Realistic Minimus 7 mod, improvement? Maybe

[saabracer23]

I’ve seen a few posts where people will replace the woofers in their Minimus 7s in hopes of them sounding better. I’ve thought about rebuilding the crossovers, but thought before hand I would replace the woofers and see how they sound. Usually I see the woofers used from companies like Dayton and such.

I have a decent stash of Audax Aerogel NOS and have several pair of the AM100Z0 midrange/midbass drivers. These should be a bit nicer than the stock driver, I’ve read that they’re giant killers. They happen to be a perfect fit and the holes line up nearly perfectly.

I haven’t had a chance to listen to them quite yet and once I do I’ll probably let them play for awhile before judging them. I think since they’re brand new I’ll need to let the drivers break in and let the suspension loosen up a little. They look nice, hopefully they sound good too. I wonder what Pete’s crossover will do with these mids?







Dan

 

[smccrary]

 

[RTally]

The original, unmodified Minimus 7 has the woofer running wide open, no filtering. The tweeter has a second order filter. The first option should be to fix the crossover before messing with the drivers. This is the definitive thread on the Ziltch mod: http://www.audiokarma.org/forums/index.php?threads/minimus-7-loudspeakers-measurements.199790/
See post #601 for schematic and parts list for PZ 2.1 and post #691 for pics of mod parts and circuit.

You may want to confirm that the replacement woofer can run wide open in conjunction with the crossover point of the tweeter. If the replacement woofer does not roll-off nicely or if its frequency response overlaps the tweeter, then the resulting sound will be less than it could be.

 

[Pete B]

Have you seen the specs, very nice flat response. You know back in the 1980s I spoke
with the Polydax office in the US and told them that someone should make a small
midrange like that. Anyway here's the spec:
http://www.audax.com/archives/am100z0.jpg

Specs look about right for the M7 off the top of my head.

 

[Pete B]

You know, when you put a nice mid in there, and if you also put something like an XT19
tweeter it makes me think of a head for something similar to a KEF 105:

 

[saabracer23]

You know, when you put a nice mid in there, and if you also put something like an XT19
tweeter it makes me think of a head for something similar to a KEF 105:
View attachment 1220845

Thanks Pete, I was hoping you were going to chime in. It’s funny you say that because the 105.1 are my main listening speakers downstairs.


Also you meantion the xt19, I happen to have a couple different xt25s. Should I try mounting the smaller pair? Be completely different speakers at that point.


Also, I happen to have several of the AM100G2 as well which has the exact same frame to it will physically fit. Does it look like it could be an even better candidate than they aerogel?

http://www.audax.com/archives/am100g2.jpg

Thanks,
Dan

 

[jdmccall]

I really like the Minimus/Optimus 7/77 speakers. I've certainly owned a bunch of them! Currently running four Optimus 7's as surrounds in A/V rig, with a pair of 77's for L and R fronts. Anyway...it's cool to see someone trick'em out a bit. See what can be done with them. Best of luck!

 

[saabracer23]

Alright, so I’ve had them going for about two hours now and thought I’d give some thoughts on them. I’m powering them with a small Rotel 50 watt X 2 integrated. I was expecting a decent change, but there was a much larger change to the sound than I thought!

First off the bass, no joke it sounds like there is a pair of ported 12s in the room now. I don’t know how they’re doing it. Seriously though, they’re Minimus 7s. Not much you can do with tiny sealed cabinets. The bass seems a little punchier and a little more prominent, but not much. As the suspension continues to soften up that may change. So it may be slightly better, but they wouldn’t mind a sub to help them out.

Now the mids, holy moly. It’s not that the mids are more forward, which they might be slightly, but they’re so incredibly clean and clear. They meet seamlessly with the tweeter which was nice to hear. If I get time later I’ll mic them and post their response compared to the originals. I started by listening to a Pandora station that played stuff like Maroon 5, Diana Krall, Johnny Cash, and the like. Vocals, especially female are so articulate, it’s crazy. I then listened to Dave Brubeck, Oscar Peterson, Chet Baker, Dizzy Gillespie, and a couple others. Instruments sound sooooooo good haha, so good! Strings, brass, woodwinds, percussion, they sound so real. This little Audax driver is really special, I’m starting to see why people like it so much.

If I get time I may still swap out the Audax AM100g2 just to see how they sound, unless Pete comments back that they don’t look like they’d be any better. I’m considering using two more pair of these Aerogels in a WMTMW design.

Anyways my thoughts.

Dan

 

[Pete B]

I think that the AM100G2 should work just as well perhaps better.
They sure look like a perfect fit.

 

[saabracer23]

I think that the AM100G2 should work just as well perhaps better.
They sure look like a perfect fit.

Well I put the AM100G2s into the cabs and I’ve been listening to them all day. I think they work better in this application overall. I lost a little bit of the detail the aerogels had, but these have a fuller sound. There is more heft to male voices and these have a little bit better bass. I think the Aerogel is a great choice for these and if I had a sub to run with these the aerogels would stay in. I like these how they are with no sub.


Dan

 

[grinner]

I already have installed the litekeys kit on numerous 7's. Would I be able to recognize any sonic benefit by implementing any of the PZ2.2 HF crossover modifications on these or should I just keep them as they are? Please bear with me, I'm a newbie. (This was also posted onthe Minimus 7 PZ-2.2 Mod DIY Circuit Board by Pete Basel forum.)

Thanks in advance for your attention to this issue and for sharing all of your knowledge and research in all of the forums.

 

[2rileylaw]

I thought I 'd try swapping out the stock "crossover" in my Minimus 7's (bought in 1980) with a pair I found on the big online mall. I'm blown away by the clarity of the mids and highs- don't sound "spiky" when turned up. The lows sound cleaner. I had to mount the new crossovers on the interior side, next to the tweeter, replaced the ancient fiber glass with some "egg crate" looking packing foam.

 

[radlid]

Hi there, sorry for the newb question but; the 40 ohm 10w resistor is out of stock at PE. Can I use the 40 ohm 20w instead? Thank you

 

[Stan man]

yes