Attn owners of the ISK MDH9000 and it's many clones (Akai Project 50X, Marantz MPH-2, LyxPro HAS-30, Freeboss MDH9000).
I have completed a few mods that you may be interested in.
1. Tuning paper mod
The stock tuning paper is extremely restrictive, and very little passes through it. This mod allows a more spacious sound. You have to be very careful not to poke the driver diaphragm when perfoming this mod. I used the very tip of an xacto knife, and carefully trimmed each circle. You could also maybe poke each hole out with a philips screwdriver, and peel the paper away with tweezers. But I repeat, you MUST BE CAREFUL not to poke the driver diaphragm when perfoming this mod. I wish you could just peel or scrape the tuning paper off in 1 big piece, but the whole thing is held on with some sort of evil mutant glue, and the tuning paper doesn't peel at all (it must be trimmed off).
2. Locking cable elimination mod
This eliminates the cable lock, allowing the use of any 3.5mm cable that is slim enough to fit inside of the hole (for example, a Beats cable). Note that you will still be able to use the stock locking cables as well. This mod just gives you the flexibility to use any cable that physically fits.
- On the L earcup, remove the earpad and remove the (4) screws that hold the cup together.
- Remove the (2) screws that hold the little circuit board down, and lift the circuit board out of the way.
- Remove the (2) screws that hold the locking mechanism down, and remove the plastic locking mechanism piece.
- If you look at the plastic locking mechanism, you’ll see the (2) small plastic locking tabs (on the top and bottom). Break both of them off using pliers, a screw driver, or some sort of pokey-pokey tool (like a scratch awl). The plastic is very brittle, and the tabs will break off with little effort.
- Reinstall the locking mechanism back on and secure it with the (2) screws.
- Reinstall the circuit board back on and secure it with the (2) screws.
- Make sure a regular, non-locking 3.5mm cable plugs in smoothly. If for some reason it doesn't that means you didn't break off the locking tabs completely. Go back and double check, and correct the issue until a regular, non-locking 3.5mm cable plugs in smoothly.
- Put the cup back together and secure it with the (4) screws.
- Put the earpad back on.
3. Semi-open mod (stealth venting)
One of the reasons why the soundstage in these cans is so good is because the cup has a number of hidden vent holes. If you look at the 12-o'clock position on each cup, you will see (7) tiny vent holes inside of a small "groove". I took this idea and extended it, adding holes completely around the cup, also hidden inside of the groove. The result was an even wider soundstage than before, and additional sub bass extension that is much deeper than the stock version.
- On each earcup, remove the earpad and remove the (4) screws that hold the cup together.
- Put a piece of tape over the vent hold on the driver magnet, to prevent debris from falling into the vent hole.
- Using a small drill bit (ie the same size as the existing (7) vent holes in the 12-o'clock position), drill additional holes inside of the groove, all the way around the driver cup. Space the holes a few mm apart (use the (7) stock vent holes as a guide to about how far apart to space the new vent holes). Note that you will have to skip a few sections where you won't be drilling any holes, such as the (4) cup mounting screw posts, the (2) yoke mounting blocks, and the aux cable area (I've indicated these with arrows in the 1st photo below).
- Blow all of the plastic chips away using your breath, canned duster air, a brush, etc.
- Make sure all of the holes are clean and free of loose hanging plastic pieces (that could later fall off and get inside of the driver). This process took quite a bit of time, as it's critical to make sure every last tiny loose plastic piece is cleaned up and accounted for.
- Once you are pleased with the results, remove the tape from the driver magnet.
- Put the cups back together, and replace the (4) screws.
- Put the earpads back on.
- Repeat the procedure on the other side.
4. Semi-open mod (grille mod)
One of the reasons why the soundstage in these cans is so good is because the cup has a number of hidden vent holes. If you look at the 12-o'clock position on each cup, you will see (7) tiny vent holes inside of a small "groove".
I took this idea and extended it to it's maximum conclusion, replacing the alumium name plate with an open mesh grille.
The result was an even wider soundstage than the #3 mod above, an increase in sub bass quantity, AND further sub bass extension (than the #3 mod above). WoW!!
You may be asking yourself, "
how can Slater do #4 without knowing what effect #3 had?" Simple, I taped the small hidden vents closed before completing mod #4. You won't need to do this, as you'll either do mod #3 OR mod #4 but NOT both. I only had to do this because when tuning and developing mods you often do extra stuff, make mistakes, go back and undo things you;ve already done, etc as you play "what if" with the tuning.
These 50mm drivers seem to really like a lot of air to breathe, and I found the sound of the #4 mod to be even better than the #3 mod. I think it also looks cooler as well!
- Drill a few 1/8" holes in the stock badge, in approximately the same locations as you see in the photo below. This is important, because there is a very specific 'gap' in the cup directly behind the badge that will allow you to grab the badge with pliers. If you drill in the wrong spots, you will miss this gap. I've indicated this in the photos below (ie where the yellow highlighter is). Also, drill only through the aluminum plate. Do NOT drill all the way through the plastic behind the plate, as you risk drilling into the driver! You will be able to feel when you are through the alumium plate (at which point immediately stop drilling).
- Now take pliers and pull off the badge. It's held on pretty strongly with glue around the edges, but keep trying and it will eventually pry off. You can also see the "gap" in the below 2 photos, which is basically a recessed "outer ring". It is this recessed area that gives the pliers the room to grab the aluminum badge.
- Now that you have the badge removed, you are going to remove the plastic material as indicated below. I used a cutting disc on my Dremel, and cleaned up the hole with a Dremel sanding drum. Be sure to leave a small amount of material (ie a "lip" or "ledge"), so that the grille has something to rest on. In other words, don't grind your hole flush all the way to the very edge. Go a few mms smaller, so there's a "ledge" for the grille to sit on. Make sense?
- Once your hole is ready, take your grille material (cut to fit perfectly into the hole where the badge was), and lay it down into the hole. The grille will rest on the "ledge" you left.
- The grille needs to be exactly 42mm diameter. You can buy 42mm grilles on ebay (for $2/pair) that will drop right in as a friction fit, and won't even need glue. Or you can buy a larger grille and cut it down to fit. I've seen the grilles in black, white, silver, chrome plated, or you can spray paint the grille any color you want before installing. On ebay or Aliexpress, just search for any of the follwing terms: 1" tweeter grille, 1" speaker dust grille, 42mm tweeter cover.
- If your grille requires it (for example isn't a friction fit), secure the grille with 3-4 strategic drops of clear epoxy or Lazer Bond UV glue. For example, 4 tiny drops at 12, 3, 6, and 9 o'clock, or 3 tiny drops arranged like a triangle (you can use the 3 triangle decorations on the stock cup as a guide of where to center the drops).
- Once the adhedsive is dry, blow all of the plastic chips and debris away using your breath, canned duster air, a brush, etc. It is critical that all debris is removed from the cups, to prevent any from getting inside of the driver. The inside of the bottom cup and the inside of the top cup (where the driver is) shoud be spotless before continuing.
- Once you are pleased with your results, remove the tape from the driver magnet.
- Put the cups back together, and replace the (4) screws.
- Put the earpads back on.
- Repeat the procedure on the other side.
Here's the final result:
