Morel MW144 deceitful specs

[wintermute]

no worries madmike

here is the link to the MW144 datasheet http://www.eltimaudio.com/products/MW 144 datasheet.pdf

I'd never really noticed that it had the impedance peak at about 75-80Hz!!! must be an in box impedance plot too.


and for other morel driver specs http://www.eltimaudio.com/products/drivers.htm

It's always puzzled me that morel Isreal doesn't have these sort of specs on its website....

Tony.

 

[Zaph]

I don't think it can possibly be the same driver, either that or something was horribly wrong with the sample he had or something went horribly wrong with his testing (no offence zaph... I know I have had some doozies at times )..... It's not just the FS that is so far out, look at the Vas less than half (closer to 1/3rd) my measurement, the le (more than three times my measurement) and the qes which is at least half as much again..... about the only parameter that bears any resemblance is the re....

My drivers are from Isreal btw....

The ones I tested were also the Isreal Morels. (which, in my opinion are the REAL Morels)

There's always the chance I screwed up the measurement, no denying that, but it's more likely that there was simply something far out of spec with the woofer. It's not like I tested a a large batch, just a pair. I've tested a lot of woofers, and I've come across some that are even further off that that, but I've come across some that are dead accurate to the manufacturers specs.

I use delta compliance because it's much more accurate than delta mass. I frequently compare modeled response with measured specs to actual measured specs in the modeled box size. Usually the F3 is right where my software predicts it to be.

I've enabled the email feature....

Does that send an email to you or is there some kind of messaging system that pops up in the forum software? I'd turn it on too if the messages stayed within the BBS software.

John

 

[wintermute]

hi John,

The ones I tested were also the Isreal Morels. (which, in my opinion are the REAL Morels)

There's always the chance I screwed up the measurement, no denying that, but it's more likely that there was simply something far out of spec with the woofer. It's not like I tested a a large batch, just a pair. I've tested a lot of woofers, and I've come across some that are even further off that that, but I've come across some that are dead accurate to the manufacturers specs.

even worse I recon that the MW144 that you had you would be more than in your rights to send back!! I would!!! could have been a manufacturing defect, maybe they were damaged in transit, dropped severly perhaps. I tend to agree that it is very unlikely that the measurements were at fault, more likely something restricting the cone movement I would guess, since it is unlikely that the cones themselves would have been lighter than normal. Various things I did to make sure I didn't have compromised results, had very little effect on the measurements (eg different clamping, even simply sitting the woofer on it's back on the floor)...the single thing that made the most difference was the drive voltage.... I set mine very low (as per dickasons recomendation) I can't remember what it is (have the levels set in quick mix) but I'd say it is below 1/2 volt.

I use delta compliance because it's much more accurate than delta mass. I frequently compare modeled response with measured specs to actual measured specs in the modeled box size. Usually the F3 is right where my software predicts it to be.

I used delta mass because I didn't have a test box (or the facilities to build it, I drive 7 hours to my parents place to get acces to woodworking facilities).... probably something I should do when I go up to do the final boxes as I'll have spare MDF. The other reason is that I bought an extremely expensive pair of scales for acurately measuring the added mass, so I feel I have to get back my investment

when I got some valid acoustic measurements, they matched up pretty well with my sim too, except that the level was rising a bit instead of falling from 200Hz down, but the F3 was pretty much spot on.

Does that send an email to you or is there some kind of messaging system that pops up in the forum software? I'd turn it on too if the messages stayed within the BBS software.

John

the person sending it gets a form to fill in which sends the email, they don't get to see your email address unless you reply.... the email you receive says it was from (for example) zaph at diyaudio, and has the senders real email address.

Tony.

PS. I've only tested 6 woofers but I think I've got it sussed now

 

[wintermute]

hi mr PushPull,

just wondering how you have gone??? I noticed the other day they morel Isreal now have the Fs listed at 52Hz on their web site for the MW144, which is pretty much what I measured.....

I'm still doubting my gated measurements.... but subjective testing with a basic 1st order crossover (ie no impedanace comp, just values chosen based on impedance at xover freq) have been very promising....

Tony.

