Bottlehead Forum

Bottlehead Kits => Crack => Topic started by: jrihs on February 07, 2011, 05:23:30 PM

Title: Volume pots
Post by: jrihs on February 07, 2011, 05:23:30 PM: Found this on e-bay - Valab 23 Step Attenuator Potentiometer 100K Stereo Log - anyone try it yet? 25$, I might go for it.

http://cgi.ebay.com/Valab-23-Step-Attenuator-Potentiometer-100K-Stereo-Log-/290522587402?pt=LH_DefaultDomain_0&hash=item43a47ee10a

Also...I notice alot of reccomendations for PEC. The audio note pot is about the same price. Can anyone offer any comparisons?

Thanks Mucho!!!
Title: Re: Volume pots
Post by: InfernoSTi on February 08, 2011, 12:51:21 AM: Quote from: jrihs on February 07, 2011, 05:23:30 PM
Found this on e-bay - Valab 23 Step Attenuator Potentiometer 100K Stereo Log - anyone try it yet? 25$, I might go for it.

http://cgi.ebay.com/Valab-23-Step-Attenuator-Potentiometer-100K-Stereo-Log-/290522587402?pt=LH_DefaultDomain_0&hash=item43a47ee10a

Also...I notice alot of reccomendations for PEC. The audio note pot is about the same price. Can anyone offer any comparisons?

Thanks Mucho!!!

I have used that eBay vendor for a set of 640H grid chokes and they arrived well packed and on time. I also have used the PEC audio pot which was about $35 and like it very much. Sorry, no comparo but perhaps a bit of comfort that the seller is reliable...

John
Title: Re: Volume pots
Post by: Grainger49 on February 08, 2011, 02:17:42 AM: I bought several things from Valab. I bought the 47uF PP caps that replaced my Paramour power supply caps there.

His ads might be a little exaggerated, well, maybe a lot. But I have only gotten good service from him.
Title: Re: Volume pots
Post by: jrihs on February 10, 2011, 12:08:57 PM: Thanks,

After doing some more research, I probably should have called this attenuators vs. vol. pots to generate more interest.

Is it worth it to build your own passive attenuator kit?

Percy audio has some interesting options...
Title: Re: Volume pots
Post by: HF9 on February 17, 2011, 06:49:23 PM: Quote from: jrihs on February 10, 2011, 12:08:57 PM
Is it worth it to build your own passive attenuator kit?
Sure, you get to pick the resistors of your choice and configure the value to your taste (log versus linear). If you're an experienced solderer, it'll take you a couple of hours to build. Check out Goldpoint and Elma for attenuators that you can stuff with resistors.
Title: Re: Volume pots
Post by: Grainger49 on February 17, 2011, 11:30:12 PM: Jrihs,

The poster VoltSecond has a page on stepped attenuators and volume control schemes.

Look here:

http://www.siteswithstyle.com/VoltSecond/12_posistion_shunt/12_Position_Pure_Shunt.html

One crafty poster on the old board suggested that you build an S5 attenuator (on VoltSecond's page) with generic metal film resistors. You start with the series resistor being a good "designer" resistor but then find what steps you use the most and then replace only those steps with $5 resistors. That saves cash.
Title: Attenuator calculator
Post by: electrovice on February 18, 2011, 01:37:44 PM: Here is a link to a program to calculate the resistors required for an attenuator. Hopefully it is of some use to somebody.

http://margo.student.utwente.nl/klaas/audio_step.htm

John
Title: Re: Volume pots
Post by: jrihs on March 04, 2011, 05:24:01 AM: Outstanding! Thanks for the advice. I have alot to learn about attenuators. If one was to take the easier rout of prefab though...would the Khozmo attenuator from parts connextion be an advisable route to take? assuming it fits? any experiance with this? I'm prety sure the Valab attenuator kit would not fit in the Crack...no pun intended.
Title: Re: Volume pots
Post by: HF9 on March 04, 2011, 10:09:22 AM: It's hard to say, the Khozmos are rather large (W42 x H46 x L48 mm). A DACT will fit without issue.
Title: Re: Volume pots
Post by: Jim R. on March 05, 2011, 11:23:27 AM: Yes, I'd think the kozmo would not be an easy fit -- certainly not a drop-in, and even with surgery may not clear the C4S boards on the driver tube if you want to go with the speedball upgrade.

