what value pot for DIY volume control?

[Tom Mobley]

I've got a TEAC digital amp coming, also have Sony 333ES CD-SACD player. Something tells me it going to be a little on the loud side through Khorns with no attenuation. I'm building a small volume control, basically four RCA jacks and stereo pot. Question is, what value for the pot? Seems like 50K, 100K, 250K and 500K ane the usual suspects, but which one to start? I'd rather err on the side of too quiet rather than too loud to begin with, don't want to freak the wife and all that.....

[minn_male42]

use a 10k pot with an audio taper....

[sfogg]

Tom,

Any will actually work. Typically though it would be anywhere from 10 to 100k.

Doesn't really matter if it is an audio or linear pot. You might actually prefer a linear pot.

Shawn

[mikebse2a3]

My Creek OBH-10 uses a 50K control

I also have a DIY passive volume control using Nobel dual(stereo) 50K controls one for left and right channels. This way I could wire it as a 25K(wired in parallel)or use just one section for 50K. When I used it with a tube CAL D/A converter the 50K sounded best. A lot of tube equipment would probably work best with a higher impedance load like 50K and up.

mike

[Tom Mobley]

Thanks, guys. sounds good. question: the TEAC is a 3 channel amp, got any ideas how to make my two-bit attenuator grow a third channel output? I have Khorns with center Belle, right now I have an HF-81 with the center wired across the 4-ohm positive taps. Works OK, but somehow I'm doubting the TEAC will be happy wired up that way. Although, my '60 Khorns are labeled as 16 ohms. Any bright ideas on deriving a center channel?

Sheesh, does any body even know if it needs 3 inputs? Maybe it's getting the third output internally?

[3dzapper]

Tom, The Teac has three discrete inputs and three pots in the rear. Build yourself a PWK box with jsut the resistor bridge as you already have the level pots required. Then if you want to get fancy, use a pair of 100K Ohm alps pots available on eBay for $19.95/pr You could gang one for L/R and use 1/2 of the other for center or just use 1/2 of each for L/R and set the center level using the pot in the Teac.

I'll show you mine....

All 22K Ohm 5% resistors.

Rick

[Tom Mobley]

Rick,

That PWK box is confusing to me. In the original in DfH I see two resistors, in yours there seems to be a few extra? Also, the three connectors on the back, is the center one for both grounds? I don't see any pot in yours, is that because it was built strictly for the teac that already has pots?

'course, I had to take a couple percoset today after getting the cast off my leg, so I might just be stupid.

[Daddy Dee]

Tom,

If you get the Teac before you get the attenuator built, it does have a pot for each of the three channels on the rear of the unit. Not especially convenient, but workable.

[3dzapper]

High Tom? No there are a total of seven 22K resistors in there. In PWK's drawing he uses 25K pots for two or three of them. The three outputs are L/C/R the two inputs are L/R.

[Tom Mobley]

Ah, that's a different box from what I've seen. The one I have stuff for is speaker level in, line level out. I'll see if I can post a drawing.

[3dzapper]

I never tried that one Tom. Is that the one that Dr Bill was making?

[michael hurd]

The one that Rick posted is for line level, and not speaker level.The 3 rca connectors facing away from the viewer are the outputs for left, center and right. The other 2 rca connectors are the left and right line level inputs.

[Tom Mobley]

yeppers. the very same. You can swipe a line level input from a pair of speaker wires. Whenever I get the foot surgery deal behind me I'm going to start offering those boxes. I could use the same enclosure for both types. I went and looked in my DfH, found that one you're using there. They're really not that much different.

[3dzapper]

Foot surgery? What, did you have it removed from your mouth? I have to go in for that operation soon. See, I just put it in again.

Seriously, here's hope for a speedy recovery!

Rick

[Tom Mobley]

But it fits so nice in there;)

[Erik Mandaville]

Tom:

I've always liked linear taper pots on passive volume controls (like passive preamps), and that's essentially what a minibox is, as you know. Linear tapers are usually used as sort of variable resistive voltage dividers, which once set, is what's needed with the center channel. Linear tapers will be 'hotter' on lower rotations; log or audio tapers raise or lower the volume in a way that seems to match the rotation of the control.

The few boxes I built were of the speaker level input type. In either case, I think the Teac is a GREAT way to use the minibox.

Have fun with it,

Erik

[Erik Mandaville]

Oh: I forgot the value you asked about. Lower values might be better in my opinion -- 10K, 25k, 50K. -- than something like 500K. 100K should work well, too. What is the input impedance of the amplifier it's being used with? Is this the Eico? Most of those vintage amps had quite high input impedances, such as .5meg or so.

Let us know what you think!

Erik

[Tom Mobley]

Erik (with a K)

I have no pre-amp, but do have that Sony 330ES and will have a TEAC in a day or so. Just wanted to build a passive volume control so I could run it without a pre-amp. Then go to thinking about the Belle I built and the fact that the TEAC is a 3-channel amp out of the box. Now I need a volume control and a minibox. I'm going to try to put it all in one little enclosure, not a big deal but really the first time I've tried to scratch-build anything. Always before I was following along some known design or fixing something broken. Fortunately it's simple, hopefully I can get it wired up without crossing the grounds somewhere or something.