• There is a glitch in the forum software that we are trying to track down. For now, please make sure that the title of your new thread does NOT start with a number (digits). Otherwise, your post will appear to be saved but future attempts to read it will be met with an error message indicating the thread/post cannot be found. ~ admin

katsumura78

Well-known member
Joined
Apr 22, 2012
Messages
71
So I got my JP15 a few weeks back but had to return it, waiting on another. My question is in regards to the boost built into the guitar. I know the guitar can't be used without a battery as well so when the boost isn't engaged is the circuit effecting the tone of the pickups or is it completely bypassing the entire thing?
 

drewbixcubed

Moderator
Joined
Jul 7, 2005
Messages
355
Location
San Luis Obispo
The preamp in the guitar is always in use. But this is to the players benefit, as it maintains the pure tone of the pickups, but doesn't allow for things like cable capacitance or other "outside" influences to affect your tone (like low input impedance to pedals in your signal chain)! The tonality of of the pickups remain as intended/designed when volume is lowered (no loss of highs), or if cable length (capacitance) is increased, etc... In addition, the boost is simply a transparent gain increase of up to 22 dB. Which, when used with a "clean" tone, will increase volume as well as add a little crunch. When used with a dirty channel, will drive the amp's input and thus increase the sustain and distortion.

Other things to note: There is no "EQ" in the magnetic circuit and the tone knob on the guitar still affects the pickups in the traditional sense.
 

katsumura78

Well-known member
Joined
Apr 22, 2012
Messages
71
Thanks for the reply and explanation, I knew something was going on tone wise but couldn't put my finger on it. This makes a lot more since. The 15 has this awesome percussive crunch that was very musical and maintained some of that even with rolling the volume down. I'm on the hunt for a majesty now.
 

Dr.Strangenote

Well-known member
Joined
Apr 27, 2010
Messages
888
Location
Yardley, PA
Drew, thanks for this explanation. I have not got my paws on one of these yet, so I cannot look at the wiring. My question is could one rewire this so that it is isolated from the signal? For example, if the battery drains and pressing the boost would simply cut the signal due to no battery or weak power source. I would find that a benefit in other applications, but that would just be my take on another practical use for a boost mode on, or no boost at all cutting (muting the sound).
 

beej

Moderator
Joined
Aug 16, 2004
Messages
11,302
Location
Toronto, Canada
I've done something similar in the past with another onboard preamp, where I wired a passive bypass switch. No idea how easy this is with the JP series, though I don't see why it would be any different. That said, all you would really gain would be a work-around for a dead battery, and you'd have to retrofit a switch for it (you wouldn't be able to use the boost switch, it would have to be something else). I don't really see it being worthwhile, myself.
 

drewbixcubed

Moderator
Joined
Jul 7, 2005
Messages
355
Location
San Luis Obispo
The preamp is always on, whether the boost is engaged or not. We have thought about implementing a "bypass" switch before in many of our products, but have not for a couple of reasons:

1. The instrument was sonically designed to have the preamp, so if the batter dies, it needs to be changed. Not to say the instrument wouldn't still sound good "passive," but that was not the design intent. Many instruments on the market today work this way....all of our basses have for 30+ years.

2. Depending on the design, it could take more components and/or cost to make the instrument work when the batteries die, than to make the preamp itself.
 
Top Bottom