Minimus 7 Loudspeakers - Measurements

[Scorchin34]

I love Minimus 7s, unfortunately my pair need a tweeter and bass driver. I can buy a pair of Walnut cased versions but I prefer my metal boxed instead. I'm always looking out for spare drivers for them at yardsales and so forth, some day I'll find them. What frustrates me is that every ad I put out there looking to buy some I gett offers to buy whole sets of them. Always the way I guess.

Thanks for the great post, learn something there. :thmbsp:
Peace,
Preston

 

[Zilch]

Zilch,
are you going to offer a new crossover schematic that will improve the M7s similar to the one you can buy?

I'm just investigating presently, but it usually goes that way, yes.

I expect, at some point, there will be collaborators here....

Do you have the answer(s) to my question @ #28?

 

[Sir.Byrd]

80 hz for the sub mating, but that's just me lookin' at it.

It may be easy to pick out the subwoofer at that frequency, but to get that bass...


Hmm..

Why not make a woofer box to place under each Minimus 7 and wire a crossover in it which is a low pass and passes everything else to the M7?

 

[vinyldavid]

80 hz for the sub mating, but that's just me lookin' at it.

It may be easy to pick out the subwoofer at that frequency, but to get that bass...


Hmm..

Why not make a woofer box to place under each Minimus 7 and wire a crossover in it which is a low pass and passes everything else to the M7?

What about a sub plate amp on each of them and tune the filter for 80hz, and then run 2 mono subs...

 

[Sir.Byrd]

What about a sub plate amp on each of them and tune the filter for 80hz, and then run 2 mono subs...

No, no amp.

 

[vinyldavid]

No, no amp.

why not a powered sub?

 

[Zilch]

Y'all'll get another chance, 'cause I'm posting new nearfield bass measurements next. -3 dB at what frequency...? :scratch2:

 

[Zilch]

Impedance:

Compare to Planet10 findings:

http://www.planet10-hifi.com/minimus7/

Grille/None:

Sinusoidal Nearfield:

Comments:

1) Impedance? So it is, apparently.

2) Generally speaking, the grille enhances response slightly @ 5 kHz and attenuates it above 15 kHz.

3) Bass response, I measured #3 twice to confirm. It's apparent in the impedance curve, as well that Fc is lower. If I were the designer, I'd be all over that one to figure out why.... :yes:

 

[vinyldavid]

So Zilch, what does this mean in terms of subs? Do we cross at 100hz?

Whoa! Those have no bass it should seem....

I really wish that you could measure my -12's....they sound like they have decent bass...

 

[Zilch]

So Zilch, what does this mean in terms of subs? Do we cross at 100hz?

See if you can coax RayW back over here to take a look. :thmbsp:

Whoa! Those have no bass it should seem....

Let's pretend.

I really wish that you could measure my -12's....they sound like they have decent bass...

YOU measure them. Paratima shows how in my KLH-17 thread, nearfield, using the $50 R/S SPL meter, which every audio enthusiast should have, anyway, and test tones.... :yes:

http://audiokarma.org/forums/showthread.php?p=2290649#post2290649

 

[vinyldavid]

YOU measure them. Paratima shows how in my KLH-17 thread, nearfield, using the $50 R/S SPL meter, which everyone should have, and test tones.... :yes:

OK....once I get a spare $50...I'll give them a low freq test. :yes: I'm interested in how low they go....actually, a friend of mine has a sine wave generator....I'll probably borrow that.

 

[Zilch]

OK....once I get a spare $50...I'll give them a low freq test. :yes: I'm interested in how low they go....actually, a friend of mine has a sine wave generator....I'll probably borrow that.

Fill in the chart, courtesy member Urizen:

http://i88.photobucket.com/albums/k199/Urizen_2006/testtonechart.jpg

 

[RayW]

So Zilch, what does this mean in terms of subs? Do we cross at 100hz?

See if you can coax RayW back over here to take a look. :thmbsp:

Sheesh. What'd I do to you?

Crossing at 100Hz looks like a good place to start but it will really depend on your room. Zilch measured response near field which (pretty much) eliminates the room from the equation. It also gives you a halfspace measurement (as if the driver was mounted in an infinite baffle) which will overstate the low end if you the speaker is actually used in freespace. In that frequency range the room will play a big role as will boundaries. The distance between your sats and sub can also come into play there. I would start at 100 and season to taste based on your room and personal preference.

However, I also feel that you should measure things to get them as flat as possible and then adjust from there so you have a known baseline. Adjusting from an unknown place trying to find an unknown destination is just fumbling in the dark.

Ray

 

[Zilch]

Shades of Presidian:

 

[Fred Sanford]

Hmm..

Why not make a woofer box to place under each Minimus 7 and wire a crossover in it which is a low pass and passes everything else to the M7?

That's what I did for many years with my Canton Plus S's (like M7, but more betterer), only at ~100Hz. Rear-ported CV cabs with DVC 12" drivers. Nice.

je

 

[RayW]

Z, is that with or without crossover filter for each driver?

 

[Zilch]

Hi, Ray.

That's with the stock filter still in place, second order highpass, nothing on the woof.

I'll investigate the tweeter next. :yes:

[There's considerable improvement to be made here, folks.... :thmbsp: ]

 

[RayW]

Hi, Ray.

That's with the stock filter still in place, second order highpass, nothing on the woof.

I'll investigate the tweeter next. :yes:

Groovy. Get us that "nekkid" curve on the tweeter and we'll be set to fix 'er up.

[There's considerable improvement to be made here, folks.... :thmbsp: ]

And not to difficult either, at least the first tier.

Ray

 

[Zilch]

Le Tweet:

Don't know why it lost a couple dB; ESR of the 39 uF I put in series for protection, perhaps. Data files below for those with crossover design software.

I was able to desolder from the terminal successfully. Looks like a small working space, but it's plenty.

Also, if anyone has a dead Minimus 7 tweeter they're willing to donate to "Research," I need a plastic frame of the type shown here (just the frame,) to try some substitution options:

PM me for mailing address, please.... :yes:

 

[RayW]

Don't suppose you've got basic T/S? Re? Le? Impedance curve?