I want to be careful with this sensitive question, but these two:
http://i881.photobucket.com/albums/ac14/devouringone3/DSCN8048-1.jpg
http://i881.photobucket.com/albums/ac14/devouringone3/DSCN8044-1.jpg
(Head-Fi image uploader doesn't work for me, gives me an error, I'll try again later)
Sounds very much "the same" to me. I might be able to pick up differences in one of those tests I'm not allowed to talk to, but I'm really not sure (even by pushing up the volume they both hold themselves equally well).
Tubes influence and modulate the sound only when placed in front of the sounding element (drivers, vocal folds, etc.); at least more in a critical way. The two above headphones sounded much more different when backwards firing.
I think it was Arnaud who said somewhere in the Stax thread that cups geometry and/or material/mass (I don't remember which one exactly, or both, and I can't find the post in question :/ sorry) shouldn't matter, at all.
No-no, tubes will influence in either way. It's how T-lines and 1/4 waves work. The drivers are not perfect monopoles, they're closer to dipoles, there is an anti-phase backwave that is caught and modulated by the enclosure. That said, I would not expect massive sonic differences if we ripped up three pairs of RS-1 and had one in glass, one in metal, and one in wood (so I guess we'd only be ripping two up) of the same shape - the material used doesn't do a lot and since the tubes are so short it doesn't do much for the LF, that's on the driver. With true dipoles like STAX or planar magnetics the game changes substantially - you can't compare the two.
yeah, we definitely "hear" the enclosure in the HP1000. I know because I applied the foam mod to the inside of the aluminum wall on my old HP1000 and I heard shoutiness and glare in vocals drop by a noticeable amount. It's even measurable as purrin showed when he detailed the foam mods.
Yes.
And that's why Joe applies that goop to the inside walls. it may have slightly different damping characteristics to the foam but the idea is the same - reduce ringing caused by reflections in the enclosure. With Grados (old and new) this appears to be the 2 to 3 kHz region.
This too. I think the RS-1 have a feature around 5k as well, if I'm not mistaken. They are the only one that does that iirc, and I think it's a result of their different size/shape wrt the others. If you lined the inside with something like EPOM or Dynamat you'd influence heavily freqs where the material is absorptive, but it will become reflective at some point, and transparent at some point (as you move up or down, respecitvely). I think EPOM for example is effective around that 3-6k range, but at 20-30k it's likely more reflective, and at 20hz it might as well not be there.
Maybe that's because you're closing down the space, reducing the volume of the cylinder and in gets in the way of the sound? that has an effect, especially if it's Creatology foam
This too - which is part of the geometry argument. It's why closed headphones tend to lag behind open headphones in general, because among other things, they have to deal with that back-wave more directly than something like your RS-1 does. With "open air" designs (like the MDR-F1 and K1000) the baffle and any sort of lensing is basically all you have to influence the sound, and when you go to "open air dipoles" (like the SR-LNS or ESP/950) it's essentially free air for the driver - but if you dropped an ESP element in a big tube or a closed can (like the ESP/10) you can certainly change the sound. Same idea as the Fostex T50 modding - damping damping damping.
I wanted to talk about Grado cups materials... Geometry might change a little bit in the sound if it acts as a wall and "closes" the cups (or give a perpendicular surface for the sound to bounce on) or reduce their air volume.
The sound will bounce on the side-walls too - sure the driver is ringing and so on as well, but the "walls" of the cups are also interacting. The output is not linear, it's conical.
Maybe that edge has an influence, but the form/geometry the cups takes outside of that inner open air chamber (for example how the GS-PS-1000 cups protrude vertically) shouldn't change the sound at all. Again that is as long as we're talking about open back cylinders that do not invade the personal open space/volume of the cups, making them more "closed back".
True, I could hang Christmas ornaments or put the rubber duckies on the RS-1 and it wouldn't change them beyond comfort. But lengthening or shortening their chambers will.
Grado cups, as long as they're stiff enough (to not resonate), could be 10 cm long and I don't think the sound would be altered from stock version. The sound waves should travel mostly in a straight line.
No, they aren't straight-line. It's conical unless you have a parabolic or planar radiator. The Grado drivers are neither. They radiate out in a big cone and will have different on and off axis values (which don't matter much if at all because they're centered on your ear hole), and will interact with the enclosures and your noggin.
Yes you might hear a difference between having an enclosure and listening to the drivers in free air at a same distance, but changes to the cups geometry and materials around an unchanged "column of air" behind the drivers, shouldn't be audible IMO.
They will be. I'm not saying it will be BIG HUGE differences, but there will be differences. We are talking about roughly the same drivers and tuning after all; enclosures can only change a driver so much (e.g. look at my isobarik demonstrator; sure it brought THD down and changed MR, but it cannot fix the flaws associated with those super cheap drivers - just the same, you can't ever get the RS-1 to throw out bass like an XB1000).
