Modifications to increase a preamps headroom?

Kwesi · #1 08-21-2010, 05:03 PM

Is it possible to increase the amount of headroom a preamp has? I really like my Promethean but my basses signal is really hot and in combination with the way I play I'm seeing the clip light waaaaaay too much for my tastes. Any suggestions besides changing the way I play are welcome.

bongomania · #2 08-21-2010, 05:27 PM

Are you just seeing the clip light, or are you hearing clipping as well? And have you tried turning down the input gain knob on the amp?

Kwesi · #3 08-21-2010, 05:30 PM

Quote:

Originally Posted by bongomania

Are you just seeing the clip light, or are you hearing clipping as well? And have you tried turning down the input gain knob on the amp?

Seeing it often and hearing it occasionally. If I turn the Gain down I have to turn up the Master to compensate for the loss in volume so I end up clipping anyway. I've tried all manner of combinations between the Gain and Master levels and I'm still clipping often on the output and occasionally on the output when the band is crankin'. I have the volume I want but I can't get there without clipping the amp.

bongomania · #4 08-21-2010, 05:49 PM

Oh that's right, I forgot we already answered this one for you in a previous thread. Never mind.

Kwesi · #5 08-21-2010, 05:50 PM

Quote:

Originally Posted by bongomania

Oh that's right, I forgot we already answered this one for you in a previous thread. Never mind.

Not exactly, which is why I posted this thread. Though I guess I could have just put the question in the other one.

Jazzdogg · #6 08-21-2010, 06:00 PM

What happens if you turn down the volume on your bass, or lower the pickups slightly?

fdeck · #7 08-21-2010, 06:39 PM

If you are clipping the output stages of an amp, then your amp isn't powerful enough or you need to educate the rest of the band on volume levels.

billfitzmaurice · #8 08-21-2010, 06:54 PM

Quote:

Originally Posted by Kwesi

Is it possible to increase the amount of headroom a preamp has?

No as that's a product of the voltage swing capability of the pre-amp, and there's no way to change that other than major surgery.

Kwesi · #9 08-21-2010, 07:12 PM

Thanks bill, that's pretty much what I was looking for. One last question. If I'm getting the clip light but not hearing any clipping is it all good?

fdeck · #10 08-21-2010, 07:13 PM

Quote:

Originally Posted by Kwesi

Thanks bill, that's pretty much what I was looking for. One last question. If I'm getting the clip light but not hearing any clipping is it all good?

If it sounds good, then no harm is being done. The clip light might be set up as an "early warning." Also, a small amount of clipping is not necessarily objectionable.

Kwesi · #11 08-21-2010, 07:18 PM

Quote:

Originally Posted by fdeck

If it sounds good, then no harm is being done. The clip light might be set up as an "early warning." Also, a small amount of clipping is not necessarily objectionable.

I see! Maybe I can hold onto it afterall, thanks a bunch.

KramerBassFan · #12 08-21-2010, 09:00 PM

Get a bigger more powerful/bigger amplifier.

And don't worry about the clip light.. until you hear it.

naturalkinds · #13 08-21-2010, 09:34 PM

Quote:

Originally Posted by Kwesi

I have the volume I want but I can't get there without clipping the amp.

Huh? If you have to get the volume you want by clipping the amp, then you don't really have the volume you want, unless you want a clipping amp, which you don't, ergo, this can't be true.

SurferJoe46 · #14 08-21-2010, 11:34 PM

Quote:

Originally Posted by naturalkinds

Huh? If you have to get the volume you want by clipping the amp, then you don't really have the volume you want, unless you want a clipping amp, which you don't, ergo, this can't be true.

Even after my latest dose of Vicadin, that makes sense.

Kwesi · #15 08-22-2010, 12:14 AM

Quote:

Originally Posted by naturalkinds

Huh? If you have to get the volume you want by clipping the amp, then you don't really have the volume you want, unless you want a clipping amp, which you don't, ergo, this can't be true.

