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Discussion in 'Pickups & Electronics [BG]' started by cassius987, Apr 10, 2010.
I just heard that certain buffers can hurt input stages of preamps.
What could lead to this?
It's just a GIF file. There must be an issue with your computer with viewing images.
it must be the office's firewall or something, here at home I can see them all.
> I just heard that certain buffers can hurt input stages of preamps.
Hm. Makes no sense to me, either. In theory a buffer is a unity-gain circuit with a high input impedance (less loading of the pickup) and low output impedance (better to drive the cable and the amp's input while hopefully reducing noise susceptibility). I can't see how that could cause a problem, unless either the design or execution were wrong. A few possible real-world "gotchas" come to mind, but who knows...
No, its a myth.
The worst a buffer can do--if it has gain-- is clip the amp's preamp. I had my buffers set for almost line level and it never hurt any of the amps I used, but i was able to clip Eden amp's preamps quite easily.
But amps have active and passive inputs for a reason, though I always use the passive inputs even with active basses.
Thanks for the info!
For a couple years in the early 1980s my main axe was an SD Curlee that the previous owner had removed all the electronics from (and, btw, glued pennies over the now-empty knob holes, which looked really cool w/ the brass & gold hardware). Nothing but wire between the DiMarzio pickup & the output jack.
I hated it.
I find that A) if there's no volume control I at least like to have a Kill Switch on my instruments so I can mute it between tunes, or when taking a break, or during tacets; and B) for my jazz & experimental gigs especially, I like to have fingertip volume control for additional expressive color and/or wider dynamic effect.
Well here's a report back.
I took the bass to rehearsal with the goal of using both the preamp and the passive/no controls setup and comparing. The main thing I noticed using the passive setup, with a 10' cable and an Ashdown ABM EVOII 500 head into a 151R Markbass cab, was that the tone was beefier than before all around and actually a little more difficult to tame. The Audere wasn't really doing much for me either though so I stuck with the passive mode. The band thought it sounded fine. When I got the recordings back the main thing I noticed was that my attack sounded crisper, it wasn't as washed out, and that some of the absolute highest harmonics were getting through in a way they hadn't before. But compared to previous practices it was not a huge improvement or downgrade, just different.
Ultimately I wanted to keep the "no load" tone but have options to bleed off treble or blend the pickups so they don't comb filter so I made a passive harness that has four controls and a Switchcraft switch and the ROS/mono setup so it looks dead stock from above. It's Bass Volume 500K (I attenuate this pickup when blending), a DPDT push-pull switch to use the variable Vintage Tone Selector that was introduced in 2006, and a pair of Fender No-Load pots for the tone controls with 0.022 uF caps. I think this strikes a good balance for me and I'll report on it after next rehearsal.
I build in the option when I can talk a customer into it.
This will be hard to see but;
What is shown is a volume and tone and switch per pickup - the switch takes the pots out of the circuit.
With volume rolled to off the switch is a kill.
For what it's worth I've been playing around a lot in GarageBand and I really like the wiring harness I came up with. Hopefully can get a rehearsal going tonight to hear it through the amp/cab.