#1 Well. I've got a quite crappy amplifier and when i send boosted or overdriving (strong) signals into it i get it to be alot louder then it normally is.
This got me thinking if the amp has to "work" harder and might burn out if i send too strong a signal into it.
I realize this might break the speaker or speaker elements but what im interested in is the "amp section".
#2 What makes a effect pedal "safe" to use. Any routines you guys have to test a pedal before connecting it to an amp?
The first thing I do when a circuit is done is to test it before adding the stomp switch, so I know it works and later problems are in that wiring. I check between output and ground for any DC present (output caps block it, solder bridges can defeat that!). DC ain't so good for your amp!
After that, I hook up to an old marshall ss 10W practice amp I have. If I kill it, I won't feel bad. When it passes that test, it can go before my tube amp.
Theoretically, you could pump so much juice into your amp input that you could toast something. I don't know what that level is, though. I've heard it said that up to 5-7 volts on the input won't cause problems, but don't quote me!! Depends on whether it's tube or SS, too. The most I really have run into my input is around 3 to 5V (ac), with no bad results.
http://www.monstereffects.net/GuitarWorld.jpg
I would say, no.
Or at least, if you do, it's not the fault of the pedal as such, it's the fault of having the amp turned up too high for the input.
In which case, you might say that some pedal makes it POSSIBLE to damage the amp, but the damage is done by the idiot using the amp.
you'd like to think the amp would have enough protection on its input, so that you couldn't kill it just by overloading the input. Don't know if all of them do though.
"Loud" = more current passing somewhere. If the component is equipped to handle that heat, groovy. If not, poof! Even though your focus is on feeding an amp a hot, hot, hot signal as a result of a booster/distortion of some kind, the input stage is not the only part to be affected. One has to distinguish between:
a) The speakers and how much current/wattage they can handle, both continuously and in terms of instantaneous peaks. Managing those peaks successfully is one of the reasons for the existence of limiters, since a cone moving too far too fast for its voice coil is not a problem restricted to guitar amps, but P.A. systems too. Note that some amps have a small margin of "safety" as regards speakers (e.g., one or more speakers rated to handle maybe 20% more power than the amp itself is rated to deliver) while others may have a much wider margin of safety (e.g., 2 speakers rated at 100W capacity@ on an amp rated at 45W output capability).
b) The output transformer (if a tube amp, though some older transistor amps will have interstage transformers). Transformers are also rated in terms of current-handling capability, and you will sometimes see comments in passing about "upgrading" the output transformer on amplifier X to handle more wattage, or about the output transformer in amplifier Y being insufficient. Whatever current is not effectively handled gets turned into heat, and at that point the transformer changes into just another piece of wire that go "Poof!" just like another well-known piece of wire - the fuse.
c) Individual semiconductors or tubes. Again, repeated heat build-up can, over time, reduce the lifespan of a component that is expected to handle large current. That's why some tube amps have fans near the power tubes, and it is also why power transistors and chips are mounted on heat sinks.
d) The circuit structure itself. Admittedly, this one is the rarest. The first personal computer I bought almost 25 years ago, to the day, was one of those all on one board affairs, including the on-board voltage regulation. Unfortunately, the regulator was not properly heat-sinked, and within a relatively short period (<year), a crack or two had occurred in the traces on the board and the thing would not boot unless I pointed a hair-dryer at it, caused the metal traces to expand slightly and eventually make contact so that the ROM could be read. Thankfully, the traces on an amp's PCB are generally thicker and wider than those found on a computer PCB, so the risk of heat-caused fracture is much lower, but the same principle applies: if the amp is forced to run hotter, then anything which is susceptible to heat-related stresses is vulnerable.
Of these 4, speaker damage (and ear damage :icon_eek:) is probably the only one that could occur as a result of a single power chord at juiced-up volumes. Maybe not quite the same way it occurred in "Back to the Future", but with the same negative consequences for the speakers.
I suppose one of the ways to assure that none of this ever happens is to use under-rated fast-blow fuses so that power is removed before the point of no return. So, if the amp wants a 6A slow-blow, use a 4A fast-blow. That will keep you tame enough.
