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Genesis ribbon tweeter as headphone driver

post #1 of 13
Thread Starter 
Figured I'd first ask familiars here before posting on a speaker forum....

Anyone here know about the Genesis 1" "ribbon" tweeter and how it works?

I've tried diy ribbons before, but this tweeter is round. Having a hard time figuring out how the voice coil and flux are oriented.

Here's the company link
http://www.genesisloudspeakers.com/t...ontweeter.html

Closeup of a friend's 1.1 tweeter
Note: all the tweeters have a slight wrinkle to them.
http://24.99.95.78/public/image/wenl/IMG_0125.JPG
post #2 of 13
How would you get low frequencies?
post #3 of 13
hard to say.... you'd have to try it out. Speaker freq response is measured with a calibrated mic, they drive the speaker with 1W of pink noise with the mic placed at 1 meter away, on axis to the voice coil.

Hard to say how it would sound located flat up against the ear, slightly off axis to the ear. The Infinity Emit (car audio) ribbon tweeters Ive listened to placed right up next to my ears have always been filtered at ~4000 Hz. Not sure how they'd respond to a full range scenario?

Another thing.... headphone drivers do not move in a linear / piston fashion. They are thin mylar or plastic and they "flap", in very irregular motions. I think different areas on the surface of the cone resonate at different frequencies to produce the full spectrum. I dont think ribbon tweeters behave the same way. Typically tweeters are intentionally designed for a very limited bandwidth.

Some of these might be better:
http://www.partsexpress.com/webpage....=576&sm=1&so=2

Hive it a shot... who knows till you try????

Garrett
post #4 of 13
Fostex headphones used to use round shaped ribbon speakers in their headphones and tweeters. The pics in this thread might help you...

http://www6.head-fi.org/forums/showp...83&postcount=1
post #5 of 13
The speaker is essentially the same as a Magneplanar speaker - as invented by Winey. The voice coil is what you see - an etched spiral on the membrane. The magnet is a rare-earth type with its pole facing out. It isn't what purists would regard as a true ribbon.

Intrinsically there is no real reason why these could not be a full range driver. All drivers have a very wide frequency "response" (i.e. frequencies at which they do something). But you would need to equalise it very substantially in order to get a flat response. This essentially means attenuating all the higher frequencies to the point that they are dropped to the very low level that the bass ones are reproduced. This may turn out to be unfeasible - or result in a system with totally unusable efficiency or output levels. After all there was never any intent by the designer that it be used this way. There very well may be system resonances at unfortunate frequencies, again not an issue when used as a tweeter, but possibly making use as a full range driver impossible, or very difficult.
post #6 of 13
Thread Starter 
Francis, can you please expand on how the magnets are oriented?
This is the only way I see the EMF oriented w/ the voice coil (which is actually a spiral) to produce pistonic motion. However, it means a small magnet in the middle and a ring magnet around the perimeter?



You're right about the designed parameters and resonance. My diy ribbons in the past always had a high resonance freq. And with very little tension (for bass respones) they went wild at that freq.

tyre, creyc
Thanks for the Fostex link. Very cool driver. I wonder if the seperate "subsections" are an attempt to break up diaphragm resonance.

I wouldn't really use the actual genesis tweeter. First of all, don't think I have the funds (that system is $145k for Christ sakes). I meant to use the same design, and apparently, the Fostex does just that.

I'm hoping the trump card for lack of bass is a tight/sealed coupling with the head. That's one advantage we have vs the speaker guys, though it might introduce some standing wave problems.


Quote:
Originally Posted by kramer5150
I think different areas on the surface of the cone resonate at different frequencies to produce the full spectrum.
Would be interesting to get a laser vibrometry of a HD650 driver for ex. It sounds like you're saying it works in a similar fashion to a Soundlabs ESL? Different resonance frequencies combine for a flat response. However, a soundlab esl has well defined sections of resonance. It would be difficult to produce such defined sections of resonance with a simple dome shape. Seems to me a (single material, same thickness, dome-shaped) headphone driver would have one or two prounounced peaks rather than evenly distributed resonance points?


PS:
Here's the system that tweeter came from btw (one of many )
post #7 of 13
thats just absurd!
post #8 of 13
Hi hozo
Good to see you are still up for more diy phones.
Though I doubt that tweeter is capable of much excursion considering it's
intended frequency range.

I have not dabbled in the black arts for some time, but have been
contemplating the 'purist' aluminum ribbon approach again.
But that would mean a dedicated amp to drive the ridiculously low
impedance if the ribbons.
The planar coil approach is a lot more amp friendly!

Still enjoying those wonderful electrostatic creations of yours?

