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Posts by wakibaki

You should probably use 1.6mm for the PCB thickness, this is the most commonly encountered. I have thought about how to make all these parts, including spacers, from regular PCB thicknesses, because thin PCB is not easy to obtain in the UK. If concentric stepped rings are used in the supporting structure, this is comparatively easy to achieve with a CNC mill, even if skimming the PCB proves too difficult. w
So sorry to hear about your experiment gone wrong. Don't be depressed, it's a temporary setback. It is not uncommon to see resistors used in the amplifier circuit of Stax transformer drivers. This is intended to 'isolate' the amplifier from the transformer, these are frequently in the range of 2 ohms. The Ciuffoli design uses transformers with a quite substantial DCR. An 8 ohm speaker will typically exhibit a DCR < 6R5. We'd like to mimic the speaker as a load, I think,...
 Ah, OK. I was resigned to rebuilding them a few times. I'm trying to finish the HT supply. I went to the library today, to use the laser printer. My UV lightbox is playing up, I haven't figured out how to mill PCBs but I know I can do toner transfer with the regular paper in the library if I keep the tracks wide. Anyway I forgot to take a vernier. When I got home the printout was undersize. Grrr. w
A lathe is good, available quite cheap, produces nice results, but limited to round objects and requires skill if hand cutting. Making the same object twice by hand is not straightforward. Of course you can get CNC, but at added cost.   A CNC mill or router will produce irregular shaped objects in 2.5D or 3D with clever operation, but with a lot less dependence on skill. They tend to be a bit more expensive.   w
I wondered about the effect of coating both sides of the diaphragm, however I put this aside as I attempted the practicality of assembling my first pair of phones.   It's not easy perhaps to visualize the exact arrangements inside the electrostatic headphone capsule until on starts to construct one from scratch.   I discovered that, for me, the contact to the film sorts itself out like this:-   1. You take one spacer, coat the copper area carefully with an even film...
I'm used to using heat to shrink plastic film, the kinds used for covering airframes and wings of model aircraft. I used the heat gun a long way away from the mylar film to keep the temperature low and controllable. At first the film sagged, then tightened as I moved the heat closer VERY slowly. As soon as the wrinkles disappeared I removed the heat. I haven't been able to test the result yet tho. w
Why not make up a circuit board, or more than one if necessary, that will allow you to build a unity-gain buffer with each of these devices, then send a sample of music out of your soundcard, through the buffer, and record it back in through your soundcard. Then post the samples here without stating which is which opamp. Get people to vote for which they like best. w
I went to Malta for a week. I used to live there when I was 8~12 YO. Some things arrived by the time I got back:- These are the parts for the transformer-style amplifier I decided to take a flyer with. It's only ~8W into 8ohms, which is 8vrms, with a transformer ratio of 40, but I still think it should drive the phones. w
Yes, but not in this case, when it's only 75ohms. Amplifiers' input impedances are typically in the 1000s of ohms. When the output impedance starts to approach these values, then the output volume will fall. Since the amplifiers input impedance typically does not vary much with frequency, unlike phones, there should be no effect on the overall output quality except for the SNR, and no noticeable effect on that in this case.w
Some of the most productive engineers I have known had the most untidy desks. I work untidy, I can mostly lay my hands on anything. I think it's best not to try to adopt a working style that is not your own. w
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