Compressor, amp clipping...

Discussion in 'Amps and Cabs [BG]' started by Obsolex, Sep 8, 2003.

  1. Obsolex

    Obsolex Guest

    Nov 17, 2002
    Ok, I was wondering this about a compressor...
    I play fingerstyle on my amp sometimes at 3/4, or all the way up... And it clips when I slap and pop... I was just like, wondering if I got a compressor, would it make it not clip at those volumes??
  2. Mcrelly


    Jun 16, 2003
    Minnesota, USA
    if you set the compressor correctly it can drastically reduce sending a clipped signal into the input of the amp/preamp. however drastic settings can also take the life or 'punch' out of a guitar so if you get a compressor thats easily 'bypassed'. I have a "limiter" built into my SWR 350 and a limiter is actually a compressor set to activate only on extreme input signals. limiter when driven hard sound distorted, but is actually safe for amp section. "soft-knee" compressors can sound smoother and more natural than "hard-knee" circuits. you'll see some of this terminology when shopping for compressors. some companies have compressor and limiter pedals. I don't know who has the best. I had a tech21 bass compactor, but it was easily distorted for my taste.

    search for other "compressor" and "limiter" threads.
  3. Eric Moesle

    Eric Moesle Supporting Member

    Sep 21, 2001
    Columbus OH
    If you are running your amp 3/4 of its capability, the problem is insufficient power, and a compressor will do little to prevent clipping when you're already driving your amp way too hard.
  4. I'll have to follow Eric's lead and inquire as to wether or not you're clipping the power amp. If this is the case, more power might solve your problem. As far as my experience with compression goes I have a limiter built into my power amp (Peavey DPC1400X) that I leave engaged (on) and I also run an Alesis Nano-Comp in the effects loop of my pre-amp (set up as a "limiter", aka; hard-knee compression).

    By doing this I'm able to leave my master volume sections on my pre-amp rather high (about 4 o'clock on the SS side with my pre-gain anywhere from 10-12 o'clock) and run my amp full-out. I like a lot of clean head room and prefer to get volume and dynamics changes from my hands rather then screwing around with knobs.

    I only slap in a few tunes we do and this type of compression use works great. You can pick up an Alesis Nano-Compressor for $50 new at any GC. I use the "standard" rock bass setting in the quick set-up guide. The only adjustments I needed to make were to make sure the output level was equal to my unaffected signal (it has a bypass button). It doesn't affect the tone of my instrument in the least.

    Hope this helps:D
  5. Obsolex

    Obsolex Guest

    Nov 17, 2002
    No, well it's fine on fingerstyle up to just about any point... But when I slap/pop it clips at really really high volumes...
    What I'm asking is that since it's not clipping with fingerstyle, if I compressed it so the slap/pop would be as loud as the fingerstyle would it still clip??
  6. I'm a little un-clear as to what exactly you're asking. Your response of-

    -leads me to believe that you could still be underpowered. Without you answering a few questions it's hard to say. There are so many variables: The settings on your bass, the settings on the input stage of your amp, the output settings on your amp, what kind of amp and cab you're using, etc...

    I know from my own experience that running a compressor in the fashion that I do (which I described above) limits the transient peaks in volume that might otherwise go to my amplifier, causing the input (of the power amp) to clip or the opposite, causing the output (of the power amp) to excede what my cab can handle. IOW- it "evens out" the signal (actually it "cuts" it off at a certain point).

    Keep in mind that the settings I use are most likely different from your own, which is why I asked what kind of amp you're using, etc... You could get a compressor and set it up just like mine only to find out that you're overloading the front (pre) end of your amp or that you're underpowered and the output stage is still clipping. Let us know what you're working with and we can go from there!
  7. Obsolex

    Obsolex Guest

    Nov 17, 2002
    Yeah, with different settings there is different clipping peaks, ect... But here:
    Ok, say my amp is EQ'd like it is now...
    Master at 10, gain at 5-6 (half)...
    If at a certain EQ it clipped at 5-6 (half),
    only when I slapped and poppped. Would a compressor make it so that it didn't when I slapped and popped?
    Just an example...
  8. Sorry I didn't look at your signature and see what gear you're running. Don't I feel stupid! My best guess is that you're clipping the output stage of your power amp by asking more then what it can reasonably do. Your SVTIII Pro is only 450 watts, your cab suggests a 600 watt program (RMS). If you want to get louder without clipping you're going to need a larger, more powerful amplifier. Compression isn't going to help with clipping at the output stage of your amp. Simply put, you've run out of headroom. Sorry! Pick up an SVT4 Pro!
  9. Obsolex

