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Why Volume/Volume?

#21
thepontif said:
The issue is that with 4 250k elements in parallel with each other, the impedance of the circuit is 62.5k ohms where with 3 250k elements the impedance is is about 83.3k ohms. Just like with 4 8 ohm speakers in parallel vs. 3 8 ohm speakers. The amp will behave differently into 3 speakers than 4. Having a balancer and a master volume is electrically the same as having a volume for each PU, a master volume, and a tone control (which might be a solution for some of you, actually). The master volume "loads" the balancer and can make it behave strangely. Another issue is that most balancers are LINEAR taper from center to full which is only a half a turn anyway, where a volume control has an audio taper and a full rotation. Of COURSE vol/vol is more sensitive. I've found that in a Fodera with Barts, the balancer is really frustrating. With SD's or Aeros it's fine. In my bass, with SD's, the path when active is balancer-preamp-volume-output driver. The preamp buffers the balancer from the volume control. In my bass I don't have any difficulties with "fine tuning" the blend control.

The new Fodera preamp now actually exists. There are two in service and one more on my bench. One of the big improvements we made was a double bypass situation. The bypass switch switches 2 separate active stages in and out at the same time. So the signal goes...
PU's-balancer-tone-gain/buffer/EQ-volume-output driver

This way, the volume control's position has no effect on the sound, it doesn't load the balancer, and the ouput impedance is a nice, steady 600ohms regardless of volume, which is WAY lower than most, if not all internal preamps. It'll swamp out cable capacitance even in a cheap cable. The better news is that noise is reduced because we actually have a driven active ground and ground planes which help to hold ground good and steady in the even that noise picked up by the cable tries to move ground around, and even better is that the whole circuit only draws MICROamps of current. Considerably less than 1mA. This means about 650 hours WORST CASE battery life.
There's a lot more that's improved in it, but this "balancer issue" is one we addressed. My $0.02.
Click to expand...


Very cool Mike, and it's nice to know that what some of us hear as much smoother operation with a volume/volume circuit is based on fact! I'll look forward to trying the new Fodera pre sometime... seems like you've done some innovative things which brings a balancer much closer to the performance some of us have been looking for.
 
#22
thepontif said:
The issue is that with 4 250k elements in parallel with each other, the impedance of the circuit is 62.5k ohms where with 3 250k elements the impedance is is about 83.3k ohms. Just like with 4 8 ohm speakers in parallel vs. 3 8 ohm speakers. The amp will behave differently into 3 speakers than 4. Having a balancer and a master volume is electrically the same as having a volume for each PU, a master volume, and a tone control (which might be a solution for some of you, actually). The master volume "loads" the balancer and can make it behave strangely. Another issue is that most balancers are LINEAR taper from center to full which is only a half a turn anyway, where a volume control has an audio taper and a full rotation. Of COURSE vol/vol is more sensitive. I've found that in a Fodera with Barts, the balancer is really frustrating. With SD's or Aeros it's fine. In my bass, with SD's, the path when active is balancer-preamp-volume-output driver. The preamp buffers the balancer from the volume control. In my bass I don't have any difficulties with "fine tuning" the blend control.
Click to expand...
Wow, thanks for the explanation, your excellency! I always thought that the extra potentiometer may be the culprit as to why VOL/VOL alwasys seemed more to my liking for passive basses. Makes perfect sense.

This is for passive wiring only. In an active setup where each pickup can be individually buffered before the blend control, all bets are off.
 
#23
Philbiker said:
Wow, thanks for the explanation, your excellency! I always thought that the extra potentiometer may be the culprit as to why VOL/VOL alwasys seemed more to my liking for passive basses. Makes perfect sense.

This is for passive wiring only. In an active setup where each pickup can be individually buffered before the blend control, all bets are off.
Click to expand...

I assume that most active basses do not have this individual buffering before the blend control that you mention, leading to similar issues as in the passive circuit?
 
