Roll Call: Who's building, built, or thinking of building a beta22? - Page 15

any 4 conductor cable should work though? gauge doesnt need to be too big im guessing by the fact that the secondaries are probably only about 24 or so themselves?

The secondaries are quite 24ga, but I'd still go with a larger wire for the umbilical cord. It certainly doesn't need to be huge but I wouldn't use something like starquad or mic cable either. I believe there are some tips given on amb's site about this stuff.

yea there are, its specifically with regards to setting up the s22 in the separate enclosure as well, and it says 18AWG minimum, i figured since thats not exactly what ill be doing, id still be better off going with something around 20 or 22. ill look into powercables online, we have terrible local selection around here as its just a tiny university town!

anyone know of good places to order small enclosures? im not too picky, but something with a removable front/back panel would be the best as im planning on probably just sending a whack of stuff to FPE to get done due to my lack of equipment. i know the hammond 14 series could be a serious option....

Damn straight skippy! i might not be so good at it if I hadn't made so many soldering errors though

How about Hammond cases...pretty cheap and ready to go from Digi-key or Mouser. They come in black as well.

AMB has some multi-pole connectors listed on the Sigma 11 parts lists I think.

http://dkc3.digikey.com/PDF/C071/0320.pdf

I fit the S22 in to the case supplied by Jeff Rossel for the S22 in the S22 kit. It took a bit of manouvering and some work with a dremel, but it got done.

Does anyone have a relatively inexpensive source for a quad stepped attenuator kit? As in less that $100? Or should I just go for the quad Alps from the german ebay site?

I don't think that cheap and quad stepped attenuator belong in the same sentence. FWIW I've never seen a kit for a quad, only preassembled bits.

Re: replacing the diodes

Since these are two-pin devices with relatively good sized pins, it shouldn't be too difficult to remove, but you need to heat the two pins simultaneously (or nearly so) after getting rid of most of the solder around the joint (either with braid or desoldering pump), at the same time gently pulling the diode away from the board (with needle nose pliers).

Once removed, the holes may still be plugged with solder, but the heat-and-stick procedure that Nate described is doable. You could also try to clear the hole by heating it and then plunging it quickly with a thin wire.

One thing to avoid is to heat any pad for too long, which could cause the pad to come off the board. If you use a desoldering braid you have to take extra care not to heat things for a long time. If you have a flux pen, you might find that applying some flux would help the solder to flow.

Just be glad you aren't doing this to a device with many pins (think OPA541AP on the Dynahi PSU)...

Thats a bummer I thought I remembered seeing some cheap kit with a switch and resistor pack, but I suppose it must have been a dual one. Have you used the Alps quad pot? Any problems with quality?

When using a braid, it sometimes helps to apply more solder, especially if it's plugged in a hole. Fill the pad, then use a clean section of braid that is still soft. Braids are flux infused, so once it's melted it's really not good anymore unless it's just a lump of solder you need to remove. The solder will come out quick. The trick is getting it to flow into the braid first, which is what filling the pad does, and being in liquid form, solder follows the flow, once the flow begins (surface tension and fluid dynamics mumbo jumbo). Sometimes more is less, as opposed to less is more. It'll be much faster than trying to heat the braid and get a section of it into a through hole.

I don't know if it's recommended for the case being discussed, but you can make a solder bridge and pull out the diode quickly. If you don't want a solder bridge you can build up the solder on the underside so that it's nice and tall, and stick a diode leg or a few resistor legs between the pads (elevated from the board), shorting out the component. Then heat the legs in the middle, and it should melt both pads simultaneously.

I'd prefer to just cut it, and remove a pin at a time, unless there's some reason you need to keep the diode functional. Diodes are thicker than resistors, so it should be fairly easy to get a snipper in there and cut out the diode.

Another possible suggestion is to get some thin bare metal wire, like used for picture hanging, etc. Loop it around one leg of the component. Heat the pad from the under side and then yank the wire. I've never known a component to be completely rigid and the component will bend on the leg that's still soldered down, pulling the heated leg up.

The wire trick is used, sometimes, for surface mount components (QFN), but instead of pulling up, you pull outward to get a slight gap between the pads and the component.

You were probably thinking of DIY Fidelity's kit, which is a dual stepper. However, if you've got room you could always use 2.

I've got one, but haven't used it yet. And I can't imaging quality being a big issue, this is what Headroom uses in their balanced desktop.

I think this will probably be the best way to go then.

yea ive got one and thats what im planning to use for now, i might go to stepped attens later. ive still never REAAALLY fully understood why stepped attenuators are so much more high end and expensive than a potentiometer. is having the "steps" really that helpful, in remembering exactly where you like it set etc? or is it a higher "quality" way to alter the amount of volume, by increasing the resistance?

A good article:

http://tangentsoft.net/audio/atten.html

Another choice is the Twisted Pear Audio Joshua Tree logarithmic stepped attenuator. That's the way I chose to go, and will comment on it once I receive my finished β22. The Joshua Tree balanced kit is $133.00, much less than some high end steppers. Luvdunhill says he likes it better than the Single Power stepper.

Nate have you used one yet?