 

[mr_push_pull]

Hi Tony, nice to hear from you

So Morel Israel updated the spec for MW144? I can swear that I saw 45 Hz the last time I checked.
Well, nothing new for me as I'm still in Israel and have no tools at hand, but in less than three weeks I'll be heading home and start working. In the short vacation I've had I had the chance to measure the drivers, and if I can remember correctly, Fs was around 85 Hz with no break-in, and after 24 hours of break in 73 Hz. Still pretty far from your results. Maybe I should try one month of break-in? Can't remember the other parameters. Meanwhile I ordered a Behringer ECM8000 microphone and hopefully I'll measure the SPL response too. I'll have some studying to do as I have no idea what a "gated response" is, haven't ever measured the SPL response of a driver before.


Calin

 

[wintermute]

Hi Calin,

bizzare!! Since you are in Isreal, maybe you should pay a visit to Morel and ask them about it!

dropping 12Hz after 24 hours is pretty significant, I'm wondering if there is something peculiar about the spiders that requires a long break in. My Units were old stock, dated 1997 and 1998... maybe they changed something in the manufacturing process.

Mine didn't change at all after my admittedly pretty tame break in (a few hours of 20Hz, a few hours at suposed resonant freq, and a few hours of white noise).

Tony.

 

[mr_push_pull]

As a matter of fact the drivers have been bought dirrectly from the Morel factory in Nes Ziyyona (or whatever that should be spelled like in English). They insisted that they'd rather not send by post (my temporary residence is in Haifa, around 120 km away from NZ), and I payed them a visit. When I found out about the huge parameter deviations I thought about calling them but never took the time to do it. Maybe I'll drop them an e-mail once. If all people were as lazy as me, that would explain why they didn't update that spec until recently

As for Fs drift with break in, after all that's only some 15%, don't judge that as absolute value, but relative. My Visaton WS170 bassmids dropped from 42 Hz to 36-37 after break-in, so that didn't strike me as strange.

I think my units are newer production (I have to check after I get home as they're not with me anymore).

 

[wintermute]

I'd definitely ask the question can't hurt! They might have had a production fault and are not aware of it

do it before you leave I'm a bit like you, I've not said anything when I should have in the past, too many times...

Tony.

 

[mr_push_pull]

I still have 19 days to do it

 

[mr_push_pull]

I've just had a look at the Morel Isarel website. It's practically a different one now. And for some trivia, the guy in the "about" square in the top left is the one that keeps the presentation room at the back of the factory, and actually sold the drivers to me. Doesn't he look like John Malchovich?

 

[mr_push_pull]

Talking about deceitful specs....

Tony, you might want to take a look at the Morel website, especially at the MW144 datasheet. It's a whole different one. Everything has been updated, graphs, parameter tables. Fs has reached 52 Hz, SPL response looks totally different, a graph for impulse response has appeared. Just compare it to the old spec spec sheet and it will look like a totally different driver, in a bad way.

Maybe someone should drop them an email, asking which specs should be taken for granted? Old or new ones?

 

[wintermute]

Hi Calin,

I'd say the new specs are the ones you should trust. Note that I did a free air measurement a while ago (don't know where I saved it, or if I did at all) I had a big dip at 1Khz not quite as wide as on the new datasheet but overall the response graph looked quite similar to that. Funny thing is, in a box there is no dip at 1Khz at all. Maybe they have decided to put the specs up warts and all

I simulated a 4th order LR crossover using my audigy II ZS and played some music. Must say that appart from the lack of low end they sounded very nice seemed about best crossing at 2.8Khz to my DMS37.

I never managed to find any datasheet on the morel isreal site, I'm glad they have them up now! the one I had was off Eltim Audio's site...... this new one looks much more realistic to me!!! (or at least it seems to match my driver much better

You might want to check this post ---> http://www.diyaudio.com/forums/showthread.php?postid=734505#post734505 the blue trace is pretty smooth IMO, yeah it is a nearfield measurement but the problem with nearfield and higher freq's is that the higher the freq the lower the relative level, I think it actually still gives an accurate idea of the smoothness, just that the magnitude is more and more inaccurate with increasing frequency.... overall I think it is pretty good after re visiting some of the measurements in dickasons cookbook, I decided that they were not as bad as I was thinking!!

Tony.