Realistic Minimus-7 Measurements

[sam_adams]

Has anyone compared Minimus 7 measurements between the metal grill off and it on? I wonder if there is any significant difference.

Measurements of Minimus 77 with the screens—both early and late model screens—on and off.

Woofer (Early and later model screen.):

Tweeter (late model screen only):

Most of the differences would not be noticeable in program material.

Comparison of the screens on early Japanese manufactured (on the left) and later Malaysian/Korean (on the right) manufactured Minimus 77. The Minimus 7 screens all look more like the the later M/K Minimus 77 screens on the right.

 

[EVDavis]

I got a pair of Solo 103 speakers but the original Foster drivers were both blown. I paid $5.00 for the speakers. Anyway, I bought a pair of Realistic 40-1197 drivers from ebay and put them in the cabinets. I placed them in an eight hole Kallax shelf, laying on its side. They are on the upper opposite end shelves, sitting on some books to bring them up higher and with LP's filling up the rest of the cubical space. These babies sound great, with excellent bass too. People need to say more about placing small vintage acoustic suspension speakers in their proper location "a bookshelf!" not stands!

 

[mhardy6647]

I got a pair of Solo 103 speakers but the original Foster drivers were both blown. I paid $5.00 for the speakers. Anyway, I bought a pair of Realistic 40-1197 drivers from ebay and put them in the cabinets. I placed them in an eight hole Kallax shelf, laying on its side. They are on the upper opposite end shelves, sitting on some books to bring them up higher and with LP's filling up the rest of the cubical space. These babies sound great, with excellent bass too. People need to say more about placing small vintage acoustic suspension speakers in their proper location "a bookshelf!" not stands!

from 1965.

heh-heh-heh.


Pair of those (Solo103 -- which don't have any BSC, unlike the Electronics Illustrated project*) in the basement -- with the original Foster (Fostex) FE-103 drivers of their era (ceramic, not AlNiCo magnets).

Fostex still makes some FE-103 variants and they're still surprisingly pleasant to listen to.
Pair of those on our (seldom used) TV in the "den".



_____________
* couple of those here, too.

N.B. No fiberglass stuffing was consumed during the CAT scan pictured above.

 

[EVDavis]

View attachment 538059
from 1965.

heh-heh-heh.


Pair of those (Solo103 -- which don't have any BSC, unlike the Electronics Illustrated project*) in the basement -- with the original Foster (Fostex) FE-103 drivers of their era (ceramic, not AlNiCo magnets).

Fostex still makes some FE-103 variants and they're still surprisingly pleasant to listen to.
Pair of those on our (seldom used) TV in the "den".



_____________
* couple of those here, too.

View attachment 538060
N.B. No fiberglass stuffing was consumed during the CAT scan pictured above.

View attachment 538061

I was messing with my JBL 44 Lancers one day and had the driver out of the cabinet and it wasn't 5 seconds I turned around and my cat Pillow was inside looking out.

 

[mhardy6647]

Oh. After writing all of the drivel above I realized that I should have added an on-topic comment about the Minimus 7 and its kin.
I wanted a small pair of loudspeakers to put atop the cabinet that contains our TV (such as it is). Tried the Minimus 7 pair (utterly stock) that I have here and was thoroughly disappointed.
Tried a few other small speakers, 'til I finally thought about trying those little Fostex "Kanspea" speakers. Much better sounding overall than the Minimus 7.
I've just never cared much for the latter.


EDIT:
PS I don't remember if I tried the SOLO103s or not.

 

[Ralph_Cramden]

I would be inclined to do the Ziltch PZ2.2 mod and then use active EQ.

Or a cheap 2-channel class D amp board with this tiny DSP project. Cheap bi-amp’d mini monitors.

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[EVDavis]

Oh. After writing all of the drivel above I realized that I should have added an on-topic comment about the Minimus 7 and its kin.
I wanted a small pair of loudspeakers to put atop the cabinet that contains our TV (such as it is). Tried the Minimus 7 pair (utterly stock) that I have here and was thoroughly disappointed.
Tried a few other small speakers, 'til I finally thought about trying those little Fostex "Kanspea" speakers. Much better sounding overall than the Minimus 7.
I've just never cared much for the latter.


