KODA^2 - The revised model (KODA^1 is farther down this post)
THIS IS NOT A SALES THREAD - THIS IS STRICTLY ABOUT THE PROJECT, SUGGESTIONS AND COMMENTS. PLEASE RESPECT THAT AND DON'T ASK ABOUT PRICES AND ETC. IN THIS THREAD. THANKS...
Let's start with showing the final KODA^2 headphones
MACASSAR EBONY + Bee Wax - KODA^2 Matte polished acrylic with walnut burr and bee wax - my own headphones
MACASSAR EBONY + Bee Wax - KODA^2
Walnut Burr + Varnish - KODA^2
The KODA^2 – Optimizing the prototype
Since I made the prototype – I have done some optimizing of the design. It still looks the same on the outsize – but inside has been optimized with the correct sized bass port and 20% less material in overall. This makes them lighter and gives them just the right bass port directly from the laser cutting process. I feel that the weight of the KODA^1 is their only real downside and the new optimized design should issue this and make them below the acceptable 500 grams. There was so many things that needed a bit of grinding in the prototype on the inside to fit the drivers and it has all been corrected on the KODA^2, making it a better and more polished product while including the almost countless optimizing I did on the prototype J (OK – not countless, but quite a few I assure you).
Status of the KODA^2 headphones
I will be making four KODA^2 headphones - one of them will be for testing and reviewing and will be shipped to Tyll at Innerfidelity asap.
The changes from KODA^1 to KODA^2 is:
1. Nicer veneer - I will let you choose between a couple of types like walnut burr or zebrano
2. Nice thick black felt on the inside of the headband - very discrete
3. Minor tweaks and optimization to the inside dampening
4. Bass port micro-tuned for even bette balance
5. Less reflective, matte finish on earside of baffle
6. About 20% lighter
7. Reflective felt spot behind on back of cup
08 December 2011
I got all the parts and I have started making the first 4 units. Here is a picture:
This is only for two sets - I am making 4 headphones in this round.
Walnut burr, Australian Walnut and Macassar Ebony (no varnish yet)
09 December 2011
New and very improved baffle, unbelievable stiff and it's matte polished.
Australien Walnut - first finished cups.
Matte polished with veneer almost completely polished away for a burned look. Then it is treated with bee wax. The polishing of the parts is a tiresome process and I have used almost 6 hours doing so.
I really love the look of the matte polished acrylics with bee wax. It feels fantastic too.
09 December 2011
Much smaller ball joints - I had to do some drilling to get the aluminium rods to fit. The result is a much lower weight and nicer and more balanced look.
Baffles with the T50rp driver and flet hole damping. Notice the silicone gaskets.
11 December 2011
The finished cups - the 4th one in ebony isn't finished. The ones in the middle is with Australien walnut veneer. The matte one is my own and the nearest one is for reviewing and testing. It's going to be sent to Tyll in just three days.
12 December 2011
The last cups is finished - It's the second from left, ebony.
Internal dampening felt. The nuts will be covered with a reflex dot made in hard felt
Reflex dots. The felt with hole over the driver makes sure the bass is deep and the reflex dot lifts the treble a notch.
My hearing says it's working beautifully - guess it's soon time for sending a sample to Tyll for testing to see if it is so.
Closing the first cup - embedded screws and matte rough surface.
Finally the first finished KODA^2 - IMHO it's much nicer looking than the prototype and almost 100 grams lighter.
Very nice wiring, Neutrik plug and they are so comfortable.
Australian Walnut veneer
Ear side of cup (Australian walnut veneer cans)
I'll get back tomorrow with some better pictures (this is from my mobile) and sound impressions - but I can reveal that the bass and treble is extended even farther with the small optimizations. Very positive initial impressions I must say!
KODA^1 - The Prototype model
I have been following these forums for a long time - even without being a member until now.
I have been particularity interested in the ’Orthodynamic’ Roundup thread – and that got me interested in the T50RP threads. I knew right away that the T50RP driver was just what I needed for my custom headphone project. A driver capable of delivering an extraordinary detailed midrange – with potential for delivering a fast and tight oomph in the bass region while maintaining detailed highs, without emphasizing them too much.
About the material
Having worked quite a lot with PMMA or acrylics in the past – I know this material is dead silent when bonded with solvent and build up in multiple layers. A construction of this feels and sounds more like a solid block of granite or marble than a plastic material. It’s a bit like a solid block of aluminum – but it weighs much less. It can be cut with laser, making it easy to make completely identical parts unlike with wood. Is it better than hardwood? No – it is different, with different sound characteristics and a much different esthetics and possibilities in design. IMHO It is more comparable with aluminum than wood concerning sound signature.
There are some downsides to acrylics compared to hardwood though. It is not as light weight. It is much more expensive in raw material and even more so to process. It requires much skill to work with and most errors cannot be corrected, meaning you have to start over. Not a beginner’s project.
