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Old 9th August 2003, 02:16 AM   #1
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Question Does this curve look sus?

Hi All,

I just downloaded a morel catalog from madisound which had a freq plot for a Morel MW-144. which I'll attach here:

I've run a simulation in speaker workshop with two of these in a 8L enclosure, and it is starting to roll off at around 200Hz, -3db point is 88Hz. So the question is, Is this freq plot from the land of the fairies, or am I doing something very wrong!!!

Reagards,

Tony. Yeah I'm sick of typing wintermute
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Old 9th August 2003, 04:34 AM   #2
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Well, what do you expect when you put '10lbs in a 5lb sack'? You'd sing ~an octave higher too. The T/S max flat is 8.93L/49.7Hz, but putting two in <what one requires...... WRT the top end, this is mostly governed by its Le, and 0.32mH/1kHz is very low, so its HF BW seems reasonable to me. Also, its mass corner is (Fs*2)/Qes = ~196hz, hence the beginning of its HF roll off to its mass controlled ~flat portion of its BW.

GM
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Old 9th August 2003, 05:26 AM   #3
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Quote:
Originally posted by GM
Well, what do you expect when you put '10lbs in a 5lb sack'? You'd sing ~an octave higher too. The T/S max flat is 8.93L/49.7Hz, but putting two in <what one requires...... WRT the top end, this is mostly governed by its Le, and 0.32mH/1kHz is very low, so its HF BW seems reasonable to me. Also, its mass corner is (Fs*2)/Qes = ~196hz, hence the beginning of its HF roll off to its mass controlled ~flat portion of its BW.

GM
<grin>

Hmmmm. I guess I didn't consider that the response curve shown was probably taken in an optimal enclosure. The manufacturer supplied response curve I have for my Vifa 10" was tested on an infinite baffle 320L box (which I can assure you is not optimal )........ I guess it would help if it stated how the driver was tested huh!

Sorry I'm totally new to sealed enclosures only ever worked with bass reflex (and never with two drivers either).

Also what is WRT a TLA for

Tony.

edit: I guess I still a bit suspicious that a 5" driver could be pretty flat down to 50Hz too.
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Old 9th August 2003, 05:53 AM   #4
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WRT = with regard to/with reference to.

Yeah, manufacturers don't all use an IEC baffle or some other standard, so all you really have to go on are the published specs, which can be pretty far off too, further complicating making an informed choice.

I have some discontinued Radio Shack el cheapo car audio 5" fullrange speakers that are flat to 40Hz in a ML-TL. It's all about having the right electro-mechanical properties. Of course neither it nor the Morel will play very loud (especially the fullranger, with only ~1mm Xmax) due to limited Vd/displacement power handling.

GM
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Old 9th August 2003, 06:43 AM   #5
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Quote:
Originally posted by GM
WRT = with regard to/with reference to.

I have some discontinued Radio Shack el cheapo car audio 5" fullrange speakers that are flat to 40Hz in a ML-TL. It's all about having the right electro-mechanical properties. Of course neither it nor the Morel will play very loud (especially the fullranger, with only ~1mm Xmax) due to limited Vd/displacement power handling.

GM
And here was I trying to figure out what audio term it was

I must admit that years ago I was at a guys house and he had these mini speakers that were about the size of bricks (actually probably a bit smaller). Must have been 3" drivers max. The bass from them was nothing short of amazing, and he definitely didn't have a sub!

I'm looking at an MTM config so the efficiency should theoretically be quite high, the published power handling is 150W (and I have a 100W amp, so I don't think volume is going to be an issue I certainly can't turn it up full volume now without going deaf and the existing speakers are only about 88db sensitivity.

Anyway still only looking at options, but when you start to put high quality, sheilded, and high power handling in together, it starts to limit the choices (although I should go and do some more research, as before I was put on the MTM path, I was only looking at drivers with at least 89db efficiency!

I should run some sims in some other programs too, damn HD crashes, have to dig them up and reinstall.

