Minimus-7 retrofit

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A friend of mine was going to throw 2 black Minimus-7 in the trash after buying a Bose home theater on Boxing Day. :xeye:

I know these are not the greatest but they do a pretty good job for their size. Being on the lookout for my next DIY project (most probably TB's, probably ISA enclosures) I thought it wouldn't hurt to grab these Minimus before they end up at the landfill site.

After removing the front grill, I noticed that one of the tweeter is damaged. The soft dome has been crushed quite a bit. First question: In such a tweeter, is the dome actually doing the "real work" or is it just a protecting membrane ? Would "pulling" the dome back in place do any good or shoukd I simply replace the tweeter ? What would be a good replacement tweeter for this speaker ? The cabinets badly need a new paint job. What type/make of paint would you recommend ?

Last but not least, I read somewhere that there are "upgrades" for these speakers. IIRC, it mostly concerned the XO. Do they really make a difference ?

As always, thanks for all the help. :cool:
 
Minimus 7 refit

Hello Fireman

The domes are actually producing the sound. Therefore the tweeters should be replaced, if they still sound distorted after pulling them out with a needle. Always replace tweeters in pairs.

The main problem is finding a tweeter to fit the box, since the mounting plates on Minimus tweeters are rectangular, not round or square, like most tweeters. You may have to make a cardboard adapter for the hole, and you may have to cut off two sections from a tweeter that has a round mounting plate (I used a hacksaw).

Also, choose a tweeter with fairly low sensitivity to match the woofer. Neodymium magnet tweeters are now becoming affordable, and they often have sensitivities in the 85 - 89 dB/watt range.

I haven't noticed a great improvement when I upgraded the crossover, as the woofer has a built-in smooth rolloff in the high end.

I've refitted these speakers with different woofers with good results.

Black laquer paint should work.
 
Minimus 7s should be fine

I have had Minimus 7s for 23 years and they have been beat to crap for most of that time. They still sound fine with the domes crumpled. I now have them hiding in a veneered box with a pair of the Minimus-7 replacements (AV-44) in the box too. They are arranged d'appolonito style with the woofers on the top and bottom and the tweeters in the middle. The Bass reflex Av-44 makes too much port noise so I high passed it with a 220 uF cap to get rid of the lows it can't really handle anyway. This combo sounds great!!! Your friend got rid of better speakers than the ones he got for xmas...despite the price.
 
Honestly, on the paint issue, I think some black spray paint would do fine... I don't know about your models... but my Minimus 7's (which are my current computer speakers powered by a Yamaha RxV670) appear to have a metal cabinet... I would think some Rustoleum, either regular or Hammer Finish would look sweet. Perhaps the hammer finish bronze...

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DAMNIT! Now I wanna paint mine! I hate how much I love this board! :D
 
Stephen: Replacing the tweeters, that's what I had in mind. Now I need to find a source for the replacement drivers. :xeye:

Gringo: Good idea. I have another pair on loan to my in-laws. If I can get a hold of them, I think I will try your idea. ;)

HiggityHank: The hammer finish sounds great. I'm not sure about the bronze color though. I've never actually seen it. I might have to try it on something else first. :cool:
 
frugal-phile™
Joined 2001
Paid Member
Re: Minimus 7 refit

Stephen said:
The domes are actually producing the sound. Therefore the tweeters should be replaced, if they still sound distorted after pulling them out with a needle. Always replace tweeters in pairs.

I wouldn't actually use a pin to pull a dome out... if a simple "Monica Lewinsky" treatment doesn't pop them back out, you should be able to pull them out, disassemble them, push the dome out from the back, and then reassemble them.

dave
 
The hammer finish bronze is more a charcoal gray color... I don't know what they were thinking... but it's odd. Perhaps they were thinking of much older bronze... or just wanted a clever name for "Metallic Charcoal Gray"

Why can't companies name anything it's actual color anymore... it's gotta be all "Super Ultra Chameleon Flourescent Muave Pearl" instead of "Blegh..." like what everyone else will call it. ;)
 
replacing tweeters

Hello Fireman

I agree with dave (planet10). Disassemble the drivers and pull the domes out-- assuming that the domes and voice coil assemblies can be separated from the magnet assembly. Try a pin as a last resort.

The difficulty in replacing the Minimus tweeters is their oddball rectangular mounting plate. It would nice if you could adapt the plates to other tweeters. I envision removing the mounting plates of the replacement tweeters and attaching the Minimus plates with "Goop" glue. Best of luck.

Stephen
 
frugal-phile™
Joined 2001
Paid Member
Re: replacing tweeters

Stephen said:
It would nice if you could adapt the plates to other tweeters. I envision removing the mounting plates of the replacement tweeters and attaching the Minimus plates with "Goop" glue.

2 problems with the goop route -- you are never going to disassemnble them again, and it has a "thickness" that could interfere with proper seating. Better to drill new holes in the Minimus bezel to match the replacement tweeter.

I wouldn't be surprised if you could get an actual replacement from RS (you might shudder at the price thou).

Just checked -- doesn't look like i have a replacement tweeter (at least on 1st pass)... i did have a replacement midbass i used to fix the pair i have.

dave
 
AV-44 tuned to 28.5HZ!!

This discussion got me missing some of the real bass I was sure I heard from these Minimus 7 replacements(alas they too are now defunct). So I used the volume of the box and the port dimensions to work backwards to find the Fb(tuned frquency of the box/port combo) and it turned out to be about 28.7 Hz. So a larger..say 1" DIA port which might eliminate the port noise would be almost 7" long. The only way to get my bass back is to get rid of the High Pass cap I mentioned earlier and drill out the port to accomodate a 1"DIA port, remove the old tube and extend the new 1" DIA tube out 7" externally from the box...or put part in the box and part extending out from it. I must say that these two boxes(Minimus 7 and AV-44) together give a sound quality greater than the sum of their parts. The stereo image was quite poor with just one set of either speaker model running but together piled on top of each other as previously described makes the boxes disappear into a soundstage. Before it was nice sound but from a box...now it is music.
 
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