The actual construction
The headphone cups are build up in 6 layers of black acrylics, 5 of these are bonded with a solvent making it more or less one piece of solid acrylic. On layer has the hole for the wiring and one has the bass port. The last one is the baffle and it is mounted with six screws to the rest of the cup, with a silicone gasket in between to make a completely airtight seal. The T50RP driver is mounted with the the three original screws and also has a silicone gasket to make another airtight seal. The small hole through the driver is extended through the baffle and the gasket.
The outer layer of the cup is covered with real wood veneer – purely for the esthetics. The veneer is bonded with epoxy and weight pressed while hardening.
I kept the T50rp headband and used dual angled ball joints for connection between the cups and the headband. This makes the cups very flexible and secures a perfect fit. The joints are fastened to the cups with 6 mm bolts and nuts. This will probably last a nuclear war – but I like the look and I would like to avoid any visible screws.
I found that my original bass port size needed a lot of tweaking to hit the exact sport where the oomph was deep while remaining tight, fast and well controlled. After changing the size with various tubes about 20 times – I found just the right size.
The cups has been dampened over and over again until I found just the right well balanced sound signature, with just a tad to the warm side. The driver ended up being stripped of the mesh on the ear side and fiberglass of the cup side, making the highs shine even more with a beautiful vivid soundstage. I found the hard craft felt to be terrible harsh to the ears in the high notes, so after a lot of experimentation with materials of different sorts, I ended up with 3 mm 100% wool felt, with a square hole in the middle. The square hole extends the bass and soundstage and makes driver “breathe” better. Without it, the sound is a bit muffled up. The back side of the cups was covered with 3 mm felt, but I found that felt with holes made for at bit bigger cup and a bit more airy sound. The treble was extended a bit by using craft felt behind the holes. And finally I was satisfied with the sound signature.
I found the original T50rp pads to be pretty disappointing. So I planned to use the widely available and not too expensive Shure SRH840 pads. They are much more comfortable makes for a better seal. I would like to try the Shure SRH940 velour pads sometime in the future. The cups are actually designed to make a perfect fit with both Shure pads.
I started with buying some very expensive Vandamme cables – but they were not nearly as flexible as I wanted them to be. So I ended up using some good quality thin OFC loudspeaker cable that I weaved into a nice and very flexible cable. They actually sounded better than the Vandamme cable with better low frequencies. I really like the new cables and I think they match the sowings on the Shure pads very nicely.
How’s the sound?
The headphones was tested with a modded Lovely Cube amp connected to a Xonar D1. Flac files used.
Compared to the original T50RP – they are just so much better that you would never expect them to have the same driver. It’s really mind boggling to even think the thought.
Compared to the T50rp with different mods and dampening approaches, plasticine, craft felt and different variations of covering the bass port – I think the KODA^1 is much more well balanced, and has a deeper and tighter bass response while having beautiful heights and the insanely detailed / fine mids. I think the step from the original T50rp to the dampened/modded T50rp is huge, but I find the step from the modded T50rp to the KODA^1 mod even as big if not bigger. Remember that this is just my opinion though.
The noise isolation is extremely good – and that wasn’t really surprising giving the nature of the acrylics. It’s on par with different industrial hearing protection I have tried, but this wasn’t something of a concern in the first place. The closed design has some disadvantages too, compared to open designs as you probably know.
I actually think there headphones sound much better than the AKG-701 with a lot more oomph and less harsh heights. I tend to find more detail in the mids as well. Overall I would say they are more well balanced. The KODA^1 is a closed design, but IMO the soundstage is just as good as the K-701 and they are a lot less fatiguing to listen to. When comparing the two – the K-701 ends up sounding shallow and somewhat artificial in comparison.
I feel that the bass response is close to beeing as deep as the HD 650 – but it is also so much more tight and so much faster. The mids is more comparable to the K-701, than the HD 650. Best of both worlds actually, while being better on almost all areas IMO. The KODA^1 has a crispness and ‘slam’ to them that I just haven’t heard before. I really think KODA^1 is in another league. I would really like to compare it to HD 800 or LCD2 instead – that would be very fun.
Update 30th November 2011
I just tested the KODA^1 with a very basic hybrid tube amp today - I boy am I impressed. It's the cheap Bravo tube amp with the 6922 tube. While the stereo separation and the detailing in the highs is nothing compared to the Lovely Cube, it has the sweetest, most well rounded mids combined with deep deep killer bass and plentiful power. I am really impressed. Makes me wonder if a hybrid tube amp is the holy grail of the t50rp driver. Makes me wanna test it with a better hybrid tube amp. This headphone seems to have unlimited potential at the moment - only limited by the equipment so far.
I would like to thank all contributors to the different T50RP thread and to the Orthodynamics Roundup for inspiration on different dampening schemes. I found a lot inspiration from it and I used what I found to work. I would also like to thank Smeggy – the creator of the Thunderpants for inspiring me to use a bass port design and giving me a rough idea of the cup size. While I don’t think my project is a replica of the Thunderpants – I still feel I borrowed bits and pieces of his experience with the Thunderpants nonetheless.
I hope this post isn't offensive to anyone, as it is my first post on Head-fi.org. - Cheers!
Edited by lokesen - 12/16/11 at 5:50am