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Minimus 7 woofer tweak

G

gotvinyl

Active Member
Hopefully nobody is too tired of Minimus 7 projects for this question. I bought some 7 w's as well as the kit on the auction site that upgrades the woofer and the crossover. Only then did I read the definitive thread in this forum on the Minimus 7 crossover mod. Well, I got the kit and speakers, did the upgrade, had a blast doing it, and want to go for it again with the PZ 2.1 crossover this time.

I know the AK thread concluded that the minimus 7 drivers are adequate, but I was wondering if anyone has tried the PZ 2.1 with a beefier woofer like the one in the kit I bought: http://www.mcmelectronics.com/product/55-1856&cid=prodCrossSell.

I have uploaded the data sheet. I am a novice, so please forgive my ignorance if this is a question that takes extensive testing. I already appreciate how much work has been done on the PZ 2.1 thread already. This would be a further upgrade or alternative for people with blown woofers.

I was hoping that by looking at the attached specs one might be able to come up with the tweak for the crossover that would make this woofer work in the PZ 2.1 crossover configuration. I am happy to be the first to try it and post my results (though I don't have any testing equipment). I already have another pair of 7w's and am ready to order parts. Thanks - especially to the Minimus 7 pioneers.
 

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Alternative

An alternative: http://www.mcmelectronics.com/produ...commendation&utm_source=prod&utm_term=55-3853.

I found a recommendation by Pete B of another MCM woofer (#55-1853) in a post, and he said it is close to the stock Minimus woofer. But measuring mine with the woofer in it, it would be a very tight fit at 2.8" deep. Then, I saw Pete's reference to Zaph, and Zaph recommends the #55-3853 and says it is similar to the one Pete found, but with a cast frame upgrade. It is still pretty deep (2.5" vs. 2.8"), so I think it will be tight and might require moving th crossover around. Perhaps this is closer to the stock minimus woofer than the one in the kit I bought. Here is what Zaph says: http://www.zaphaudio.com/smalltest/.
 

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That looks like a pretty good woofer replacement. Is it drop-in with mounting holes that line up? Did you modify the Zilch x-over for the Madisound woofers?

Thanks for the feedback.
 
No mods on cRossover, other than moving things so that woofer will fit. Screw holes do not line up and one needs to dremel out the woofer hole as well...
 
mikeybc said:
I think this woofer may work quite well with its small magnet structure, I don't really care for the others with those massive magnets taking up all that very valuable airspace in the cabinet...there's not enough volume to waste.
Click to expand...
It's funny in a way, when dealing with larger cabs this is not something that would necessarily be brought up but is a damn fine point here. Good catch.
 
I wish you could hear my HT system with five minimus 7s and JBL subwoofer. It amazes me and everyone that hears it. I used the eBay crossovers. The receiver is a Yamaha that puts out 100 watts X 5.
 
DKirk, is the sub the JBL control? I am interested in matching a sub. I believe it needs a crossover point around 125 Hz. Is that your experience?
 
Build Pics

Ok, so here are some build pics of the ones with Jantzen caps/new woofers. (Keep in mind the main reason we swapped woofers is that the original woofers sounded (and measured off)-- they were also different builds-- one had paint on the frame, one didn't.)

Since I have another pair that is exactly the same zilch x-over (except Dayton caps) and with the original woofers, same binding posts...My plans are to compare these two builds A/B using a Marantz 2230...Speaker A, then B.. Blind test (I suppose I could put the grills on).

I'll let you know how it goes and what people prefer. I like the sound of these very much but plans are in the works to add a sub. I mainly use these near field and these may be paired with an Advent 300 in an office setup.
 

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I've been told that the bass should tighten-up slightly and get a tiny bit lower as they break in. Final result will likely be a Qtc of .85 and f3 of 100hz. They are breaking in nicely so far. Voices, guitar and imaging are all very nice.
 
Good work, Atwood. I am glad you posted those pics. That will help me. I have the same plastic piece to mount the x-over. I was thinking about substituting 1/8" hardboard. If I use the MCM woofer, I may need to mount the x-over parts closer to the tweeter and allow for the 2.8" depth.

Are Jantzen caps an upgrade?

Do you know how the Peerless woofers compare to MCM? I haven't picked my woofer yet and am curious how you decided.
 
Yeah, replacing wouldn't be a bad idea. Here is a pic of that plastic piece with the post area filled in with J-B Weld. Works fine...

I can't comment on the other woofer. Obviously you are limited on size. We also considered a Tymphany woofer but I don't know the model. The Peerless was more efficient though. We were mainly trying to match to the PZ 2.1 x-over....Shane said, "The Re is nearly an exact match as is the Le so the Zoble network and 1st order filter will work fine. It doesn’t hurt that the frequency response is so smooth too."

The grills even fit, although I don't use them...
 

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As far as caps... I think they are both good. Hard to say when you change two things at the same time. :-)

These are my first experience with Jantzen. But it all sounds good so far. Most of my other speakers have Sonicaps which I like a lot.

I'm sure there are experts here who can speak to caps...
 
gotvinyl said:
DKirk, is the sub the JBL control? I am interested in matching a sub. I believe it needs a crossover point around 125 Hz. Is that your experience?
Click to expand...

It's an older 10" 100 watt rms model. I believe I settled on a 120 HZ crossover point.
 
I heard these after building with a sub and they sounded fantastic, here is what Shane said "100Hz to 120Hz. Since the Minimus are 3db down at about
100Hz with a 12db per octave roll-off, the range I would work with is 80 to
120Hz then spend some time playing with phase, level and crossover point."
 
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