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Home-Made IEMs - Page 205

post #3061 of 5611
Quote:
Originally Posted by Furco View Post

Yes, I actually am using two vented drivers.  I've got a RAB + GQ configuration.  The RAB has a pinhole covered by a cloth disk and the GQ has, I believe a WBFK sitting on top of an ED.  I'm going to glue the GQ to the bottom of the shell to make sure there is good clearance for the WBFK vent.  As for the RAB, it looks like there's plenty of space above it.  I have a sneaky suspicion I crowded that GQ vent when I glued on the faceplate.

It can't be the WBFK vent causing a lack of base. That is your tweeter and it is connected to a crossover so it won't be giving any base at all.

I assume that you are using RAB as your base driver for this build.

2 possible explanations, either the RAB vent is getting blocked as others have noted, or the acoustic tube is getting bent when you put the face plate on causing a blockage in the tube.
Edited by CMOS1138 - 1/13/15 at 10:39am
post #3062 of 5611
Quote:
Originally Posted by Furco View Post
 

Yes, I actually am using two vented drivers.  I've got a RAB + GQ configuration.  The RAB has a pinhole covered by a cloth disk and the GQ has, I believe a WBFK sitting on top of an ED.  I'm going to glue the GQ to the bottom of the shell to make sure there is good clearance for the WBFK vent.  As for the RAB, it looks like there's plenty of space above it.  I have a sneaky suspicion I crowded that GQ vent when I glued on the faceplate.

 

I'm not sure I'm following everyone's logic about the possibility of the tubes not having a good seal.  Wouldn't I see a bad frequency response with and without the faceplate on if that was the case?

Personally I don't sit well with the tube sealing being at fault either. It sounds more like you somehow covered the vents while gluing the faceplate.

 

You can test this by actually covering the vents and check if the response is the same as when you have the faceplate on.

post #3063 of 5611

The seal between the tubing and the nozzle might be leaking. 

post #3064 of 5611
Sorry for what are probably noob questions but I'm trying to make a simple one-driver to try out.

I have a decent understanding of molding and creating a shell.

I have an idea of what driver I should use and I know I'm supposed to attach an acoustic tube to it and put a filter in it. That's simple enough, can someone explain (with pictures preferably) how to do the rest and what materials I might need? The cable part has me lost. Most people are going with multiple drivers so I'm a little confused as to what I need.

Unless there's already a very thorough guide/tutorial I haven't perused, then it'd be nice if you lead me there.
post #3065 of 5611

There is a very detailed guide here written by one of members here. You will have to search it in this thread.

post #3066 of 5611
Quote:
Originally Posted by Breezy View Post

Sorry for what are probably noob questions but I'm trying to make a simple one-driver to try out.

I have a decent understanding of molding and creating a shell.

I have an idea of what driver I should use and I know I'm supposed to attach an acoustic tube to it and put a filter in it. That's simple enough, can someone explain (with pictures preferably) how to do the rest and what materials I might need? The cable part has me lost. Most people are going with multiple drivers so I'm a little confused as to what I need.

Unless there's already a very thorough guide/tutorial I haven't perused, then it'd be nice if you lead me there.

You can find the DIY guide in my signature. Well, it's one of the diy guides. It includes links to the DIY Cable forums here at Head-Fi as well.
Edited by Furco - 1/14/15 at 8:19am
post #3067 of 5611
Quote:
Originally Posted by Xymordos View Post

The seal between the tubing and the nozzle might be leaking. 

GIVE THE MAN A CIGAR!!!

That is exactly the issue I'm having. Evidently the noise inside the shell that is leaking through the nozzle is causing my lower frequencies to cancel out.

I took these damn things apart so many times trying to solve this problem, it's ridiculous. This is definitely one to burn in the memory banks to check for on future builds.

Thank you all for your suggestions. I heeded everyone trying to solve this problem. Once I firgure out how to plug up the leaks, I'll post the before/after pics.
post #3068 of 5611

:confused_face:

 

 

Well, glad you got it sorted...

post #3069 of 5611

Haha, glad you fixed it. The same thing happened to me before when I didn't seal the nozzle properly.

post #3070 of 5611

So for those of you interested, here's what the frequency response looked like after I sealed up my IEMs:

 

 

 

A little explanation of the graph:

*  The Green line was what I was expecting to see with an unfiltered RAB+GQ config.

*  The Red is what I actually saw.  WTF - indeed!!!  Major drop in dB from 100 - 400Hz and a crazy shift of the lower mid-range.  Notice that the upper frequencies are more-or-less, unaffected.

*  The Yellow line is what it looked like after I plugged up the leaky nozzle trying to diagnose the problem.  That looks MUCH better!!

*  Teal and Violet are the Right and Left IEMs after adding the acoustic filters. 

 

Now some pics:

 

Here's a view of the two gaps, basically, a large one at 10 o'clock and another small one at 4 o'clock.

 

 

A little bit better view of those gaps.

 

I stuffed them with some dense foam and retested the frequency response.

 

 

After validating that those gaps were what was causing me such hell, I had to seal them up.  For one of the IEMs I was able to stuff some extruded silicon into the acoustic tubes.  This was idea as nothing sticks to silicon so they'd be easy to remove after covering the nozzle with UV resin and curing.

