
Regards
Charles
Djk (rip) felt listening to a mtm was like listening to music from down a pipe.
Since the phase timing is way off anyway, i don't see the ceiling bounce vs side wall bounce at 10' away that important.
Maybe if i had 3 exact cone area crossover point driver speakers, mt, tmm, and mtm, then i could make a judgement.
But it is a difference if you care about it i guess.
Oh yea, i also had a tmm, double 15's crossed to big horn at 750hz.
And yes, at 10' highs came from horn.
But did not bother me.
I'm all about the bass !!!!!!!
Point source would be nice, but it is all about the tradeoffs.
Since the phase timing is way off anyway, i don't see the ceiling bounce vs side wall bounce at 10' away that important.
Maybe if i had 3 exact cone area crossover point driver speakers, mt, tmm, and mtm, then i could make a judgement.
But it is a difference if you care about it i guess.
Oh yea, i also had a tmm, double 15's crossed to big horn at 750hz.
And yes, at 10' highs came from horn.
But did not bother me.
I'm all about the bass !!!!!!!
Point source would be nice, but it is all about the tradeoffs.
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I guess the sit down / stand up test is not that important at all. If someone wants to actually listen then he has to sit in the sweet spot anyway.
Even I was thinking somewhat along those lines. On the whole, it may not be as bad as we think as on-axis seating (main lobe) should not be a problem. Besides, there are several studio monitors in this format and below are the measurements obtained from one such model, the DMS-1, for example.
JBL DMS-1 Experience and Measurement
- Home
- Loudspeakers
- Multi-Way
- MTM, 2-way or 2.5-way ?