Just listened to some Fostex T50RPs today... WOW!

[sling5s]

What is the basic difference in sound with putty on the all the baffle compartments vs with compartments unfilled except around the driver?
 
Quote:

BMF 6v3: Less Is More?

 

I think Fostex purposely put the partitions and odd compartment shapes on the back of the baffles as an important part of the acoustic design. If so, filling them with plasticine may not be the best approach when modding.

 

This configuration was tuned with Audeze LCD2 as the reference. The sound signature is the same. The SQ is very close but the LCD2 with 5 times the driver size, 10 times the cost, and open design wins every time, IMO. That said, these sound really good to me for < $100.

 

1. BMF Tungsten Putty surrounding the driver on the back side of the baffle.

2. Back baffle panels and compartments unobstructed and unfilled.

3. Paxmate Plus in the interior cup floor, only.

4. Central chamber for headband hanger screw uncovered.

5. Stock white driver felt intact and in place. Reflex dot, tape, or felt tuning is optional.

6. Stock black bass port felt intact and in place. Bass port tuning is optional.

7. Dust cover chiseled off around the ear side of the driver; dust cover in place over driver.

8. One layer of Dynamat surrounding the ear side of the driver.

9. One layer of self-adhesive felt over the Dynamat.

10.Shure 840 pads.

 

 

My tungsten putty recipe surrounds the drivers. The baffle panels and compartments are unobstructed. White specks: residue left over after removing white plasticine from a previous mod. Paxmate Plus in the cup floor, only. Stock black bass port felt and white driver felt intact. Plasticine in the outer cup rim from a previous mod.

 

 

 

 

After chiseling off the dust cover, I cut and placed 4 pieces of Dynamat surrounding the driver. The dust cover is in place over the driver. Cardboard template for cutting out the felt cover in the next photo.

 

 

 

 

Self-adhesive felt over Dynamat to seal the goo and lift the ear pads. Notch cut for baffle equalization vent. Additional ear pad lifting with gauze is optional.

 

 

 

 

One large cotton ball pulled apart and placed in the cup over the Paxmate. This gives a different sound but not necessarily better than "empty."

 

 

 

 

Shure 840 pads. Additional pad lifting with gauze, etc., optional. They look better than stock but I think stock pads with rear lifters sound just as good and are just as comfortable.
 

 

 

[BmWr75]

Quote:

What is the basic difference in sound with putty on the all the baffle compartments vs with compartments unfilled except around the driver?
 

I've been thinking about this question and remembered Newton's 3rd law of motion from college.
 

[size=medium]For every action there is an equal and opposite reaction.[/size]

 
So, when the driver in the T50RPs vibrates, there a two possible reactions.  1. the driver can move air and create a sound wave.  2. the plastic housing in which the driver is mounted can move and create an unwanted resonance/vibration.
 
In actuality, both of the reactions are happening at once.  The most desirable outcome is reaction 1, where the driver energy is converted to sound and none is converted to housing resonance.
 
Mass loading the back side of plastic housing makes it harder for the driver to vibrate it because it weighs more, as does installing Dynamat/Fatmat on the earside of the housing, therefore reducing unwanted resonance.  
 
Newton's second law Force = Mass * Acceleration is coming into play here also because the force the driver can impart to the plastic housing is fixed.  So, as you increase the mass of the housing, its potential to accelerate (i.e., vibrate) is reduced.

 

[sling5s]

I tried it both I definitely prefer the a partial filling of just around the edges of the driver on the baffle.  
This way, it sounds like the LCD-2 rev.2 while when all the compartments are filled, it sounds like the LCD-2 rev.1.
Leaving the compartments unfilled produces a more vivid, lively, upfront midrange.
 
Quote:

What is the basic difference in sound with putty on the all the baffle compartments vs with compartments unfilled except around the driver?
 


 

 

 

[rhythmdevils]

You think adding more putty makes them warmer?  Not my experience at all.  And the T50rp sounds very different from the Audeze to me.  Different ears I guess. 

 

[sling5s]

Originally Posted by bluemonkeyflyer /img/forum/go_quote.gif

BMF 6v3: Less Is More?