#26
This becomes tricky and a matter of taste more than anything else. For me, I like the "tip of the hat" to the old Fender thing where you have alnico PU's connected straight to a volume or balance control. In this case, the PU's load one another through the controls in a non-linear way that gives you that sort of "vintage"-ish vibe. It's a sort of crosstalk between the PU's that is very desirable to some people, myself included. If the bridge PU (for example) is full on and the neck is off...then you turn the neck volume up slowly, you're not just increasing the volume of the neck PU relative to the bridge, you're also changing the frequency characteristics of the bridge PU and, really, the whole circuit up to the preamp. If you could physically get the neck PU so it was not picking up the string and listen only to the bridge PU while you turned the neck volume, you'd hear some kind of change in the sound of the bridge PU.
The other BIG difference between vol/vol and blend/vol is...say the bridge is at 80% and you roll in the neck to 80%. The PU's are the same level as one another, but there's a bunch of resistive isolation between them which changes the way they interact. I can't say how, exactly...it's not something I've spent time investigating, but it's important to some people, and it's not possible to do in a bal/vol setup.
So in the Fodera preamp, there's no buffering before the balancer. If there were, I'd be using 25k or maybe even 10k pots to reduce noise since the buffer can drive that load easily. The PU's are passively connected to one another and then they hit the tone control...then the preamp input. The input impedance of the preamp is extremely high...over 1 Megohm...so it doesn't load any of the controls or the PU's. So when the bass is in active mode, the front end is still passive. The difference is that instead of having a wimpy passive output have to drive a cable to get to the preamp, it only has to drive an inch of PCB trace to get to the preamp input. Then the output of the preamp is put across the master volume. Then you need an output driver, or else you defeat part of the purpose of the preamp when you lower the volume slightly. Without an output driver, at half volume you'll have an output impedance of in the 100's of kilohms. Not good for noise etc. You could use a lower value (say 10k) vol pot which would at least get you closer, but then when you went passive you'd have major problems with that low value severely loading the balancer and tone control. If you buffer the PU's individually first, you have a much more linear situation. The outputs of the buffers SHOULD be linear and not affected by one another at one frequency more than another. From an engineering standpoint it's CLEANER to receive the PU's as differential signals and buffer them before blending. But my whole philosophy is to strike as nearly perfect a balance between "correct" process and real-world desireable result as is possible. It's not for everyone, but my opinions and practices come from actually doing the playing in the hot seat as much as from having artists tell me what they like. That's a big divide, let me tell you. No amount of endorsers' input makes up for knowing first hand what needs to be done. For me, it works the best, but I've also done it enough to be able get different results for different people who don't like what I like. In a Fodera bass, though, it's my (and Fodera's) vision of a bass preamp and we continue to refine and improve it.
 
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#27
RyreInc,
Just to clarify, the balancer's operation isn't necessarily affected by the active electronics. The issue is mainly the way the 2 PU's and the balancer react with one another. The preamp can be implimented in a way that avoids screwing up the operation of the balancer. But passive or active, the balancer should behave the same, as it does in your bass...and mine.
 
#28
PhilBiker,
Most active basses do not have individual buffering before the balancer. Some do, but most don't. If you have active PU's like EMG's, they're buffered by default. And again, it's not better or worse. It's just another way to get the skin off the cat. There's a lot of diversity in the bass world now. No reason to condemn anything unless it just doesn't get results for ANYONE.
 
#30
As much as I like the volume, volume, tone, concept,
I find it unusable in many concert or important performance
situations. I can't take the time or focus away from
the music to "twiddle" nobs. If I'm in the middle of a
song, my focus needs to be there, so if I need more
volume one knob is just SO much easier. Everything
else has to wait till a spot in the song where I have
time, but I still can't make noise evening out the volumes.
Single volume, pan setups may not be perfect, but
they are much easier in actual playing situations.
 
