MAB
Major Contributor
I have an old pair of Realistic Minimus-7 speakers. They were from the previous owner of our house, installed as outdoor speakers. They spent 30+ years under an awning. I removed them from the outdoor spot a few years ago and put them aside, they were in surprisingly decent shape despite being covered in dirt and cobwebs. I got the pair out of storage and decided to take some measurements, see if they match previously published data. For instance Archimago's excellent review:
archimago.blogspot.com
The Minimus-7 was introduced in 1978:
There are a bunch of iterations. My pair are 40-2030C, which I believe are from the mid '80s. Archimago's test is an earlier version.
Here they are, just out of storage:
There isn't much to them except slick design:
Once you have them apart, I recommend washing them with soap and water.
The tweeter LC network uses a 0.4mH inductor and a 4.7uF capacitor.
The woofer has no filter.
The individual driver measurements in free-air; woofer on left, tweeter on right:
The woofer has some evidence of resonances, the impedance slope varies starting at ~2kHz. The tweeter is odd with a double-peak.
Prior to disassembly I had measured both speakers' on-axis frequency response in my room. Both of the speakers are closely matched, small 1dB difference at the 3.5kHz resonance, but within 0.5dB over the rest of the frequency range.
I took horizontal and vertical measurements of the speaker at 1 meter on a turntable in 10 degree increments. These measurements were with the grille on. These were merged with nearfield measurements of the woofer using VituixCAD:
Bass rolls off below 200 Hz, large peak at 3.5kHz. I have never liked the sound of the Minimus 7. The midrange hump is difficult. The lack of bass and upper treble exacerbates my dislike. That being said, I am awestruck that after 30 years outdoors in the Pacific NW the measurements indicate the speakers work as Minimus 7 should. And sound similar to others I recall.
This measured result is similar to older measurements I have seen of the 40-3030C model, for example:
Archimago's test of the earlier version of the Minimus 7 has slightly better bass extension, similar 3.5kHz treble peak.
All of the various models need to reduce the level and integrate the tweeter differently, it's ridiculous! The peak at 3.5kHz sticks out like a sore thumb being right near the crossover frequency where the directivity is also changing rapidly. Even worse sounding with no bass. It's very distracting to listen to.
The resulting horizontal and vertical directivity plots are similar to Archimago's as well:
Where is that peak coming from? The tweeter.
Rich in odd HD at 3.2kHz, the tweeter's peak is a distortion machine! In a compression test you can see it actually result in positive compression at high volume due to energy sprayed in the tweeter's distortion components!
The woofer is a bit ragged with resonances above 2kHz at the same frequencies the blips in the impedance slope occur:
The tweeter and the woofer are perhaps competing to make the midrange bad.
I know there are some simple proposed tweaks for the Minimus 7. A better crossover that lowers the tweeter level, and reduces the peak. And a crossover for the woofer. The industrial design is fantastic. And the speakers are incredibly weatherproof, durable, and look good. Taming the tweeter/midrange crossover point would help make them completely appealing.
RETRO-MEASURE: Radio Shack / Realistic / Tandy Minimus 7 speakers (early 1980s, Cat. No. 40-2030A)
A blog for audiophiles about more objective topics. Measurements of audio gear. Reasonable, realistic, no snakeoil assessment of sound, and equipment.
archimago.blogspot.com
The Minimus-7 was introduced in 1978:
There are a bunch of iterations. My pair are 40-2030C, which I believe are from the mid '80s. Archimago's test is an earlier version.
Here they are, just out of storage:
There isn't much to them except slick design:
Once you have them apart, I recommend washing them with soap and water.
The tweeter LC network uses a 0.4mH inductor and a 4.7uF capacitor.
The woofer has no filter.
The individual driver measurements in free-air; woofer on left, tweeter on right:
The woofer has some evidence of resonances, the impedance slope varies starting at ~2kHz. The tweeter is odd with a double-peak.
Prior to disassembly I had measured both speakers' on-axis frequency response in my room. Both of the speakers are closely matched, small 1dB difference at the 3.5kHz resonance, but within 0.5dB over the rest of the frequency range.
I took horizontal and vertical measurements of the speaker at 1 meter on a turntable in 10 degree increments. These measurements were with the grille on. These were merged with nearfield measurements of the woofer using VituixCAD:
Bass rolls off below 200 Hz, large peak at 3.5kHz. I have never liked the sound of the Minimus 7. The midrange hump is difficult. The lack of bass and upper treble exacerbates my dislike. That being said, I am awestruck that after 30 years outdoors in the Pacific NW the measurements indicate the speakers work as Minimus 7 should. And sound similar to others I recall.
This measured result is similar to older measurements I have seen of the 40-3030C model, for example:
Archimago's test of the earlier version of the Minimus 7 has slightly better bass extension, similar 3.5kHz treble peak.
All of the various models need to reduce the level and integrate the tweeter differently, it's ridiculous!
The peak at 3.5kHz sticks out like a sore thumb being right near the crossover frequency where the directivity is also changing rapidly. Even worse sounding with no bass. It's very distracting to listen to.The resulting horizontal and vertical directivity plots are similar to Archimago's as well:
Where is that peak coming from? The tweeter.
Rich in odd HD at 3.2kHz, the tweeter's peak is a distortion machine! In a compression test you can see it actually result in positive compression at high volume due to energy sprayed in the tweeter's distortion components!
The woofer is a bit ragged with resonances above 2kHz at the same frequencies the blips in the impedance slope occur:
The tweeter and the woofer are perhaps competing to make the midrange bad.
I know there are some simple proposed tweaks for the Minimus 7. A better crossover that lowers the tweeter level, and reduces the peak. And a crossover for the woofer.
The industrial design is fantastic. And the speakers are incredibly weatherproof, durable, and look good. Taming the tweeter/midrange crossover point would help make them completely appealing.
Last edited:
Gads. I have at least two 'salvaged from an original four. Not sure why.. Thought of 'repair, maybe up grade'.. Oops.
