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Alembic Club » Alembic Basses & Guitars » Archive: 2007 » Archive through September 24, 2007 » Active or Passive? « Previous Next »

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Username: willride3

Post Number: 27
Registered: 3-2005
Posted on Monday, August 20, 2007 - 11:13 am:   Edit Post

O.K. Here we go with a question... At input on an amp, is the Alembic Bass to be padded as active, or I remember incorrectly that the pickups and electronics operate on an unpadded input? Thanks for clarification.. They sound great either way, just want the most out of them. Thanks from Detroit, Michigan.....Willride3
Username: willride3

Post Number: 28
Registered: 3-2005
Posted on Monday, August 20, 2007 - 11:15 am:   Edit Post

They are... Essence and Epic models running on a single 9 volt battery, thanks again.
Senior Member
Username: olieoliver

Post Number: 1525
Registered: 2-2006
Posted on Monday, August 20, 2007 - 11:44 am:   Edit Post

Either one should be OK. The padded input won't be as hot as the normal input. You just have to make sure you aren't clipping the signal when you run it thru the passive input.

I play my through the passive (non-padded) input normally on my SWR but through the active input on my Eden combo.
Advanced Member
Username: dfung60

Post Number: 268
Registered: 5-2002
Posted on Tuesday, August 21, 2007 - 8:36 pm:   Edit Post

The "pad" in the preamp input is a resistor that reduces the gain/sensitivity of one of the inputs. The reason you want lower gain is in the event that instrument you're plugging in has too high an output level for the regular input. The amp designer wants to design in enough gain so a low-output bass produces enough signal to drive the power amp to full output. If you have a lot of input gain AND a high output bass, you run the risk of overdriving the preamp.

So, the answer for you is to turn up the volume on your bass, turn the preamp gain up (if you have one) and see whether you get a clean sound. If you get distortion, then try the padded input and see if that sounds cleaner and that you can still drive your rig to full volume.

Alembics are all active, and generally there's a trimpot in the control cavity that lets you adjust the output level over a wide range. If you play multiple basses, you may find it easier to dial back the Alembic's output so it's closer to your other instruments.

Because of the active electronics of your Alembic, you can crank the output level up and down without affecting the tone (try turning down the output level on a passive bass and you'll lose treble).

There's an interesting psychoacoustic effect where everything sounds better when it's louder (just like your drummer always told you), so it never sounds good when you turn down the output level or used the padded input, but it really will sound better when you're not doing an A/B comparison.

David Fung
Senior Member
Username: 811952

Post Number: 1116
Registered: 10-2003
Posted on Wednesday, August 22, 2007 - 8:23 am:   Edit Post

On some instruments, the input impedance will really color the tone of the instrument. Last weekend I played my brother's electric upright (a Chinese NS-design WAV) for the better (or at least more strenuous) part of a set. Plugged into the standard input of my Ampeg, the low end was simply gone. Plugged into the padded input the bass sounded good with lots of warm bottom.

But, yeah, the Alembic doesn't seem to care what it's plugged into, although some amps might feel differently if you've got your output on the bass cranked higher than they are expecting.

Senior Member
Username: byoung

Post Number: 744
Registered: 12-2004
Posted on Wednesday, August 22, 2007 - 2:41 pm:   Edit Post

Piezos are especially sensitive to input impedance.
Advanced Member
Username: terryc

Post Number: 239
Registered: 11-2004
Posted on Thursday, August 23, 2007 - 3:34 am:   Edit Post

David..there was a mod that you can do to telecasters/strats, fit a treble bleed capacitor over the vol pot to reduce the treble loss when you lower the volume at the guitar..It should work on a passive bass..sorry cannot remember the value but if you play Alembics there is no need for this!!!
Senior Member
Username: 811952

Post Number: 1117
Registered: 10-2003
Posted on Thursday, August 23, 2007 - 6:14 am:   Edit Post

I had a Jazz Bass years ago that had the capacitor mod, and it sounded unbelievably good. I later modded a couple of basses with push/pull tone knobs, taking the entire tone circuit out of the signal path, and it the change in tone was equally stunning..

Then I ordered an Alembic... ;)

Intermediate Member
Username: oujeebass

Post Number: 104
Registered: 10-2002
Posted on Sunday, August 26, 2007 - 9:17 am:   Edit Post

What about when your running through effects? What input would be applicable then?
Senior Member
Username: 811952

Post Number: 1119
Registered: 10-2003
Posted on Sunday, August 26, 2007 - 5:22 pm:   Edit Post

Whichever input gives the most gain (or least pad) without distortion would be the one I would use.
Senior Member
Username: bracheen

Post Number: 1259
Registered: 11-2003
Posted on Monday, August 27, 2007 - 6:22 am:   Edit Post

The only time I've noticed a difference on my amp is when plugging a passive bass into the active jack. The active basses sound the same either way.

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