Stingray Preamp Revelation - Interesting!

[Keith Guitars]

Posted this in Luthier's Forum, but thought I would run it
past y'all also:

Anyway - I was working on a recent EB/MM Stingray
with the 3-band EQ, and noticed this (surprising!) behavior:

I plugged in the bass, and quickly heard that the battery
was nearly dead. SO: contrary to the 'proper' approach,
I removed and replaced the battery without unplugging the
bass...

Now the interesting part - the bass still puts out signal
when no battery is connected!
All controls, including volume, are disabled...but the flat
pickup sound still comes out, even with no battery in the box.

On the plus side, this means that no active/passive option
would be necessary, since you'll always get *something*
out of the bass...

Actually, this is similar to something I've been thinking of
doing, which is to wire in a relay that would switch a bass
to passive when the battery goes below a certain voltage...
maybe this is what's going on here?

Anyway - thought this bore mentioning.

Peace,
Martin

[Figjam]

This is true for some stingrays, but not all. Some function with no battery, some dont. Not sure why.

[joeyl]

that's pretty cool.
figjam, any of yours do that?

[TrooperFarva]

My Sterling doesn't pass signal without a battery, and neither does my J-Retro in Active mode.

[WillPlay4Food]

My Bongo HH-4 put out no sound with the batteries unplugged.

[PilbaraBass]

hmmm...interesting...most preamps buffer the pickup signal before sending it through the tone circuits and then on to the jack...apparently this stingray does something different...and I don't know what....

it appears is that it somehow mixes the raw pickup signal with the preamp signal...but this doesn't explain why you can dial the volume completely off with a battery and not without a battery...very strange.

HEY!!! I just got a GREAT idea.... if you use a ganged volume pot and connect a passive pickup (w/ or w/o a passive tone control) to one side and connect the active circuit plus active EQ to the other side in a "blend pot" arrangement...you'll be able to dial in a blend between passive bass and active bass...

ohhhhhhhhh...how cool would THAT be?????

[tplyons]

My old Y2K Stingray did this so well, I contemplated having an active/passive switch installed.

[Salicete]

I just tried my MM SR-5, single pickup, less than 2 years-old.

Even odder than it working, or not working, I got a very weak signal from the "B" string with no battery, not enough to be playable, and nothing at all from the other strings.

I had hopes that mine would work sans-battery, as it would cover my rear on those occasions when I forget to bring extra 9-volts along to a gig, but no-go here either.

[Audere]

This would happen with lots of preamps...

If you play loud enough you might even be able to "power up" the preamp - the impulses at the start of the note would cause to front end protection diodes to turn on and drive the power supplies which would have some capacitance on them (hopefully) to keep the power "up" for a short period of time but normally the protection diodes do not turn on before 2 diode voltage drops.

There will also be some "leakage" paths through the parts when the power is not applied in which case it might work better if you keep the peak signal levels under 0.5 volts to not turn on any diodes.

You should expect lots of distortion and changing distortion levels with both input frequency and signal level etc.

[Keith Guitars]

Actually, the level and sound remain entirely consistent
with the 'flat EQ' active mode...no audible distortion,
and very usable volume.

I play extremely lightly, so I doubt I'm generating much
power with peaks in the playing...

My guess is that the Stingray circuit is somehow in parallel
with the dry sound?...EB tech support confirms that
certain Stingrays do continue to function as passive basses
after the battery is removed.

Hm.

Peace,
Martin

[dirtgroove]

Mine sounded like a p-bass to me.