Quick rundown of easily-available isodynamics and their mods
Sorry I'm late to the party. Lets see if we can get AudioCats off the ground on his first iso adventure.
Edited by wualta - 9/10/11 at 8:20am
First, let me say it's difficult to rank these 'phones. Aside from trying to guess someone else's sonic/emotional/technical preferences, it very much depends on how much money you have, how long you want to wait to find a pair, and how much gluing and snipping you have a taste for. Having said that, I'll try to rank them by sound quality as I think they'd appear to a first-timer who's willing to mod, at the prices I paid. Note that I'm talking about models easily available in North America.
Fostex T50, available both as a Fostex and as an OEM clone under other names (NAD and Maior), but keep in mind that there are many variants and OEMs and they don't all sound like my example... which many of you would find bright. You have been warned. Heavy but reasonably comfortable. Open back. Supra-aural. Sounds like an SR-X Mk 3 with better bass. Only iso I've found that doesn't really require any modification. Easy enough to recommend, very very difficult to find, almost a phantom. Nice work if you can get it.
Fostex T30. Uncomfortable. Open back. Supra-aural. Needs modification (damping). Similar big (>60mm) diaphragm and magnet structure to the T50, so should have the most potential from modding but like the T50 very difficult to find. Obscure, so prices have been stupidly low. Did I say uncomfortable? Stupid design.
Yamaha YH-100. Comfortable closed-back (vented) supra-aural. With simple mods can sound very close to T50, which along with reasonable auction prices so far gives it high bang/buck ratio. 55mm nontensioned driver. Strong, deep, detailed bass when modded. Like all Yamahas of its era, heavy, floppy structure with weak points (don't drop 'em!) and moderately difficult to work on (lots of tiny screws; opposite earcup gets in your way, not a lot of room for experimenting with less-dense damping materials). Not much headstage. No longer reasonably priced when available at auction, and doesn't show up very often any more, a pity.
The next three are tied for fourth place, though the Pro 30 is a sentimental favorite and has shown such versatility in the hands of different modders, I'm strongly tempted to put it in 3rd-and-a-half place. I'm coming to love the two Fostexes-- excellent sound, rugged design, parts availability [update: this has become iffy] and availability at auction. The T40v1 is the only successful circumaural isodynamic. The YH/HP-1 are getting moby expensive, not quite as bad as the YH-100. The Pro 30's highs arguably aren't quite as sweet as the YH/HP-1's but it's very close, and it's amazing for the price-- assuming of course that you don't pay more than about ~$20. Here they are in random order:
Fostex T40v1/T20v2 ,not the mkII versions, nor the earliest (ca. 1978) T20. These are from Fostex's "middle period", 1986--2006. Comfortable; vented-closed back; not expensive new or used but not screamin' cheap either (say $50, give or take, used). T40v1 is circumaural (not my favorite style); T20v2 is, like its forebear, supra-aural with an earpad so large and poofy and enveloping that it approaches circumaural but isn't quite. Both models use a medium size (45mm) tensioned "dome" driver, factory damped (but in slightly different ways). Sound okay as-is, but treble is limpwristed and bass is blah-- however, with damping they are transformed. Fairly easy to work on-- good quality plastics are used even though the screws (3) are small. Uniquely, the driver itself is completely and easily disassemblable (!) (4 screws), though I haven't yet come up with a mod that takes advantage of this. Interestingly, the nominally closed T40v1 has no absorptive material in its cups (an opportunity!), but the supposedly less-closed T20v2 does.
The T20v2 turns out to have more mod wiggle room-- ie, it's easier to improve the whole frequency spectrum without sacrificing something on either extreme-- than the T40v1. Suggested T20v2 mod here.
For its part, the T40v1 can exhibit a keen, smooth high electrostaticlike treble without losing too much bass. See its very simple mod here. Semi-controversial "rings" mod here and here.]
Good safe starter isos due to rugged construction, simple disassembly and only moderate need to modify. Downside is unexciting sound out of the box, leading some owners who expected something that sounded like a Stax Lambda to abandon them prematurely, and a limited headstage due to the vented-closed construction. Note: the clamp that holds the driver together is built into the baffle, so removing the driver for a diy transplant operation is a major surgical procedure.
Yamaha YH-1/HP-1. Near as I can figure these are identical, with identical specs. Vented closed. Supra-aural. Comfortable (to me). 55mm nontensioned "pinch" driver. Bass not as powerful as YH-100 and modding potential is less, but fairly commonly available at auction, though prices seem to be rising out of the sweet spot. Like the YH-100 hard to work on but simple mods yield excellent results. Flimsy structurally. The HP/YH-2 have smaller drivers, but are seldom correspondingly cheaper at auction, plus they have reliability issues due to deteriorating foam (as ericj reported). The HP/YH-3 and the related HP-50 (and the mono-wired HP-50A) are YH-2-size drivers in a simple non-Bellini headset, as ericj mentioned above. Still worthy, but again, usually not much cheaper than the 1 and 2. Bah.
