DIY Air Motion Transformer

Status
Not open for further replies.
Jump to Latest
#22
I made some monopoles from spare AMT ribbons I had using simple ceramic magnets (25x50x100mm + smaller 5x10x30mm magnets). Sounds good but as good as Ravens. About effiency as orignals. Cost about Aust$200 for water cut grill slots + $50 magnets.
 
#24
Originally posted by promitheus
How far are you till now?
Have tested anything yet?
By the way where can I get some diaphragms for 60 Euro?
Click to expand...

I've taken some pictures of my disassembled AMT. I will add dimensions of the parts to them. I'll probably be able to post the pictures tomorrow.

I have not tested anything until now. I have yet to think of an efficient way to either cut the sheets or replicate the pole pieces as a block. Laser cutting is out (at least for me) due to cost reasons. As I said before, I want to get something to work as simple (and cheap) as possible. Experimentation and optimization will start after I get positive results.

I'm busy with other duties, so be prepared slow progress.

Replacement diaphragms can be bought at http://www.simplyspeakers.com/12diaphragms.htm for 64 US$ / piece wich translates to 53 Euros as of today. Us European DIYers should consider a group buy to save on shipping costs.

There have been rumors that the new diaphragms sound worse than the old ones. I couldn't hear any significant difference when comparing old and new AMTs, but the setup of my test wasn't ideal.
 
#26
I also own (and use) a pair of AMT-1 tweeters. Great sounding speakers, very dynamic, not as refined as a Raven but bigger and and more live sound.

I find the build quality rather poor. I think it would be easy to do this better your self. The plastic case, wich is mostly hollow, resonates with loud music. I have not opened them yet, so I'm curious about the pictures. Maybe it's easy to fill the hollow space with sand or something or replace the side panels with wood or aluminium for example. Any ideas ?
 
#27
Standby for the pictures.

Yes, the build quality of the first AMT 1 is indeed poor. Taking a look inside only confirms this impression. Things improved with the later series - the case material is now rubber. Still, this old 70's driver sounds better than all dome tweeters I came across, even the newer ones which are some 30 years of experience ahead.

If people had recognized the potential of the AMT principle and invested more time and money improving it, where would we be now? There are lots of things to try...
 
#29
By the way these are my speakers.
 

Attachments

  • stereo.jpg
    stereo.jpg
    37.2 KB · Views: 794
#30
AMT-freak, how did you open up the AMT's. The sides are all glued together, so I think the only way to do it is to saw them off carefully. I would like to get rid off these curved sides and replace them with straigt rectangular ones so it will be easier to mount them trough a hole in my open baffles.
 
#33
The sidewall... You can definitely do better in terms of dampening and preventing resonances.

@Sjef: As you can see in the above post, the magnet assembly sticks out the sides some millimeters, so you cannot simply attach a straight panel. I removed the sidewalls with a sharp knife.
 

Attachments

  • sidewall.jpg
    sidewall.jpg
    21.7 KB · Views: 814
#38
The most important parts, the magnets: Sized 127mm x 19mm x 50mm. BTW, they do look that bad in an original AMT straight from the factory. Otherwise I would have found all the missing pieces in the case.
 

Attachments

  • magnet.jpg
    magnet.jpg
    17 KB · Views: 622
#40
@Promitheus: They are magnetized through the thickness.

Here's the pole pieces. There are four identical stacks in each driver. They are made of 1.5mm steel sheets, height of the stack is about 120mm, they are 9.5mm long and 69mm wide.
 

Attachments

  • pole-pieces.jpg
    pole-pieces.jpg
    20.9 KB · Views: 727
Status
Not open for further replies.
Top Bottom