Minimus 7 Loudspeakers - Measurements
- Thread starter Zilch
- Start date
skywave-rider
Slumming in Akihabara
Yes I did, Ray.
I'm just into the leading edge of that. There's supposed to be a tutorial included with the John K guide; have not located it yet. I'll make the probes and look into buying a scale for delta mass measurements this weekend.
Pz-2.1 is up and running on 7Ws. Seems to be more open, with a better low end and less muddle on multi-instrument tracks (symphonic or chamber). The high end is there, but not in that sizzle way of the stock version. I used Madisound parts for the inductor and Rs. The parts box did the rest. I build a new x-over on scraps of thin hardwood with high end binding posts and glued/screwed into the 7Ws. The caps need to break in and then I will have a better idea of the real sound. It is definitely a refined mini-monitor now instead of the sonic muddle of the stock Min 7. I did the eBay mod too on a metal pair of 7s, and it is just a more refined sonic muddle. PZ-2.1 is on another level!
Saint Johnny
Bon Ton Roule
:thmbsp:
I wished I was knowledgeable enough to try this, as I have about 4 pairs of M7's that I always felt just weren't quite all they were cracked up to be.
Zilch, how about doing some tests, and mods on that other RS perennial under-performer, the Pro-LX5 with the Linaeum tweet?
skywave-rider
Slumming in Akihabara
I found the hardest part was getting a hand into the woofer cutout. Zilch's illustrations make it otherwise easy. It's kind of like a kit.
Go for it!
vintagelubbr
Certified Clown
CV literature
Oooops sorry folks, wrong thread....Just ignore this post........Kind new at this...
Oooops sorry folks, wrong thread....Just ignore this post........Kind new at this...
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Build the X-over as a module and install it through the woofer hole with everything already glued/soldered together. I installed the inductor last, through the tweeter orifice and pre-drilled all the holes for its mounting bolts. Instead of the wire nut to inductor/woofer/3 ohm I used a terminal lug screwed to one of the mounting bolts and soldered all three wires there. This project proves the importance of X-over design in speaker performance. Those "mundane" RS drivers can really sing if the X-over is up to snuff.
For anyone building the mod and pondering mounting options, here's a
method that's worked for me.
Found this extra undrilled boss above the terminal port inside the
cabinet. Drilled and tapped, a crossover can be secured as a complete
assembly without needing any holes through the cabinet.
(Note that this is already drilled and tapped in some early model M7s)
Mind the depth or you'll drill through at the rear product label. I
started with a taper, followed by a bottom tap.
4-40 screw works well -- especially since I had those taps.
Circuit and binding posts mounted on a rigid chunk of hardboard.
Glued those lower resisters down after snapping the pics.
Test fit. Slides in (and out) easily. Install 3 screws and yer done.
The tapped boss is slightly taller than the raised terminal area. That
works well once gasket is added.
I also laminated some cosmetic thin black plastic for the exposed rear
area.
Upgrading from stock spring-clips alone is reason enough to do the mod!
This PZ crossover mod is the real deal. Just what the world of M7
enthusiasts has been waiting for. Spent a day of quality time listening
after the upgrade. The rough edges are gone -- none of the listener fatigue so usual
after a couple of hours in stock form.
I plan to take measurements and A-B against a stock pair. But business is
taking me out of town for a couple of weeks, so it will be awhile.
A big THANK YOU to Zilch and Pete and AK for finally realizing the level
of performance these speakers were long suspected to be capable of.
method that's worked for me.
Found this extra undrilled boss above the terminal port inside the
cabinet. Drilled and tapped, a crossover can be secured as a complete
assembly without needing any holes through the cabinet.
(Note that this is already drilled and tapped in some early model M7s)
Mind the depth or you'll drill through at the rear product label. I
started with a taper, followed by a bottom tap.
4-40 screw works well -- especially since I had those taps.
Circuit and binding posts mounted on a rigid chunk of hardboard.
Glued those lower resisters down after snapping the pics.
Test fit. Slides in (and out) easily. Install 3 screws and yer done.
The tapped boss is slightly taller than the raised terminal area. That
works well once gasket is added.
I also laminated some cosmetic thin black plastic for the exposed rear
area.
Upgrading from stock spring-clips alone is reason enough to do the mod!
This PZ crossover mod is the real deal. Just what the world of M7
enthusiasts has been waiting for. Spent a day of quality time listening
after the upgrade. The rough edges are gone -- none of the listener fatigue so usual
after a couple of hours in stock form.
I plan to take measurements and A-B against a stock pair. But business is
taking me out of town for a couple of weeks, so it will be awhile.
A big THANK YOU to Zilch and Pete and AK for finally realizing the level
of performance these speakers were long suspected to be capable of.
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Nice job, Stuart, and thank you for this presentation. I have parts to do similar; mine are going in 7Ws. :thmbsp:
Should, if you series/parallel them back to the stock impendance.... :yes:
Sir.Byrd
Lunatic Member
That is the plan, man!
I am getting 15 more speakers this weekend, I just will need 15 more after that.
Sir.Byrd
Lunatic Member
Series/parallel, should be easy.
The hard part is bringing the woofer and tweeter leads out separately, unless they're all the ported version....
The plan is to build a custom cabinet for all of them (I think 16 pairs is the goal) with the summed volume of all of the smaller cabinets, and then bypassing all of the crossovers and hooking it up to a Zmod crossover.
Right now all of the crossovers are in place... when I played 8 of them yesterday it did not sound very good, not nearly as good as the 4 before. It could be that I think I must have wired some of them out of phase to reach 6 ohms, I still have a lot of wiring to figure out. I can wire only certain amounts of speakers in correct phase and impedance and that is 1 pair, 4 pairs, 16 pairs, and 64 pairs...
It works on squares. You can do it with 9. Do 3 sets of 3 and you'll come out with the same impedance as a single. With 8 you'll have to do some odd combinations which will change the crossover point.
shimniok
Super Member
Last time I read thru this thread nobody had played with the Walnut Minimus 7s ... I just took the plunge on a pair... from looking at them it appears they are real wood boxes? So, I would think the speakers would respond a little different than their metal counterparts, right?
No. Just do it.... :thmbsp:
Line arrays don't work real well unless you play by the rules, one of which is you've got to listen from 10X the stack length for them to sum coherently. I think that's the number; Ray knows.
Here's the Keele link again:
http://www.xlrtechs.com/dbkeele.com/PDF/Keele (1989-10 AES Preprint) - Bessel Arrays.pdf