 

 

 

For the other IEM, I couldn't get the silicon into the nozzles, so I resorted to some other flexible tubing I had around. There's more than one way to skin this cat.

 

 

Both worked really well to seal up those leaks.  Here the fixed nozzle.

 

 

 

And the finished product complete with a custom made cable:

 

 

Thanks again for everyone's input.  It was a team effort!!!

post #3071 of 5611

cool! I'm not sure what your measuring equipment is, but frequency response looks pretty decent and it is probably around something I would foresee as an outcome from RAB GQ combo. I'd also suggest adding some smoothing 1/12octave is good, and also use sine sweep instead of noise. It should improve the look of the graph. I'm also not sure how accurately is calibrated your equipment but 50db level is quite low, and if you do actual measurement at that level you are getting a lot of noise from hardware, try doing graphs at around 90 or 100db.

 

And yes, you have to seal tubings from the inside of the monitor!


Edited by piotrus-g - 1/14/15 at 2:27pm
post #3072 of 5611
I found a place to do awesome art work for faceplates and it very cheap. The nail saloon my daughter goes to will do any air rushing or all by hand with acrylic nail paint then i will seal them with dreve. I will have to post pictures when get them done. The acrylic they use is also uv.
post #3073 of 5611
Wondering what you guys think would be a good DIY IEM filter. I have a pair of T-Peos H-300 and they're a tad bright at times, mostly over long sessions they become fatiguing, knocking some of the highs would help too. What could I use to place over the nozzle and calm them a little? Any thoughts?
post #3074 of 5611
Quote:
Originally Posted by H20Fidelity View Post

Wondering what you guys think would be a good DIY IEM filter. I have a pair of T-Peos H-300 and they're a tad bright at times, mostly over long sessions they become fatiguing, knocking some of the highs would help too. What could I use to place over the nozzle and calm them a little? Any thoughts?

Wool is a good material to ball up and put into the tubes. I also had a lot of luck using various foam I saved from getting packages in the mail.



Here some testing I did with various materials. It shows how the FR behaved with various types i had on hand.



The red line is the Reference (no-filter) so you can see some of the foams were very good, in my opinion, at shaping the higher frequencies.
Edited by Furco - 1/17/15 at 3:32pm
post #3075 of 5611
Quote:
Originally Posted by piotrus-g View Post
 

cool! I'm not sure what your measuring equipment is, but frequency response looks pretty decent and it is probably around something I would foresee as an outcome from RAB GQ combo. I'd also suggest adding some smoothing 1/12octave is good, and also use sine sweep instead of noise. It should improve the look of the graph. I'm also not sure how accurately is calibrated your equipment but 50db level is quite low, and if you do actual measurement at that level you are getting a lot of noise from hardware, try doing graphs at around 90 or 100db.

 

And yes, you have to seal tubings from the inside of the monitor!

 

Agreed, 50dB is very low, too low to get something meaningful in terms of a FR chart.  I can definitely say that the numbers on the  y-axis are more of a reference than anything.  I'm doing my FR testing at around 85dB, for sure.

 

For my Freq.Response Test Rig, here's my setup.  It's a little complicated but I didn't need to buy anything as I had all this stuff in-house from previous projects:

Interface: PreSonus AudioBox 2x2 USB (http://www.presonus.com/products/AudioBox-USB

Mic:  Electro-Voice Cardinal Condenser mic (http://www.electrovoice.com/product.php?id=89)

Workstation: MacBook Pro  (OSX 10.9)  (http://apple.com)

Software:  Electroacoustics Toolbox v3.5.2 (http://www.faberacoustical.com/products/electroacoustics_toolbox/)

Test Tones:  I got all my test tones and pink and white noise, sine sweep sound clips from http://www.audiocheck.net/soundtestsaudiotesttones_index.php

 

Here's a look at the mic setup.  It definitely doesn't looks like a Cardinal Condenser mic at all; more like a pipe bomb.  Anyway, the import thing here is that I've tried to isolate the mic as best as I could see fit.  I put it on a large block of lightweight foam to reduce low frequencies resonating when the mic is in contact with hard surfaces.

 

 

The white disc with the hole are made from silicon and are interchangeable in the rig.  I've got a few discs I made based on the diameter of the tubes i'm trying to test.

 

 

I've isolated the back of the pipe with a layer of medium foam.  There's about 2 inches of air between the foam and the back of the mic to further improve the isolation.

 

If I take the silicon disc off the front of the rig, you can see that there is a 20mm hole to the mic. Why 20mm?  I wish I had some scientific explanation for it, but I don't.  It just so happens that this large dense black foam had a 20mm smoothed hole already in it, so I used it as-is. 

 

Taking the foam block out of the front of the rig, you can see the entire grill of the mic and also get a sense for how thick the foam actually is (about 29mm or 1.5 inches).

 

 This mic fit perfectly inside the grey PVC tubing.

 

 

Sealed up with some electrical tape.

 

And here's one way I position an IEM for testing.  It works surprisingly  well.

 

If people are interested, I'll describe how I use Electroacoustic Toolbox to do FR testing.  I did give ARTA a shot but need to get some more experience with it. It doesn't seem to allow me to do sine sweeps.

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