"I think Fostex purposely put the partitions and odd compartment shapes on the back of the baffles as an important part of the acoustic design. If so, filling them with plasticine may not be the best approach when modding."
 
I was using the LCD-2 rev.1 and LCD-2 rev.2 as a reference but the reason I like the Fostex T50RP is that they don't have the same sound signature as the LCD-2.
While I lauded the technical feat of the LCD-2, I just didn't like the relaxed sound signature, especially in the midrange (upper midrange to be exact).
I find the Fostex T50RP, more to my liking, more lively, more energy, more upfront midrange presentation (more like AKG K240 Sextett & ATH-AD2000).
 
As for putty, I could be wrong....I only gave a short listen... but I found having less modeling clay gave it a more airy and lively presentation.  When the modeling clay was increased, things did get smoother, tighter, but I missed the more upfront and lively midrange.  My impressions might have been too short...but I was going by what bluemonkeyflyer had done with his BMF 6.3 version (less is more approach) where he took out the putty in the compartments outside the driver and only had it in the ring surrounding the driver.  
 
 

Quote:

You think adding more putty makes them warmer?  Not my experience at all.  And the T50rp sounds very different from the Audeze to me.  Different ears I guess. 

 

 

[cn11]

I think my modded T50RP has about the perfect balance of detail and nuance, and livliness. Much more relaxed, and things would be dull sounding, yet it's never harsh at all and presents amazing detail and separation. 

 

[c61746961]

I've been modding these for the last month, all reversible mods and so far I've settled with:

Stock felt over bass vents.
Stock paper on backside of the driver.
Ear-facing felt removed.
Ear-facing baffle dampened with some sticky, foamy furniture feet pieces (no access to acoustic foam in my country)
SRH840 pads with 5mm risers on the back side (was higher before but this only increased the 1KHz resonance and attenuated the upper midrange even more)
Dampening on the back side of the cups with some caulking sticky tape.
A 4mm layer of cellulose foam over that with a hole cut over the bass vents.
A semi dense layer of cotton, less dense over the bass vents.
Playing with electrical tape over the bass vents yielded pretty subtle changes and did not really improve the bass impact / extension for me.

...but I'm still to find a way to fully eliminate the 1 KHz peak (tried increasing cotton amounts but all I accomplished was reducing the soundstage and bass presence), increase the upper midrange region energy and increase the sub-bass.. I have no trouble hearing it down to ~35 Hz, but it's definitely not on the level of some graphs I've seen here and elsewhere, also, the impact is a little bit less than my Grado SR80 with REALLY worn donuts (think saggy old socks), I was expecting more but perhaps I'm just not being realistic. Any ideas?

 

[hans030390]

Quote:

I've been modding these for the last month, all reversible mods and so far I've settled with:
Stock felt over bass vents.
Stock paper on backside of the driver.
Ear-facing felt removed.
Ear-facing baffle dampened with some sticky, foamy furniture feet pieces (no access to acoustic foam in my country)
SRH840 pads with 5mm risers on the back side (was higher before but this only increased the 1KHz resonance and attenuated the upper midrange even more)
Dampening on the back side of the cups with some caulking sticky tape.
A 4mm layer of cellulose foam over that with a hole cut over the bass vents.
A semi dense layer of cotton, less dense over the bass vents.
Playing with electrical tape over the bass vents yielded pretty subtle changes and did not really improve the bass impact / extension for me.
...but I'm still to find a way to fully eliminate the 1 KHz peak (tried increasing cotton amounts but all I accomplished was reducing the soundstage and bass presence), increase the upper midrange region energy and increase the sub-bass.. I have no trouble hearing it down to ~35 Hz, but it's definitely not on the level of some graphs I've seen here and elsewhere, also, the impact is a little bit less than my Grado SR80 with REALLY worn donuts (think saggy old socks), I was expecting more but perhaps I'm just not being realistic. Any ideas?