My bass player cooked the preamp on his rig by pushing a bunch of extra signal into it with an EQ. But I've heard bass amps arent designed to have all kinds of effects and crap coming at them. I could be wrong.
It can happen, just not often. My stereo amp at home has separate fuses for the preamp and the power amp, so I'm assuming this is in anticipation of something that is a realistic possibility.
When I was a kid I destroyed the phono in on my stereo buy feeding it an active bass.
We were kids! We wanted to jam but no amps. It was usually fine with a regular guitar but that extra bit of push from the active pickups killed it.
I also got pretty weird results using a Red llama into an 80s solid state amp.
Waaaaay to much boost for that puppy. Went a bit awol tone wise for a some time.
Took a while to settle back down. I've never cracked it open to see whats going on in there, but in my experience, yes, too much input boost with a SS can stuff things up nicely.
I think GibsonGM's comments above are good advice.
Not to be a doubting Thomas (apologies to all the Thomases, it's just an expression), but we keep hearing all these stories that begin "I destroyed/broke/fried my...", and we never ever hear exactly what it was that was put out of action. Naturally, these are exactly the sorts of folk legends and nonspecific testimonies that prompted the original question in this thread. Doesn't mean it didn't happen. It simply means that without details, the naive listener is free to confabulate whatever %^&*amamie explanation and mythology they want, like "Fuzz boxes will destroy your amplifier".
There are LOTS of reasons why an amplifier malfunction could co-occur with a hot input signal. In the absence of followup diagnostic info (was it a speaker? a transformer? a diode in the PS? an input resistor? an under-rated cap in the signal path?), it is difficult to know what sort of advice to provide.
Keep in mind there is one sort of "explanation" for budget amps that cut corners in production costs and use components at the margins of their ratings, and another set of explanations for professional products that apply best industry practices and use components rated high enough for a more than sufficient margin of error. I'm sure a person could fry a Hi-Watt if they did all the "right" things. Everything has its Achilles heel.
that mastortion is making me reaaaaaaallllly curious!!!
and it sounds really fine as well!
I once put my Colorsound Overdriver in the FX loop of my old practise amp
It worked for a while; live it started to turn the volume up on the Overdriver. Then the amp started smoking (and sounding really good)
Now it is a passive monitor :)
I just bought a nice solid state bass amp from 1979 and i would hate to kill it, however i would like to have maybe a boost and some other effects.
So is overloading imput something i should worry about unless i do some realy silly things?
Both the amp and cabs have some fuses i will replace with some weaker ones (thanks for the tip) but will this make it foolproof?
Anything special to take into concideration with old solid state amps?
I'm asking cause i don't wanna know from experience what not to do with an amp.
Boost is one thing. Distortion at the transformer and speaker level quite another. Unless you are certain the speakers are rated well above what the amp could ever possibly hope to deliver, they will almost always be your weakest link as far as abuse-related malfunctions go (obviously you can always bugger up a pot or switch, but that was not the nature of your question).
For bass, try to keep a few things in mind:
- A little bit of limiting goes a long way. Note that I say limiting and not compression. Limiting prevents sudden peaks from exceeding some preset value, while leaving everything below that ceiling unaffected and at its original level. Compression attempts to maintain a constant level by bpopsting weaker portions of the signal. At low volumes, compression is a wonderful thing, but at higher volumes it is everything an amplifier and speaker were designed to avoid.
- Speaker voice coils are generally suspended in the gap without touching anything. At higher amplitudes, their movement is not purely piston-like and there will often be some friction as the coil touches the sides of the magnet structure. A little bit of sluggish rubbing is tolerable and does not result in significant heat build-up. Lots and lots of fast rubbing (and you should interpret this to mean tons of treble and harmonics from, oh I dunno, distortion pedals) at high amplitudes results in heat build-up which the speaker coil can not dump as fast as it occurs. At higher heat the voice coil is simply a fuse, waiting to burn. So, if you are going to have a distorted sound, either keep the volume restrained, or if it needs to be louder make a point of taming the treble.
I had the input stage of a small SS practice amp go smokey while I was feeding it a boosted fuzz signal. But I doubt it died from overloading, because the opamp input stage was running on +/-15v--it probably didn't even overload.
Cool, thanks alot for the quick and ediucating replies guys :icon_eek:.
