Skip down to the bottom of this post for loaner terms and signup. Please post your approximate location as well as a 1-2 sentence statement of interest as to why you're a suitable tour candidate. I already went into detail about my vision for this project on a few threads (linked below), but as an overview for this loaner signup I thought I’d come up with a corny intro that sums up the idea behind this headphone along with a description of the modifications done to the headphone to get it to sound the way that it does. reference threads - https://www.superbestaudiofriends.org/index.php?threads/esx900-impressions-slamhead’s-delight.9777/#post-314605 https://www.superbestaudiofriends.o...od-extravaganza-stream-of-consciousness.9452/ INTRO In a world… Where face-tweeters with massive treble peaks (don’t make me make a list) are considered some of the world’s best… Where closed-backs almost always have squiggly, unlistenable tone… Where few headphones give both satisfying sub bass and also great kick with controlled treble (looking at you, planars)... Where few decent-sounding full-sized headphones can be driven well by a portable device… Where pop music and lean recordings can only be enjoyed at low volume without fatigue… Where few headphones can make sense of a high bpm double kick… Where decent tonal translation between speakers and headphones is considered near-impossible... enter the ESX900. WHAT IS ESX900? This headphone is a completely overhauled vision of the 548843 driver made by Foster for Fostex’s use in the TH900 headphone. I’ve renamed this headphone ESX900 and not simply ‘modded TH900’ because it has been modded in literally 16 sonically significant ways and deviates quite a bit from the sound of the stock TH900. All that is shared is Foster’s drive element and the headband assembly (which I might swap at a future time). This particular tour features a headphone voiced to DEATHxMACHINE’s ambitious vision - (paraphrased) ‘I want EDM to be enjoyable near 100dB’. I’ll leave it to the community to decide whether these mods approach the very lofty goals, but after 9 months of daily exploration, hundreds of hours (and dollars) sunk into materials cost and labor, I feel this headphone has many unique things to offer. This is an ongoing project, and every ESX900 will be different according to the desires of who I’m making it for. My rate is very competitive compared to other custom modders, and I don’t charge for labor until you’re satisfied with the tuning. If you’re interested in my work, send me a DM. DESCRIPTION OF MODS: Exterior - Audio Technica AP2000Ti pads, mounted upside-down (thicker on top) Geekria headband cover (stock headband was flaking) Palo Santo unfinished cups (same dimensions / spec as stock Fostex cups) Alternative cup designs (deeper, vented, passive radiator, etc) are possible and can be made to custom spec. Lots of tunability here. Going with a ‘normal’ cup shape on this tour shows what’s possible to those not interested in shelling out extra for custom cups. I can work with stock cups for a similar result. Headband / Pad Mount assembly - Double-stick tape pad mounting to improve seal Taped over stock mount latch holes to improve seal Snipped mounting ring nubs for direct coupling Removed cable outlet rubber sealer Slightly larger (wider and longer) baffle mounting screws for improved hold and longevity Front of baffle / ‘earside’ - Custom die-cut non-vented medium density neoprene rings 75mm outer diameter, 50mm cutout diameter Recommended for use WITH pseudovent mod (below) Can be tweaked to shift frequency and degree of bass emphasis Sealed stock baffle vent via paper tape Light front filter behind pad hairscreen (optional) While front dampers are generally rightly frowned upon, in this case I found it necessary for control at very high SPL. I spent more time tweaking this than anything else aside from cup stuffing. Filter works well with these pads for a generally superior result compared to the pancake pads with no front damper, which measures similarly. Opening of rear driver vents made the headphones dynamically livelier than stock. Like a snare drum hitting 10mm from your face, had my ears ringing. This brings back the control without losing scale or extension. Rear of baffle / driver assembly - 11/11 open rear driver vents (stock is 2/11 open, completely configurable for preferred high frequency response and wood timbre) Allows cups to impart more color and provides a ‘room response’ for a more speaker-like sense of dynamic tactility. NOT RECOMMENDED with unstuffed cups or without pseudovent / baffle seal mod (below) Reduces