The only way I was able to get strong bass from these was to remove the stock paper/felt from the back of the drivers and then either A) cover one or two open squares with electrical tape or B) using 3mm felt (75% wool, 25% fiber) over the back of the driver with a square hole cut out of the middle (see my previous posts for details, available in the T50RP mod links wiki). I would also suggest removing the risers from the 840 earpads, which made the sound more "lush" for me (more bass is one part of this).
 
Taping the vents doesn't do as much with the stock driver paper/felt and stock vent felt in place.
 

 

[c61746961]

Thanks!, oh, and one more thing, I have these currently connected to an oldish pro-audio headphone amp which happens to have a 160-ohm output impedance, has anyone had negative experiences using relatively efficient orthodynamics to equipment like this?, I also built an adapter for the speaker outputs of my integrated amp, but there's annoying buzz (kinda like a 60 hz square wave) in the background, anyone knows what's causing this or how to alleviate it?

 

[RexAeterna]

You think adding more putty makes them warmer?  Not my experience at all.  And the T50rp sounds very different from the Audeze to me.  Different ears I guess. 

if you want them warm sounding. leave them stock way they are and just replace the pads. they are actually very listenable and enjoyable once you replace the pads alone and cause it distance the driver bit farther from the ears.

 

[hans030390]

Quote:

Thanks!, oh, and one more thing, I have these currently connected to an oldish pro-audio headphone amp which happens to have a 160-ohm output impedance, has anyone had negative experiences using relatively efficient orthodynamics to equipment like this?, I also built an adapter for the speaker outputs of my integrated amp, but there's annoying buzz (kinda like a 60 hz square wave) in the background, anyone knows what's causing this or how to alleviate it?

From what I can remember, you want the amp's output impedance to be...one eighth or less of your headphone's impedance...? I think that's what I read. I don't know if this will cause any problems or not, but you might not be getting the best listening experience with it.
 

 

[rawrster]

Quote:

I think my modded T50RP has about the perfect balance of detail and nuance, and livliness. Much more relaxed, and things would be dull sounding, yet it's never harsh at all and presents amazing detail and separation. 

I'm glad you like yours. I'm going to have to do some house cleaning soon so that I can use my T50RP more often. They are quite comfortable at least with my O2 pads and sound quite nice when driven by a good amp. They don't seem very picky and sound good with everything I've tried on them but they sound amazing on some amps with good synergy with the T50RP.
 
I just wish it had a better headband. I think I may try the Grado stock heaband and use LFF's suspension mod when the headband for my Magnums have come in the mail.

 

[hans030390]

Quote:

I'm glad you like yours. I'm going to have to do some house cleaning soon so that I can use my T50RP more often. They are quite comfortable at least with my O2 pads and sound quite nice when driven by a good amp. They don't seem very picky and sound good with everything I've tried on them but they sound amazing on some amps with good synergy with the T50RP.
 
I just wish it had a better headband. I think I may try the Grado stock heaband and use LFF's suspension mod when the headband for my Magnums have come in the mail.

Or you could do the suspension headband mod now. Slap one of the stock T50RP earpads onto the underside of the suspension headband as well for crazy stupid comfort.
 
I am not liable for the bad headphone hair you'll have after.
 

 

[sling5s]

Which is why I love the Fostex T50RP and why I sold the LCD-2.  The LCD-2 is technically better but just too relaxed for me.
I didn't think I would like a headphone as much as I like Magnums (modded Grados) but I just can't stop listening to them for vocals.  The vocals are simply amazing...like they are singing right at your ear.
I love Grados for rock but for vocals, nothing compares to the Fostex T50RP.
Quote:

I think my modded T50RP has about the perfect balance of detail and nuance, and livliness. Much more relaxed, and things would be dull sounding, yet it's never harsh at all and presents amazing detail and separation. 

 

 

[cn11]

Yes, mids are wonderful for sure. But the thing which amazes me more even is the treble detail, without being remotely harsh. I mean, it's damn near perfect to these ears. It's just so wonderfully extended- I sure don't hear any roll off at all. Maybe the inherent black background helps in that regard. If these are this nice, then I can't wait to hear lokesen's KODA^2 (if they ever clear customs... arrrrrggghhh).