Realistic Pro 30 (vented-closed) and Audio-Technica ATH-2 (open). Supra-aural. The Realistic is one of the easiest to work on, with a low-impedance driver just efficient enough to use with some portable gear. ATH-2, with a similar (identical?) small (38mm) driver, has the tiniest screws you've ever seen for plastic (at least they're long) but is otherwise easy to work on; Pro 30 is so easy it's a wonder more manufacturers didn't make theirs this way. Both show up regularly but infrequently at auction. The Pro 30 is the cheapest iso available (~$10); ATH-2 attracts '70s collectors and goes for triple the price (although Headphile Larry got one for $3.40 + shipping). The plastic yoke holding the Pro 30's earcups is a structural weak point (avoided with an ugly but practical cable mod) and Radio Shack no longer stocks replacements.
Unless you want a big project, avoid the Mk II Fostex (T50RP and T20RP mkII and T40RP mkII) EXCEPT the most recent examples, which have a modified, flattened earpad. Well, even then, the mods are not a 10-minute job. Do a search for <T50RP> with recent dates.
Also be wary of the tempting B&O U70 (driver is extremely difficult to improve; expensive at auction) and get the Fostex T20v1 only if it's cheap (relatively narrow mod possibilities, lower efficiency, tendency to honk). Heck, "only-if-cheap" is good advice for avoiding disappointment with any vintage headphones. You heard it here first.
I've had very little success with any of the 'phones built by PMB (Peerless Mikrofonbau, a short-lived Danish-German combine) that have made it to The Lab: the U70, the Telefunken TH 700, the Goodmans OHP-10 and any German orthodynamics (eg, Dual). The PMB 100 was an exception, but its weak bass was a big No Thanks. But there are variant examples with different drivers and different damping, so your experience may be happier than mine.
The Yamaha YHD-1 and YHD-2 aren't quite as rare or expensive as their reputation has it, but they're not common, and they're problematic: the design is great to look at but sabotages the sound. YHD-1 is dull but at least has bass and shows promise for that reason-- you might be able to mod it without having to transplant it. Haven't heard the YHD-3, which resembles a miniature HP-3, but it has a conventional (and vented) earcup and might just be the antidote to all this highfalutin' design-- it might just have some bass. UPDATE: I just got a YHE-50S, which is to the YHD-3 what an HP-50 is to the HP-3. The YHE, like the YHD-3, is a YHD driver in a proper open-back earcup. The cute little earpads you see are apparently unique to the YHE, but in all other respects it resembles the YHD-3. The sound is dull and bassy, and damping may reduce the headstage, but this is encouraging, since it's the way the semilegendary YH-100 starts out. The YHD-3 could end up being the sleeper Ortho. Too bad it came at the end, and too bad the YHD series comes up for auction so seldom. The YHE is so rare I never expect to see another one that's not snatched by a certified orthoninja.
Note that the photo on the box makes it look like the YHD-3 has flat [cloth-clad foam?] earpads, as opposed to the little donuts on the YHE-50. This may make some difference to the bass output.
Great drivers, no matter how you slice it. Excellent candidates for a DIY transplant project, or just a damping mod if you can find the YHD-3 or YHE-50.
So depending on your patience and wallet, go first for the YH-100, and if you can't get that, the Pro 30. If you can't wait, get the Fostex T20v2. Waiting may well prove the deciding factor.
If you want top performance out of the box and are willing to both wait and pay for it, you'll want to get into a bidding war for a T50 or maybe a T30; I wouldn't recommend this gambit if you want to get started anytime soon. My very close second-favorite after those is the YH-100 simply because it can be tweaked around to sound good in such a variety of ways. In fact, it can be modded to have more bass and treble extension than the T50! I just wish it showed up at auction more often, as it did last year. The Pro 30 is just a lot of fun for almost no cash, and has a heroic little driver that stays up with the YH-100 in the bass until the last octave. The Fostexes mentioned here have some wonderful capabilities, but maintaining a balance between bass and treble is tricky when you're modding the T40. Heavily in their favor: just now the Fostex are the most plentiful iso out there.
Don't expect wide headstage from any of these. Do expect some of the cleanest, deepest bass you'll hear from a headphone, even if you have to EQ to get it, and smooth, extended highs that are downright electrostaticky-- after you do some mods. And most of these phones are so downright moddable, you may become an iso fan for that reason alone. You can learn a tremendous amount with just a bunch of felt and a screwdriver.
Does that help?