Seems to be a subject that atracts quite alot of myths.
I got quite supprised to find that my cabs had fuses acctualy, as i understaind it they will only blow if i pass enough current through them and are not helping against the distortion demage problem ???.
The fuses in the amp will almost always save the amp if i would do something silly or stupid (right?) :icon_rolleyes:
Can i destroy an amp with a FX pedal?
depends on the size, weight, and force by which you will be throwing at the amplifier...or shooting....
There's a story in "Analog Man's Guide to Vintage Effects" where a guy who helped design the Moog Stage Phaser mentions making a custom rack version of it for Keith Emerson, and trying it out with a live PA. They had it operating in inverse mode (peaks instead of notches), with the sweep frequency under CV control. When the lowest peak swept down into subsonic frequencies, it blew up a 400 watt amp.
Likewise, I can imagine that a bass through an auto-wah pedal with a high resonance setting and low cutoff might be capable of blowing an amp. Think "Bill Laswell through a DOD FX-25" taken a little too far...
Quote from: Albot on August 03, 2007, 04:01:52 PM
Cool, thanks alot for the quick and ediucating replies guys :icon_eek:.
Seems to be a subject that atracts quite alot of myths.
I got quite supprised to find that my cabs had fuses acctualy, as i understaind it they will only blow if i pass enough current through them and are not helping against the distortion demage problem ???.
The fuses in the amp will almost always save the amp if i would do something silly or stupid (right?) :icon_rolleyes:
I'm not sure the subject attracts myths as much as it generates them, since not as many people spend the time to learn about how speakers work when they need to devote their time towards mastering software or complex controls. As a result, stuff that makes you smack your forehead and go "Well, of COURSE!" after you grasp it, tends to bypass a great many users.
That's good that the cabs have fuses. I hope that is a sign that other precautions have been taken as well, rather than a sign they threw in a fuse because they knew they were taking too many risks elsewhere! I'm leaning towards the former rather than the latter, so you can exhale.
Will the fuses "save" the the amp? If they are rated appropriately, and are fast blow, probably. I can't imagine, however, that I am the first and last guy in history to blow a 2A fuse, find he doesn't have a spare in the parts bin, replace it with a 5A slow-blow under the assumption that he won't be cranking the amp past the critical point, and then forgets that he put a 5A slow-blow where a 2A fast-blow was supposed to be. So, make sure the fuses are rated appropriately....for
real....not just on the chassis label.
And, I will still put in a vote for a touch of limiting so that you never have to rely on the fuses alone. :icon_wink:
i'm going to go against the flow and say the chances of you frying ANYTHING with ANY stompbox that is properly wired are slim to none, short of mark's wise warnings about blowing speakers. there is a finite voltage you are going to see on the output of a pedal, and no amp circuit i've ever seen would come close to frying at it's top end. speakers, on the other hand, you can blow quite easily.
Yes, but once the speakers are blown the amp is left running with no load, which can cause damage.
I did some repairwork for a Crate solid-state amp that a friend broke. He took a drum machine (figure, 1-2V peak-to-peak max output), ran it straight into the amp, and dimed all the distortion / drive circuits. After a few minutes of blissful industrial rock action, the amp let out a wisp of smoke, and lost a good bit of power. When he tried using it again a few days later (under less-stressful circumstances), it refused to play a single note.
I opened it up and discovered that a single resister had blown. Crate had selected 1/4W resisters, and I think they figured that no-one was going to run such a strong signal into their amp. I replaced the resister, and everything seemed just fine. I kept the amp for some time, then lent it out to a neighbor so that he could practice his punk rock musings at home. It came back to me a few days later, again dead. I didn't ask what he was doing, but I opened it up, and if I remember correctly, the same resister had gone. I'm going to guess that what the first friend did caused more than a single resister failure-- perhaps weakened some other part of the circuit. As I recall, I fixed it again, and sold it off for some pittance, with due warning to the buyer.
