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Fostex T50RP Incremental Mods and Measurements - Page 47

post #691 of 1109
Quote:
Originally Posted by jasonb View Post

I've asked this before, and I guess I have to ask it again, does anybody know of anyway to tune these so there in less output in the 250-500hz range? Mine still sound a bit honky and sound a lot better when I EQ out 3db at both 250 and 500hz. I'd rather not have to resort to EQ, any ideas?

It's possible that the foam makes a big difference in that area (if you are still using only adhesive felt inside).

post #692 of 1109

Maybe. 

Quote:
Originally Posted by Thujone View Post

It's possible that the foam makes a big difference in that area (if you are still using only adhesive felt inside).

post #693 of 1109

My DIY album. Lots of indepth pictures, instructions in the comment on the pics. Nothing groundbreaking, but might clear up some of the general build steps. Feel free to use these in OP or anywhere else. 

 

http://imgur.com/a/bBXrc

post #694 of 1109
Quote:
Originally Posted by mvrk10256 View Post

My DIY album. Lots of indepth pictures, instructions in the comment on the pics. Nothing groundbreaking, but might clear up some of the general build steps. Feel free to use these in OP or anywhere else. 

 

http://imgur.com/a/bBXrc

It looks like you might have used adhesive backed felt instead of stiff felt. Dangerous for your drivers and cannot sound too good. I do not recommend that at all!

 

Apologies if I am wrong.

post #695 of 1109
Thread Starter 
Quote:
Originally Posted by chrislangley4253 View Post

It looks like you might have used adhesive backed felt instead of stiff felt. Dangerous for your drivers and cannot sound too good. I do not recommend that at all!

 

Apologies if I am wrong.

 

I missed that detail. The felt does appear to be the self-adhesive type. I agree that adhesives may foul the drivers' stock white damping material. I had this happen after multiple applications and removal of Transpore tape applied directly to the rear of the drivers.

 

Using self-adhesive felt runs the risk of over-damping = too little bass: too much treble, depending on the rest of the configuration, of course. 

 

The holes punched in the felt may work, by partially"venting" the drivers, so that the drivers are not completely "choked off"... as long as the holes are centered over the grid spaces and not over the grid partitions. 

 

My 2 cents

post #696 of 1109
Quote:
Originally Posted by chrislangley4253 View Post

It looks like you might have used adhesive backed felt instead of stiff felt. Dangerous for your drivers and cannot sound too good. I do not recommend that at all!

 

Apologies if I am wrong.

 

I did in the original build. It made the headphones very clear, and very treble focused. It was a weird sound. I have since gone back and used a proper hole punch and non adhesive stiff felt w/ 6 holes to cover the drivers. The bass is back, and the headphones sound a lot better. I have fixed the album to reflect this. 

 

Quote:
Originally Posted by bluemonkeyflyer View Post

 

I missed that detail. The felt does appear to be the self-adhesive type. I agree that adhesives may foul the drivers' stock white damping material. I had this happen after multiple applications and removal of Transpore tape applied directly to the rear of the drivers.

 

Using self-adhesive felt runs the risk of over-damping = too little bass: too much treble, depending on the rest of the configuration, of course. 

 

The holes punched in the felt may work, by partially"venting" the drivers, so that the drivers are not completely "choked off"... as long as the holes are centered over the grid spaces and not over the grid partitions. 

 

My 2 cents

Correct. I only had it on there for about 24 hours and it pulled off without any issue or any residue. I have since fixed the issue. 

post #697 of 1109

Hi, BMF. I'm going to make a measurement rig like yours but i'm still vague about the measure process, can you explain more?

post #698 of 1109
Thread Starter 
Quote:
Originally Posted by proid View Post
 

Hi, BMF. I'm going to make a measurement rig like yours but i'm still vague about the measure process, can you explain more?

Hi proid,

 

Go to the beginning of Post #1.  :-)

 

I recommend solderdude's phantom power supply design with a link to his site.

 

Take a look at the newest version of REW and compare to ARTA and FuzzMeasure.

 

WM-61A mic capsules are hard to find but some may still be available on ebay from a German seller...that's where I got my last batch. If you cannot find any, let me know.

post #699 of 1109
Quote:
Originally Posted by bluemonkeyflyer View Post
 

Hi proid,

 

Go to the beginning of Post #1.  :-)

 

I recommend solderdude's phantom power supply design with a link to his site.

 

Take a look at the newest version of REW and compare to ARTA and FuzzMeasure.

 

WM-61A mic capsules are hard to find but some may still be available on ebay from a German seller...that's where I got my last batch. If you cannot find any, let me know.

 

Can i use other tips than etymotic? I'm afraid i can't find it here.

post #700 of 1109
Thread Starter 
Quote:
Originally Posted by proid View Post

Can i use other tips than etymotic? I'm afraid i can't find it here.

Sure. You'll be comparing to your specific measurements and any known reference headphone you measure with your kit. I think triflange work better than foam tips, though.

I can send you some Etymotic tips.
post #701 of 1109
Quote:
Originally Posted by bluemonkeyflyer View Post


Sure. You'll be comparing to your specific measurements and any known reference headphone you measure with your kit. I think triflange work better than foam tips, though.

I can send you some Etymotic tips.

What would you recommend to seal pre-made holes, so i can drill new holes for new cable entry.

post #702 of 1109
Quote:
Originally Posted by bluemonkeyflyer View Post


Sure. You'll be comparing to your specific measurements and any known reference headphone you measure with your kit. I think triflange work better than foam tips, though.

I can send you some Etymotic tips.

 

Thanks Keith, i think i will try some eaiser to find tip first. My concern is with this schematic, what will i connect to the TRS and RCA jack?

post #703 of 1109
Thread Starter 
Quote:
Originally Posted by proid View Post
 

 

Thanks Keith, i think i will try some eaiser to find tip first. My concern is with this schematic, what will i connect to the TRS and RCA jack?

Those are just examples for showing various connection options. You can use whatever type of connector you need. One is for the Mic IN (into the phantom power supply/aka pre-amp) and the other is Line OUT (from phantom power supply) to your PC or Mac Line IN/headphone IN.  Then wire your electret microphone capsules and terminate in the connector of your choice. I use RCA and 3.5 mm TRS plugs/jacks. You could omit the RCAs and connect the + and - wires from the mic directly to a 3.5 mm TRS plug. You must use a stereo plug even though you use only the Tip (Ground) and Ring (Hot).

 

If you read further in the discussion associated with the pix above, you will find similar questions I asked solderdude and his replies.

 

Here's a picture of mine. The mic IN jack is the one on the top next to the large cap. The Line OUT jack is nearest the smaller cap and the +/- (Red and Black) wires coming into the PCB at the bottom right.  Note: the Two single rows running long ways in the center of the PCB. All the common grounds from caps, resistors, and connecting wires share this "electrically linked" row.  I'll look for more pix and my diagrams, tonight.

 

Hope this helps.

 

 

 

post #704 of 1109

@BMF: Thanks, i'm totally understand now. So i can get some comply foam here: T500, T400, T200, which do you think i should go for?

post #705 of 1109

Hey guys, just before I fell asleep last night in bed, I had a weird thought:

 

Would it be possible to swap out the drivers from a T50RP and put them into another can?

 

If so, assuming the size of the enclosure was vastly different, it's bound to get a pretty different sound signature, right?

 

Any thoughts on this?

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