TH900 mod extravaganza (stream of consciousness)

edit --- I misunderstood your paper mod. Looks pretty cool, have you been able to measure? Partial front damping is not a bad idea, though often times pad swaps or finding a way to swap the front foam rings can have a better effect without the need.

Otherwise, I see those Lawton cups defeat the air gap mechanism of the front mounting rings, which is generally awful for sound quality because tons of energy gets trapped inside the headphone - both the earside and within the cup. Kills dynamics, makes the sound super wet, resonant, ringy, lacks sustain in the sub area... I don't have tinnitus, but when I used cups with similar fit as what I see in those pics, it didn't jive with me on that front at all...

There's no foam involved with the 'sushi mod' which is basically a vent filter directly behind the rear driver outlet. It does nothing unless you tear off the paper that's covering the central driver vent. There's a pic of it above (quoted below), with some stiff adhesive felt and cotton. You can use any stiff adhesive felt, it's just there to keep the cotton in place. I just used cotton balls from CVS.

Did you mean foam for the front damping rings? It's just from Amazon, 7mm thick neoprene medium firm. Cutting it is the hard part!

 

Thank you, I did mean the front damping rings. They are not Lawton cups. They are cups I bought off of someone making them, on ebay. I think they have the same cutouts as the original cups. Or do you mean they mount more flush to the front mounting rings? I will look at maybe trying to add spacers and see what happens.
I have not started measuring with my MiniDSP EARS yet. I have just been comparing to other headphones I like with music, so far.

 

Spirit Headphones do offer an isobaric - http://www.spiritsoundesign.com/en#Twin-Pulse

I swear someone has attempted a PR in a headphone before. Tuning that thing in a lightweight moving chassis must be a PITA plus all the other challenges of miniature moving assemblies.

 

I've heard the Spirits before at trade shows in the past. Love the novelty factor, I just wish they sounded better! It does make more sense in a Grado-esque build where cup volume is minimal and everything's tightly packed.

The passive radiator cups have been a valuable learning experience with these Fostexes, but I think they'll find their best use in the upcoming scratch build I'm working on. Still a WIP, and my team is growing

At the end of the day, the cups that are the stock shape / size can achieve the best all-purpose tuning with the the materials I've tried so far, but I'm always tweaking with the more niche builds. Regardless, the air gap between the front of the baffle and the mount ring is absolutely crucial to getting lidless dynamics and effortless subsonic extension. I used some rubber feet like the ones that come with the smaller Schiit products as spacers on some of the cups that defeat the air gap, and results have been mixed - you'll need longer screws, and alignment is a PITA.

By the way, the stock screws suck, and I do suggest replacing them because they'll quickly stop holding if you often take apart and reassemble your cans. All the builds I've used take 2mm (M2) screws, with a length of 8mm (stock cups and mount rings), but I've used up to 14mm with the spacers. 10mm is a good size for the front mount rings - I use these https://www.amazon.com/gp/product/B07PNF45WB/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

@tommytakis has now heard several cup types and maybe can comment further.

 

At first I thought those looked neat, and then I saw the price...

 

Sorry for the divert but I demoed the Spirit for about 2 weeks with my DM Convert 2, and the Mogwai 2, the Phonitor 2 and the GSX-Mini as amps. My first reaction was "these are funky Grados". To the sound, they go very deep and the bass can be visceral where needed. To me, it was V-shaped but a little less zingy up top compared to the stock Fostex TH 900 v1.

 

@E_Schaaf thanks again. The cups came with longer screws. I can't seem to find the neoprene on Amazon. If it is not too much trouble do you have a link of what you purchased?
The only stuff I can find is either 1/4" or 3/8". Or EVA foam instead of neoprene.

 

@memoryerror 1/4 is good, and EVA is also good. Hope you've got a way to cut perfect circles because any imperfections in terms of seal with the front foams will kill the bass and yield narrow treble peaks. I do recommend a softer density, I have tried some very firm, nearly rigid foams and they give a little glare in the mids in comparison. 'Lazy Dog' brand is a good choice.

 

So there have been some rumors about the new freshly colored limited TH900s having a revised tuning for better sound. I called bullshit on there being any revisions, but turns out I'm wrong.

old stock TH900 -


'new and improved' stock LIMITED EDITION TH900 -


I am considering pressing charges against Foster corp for attempted murder over this revision.

In all seriousness - the 'new and improved' version features a plugged baffle vent (now no baffle venting). Kills the bass and also worsens the treble. I guess this change necessitated a new part number for the driver assembly as well - 548843 is now 631751. This will simply not do. Let's see how they mod (will follow up later today)

 

re: borked stock LTD TH900...

Responds to mods just like the others... (couple revisions) -

 

@E_Schaaf is you have a few extra foam dampening rings laying around I can take them off your hands

 

You can order that through Full Compass - Part # 1416449811 DAMPER, TH600 (TH900 ) 9.49 each

 

Sweet thanks

 

The new shoutier voicing looks like it's approaching the X00 actually, just with more lower treble than mid-treble. How badly does the perfect seal mess with the bass liveliness and texture? Foster must be losing it to be nerfing the one quality of the TH900 that's properly excellent.

 

I don't think Full Compass sells this part anymore. I cannot find it on their site.

 

It's on request with about 8 weeks of lead time just like every other Fostex part from Full Compass... Grr...