-- Jim
Title: Re: Volume pots
Post by: deltaunit on March 28, 2011, 03:24:20 AM: Does anyone know if the valab will fit a crack with speedball? Are these stepped attenuators a good upgrade?
Title: Re: Volume pots
Post by: jrihs on March 29, 2011, 08:39:26 PM: I looked into getting a valab with dale resistors on ebay and asked the creator how big it was...I forget what he said but I figure it was half an inch too big (3.5"?). I think it would have been a very cost effective solution at $50 bucks for a completed stepped attenuator.
Title: Re: Volume pots
Post by: deltaunit on March 30, 2011, 04:26:15 AM: Hmm that doesn't sound good :(

I think it will be a couple of weeks before my speedball kit makes it over to the UK so please forgive another question but does anyone know if an Alps Blue (2.7cm w x 2.4cm h x 2.5cm d) would be an easy fit?

Thanks
Title: Re: Volume pots
Post by: Beefy on March 30, 2011, 04:56:44 AM: Quote from: deltaunit on March 30, 2011, 04:26:15 AM
I think it will be a couple of weeks before my speedball kit makes it over to the UK so please forgive another question but does anyone know if an Alps Blue (2.7cm w x 2.4cm h x 2.5cm d) would be an easy fit?

The TKD 2CP2511 (http://www.partsconnexion.com/tkd_64187.html) fits, and it is slightly larger than the Alps Blue. You just need to make the mounting hole larger.

FWIW, the TKD is a much better pot than the Alps Blue. If you are going to upgrade the stock pot, I can highly recommend the TKD.
Title: Re: Volume pots
Post by: STURMJ on March 30, 2011, 04:11:47 PM: I used the Alps blue in my crack (hun?) perfect fit, even with the speedball boards. Actually the speedball board on that side of the amp is flush and right next to the pot, not touching.
ps. here is a pic
Title: Re: Volume pots
Post by: deltaunit on March 31, 2011, 06:41:44 AM: Thanks for the replies, I think I might be able to swing an Alps Blue through work so may go for that. Excellent looking build STURMJ. Cheers
Title: Re: Volume pots
Post by: jrihs on April 04, 2011, 06:33:52 PM: ARRRGHH......Can't make up my mind between the TKD-70897 and DACT at twice the price! I'm sure there is a difference. Just not sure I would hear it. ONE thing could help me decide....which one does not require modifying the hole-in-the-plate? if either or neither. Any strong opinions on either Pots?

Thanks!!
Title: Re: Volume pots
Post by: Doc B. on April 04, 2011, 06:50:10 PM: FWIW I prefer Goldpoints over the DACTs.
Title: Re: Volume pots
Post by: jrihs on April 04, 2011, 07:02:31 PM: OK! I was just reading about those and others seem to prefer it as well. Are you referring to the standard or custom goldpoint? Does it require a bigger hole? What sonic qualities do you like about it? More transparent?
And THANKS!!
Title: Re: Volume pots
Post by: Beefy on April 05, 2011, 02:49:26 AM: Quote from: jrihs on April 04, 2011, 06:33:52 PM
ARRRGHH......Can't make up my mind between the TKD-70897 and DACT at twice the price! I'm sure there is a difference. Just not sure I would hear it. ONE thing could help me decide....which one does not require modifying the hole-in-the-plate? if either or neither. Any strong opinions on either Pots?

Simple question...... how confident are you that you can find your perfect listening level on a 24 step attenuator? Especially given that the DACT is 4dB or greater steps up to -34dB - I don't even get close to that high a volume with my Crack/Speedball/5998.
Title: Re: Volume pots
Post by: pro_crip on April 05, 2011, 03:56:53 AM: I made the custom goldpoint using their list and dale rn60 resistors. If your soldering skills are up for it, you can use surface mount. From what I recall, it was a straightforward build. You start at r1 and work your way all the way over to r24. The build takes some time, but that just gives you more fumes to huff ;P Thanks for listening.

Rich
Title: Re: Volume pots
Post by: jrihs on April 05, 2011, 04:03:54 AM: So I take it the custom goldpoint would fit then?
Title: Re: Volume pots
Post by: jrihs on April 05, 2011, 07:15:21 AM: Well, I guess all my questions are moot since I just ordered the goldpoint standard!
Cheers!!!