Members petejt Posted August 26, 2009 Members Share Posted August 26, 2009 I really do not understand what "negative feedback" means in a guitar amplifier. What implications does it have on the tone, and amplification? Is more of it better? Less? Link to comment Share on other sites More sharing options...
Members Neilrocks25 Posted August 26, 2009 Members Share Posted August 26, 2009 It effects the tone, it like dark matter. But if you divide it by zero it can couse a vortex then in turn ending all life as we know it. Thats Metal And you dont want to know what happens if you boost it Link to comment Share on other sites More sharing options...
Members Dropsix Posted August 26, 2009 Members Share Posted August 26, 2009 It probably means less people will buy it Link to comment Share on other sites More sharing options...
Members sc4589 Posted August 26, 2009 Members Share Posted August 26, 2009 It's when it abuses its eBay account by pretending to be Nigerian and rich. Link to comment Share on other sites More sharing options...
Members PaoloJM Posted August 26, 2009 Members Share Posted August 26, 2009 It's when a sample of the output from the amp is feedback to some stage earlier in the amp, usually the phase inverter in push pull amps.It's called negative as it is feed to a stage so that it will be invertered compared to the normal signal at that point. It has the effect of reducing the gain and reducing the distortion produced in the power amp. The resonance and presence controls work to reduce the amount of this signal feedback in the low and high end, thus increasing low end and high end gain in the power amp.It also reduces the output impedance of the amp which has the effect of make the amp feel tighter and more controlled, as the amp will have tighter control over the speaker. Amps like most Voxes and most single ended amps don't have negative feedback in the power amp, and this is a big factor as to why the sound like they do. Negative feedback works works great in amps for rock and metal and it focuses the tone and make the amp feel tighter, no feedback well for blues as a looser feel sounds good for blues. Link to comment Share on other sites More sharing options...
Members MightyThor Posted August 26, 2009 Members Share Posted August 26, 2009 It's been a while but I'd like to add that negative feedback is used to stabilize high gain amps from oscillation. It kind of makes the amp self corrrecting before it goes into a non stable operating range. http://en.wikipedia.org/wiki/Negative_feedback_amplifier Link to comment Share on other sites More sharing options...
Members BusterBuster Posted August 26, 2009 Members Share Posted August 26, 2009 Negative feedback occurs when the output of a system acts to oppose changes to the input of the system; with the result that the changes are attenuated. If the overall feedback of the system is negative, then the system will tend to be stable. Cool copy and paste huh Link to comment Share on other sites More sharing options...
Members Tommy Horrible Posted August 26, 2009 Members Share Posted August 26, 2009 JVM = Lots of Negative Feedback Plexi = No negative feedback Link to comment Share on other sites More sharing options...
Members PaoloJM Posted August 26, 2009 Members Share Posted August 26, 2009 JVM = Lots of Negative FeedbackPlexi = No negative feedback Eh, no.... Link to comment Share on other sites More sharing options...
Members RyGy Posted August 26, 2009 Members Share Posted August 26, 2009 It is hard to say if more, or less negative feedback is a good thing. It will make it sound different, and can change the charactor the the whole amp. My Peters has a controll for dampening (feedback), and you can really hear the difference. Link to comment Share on other sites More sharing options...
Members newholland Posted August 26, 2009 Members Share Posted August 26, 2009 it's a function put in by amp designers that shuts the amp down if you happen to suck. they're working on one that'll actively berate the player, but that's a few years off. Link to comment Share on other sites More sharing options...
Members Eric Hellstyle Posted August 26, 2009 Members Share Posted August 26, 2009 that's what scammer amps get this and a paypal dispute Link to comment Share on other sites More sharing options...
Members Eric Hellstyle Posted August 26, 2009 Members Share Posted August 26, 2009 I can't explain what it is technically , but as a guitarist, I can say it affects the power amp tone A LOT it's a circuit that comes back from the speaker output to the phase inverterthis circuit usually has 3 basic stuff:- the negative feedback resistor- presence circuit- depth/resonance circuit all of them can be wired as variable controls or fixed valuesI guess I don't need to explain what the depth and presence do, but the negative feedback resistor alone (if it has a capacitor in parallel with it, then it's a fixed value depth/resonance) determines the amount of low end and power amp distortionlower values = higher negative feedback = cleaner, louder, dryer, more articulated power amp response, more peaky high endhigher values = lower negative feedback = growlier, deeper, smoother, less defined power amp response Link to comment Share on other sites More sharing options...