Grado headphones, specially the HP-1000 thanks to their neutrality, are all very transparent, and do not have a proper baffle (if we're referring to the same "baffle", for instance the plastic structure where the T50RP drivers are screwed in).
The baffle is very small, and that's generally considered ideal in speaker building land. They're very clever.
but you're assuming that the sound waves are propogating in one direction like a column with no outward movement. But they are expanding outward and bouncing off the interior walls of the cups.
This.
purrin did some
tests on this matter, measuring SR80 drivers in different cups with or without foam plus with no cup at all. that's what led him to try the HP1000 foam mod to see if the ringing at 2 kHz could be reduced. The cups on grados make a difference. the material, the diameter and the length. Coating the inside of the cup with a damping material does affect the sound. the damping is the key factor, not the diameter change with the material since that change is minimal and the effect that is seen on the HP1000 is very specifically a damping issue. some excess energy is now absorbed by the foam.
This too. The driver's motor plays into damping as well - in other words some motors are better than others and can control themselves better. Crappy drivers will always be crappy, even in good enclosures, and good drivers will always be good drivers, even in crappy enclosures (but they won't "shine").
It's the same concept used on the HD800 foam damping mod to drop the treble region down a bit. different targeted frequency but similar materials and outcome.
Yup.
Yep I was aware of it
"Black - Martin Custom Cup w/ comfy pads
Red - Stock Grado Cup w/ comfy pads
Purple - Liberated SR80i Driver."
There's almost no (significant; we need to account for headphone placement) difference between Martin Custom wooden cups and Grado SR80i cups, except at 2 to 3 kHz, and the liberated drivers also act the same as with the cups starting at 3.5 kHz.
Yeah I'm not saying expect the RS-1 to turn into an ESW9 if you add a few CM of wood to them. But there is a difference at the HF which we can account for.
With the HD800 the mod happens between the drivers and your ears; with Grado the driver is at the front most and the mods happen behind it, for that reason I think it would be less effective... though I don't want to discredit the impact of a good Grado mod.
Sure; put comfies on the Grados and it will cut the sound down like nuts. Damping behind the driver is fairly trivial in an open-baffle system, especially if the tuning was done right at the factory, and I'm inclined to say that Grado put the hours in to get it right.
I didn't said "cups vs. no cups" would be hard to tell apart, or that modding and damping didn't influenced sound. I want to express that I think material for the cups (wood/metal/plastic) changes very little; and that the geometry itself, I'm not as sure, though as long as the air chamber behind the driver remains unchanged (geometrically), that there's a free cylindrical column of air for the sound to pass through and a fully open back to get out, sound shouldn't change either. (For example if you make your cups jumbo and wooden on the outside, or if you increase the length of your tube, there would be no change occurring on both the sound produced and perceived.)
The material doesn't do much, true. The geometry doesn't do a ton because Grado doesn't have big huge variations in their chambers - the RS-1 vs the SR-60 is probably about as dramatic as you can get without changing too many other variables, now if they had an RS-100 or something that used a 3' tube for the driver, that'd be another story.
If you line the tube with Creatology foam I agree it can change the sound a little bit yeah, because you're making an "obturation", closing the aperture, and I think drivers are quite sensitive to that, even if it accounts for very little in the final volume.
Yep.
Stuffed cups will sound stuffed, I think it's a principle behind damping, right?
Yes and no. The idea of damping is to resist resonance, or manage it, it can be active, passive, etc. Open-back designs tend to get away from this problem because the back-wave is sent off into free-space, but the chamber still influences the sound. The RS-1 vs RS-2 example is pertinent here.
I do hear that shoutiness/glare you're referring to... I will experiment with non-taped pads and see if my SR100-0 and SR325-0 also have the same problem, it will tell if it is really coming from the HP-1000 cups, or from any Grado cups (the drivers?).
Neat - let us know how it turns out!
I'm a driver fatalist, I think it's one responsible for both the qualities and the flaws, when the headphone is fully open. Sennheiser, Beyerdynamic, Audiotechnica, Stax, Koss, and more, I don't think they ever damped any of their cups will smooth materials the way Grado and T50RP modders do it.
Yes, the driver is ultimately your limiting factor. If it can't ring the bell (so to speak), it doesn't matter how nice the enclosure is. The manufacturers you've listed all use foam or fibre materials for damping, which most modders don't have access to (to fabricate) or find other materials to replace.
Not perfectly flat waves all going in the exact same direction but spreading in a similar pattern to the surface/relief of the diaphragm:
But still relatively planar and piston like.
No, that won't radiate along the lines of a planar or parabolic transducer - it radiates conically. All dynamic drivers do.
