Impendance Adapter

[sumguy_]

Hi, I am interested in building a 75-ohm impendance adapter/converter (a la the Etymotic P-S converter, but on a budget

)

While the soldering and so on I am ok with, I am not sure what type of resistors to use... What type is best suited to this job.

This is what i intend to do: I will buy an 3.5mm input jack and a 3.5mm output jack and solder resistors between the connections, except for the ground channel whcih I will simply interconnect with a simple wire.

Will this work? Thanks for your help.

Brian

 

[kramer5150]

I used 1/4 watt 2% metal film. (the small blue ones) I bought ~30 of em in a bulk pack. I use a DVM and measure the resistance of each one just to make sure theyre as close as possible.

I used used generic connectors from Frys, and soldered the resistors between the + lugs. For ground I used 2 segments of solid 22 awg copper, and soldered the grounds together at 4 places.

I used plastic epoxy and encased all the electronics in a cylinder shaped "blob". Used a file and dremel to shape it into a semi-round cylinder.

I have several adapters... 47, 75, 100, 150 and 200 ohms. My edcor HA400 likes ~250 ohm loads. While my AT HA2 likes ~150 ohm loads.
I'd post pics but I cant find my cam...

PM me with your address, and I'll send you 4 resistors. I have more than I know what to do with.

Garrett

 

[Syzygies]

I've made a number of these. The first several were with RadioShack hardware and metal film resistors and they sounded like hell. Now my PIMETA has no output resistance, but I have a short cable consisting of

Digi-Key CP-43502PM, CUI SJ-43502PM (Tangent's rec for a 3.5mm jack, great hardware)

Parts Express 092-157, Neutrik NYS231B gold 3.5mm stereo jack

eBay silver-coated copper stranded interconnect, teflon insulated

Mouser 71-RN55E-B-75, Vishay-Dale RN55E75R0BB14 75 ohm resistors

...and plenty of heat shrink. After a decent break-in interval, this sounds pretty good.

The Etymotic "official" cable costs $65. This isn't a total ripoff, there's a lesson here. One reads on the web about such cables DIY made with cheap parts. Not to offend anyone, but I suspect that some enthusiasts have tin ears; this is a very sensitive component to make for oneself. Don't phone this one in, make it with the above quality of parts or better.

My iPod lossless ripped from CD's, through silver coated copper interconnect and internal wiring, PIMETA with AD843's as op-amps, into 75 ohms and Ety 4p's, conspire to represent highs faithfully to a fault. I'm about to build an M³, waiting on PPAv2, in on the board group buy for Dynalo boards, so I can figure out what sound I like best. My hunch, to be honest, is that all discrete parts will sound most tube-like, everyone should get a few boards from the Dynalo group buy "just in case", and this rendition of highs veering toward brittle is the nature of the beast for op-amp based amps. PPAv2 is going to sound better because of the diamond buffers, I'll guess right now PPAv3 will be discrete. But what do I know, I only have two amps to compare so far...