"Open Alpha" DIY project from MrSpeakers

I really enjoyed my Alpha Primes (bought used and not at their RRP at the time!). Some headphones I'm really nostalgic about.. definitely one of them.

 

Talk about nostalgia, while I was researching materials I came across the original T50RP mod thread from 2009 and saw so many old names and sbaf-ers.:
https://www.head-fi.org/threads/just-listened-to-some-fostex-t50rps-today-wow.452404/

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And sorry that I put you on the spot @zach915m . I swear I read second-hand years ago after mk3 was introduced that the new stock damping scheme wasnt an issue for ZMF because they remove the stock damping anyway so it didnt matter… I may have misremembered the company or it was false info.

 

Slow updates due to influx of new gear.

I used 1mmx5mm foam tape for the gasket. Easy:


This particular build is using an insert-screw edit of the original OA design. A little more complicated build but provides extra durability. I wish my Lawton Audio cups had insert screws…

 

Front-side is not the neatest. Paxmate is expensive but a friend kindly sent me a patch, insert screw set, and Angel Hair (100% organic, free-range). None of this stuff is absolutely necessary - just sharing my settings.

 

My 3Dprinter settings and technique werent the best either. Cup vents required some clearing of excess filament with a drill - used 1/16” if I recall correctly.

There are variants with different vent styles. The one shown above is original style. Another uses a screw mechanism to allow easy adjusting of venting to suit taste.

 

Its alive!

 

More drama and sense of occasion needed @Philimon. Got you covered mate.



PS - Loving this thread

 

Amazing, @Philimon. It'd be nice to have a dual-colour pair: red for port,green for starboard.

 

Fook Mundorf, fook ze Germans, there is only one Angel‘s hair:

You need to go, go, go:
YMO

 

Angel Hair is no joke.

 

First attempt, and using Dekoni leather pads (came with my Dekoni Blue). EARS:

This doesnt look so bad when compared against some of the mods measured by @DEATHxMACHINE . Do prefer to stock T60RP, TH500RP, T50RPmk2+3, T-X0, and Dekoni Blue.

Very enjoyable, non-fatiguing. Some treble presence dip but Im not so susceptible to missing personally. And the return on highs is non-fatiguing, its below mids and bass as it should. A tiny bit of presumably closed-back reverb, its a nice. Perhaps slight bass bloom, but preferable to the slight bass boom I was experiencing with stock mk3 baffles. For comparison LCDX might have slightest bass bloom too so Im going to try some velour pads but thats another thread. Really nice bass-mids!: good transition, levels, and detail.
- so many different damping mods and earpads so ymmv!

What I did here with my mk3 driver:
1. Remove stock damping paper from back of driver, doing so will dramatically reduce treble and highs. Should be able to get back to stock levels or some medium if you like with some careful experimenting, see T50RP mk3 sbaf thread I linked to earlier.
2. Stuff the cups with schtuff, but dont overdo otherwise you'll kill bass. Put lightest density stuff closest to driver is a oft shared theory. See the many mod threads - Im just pulling from them.

Spoiler: Paxmate

Spoiler: Arctic Cotton

Spoiler: felt

Spoiler: there

Could touch it up but I like the raw diy finish. And if I wasnt a newb printer I couldve made it all smoother from start.

I've a few other pads I can try. Update later when I have something better but even if I dont its still a really enjoyable headphone. At the least a fun diy and there is always EQ if i want more treble but its totally enjoyable as-is... Tonally preferable to stock LCDX, but LCDX is a level up in resolution. Open Alpha probably on level of HE500 and LCD2C, but dont quote me as I haven't a/b. T50RP bass different too as it's a closed back - imo a treat!

 

Based on @DEATHxMACHINE's measurements it was Modhouse that was removing the stock paper filters. ZMF was using front filters to reduce highs and there aint nothing wrong with that.

 

Is there a difference in drivers between the 20rp, 40rp and 50rp?

 

The drivers are identical except for the damping paper filter on the back. See Tyll’s detailed notes.: https://www.stereophile.com/content/diyers-delight-fostex-t50rp-mk3
There are some other differences between mk2 and mk3 enclosures but dont matter if youre building a full Open Alpha kit.

And the difference between 20/40/50rp are just whether the vents are open/semi/closed. People usually go with 50rp as its the open vent variant and you can easilly seal vents yourself if youd like to convert to closed. The others are sealed by the enclosure plastic mold so not so easy to convert vents to open.

 

Pretty sure it's just the covering of the rear cup vent that's different, not the drivers - and not the paper filter over the drivers, which is different between Mk2 & Mk3 models, but if I'm reading Tyll right, not between different variants of the Mk3.

See the T20 vs T40 Mk3 photos ("Inside the T40RP and T20RP...") in the Tyll link @Philimon posted.

Edit: and the cover (or not) over the pivot mount, also visible in one of those photos.

 

Besides the driver damping, the big difference between mk2 and mk3 is the driver baffle. mk3 baffle is different as it now includes a pad mounting ring and a different venting system which has an effect on bass +/-.

 

I have 1 spare set, in mango colorway and non-insert screw variant. FREE but requisite is you have to build and share impressions, for friends and contributors only. Does not include any extra parts and materials because Im all out. Not a simple install as the 3DP parts need finishing by removing supports and excess filament.

Spoiler: free

For ease I recommend Shapeways service because according to HF thread you get flawless prints with great quality material (ABS). Relatively expensive, not for bawlers. Id wait for ZMF which will be more expensive but fully sorted and wood.
https://www.shapeways.com/shops/mrspeakers

 

Removing the driver damper paper is irreversible or tricky to replicate with other materials. If you have a mk2 driver I would think twice because some people covet them so by removing the paper you are killing its $ value and they are hard to find now.

If you are suffering lagging bass:
- Make sure there are no gaps / air leaks. A sneaky spot could be between driver baffle and pad rings. Look at the seams under a flashlight.
- Make sure the cup vents arent occluded, driver needs some limited airflow.

DCA sells Alpha pads. Ive not tried them.:
https://danclarkaudio.com/alpha-pads-genuine-lamb-leather.html

 

No idea if titan mesh will work but it sounds like an idea. I am excited for your upcoming kit and Ill trade you a 2022 LCDX. Ive never heard a ZMF before. Is there any reason for you to go back to listen to old Vibro other than nostalgia or novelty especially now with Caldera?

 

Spoiler: Brainwavz hybrid oval VS Dekoni leather

Brainwavz hybrid clears up the little bit of bass bloom but adds a little sibilance to female vocals. Of course severity is track dependent so not always a problem. I prefer Dekoni leather because of the thunderous bass despite sounding obviously colored ... but sweet!

FPC mehsure:

Spoiler: Brainwavz hybrid oval VS Dekoni leather

Besides more pads I could try driver / cup damping to flatten response, or EQ. Ive been enjoying as-is so not too worried. a/b comparison vs HE6se soon.

edit: fixed graph, forgot to apply compensation