Nice acquisition!
Measurements were made with the “naked” driver mounted to a slender stick.
I did this for my own selfish reasons to make comparison with BTM diffraction theory easier.
The only felt damping I noticed was a thin layer mounted to the rear magnets. Is that what you were talking about?
Or, do some versions have some additional felt between the driver and the rear grill.
The thin felt made surprisingly little difference to the HF response as the front .vs. rear response comparison plot shows.
I also attached a near field measurement showing two diaphragm resonance modes that I thought you might find interesting.
Attachments
Add the MH-502 and the PM-9, and that makes 5 versions.
I think both of these use non-plated magnets, so should not have a problem with corrosion of plating leading to buzzing. PM-9 is also held together with screws for simple disassembly if needed.
I have recently acquired a pair of PM-9 and looking at redesigning the accompanying bass section for them.
Thanks Bolserst for the curves!
Attachments
The pd ribbob in the MH-502 is much smaller and used as a tweeter with a 2.5” midrange. Woofer is a 4” (meaures across 10+ units show a high level of variability.
dave
dave
I worked at the bioacoustics lab at the University of Pittsburgh for several years, researching, among other things, presbycusis (age related hearing loss). Typical loss at 6,000 Hz in an 80 year old is around 40 dB, higher if you've worked in a noisy environment. I assumed you were in this age range from a signature, "HiFi aspirations since 1957."
As to the frequency range of instruments, it is common knowlege in the recording industry, (where I've also worked) than many instruments extend well past 20K, let alone 6K. Muted trumpets put out strong energy out to 80K, as anyone who has mastered a record knows. Lowmass, here's an informative article on the range of musical instruments: There's life above 20 kilohertz! A survey of musical instrument spectra to 102.4 kHz
As you can see, there's a lot up there!
All of the Monsoon ribbons from 1st gen to 3rd gen have unplated ferrite magnets — i have disassembled them all.
dave
dave
But that's not a problem AFAIK. Unplated ferite doesn't crumble into dust over time like the samarium cobalt magnets in my old Infinity 2.5s did after the plating failed.
Maybe you mean 2nd gen? Because the MM-1000 f.ex. had nickel plated magnets and could turn to dust.
They sure do look like the big Monsoon panels.
Eastech in Malaysia bought Monsoon just to get the Eminent Technology licencing aggreements for th eribbon tech… the patent may well have expired by now.
dave
An externally hosted image should be here but it was not working when we last tested it.
Eastech in Malaysia bought Monsoon just to get the Eminent Technology licencing aggreements for th eribbon tech… the patent may well have expired by now.
dave
The Monsoon panels worked to below 1kHz though.
The "RD1000" looks a LOT like one of the Bohlender-Graebener long magnetic planar lines.
The "RD1000" looks a LOT like one of the Bohlender-Graebener long magnetic planar lines.
The big Monsoom panels were used to just a bit over 200 Hz. A 6 dB/octave filter (boost) below 1 kHz compensated for the dipole rolloff.
dave
dave
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