treble quantity and peaks ‘Sushi Mod’ - primary magnet vent height extension and filter with rigid adhesive felt and tightly packed cotton Opening up the central driver vent normally results in a MASSIVE 20dB dip around 2.5-4.5khz. Sushi mod narrows and minimizes this dip while keeping the strengths of the open vent (improved bass tactility and sustain, reduced low treble peaks) ‘Pseudovent Mod’ - 4 pieces of weighted thick tape near cup-mounting screw holes to induce a ~.5mm air gap between the rear of the baffle and the cup when mounted. Longer cup mounting screws required. Provides pressure escape from driver backwave, which is now dramatically enhanced by rear driver venting. Reels in midrange resonance and reduces treble ringing but maintains extended sustain and ‘room response’ in low bass. Complementary mod to non-vented front baffle rings and sealed baffle vents for improved lower midrange linearity Cup stuffing - Thin strip of dynamat-like goop (3mm) around circumference of cup closest to baffle mount Porous open-cell coarse foam bottom layer around cup side walls. Donut shape, ~1mm deep - not covering the back cup wall. Two strips of extra thick adhesive felt with parallel placement on the outer sides of the flattened back cup wall. One strip of extra thin polyester felt between the thicker strips, through the center of the back wall. Cotton stuffing (preferred over acoustic wool) packed in an attenuated cone shape - thicker on the sides, thinner in the middle, none in the center over the felt from (3) and (4) Disclaimer - this is a fickle recipe of tweaks that all work together towards a synergistic end. Some of these mods are irreversible and can easily irreparably damage your headphones if improperly executed. While I support DIY, don’t hold me liable for any accidents or poor results yielded from trying similar experiments yourself. LOANER TERMS: This is considered a personal loaner by DEATHxMACHINE (owner). He agreed to send this pair on tour in exchange for free modification work aside from the cost of the cups. These are the terms: 1. 5 to 10 established Friends (plus interested Staff Members) only. USA48 only. Ideally those who are potentially interested in seeking modification services in the future. 2. The tour will be broken into two legs, with a short break for Marv to measure and post impressions whenever is most convenient to him. DEATHxMACHINE may request a position in the tour at any point. If the headphone needs repair or tuning is unsatisfactory, it can return to E_Schaaf for a tune-up at any time. 3. 5 day review period with posted impressions in the ESX900 impressions thread - https://www.superbestaudiofriends.org/index.php?threads/esx900-impressions-slamhead’s-delight.9777/ 4. Shipping using Fedex or UPS with $1000 insurance and signature required. 5. Absolutely zero disassembly, including pad rolling. ROSTER: I'll populate this list according to geographical location once we get enough interest - a day or two. I'll tag you when it's finalized, but will continually edit this list as a placeholder until we can fill this up. You may be moved around or booted per discretion of DEATHxMACHINE. x. DEATHxMACHINE (WA) 1. @Inoculator (WA) x. @ChaChaRealSmooth (CA) x. @purr1n (CA) 2. @famish99 (TX) 3. @SoupRKnowva (TX) 4. @Phantaminum (TX) 5. @dubharmonic (IL) 6. @dncnexus (MD) - skip 7. @Vtory (PA) 8. @skem (MA) 9. 10. __________________________________________ One last listening note - with this tuning, there might be some brain burn-in given the strong downslope. If the listening experience is lackluster, try branching out and exploring different types of music, or turning up the volume just a little bit. Seal is important, and the pads are at a bit of a tilt by design, so the headband might sit further forward or backward on your head than other headphones for optimal angling. This particular unit is built to a specific vision, though I have tremendously enjoyed it as a daily driver with a wide scope of content as well. ***edit - the headphone is hard-wired to 1/4"*** If you'll be measuring the headphone, keep in mind you may have to apply gentle pressure to get a good seal. Positioning relative to pinna on EARS will have a DRAMATIC EFFECT on measured treble, though on the head with a good seal it doesn't audibly shift. I am most interested in flat plate and non-EARS measurements. Thank you @DEATHxMACHINE and @ChaChaRealSmooth for facilitating this tour. @purr1n feel free to request a detour to your place at any time when you’re available for evaluation. I know you’re busy with some other stuff ChaCha just sent your way. Cheers!