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post #511 of 5003
Thread Starter 
Quote:
Originally Posted by EddieE View Post

Quote:

Originally Posted by wallace View Post

The cups were some of the first made by Nickchen when he got his lathe,i expect his current work is even better,as long as his better half has not objected to him spending his spare time in the cellar.wink.gif.


You expect quite right - there are the cups he recently did for me:

 

1000x500px-LL-317d5a1b_IMG_0916.jpg


Awesome work!

post #512 of 5003

Hah, were you looking at the K&J catalog?

 

Hmm, are you going to start tinkering with different driver magnets now? Maybe stronger magnets = better sound? (more power! *grunt*grunt*grunt*)

post #513 of 5003

I mentioned this in another thread somewhere. Have you ever tried flipping the drivers around in the cups? I've sometimes felt that Grados were almost louder on the backside than the front. My experiences with some speakers has also been that they sound better when pointed away and reflect off a wall back at me. Maybe a closed grado with reversed drivers could be interesting...?

post #514 of 5003

I have a sneaky feeling you are about to suggest that i make a pair of phones from whatever i can find in my workshop,ie two washers and some ducktape.plus some carefully wound copper wire.Best stop whilst i am ahead..Ha Ha..

post #515 of 5003

If the magnet is the next thing to play with bilavideo, how about investigating a donut magnet and magnet plate like the HD800/T1 have - would surely be a big advancement when it came to dealing with backwave?

 

By the way, I know I've said this to you before on this thread, but keep doing what you're doing, this is thread is in my top five all time, all forum threads. Great to read one man's quest to squeeze every bit of life out of a simple headphone design.

post #516 of 5003

Hey Bilavideo, the "cage" for the magnets has two holes already, but what would happen if you were to add another hole or two? I think that would be an easier experiment than replacing the driver magnet completely.

post #517 of 5003

More holes would be interesting. One thing I'll say is that covering those holes makes no audible difference to the sound, but adding more just might...

post #518 of 5003

Or if the backplate is simply there to hold the magnet... how about replacing it with something else?

 

Adding some more holes might be interesting, but I'd worry about the plate losing stiffness, which would make it vibrate more and reduce the effectiveness of the driver. After all, the voice coil is what moves relative to the magnet, which in theory should not move at all. I think the holes are there simply to vent pressure, so covering them might not be a good idea. Now that I think about it, we've gone through all this talk about modifying the chambers and damping yadda yadda, but not enough on improving the mechanical response of the driver. What can we do to reduce that plate vibration?

 

- blob of damping material on the back, which adds mass (and the blog will reduce back emanations from the driver, or at least give it an uneven surface so backwaves will be scattered)

- stiffen the backplate... not easily accomplished

- add mass

- mechanically couple the backplate (theoretically similar to adding mass, but on a larger scale)

 

How about just simply sticking another magnet on the back of the plate? That should increase overall magnetic field strength and provide a significant mass increase to reduce vibrations.

 

Man, I really wish I had a grado to experiment with right now. Heck, I have a stack of appropriate sized rare earth magnets sitting right next to me...

post #519 of 5003
Quote:
Originally Posted by Armaegis View Post

Or if the backplate is simply there to hold the magnet... how about replacing it with something else?

 

Adding some more holes might be interesting, but I'd worry about the plate losing stiffness, which would make it vibrate more and reduce the effectiveness of the driver. After all, the voice coil is what moves relative to the magnet, which in theory should not move at all. I think the holes are there simply to vent pressure, so covering them might not be a good idea. Now that I think about it, we've gone through all this talk about modifying the chambers and damping yadda yadda, but not enough on improving the mechanical response of the driver. What can we do to reduce that plate vibration?

 

- blob of damping material on the back, which adds mass (and the blog will reduce back emanations from the driver, or at least give it an uneven surface so backwaves will be scattered)

- stiffen the backplate... not easily accomplished

- add mass

- mechanically couple the backplate (theoretically similar to adding mass, but on a larger scale)

 

How about just simply sticking another magnet on the back of the plate? That should increase overall magnetic field strength and provide a significant mass increase to reduce vibrations.

 

Man, I really wish I had a grado to experiment with right now. Heck, I have a stack of appropriate sized rare earth magnets sitting right next to me...


