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Old 19th April 2009, 06:47 AM   #111
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Quote:
Originally posted by tresch
So what about a 3-way CHR70 floor stander, with the top and bottom drivers running mid-bass, and the center one running highs.
Should work fine. It is not a new idea, but i haven't seen anyone execute it yet.

dave
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Old 19th April 2009, 08:34 AM   #112
tresch is offline tresch  United States
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re: 3 way floor stander

Quote:
Should work fine. It is not a new idea, but i haven't seen anyone execute it yet.
I was also thinking about doing a 2.5-way setup, just using all the same speaker. 3 CHR-70s, one running tweet, one running mid AND bass, and one running only bass

The difference is very subtle, really. You have two midwoofers with a filter on both cutting the midrange down from the baffle step, or you have one driver running full volume midrange, and a second one running (essentially) none. Of course, since I'm going to be doing all first order filters for the crossovers, all the transitions will be rather gradual. In the end it's probably just a matter of which one is less complex to build. Thoughts?

I'm thinking I'm just going to have to try both
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Old 19th April 2009, 09:30 AM   #113
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Quote:
Originally posted by italynstylion
The first word or sound that comes to mind is WOW
These things are just unreal! I've only listened to them for about 10 minutes but I'm blown away... First thing I noticed from the moment I lit them up was the bass response. Ignoring the fact that it's even there in the first place, the second surprise is that it's beautiful....no other word to describe it... But since the vents on the lotus design fire forward, at the listener, it seems to work great even in a poorly set up room. The drivers don't move very much for the amount of low end they are providing.


Glad they're working. There are advantages & disadvantages to front or rear firing horns -as a personal preference, I tend to go with forward firing (as if anyone couldn't work that out ), especially for this style cabinet, which is operating over a relatively narrow BW & you don't have concerns over midrange output interering with the direct radiation from the driver.

Excursion from this box with a single driver is pretty acceptable -you wouldn't want to be cranking Motorhead at live SPLs in a barn conversion, but in a modest space listening levels, certainly decent, especially as the MA drivers have plenty of travel. By doubling up the number of drivers, you're instantly hacking driver excursion; each should be moving about 1/4 that of a single unit for a given SPL (it halves by adding a second unit, and then that is halved again by sharing it between the two drivers). More dynamic headroom & ultimate linear SPL capability is the result.

Quote:
PPS: Scott, the front baffle is 5" wide on the interior piece of wood. The driver's flange is 4.88" wide. What is left at the edges is a paper thin piece of wood. It's so close it's ridiculous.
No it's not. Yes, you have to be careful, but from what you say, you managed it, and are fairly pleased with the results?
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Old 19th April 2009, 02:10 PM   #114
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Yes Scott. very pleased with the results. I haven't even lined the interior with anything yet so I'm interested to see what effect lining some of the walls will have.

These speakers sound very live if I can use that word. The first song I turned on for my girlfriend was Jason Miraz-I'm Yours. About 5 seconds into the song she said, "It sounds like he's in the room..."

And I said, "yep..that's the point!"
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Old 19th April 2009, 02:31 PM   #115
Henkjan is offline Henkjan  Netherlands
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Quote:
Originally posted by HareBrained
.... I'm a little surprised at the amount of rise high end. I can't say that I hear that in mine.
I don't hear that either (and don't see it in other's measurements), possibly 2 reasons:
- my mic is not calibrated yet
- listning slightly off axis already solves it as well..
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Old 19th April 2009, 03:47 PM   #116
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I suspect the former -according to the published data (and the MA published specs are trustworthy, unlike most) there's a slow rise above the telephone band up to ~12KHz, the level of which is similar to the small designed in centered around 500Hz. 30 degrees off axis rolls that off nicely, & you're unlikely to need to be that far off.

Lining the interior will cut down on unwanted reflections & some higher harmonic modes in the chamber that will be interfering with the output. It will likely sound less attention-grabbing, but smoother & easier to listen to over an extended period. I design for minimal damping though, so go easy with it.
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Old 19th April 2009, 04:06 PM   #117
Henkjan is offline Henkjan  Netherlands
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OK, I more or less came to the same conclusion after looking at the datasheet

on the lining, What material do you suggest.. I usually use wool-felt for wall lining and acrylic fibre (the wool like stuff) for volume damping. I was planning on some felt behind the driver (50% of rear wall and top) and some BAF in the bottom part of the cab
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Old 19th April 2009, 04:43 PM   #118
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Design dependant really, but that sounds like it should be about right for your boxes.
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Old 19th April 2009, 08:57 PM   #119
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Quote:
Originally posted by tresch
I was also thinking about doing a 2.5-way setup, just using all the same speaker. 3 CHR-70s, one running tweet, one running mid AND bass, and one running only bass

The difference is very subtle, really. You have two midwoofers with a filter on both cutting the midrange down from the baffle step, or you have one driver running full volume midrange, and a second one running (essentially) none. Of course, since I'm going to be doing all first order filters for the crossovers, all the transitions will be rather gradual. In the end it's probably just a matter of which one is less complex to build. Thoughts?
You should be XOing 300-500 Hz. Not a lot of point going 2.5 way. With the "bass" drivers in series they will have the same sensitivity as the single mid-tweeter (if you are using a voltage amp). Could be some issues with having to deal with baffle-step. Maybe 4 CHR-70 in series/parallel XOed to a single CHR-70 mid-tweet at just below the bafflestep.

dave
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Old 21st April 2009, 04:11 AM   #120
tresch is offline tresch  United States
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There are some things I haven't tested out myself and thus I am curious about, as I haven't found really concrete info on it, yet.

In regards to serial wiring, you have two speakers each receiving half the power from the amp. Each speaker is quieter, but you have twice the moving surface area. Does this equal out? As far as acoustic volume, which is louder, one speaker with 50 watts, or two, each receiving 25? I'm sure this is a complex question that varies depending on the efficiency of the speaker, and how the efficiency changes by volume.

If I were to have a 3 speaker configuration, with one speaker as a mid-tweet, and two bass drivers crossed over right at the baffle step, I would want the bass drivers to be MORE sensitive overall than the high, to accomodate for the baffle step. If two speakers in series are essentially the same sensitivity as the mid-tweet, I would still need to attenuate the mid-tweet in order to compensate for baffle step.

On the other hand, would it be reasonable to wire the bass drivers in parallel to increase output, and then attenuate the bass drivers to match the mid-tweet? This would result in an overall impedance between 6-8 ohms*, depending on how much resistance needs to be added to the bass network, which would be more friendly to your basic Home Theater amplifier, which is going to be driving these speakers.

*two 4ohm bass drivers in parallel = 2 ohms + some amount of arbitrary resistance, wired series with a 4ohm mid-tweet = 6 or more ohms

I'm just thinking out loud, feel free to ignore me or humor me with criticism! I really need to get a hold of the Loudspeaker Design Cookbook one of these days...
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