    Obsolex Guest

    Nov 17, 2002
    Na, I love the sound I get out of this... Gigging (like everyone) I will run this through the PA anyway. I won't really need many watts for that, I mean, you can run a 25watt amp through the PA... But I don't want an SVT-4 because it is actually too many watts... It is 1600 at 4ohms, so I would only beable to use about 1/4, and I really don't wanna put a little too much out of my cab and blow the speakers up.
    The SVT-III is fine, no, MORE THAN FINE for practicing with, and i'll just run it through the PA when gigging...
  10. You should (at the VERY LEAST) put the amount of watts into your cab that it's rated for if you expect to recieve it's full potential (ie; maximum volume). Your cabinet can safely handle 2x's it's RMS rating (1200 watts) according to the Ampeg website. Using more wattage gives you what is known as "headroom". This basically means that your amp doesn't have to struggle as hard to produce lows, it's got all the power it needs.

    The amp I'm currently running is pushing 1400 watts into a cab with a 750 watt RMS rating and I have no issues whatsoever. This is where I use limiting and compression (just in case) to protect my speakers from transients. Even with a complete spike of the full output of my amp I'm still just under what the cab can endure (about 1500 watts). I have NEVER clipped my amp and I play weekly without PA support and can litterally FILL a room with bass.

    I was in no way implying that your amp is in some way "bad" or that you're doing something wrong. Just that you're asking too much from it and that is why it's clipping. If you continue to run things the way that you are though, you can actually damage your amplifier and speakers!

    You might want to ask more questions (possibly with a different post) about the effects of UNDER-POWERING speakers and amplifier clipping.
  11. Obsolex

    Obsolex Guest

    Nov 17, 2002
    I don't get it, I mean, Ryan Martinie runs an SVT-II (2) Pro into an SVT-810 (800 watts RMS)... Would't that be even worse??
  12. I'm guessing his sound is pretty distorted. Maybe that's what he wants (?). I read somewhere as well that he uses and additional amp and 4x12 guitar cab for mid's and highs. If you're trying to reproduce what you hear on an album you're in for a long trip. There are so many things that can be done to a signal during the recording process that there literally isn't enough room to type it all here. I have never heard them live but I think I can state with reasonable certainty that they have world class PA support. In that kind of a situation you don't even need an amp (in ear monitors, etc...). Also, what you hear coming out over the PA is likely the result of the FOH guys abilities and not the individuals gear. The sound of his gear might be DRASTICALLY different on stage.

    This is getting drawn out. What it boils down to is that you're clipping your amplifier. If you like that and think it adds to your tone then by all means do it! Different strokes for different folks is all it is I suppose...
  13. BruceWane


    Oct 31, 2002
    Houston, TX
    Tube amps are a whole different ball game. Sure, your SVT3 has a tube pre amp, but it has a solid state power amp. You can push a tube power amp into mild clipping and it'll get a little bit of grit -the classic "SVT Grind". It still sounds musical, and it won't damage the speakers. You cannot do this with a solid state power amp. Any clipping at all sounds bad, and it will damage speakers. There's a whole lot of technical stuff that explains why tube amps clip/distort differently than solid state amps, but just know that they are completely different designs that amplify sound in completely different ways.

    Basic Rule - you can clip a tube power amp a little bit; you cannot clip a solid state power amp AT ALL.

    I'd guess the next question is, "If tube amps have this advantage, why aren't more amps built that way".............

    They are expensive, and they are heavy. They also tend to have a somewhat less "hi-fi" sound, which some folks like, and some don't.
  14. Eric Moesle

    Eric Moesle Supporting Member

    Sep 21, 2001
    Columbus OH
    1. A compressor/limiter, when used PROPERLY, is only going to shave a tad of the transient peaks from your signal. If you use it to "squash" your sound completely - as you have stated to reduce your slap/pops to the exact same level as fingerstyle, then it is going to sound like crap, (IMO).

    2. Sounds like you are not underpowered for fingerstyle tones, but ARE underpowered for slapping at higher volumes. Slapping creates a greater load on an amp, and you'll need more oomph. If you turn your master down to a lower volume and you STILL hear distortion or breakup when slapping, you are clipping your preamp input and need to back that down. If the distortion abates when you turn the master down, then its evidence that you're not running enough power for your situation and you're asking too much of your amp.

