Fostex T50RP Incremental Mods and Measurements
Feb 26, 2021 at 4:37 PM Post #2,731 of 2,762

dnalekaw

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Hey everyone,

I´m absolutly new, maybe a bit late to the club. Is there any way these days to rebuild the Alpha Dog Mod?
Does the Alpha Dog Pads fit the the stock T50RP?

There are so many informations on the first site. Hard to complain everything.

Thank you
Recreating the alpha dog mod is pretty easy! You'd need to get open alpha cups somehow and some wool felt for the rear driver but apart from that there's nothing special about them - just follow the guide for the open alpha online. Of course you do need a t50rp mk2 though.

The alpha prime is the one with the pleated diaphragm, which in my opinion does nothing good for the sound.
 
Feb 27, 2021 at 3:05 AM Post #2,732 of 2,762

SeEnCreaTive

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Hey everyone,

I´m absolutly new, maybe a bit late to the club. Is there any way these days to rebuild the Alpha Dog Mod?
Does the Alpha Dog Pads fit the the stock T50RP?

There are so many informations on the first site. Hard to complain everything.

Thank you

Yes and yes

Search the forum for "Open Alpha" Dan himself (mr.speakers) released a slightly modified version of the actual Alpha dog files used for 3d printing to the community. Seriously 10/10 from Dan, he gained a customer for life on that one (considering my profile picture of course!)

I'm under the impression that the original alpha dogs had modified diaphragms. That is something that no one on this forum has attempted to my knowledge. Mostly due to ease of distroying the drivers. You can do the mayflower mod kit, or just get dampening materials and start experimenting. Alpha pads do fit the TxRP. I have used them. There are dekoni pads and tons of ebay stuff that will fit as well.

My understanding is they went through a bit more effort to match the drivers. T50rps are notorious for having unbalanced channels, but other than that the normal Alphas have regular diaphragms.

The Alpha Primes is when they started pleating the stock diaphragms as I'm assuming what you are referring to



My Ether CXs are off for service and my god do I miss them
 
Apr 23, 2021 at 10:38 AM Post #2,736 of 2,762

smorgar

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I recently got the T50rp and I have done the DVB#3 / Mayflower mod (they are the same right?) and I am very pleased with the results.
The problem I am facing is that the left driver has more clarity, not just more treble energy but its cleaner and more airy as well as more treble. This makes the headphone sound quite uneven and I'm not sure what to do about it. One way is to dampen the left driver so that it matches the right but I want to do it the other way around since the left driver sounds better with greater extension.

I have open them up a few time to check on everything and I just cant find a solution to my problem. I was thinking that the adhesive felt piece I put over the driver with the holes made in it was off in my cuttings so I re-did it and I made 110% sure that the pieces on each driver matches the other one. I even put the pieces on top of each other and like I said made them 110% match with mirrored positions for left/right driver and I was super anal about the position of the felt piece.

When I opened the cups for the first time I noticed a lot of glue on the paper behind the driver. Not sure if its ok like that but both drivers looks almost identical in this regard:
PXL_20210415_102805448.jpg
I'm playing with the idea that maybe I can remove the paper and just run the felt pieces, but on the other hand, the drivers looks the same in that regard... If I were to remove the paper I think it becomes a bass canon, but with the felt stuck on the back the paper would have about no effect besides the holes where the paper is showing? I'm thinking of covering the driver with transpore surgical tape to replace the glued up stock paper. Terrible idea or a good one?
PXL_20210423_123434113.jpg

I heard this problem before I began my mods and I know all drivers are note equal regarding performance, is that something that can be adjusted?
The problem was very small before the mod, it was almost borderline placebo. But after the mod the problem became more obvious to an annoying degree.

What can I do to try to lift the veil from my right driver?
 
Apr 23, 2021 at 11:35 AM Post #2,737 of 2,762

dnalekaw

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I recently got the T50rp and I have done the DVB#3 / Mayflower mod (they are the same right?) and I am very pleased with the results.
The problem I am facing is that the left driver has more clarity, not just more treble energy but its cleaner and more airy as well as more treble. This makes the headphone sound quite uneven and I'm not sure what to do about it. One way is to dampen the left driver so that it matches the right but I want to do it the other way around since the left driver sounds better with greater extension.

I have open them up a few time to check on everything and I just cant find a solution to my problem. I was thinking that the adhesive felt piece I put over the driver with the holes made in it was off in my cuttings so I re-did it and I made 110% sure that the pieces on each driver matches the other one. I even put the pieces on top of each other and like I said made them 110% match with mirrored positions for left/right driver and I was super anal about the position of the felt piece.