EDIT:
PS I don't remember if I tried the SOLO103s or not.

In my opinion Minimus 7 speakers only sound good with the loudness on and still a slight increase in the bass. Then they come alive. Just using them flat with an amplifier isn't all that great.

 

[Mikeiver]

In my opinion Minimus 7 speakers only sound good with the loudness on and still a slight increase in the bass. Then they come alive. Just using them flat with an amplifier isn't all that great.

Still have a pair of the optimus pro 7 speakers I bought new back in the early 90s. The got used every day back then in the car being fed with a portable CD player and a Proton 22Wpc car amp. I was happy with the sound back then, not so much now that I have the money and experience to know better. I know this sounds like a dis of them and it is, at least in their stock form. Then I read that a guy named Zilch worked up a proper crossover for the minimus 7 and that the results were pretty fantastic. Now to digress a bit here. The minimus and optimus speakers, both the 7 and the 77 have what appears to be the same tweeters and crossovers. There are a couple of minor differences between the 7's and the 77's. The 7's crossover uses a 4.7uF cap and the 77's use a 3.9uF cap. Another variant I happened upon was the fact that some likely early production variants of the 77's had a proper crossover board and an additional .8uH inductor for the woofer. This small add makes a huge difference in the sound that they output compared to later variants were they got cheap and eliminated both the PCB and the woofer inductor. (I have both) The boxes vary as do the woofers between the 7 (4") and the slightly larger 77 (5") but otherwise all the same. The woofers were left to run full range while the tweeters got a 12dB crossover consisting of a 4.7uF electrolytic cap and a .4mH air core inductor. The minimus had no ports while the optimus had a port that contributed little more than chuffing to the game. Clearly they were going for maximum profits, not sound quality. The results were very muddy midrange and middling highs. Loudness on helped them alot. Back to Zilch. He worked up a proper crossover for his set of minimus 7 speakers. The design I personally have installed on the two sets of optimus pro 7 speakers I have was the 2.1 variant. Based on the parts called out he clearly used parts-express for the source the parts as I did. I bought the cheap film caps, wire wound resistors, and iron core inductor since caps, inductors, and resistors costing 10's of times more sound no different. That and these are just Fing radio shack speakers for Pete's sake! After installing the Zilch 2.1 crossover to one of the pair and listening, I was simply awe struck. The clarity and imaging of the pair was a revelation. Are they comparable to any of my Mission, Klipsch, or JBL pro monitors? No note really. But in near field or in a smallish room they truly shine.

I am working on a pair of the early 77's with new woofer and tweeters, so far the results have been very satisfying. But that is likely better off in another thread.

 

[Mikeiver]

So EJ3, and maybe others, wanted some followup on what I suspect are the Optimus Pro 77 speakers and the mods I have chosen to try so I will detail them a little bit more.
The pair of 77's I have modified started off with a pair of woofers in need of a new surround. Lacking the desire to undertake the task I decided to see if there were in fact a driver out there that might be a simple replacement. I can say that there are not to the best of my knowledge, but. There is a driver that the TS parameters indicated a good match to the volume of the 77 when the port was plugged. That is to say around .12cf. Turns out that the FatalPro 5FE120 (about $59.00 each at PE) is a "near" perfect fit other than the screw hole circle being just a smidge smaller than that of the stock driver. I carefully removed the raised rim of the frame and extended the holes another 2-3mm to allow for the stock screw holes to be used to secure the new woofer. The stock woofer has a rating of I think 40W but not sure if that is RMS or Peak. The 5FE120 is rated at 80W RMS and 160W peak and has an extended frequency range. It was a fantastic choice as a replacement but... Now the tweeters were rather lackluster and so I decided to have a look at a possible replacement for them. The form factor of the stock tweeter doesn't appear to be made by any driver supplier now so an adapter plate would likely, you should just read that as it being a must, be needed depending on the choice of tweeter. I started looking at various tweeters, their specs, their size, their dispersion, their frequency response and their power handling capabilities. After a couple of days of off and on searching at PE and Madisound I settled on one by Wavecor, the TW030WA14. This is a larger tweeter with a 30mm diameter and an extended frequency range. It also has a back chamber and heatsink making it a good choice. The bad part is that they are $115.00 each right now but I got mine on sale for $80.00 each. They do not fit the 77 as that are a round unit and the stock is a rectangle. I did up a drawing and had one of the machinist at work knock up a couple pairs of adapter plates for me out of approximately 2.5mm Al for me. The plate allows for the mounting of the tweeter. The screws mounting the tweeter to the place have to be 1/4" long to get through the tweeter and the adapter plate but remain flush. All done other than swapping out the old 3.9uF electrolytic cap for a new film. Now the pair of 77's I have, as I mentioned in the previous post, have an actual PCB with a .8uH ferrite core inductor for a 6dB low pass for the woofer and a .4uH air core inductor and a 3.9uF cap for a 12dB high pass for the tweeter. The results are pretty darn good. The mids and highs are great and the base is even pretty good for the small driver. I think that the tweeter may need a bit of a pad and I suspect that a 12dB low pass would better serve the bottom and lower mid range. I will be sweeping them soon to get some idea of the next direction I need to be going. Well that's about it for now.