    3. You have more likelihood of blowing your speakers by running your existing amp too hard than if you run 1500 watts into it at the same volume. Remember, with large amounts of wattage in reserve you have HEADROOM and don't necessarily USE that extra power, but its there to keep your output signal clean. Most speaker cabs can easily handle double their rated power, and will be happier than if you are stressing your existing amp to the point of clipping.

    4. Your existing cab will have no problem handling a 1500 watt head, and it will definitely sound better.
  15. BruceWane


    Oct 31, 2002
    Houston, TX
    Getting back to your original question.........

    A compressor will help keep your slap/pop from clipping your power amp. It will reduce the peaks in your volume that occur when you slap and pop. Although you probably ought to work on your technique a's real cool to look like your really slamming your fist into your bass, but it generally sounds like hell if you actually DO slam your fist into your bass. Try to get a good sound whille keeping your volume as even as possible - slap should not be way louder than your fingerstyle playing.

    But yes, a compressor will help a lot. They can be a bit tricky to use and understand, though. When you have a good compressor set properly, itseems like it has no effect on your sound; it tames the stray loud peaks so you don't sound uneven, and they can help you to get a bit more volume out of your rig by keeping the attack of your notes from clipping your amp. The trick is to not over do it. It's kinda strange to have a device that, when used properly, is not detectable.

    The ART Levelar is a nice, simple unit that sounds very good and has a very good price. Alesis has the NanoCompressor which is pretty cheap, and I've heard good things about them, but I have not ever used one. PreSonus makes a good compressor, and DBX pretty much set the standard for solid state compression, although we're getting up in price. Rane makes a split band compressor that is excellent for bass guitar, but again, that's getting more pricey. You'll find that compressors can cost well into thousands of dollars.

  16. True, but that's not because of the reasons you stated, IMO.

    If a speaker is damaged it received too much power. Period. Not because it is underpowered (if there is such a thing). It's the amp that is underpowered, because it is clipping. If the clipped signal stays under the maximum thermal power of the connected speaker cab, and the drivers aren't forced to move outside their mechanical limits, then the cab itself won't get damaged.
  17. Tim Cole

    Tim Cole

    Jun 12, 2002
    Findlay, Ohio
    Don't be fooled by amp power ratings, and volume settings. I was told when I owned my SWR bass 750, that with the gain properly set, and the master at 50%, I am getting my full 750 watts out of it at that point.

    A clip is in essence a power spike, which I have read can be 3-4 times the amps rated power. In other words, your 450 watt amp is capable of sending 1800 watts + to your 600 watt cab. DO NOT CLIP YOUR AMP! This will destroy speakers faster than anything. If you HAVE to be that loud, get a second cab, and a larger power unit.

    All you are doing now is abusing your gear.
  18. Joris- You are right.

    I think TC expained what I meant a little better as far as how he could damage his speakers by clipping his amp (ie; too much power).

    What it boils down to is that clipping is BAD!
  19. BruceWane


    Oct 31, 2002
    Houston, TX
    One of the main uses of compressors is to limit these spikes - more often called "transient peaks" - because they are very hard on all audio equipment. It's never a bad idea to have a properly set compressor in the signal chain (unless you've got a junk compressor that sounds bad, of course). From his description, he's only clipping on the attacks while slapping and popping, so a compressor would serve very well here.

    Extra wattage is never a bad idea either - understand that both a compressor and a larger amp serve to increase headroom. The compressor increases headroom by lowering the level of the highest peaks in the signal, while a larger amp increases headroom by raising the "ceiling" that the peaks are passing under.
  20. Bob Lee (QSC)

    Bob Lee (QSC) In case you missed it, I work for QSC Audio! Gold Supporting Member Commercial User

    Jul 3, 2001
    Costa Mesa, Calif.
    Technical Communications Developer, QSC Audio
    Not necessarily; it'll still be related to what you're putting through the amp. For example, if you're not playing, but have your bass muted, you're getting close to zero watts, even if the amp is turned way up. You won't actually get zero because of noise and hum, but I would hope that would be very minimal.

    Typically, clipping falls somewhere more than equal to, but less than double, the amp's power rating. Speaker damage is caused by too much power (resulting in too much heat) or too much power at too low a frequency (resulting in overexcursion, causing mechanical damage), but not by clipping in and of itself. For example, you could drive a 50-watt amp into severe clipping, and it won't damage a speaker rated to take 500 watts continuously, but it sure won't sound good, either.