Good point. We could always have a meet here in Iceland. Those that have been in downtown Reykjavik at 6am on a Sunday morning know what I'm talking about...
Justin increased the price some time ago and the amps are in high demand so it should be a fair price. There is a new version of the amp coming but only Justin knows when that is.
I don't think I ever tried my 400's before shipping the transformers to Headamp... \ I did try them from a SRM-1 amp and not counting the channel imbalance I don't remember any power issues. I need to hook them up again...
When you look into the plug with the pins like this:
0
0 0 0
0 0
The top pin is left + and the left most pin in the middle row is right +. The bias for the left earpiece is in the middle of the middle row with the left - pin to the far right of that row. The bottom row is the right earpiece bias on the left and the right - on the right. There are pictures in my gallery here but a written explanation is always better.
Be very careful when removing the Stax socket as the break like an egg.
I ripped apart the adapter for my ECR-400 and they are indeed single ended or uni-pole electrets though the drivers are dipoles. When I wire up uni-poles I configure them just as a normal Stax headphone with the + side next to the ear and - to the back. This could be causing some issues but I think the air gap is much larger on the Sony then what the Stax boxes can deliver for.
According to the service manual the left pins are the two who make a vertical axis while the right side is horizontal. Polarity doesn't really matter.
It's the only reason that I'm a contributor on HF although having a search function that works can be nice as well.
Desoldering a resistor isn't that hard but don't do it you don't feel comfortable. If Deepak doesn't want the amp then I'll take it off your hands.
All has been quiet on the western front but I'm just waiting for the onslaught. It will come... it always has when Stax fever hits the boards. I'll probably be selling some more of my gear soon and I'm really not looking forward to that. \
The boards inside the SRD-7 are tiny or roughly 5"x2.5" but I can't be sure since I don't have any here. The PCB could be taller but not by much. Now if we were talking about a new design it's certainly doable wit some cheap transformers.
It's a basic PSU feeding a DC-DC high voltage converter. But like Marc said it's a trade secret...
It all fits on one of the perf boards you sent me with room to spare. It could certainly be squeezed into an energizer of some sorts with some creative thinking. I'm also going to build a combination supply around the small 230v/115v transformer with a doubler for the normal bias and 5 levels for the Pro.
I finished the variable bias supply destined for the BH earlier today and I was given the task to try out the Koss ESP950 at 620v bias. Holy crap is the first impression when listening to Megadeth out of a SRM-T1. The bass is much more controlled and so very deep that it gives the 4070 a run for it's money. The sound seemed a little bit forward as first but after some time I don't notice it any more. Now the bias supply should be able to reach 880v so should I see just how much bass they can produce.
The flash was probably from the fuse but the smoke is harder to pin down. Since you basically short circuited the transformer it could come from a number of components. If it works it works so no worries and listen to some tunes...
The Stax ribbon cable is the following for the 3 wires entering each housing:
Wire with stripe or dotted line is the +, the middle wire is the bias and the last wire is the -. If you look carefully at the plastic housing of the Gamma drivers you can see the markings for + and -.
The caps are the problem as 550v parts are rare and 600v+ electrolytic's are all but unheard of in the sizes needed. There is always the option of having them custom made but the cost...
I don't have any but who wants to settle for that supply when the BH deserves so much better. For comparison I'm going with a Sigma22 as the +/-15v psu so overkill is the name of the day...