.

 

[NotInYourHead]

I hope someone would measure the larger Minimus 11. It has a kind of waveguide for the paper tweeter and overall reminds me of the 1970s Technics SB-F2 which perform well in the mids and highs.

 

[Mikeiver]

So working on the damaged pair I acquired first. I have a second set of new woofers and tweeters for the second pair. I have removed the back plate from the speaker frame and then the port from the back plate. Took a fair bit of heat and time to soften the adhesive enough to facilitate breaking the bond. I then removed the residue from both. I have given allot of thought to enclosure dampening. The enclosure is ringy and bright. I have bought some EPDM double sided adhesive seam tape, aluminum foil tape, rubber flashing tape, and .125" foam sealing tape. The plan being to construct a multi layer deadening material stack and stick it to the entire interior of all surfaces. I will also be making a plate to cover the input terminal hole with a pair of banana terminals for each driver so I can move the cross over to the exterior for easy modification. This also allows for the option to Bi-Amp and use DSP to feed and adjust the pair. Will see how they compare to the other pair with a passive 6dB/12Db stock crossover in otherwise stock un-dampened cabinet with the ports plugged. Photos to follow as time allows and once I get the material stack put together and then applied to the internals.

 

[EJ3]

So working on the damaged pair I acquired first. I have a second set of new woofers and tweeters for the second pair. I have removed the back plate from the speaker frame and then the port from the back plate. Took a fair bit of heat and time to soften the adhesive enough to facilitate breaking the bond. I then removed the residue from both. I have given allot of thought to enclosure dampening. The enclosure is ringy and bright. I have bought some EPDM double sided adhesive seam tape, aluminum foil tape, rubber flashing tape, and .125" foam sealing tape. The plan being to construct a multi layer deadening material stack and stick it to the entire interior of all surfaces. I will also be making a plate to cover the input terminal hole with a pair of banana terminals for each driver so I can move the cross over to the exterior for easy modification. This also allows for the option to Bi-Amp and use DSP to feed and adjust the pair. Will see how they compare to the other pair with a passive 6dB/12Db stock crossover in otherwise stock un-dampened cabinet with the ports plugged. Photos to follow as time allows and once I get the material stack put together and then applied to the internals.

I have the wood box Minimus 7's.
I do not have a way to measure anything audio at this point.
Ringing was an issue that I noticed with the metal ones when they were available from Radio Shack.
I may or may not have some of them laying around somewhere in my stuff (most likely not, as most of my gear is in use in one system or another).
I had always thought that something like Line-X might help the ringing in the (aluminum?) ones.
It will likely be after February until I can get some useful audio measuring gear as I currently have too many projects on going and have zero audio measuring gear (well, one thing: a DB meter).

 

[barbagris]

Just wired up a pair of the Aluminium Minimus-7's in my garage. Not really what you'd classify as a pristine listening area.