Members Zozobra Posted August 26, 2009 Members Share Posted August 26, 2009 As usual, Aiken holds the answershttp://www.aikenamps.com/NegativeFeedback.htm Link to comment Share on other sites More sharing options...
Members petejt Posted August 26, 2009 Author Members Share Posted August 26, 2009 Thanks for your help folks . I'll keep reading through it all and absorb it, so I can better understand what it means. The reason too why I bring it up, is that I've read that Negative Feedback is a key factor in Mesa/Boogie's Rectifier series amps. and since I want to get the Recto 2:100 poweramp, I'd like to know more about it. With the Recto, ANY Recto, is the Negative feedback increased/decreased in particular modes? Is that the difference between Orange Mode and Red/Modern Mode? Link to comment Share on other sites More sharing options...
Members petejt Posted August 26, 2009 Author Members Share Posted August 26, 2009 It is hard to say if more, or less negative feedback is a good thing. It will make it sound different, and can change the charactor the the whole amp. My Peters has a controll for dampening (feedback), and you can really hear the difference. So are you saying that increasing the Damping/Dampening LOWERS the negative feedback in the poweramp? Or RAISES the negative feedback? Link to comment Share on other sites More sharing options...
Members petejt Posted August 26, 2009 Author Members Share Posted August 26, 2009 higher values = lower negative feedback = growlier, deeper, smoother, less defined power amp response So are you saying that engaging the Modern Mode on a Recto, sets a higher capacitance, resulting in lower negative feedback and therefore the growlier, deeper, smoother less definied poweramp response you described?[/center] Link to comment Share on other sites More sharing options...
Members tommythelurker Posted August 26, 2009 Members Share Posted August 26, 2009 So are you saying that increasing the Damping/Dampening LOWERS the negative feedback in the poweramp? Or RAISES the negative feedback? Dampening doesn't change the feedback, feedback changes the dampening. The "dampening control" allows you to change the dampening by adjusting the amount of feedback. Link to comment Share on other sites More sharing options...
Members RyGy Posted August 26, 2009 Members Share Posted August 26, 2009 Dampening doesn't change the feedback, feedback changes the dampening. The "dampening control" allows you to change the dampening by adjusting the amount of feedback. Exactly. higher dampening = more feedback. On my Peters clockwise means less feedback. You can really hear the voice of the amp change when you move that knob. You can go from a smoother sound to a much more aggressive feel, and sound. My amp has a switch for resonance/dampening. I always leave it on dampening since I find that controll is more powerful. You can get more low end from the tone stack, eq in the loop, different speakers etc, but there is no external effect that can controll the dampening. from Peters Amplification website"A mini toggle switch below the Depth control allows this to be used as a "damping" control (when switched to the left), changing the overall amount of output damping. Less damping (clockwise) gives a more aggressive/deeper sound while more damping (counterclockwise) gives a softer/mellower sound. Using this control as a "damping" control makes it easier to tailor the response the amp achieves with different speaker cabinets, or to compensate for different acoustic environments. " Link to comment Share on other sites More sharing options...
Members Rear Naked Posted August 26, 2009 Members Share Posted August 26, 2009 it has to do with fragile harmonics and crystal lettuce. Link to comment Share on other sites More sharing options...
Members teemuk Posted August 26, 2009 Members Share Posted August 26, 2009 Link to comment Share on other sites More sharing options...
Members Ancient Mariner Posted August 26, 2009 Members Share Posted August 26, 2009 If you're not actually tweaking the amps design then I wouldn't worry about which have and don't have negative feedback. There are so many other variables to preamp and power amp design that this one is relatively insignificant when you're worrying about making the choice. Link to comment Share on other sites More sharing options...
Members blargh Posted August 26, 2009 Members Share Posted August 26, 2009 JVM = Lots of Negative FeedbackPlexi = No negative feedback wrong they both use negative feedback Link to comment Share on other sites More sharing options...
Members RUExp? Posted August 26, 2009 Members Share Posted August 26, 2009 JVM = Lots of Negative Feedback Plexi = No negative feedback Good one. Link to comment Share on other sites More sharing options...
Members again with this Posted August 26, 2009 Members Share Posted August 26, 2009 I knew this was 2:100 related. I don't remember what the manual says, but I think in the Rectos, it's all about engaging the Modern mode. Link to comment Share on other sites More sharing options...
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