Tony.
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Old 9th August 2003, 08:27 PM   #6
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>I'm looking at an MTM config so the efficiency should theoretically be quite high, the published power handling is 150W (and I have a 100W amp, so I don't think volume is going to be an issue

====

Hmm, based on published specs, it's ~85.73db/w/m, so adding one increases it to ~88.73dB/W/m, and due to halving the resistance, sensitivity increases to ~91.73dB/2.83V/m. Not too smashing by my standards.

Assuming you limit them to ~Xmax to keep distortion low, each driver can only handle ~45W below 90Hz, so ~109dB/45W/m is about it, so if you want peak power handling you'll need to XO to a sub at ~250Hz.

Of course if you sit close, then 45W/driver may be sufficient.

====

>I certainly can't turn it up full volume now without going deaf and the existing speakers are only about 88db sensitivity.

====

Well, what we're talking about here is compressed Vs uncompressed dynamics (the stuff of which some semblance of capturing the emotion of the sonic event resides), not how loud they can play.

Anyway, folks tend to consider a sound 'loud' based more on distortion levels than SPL per se. Folks with typical consumer speakers are always amazed at how loud they prefer to listen to mine (>103dB eff.), yet thought it wasn't as loud as when their's are 'cranked'.

====

>Anyway still only looking at options, but when you start to put high quality, sheilded, and high power handling in together, it starts to limit the choices (although I should go and do some more research, as before I was put on the MTM path, I was only looking at drivers with at least 89db efficiency!

====

Consider this as a means to increase your choices: two drivers placed magnet to magnet create a shield for both as if they each had a bucking magnet, so no need to be limited to shielded drivers. Now, instead of an MTM (with its own limitations), you have a bipole that can be configured to be a 2.5 way in a compact height/depth package. Great for computer or HT systems.

GM
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Old 10th August 2003, 03:56 AM   #7
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Quote:
Originally posted by GM

Hmm, based on published specs, it's ~85.73db/w/m, so adding one increases it to ~88.73dB/W/m, and due to halving the resistance, sensitivity increases to ~91.73dB/2.83V/m. Not too smashing by my standards.
We must be looking at different specs! According to specs from morel Israel, Sensitivity 1W/1M 88db (or have you calculated the sensitivity based on other params???)

Quote:

Assuming you limit them to ~Xmax to keep distortion low, each driver can only handle ~45W below 90Hz, so ~109dB/45W/m is about it, so if you want peak power handling you'll need to XO to a sub at ~250Hz.
Hmmm looks like I need to read up some more on power handling

Planning to xover to sub at 80Hz, although when listening to 2 channel, may increase that a bit (variable active xover).

Quote:

Well, what we're talking about here is compressed Vs uncompressed dynamics (the stuff of which some semblance of capturing the emotion of the sonic event resides), not how loud they can play.


Headroom!

Fair enough. Morel claim 1000W transient power handling for 10ms, shouldn't be a problem?

Quote:
[
Anyway, folks tend to consider a sound 'loud' based more on distortion levels than SPL per se. Folks with typical consumer speakers are always amazed at how loud they prefer to listen to mine (>103dB eff.), yet thought it wasn't as loud as when their's are 'cranked'.


Can't stand listening to loud where loud means distortion, my amps distortion figures are are < .01% THD at 100W into 8 ohms. One of the reasons I used to get asked to bring my amp and speakers to parties, wasn't because it was louder, but because when you turned up the volume it sounds good. I used to blow a lot of tweeters though (till I invested in some polyswitches), always on stuff with high dynamic range, the tweeters were cheap, and only rated at about 8W rms.

Quote:

Consider this as a means to increase your choices: two drivers placed magnet to magnet create a shield for both as if they each had a bucking magnet, so no need to be limited to shielded drivers. Now, instead of an MTM (with its own limitations), you have a bipole that can be configured to be a 2.5 way in a compact height/depth package. Great for computer or HT systems.

GM
Oh dear not another option, I'm going to go insane

Tony.
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