Members scolfax Posted July 15, 2008 Members Share Posted July 15, 2008 I have a switch on the back of my old Ampeg guitar amp that can either be set for High or Low Damping. What's this supposed to be for? Link to comment Share on other sites More sharing options...
Members newholland Posted July 15, 2008 Members Share Posted July 15, 2008 damping is the ability of an amp to 'hold' a speaker-- basically, more = tighter bass, less= more 'sag'... in a nutshell. Link to comment Share on other sites More sharing options...
Members scolfax Posted July 15, 2008 Author Members Share Posted July 15, 2008 Thanks for the reply. So High Damping should give me tighter bass? Link to comment Share on other sites More sharing options...
Members teemuk Posted July 15, 2008 Members Share Posted July 15, 2008 http://www.aikenamps.com/NegativeFeedback.htm Link to comment Share on other sites More sharing options...
Members newholland Posted July 15, 2008 Members Share Posted July 15, 2008 it should snug it up a bit. it's not really related to negative feedback, to my knowledge-- that's generally a circuit that 'compares' input to output to cut down on distortion generated by the amp. usually- negative feedback is controlled by the 'presence' circuit-- if i'm not mistaken. here's a def. from wikipedia-- Explanation In loudspeaker systems, the value of the damping factor between a particular loudspeaker and amplifier, describes the ability of the amplifier to control undesirable movement of the speaker cone near the resonant frequency of the speaker system. It is usually used in the context of low frequency driver behavior, and especially so in the case of electro-dynamic drivers which use a magnetic motor to generate the forces which move the diaphragm. Speaker diaphragms have mass, and their surrounds have stiffness. Together these form a resonant system and the mechanical cone resonance may be excited by electrical signals (eg, pulses) at audio frequencies. But a driver with a voice coil is also a current generator since it has a coil attached to cone and suspension and that coil is immersed in a magnetic field. For every motion the coil makes, it will generate a current which will be seen by any electrically attached equipment, such as an amplifier. In fact, the amp's output circuitry will be the main electrical load on the 'voice coil current generator'. If that load has low resistance, the current will be larger and the voice coil will be more strongly forced to decelerate. A high damping factor (which requires low output impedance at the amplifier output) very rapidly damps unwanted cone movements induced by the mechanical resonance of the speaker, acting as the equivalent of a 'brake' on the voice coil motion (just as a short circuit across the terminals of a rotary electrical generator will make it very hard to turn). It is generally, though not universally, thought that tighter control of voice coil motion is desirable as it is believed to contribute to better quality sound. A high damping factor indicates that an amplifier will have greater control over the movement of the speaker cone, particularly in the bass region near the resonant frequency of the driver's mechanical resonance. However, the damping factor at any particular frequency will vary, since driver voice coils are complex impedances whose values vary with frequency. In addition, the electrical characteristics of every voice coil will change with temperature; high power levels will increase coil temperature and so resistance. And finally, passive crossovers (made of relatively large inductors, capacitors, and resistances) are between the amplifier and speaker drivers, and also affect the damping factor, again in a way that varies with frequency. For audio power amplifiers this source impedance Zsource (also: output impedance) is generally smaller than 0.1 ? (ohms), and, from the point of view of the driver voice coil, is a near short-circuit. The loudspeaker's load impedance (input impedance) of Zload is usually around 4 to 8 ? although other impedance speakers are available, sometimes as low as 2?. Link to comment Share on other sites More sharing options...
Members scolfax Posted July 15, 2008 Author Members Share Posted July 15, 2008 The Ampeg has a presence knob right next to the damping switch. Without looking at it I think the presence setting is only active when damping is set to high. Does this make sense? Here's what brought this up. I play in my garage with the combo flat on the floor - and I stand pretty close to it. I thought my settings were pretty good. Then I played at a friend's garage with an amp stand for the first time. Everything sounded horribly bright and I couldn't tone it down with the preamp settings. Finally I remembered that switch and knob and changed it (flipped the switch and twisted the knob) without looking at it and it solved my problem. Link to comment Share on other sites More sharing options...
Members newholland Posted July 15, 2008 Members Share Posted July 15, 2008 i'm not sure-- what's the amp? it's POSSIBLE that that's the case-- it could some sort of switch between a pot and a static resistor in the output section-- but that's pretty outside my realm.. i am NO amp designer! EDIT-- is it a vt60 or something? Link to comment Share on other sites More sharing options...
Members scolfax Posted July 15, 2008 Author Members Share Posted July 15, 2008 i'm not sure-- what's the amp?it's POSSIBLE that that's the case-- it could some sort of switch between a pot and a static resistor in the output section-- but that's pretty outside my realm.. i am NO amp designer!EDIT-- is it a vt60 or something? Close! It's a VT-120 12" combo. BTW, thanks for your replies! Link to comment Share on other sites More sharing options...
Members teemuk Posted July 15, 2008 Members Share Posted July 15, 2008 At least in the Ampeg VT-120 the damping control is a switch that simply shunts most of the (negative) feedback signal to ground. When negative feedback is in such manner decreased the amplifier Link to comment Share on other sites More sharing options...
Members newholland Posted July 15, 2008 Members Share Posted July 15, 2008 that's pretty cool how it all works together- negative feedback also has some sorta detrimental effects on sonics-- so noodle around with it and see what happens. i know in my own amp- with the neg. feedback all the way up (presence all the way down), the top end goes fairly flat, and harmonics are just not nearly as 'breathy'. i basically turn mine about off.. course, it effects bass by being mushier.. but i kinda like that. nice call teemuk-- cool how it all works together. no prob scolfax.. glad to try and help. Link to comment Share on other sites More sharing options...
Members wanky Posted July 15, 2008 Members Share Posted July 15, 2008 less damping will give you more bass dynamics and a deeper thicker tone and feel more will offer a brighter, more aggresive, cutting, clear and more defined tone when in doubt go with more damping, tighter tone tends to sound better Link to comment Share on other sites More sharing options...
Members scolfax Posted July 15, 2008 Author Members Share Posted July 15, 2008 I must have had damping on High, with the presence all the way up - the overall tone was pretty piercing, which was not good for nailing that "Black Magic Woman" tone. Link to comment Share on other sites More sharing options...
Members mseriously30 Posted July 15, 2008 Members Share Posted July 15, 2008 You've confused the "damping" switch with the "suck" switch. Don't ever turn that one on... Link to comment Share on other sites More sharing options...
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