When I opened the cups for the first time I noticed a lot of glue on the paper behind the driver. Not sure if its ok like that but both drivers looks almost identical in this regard:
PXL_20210415_102805448.jpg
I'm playing with the idea that maybe I can remove the paper and just run the felt pieces, but on the other hand, the drivers looks the same in that regard... If I were to remove the paper I think it becomes a bass canon, but with the felt stuck on the back the paper would have about no effect besides the holes where the paper is showing? I'm thinking of covering the driver with transpore surgical tape to replace the glued up stock paper. Terrible idea or a good one?
PXL_20210423_123434113.jpg

I heard this problem before I began my mods and I know all drivers are note equal regarding performance, is that something that can be adjusted?
The problem was very small before the mod, it was almost borderline placebo. But after the mod the problem became more obvious to an annoying degree.

What can I do to try to lift the veil from my right driver?
Around the 3.5mm connection in the left cup there's a pretty large gap that will cause a channel imbalance if it isn't sealed, could very well be the cause for the difference you're hearing since its effect becomes more apparent with the more damping you apply. Some non-drying clay preset tightly around it will help with this as it's basically acting as an additional bass port.

Also fostex drivers have been atrocious with QC in recent years, despite the glue on rear driver paper I've never been able to replace it with something that doesn't muck up the sound horribly in some way shape or form. Transpore tape creates an awful 9~10 kHz peak and felt produces a large recession in the upper mids and destroys bass dynamics.

One thing to note too is that the DBV3 mod is only applicable to the mk2 t50.
 
Apr 23, 2021 at 11:43 AM Post #2,738 of 2,762

smorgar

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Around the 3.5mm connection in the left cup there's a pretty large gap that will cause a channel imbalance if it isn't sealed, could very well be the cause for the difference you're hearing since its effect becomes more apparent with the more damping you apply. Some non-drying clay preset tightly around it will help with this as it's basically acting as an additional bass port.

Also fostex drivers have been atrocious with QC in recent years, despite the glue on rear driver paper I've never been able to replace it with something that doesn't muck up the sound horribly in some way shape or form. Transpore tape creates an awful 9~10 kHz peak and felt produces a large recession in the upper mids and destroys bass dynamics.

One thing to note too is that the DBV3 mod is only applicable to the mk2 t50.
Thanks for the quick reply!

I have sealed both sides with blue tac, both the cable holes and the gap around the connector as well as sealed the baffle to the cup.
I think they sound fantastic, quite like my Etymotic ER4 actually. Very clean with tight groovy fast bass with a sub bass roll off that fits me perfectly :)
 
Apr 23, 2021 at 11:54 AM Post #2,739 of 2,762

smorgar

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Can I do something with the stuffing in the cup to increase midrange + highend? Or maybe close one of the 4 holes in the felt behind the driver to give it more treble reflection?
 
Apr 24, 2021 at 7:34 AM Post #2,740 of 2,762

smorgar

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I think I got as close to a solution that I can. What I did was to insert 2 small and super thin glossy plastic pieces from a chocolate box between the felt and the white fabric on the back of the driver. This lifted the midrange+highs a bit and I tweaked it until I got as close as I could to the left driver, according to my ears. I think the piece not really shown in the picture in the bottom right side did the most of the job since I put it so that it covered some of the bass vent on the back of the driver. This seems to have given the most mid+high end boost of the 2 pieces.
The lesser driver still didn't have quite the extension as the better one but now the mid+high energy was about the same:
PXL_20210424_095509140.jpg


I then played around with some different fabrics/paper and even some plastic net to try and match the drivers with all different combinations but nothing really did the trick.
I also think that maybe fabric 2 or 3 (counting from the top) would be a good replacement for the fabric on the back of the driver:
PXL_20210424_111934158.jpg

What I ended up doing is to put some transpore surgical tape on each driver to tune them closer and closer till I cant tell them apart anymore. Now I have to rest my ears and have a listen in a few hours to see if they sound properly :)
 
Apr 29, 2021 at 7:18 AM Post #2,741 of 2,762

smorgar

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Just to follow up: The day after my plastic piece mod i listened again and i realized the problem was still there. They day before my ears were just tired and probably some placebo since i wanted it to work out...
I measured the drivers via the cable and they had a difference of 6-7ohm (Left: 55, Right: 61,5). That explains the volume difference; the headphones are now on RMA.
 
Apr 29, 2021 at 7:46 AM Post #2,743 of 2,762

smorgar

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the modded one?
Yeah the modded one, but un-modded... Fingers crossed even though non of the mods would make the drivers behave like that.
[Edit] All went well in the end, got a new pair that measures within 1ohm, the pair i returned had a difference with 6-7ohm between the drivers. The new pair sounds epic but im experimenting with the felt thickness on the back of the driver. I feel that the bass is slightly boomy/big. Hunting that tightness. [/Edit]
 
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May 13, 2021 at 4:36 AM Post #2,745 of 2,762

smorgar

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