Another story, not quite so relevant. I was in a noise performance band, and was eager to try out my MOTM synth modules at stage-volumes, through a recently acquired QSC power amp (~280W total? 140W/channel) and single PA speaker. The QSC output wasn't bridged, so in theory the PA should have only seem 140W at peak. The MOTM puts out something like 10V peak-to-peak. I had the QSC turned up to something like... 4? Blew the PA speaker in 5 seconds. I took the PA cab apart when I got home, and by manually excersizing the cone, found that the voice coil was toast-- there was a distinct scraping sound as it flexed. I think the markings on the speaker cone was rated around 100W? I replaced the speaker with something rated around 200W, and had no further problems.
So, uh... watch that gain-staging, kids!
Quote from: object88 on August 03, 2007, 09:00:32 PM
I did some repairwork for a Crate solid-state amp that a friend broke. He took a drum machine (figure, 1-2V peak-to-peak max output), ran it straight into the amp, and dimed all the distortion / drive circuits. After a few minutes of blissful industrial rock action, the amp let out a wisp of smoke, and lost a good bit of power. When he tried using it again a few days later (under less-stressful circumstances), it refused to play a single note.
I opened it up and discovered that a single resister had blown. Crate had selected 1/4W resisters, and I think they figured that no-one was going to run such a strong signal into their amp. I replaced the resister, and everything seemed just fine. I kept the amp for some time, then lent it out to a neighbor so that he could practice his punk rock musings at home. It came back to me a few days later, again dead. I didn't ask what he was doing, but I opened it up, and if I remember correctly, the same resister had gone. I'm going to guess that what the first friend did caused more than a single resister failure-- perhaps weakened some other part of the circuit. As I recall, I fixed it again, and sold it off for some pittance, with due warning to the buyer.
Was that from the input signal being too large, or the amp working too hard? I'd put my money on the latter. Sure, running something like 30V peak-to-peak isn't going to be good for an amp, but most pedals have nowhere near the output power to fry your amp. I wouldn't be too concerned if I was you.
Quote from: Barcode80 on August 03, 2007, 07:12:11 PM
i'm going to go against the flow and say the chances of you frying ANYTHING with ANY stompbox that is properly wired are slim to none, short of mark's wise warnings about blowing speakers. there is a finite voltage you are going to see on the output of a pedal, and no amp circuit i've ever seen would come close to frying at it's top end. speakers, on the other hand, you can blow quite easily.
interesting topic that i dug up searching for a review of analog man's book. not too old i hope.
i've been recently thinking of making an opamp boost of about 20 gain that uses the geofex charge pump idea. having read above i started second guessing, especially since i make a lot of use of 'budget' practice amps. i fried the speakers in a fender fm212r by running the amp with a 250v source instead of 240v.... TOUCHY huh? it came back from fender with the new speakers soldered in instead of having the spade connections :P perhaps they assumed i plugged them into something else.
after reading Barcode's comment I thought "yeah, hold on, we're just talking 9v stompboxes here... a coupling capacitor at the end and hopefully one on the amp's input" is 17v getting to be a bit too much to assume safety though? if a gave a pedal to a bass player with 20x clean gain potential, would that start leading to problems and blame in my direction?
i once brought a circuit to show a friend which had not been housed yet. as in, it was a board with everything offboard on short wires. he refused to let me plug it in because "everything's all dangling everywhere". i gave it a moments thought and in the same moment told him it was very safe.
If a battery-powered pedal destroys an amp, then the amp was junk and DESERVED to die! I've used an abused guitar gear for almost 20 years making all kinds of horrible noise and I've never blown up anything, except the occasional junk speaker. The only thing that ever blows up for me is these junk PAs that no one seems to be able to set up properly... :icon_rolleyes:
Quote from: Toney on August 03, 2007, 11:39:43 AM
When I was a kid I destroyed the phono in on my stereo buy feeding it an active bass.
We were kids! We wanted to jam but no amps.
I did something like that too- plugged my bass into the rec input on my tape deck (hey it was 1991) and then ran i through my stereo. I was sitting on the edge of my bed playing, not even too loud if i remember right, and something caught my attention out of the corner of my eye- the speaker behind me was on fire! This was a 12" eminence rated at 120w coming from a 100w head unit. The cone itself had caught fire somehow. Never figured out how that happened, the speaker must have gotten really really hot.
I would say as long as the volume coming out of the amp is the same with the effect on and bypassed you should be ok, other things being equal like no DC or other strange ultrasonic frequencies.