[Torac]

Something else comes to mind too. With your single sided design, what side are you measuring the distortion from?

Is it the magnet side or the non magnet side? If you are measuring from the magnet side, maybe you are seeing some distortion from reflections off the magnets?

I measure from the non-magnet side since it's the side that faces the ear. Perhaps there are also backwave reflections off of the magnets that still cause some distortion.

 

[xxGilgaxx]

The FR graph seems too flat, what is the microphone you use ? I use a MiniDSP Ears. Anything that is open like the MiniDSP umik 1 will not pick up low-ends and Highs

 

[Torac]

The FR graph seems too flat, what is the microphone you use ? I use a MiniDSP Ears. Anything that is open like the MiniDSP umik 1 will not pick up low-ends and Highs

I use the umik-1 coupled to a flat piece of cardboard, I have a piece of leather on the side the driver is being measured on and I use bluetack to get a seal around the hole in the cardboard for the mic. Ideally I would also have a foam block behind the cardboard but this seems to work for now. In the future I intend to get an EARS.

 

[xxGilgaxx]

MiniDSP Ears will have a much flatter bass and more spikes in the highs

 

[Torac]

Quick update on my planar driver. I have found a method which allows me to make my own material out of any film and aluminium foil I choose within reason and etch it successfully. This has allowed me to make diaphragms using mylar as thin as 1 micron. I am now using a 3 micron material similar to mylar but with much nicer properties such as double the elasticity, this is combined with 6 micron aluminium for my trace. Here are some measurements I took of a driver I assembled using this material (I won't be disclosing this material for obvious reasons):

Frequency response:

Distortion:

I don't trust the bass measurements on this mic, especially below 20hz, as results vary quite a bit between measurements but as you can see midrange distortion is very good compared to my previous attempts, on average it's around 0.2%. This is all without any damping material behind the driver.

 

[Tjj226 Angel]

Does the etching process still rely on the solid ink printer? I have kept my eye out for one for a while, but they are quite expensive and unruly.

I started to look into graphene ink and seeing if I couldn't simply print the circuit directly on the mylar.

Im also curious about this new non mylar based material. I would tend to think that higher elasticity is a bad thing. In a perfect world the planar diaphragm would actually be a perfectly rigid plate with close to 0 mass and that can somehow move in a purely pistonic fashion.

I would tend to think that a material that has higher elasticity will act less like a plate and you would end up with more second order harmonics. That being said, the more densely packed you can make your coil traces, the more even and uniform the magnetic force will be over the entirety of the plastic which means your distortion will go way down.

 

[Torac]

Does the etching process still rely on the solid ink printer? I have kept my eye out for one for a while, but they are quite expensive and unruly.

I started to look into graphene ink and seeing if I couldn't simply print the circuit directly on the mylar.

Im also curious about this new non mylar based material. I would tend to think that higher elasticity is a bad thing. In a perfect world the planar diaphragm would actually be a perfectly rigid plate with close to 0 mass and that can somehow move in a purely pistonic fashion.

I would tend to think that a material that has higher elasticity will act less like a plate and you would end up with more second order harmonics. That being said, the more densely packed you can make your coil traces, the more even and uniform the magnetic force will be over the entirety of the plastic which means your distortion will go way down.

This method used vinyl as the mask when etching, it takes more time to apply and remove but if you don't wish to get a solid ink printer this could be a good solution for you. I have a silhouette portrait which I use to cut the vinyl but you could get someone else to cut the masks for you if you want to try it first. The only downside is that with my silhouette the thinnest I have been able to go is 0.75mm wide for each trace line but I have had others with more professional plotter cutters go down to 0.5mm.

Pistonic motion is good but if you think about it, if the material is really rigid at the edges/perimeter then the diaphragm won't move very far as a whole, a bit like a dynamic driver cone but with a really rigid surround. Having a material that is more elastic means you can tension it nice and high to keep it flat and pistonic but still get good bass with lower distortion, at least this is what I have found so far.

I found that the 8 micron material I was using was too rigid and it was really hard to get any bass without lowering the tension which made it measure worse in other respects, I imagine the only way to use thicker material like this would be to have a very large surface area allowing it to play deeper without moving quite as much.

 

[setmenu]

I only logged in by chance and found this thread and Wow what great project/s top work!
I had a dabble with this sort of thing a while back,here is a link to another thread with a post from me about it.
My ribbon transducer
I have yet to plough through all the details here, but feel it is going to light that fire again if not careful
keep up the good work

 

[Torac]

I only logged in by chance and found this thread and Wow what great project/s top work!
I had a dabble with this sort of thing a while back,here is a link to another thread with a post from me about it.
My ribbon transducer
I have yet to plough through all the details here, but feel it is going to light that fire again if not careful
keep up the good work

Thanks, I'm glad you like my project so far

I'll have a read of your post as it looks interesting!