The metal covering is nonmagnetic. The magnets are glued into the metal covering. There is a slight magnetism through the back plate, but not enough to hold a magnet in place. Replacing the magnets would be a more viable option.

 

EDIT: Also, Bilavideo, there aren't two magnets, there is only one. the smaller magnet is the only magnet in the assembly, the other just sticks to it. 


Edited by BobSaysHi - 12/20/10 at 2:56pm
post #520 of 5003
Quote:
Originally Posted by BobSaysHi View Post

The metal covering is nonmagnetic. The magnets are glued into the metal covering. There is a slight magnetism through the back plate, but not enough to hold a magnet in place. Replacing the magnets would be a more viable option.

 

 


Really? the rare earths are rather strong, even with a nonmagnetic plate in between them I figured there would be enough force to hold them together. How about just glue a washer or coin to the back then? (I suppose you could blue-tac or hot glue it, but then you'd still have that squishy layer in between which would allow the plate to vibrate)

post #521 of 5003
Thread Starter 

 

Originally Posted by Armaegis View Post

Hah, were you looking at the K&J catalog?  Hmm, are you going to start tinkering with different driver magnets now? Maybe stronger magnets = better sound? (more power! *grunt*grunt*grunt*)


I'm interested in building my own drivers.  The drivers are just magnets, voice coils, diaphragms and a plastic basket.  The magnets are freely available.  The baskets could be built from wood or carbon fiber.  The voice coils use thread-like bare copper wire that has to be wound the right number of loops.  The diaphragms, by and large, are just Mylar, which is DuPont's trademarked name for plastic film.  From everything I've read, this material is used, not for its magical qualities but because it's cheap.  Those shrimp-platter radial ridges are there to give rigidity to something incredibly flimsy.  They also damp the vibrations that cause center-cone break-up.

 

I'm not in a position to press, stress or de-stress Mylar, which will remain a challenge, but I'm curious about what could be done with this potato-chip-bag material, which can be ordered in sheets of different weights.  Sennheiser's innovation, for the HD800, was to create a doughnut with no center cone to break up, powered by a ring magnet.  That's great.  But why stop there?  Sennheiser's 56mm driver stands out among designs, though I'm not sure how big it really is when you subtract for the center that isn't there.  I don't expect to reinvent civilization, itself, but if the driver is the one part of the headphone that is actually replicating the wave forms in the recording, why settle for a flimsy 40mm driver made from cheap plastic?  Is this the zenith of head fidelity?  If not, why not push the envelope?

 

 

Originally Posted by Armaegis View Post

I mentioned this in another thread somewhere. Have you ever tried flipping the drivers around in the cups? I've sometimes felt that Grados were almost louder on the backside than the front. My experiences with some speakers has also been that they sound better when pointed away and reflect off a wall back at me. Maybe a closed grado with reversed drivers could be interesting...?

 

I've started experimenting with driver angles to look at how off-axis sound affects perceptions of space.  I know that Ultrasone uses S Logic but after looking at what it does, I'm more inclined to go in a different direction.  I'm not interested in a hard plate with a series of holes and felt-covered bass vents.  If it works, all power to it but I'm looking in a direction directly - literally.
 

Originally Posted by wallace View Post

I have a sneaky feeling you are about to suggest that i make a pair of phones from whatever i can find in my workshop,ie two washers and some ducktape.plus some carefully wound copper wire.Best stop whilst i am ahead..Ha Ha..

 

When I got into Homemade IEMs, it was because I wanted to pull some control back, the way DIYers have taken over loudspeaker design.  Ultimately, that took me to the driver manufacturers whose product costs far less than the IEMs being sold as a package.  With headphone drivers, the case for control is greater because the form factor is more forgiving.  The reason I think we can succeed is the sheer fact that the headphone manufacturers have settled upon Mylar as their material of choice and 40mm as the go-to size for serious listening (with some 50mm and 55mm exceptions).

 

Originally Posted by EddieE View Post

If the magnet is the next thing to play with bilavideo, how about investigating a donut magnet and magnet plate like the HD800/T1 have - would surely be a big advancement when it came to dealing with backwave?

 

By the way, I know I've said this to you before on this thread, but keep doing what you're doing, this is thread is in my top five all time, all forum threads. Great to read one man's quest to squeeze every bit of life out of a simple headphone design.