Haha, yea I could have worded that better. It's like this: My amp has the volume I need and I can get the volume I need but when I'm up there I'm constantly clipping. I just want the headroom to not clip when I'm playing really loud. But from what I'm seeing in the thread I might not have to worry about it since I'm only seeing the clip light not hearing the amp fart out on me.

naturalkinds · #16 08-22-2010, 06:48 AM

Headroom doesn't clip. A *signal* clips.

You won't get much sympathy here for worrying about a clip light if you are happy with everything else about your amp's performance. Many amps have a signal/clip light that comes on when a note is played and the gain level is optimally set to just below digital clipping. That's not that weird. In fact, the Glockenklang Heart-Rock does this a lot. Don't think that every amp is designed the same way; I doubt, for instance, the Ibanez is set up like your old LMII. Think of the light as being there to give you *information* on the incoming signal; you can either freak out at it -- if you know it's going to entail that your signal is digitally clipping -- or you can not freak out at it -- if you can hear that your signal isn't actually digitally clipping.

Get a Sharpie and colour it in if it's really freaking you out.

You're probably a good candidate to read up on some various audio engineering FAQs having to do with gain staging. It sounds to me like you are fundamentally misunderstanding concepts required to make sense of things like 'headroom', 'dynamic range', 'unity gain' and so on. Not a big deal, but I doubt there's much more anyone can say in this thread except 'don't worry, man'.

Aram · #17 08-22-2010, 06:53 AM

Quote:

Originally Posted by Kwesi

Is it possible to increase the amount of headroom a preamp has? I really like my Promethean but my basses signal is really hot and in combination with the way I play I'm seeing the clip light waaaaaay too much for my tastes. Any suggestions besides changing the way I play are welcome.

What about running a compressor in your signal chain? You might experience less clipping that way, and get more usable headroom out of your amp.

I've had a lot of luck with the EBS MultiComp. Very subtle (as a compressor should be), and I've gotten a lot of crappy backlines working a lot better with the MC between my bass and the amp.

georgestrings · #18 08-22-2010, 09:36 AM

Quote:

Originally Posted by Aram

What about running a compressor in your signal chain? You might experience less clipping that way, and get more usable headroom out of your amp.

Was thinking the same thing...

- georgestrings

BassmanPaul · #19 08-22-2010, 10:24 AM

Quote:

Originally Posted by Kwesi

Seeing it often and hearing it occasionally. If I turn the Gain down I have to turn up the Master to compensate for the loss in volume so I end up clipping anyway. I've tried all manner of combinations between the Gain and Master levels and I'm still clipping often on the output and occasionally on the output when the band is crankin'. I have the volume I want but I can't get there without clipping the amp.

Then it's simple: You need a bigger amp and the speakers to handle that power.

Paul

KJung · #20 08-22-2010, 01:34 PM

Quote:

Originally Posted by Kwesi

Seeing it often and hearing it occasionally. If I turn the Gain down I have to turn up the Master to compensate for the loss in volume so I end up clipping anyway. I've tried all manner of combinations between the Gain and Master levels and I'm still clipping often on the output and occasionally on the output when the band is crankin'. I have the volume I want but I can't get there without clipping the amp.

I think you are confused about how this all works. There is preamp clipping and there is power amp clipping. In all but the most extreme situations, turning down the gain on the preamp will eliminate all issues with preamp clipping. In highly unusual situations (super heavy technique or a bass with massive output) you might have to pad the input gain by using either the active input or the pad switch (if there is one).

Setting the preamp gain correctly and then adjusting/compensating for volume with the master is what you are supposed to do. However, if you have your preamp gain set correclty and still hear clipping, then it is either the power amp being driven too hard, or your speakers reaching their limits.

There is no reason to either assume clipping is coming from the preamp, nor to 'modify' a preamp that has a gain control.