Fostex T50RP Incremental Mods and Measurements

[rudeboybass]

I ordered some shure brh-440m earpads to test. My boss purchased the headset and I noticed how much wider and deeper they are opposed to the SRH-840 pad. Anyone have experience with them on the t50?

 

[peter123]

Nice find, those pads looks great. Let us know how they work out when you get them.

 

[c61746961]

Very nice, the part is BCAEC440 for anyone interested.

 

[rudeboybass]

I searched amazon. Should be here in 2 weeks, I'm holding one in my hand now and it seems the foam/ fabric is thinner that covers the driver so I'm assuming there's less mid treble reduction that happens

 

[bluemonkeyflyer]

  What do you guys think about wm61a inside this ?

 
 
 
 

 
Looks interesting. You'll need a method for coupling the headphone to the prosthetic ear for a good seal.
 
I don't think this will work any better than other methods, just differently. You'll still be limited to comparing measurements you make relative to other measurements you make, not to others' measurements. 
 
I don't think  prosthetic ear will offer any benefits beyond those using simpler methods. Choose a setup, stick with it, learn its strengths and weaknesses, and learn how to interpret your data. Measurements are useful only when you understand how to interpret Your data which comes with personal experience with your kit.
 
~ BMF
 
 
Here's Solderdude's (Frans) PM about measurements...with permission to post:
 
Hi Keith,
 
Your answer there is spot on !
 
I have no idea IF that ear comes with a calibrated plot but I am pretty sure sticking a calibrated omnidirectional mic inside a tube (the earcanal) will also influence or at least alter the FR the mic receives, aside from what the Pinna and canal does.
I mean... I don't think if you mount an omnidirectional mic on a surface or in a tube the reference plot will be of much value as it was made in free-air. It won't be flat with a few dB peak around 16kHz any more is what I am getting at.
 
IF you intend to make absolute accurate measurements with it, it would have to be calibrated with a reference headphone that already is calibrated/known.
 
As a quick and dirty 'lets at least get a bit closer' practical method would be to measure 1 (preferably more) 'known' headphones.

Of course there are variances between them as well so unless you have the actual one that has been measured on a real calibrated rig (that is properly 'compensated') you will have to allow some errors.
The next 'hurdle' would be to know WHICH 'correction' the calibrated head did use to generate the plots ?
Did they use the Olive-Welti compensation, farfield or nearfield compensation ? something in between or custom ?
 
If you do not have access to a calibrated headphone a cheap method would be to use a 'well known' headphoneThe HD600/HD650 come to mind as excellent 'reference' phones for this.
You would have to allow for product variances though or perhaps lend one or more 'known' phones.

The next question would be WHO makes the best 'reference' measurements that come closest to the reality ?
The manufacturer ? Tyll ? Purrin ? Ultrabike ? Rin Choi ? Golden ears ? Stereophile ?about.com ? review.com ? any of the Russian, Korean or Japanese sites ? or even others ?
Did they use the Olive-Welti compensation, farfield or nearfield compensation ? something in between or custom or publish raw plots ? Does one know which compensation was used on any of those sites ?
 
In any case you will be able to compare your own measurements against those of your own and see what the changes are you actually made when modding. How close your plot will turn out to be to what's really happening will thus depend on a load of factors aside from the (invalid ?) calibrated mic and needed compensation for THAT specific 'ear'.
 
Lots of research and overlaying plots (by stretching plots so they have the exact same scale !) may teach you what you are looking for.

kind regards,
 
Frans

 

[bluemonkeyflyer]

Here's a "Solderdude Frans" phantom power supply I built for a good friend. 
 
   
 
   
 
Resistors: 6.8, 2.2, 100 kOhm
Capacitors: 4.7 and 100 uF
3.5 mm TRS jacks (wired for Mono per REW requirements): Left jack = Mic IN, Right jack = Signal OUT to sound card
All connections tested with DMM and super glued in place
Metal tin for shielding
Circuit grounded to metal tin
 
Works great with REW and Panasonic WM61-A omnidirectional mic capsule.
Low noise floor.
Easy to build.
 
Thanks, Frans!

 

[Thujone]

Man, I love Frans. He's all about helping the community by sharing his knowledge. Not to mention the great Garage1217 products!

 

[bluemonkeyflyer]

  Man, I love Frans. He's all about helping the community by sharing his knowledge. Not to mention the great Garage1217 products!

I do, too! Frans has been very helpful to me in many ways over the past year. I'm amazed by his detailed and clear explanations and willingness to take so much time to help. We tried each other's measurement setups using WM61-A mics and REW and have had interesting discussions on his web site and by PM. His phantom power supply pre-amp is the best I've used.
 
Frans' web site with many useful threads and tips. My favorite is Solderdude's Tech.
 
Frans' web site measurement rig thread
 
P.S. I love my Project Ember amp with Telefunken E88CC

 

[waynes world]

A buddy of mine modded my T50RP's for me. BMF, you may know the lad, and maybe one of these days he will honour us with the details
"right about here ----> ****** <----" lol.
 
Anyway, I am no T50RP expert (I don't know what they sound like stock, or sound like in other modding configs). And I'm not very familiar with orthos except for my TDS16's. But, I felt the need to express my joy regarding these modded T50's. What a huge, bold, articulate and engaging sound. Just fantastic.
 
The T50RP's are amazing. You modsters are amazing. And my friggin' pair is really amazing! 
 
Cheers!

 

 

[mrsantarina]

DBV#3 mods with alpha pads is it good? or just stick with shure 840?

 

[nick n]

waynes world  as far as comparing to others, the stuff in it is unguessable as far as specific arrangements of things and materials, Way different than the earlier posted version.
It'd be great if you could compare to others somehow some way. Maybe hit up a meet at some point. Seriously you could buy another stock one and now that you are started on the modding path somewhat, walk through the DBV#3 mod it is a nice step by step procedure very easy thanks to BMF and his meticulous documentation. Help is only a pm or post away . it is definitely a worthy adversary. make me sweat some more ....
 
 
 

 

[Thujone]

  DBV#3 mods with alpha pads is it good? or just stick with shure 840?

It sounds pretty bad with the Alpha pads. You will have to do quite a bit of tuning.

 

[mrsantarina]

What will be the best pad for it? I'm new to tuning and modding.. Any better and comfortable pads for it?

 

[Thujone]

Every pad will change the sound in their own way. If you want to follow this guide, use the pads suggested in the guide (840 pads). I personally find the 840 pads to be very comfortable.

 

[abhinit90]

If I may add, I like the HM5 pads a lot too. Pretty comfortable too, better than the HiFiMan pads (not velour) that I had earlier.