I've had them since the mid '80's - I bought them as robust rear speakers for use in a Volvo 245 Estate car. They've since sat in boxes that have crossed more country borders than is reasonable without ever being unpacked.

Still work just fine (within reason) - and tbh I really can't see the point in messing about with them for now.
I hooked them up to a small stack of some Fosi Audio stuff I got on offer.

 

[Mikeiver]

Just wired up a pair of the Aluminium Minimus-7's in my garage. Not really what you'd classify as a pristine listening area.

I've had them since the mid '80's - I bought them as robust rear speakers for use in a Volvo 245 Estate car. They've since sat in boxes that have crossed more country borders than is reasonable without ever being unpacked.

Still work just fine (within reason) - and tbh I really can't see the point in messing about with them for now.
I hooked them up to a small stack of some Fosi Audio stuff I got on offer.

One can not appreciate just how scrappy the stock speakers sound until you install a Zilch 2.1 crossover and have a new listen. The difference is very telling. But not everyone has the skills to upgrade what are a pair of dirt common diamond in the rough garbage speakers. I have a couple pairs that I have Zilched and they are great for general listening. If you are happy with them then no need.

 

[EJ3]

One can not appreciate just how scrappy the stock speakers sound until you install a Zilch 2.1 crossover and have a new listen. The difference is very telling. But not everyone has the skills to upgrade what are a pair of dirt common diamond in the rough garbage speakers. I have a couple pairs that I have Zilched and they are great for general listening. If you are happy with them then no need.

I guess that the same Zilch 2.1 crossover's would help the wooded one's.
Any one do that? or have thoughts on that?

 

[Mikeiver]

I guess that the same Zilch 2.1 crossover's would help the wooded one's.
Any one do that? or have thoughts on that?

If memory serves, I think he was using one of the minimus 7 in wood. Frankly all of them, minimus/optimus 7 speakers used the same drivers and crossovers so it works on any of them. The parts are cheap and the results are great if done properly. I have the optimus 7 pro speakers which added a worthless port that I plug. Otherwise the name is just marketing the same cheap speakers.

 

[barbagris]

One can not appreciate just how scrappy the stock speakers sound until you install a Zilch 2.1 crossover and have a new listen. The difference is very telling. But not everyone has the skills to upgrade what are a pair of dirt common diamond in the rough garbage speakers. I have a couple pairs that I have Zilched and they are great for general listening. If you are happy with them then no need.

Therein lies the issue. I am fairly capable of most things technical - but soldering and I were NOT meant to be associated.

I know they're not great, but honestly I'd rather go out and buy a pair of new "somethings" rather than ruin these entirely.

 

[EJ3]

Therein lies the issue. I am fairly capable of most things technical - but soldering and I were NOT meant to be associated.

I know they're not great, but honestly I'd rather go out and buy a pair of new "somethings" rather than ruin these entirely.

I wish that more people that are not particularly good at something would admit to themselves (usually they have been trying to do it for 15 years or more) that that particular thing is just not their cup of tea. And quit trying to do it!
While I believe in "try, try again", I also believe in admitting to yourself that: hey, I just am not good at this particular thing and it's time to quit trying and let someone else handle it.

 

[Petrushka]

I wish that more people that are not particularly good at something would admit to themselves (usually they have been trying to do it for 15 years or more) that that particular thing is just not their cup of tea. And quit trying to do it!
While I believe in "try, try again", I also believe in admitting to yourself that: hey, I just am not good at this particular thing and it's time to quit trying and let someone else handle it.

In Army signal school I spent something like two weeks, eight hours a day, practicing soldering.

That’s a slight exaggeration, except for the two weeks.

 

[Flaesh]

soldering

soldering

Spoiler

I had girlfriend who worked as a psychotherapist; she saw me soldering pixels onto a sign. One day, a client of hers—a worker from a printer repair shop—came and started complaining about his life: this is bad and that is bad—everything is bad; things are going badly ever at work, and nothing is soldering the way it should. The guy was shocked when the psychotherapist with complete artlessness asked, "Do you heat the solder joint thoroughly? What kind of flux do you use?"