Bass blend knob

[WDeeGee]

Hi. I got me a nice used Japanese bass, it sounds fantastic, passive pickups are great. This is however my first bass with a blend knob - but there's something unusual about it.
When in the middle position (it has a stop there) I hear both pups but the volume is less. Turn it either way and the other pup fades out but the volume increases. Is this normal?

I would just prefer to have no volume drop. My other bass has 2 volumes, one for each pickup, and I can dial in or out one ofthe pups and not hear any drop in volume.

Some advice would be welcome. Thanks!

 

[alex1fly]

Sounds kind of like a Jazz Bass type setup with two volumes - there's a bit of volume loss when they're both maxed. But on a Jazz the mids clean up a bit so you get a nice cut through the mix.

I had a bass that didn't drop volume with the blend in the middle. It was a Schecter Stilletto Session with active EMGs. But my two pickup bass now has active EMGs and the two volume knobs do the volume dip when they're both maxed (or equal).

It's something you just have to deal with, I think. Not a deal breaker if you can figure out how to be musical with it. Others might have ideas. Maybe there's a re-wiring component, wouldn't be worth it for me though. I tend to get my tone and just roll.

 

[Mincer]

I've also seen this where 2 pickups were wired out of phase, so the biggest loss was when both were up full. I doubt that is what is going on here, but I've seen this with replacement pickups that were accidently wired that way.

 

[ICTGoober]

Out of phase - that's the culprit.

 

[beaubrummels]

Depends on how much volume loss there is. If it's significant, it might be just pickups out of phase. If it's subtle, like a darkening also, it could be additional loading from either the master volume or tone. Certain blend knobs are just like two volumes stacked, and if there is a master volume, they will interact. Replacing the blend with a type that is truly center-off, or replacing the master volume with a higher value pot would help it a bit.

 

[dystrust]

I had a bass that didn't drop volume with the blend in the middle. It was a Schecter Stilletto Session with active EMGs.

The EMG Active Balance control has no volume loss when panned to the center, unlike a typical blend pot where you'll have a little bit of loss due to loading.

 

[alex1fly]

Here's a Talkbass thread where they go in depth about it. Can't vouch for any of the info, but it's pretty much this discussion with more posts.

https://www.talkbass.com/threads/vo...ckups-all-the-way-up-on-jazz-bass-why.975657/

 

[Artie]

Out of phase - that's the culprit.

Not necessarily. When a blend pot is in the middle, the pups see half the resistance. Ie., double the load, and only part of the volume. It's normal. It's why I bought the EMG ABC blend pot for my Toby.

Now I just gotta get off my lazy butt and install it.

 

[Mincer]

It really depends on how quiet it gets when both are on full. Usually if it is indeed out of phase, the tone suffers too, not just the volume.

 

[JB_From_Hell]

My passive Warwick doesn’t lose any signal with the blend centered. It has stacked DiMarzio humbuckers now, but it was the same with the stock singles.

 

[Mincer]

With some basses, it isn't an issue. I have heard it on some older Jazz basses, though. The pickups weren't out of phase, either.

 

[Aceman]

I've also seen this where 2 pickups were wired out of phase, so the biggest loss was when both were up full. I doubt that is what is going on here, but I've seen this with replacement pickups that were accidently wired that way.

That was my guess

 

[alex1fly]

Big volume loss? Out of phase. Noticeable but not big volume loss? Something else. If it's the second, this is pretty common. The volume loss is more of a frequency cancellation and gives two pickup basses their signature sound. Dips out some of the mids and helps it cut through the mix. Players get around this by slightly favoring one pickup or the other with their blend or volume knob. It is kind of neat though because it's like having a passive EQ mid control right there on your bass.

What happens when you nudge the blend knob slightly towards one pickup or the other?

 

[WDeeGee]

Hi, OP here, did some research and found the answer online.


A blend pot is two pots on top of each other with reversed tapers: if one pot is at 100%, the other is at zero. If one pot is at 30% the other is at 70%; in the middle position, both tapers are at 50%, hence the volume drop at the center position.
A local online store sells different types of blend pots: one of them is advertised as having no volume drop in the center position. Meaning, both tapers are at 100% in the middle position. Turn left or right and one of them tapers off towards zero while the other remains at 100%. So basically the taper is at 100% until halfway, and only then begins to taper off.

My initial though was out of phase wiring, but this wasn't the case.

 

[Mincer]

That would be great if there is no drop in the middle. Let us know how it works out after you install it.

 

[beaubrummels]

Could have found the same answer in post #5, but as long as he found it, ok.

 

[alex1fly]

Could have found the same answer in post #5, but as long as he found it, ok.

I'd like some food with that salt, please

Just teasing.

So what's the plan? Is it important enough to rewire? Or are you going to work around it? Still lots of knob positions with full volume. Also, in a band setting I find a volume boost on the bass to be pretty useful... you could play in the center position most of the time and then treat the blend knob like a boost. Just thinking out loud.

 

[Artie]

A blend pot is two pots on top of each other with reversed tapers: if one pot is at 100%, the other is at zero. If one pot is at 30% the other is at 70%; in the middle position, both tapers are at 50%, hence the volume drop at the center position.

Actually, that's a "ganged" pot, which most people wouldn't use for a "blend" pot. A true blend pot only has a resistance track halfway around. So, in the middle, both wafers are at 100%.

https://www.bourns.com/docs/ProAudio...sn=f3258ef1_13