May 5, 200818 yr I got a set Sony ECR-500 Electrets from Fungi recently and decided to have a play Insides of ECR. Stripped and cleaned. Getting ready to whittle Whittled! Testing for fit. Parts for assembly. Cable in and felt lining. All assembled. Last shot. Fun little project for the weekend and sounds great.
May 5, 200818 yr Can I have them back now? Just kidding, but I would love to hear those again some day. Did your super duper wood cup and foam replacement and recable mod make them better?
May 5, 200818 yr Author Mine, all mine.. mwahahaha! I won't know for a little bit what sonic changes there are as my Firestone 'Big Joe' isn't big enough and runs out of steam and distorts before it reaches normal listening levels. They need big-ass Hafler power to work well but that's at work in my office. At least it looks
May 5, 200818 yr Wow, really nice work. I'm sure if they sound as good as they look, you'll be a happy camper
May 5, 200818 yr Author Thanks all. They do sound nice and I'm listening to them now with the hafler. One problem though, the Stax transformers don't seem to have the windings/guts of the Sony. There's distortions going on in the lowest registers so I may need to go back to the Sony transformer with a Stax socket fitted. They are significantly different inside and the Stax box isn't doing it. More soldering tonight as I have a spare SRD-6 to steal a socket from Spritzer, do you know what 4 Stax Gamma plug pins correspond to the Sony plug pins so I don't wire it wrong? I don't have a test meter. For those uufamiliar with the ECR, here's a pic of unmodded ones. http://www.linaeum.com/images/sony_ecr500/ecr500_1_small.jpg
May 5, 200818 yr Thanks all. They do sound nice and I'm listening to them now with the hafler. One problem though, the Stax transformers don't seem to have the windings/guts of the Sony. There's distortions going on in the lowest registers so I may need to go back to the Sony transformer with a Stax socket fitted. They are significantly different inside and the Stax box isn't doing it. More soldering tonight as I have a spare SRD-6 to steal a socket from Spritzer, do you know what 4 Stax Gamma plug pins correspond to the Sony plug pins so I don't wire it wrong? I don't have a test meter. 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.
May 5, 200818 yr Author Yeah, The sony needs way more juice than the Stax box can deliver. I did wire the + earside, I don't know which of the Stax 6 pins are the + and -. I'm assuming the middle and top pis are bias, is that right? I'll probably bypass the speaker switch too to keep the signal path simple and clean while I'm in there.
May 5, 200818 yr 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.
May 5, 200818 yr Author Thanks Birgir, They sound great as-is, so long as there isn't huge bass going on which many of my records have, then it farts and gives up unless you turn it down, then the bass comes back out. They play merry havoc with weak amps and Stax transfos. They are far and away the biggest pig to drive of anything I've owned. No weedy amps for these bad boys
May 5, 200818 yr Thanks Birgir, They sound great as-is, so long as there isn't huge bass going on which many of my records have, then it farts and gives up unless you turn it down, then the bass comes back out. They play merry havoc with weak amps and Stax transfos. They are far and away the biggest pig to drive of anything I've owned. No weedy amps for these bad boys 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...
May 6, 200818 yr Author I did some more surgery tonight and stripped out all the excess switch crap from the Sony transformer, replaced the input wire and took the easy way out connection-wise by just welding some banana sockets to the outputs and bananas on the headphone cable. Simple but effective. Going to make a nice box for the transfo seeing as I have to look at it. The Sony transformers look about 50% bigger than the Stax ones. After re-attaching it the bass was back. So it seems they definitely do something different. On top of that, the mods have recovered that recessed treble and they sound much better balanced overall and closer to the Staxe highs with more bass while retaining that sweet mid section. I'm very pleased so far.
May 6, 200818 yr It could very well be that the Stax boxes were starving them of power which would account for the anomalies at the HF and LF.
May 6, 200818 yr If they are unipolar elements like the pictures sure show them to be, then the bias has to be added to the audio signal. No bias and they sound like shit. A stax transformer box without modifications cannot add the bias this way.
May 6, 200818 yr If they are unipolar elements like the pictures sure show them to be, then the bias has to be added to the audio signal. No bias and they sound like shit. A stax transformer box without modifications cannot add the bias this way. They are driven as uni-polars but are really just normal, push-pull drivers with two stators on either side of the pentagonal electret film. The schematic for the adapter shows just a simple input to the transformer and output again. I just noticed that Sony had included the impedance specs for the transformers 3?:4100? which works out to a step up ratio of 1:36.97 The other uni-polars I've owned had a single stator and a metal backing plate connected to ground. That's what Phillips uses at least.
May 6, 200818 yr Author The Sony transformer is really simple inside and only has two bridging components per channel aside from the transformers.
May 6, 200818 yr Author No chuck. It's a disk of rock maple screwed to the lathe block and I mount my working wood with turners tape so I can cut right through it The drill holes in the blanks and mount are so I can center the blanks easily.
May 6, 200818 yr Really nice job on the cups. Is this the lathe you just bought, or am I thinking of someone else who just bought a new latheh?
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