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Do you loose something when you don't run your passive bass at full volume?


SteveC

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I have 2 basses these days that I use regularly. One is an active Yamaha BB605 with Bartolini preamp and pups. The other is a passive Yamaha BB414. The 414 is noticably louder than the 605. I tried to increase the output from the 605, but it overloaded the preamp on my 550.

 

I like to leave the amp alone and I switch basses during a set. My solution is to turn the volume down a little on the passive bass. Works fine.

 

The thing is, the passive bass doesn't seem to sound the same when I don't have the volume all the way up. Am I just hearing (or not) things or is there a noticable difference in tone on a passive bass when the volume isn't cranked up?

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the output impedance changes, which affects both the bass' interaction with the cable and with the amplifier. you lose some frequency response. you also change how the pickups interact with the volume/tone circuit in the instrument itself. this is the reason why passive volume can be a very good thing and a very bad thing. it is also the reason why most people have a perma-dimed passive volume control.

 

robb.

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Here's a generic schematic for a passive pickup.

http://www.geocities.com/ricbassguy/tone_diag.jpg

The signal is generated by the pickup. The output is represented by the two little circles. One little circle (the bottom one) is grounded.

 

The volume knob is connected to a potentiometer (pot), or variable resistor. (You can ignore the tone section for this discussion.) The circuit is acting as a voltage divider. All that means is that part of your pickup signal is going out the jack on your bass, and the other part is sent through the pot.

 

Like the pickup, one side of the volume circuit output is grounded. At the lowest volume setting, the other output is also grounded. This gives zero signal through the jack (no sound). The entire pickup signal goes through the pot.

 

At the highest volume setting, the pot is essentially bypassed, and the entire pickup signal goes to the jack. (Actually, the pot remains in parallel with the jack; some basses may have a switch to totally remove the volume pot from the circuit.)

 

At in between settings, some of the pickup signal is sent through the jack and some is sent (lost) to the pot.

 

I'll defer to the real audio electronics guys to explain how the volume circuit may affect the sound. [edit: I see robb. already beat me to the punch.]

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Originally posted by robb.:

it is also the reason why most people have a perma-dimed passive volume control.

Yes, I have a perma-dimed passive volume. :thu:

 

It seems a little odd to me, however, that a passive bass is kicking out more signal than an active bass. My experience is always the other way 'round.

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Yes, it does, but not in a way I want/like.

 

I like to have one cable that I run from my bass to my TU-2 so I can mute/tune/change basses without signal to my amp or PA or anything.

 

From my TU-2 I run to my (if I use effects I insert them here) Radial JDI. I take the outs from there to my amp and PA. This way I am sending a "pre eq" signal and any efects to the PA. I can then use my amp to adjust tone without effecting the PA send.

 

The Bassbone seems like overkill when I would just be using it for volume control. Seems like there should be a better/easier way.

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A clean boost pedal on your active bass can bring up the overall output to equal your other bass. I've used one in the past with my passive Warwick, which has an incredibly low output.
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I do have the Bartolini J's so that's the answer to that question. Maybe a clean boost would work. Any suggestions?

 

I may not have to worry about it as I don't get to play my passive 4 as much as I'd like to because of the band situation. Keys can change randomly on any given night so I find I like to have the options that the 5 string gives me.

 

The 4 was a gift from my wife so I don't want to sell it or anything, and it is a great bass. I just don't get to use it as much as I'd like.

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Topic: Do you loose something when you don't run your passive bass at full volume?
No. My passive bass gains something when I don't run it at full volume. It gains a whole library of tones. My G&L SB-2 does not have a tone knob, simply two volume controls. Each one capable of several sounds between 0 and 10. The bridge pickup, though weak on it's own, adds flavor (I happen to believe Leo designed it that way).

 

This bass convinced me that perma-dimed is not always the best solution.

 

On the other hand, my Toby has been perma-dimed for so long that it is scratchy at 9.5.

- Matt W.
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Interesting. This means that if I turn the volume down on the bass, & compensate at the amp, I'll have a different range of tones available. Maybe not tones I'll use everyday, but different can be useful. Time to experiment! :idea:

 

As to the original question: why don't you just adjust the gain at the amp to make up for the difference? I'm confused. (And if you say "I don't want to walk back there & turn the knob" I'll come all the way from Melbourne to Grand forks just to bitch slap you.) :D

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What I don't understand is that you say if you increase the output from the active bass, it overloads the preamp.

 

At the same time you say that the passive bass is louder than the active bass and I'm assuming that it doesn't overload the preamp.

 

How can this be? :confused:

 

Are you plugging both basses into the passive jack?

 

Does the active bass have a trim pot which you turned up? Did you try turning it up and then turning down the bass a little?

 

One of the advantages of an active bass is that turning down the volume doesn't change the tone like it does on a passive bass.

 

I'm having some of the same problem when switching from my fretless to my fretted. Not only are the output levels different, but they require completely different eq settings.

 

However, while plugging and unplugging it only takes a few seconds more to turn the dials...after all I do have to turn the volume off when I unplug so it's not a big deal to turn it back on at a different level.

