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how do I de-activate an active input?


snydley

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Hey Snydley - need to clarify a wee bit. Assuming we're talking 'bout a head here and we're talking 'bout needing another passive input I would suggest adding another passive rather than de-activating your active input.

"He is to music what Stevie Wonder is to photography." getz76

 

I have nothing nice to say so . . .

 

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And why would you want to do that?

 

You really should only be plugging one bass at a time into an amp. It's not that hard to plug and unplug.

 

If you want to keep everything plugged in so you can switch basses quickly, you probably should use some sort of switch or mini-mixer.

 

The active input probably has a resistor to make it a little softer than the passive input. Active instruments are usually a little hotter so the input is "padded" to keep from distorting the preamp.

 

I suppose you could just remove the resistor. Look inside the amp at the input jacks. Is there a resistor wired into the active jack? You could just clip the leads. And of course void the warranty and let the magic smoke out of the amp. :freak:

 

Don't tell anyone that I advised you to do this, I would never do anything like that, I've ruined enough gear with my experiments over the years. :D

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Like Jeremy said.

 

The "active" input on most amps is just padded so some degree because the output of an active bass tends to be much hotter than a passive bass. It shouldn't make a difference to you while you are playing.

 

I use the active/passive inputs on my preamp depending on which bass I'm playing. When switching basses during a gig, I know exactly how much to turn the preamp gain up or down depending on which bass I'm using and whether or not it's active or passive. That seperate gain input can be your best friend.

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What if you decide one day to sell the Hartke to move on to better equipment? Modifying your amp this way can cost you a couple of Ben Franklins on the used market.

 

For now just get a small mixer or an A-B pedal switch ($30-80) and run that into your passive channel. If you can spend a little more, there's some great mixer/preamps out there.

Don't mod your amp unless you plan to keep it or pass it on to your children. (very unlikely options for a Hartke, IMHO)

:wave:

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You could get the input changed to an unpadded instrument level input, but it would probably be a more expensive mod than simply buying an active mixer like this one:

 

http://www.raven-labs.com/art/products/mdb1/smallmdb1.jpeg

 

Or buying a simple A/B switching box like this one:

 

http://media.zzounds.com/media/fit,325by400/quality,85/brand,zzounds/selector-d6c4951797a62f2889be1b5a52991f83.jpg

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To add eaither another active or passive input: It all depends on how labor and knowledge intensive the mod would be. If it's not directly on a PCB it's actually pretty easy to parallel an existing jack. If it's on a PCB one should probably have the schematic just to make sure they have properly traced the connections.

 

Usually 'taint no big thang.

.
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Maybe I'm overthinking this but I thought that on some amps the difference between passive and active input is not just of sensivity but also of impedance. For instance on my SWR GP:

 

Passive/Active Input Jack = 800K ohms

Active Input Jack = 60K ohms

Gain @ 1KHz

Passive/Active Input Jack = 71.4

Active Input Jack = 14.3

 

Can changing a resistor affect the impedance and gain so drastically?

 

Alex

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A company that would use just a resistor to make the difference would be

 

(1) cheap.

(2) not so concerned with sonic integrity for that particular product. Ever use a passive mixer?

 

With all the bushwah I hear about active circuity, it just flat out trounces passive circuitry for almost any application where good s/n and linear reproduction/preservation is the goal.

.
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To add eaither another active or passive input: It all depends on how labor and knowledge intensive the mod would be. If it's not directly on a PCB it's actually pretty easy to parallel an existing jack. If it's on a PCB one should probably have the schematic just to make sure they have properly traced the connections.
- 14130

"He is to music what Stevie Wonder is to photography." getz76

 

I have nothing nice to say so . . .

 

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Oops.

Anyway, to simplify that quote a little if you are determined to do this -

 

Open up your head and if the active input jack has wires attached to it cut 'em and tape 'em really well. Now solder jumpers from that jack to your passive that you are duplicating making sure you go from tip to tip and sleeve to sleeve.

 

If the jack is directly attached to a board, forget it. Way to easy to screw it up.

"He is to music what Stevie Wonder is to photography." getz76

 

I have nothing nice to say so . . .

 

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If my post wsn't simple enought ot understand for the person wanting to do this, they probably shouldn't bother ; }

 

Anyway, I wouldn't use either existing jack to duplicate the other. You might want that functionality around still. I would instead ADD a jack wherever spare panel space is available. I've often used the rear panel for this.

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No offense intended, but this has me seeing red flags. First off, why do you want to deactivate an active input? Tell us what you're trying to actually accomplish, and I'm sure someone here will know several possible answers. I always find that if I pair up with a couple of other folks, I have access to a whole brain then... :freak:

 

L8r,

Dave

Old bass players never die, they just buy lighter rigs.

- Tom Capasso, 11/9/2006

 

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I agree - get a mixer of some sort if you need to have two passive things plugged in at the same time.

 

My guess is that snydley has some low-volume application where the requirement is two different passive instruments (bass and guitar). Because of the padding on the active jack, the instruments are difficult to balance that way. That's why a mixer (even an inexpensive one) will serve the need quite well.

 

If it's something else, maybe snydley suffers from whiplash :D:eek::rolleyes::cool:

(sorry snydley - couldn't resist - I never can...).

 

BenLoy - that Raven Labs thing is top shelf. Except that the company is going out of business so they may be hard to find. FYI - they are staying "active" enough to honor warranty service needs. I'd expect nothing less than a class guy like Steve Rabe.

 

Tom

www.stoneflyrocks.com

Acoustic Color

 

Be practical as well as generous in your ideals. Keep your eyes on the stars and keep your feet on the ground. - Theodore Roosevelt

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