There are jigs for box joints. Now, if he did them all using hand tools only, then we are talking.
Either way, airtightness might still be an issue with this type of joint, he probably sealed the inside edges. If the enclosure gained stiffness over, say, a much simpler rabbet joint, then the additional effort might actually be worth it.
Of course it is larger, the original box design is centered around optimal placement for the mid and treble to such an extent that the 12" really is in the wrong spot and in a too small volume. The sweet spot for the 12PR320 is around 110 liters, making the original box a few cm extra wide and deep gets it close, however you still usually end up with a tuning that may cause some issues around 40Hz. Increasing volume a bit more and pushing FS lower moves the problems to a frequency where it is less likely to be noticed. Believe it or not, the ports themselves are almost the same.
If you want to make the OSMC better than everyone else it is easier to do a sealed box and make a sub for the low end, personally I think that is a waste because it is perfectly possible to make a good 3 way speaker to cover the same or more range.
I'm sorry @mbrennwa , did not intend to go there again...
I see your point about the volume, but what would be the correct placement of the woofer?
Closer to the centre, a possible alternative I was thinking about was if one could orient the box sort of horizontal like some studio monitors. Mid and treble like they are and the 12" next to them to the side, this could reduce the issue a fair amount, get the box just a few cm bigger in two directions and it would be easier to get a good tuning compromise as well.
This is an unusual placement for the woofer, wouldn’t this cause lobing along the horizontal axis? I know studio monitors can be like that but the use case is very particular.
I don't think it should cause any issues, the xo is really low for this 12", I see diffraction as a bigger issue but as long as the mounting is flush the change in diffraction should be minimal.
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Another option I tried voicing was to put the port next to the mid, away from the edges.
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Another option I tried voicing was to put the port next to the mid, away from the edges.
I don't take it personally.
I believe you sometimes tend to forget the design constraints we established for the OSMC. These constraints did not come out of the blue, but were determined using a poll before diving into the design process. The details are in the first post of the main OSMC thread. There's no point in nagging about the size/volume of the OSMC box. It's simple: if the OSMC does not tick you boxes, look elsewhere (no pun intended 🙂).
Good to know. I appreciate your effort in this, it was a demanding process.
IMO the design criteria and volume would be easier to optimize if it was for a 10".
I agree that the constraints given during the initial phase were quite limiting, not to say unrealistic given that the end goal was a sort of "ultimate yet attainable" design, which is why I decided to drop out because these limitations made sure that the best performance was impossible to achieve.
Fairly certain I even suggested going down to a 10" as well, but the poll decided it should be a 12" so...
IMO the design criteria and volume would be easier to optimize if it was for a 10".
I agree that the constraints given during the initial phase were quite limiting, not to say unrealistic given that the end goal was a sort of "ultimate yet attainable" design, which is why I decided to drop out because these limitations made sure that the best performance was impossible to achieve.
Fairly certain I even suggested going down to a 10" as well, but the poll decided it should be a 12" so...
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Judging from all of this, it seems that the best OSM Tower using a 12pr320 would be a cube (ouch 🙂 ) of 125 liters, That volume will reduce to be close to 110 liters (give or take) by the time you add serious bracing, woofer, perhaps a chamber for the crossover to be able to access it from behind, damping material and port tubes. Tune that at about 30Hz (or what suits your room/taste the best) and be done with it. I like what Gabo did, especially since one can make the upper cabinet/baffle as wide as midrange/tweeter combo need it, and keep the bass cabinet separated. Cube would bring a strong standing wave to the table, but it is predictable and higher in frequency than tower so probably easier to deal with either by absorption or by lowering the crossover point between woofer and midrange. Woofer, being close to the floor, would benefit a bit from boundary reinforcement and deal with floor bounce quite well. Front baffle for bass cabinet could be tilted few degrees back so direct sound can be enjoyed by the ones that chase that thing : )
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Correct.
Or you can stuff the port and make a proper sub, I suggest double 12" in separated chambers if you chase a certain aesthetic, single 18" if you want bang per buck and slightly better quality.
Or you can stuff the port and make a proper sub, I suggest double 12" in separated chambers if you chase a certain aesthetic, single 18" if you want bang per buck and slightly better quality.
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My only comment about the 12pr320 is... That's a bad *** driver, especially for the price. We may not have achieved the bass extension some would like, but it really sounds good and delivers incredible SPL.
For what it's worth, the studio I built these for does have Subs, two of them. They are crossed very low and do as much for tweaking a couple of low end room modes as anything. For just general listening, many times they turn the subs off, the speakers sound fantastic without the subs.
But the "secret sauce" of these speakers, if there is such a thing, is the mid-range driver. That's about as good a mid driver as I've ever heard. We've compared these to a pair of Revel F328Be's and they compare very favorably. The Revel's maybe a tad bit more refined in the high end, but not as good for the studio application these were designed for.
