[headchange4u]

I have ordered several different brands of 68-75 ohm resistors that I am going to test for their sonic differences in the application of a 75ohm conversion cable.

I would like to etch my own PCB test board. I just need help in the layout of the PCB.

I will be using Switchcraft PCB mount jacks that my headohones will plug into and that will go into a Neutrik 3.5mm plug that I will mod to fit on the board. I also have some sockets that I am going to use for the testing of the resistors. The socket solder into the board and they have an open top that will accept the lead of the resistor. This way I will not have to solder a test resistor into the board and then desolder it to get it back out. I had also thought about using one of the sockect used for mounting an OP amp. This much I can figure out on my own. It's pretty simple design.

I have now decided that I would like to incorporate a seletor switch, preferably something I can pick up at Radio Shack. I would also like to mount some Vishay resistors to the board, which is what I normally use in my conversion cables. The selector switch would be used to switch the signal between the test resistor and the "stock" Vishay resistor for a really quick A/B comparison with out having to plug and unplug a cable. One reason that I want to do all of this on a test board is because I don't want any cabling in the equation to color the sound I am getting throught the resistors.

I hope this makes sense and someone here could help me.

 

[jerb]

well You sould try to find a higher quality switch, one from radioshack wont help much becasue you'll be running the signal through their switch so it wont reviel much about the ressitors. I would recommend A higher quality attenuator and just put the ressistors to test into it.

if you used an attenuator you could put all the ressistors in it and select which to send the signal through by rotating the knowb, Should be a very simple thing to do on breadboard

 

[headchange4u]

Wouldn't using a attenuator require me to solder the the resistor in? I'm trying to avoid this because I want to reuse the resistors and I don't want to go to the trouble of desoldering them after testing. Also, aren't attenuators a little expensive? I mean even if the Radio Shack switch effects the sound, it would effect both the test and "stock" resistors.

If someone has a better method for performing this test, I'm open to ideas. I still would like to be able to A/B the resistors on the fly without having to switch stuff out.

Thanks

 

[headchange4u]

^^^

Anyone?

 

[Sinbios]

I hacked up this with PCBExpress, but I'm not sure what kind of switch you want to use.

 

[headchange4u]

Quote:

Originally Posted by Sinbios I hacked up this with PCBExpress, but I'm not sure what kind of switch you want to use.

Thanks for the file. That's a what sorta wwhat I am looking for and helps me get on the right track.

I am assuming I will need a 6 pole selector switch.

I guess I could use a 4 pole and run the ground straight from the jack to the plug and then use the switch to toggle between the signal channels. Does anyone see a problem doing this?

EDIT:
I've also been playing around with PCBExpress. If I can find the part number of the PCB mount 3.5mm jack I am using, how do I go about importing the layout of that particular component into PCBExpress?

 

[dsavitsk]

how about soldering one end of each resistor together and using an alligator clip to switch between the other ends? For the money you'll save on making a PCB, using sockets, and using an expensive switch, you can buy a second set of resistors. Further, and sound degredation caused by the clip will be equal across all resistors. You can also use a piece of RS protoboard with a long trace to allow easy addition of additioal resistors.

 

[Sinbios]

Quote:

Originally Posted by headchange4u Thanks for the file. That's a what sorta wwhat I am looking for and helps me get on the right track. I am assuming I will need a 6 pole selector switch. I guess I could use a 4 pole and run the ground straight from the jack to the plug and then use the switch to toggle between the signal channels. Does anyone see a problem doing this?

The grounds can go straight through, yes. You'll still need 6 poles, two for each set of resistors, and two for output.
Quote:

EDIT: I've also been playing around with PCBExpress. If I can find the part number of the PCB mount 3.5mm jack I am using, how do I go about importing the layout of that particular component into PCBExpress?

It's easier just to measure the spacing on the jack, and put in pads.

 

[headchange4u]

Thanks for the help. I guess my next task is to check Radio shack and see if they have a switch to fit my criteria. I will post my layout when I get it finished so I can make sure it's done correctly.