Ring magnets would work.  $3 or $4 is a premium, when it comes to magnets of this size, but I'd toss in a fiver or two if it gave me better sound.

 

Originally Posted by BobSaysHi View Post

Hey Bilavideo, the "cage" for the magnets has two holes already, but what would happen if you were to add another hole or two? I think that would be an easier experiment than replacing the driver magnet completely.


I know exactly what would happen.  I burned my fingers finding out.  My first attempts would look like this:

 

Photo on 2010-12-20 at 19.20 #4.jpg

 

Originally Posted by EddieE View Post

More holes would be interesting. One thing I'll say is that covering those holes makes no audible difference to the sound, but adding more just might...


The holes are for heat release.  They're an imitation of something seen on loudspeaker designs.  But to the extent that the magnet, itself, is a barrier to venting resonance, it would be interesting to see what more holes might do.

post #522 of 5003
Quote:
Originally Posted by BobSaysHi View Post


Hey Bilavideo, the "cage" for the magnets has two holes already, but what would happen if you were to add another hole or two? I think that would be an easier experiment than replacing the driver magnet completely.




 


I have a set of transducers pulled from a pair of boss over ear that have 4 holes. Don't know what to do with them though.
post #523 of 5003

Armaegis,

 

Any perceived loudness increase heard at the back of the cup as opposed to the front would most likely be due to the megaphone effect and not necessarily diaphragm profile. Again, when yelling at someone, it's more efficient to have ones cupped hands closer to the mouth than farther away. In other words, more db's are transmitted with closer cup walls. And still even more db's are transmitted with closer AND longer cup walls. The front of the Grado grill area doesn't have as pronounced a megaphone as the back of the Grado so the front wave should sound less loud.  

 

Oh, and I wouldn't recommend adding another magnet to the back plate for damping or otherwise. If the magnetic force of this additional magnet were to pass even somewhat through the Mumetal back plate (I think it's Mumetal) it would shift the stock magnet's center of field closer to the back plate. That would cause the voice coil to be in closer proximity to the plate due to the shifted magnetic field and the voice coil end might slam into the plate during high excursions. The diaphragm/suspension would also be stretched rearward beyond normal.

 

No, the only way one should try to increase the efficiency of the electromagnetic engine with additional magnets, if that's the goal, is to increase the magnetic field strength on the same PLANE as the stock magnet. I'd think drilling a couple of holes in the side walls of the mumetal plate cup on the same plane as the stock magnet and placing another circular magnet around the outside also on this same plane should do the trick. Or of course, one could always use a magnet stronger than stock to increase the electromagnetic efficiency...I wonder if they exist?

post #524 of 5003
Thread Starter 

 

Originally Posted by VinylCat62 View Post

Oh, and I wouldn't recommend adding another magnet to the back plate for damping or otherwise. If the magnetic force of this additional magnet were to pass even somewhat through the Mumetal back plate (I think it's Mumetal) it would shift the stock magnet's center of field closer to the back plate. That would cause the voice coil to be in closer proximity to the plate due to the shifted magnetic field and the voice coil end might slam into the plate during high excursions. The diaphragm/suspension would also be stretched rearward beyond normal.


Before reading this, I tried it on a whim.  It didn't have any effect I could hear.

post #525 of 5003
Quote:
Originally Posted by Bilavideo View Post

 

Originally Posted by VinylCat62 View Post

Oh, and I wouldn't recommend adding another magnet to the back plate for damping or otherwise. If the magnetic force of this additional magnet were to pass even somewhat through the Mumetal back plate (I think it's Mumetal) it would shift the stock magnet's center of field closer to the back plate. That would cause the voice coil to be in closer proximity to the plate due to the shifted magnetic field and the voice coil end might slam into the plate during high excursions. The diaphragm/suspension would also be stretched rearward beyond normal.


Before reading this, I tried it on a whim.  It didn't have any effect I could hear.


Ah...I see...OK. Guess that shield is doing a better job than I thought it could. Or the external magnet you tried wasn't of sufficient strength. Or it still wasn't in close enough proximity to the voice coil. Or both, or ???. I wonder what would happen if you added a couple more magnets to the back plate, one on top the other?

 

Or perhaps I'm all wrong on this. Do you know if that external magnet sticks to the rear backside of the plate even without the stock magnet in place? I mean is the plate all by itself magnetic even on the rear backside?

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