For what it's worth, the studio I built these for does have Subs, two of them. They are crossed very low and do as much for tweaking a couple of low end room modes as anything. For just general listening, many times they turn the subs off, the speakers sound fantastic without the subs.
But the "secret sauce" of these speakers, if there is such a thing, is the mid-range driver. That's about as good a mid driver as I've ever heard. We've compared these to a pair of Revel F328Be's and they compare very favorably. The Revel's maybe a tad bit more refined in the high end, but not as good for the studio application these were designed for.
Troels’ 12” Faital speaker has a similar volume as the OSMC, it’s the same driver. He has this to say about volume:
So looks like even 70 litres work fine, with going larger yielding only a small benefit.
You are not looking at the full picture, group delay for the tuning is not part of his equation, which is the whole point for me, though that is more the symptom than the cause. And he has a large space to use them in, one of the original criteria for the OSMC was flexibility in terms of room placement IE bookshelf or stand (though this criteria went out the window for some reason).
Besides, this is NOT the OSMC thread, this is the thread for the larger tower adaption.
If you do not have any interest in a different design and/or tuning for the OSMC there is no reason to respond here.
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Besides, I am fairly confident that mr. Gravesen made his design as a slightly lower cost alternative to the OSMC.
Besides, this is NOT the OSMC thread, this is the thread for the larger tower adaption.
If you do not have any interest in a different design and/or tuning for the OSMC there is no reason to respond here.
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Besides, I am fairly confident that mr. Gravesen made his design as a slightly lower cost alternative to the OSMC.
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@maximax77 ,
Troels is abstracting it from an Excel Specsheet from SanSpeak... it is a sim with perhaps the less precise tool existing... It is highly inacurate, you can just believe his measurement that are gated in room above 300 hz circa.
This question of 2Pi to 4Pi space is grey zone as it seems everyone has a personal way to include this in the dev. Rare are those whom can measure low enough. As the floor is always too much near the cabinet outside (the rodes that elevate it are not high enough for the bass, one of the diy way is to put the loudspeaker on the side outside very far from near walls but the soil.
Then to measure at sweet spot and futhers areas in room to see the sum of the room behavior with the loudspeaker. You will see it is never flat anyway cause the room modes...
@glowling : can you definite what is the midrange windowss you talk about please, is it the one of the OSMC (around 400 h irrc low pass) ? Mid beginns at what 200/300 hz in charts ?
It is off topic but I think it is simply a PA upper bass/low mid woofer to be married to a compression in the 1k hz plus range as all the PA. Now the home needs are less demanding than PA in max volume. However it migth a little help perhaps according the rooms and tastes, but most of the hifi tower are lacking there anyway... many are abits with 2 6.5" to 2x 8" max per channel. Bigger bass system are not the majority (WAF, size, etc)
Troels is abstracting it from an Excel Specsheet from SanSpeak... it is a sim with perhaps the less precise tool existing... It is highly inacurate, you can just believe his measurement that are gated in room above 300 hz circa.
This question of 2Pi to 4Pi space is grey zone as it seems everyone has a personal way to include this in the dev. Rare are those whom can measure low enough. As the floor is always too much near the cabinet outside (the rodes that elevate it are not high enough for the bass, one of the diy way is to put the loudspeaker on the side outside very far from near walls but the soil.
Then to measure at sweet spot and futhers areas in room to see the sum of the room behavior with the loudspeaker. You will see it is never flat anyway cause the room modes...
@glowling : can you definite what is the midrange windowss you talk about please, is it the one of the OSMC (around 400 h irrc low pass) ? Mid beginns at what 200/300 hz in charts ?
It is off topic but I think it is simply a PA upper bass/low mid woofer to be married to a compression in the 1k hz plus range as all the PA. Now the home needs are less demanding than PA in max volume. However it migth a little help perhaps according the rooms and tastes, but most of the hifi tower are lacking there anyway... many are abits with 2 6.5" to 2x 8" max per channel. Bigger bass system are not the majority (WAF, size, etc)
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Klippel has perfected how to measure speakers and it can be done manually with other tools. But it requires some patience and detail, not something everyone has.
Someone needs to send an OSMC to Amir at https://www.audiosciencereview.com/
Many speakers measured very accurately there, great site. They have a tutorial on how to measure speakers manually.
NOTE: I was just referring to the mid range driver, the Volt VM752. Excellent mid range, very open, transparent, and clear. Yes, all those terms that are impossible to measure. To be sure, it measures well too!
Someone needs to send an OSMC to Amir at https://www.audiosciencereview.com/
Many speakers measured very accurately there, great site. They have a tutorial on how to measure speakers manually.
NOTE: I was just referring to the mid range driver, the Volt VM752. Excellent mid range, very open, transparent, and clear. Yes, all those terms that are impossible to measure. To be sure, it measures well too!
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Oh I think people here didn't wait for them and now how to measure according their own trade offs and possible access to external surfaces. For sure not everyone has a Klippel bench.