Hi guys been a while!
well i was diving in to these style of planar magnetics. (mainly because of the ability of low resonance) because i wanted to make something that could be used with my planar magnetics bas/mid panels that sounds better or with a dynamic woofer (so efficiency is s thing) and since i buy a shitload of magnets with one of the members here 🙂
so i made a small tester first since i did not have enough magnets to go beserk.
Part one : Building one
Part Two : a tune with the 1 version i got and some measurements
Part 3 : another tune but now with 2 and some adjustments i would like to make.
greetings Joppe
well i was diving in to these style of planar magnetics. (mainly because of the ability of low resonance) because i wanted to make something that could be used with my planar magnetics bas/mid panels that sounds better or with a dynamic woofer (so efficiency is s thing) and since i buy a shitload of magnets with one of the members here 🙂
so i made a small tester first since i did not have enough magnets to go beserk.
Part one : Building one
Part Two : a tune with the 1 version i got and some measurements
Part 3 : another tune but now with 2 and some adjustments i would like to make.
greetings Joppe
It would be great if you and/or others could list the tools needed to cut the aluminum traces, tension, adhesives used, and test procedures for resonant response/sweep. Don't be afraid to list the tools based on cost. Your CNC cutter looks like a needed device. Do we tension based on modulus of elasticity? A percentage of this, and what tools are used for tensioning.
As a thought; could tensioning be accomplished by trapping the Kapton in a groove as the 2 halves are mated and stretch the membrane. One side would have a rubber o-ring to push the Kapton/Mylar into the mating side groove of the other half. Self tensioning can be accomplished with this method if the initial set-up was done properly. The calculations for stretch based on the width and length could be determined and then machine the groove.
This is similar to what we all do when replacing the screen in the frame. Same principal applies. As you roll the piping into the frame and work it around the perimeter, the screen becomes taut. Maybe just roll piping around the cut groove and mate the 2 halves together for a completed rebuild.
This is a way to be able to service the 2 halves and possibly re-stretch the diaphragm in the future. I can machine the groove for the o-ring if needed in the OEM plate.
This seems like a repeatable process if someone wants to rebuild their planer diaphragm.
Thoughts everyone??
MAK
As a thought; could tensioning be accomplished by trapping the Kapton in a groove as the 2 halves are mated and stretch the membrane. One side would have a rubber o-ring to push the Kapton/Mylar into the mating side groove of the other half. Self tensioning can be accomplished with this method if the initial set-up was done properly. The calculations for stretch based on the width and length could be determined and then machine the groove.
This is similar to what we all do when replacing the screen in the frame. Same principal applies. As you roll the piping into the frame and work it around the perimeter, the screen becomes taut. Maybe just roll piping around the cut groove and mate the 2 halves together for a completed rebuild.
This is a way to be able to service the 2 halves and possibly re-stretch the diaphragm in the future. I can machine the groove for the o-ring if needed in the OEM plate.
This seems like a repeatable process if someone wants to rebuild their planer diaphragm.
Thoughts everyone??
MAK
Well i dont mind, For cutting traces you can use a cnc like i do or often you can use a cheap plotter like the Cameo. i myself have no experience with these and since i cut my foil apply mylar then cut the whole thing free i think a flat bed plotter or a modded CNC like i use would be beneficial. it does not have to be as sturdy as a cnc. you can easilly make a machine using belt drive and unsupported shafts etc (my plan for a LOOONG plotter with minimal investments 🙂 )
in the panel seeen above there is no tension (hardly) 🙂 thats the beauty of it. you corugate the foil. then tension it vertical (just pull on the corrugated foil, nothing like a normal planar). this can be a percentage of the foil.. so corugating then tension towards the panel size. and you should get the same tension everytime. so i make a foil 10% longer usually (not sure if this is the correct added foil) after its stretched i can then pull it to fit the frame.
in this case its not tensioned side ways , its caught by the Foam strip on the back of the pannel and the front baffle. this way the foam will for conform to the corrugation. and keeps the foil there without tensioning it.
hope that helps ?
I am looking to rebuild the RD48 from BG. The ribbon is not corrugated. It looks like the NEO 10 is stretched and glued to a frame. Has anyone taken the 48 to 75 inch BG planer apart and shared pictures?
