looking specifically at Radian:
https://radianaudio.com/collections/ribbon/products/lm8k-wide-band-planar-ribbon-transducer
it says the conductor material is "aluminum foil"
but aluminum is a material that suffers from fatigue when repeatedly bent. in a planar the "voice coil" and the "suspension" are the same part - so you now pretty much have aluminum suspension. the only other drivers i can think of that have aluminum suspension is Beyma Bullet Supertweeters ...
but Beyma Bullets have replaceable diaphragms, in fact i replaced it on mine ( due to issues unrelated to aluminum fatigue ). it doesn't seem like you can replace the diaphragm in a Radian driver.
would this be a cause for concern in a high SPL application ?
does GRS planar also use aluminum foil or do they use copper ?
does it make a difference for durability ?
thoughts ?
EDIT: i should add that Beyma Bullets have recommended frequency range of 5khz and up, while the Radian is recommended down to 250 hz so it would probably see a lot more bending of the diaphragm, though that's just a guess, not scientific analysis.
https://radianaudio.com/collections/ribbon/products/lm8k-wide-band-planar-ribbon-transducer
it says the conductor material is "aluminum foil"
but aluminum is a material that suffers from fatigue when repeatedly bent. in a planar the "voice coil" and the "suspension" are the same part - so you now pretty much have aluminum suspension. the only other drivers i can think of that have aluminum suspension is Beyma Bullet Supertweeters ...
but Beyma Bullets have replaceable diaphragms, in fact i replaced it on mine ( due to issues unrelated to aluminum fatigue ). it doesn't seem like you can replace the diaphragm in a Radian driver.
would this be a cause for concern in a high SPL application ?
does GRS planar also use aluminum foil or do they use copper ?
does it make a difference for durability ?
thoughts ?
EDIT: i should add that Beyma Bullets have recommended frequency range of 5khz and up, while the Radian is recommended down to 250 hz so it would probably see a lot more bending of the diaphragm, though that's just a guess, not scientific analysis.
Grs is aluminium too, they all are. Copper would be too heavy.
Planars should move like piston, not as bending wave. There is no aluminium surround in planars.
250Hz is optimistic, they will distort crossed that low. 900Hz is what i use.
They only last till you overload them. That means thermal breakdown, open circuit.
Planars should move like piston, not as bending wave. There is no aluminium surround in planars.
250Hz is optimistic, they will distort crossed that low. 900Hz is what i use.
They only last till you overload them. That means thermal breakdown, open circuit.
The conductor material for the coils is aluminum, but the backing material is usually kapton or mylar. The aluminum coils are moved in a planar fashion so most of the elastic deformation is done by the backing, or mylar / kapton.
But note also that aluminum can be elastically deformed. Note that most metals have an elastic region where they can be bent and then if the stress is released then they return to the original state, and then a plastic region where if you bend that far it then it stays bent.
Planar membranes, while moving to create sound, all stay in the elastic region so even if the aluminum is bent, it is not bent permanently. If it did, then as you write then it would break.
Ive done tests of the durability of foil vs foil laminated to foil vs foil laminated to various plastic films. The durability of the laminates is FAR superior to foil only. Did some development work a while ago on a foil only bass diaphragm. They all showed cracks eventually. However when it was made from 2 layers of foil with visco elastic sandwiched between they lasted forever. It was an HUGE difference
Along with this the planer membranes movements are small enough that its really a non issue.
Along with this the planer membranes movements are small enough that its really a non issue.
are there any drivers like that with foil on both sides of film ?
BMS makes compression tweeters with inside-outside wound voice coils.
i also wonder if having the foil on the cabinet side versus room side would make a difference in thermal power handling.
probably negligible ...
Indeed ! I had forgotten about this !
i guess then the answer is ribbon will last forever if not abused.
however for Prosound application ( which Radians are ostensibly for ) they really should make the ribbon element replaceable, because some drunk guy will surely connect the ribbon to the subwoofer amp or something.
even RAAL has replaceable ribbon, and it is not targeting prosound.
Electric Cars need neodymium for their motors. We can't just be recklessly tossing neodymium drivers in the trash simply because an $1 piece of plastic film / foil got toast.
Even for home use i would have preferred replaceable diaphragm but for Prosound i would absolutely demand it.
Every single compression driver and bullet supertweeter has replaceable diaphragm and woofers can be reconed.
I honestly think Radian as a brand is somewhere between consumer and professional markets. i don't think of them as full on professional like RCF or something. i prefer fully professional everything but a fully professional array would use compression drivers with V-Dosc adapters and that would almost certainly be more colored than a ribbon, not to mention more expensive and i would never be able to use even 1% of the output.
ultimately ribbons are a hack. the future is ring radiators with V-Dosc type adapter but instead of converting a ring to a circle and then to a line it would go straight from ring to a line like a slot supertweeter does, but for midrange.
i mean picture a Beyma CP21 but instead of 1.5" aluminum supertweeter diaphragm a 3.5" plastic diaphragm from BMS Midrange.
that's the future. but it's not here yet. it seems Radian ribbon is the best we have for now.
i mean picture a Beyma CP21 but instead of 1.5" aluminum supertweeter diaphragm a 3.5" plastic diaphragm from BMS Midrange.
that's the future. but it's not here yet. it seems Radian ribbon is the best we have for now.
"ultimately ribbons are a hack."
Hmmm , I would like to hear more on that statement. What do you mean here?
Also what do you mean when you use the term "ribbon". Ive done a lot of ribbon development and the way the term "ribbon" is used is more often than not misleading at best.
Planer magnetics are not ribbons. They are constructed quite differently and have different strengths /weaknesses
in fact it seems to me the use of the term "ribbon" when talking about planer magnetics is a hack or sorts
Hmmm , I would like to hear more on that statement. What do you mean here?
Also what do you mean when you use the term "ribbon". Ive done a lot of ribbon development and the way the term "ribbon" is used is more often than not misleading at best.
Planer magnetics are not ribbons. They are constructed quite differently and have different strengths /weaknesses
in fact it seems to me the use of the term "ribbon" when talking about planer magnetics is a hack or sorts
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i mean that i can always design an array of compression drivers to outperform any ribbon in every way.
but it's 10 times cheaper to just use a ribbon.
so it's a hack.