[Don Quichotte]

Hi! I just bought a Cambridge CD player that's burning in right now. I will post some impressions in a few days. I need to build a kind of a passive preamp and I would really apreciate some advice regarding the stereo potentiometer (I know Alps are good, but which one to buy and from where? I don't even know what characteristics to look for...) and the IC / jacks. The budget is about $ 40 in total. The IC can be really short, and I would see it directly soldered inside the pre.
This pre will be used for two applications:
- lowering the sound level when listening to my K501 directly from the RCA outputs of the player (don't scream, no money for a Gilmore right now and believe me, Jazz and others, it's more than listenable). So I need an appropriate headphone jack too, beside the normal RCAs.
- driving the Mackie HR 824 active monitors I am going to buy next fall.
Questions (excuse me for their stupidity, but I am a total newbie in DYI):
- what to buy and from where?
- can I / is it better to use interconnect cable for the internal wiring? If yes, where can I buy at lengh? If not, what is normally used?
It's important not to have the highs or medium - high bass diminished as a result of this application and, also, not to lose detail. It's OK to sound neutral or a bit cold.
Thanks a lot!

 

[Sovkiller]

Alps Blue Velvet, is the most common to use, around here, it runs about 15.00 more or less, other could be the Nobel (black and big) instead of Alps (some prefer it), or an stepped attenuator, maybe (this will be real expensive)....

 

[Wodgy]

I wouldn't recommend an Alps Blue for this application. What you're looking for is a very low impedance stereo potentiometer, and I don't believe Alps pots are made any lower than 10kOhm. Ideally, you should look for something under 2kOhm. JaZZ uses a 500 Ohm pot, but he may have lucked out in finding that. Certainly that's around the value you should be looking for.

If you use a high-impedance pot (10kOhm or higher), you have three problems: 1) you risk picking up a lot of noise, 2) the highs will be rolled off if the interconnect between the pot and the speakers is of medium or longer length, 3) you'll get loose bass. Also, be sure the mount the pot in a metal case, with the chassis grounded, to minimize the risk of noise.

You'll also want to use shielded interconnects. (If you want to have some fun though, build a quick-and-dirty pair of unshielded interconnects and try them between your passive box and the powered speakers. You'll get an unbelievable amount of noise pickup. I know this because I've been there -- this experiment convinced me of the necessity of well-shielded interconnects.)

 

[Sovkiller]

Maybe something like this one (sorry I missed that part that said that is for a passive pre, but anyway I do not think they made this one is less than 50K, you have to find out, but this one is used as a "passive pre"):

 

[Don Quichotte]

Fast and informative replies - isn't Head-Fi a great virtual place to spend your virtual time?! Thanks!
That stepped one looks beefy, Sovkiller, too expensive for me.
What other brands of potentiometers should I look into if we exclude the Alps because of too high impedance? A few more names would be helpful.
Also, regarding the interconnects, are there any decent priced ones shielded? Listening more to the CD player (too warm and polite) I reached the conclusion that the interconnects should be fast, with proeminent transients and especially with an elevated upper octave (and ideally upper bass). Don't say silver, not enough money! Can I use Belden mic cable or something like this? The Mackie guys recommend it, but they do not reffer to a passive pre. I will not have the chance to listen, I can rely solely on your suggestions...

 

[agile_one]

I know you were looking for parts for a DIY project, but if you change your mind, here is an absolutely mind blowing performer:

AXIOM Passive Controller

Tim Stinson will tailor it specifically for your components, and you will be very happy.

Highly recommended.