Orthodynamic Roundup - Page 916

did you guys notice that Dual DK 720 that list on the auction for $335.43 or best offer ???

I saw it, and it's insane. The Dual is nice enough for the 40 euro I paid for mine, but it needs new pads, the cable has that inline volume control that might not be desired by audio purists, and it might need other damping modficiations too depending on your taste. But it might be part of the usual PMB driver lottery, that you never know what driver you are going to get. Maybe the fun of the lottery isn't worth 335 usd...

I've been doing more experiments with T50s trying to get the most I can from them. It's come down to a fairly basic setup after a *lot* of tests, trials, tribbleations and a few $1,000's of dollars in materials and tools. I'm posting this so if anyone wants to try it for themselves, it will act as a guide of sorts to get you started.

This is the basic look in and out. It's almost as basic as you see here with a couple of other bits not shown. Dense hardwood for the cups. 1/4" UHMW polyethylene for the baffle, rubber glue (Goop) to hold the driver to the baffle and a semi-dense felt pad on the rear of the driver, stuck down at 9 points with hot glue leaving a cutout for the baffle vent hole.

The bits not shown are foam gaskets. One between cup and baffle 1mm thick and one between baffle and pad at 2mm thick. This is the black craft foam sheet usually used to cut shapes out. These are just put in place and screwed through.

Anyway, enough talk...



Inside of the cup is lined with stick on velvet. The driver/baffle is cut down and glued to the roughed up UHMW baffle. UHMW is extremely low friction and difficult to get things to stick to it so I roughed it up with sandpaper. The goopy stuff on the side of the driver is hot glue securing the wires, the solder pads are easily pulled off the flexible circuit board if you tug the wires too hard. You can see the baffle vent in the red felt cutout. It's a hole all the way through the driver frame.




The front of the baffle. Luckily UHMW is easy to cut and turn on the lathe. 4 #4 brass screws hold the baffle down. The foam gasket is in the small gap you see between the cup and baffle. I just drew around the baffle and cut the gaskets out with scissors similar to how loudspeakers are mounted. The baffle is dished for extra comfort and room. The baffle vent is also visible in the dish. You can block this with tape or a small screw for more bass.



Cups with O2 pads and shelf brackets in place. The stock fostex pads will also fit and are pretty comfy with the dish. The cups are slightly smaller than the baffle diameter so the pads have a lip to sit over. The small brass fittings for the bass ports at the bottom of the cups are from a hobby shop. Something to do with RC cars The wood in this case is Katalox. One of those woods that's very hard, heavy and sinks in water.

As you can see, the internal damping is extremely basic. The wood and UHMW both absorb energy very well and the mass lets the drivers do their thing.

So there you go. If anyone else wants to try this scheme, the cups are 4" dia. The inside cup cut-out is 3-1/4" dia and about 1/2" deep. You can do this with a 4-1/8" hole-saw and a forstner bit rather than lathe so it's doable with fairly basic tools. The baffle dishing can be done with a 2" sanding disk and a 50-60 grit pad, all available at lowes/Home depot etc.

Felt can be used in place of the velvet and you can pick up the felt, foam and screws at any number of hardware and craft/art places. The baffle is UHMW because it's the best stuff I've come across for this but other stuff like wood/mdf will work too.

Hope it's of some use to someone

Edited by smeggy - 7/14/10 at 11:41am

Thanks Smeggy, that's fantastically useful! Fantastic!

The masters guide --- fantastic smeggy!!

..dB

Smegster...master craftsman, you just make it seem so easy

X2

Ack!! I mean, thanks

hehe

It's all done over a series of days... it might look easy but it's a lot of stuff to do, especially to do right and not make a total dogs dinner of it. I'm still working on that bit. I think I've finally hit the plateau with the T50 where I'm not sure I can make them sound any better, and even these wont be to everyones taste. For me, this seems as good as I can get them... for now

I think flame burled Madrone makes them better.

Did you try any of the Oz felt in them or where you already out of it? It's pure magic on the T10s, T20s, and RP18s, so I wonder and hope it would be a synergistic match with the T50RPs too.

Then you just have to see which cable sounds the best. I might try my Soloz Audio Hybrid silver/copper cable on them after I'm familiar with their sound using the Alpha SPC. Then decide if the sound quality improves or the sound sig changes are worth the extra $300 expense and giving up that awesome braided, heat-shrink free Alpha cable.

talking about cabling..after having a chat with Don about this offline and my recent brush with nearly blowing up the EHHA..again, sersiouly considering moving to mini-XLRs for the headphones and amplifiers in my builds.

Anyone got any views on this?

Mouser has the new Neutrik mini-XLR plugs and jacks..

Neutrik TINY XLR

fantastic guide .......

thanks Smeggy.

The flames will be nice, and now I can incorporate the latest mod tweaks. They don't need much in the way of felt or damping as they don't start out nearly as dull as the older phones but I still have a small bit left to try.

As for swapping cables around.. I don't really have a way to make this easy. I'll have to ponder.

They look pretty good and I might give them a try with something like a flying TRS adapter for not so picky amps. Wonder how big they are in the flesh.

Thankee

So does this mean it is not possible or I may risk damaging my Fostex "thunderpants" if I were to recable them?

The panel mount is almost a near fit to the Neutrik 1/4 panel jacks that I use, the cable mount plugs are supposed to be about the same size as the 1/4 inch jack

No, it's entirely possible. Just not necessarily easy as I tend to glue the cables to the housing so they're well secured. Just go carefully. I guess as I'm not a cable believer I don't really consider it.

Excuse my first post. I guess you can install one of those small connectors that HE-5s use? They look like MCX connectors, have a look on digikey. They are expensive though, I wonder how much its costing head-direct for giving an extra pair for everyone. @_@