[Tame your ribbons flapping bass peak with a notch filter,works wonders ]


.
post #9 of 13

Did someone say ribbon tweeter?

post #10 of 13
Thread Starter 
familyman,
Can you give more info about that ribbon driver? Five rows of magnets? Commercial, DIY?

setmenu,
Of course, diy drivers forever! The worst rattles of your own driver is sweeter than the singing of any commercial driver... ok maybe not.

I was just about to seek your advice/experience on ribbons and etched diaphragms. I saw some 12 micron aluminum foil at mcmasters. Online sources are also popping up for strong magnets unlike few years ago.

Of all the operational differences between electrostats and true ribbons, I glossed over a key difference: tensioning. With ribbons, corrugation makes it not as important to a DIYer. The frame needs minimal force to keep a ribbon in the EMF. With (headphone sized) electrostats, tension is the key to diaphragm collapse, sensitivity, bass, treble, and just about everything else.

I'm still working on electrostats, but I'm thinking it's time to get an Omega II for reference. ehem. yes, reference purposes.



Quote:
Originally Posted by setmenu
Tame your ribbons flapping bass peak with a notch filter,works wonders
thanks for the tip. I'll give that a try. Probably better than foam dampening.
post #11 of 13
Quote:
Originally Posted by hozo
Francis, can you please expand on how the magnets are oriented?
This is the only way I see the EMF oriented w/ the voice coil (which is actually a spiral) to produce pistonic motion. However, it means a small magnet in the middle and a ring magnet around the perimeter?



You're right about the designed parameters and resonance. My diy ribbons in the past always had a high resonance freq. And with very little tension (for bass respones) they went wild at that freq.

tyre, creyc
Thanks for the Fostex link. Very cool driver. I wonder if the seperate "subsections" are an attempt to break up diaphragm resonance.

I wouldn't really use the actual genesis tweeter. First of all, don't think I have the funds (that system is $145k for Christ sakes). I meant to use the same design, and apparently, the Fostex does just that.

I'm hoping the trump card for lack of bass is a tight/sealed coupling with the head. That's one advantage we have vs the speaker guys, though it might introduce some standing wave problems.




Would be interesting to get a laser vibrometry of a HD650 driver for ex. It sounds like you're saying it works in a similar fashion to a Soundlabs ESL? Different resonance frequencies combine for a flat response. However, a soundlab esl has well defined sections of resonance. It would be difficult to produce such defined sections of resonance with a simple dome shape. Seems to me a (single material, same thickness, dome-shaped) headphone driver would have one or two prounounced peaks rather than evenly distributed resonance points?


PS:
Here's the system that tweeter came from btw (one of many )

You'd think the guy could afford a head!
post #12 of 13
Thread Starter 
That's me right there .

Not my system of course. It sounded ok.
post #13 of 13
Quote:
Originally Posted by hozo
familyman,
Can you give more info about that ribbon driver? Five rows of magnets? Commercial, DIY?

setmenu,
Of course, diy drivers forever! The worst rattles of your own driver is sweeter than the singing of any commercial driver... ok maybe not.

I was just about to seek your advice/experience on ribbons and etched diaphragms. I saw some 12 micron aluminum foil at mcmasters. Online sources are also popping up for strong magnets unlike few years ago.

Of all the operational differences between electrostats and true ribbons, I glossed over a key difference: tensioning. With ribbons, corrugation makes it not as important to a DIYer. The frame needs minimal force to keep a ribbon in the EMF. With (headphone sized) electrostats, tension is the key to diaphragm collapse, sensitivity, bass, treble, and just about everything else.

I'm still working on electrostats, but I'm thinking it's time to get an Omega II for reference. ehem. yes, reference purposes.




thanks for the tip. I'll give that a try. Probably better than foam dampening.

Hi Hozo
The first ribbon experiments i made were simply kitchen foil strips between two magnets.
I then moved onto etched coils using flexible laminates.
Flexi laminate manufactures to look out for are Espanex and Toray.
Both of these make ahesiveless laminates, adesiveless is important to save
weight and reduce stiffness.
The thinest Laminate I have used was a sample of espanex which was
something like 12 micron of copper on 12 of polymide.[can't remember exact
figures]

The Toray product can offer 1-18 micron copper on 12 of polymide.
The main problem with these thinest laminates is getting hold of samples.
Generally one has to purchase a whole reel at many thousands of $$$$$$$$!
I was lucky to get the espanex, but had no luck with the Toray.
Perhaps you will be more fortunate and find a source of small samples.

The above makes using simple plain aluminum ribbons very appealing.
Well from a manufacturing perspective,driving them is another ball game
compared to the etched coil, they can be driven reasonably well by my portable amp.

I look forward to seeing your first ribbon transducers.


.
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