Mark
Mark
The bg's are put together with rivets you would have to drill them out with a drill thats about the same size as the holes, and replace them with bolte and nuts. Then you can do like in this youtube video. I know its not a bg, but the princip are the same. There is no other way to do it if you want to find the problem. Do not worry its not rocket science 🙂
Found someone that did it. They look like the old Strathearn planar.
https://www.avnirvana.com/threads/repair-of-50-bg-ribbon-driver.6878/
https://www.avnirvana.com/threads/repair-of-50-bg-ribbon-driver.6878/
Yes also called Stratec 🙂 they look exactly the same 🙂 2 or 4 traces. no corrugation 🙂
Only ordinary ferrite magnet no samarium-cobalt!
I would not invest any work here because these are the ones which have tons of distortions (I already warned you about these many years ago here on this board) if you use normal pink noise (Hifi Test CD , not MP3 yunk from the web) 1/3rd octave wide , and low volume . No matter which frequency or which level , these junk magnetostats just distort heavily , your ears will tell you 🙂
Put a resistor in series for testing , no need for a transformer!
good luck (you will need it)
I would not invest any work here because these are the ones which have tons of distortions (I already warned you about these many years ago here on this board) if you use normal pink noise (Hifi Test CD , not MP3 yunk from the web) 1/3rd octave wide , and low volume . No matter which frequency or which level , these junk magnetostats just distort heavily , your ears will tell you 🙂
Put a resistor in series for testing , no need for a transformer!
good luck (you will need it)
Hello Marvel,
You are specifically referring to the HiFiSound and Streathern contraptions in post 10? I owned the original Streahtern/Infinity modules. Catastrophic construction: on the various shipments from mr. R.F.R. Dowling, nr. 3 Bachelors Walk in Lisborne (heh, how's that for memory?) at least half were destroyed because the magnets had come loose.
You are specifically referring to the HiFiSound and Streathern contraptions in post 10? I owned the original Streahtern/Infinity modules. Catastrophic construction: on the various shipments from mr. R.F.R. Dowling, nr. 3 Bachelors Walk in Lisborne (heh, how's that for memory?) at least half were destroyed because the magnets had come loose.
Yes , way back in the past I got some of these in visually good condition for low money but no step-up transformers included so I used a high power resistor in series to the "SC-III" ribbon , but mechanically it is a planar/magnetostatic transducer .
Later I got 6 of the original toroid transformer from PIKATRON , sold by Mr. Saerbeck Hifisound for a low price in perfect condition in original package looking as they were new ones .
But they appeared as being defective all of them! The had massive isolation problems and impedance got sometimes down some tenths of an ohm!
So I used a resistor of 1.5 ohm in series instead of a transformer , accepting the lower SPL and impedance of exactly 1.85 Ohm in total at normal room temperature of 23 degree Celsius .
Later I got 6 of the original toroid transformer from PIKATRON , sold by Mr. Saerbeck Hifisound for a low price in perfect condition in original package looking as they were new ones .
But they appeared as being defective all of them! The had massive isolation problems and impedance got sometimes down some tenths of an ohm!
So I used a resistor of 1.5 ohm in series instead of a transformer , accepting the lower SPL and impedance of exactly 1.85 Ohm in total at normal room temperature of 23 degree Celsius .
At some time the owner of Hifisound (hifisound.de) Mr. Saerbeck offered an upgrade for this pseudo-ribbon transducer consisting of a complete new foil with more traces/conductors so the DC-Resistance rises from 0.385 Ohm (typical) to 2.4 Ohm (not measured by me just the data sheet value from my memory) . I think the foil itself changes too from 6um mylar to Kapton of unknown thickness . Damping material has changed too but no info about that . Upgrade charge was 400 Deutsche Mark , half the price of the single driver without transformer . The transformer was not longer needed when using the upgraded version ....
Off topic, but: wasn't the fellow that was the co-owner of Hifisound mr. Morava or something like that? Been a few times in the shop in Munster, and still have one of their hardcopy catalogues.
Search google for Saerbeck & Morava , and translate the website :
https://www.lowbeats.de/hifisound-muenster-der-online-hifi-pionier/
https://www.lowbeats.de/hifisound-muenster-der-online-hifi-pionier/