#32
I'm not a luthier nor electrician, but for those preferring the vol/vol/tone, would it be possible to install a simple on off toggle that would mute the output? Or maybe a pull knob for the tone or one of the volumes that does the same thing..?
danny
 
#33
What is the deal with one master volume and a pickup selector switch, like the Fender RB5 and some butique stuff?
I'm thinking of getting a bass made, and the switch seems like it would be perfect for quick switching during a song, maybe for things like soloing the neck pickup for the verse and the bridge pickup for the chorus etc.
Any opinions/experiences?
 
#34
malicous said:
What is the deal with one master volume and a pickup selector switch, like the Fender RB5 and some butique stuff?
I'm thinking of getting a bass made, and the switch seems like it would be perfect for quick switching during a song, maybe for things like soloing the neck pickup for the verse and the bridge pickup for the chorus etc.
Any opinions/experiences?
Click to expand...
If you want to have choices of ONE/BOTH FULL/TWO a switch is better than either pan or vol/vol/tone. However, that doesn't allow you to blend the pickups.
 
#35
I'm amazed that this thread got to the bottom of page 2 without anyone mentioning the Audere Audio preamp since you can have it configured with master volume plus individual vol/vol for the pickups. :hyper:

I have also always preferred vol/vol on passive basses. Glad to see I wasn't hearing things......
 
#36
Yeah that's a good idea. I've considered that for my own bass, but not for Fodera. Maybe as an option... Truth is, compared to most, the Fodera preamp is REALLY expensive to make. Options magnify that cost grossly. I could do it on one of my custom preamps. Like 2 stacked controls. One is Neck/Bridge vol and one is Master Vol/Passive tone. The master volume could go after an active stage so you'd have exactly a vol/vol/tone setup both functionally and electrically with the added advantage of a master volume control that wouldn't effect frequency response. And an output driver for low output impedance. Anyone interested in doing this should let me know via my website. Maybe we could work an R&D deal of some kind.
 
#37
B String said:
As much as I like the volume, volume, tone, concept,
I find it unusable in many concert or important performance
situations. I can't take the time or focus away from
the music to "twiddle" nobs. If I'm in the middle of a
song, my focus needs to be there, so if I need more
volume one knob is just SO much easier. Everything
else has to wait till a spot in the song where I have
time, but I still can't make noise evening out the volumes.
Single volume, pan setups may not be perfect, but
they are much easier in actual playing situations.
Click to expand...


Interesting how we all use this stuff differently. I never us the volume control to set my volume.... it's always up full on my volume/blend basses and both up full (except when blending) on my volume/volume basses. I find many basses sound best with the volume all the way up. I vary the volume using my touch, and maybe have to adjust my amp once a night if the band starts getting loud.

Interestingly, since my main 'tweeking' throughout the night involves primarily blending toward the bridge pickup for a punchier tone, and both full open for a deeper tone or when slapping, I actually find the volume/volume much easier to use in a live setting, due to the much easier adjustment due to the long taper mentioned by Mike a few posts back (i.e., there is a very small 'sweet spot' in most blend controls... if you don't hit it just right, you very quickly go from 'blend' to totally on/off... whereas in the volume/volume, there is quite a bit of forgiveness... you have a lot of play in the taper)

Anyway, this is a fun discussion and I can surely see how both circuits have their advantages.
 
#39
bassmonkeee said:
I'm amazed that this thread got to the bottom of page 2 without anyone mentioning the Audere Audio preamp since you can have it configured with master volume plus individual vol/vol for the pickups. :hyper:

I have also always preferred vol/vol on passive basses. Glad to see I wasn't hearing things......
Click to expand...

Per Mike's comment above, that can result in the same issues as the volume/blend. See his first detailed post toward the beginning of this thread.
 
#40
Im gonna be a real pain in the ass and say I prefer my 4-way switch to either vol/vol or vol/blend. I have 4 positions, neck solo, both in series, both in parallel, and bridge solo. Combined with the right pre-amp, I am able to shape my tone to just about anything I want, and no volume issues (other than series is louder than the others by a bit).
 

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