Diy AMT

[bsyoon]

Thank you so much Solhaga,
I have still some feeling left for U-shaped pole piece.
We didn't compare two models under the same conditions.
Anyway, I always feel thanks for you and båndsei.
I've made AMT diaphragms in the manner of silkscreen print but was wondering which magnet system is better. The sequence is reversed with your case.
Good luck !

 

[solhaga]

båndsei, I managed to get some "Frokostfolie" by Vita/KM Plast.

The paper is more "oily" (fedttaet) and I find it more easy to cut.
But then the paper isn´t that easy to peel of I guess.

So I wondered, why remove the paper at all? It shouldn´t add that much weight and you would get the insulatition for free. Any opinion?

 

[solhaga]

"Any opinion?"

Sorry, the folds will be too stiff!

 

[båndsei]

This one?
It is 10my.
You can leave it on,you cut paper and alu in the folds.
I have not used the Vita alu/paper,but earlier types had to be seperated with heat,hairdryer or heatgun.
I have made Amt´s and Ribbons with the paper on.
I remowe it to save weight.

Bernt

 

[solhaga]

Yes, that´s the one.
I´ll see what´s the weight for the finished membrane.
Thanks for your advice.

BTW, it is easy the peel off the paper with your fingers only.

 

[båndsei]

I am working on my "curved" Amt.

It sounds good.Better dispersion,more linear.

I have to make a "horn" like my latest model.

Bernt

 

[båndsei]

Here my 2 babyes:

Have to make some tests incl A-B tests.

Bernt

 

[solhaga]

It would be interesting to know about your listening impressions for the two setups.

I have something similar in mind, but with concave configuration instead of a convex like yours.
Focus is then some 30 cm behind the head in sweetspot and yes, it will be a small sweetspot but I don´t jump around when I´m listening.

 

[tinitus]

now you really make me smile

 

[solhaga]

I had a painful experience with my line arrays where I tried to solve problems that wasn´t there. The problem went away when I realized that I sit alone and still when I listen to music. So why solve the problems with vertical dispersion and CTC?

Of course if the aim is to have an omni-response båndsei is going up the right alley.

 

[båndsei]

Solhaga ,you are right about my aim.
I use my stereo/surround in a living room and dont want sweet spot there.In my workshop
I can use sweetspot settings.I still have a pair of magnetostats in my workshop.
I think if you make the speaker too direktiv you get higher level above midrange.
It might sound impressive,but not linear.

Bernt

 

[solhaga]

you get higher level above midrange

Yes, that´s why I EQ that part if need arises.

How do you measure the dispersion, moving the microphone or just listening?

 

[ondesx]

To Bernt...

Hello Bernt,

Perhaps this is another easier and probably lighter way to design an AMT diaphragm... These guys are using Graphene as conductors. This will be the thinner way to trace conductors whatever the design !

Here you have a few links to this method...

http://arxiv.org/pdf/1303.2391v1.pdf

Robert Murray-Smith - YouTube

https://www.smashwords.com/books/view/304668

My Best,

 

[ondesx]

To RayCtech

Hi Dude,

Any chance this time to see one of your Wide Range Heils ?

If they aren't produced yet by a company why don't share your skills with us ?

My Very Best,

 

[båndsei]

Here an other model:

It is angeled 10'

Dispertion is right for me.Sound too.I am crossing at 1000hz. 48 db.Might try lower.
These ones I am going to keep for a while.

Measurements later.

Bernt

 

[RayCtech]

Hi Dude,

Any chance this time to see one of your Wide Range Heils ?

If they aren't produced yet by a company why don't share your skills with us ?

My Very Best,

My new music room are finished in a weeks time from now and then they can be both viewed and listened to..

 

[båndsei]

Measurements on axis at 1 meter 2.8v.:

Is it possibly to post REW files.

Bernt

 

[SEdwards]

Your work has come a long way - a real achievement! It's been a pleasure following this thread.

I've finally started on my diaphragm tests (yay!) using kapton. Still experimenting for the best way of cutting the Al without tears (both meanings of the word).

@Ray - are your diaphragms also made via manual cutting, or did you etch the traces?

Tomorrow I'm hoping to find some appropriate metal for a folding jig.

 

[båndsei]

What is the thicknes of the capton , and is it selfadhesive ?

Bernt

 

[SEdwards]

The tape that I have is 1 mil + glue, so about 2 mil total thickness, I believe. I bought it for 6 EUR from ebay for a roll of 50 mm tape. It was easier/cheaper for me to source than the 3m 74 tape and makes for good first experiments at the very least. Beyma and a few other brands are using kapton, I think. Also my Fostex headphones (planar) use kapton. The temperature resistance will be good, at the very least.

The glue dissolves without a problem. I have made some small diaphragms, but need to make the folding tool to give them a try. I will start at 50 mm and work my way up.

I will probably end up using oversized diaphragms with only the middle exposed, using the rest like a suspension to lower the resonant frequency and avoid boundary effects. Hopefully they will be suitable for the mouth of a Synergy horn, eventually.