 

I'm not alternating songs...I'm using the fretless for one hour and then switching to fretted for the rest of the night.

 

But I'm sure you'll find a pedal. There is a pedal for everything these days. :D

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Did somebody say pedal?

 

http://www.seymourduncan.com/images/effects_pedals_desc.jpg

 

I have a Seymour Duncan Pickup booster pedal.

 

From their website:

 

By rotating the gain control knob you can add pure, flat-EQ gain, ranging from 6dB to 25dB
I use it on one of my passive basses that has a very low output level. Tonally I love the bass, and don't want to change the sound other than to increase the level presented to my amp.

 

You could use it by adjusting the amp for your bass that has the hotter signal, and then adjust the gain on the pedal so the bass with the lower signal matches the hotter bass.

 

Then, as you switch instruments on the gig, just use the footswitch to turn it on/off.

 

:thu:

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Originally posted by jeremy c:

What I don't understand is that you say if you increase the output from the active bass, it overloads the preamp.

 

At the same time you say that the passive bass is louder than the active bass and I'm assuming that it doesn't overload the preamp.

 

How can this be? :confused:

 

Are you plugging both basses into the passive jack?

 

Does the active bass have a trim pot which you turned up? Did you try turning it up and then turning down the bass a little?

 

One of the advantages of an active bass is that turning down the volume doesn't change the tone like it does on a passive bass.

I run the eq on the bass flat. When I turned up the trim pot, all I got was a distorted sound. There is only one input on my head. I assumed I was overloading the input on the amp. I thought it was strange as well. The passive bass doesn't overload the preamp. I am confused as well.
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Originally posted by dcr:

Interesting. This means that if I turn the volume down on the bass, & compensate at the amp, I'll have a different range of tones available. Maybe not tones I'll use everyday, but different can be useful. Time to experiment! :idea:

 

As to the original question: why don't you just adjust the gain at the amp to make up for the difference? I'm confused. (And if you say "I don't want to walk back there & turn the knob" I'll come all the way from Melbourne to Grand forks just to bitch slap you.) :D

It's not a question of my stage volume. The problem is the PA. We don't have someone to run it during the set so if I switch basses, the passive will be much louder, thus messing up the mix.
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This effect is well known & pretty obvious in the guitar world - loosing tone/going muddy when turning down the volume.

 

There's a useful mod for guitars that involves soldering a small value cap plus a resistor (I can't remember the values, but I'm sure someone else will know) across the vol pot input & output.

 

This bleeds the treble straight to output & stops the mud.

 

I have it on several of my guitars, but haven't tried it on my one passive bass, so I don't know if it'll have the same effect on the low frequencies, but I suspect it might.

 

Torrez Amps, I know, sell these as little mod kits.

 

Geoff

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Originally posted by Geoff Byrne:

This effect is well known & pretty obvious in the guitar world - loosing tone/going muddy when turning down the volume.

 

There's a useful mod for guitars that involves soldering a small value cap plus a resistor (I can't remember the values, but I'm sure someone else will know) across the vol pot input & output.

 

This bleeds the treble straight to output & stops the mud.

 

I have it on several of my guitars, but haven't tried it on my one passive bass, so I don't know if it'll have the same effect on the low frequencies, but I suspect it might.

 

Torrez Amps, I know, sell these as little mod kits.

 

Geoff

Here's a link to a page on guitarnuts.com that explains that technique:

 

http://www.guitarnuts.com/wiring/volpass.php

 

;)

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The advice on battery condition is a good place to start.

 

If the battery is ok you could lower the pickup on the passive bass to lower it's output.

 

Or you could get the bass bone which will ,

1) replace the JDI as a direct box.

2) give you full control of tone and volume for both basses.

3) add a mute switch for tuning.

4) add a buffered output for your tuner for both basses.

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The battery is good.I did lower the pups on the passive as well. Didn't do that much.

 

I suppose a BassBone might be an option. The only pedals I use now are tuner and DI. I could still send a "flat" signal to the PA and use my amp for any necessary stage corrections. The Bassbone doesn't have the Jensen transformer in it though, does it? Maybe that's not a big deal.

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Originally posted by SteveC:

Originally posted by jeremy c:

What I don't understand is that you say if you increase the output from the active bass, it overloads the preamp.

 

At the same time you say that the passive bass is louder than the active bass and I'm assuming that it doesn't overload the preamp.

 

How can this be? :confused:

 

Are you plugging both basses into the passive jack?

 

Does the active bass have a trim pot which you turned up? Did you try turning it up and then turning down the bass a little?

 

One of the advantages of an active bass is that turning down the volume doesn't change the tone like it does on a passive bass.

I run the eq on the bass flat. When I turned up the trim pot, all I got was a distorted sound. There is only one input on my head. I assumed I was overloading the input on the amp. I thought it was strange as well. The passive bass doesn't overload the preamp. I am confused as well.
Is there a passive/switch for the one input?

 

 

www.ethertonswitch.com

 

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There is a pad, but again, the problem isn't with the amp, it's at the PA. I send both basses to the PA before anything to do with my stage amp. The stage amp is just a monitor in most cases.

 

The volume issue needs to be dealt with before the signal goes to the PA.

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