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Just listened to some Fostex T50RPs today... WOW! - Page 693

post #10381 of 10570
Quote:
Originally Posted by siles1991 View Post

guys any ideas on how to cleanly solder wires onto the drivers without leaving too much of a mess? I don't want to use the jacks because they tend to get loose easily.

Get some SPC 19-strand 28 or 30 AWG wire from ebay seller:  navships  This wire takes solder like a sponge, unlike the factory wire of the stock drivers.

Strip off insulation to expose a little more wire than needed and pre-tin.

Lay wire across solder pad.

Use tiny strips of tape to hold wire in contact with the solder pad, on both sides of the solder pad.

Add a little bit of flux with a toothpick to the wire/solder pad.

500 to 550 degrees F.

Pre-tin solder iron tip.

In and out in 1 to 2 seconds.

Snip off the excess wire on the other side of the solder tab.

post #10382 of 10570
Quote:
Originally Posted by Nevod View Post

I suspect the 10-11 kHz peak is due to driver's dimensions, not the cup..

 

Quote:
Originally Posted by a_recording View Post

 

I rather suspect that too. I can't imagine a square driver is the best in terms of producing a natural wavefront.

 

That's one possibility. The cup/baffle design is another possibility; or, it could be an interaction effect. Is there any research on this? If not, experimentation is the only way I know to find out. I wonder if any engineers have modeling software that could answer this question?

 

The drivers can't be altered. Changing the dimensions and/or shape of the cups and baffles may result in different FR....maybe better...maybe worse. 

post #10383 of 10570

Actually, I was just thinking upon looking at the driver of the T50RP:

 

The high frequency ringing could be a product of the way the driver is mounted. The actual moving element of the driver is held in place behind a plastic grid, and thus will always be several mm away from being 'flush' with the baffle.

 

As I understand from designing speakers, not flush mounting a tweeter is generally a bad idea because it will produce interactions between the edges of the baffle and the sound waves - leading to dips and roughness to the treble.

 

According to my speaker design handbook, they generally stopped using wave plates / phase discs in front of tweeters because they can produce cavity resonances and a 'tizziness' to the sound.

 

This effect is probably even worse on the T50RP driver considering the giant grid in front of the driver introduces many many edges.

 

Some interesting measurements taken in this post on the effect of surface mounting a tweeter:

 

http://www.rjbaudio.com/Audiofiles/flush%20mounting.html


Edited by a_recording - 9/3/13 at 5:51am
post #10384 of 10570

I've been told that generally if something doesn't have an immediately apparent explanation and might require some investigation, it's usually aliens.

 

How close to flush mounting could you realistically get with the T50RP driver?

post #10385 of 10570

I actually just took apart the T50RP to answer this question. This is a really cool pic of the results:

 

 

Now I better understand how the T50RP driver works. It is a voice coil printed on a thin film sandwhiched between two passive magnet assemblies. 

 

The magnets are incredibly strong. It's now obvious to me why they are so heavy and require 9 screws and 4 retaining clips to keep the whole assembly together. The magnets repel each other with an insane amount of force, actually enough that when I unscrewed the screws and tried to get the driver past the retaining clips, the magnets snapped the clips on one side of the driver off. That's okay, this was a spare driver with the white felt on the rear removed, but I do not advise anyone try this. (Thank goodness I wear glasses).

 

I think this also answers my question about flush mounting: I believe the plastic grid is there to retain the magnets and prevent the whole plate from bending from the magentic force. In other words, I think it is an integral part of the design and I do not think much could be done about it.

post #10386 of 10570

On another note, I should add that the T50RP seems very sensitive to positioning on the ear, and you can reduce or increase the ringing just by moving it backwards and forwards on the head as Rin Choi has also observed.

 

This may be because both the plastic grid and the driver shape (square) causes lobing effects that mean sound does not radiate from the driver in a uniform sphere but instead some other shape. 

 

(If you can imagine, sound should radiate from a perfect dome driver in a spherical shape, but if you were to put a grid in front of it it will radiate unevenly in little mini-squares like if you pushed playdough against a grid of squares)

 

This effect would be more severe at high frequencies since low frequencies tend to bend around obstacles.


Edited by a_recording - 9/3/13 at 6:01am
post #10387 of 10570

Also, I don't want to toot my own too much, but I have been listening to my set of T50RP's with my 3D printed baffles over the last few days and comparing with a stock T50RP with Shure 840 earpads. I quite like the sound. They still have the slight boxiness of the stock T50RP sound but mid-bass is cleaner and everything sounds more balanced. I think this would be a good, consistent base for further modification.

 

I've sent a copy of the part off to bluemonkeyflyer for measurements to determine just how different this part is compared to simply blocking the baffle port on the stock baffle.

post #10388 of 10570
Quote:
Originally Posted by bluemonkeyflyer View Post

Get some SPC 19-strand 28 or 30 AWG wire from ebay seller:  navships  This wire takes solder like a sponge, unlike the factory wire of the stock drivers.

Strip off insulation to expose a little more wire than needed and pre-tin.

Lay wire across solder pad.

Use tiny strips of tape to hold wire in contact with the solder pad, on both sides of the solder pad.

Add a little bit of flux with a toothpick to the wire/solder pad.

500 to 550 degrees F.

Pre-tin solder iron tip.

In and out in 1 to 2 seconds.

Snip off the excess wire on the other side of the solder tab.

actually was asking about cable entry into the cups not the soldering part...make it nice and clean entry

post #10389 of 10570

I believe some people have "widened" the holes on those metal plates, IIRC, to one long, thin opening. Or maybe sections...

 

Sounds like more trouble that it's worth to me, but I wouldn't really know.

post #10390 of 10570

I would need to drill new holes for the cable entry, so I have to seal my old holes. From reading around would GE Silicone II work? I'm planning to reseal, repaint and re-drill holes in the future.

 

edit: i cant find ge silicone ii in my country so i need to find alternatives if possible.


Edited by siles1991 - 9/3/13 at 10:32am
post #10391 of 10570
Quote:
Originally Posted by siles1991 View Post

actually was asking about cable entry into the cups not the soldering part...make it nice and clean entry
Basically you want to hardwire your cables to drivers.
And you are wondering what to use to seal off the leftover hole around a new hole you're making.

My guess is most people did not understand your question well lol.
Anyhow I know little about names of parts and tools and etc. but silicone caulk could work. Ideally you should still find a method as cable strain relief though. Either based on that or over that you put something else as seal.
post #10392 of 10570
Quote:
Originally Posted by kalbee View Post


Basically you want to hardwire your cables to drivers.
And you are wondering what to use to seal off the leftover hole around a new hole you're making.

My guess is most people did not understand your question well lol.
Anyhow I know little about names of parts and tools and etc. but silicone caulk could work. Ideally you should still find a method as cable strain relief though. Either based on that or over that you put something else as seal.

mhmm exactly what I meant! will check out silicone caulk hopefully my local hardware store sells em cheap.

post #10393 of 10570

Grommets are another option. They look cleaner than silicone will, I'd bet.

post #10394 of 10570

 

 

 

 

 

 

This is what I got so far today.It is made out of pine wood. I don't want the circular design so I hand carved it to my desired curve.

Bass is prominent than that of the modified stock cups. 

post #10395 of 10570

 

 

 

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