[MoAv]

I've taken my TF10 to a hearing solutions facility in my local city, specializing in customizing hearing aids for patients.
They had great knowledge about fitting audio instruments into small spaces and they took the opportunity to try and make my customs. After a couple of weeks of work they were done, I've tried them on and although they felt like having a good isolation, they lack bass and some frequencies were quite painfull, they're almost no soundstage, and the overall sound was degraded dramatically.
Bottom line, I need a place that can analyze the spectrum for abnormal behavior in sound, and make the adjustments needed.
 

 

[FullCircle]

Any time you change an acoustic chamber in shape, size etc you will have a change in acoustic properties....  This is the nature of sound.
 
In short, there is no way you will get the "exact" sound from your customed shelled IEMs that you obtained from you TF10 while the parts where still housed in the original housing.
 
Further more, even if a company did have a freq. analyzer, that company would have to be VERY familiar with the TF10 in order to distinguish between a "correct" pattern, versus a non-correct pattern.
 
For what it is worth, if I had to guess...  I'd say they took your filters out and did not replace them...   but that is just a guess & I say this because I knew a guy in the hearing aid industry that was re-molding non-customs to custom products.   He was a technician that had no clue regarding acoustics etc etc.
 
He had a cup full of dampers/filters...  that he had collected over a period of time... and he had no idea he what the were and thought they were needless so he just collecte them rather than place them in the coresponding tubing.
 
Just because you know how to make a hearing aid shell, does not mean you know how to make a CIEM. (but it is a good starting point)
 
Good luck to you.
 
Wizard
 
 
 

 

[goodvibes]

Quote:

Any time you change an acoustic chamber in shape, size etc you will have a change in acoustic properties....  This is the nature of sound.
 
In short, there is no way you will get the "exact" sound from your customed shelled IEMs that you obtained from you TF10 while the parts where still housed in the original housing.
 
Further more, even if a company did have a freq. analyzer, that company would have to be VERY familiar with the TF10 in order to distinguish between a "correct" pattern, versus a non-correct pattern.
 
For what it is worth, if I had to guess...  I'd say they took your filters out and did not replace them...   but that is just a guess & I say this because I knew a guy in the hearing aid industry that was re-molding non-customs to custom products.   He was a technician that had no clue regarding acoustics etc etc.
 
He had a cup full of dampers/filters...  that he had collected over a period of time... and he had no idea he what the were and thought they were needless so he just collecte them rather than place them in the coresponding tubing.
 
Just because you know how to make a hearing aid shell, does not mean you know how to make a CIEM. (but it is a good starting point)
 
Good luck to you.
 
Wizard
 
 
 

Unless the the BAs are vented, there is no acoustic chamber and even then it would only have to do with damping the bass. There is not enough length in any plane for anything related to acoustic bandwidths. Issues will have to do with mounting, (rigidty and conduction), relation of drivers, tips, tubes and filters in front of those drivers. There is way too much made of the effect of rear volume when it only has to do with bass tune on vented drivers. A driver can sound more open with less damping, but it's not the air behind that you're hearing.  A good example of this is that no IEM is front ported into the tip to add bass. It could only be used for cancelation because ther isn't enough acoustic space for reflex reinforcement. At best you could get a standing wave above 10k but that's easily mitigated.
 
Other than that, I agree with you and changing universals into customs is a crap shoot at best. Even if they use the filters, your changing from something that short tubes, tips and shallow insertion to long tubes, no tips and deep insetion. It would need different filters to sound similar.

 

[FullCircle]

The tube itself, is a chamber.
 
You change the tube in size, length, diameter, even the ID and OD relationship can change the sound.
 
The Ear Canal is also a chamber, and with a TF10, the chamber is longer, with a CIEM the chamber is shorter...  due to the deeper insertion into the ear canal.
 
Wizard
 
 

 

[MoAv]

I've actually had my filters on but when I tried without it sounded better.
Can you guys link me up for DYI's or any info about customs and acoustics ? I suspect that the lab picked the wrong tubing for the procedure, and I don't know if the housing should be empty and with no venting hole.

 

[FullCircle]

Housing for CIEMs that use Balance Armature Dirvers are empty, no venting is used. Tubeing is usually the same OD for a lot of companies, but in genearal the smaller OD should be used for bass & the larger ID for treble/mid.
 
Popular Damper colors for bass are:
 
Red & Orange
 
For mid to high:
 
Green
White
Gray

 

[MoAv]

Thanks FullCircle, where can one purchase those filters ? perhaps I'll be satisfied with just the right filters attached.

 

[scrane]

This is true. It's the same principle as a speaker's sound being dependent on it's placement and size of a room.
 
Quote:

The tube itself, is a chamber.
 
You change the tube in size, length, diameter, even the ID and OD relationship can change the sound.
 
The Ear Canal is also a chamber, and with a TF10, the chamber is longer, with a CIEM the chamber is shorter...  due to the deeper insertion into the ear canal.
 
Wizard
 
 

 

 

[goodvibes]

Quote:

This is true. It's the same principle as a speaker's sound being dependent on it's placement and size of a room.
 


 

Not the same at all. You place a speaker in a room to tune the bass standing waves/reinforcement and to control higher frequency reflections from boundaries. Basically tuning the midbass and stopping blurring respectively. In an in ear there are no standing wave below about 7khz and we are dealing mostly with pistonic resistance which is virtually a non issue in an open air speaker other than it's cabinet/port bass loading. Filters and tube diameter/length offer resistance for tuning but it's not chamber reflection. More resistance will damp the sound and highs in general. Any open volume like a straw can be called a chamber if you want to call it that and a larger one offers less resistance, a longer one more but calling it an acoustic chamber would be a little misleading and that's why I wanted to qualify things. In IEMs, the tubes are also generally the same diameter somewhere in their length to accommodate filters. There's a reason that filter values are given by resistance.

 

[FullCircle]

Quote:

Thanks FullCircle, where can one purchase those filters ? perhaps I'll be satisfied with just the right filters attached.

 
A guess,  OakTree Products, Westone, Warner Tech, Hal Hen, Knowles Electronics and maybe even Digi Key.
 
 

 

[scrane]

Quote:

Any open volume like a straw can be called a chamber if you want to call it that and a larger one offers less resistance, a longer one more but calling it an acoustic chamber would be a little misleading and that's why I wanted to qualify things.

Exactly.
If you don't want to call it an acoustic chamber, what should the space between the driver and the ear be called?

 

[goodvibes]

It's more like a pump extention with available resistance. There's nothing about the diameter or length that will cancel or reinforce audio wavelengths other than resistance and as I already said, you can call anything a chamber if you want to but that's clearly not the common usage or understanding of the term acoustic chamber. There generally more going on in all systems than what we know but that's the physics of it. Regardless of term used, it's certainly nothing like positioning a speaker in a room.

 

[scrane]

No matter the nomenclature, I think we can agree that submitting a pair of earphones to the guy down the street to convert into customs is a risky business. There is more to engineering earphones than drivers and crossovers. If this were not true there would be no endless discussion of "which tip is best?".
With reconstituted customs there's no fiddling around: it's either like it or lump it. And after spending the money with little potential for resale, most people will lean towards like it.

 

[goodvibes]

Can't argue with that.

I also think fitting universals into customs a bad idea. Lots to go wrong and how does one figure in conduction etc?