Good evening ortho lovers. I need some inspiration on the future project. Basically not an ortho transplant but rather whole new headphones. So here it goes.
Most important: the drivers. I am planning to go for Amfiton TDS-7 - the soviet flagship isodynamic headphones. Impedance is 8 Ohm. 1 Watt max input power. Very difficult to drive for mainstream headphone amplifiers. However people reported great results when connecting to speaker power amplifier terminals, most of which are intended for 4 or 8 Ohm load, not very convenient though. Then I thought, wait a minute last technologies gave us small and efficient class D amplifiers. They are small and also sound good. Also there is a boom of small class-D boards with low voltage supply and power of around 1-15Watt.
Here are just a couple of class-d amplifiers with 1Watt (THD under 0.15%) output power into 8 Ohm load, with digital volume control (don't even need volume pot) and 5V supply. You can use a 5v usb AC adapter or maybe PC usb port, maybe even regulated 5V linear supply that can be overkill for class-D amplifiers.
These would be just awesome to drive these vintage orthodynamics with pride.
Little bit about TDS-7. Many info in Russian language, and most people claim that their full potential opens up with open back construction with proper damping. Some guys took measurements that looked ruler flat from 20Hz to 1Khz and very good extension to 20Khz without big dips or peaks. After modification some preferred them to LCD-2 and HE-500, they are that good.
Now about the driver. The size of square membrane is 4,5 x 5,5 cm or 1.8 x 2.2 inch, a very big surface. The cups that hold membrane with magnets together are 6,5 x 7,5 cm or 2,6 x 3 inch.
Ok, now is the time to think of a good donor. I need super comfort, and super isolation, big assortment of accessories and solid build quality. Heck is this even possible?! Yes. Few moths ago stumbled upon David Clark headset for pilots and aviation purpose. Read a lot of reviews on these and realized that this is perfect for transplant, as it totally matches above criterias. You can buy these headset from many shops online or ebay. Also a wide variety of cords, ear cushions, headbands etc. available.
The model H10-76 seems very good with many positive reviews about their great comfort for long travels and massive isolation needed in noisy air crafts. Also cup size is little bigger then needed for TDS-7 drivers.
Now how about a very important aspect of headphones, the ear pads. I found very nice David Clark silicone gel filled ear seals also with many good reviews about even greater isolation than stock pads on this headset. They are deep and big and rest on head, but not on the ear.
About construction and elaboration of this project I don't know. This idea is only on the paper so to say. Of course there will be definitely open construction. Need of cutting down the cups to accept the driver. Maybe some sort of grill on the outer side just for pretty design. There are plenty of damping instructions on orthodynamics both in english and russian. Also a simple electret microphone for measurements as well as some headphones for reference with existing measured frequency response (like on InnerFidelity or headroom or Purrin(from CSD thread)).
Constructive criticism and new ideas or suggestions are most welcome!
Edited by TiEx - 11/7/12 at 10:33am