Where can I get pots that ...

[BFunk]

I was talking to my luthier the other day about the lack of apparent sweep in pots. In his experience, most pots don't have a significant change in resistance until the last ten percent. Many seem to be more of an on/off switch than a true sweep. He told me he just tested a new batch of cts 500K pots and found them all the same. he said there are some very expensive pots, I think the name was Bourne, that have a really good sweep. The downside is that they cost about $30 ea. Does anyone know where to get these pots or have other recommendations?

[line6man]

You don't need any fancy pots, just pots of the other taper. If you are using audio taper pots, try linear tapers.

[i_got_a_mohawk]

What application are you using them for? Volume? Tone? Active EQ?

Pots come with a variety of tapers, audio (log), linear and reverse (anti) log are the most common types.

For instance:




You shouldn't be having to pay $30 a pot to get a pot with a taper that works for you.

(I'm assuming by true sweep you are looking for a linear increase in resistance, for most audio applications I find audio (log) pots to have a more uniform shift in volume).

[SGD Lutherie]

Originally Posted by BFunk

In his experience, most pots don't have a significant change in resistance until the last ten percent.

That's an audio, or log taper. Try linear taper.

Bourns "guitar pots" are $4. Their "fancy" sealed pots are about $10.

[temmrich]

^^ what these guys said.
You sure this guy is a real luthier? This isn't uncommon knowledge. He should definitely be aware of the different types of tapers, at least audio and linear. those are the most commonly used in basses/guitars.

[SGD Lutherie]

A lot of otherwise skilled luthiers and repair people don't seem to know much about the electronic end of things.

I had a Jazz bass come into my shop that had active EMGs and a Sadowsky preamp. The owner had the preamp installed by a fairly well know builder who makes very nice basses. I've played one of them before.

The owner was complaining that the bass had very little output, and sounded very dull. I plugged it in, and he was right. Almost no signal.

So I unscrewed the control plate to take a look. I noticed I didn't see any red power wires coming from the EMGs. In fact, I didn't see the standard shielded EMG cables either, just a twisted pair of wires for each pickup.

So I removed the pickups, and the luthier had cut the EMG cables off of the plus, and soldered on a twisted pair of wires. The red power wire was never reconnected to the battery!

I can't imagine why someone would do this. Did he think you can't use active pickups with a preamp? Did he think removing the power made them passive? Did he think the twisted pair of wires was better than shielded cable?

I have no answers for that. But I'm guessing it was a combination of all those misconceptions.

[Scott in Dallas]

I used to work with a luthier like that. My advice is to stop returning his calls.

[BFunk]

Thanks for the generous feedback. This is a luthier with a very good reputation that I have been working with for years. I brought a p/j to him to have it wired v/v/t with a thee way switch to select the pickups. The bass has dimarzio model p and model j with 500k volume pots and a 250k tone pot. I noticed that when I set the switch to the middle, set one volume to max, and slowly roll up the other volume from min to max, I get almost input from the second pot until the last bit of sweep and suddenly it comes on pretty loud. When I showed this to him, he asked me to switch to one pickup and sweep the volume from min to max. Sure enough, there was very little output until the last 10% of the sweep. At that point the volume jumped significantly with only a slight rise as I swept to the end of travel. The results were the same for the other pickup. He said that it is the unfortunate truth about your average volume pot. He said to get functionality like you are asking requires a very expensive pot that is normally only found in very expensive custom instruments.

I just looked on allparts for the item he is referring to. I found these for $28 ea.: http://www.allparts.com/EP-5686-000-...ot_p_1500.html. I really don't think the guy is out of line from what I can see.

[BFunk]

Allparts has these: http://www.allparts.com/EP-5086-000-...ot_p_1488.html for $17 ea. I am not sure what the difference is.

[SGD Lutherie]

Originally Posted by BFunk

Allparts has these: http://www.allparts.com/EP-5086-000-...ot_p_1488.html for $17 ea. I am not sure what the difference is.

The other one had a longer shaft for a thick top like a Les Paul.

[SGD Lutherie]

http://www.wdmusic.com/shop_by_categ...urns_pots.html

[i_got_a_mohawk]

Originally Posted by BFunk

He said that it is the unfortunate truth about your average volume pot. He said to get functionality like you are asking requires a very expensive pot that is normally only found in very expensive custom instruments.

Log pots should work better in volume control situations. Linear increases in power don't provide linear increases in volume (why a 200 watt amplifier isn't twice as loud as a 100 watt amplifier, for instance). Log pots work better in volume applications for me, but I know that others find linear pots to provide a smother increase in volume.

Try a linear pot, it may work better for you :

http://www.allparts.com/EP-0228-000-...ot_p_1295.html

I'd also say it isn't an unfortunate truth, even cheap volume (audio/log) pots have a fair representation of a logarithmic curve, so much so it isn't going to appear to jump any more than a true logarithmic (hell, less of a jump if you go by the graph listed earlier).

[walterw]

Originally Posted by BFunk

He said that it is the unfortunate truth about your average volume pot. He said to get functionality like you are asking requires a very expensive pot that is normally only found in very expensive custom instruments.

I just looked on allparts for the item he is referring to. I found these for $28 ea.: http://www.allparts.com/EP-5686-000-...ot_p_1500.html. I really don't think the guy is out of line from what I can see.

Yeah, that's just dumb. You're describing exactly how audio taper pots work as volumes in basses.

All you need are CTS linear taper volumes, which are no more than the audios in that same catalog.

[BFunk]

I thought audio (log) taper pots have a smoother increase in volume because it compensates for the logarithmic nature of gain. It seems to me that linear pots would be less smooth, with all the gain happening toward the beginning.

[BFunk]

Great video on pots http://www.youtube.com/watch?v=RdfIZEB2rdM

[i_got_a_mohawk]

I find audio taper works better in volume applications, even on bass.

Some people don't and prefer linear.

Try both and see which you prefer (you could even try it with some dirt cheap pots initially).

[walterw]

It's all about the signal path; with guitar and its typical overdriven, compressed amp tone, audio taper volume pots work evenly to control the amp overdrive.

With bass and its typically clean sound, audio volumes act just like the OP is complaining about: little volume for most of the turn, then jumping up loud at the top.

The effect is exaggerated with higher-resistance pots like the OP has.

This is worth a search, the topic has been thoroughly discussed. Try "linear taper" for a ton of threads.

[SGD Lutherie]

Originally Posted by BFunk

I thought audio (log) taper pots have a smoother increase in volume because it compensates for the logarithmic nature of gain. It seems to me that linear pots would be less smooth, with all the gain happening toward the beginning.

But they don't work well for blending two pickups, like on a Jazz bass. Audio taper works better as a master volume.

When you use audio taper for blending, you aren't concerned with a gradual increase. You want the change spread out more. On an audio taper most of the volume is scrunched up between 8-10. That makes it very hard to pull one pickup back a little.

Audio taper is good for fades, like on a mixer. Not so good for setting the level of something.

Also, many pots use two linear tapers to approximate an audio taper. So the taper isn't as smooth as it can be.

[testing1two]

I'm sure forum rules prevent him from mentioning it, but David's prices on the Bourns premium pots are way less than AllParts. http://sgdlutherie.com/pages/parts.html

[BFunk]

Geez, I'll say!!