• The Gear Page Apparel & Merch Shop is Open!

    Based on member demand, The Gear Page is pleased to announce that our Apparel Merch Shop is now open. The shop’s link is in the blue Navigation bar (on the right side), “Shop,” with t-shirts, hats, neck buffs, and stickers to start. Here’s the direct link: www.thegearpageshop.com

    You’ll find exclusive high-quality apparel and merchandise; all items are ethical, sustainably produced, and we will be continuously sourcing and adding new choices. 

    We can ship internationally. All shipping is at cost.


Can overdrive pedal damage amplifier circuitry?

Grun

Silver Supporting Member
Messages
2,094
Can pedals such as overdrives or multi-effects units damage amplifier components? If so, what would possible syptoms be?
 

WaltC

Member
Messages
2,129
The short answer is... no.

While it might be theoretically possible for some pedal or component to cause some sort of damage to some amp either in the input or effects loop, it is extremely unlikely.
 

MstrBones

Member
Messages
248
An overdrive will shorten tube life as your upping the signal. Hard to say how much as people tend to use them intermittently and at different gains.
 

donnyjaguar

Member
Messages
4,199
I have to agree with WaltC. Generally, at least for me, the processed sound is equal to or only slightly greater than the bypass level. If the first voltage amp is a 12AX7, and it almost always is, you can punch in a ball-busting signal and still not saturate it. Generally the volume control is the next stage and this will be adjusted down anyway.
 

SatelliteAmps

Member
Messages
6,182
An overdrive will shorten tube life as your upping the signal. Hard to say how much as people tend to use them intermittently and at different gains.
Never seen this happen. Tubes are meant to take voltage (signal) increases with no problems. If you have an amplifier with 4 gain stages, each one of those stages is increasing the voltage going to the next stage. An overdrive that would increase the voltage enough to cause damage would be something that I've never seen exist.

Increases in voltage do not shorten tube life. If they did, people would be changing their last stage preamp tubes more often than anything else, and there would be a routine failure of that specific tube in every amplifier.

There is no danger from using commonly sold effect units causing any kind of damage to an amplifier.
 

5er Driver

Member
Messages
181
Marshall Major - Yes, "Smoke on the Water effect". Ritchie found this out first hand. According to Dawk Stillwell, Ritchie's amp & guitar tech at the time (Sorry, he writes only in caps):

">>>> ''WHAT IN THE HELL'S'' IS: ''THE SMOKE ON THE WATER EFFECT'' ?

FIRST SOME OF THE HISTORY OF THIS CAME FROM ''MARSHALL'S OWN ''KEN BRAN'' AND THE REST IS FROM MY YEARS OF EXPERIENCE OF WORKING ON THEM...

IT ALL STARTED WHEN ''DEEP PURPLE'' WENT FROM PLAYING CLUBS TO 20,000 SEATERS...

MANY PROTOTYPES OF A 200 WATT AMP WERE BUILT BY ''MARSHALL'',,, THEY ALL FAILED... (SOME PRTOTYPES HAD (6) EL-34'S IN WHICH THE TUBES GOT SO HOT THE GLASS MELTED)...

SOO, THEY HAD ''GEC'' DESIGN ONE FOR THEM... IT'S THE COMPANY THAT MADE THE FAMOUS ''GOLD LIONS'' (KT-88'S ) TUBES...

TO GET THE 200 WATT RMS RATING ''GEC'' HAD TO BOOST THE B+ TO (650) VOLTS DC... THE MAXIMUM DESIGNED RATING FOR A (KT-88) IS (450) VOLTS PLATE VOLTAGE...

THEN TO TOP THAT OFF THEY USED AN ULTRA LINEAR DESIGNED OUTPUT TRANSFORMER... IT'S BASICALLY DESIGNED LIKE A HI-FI AMP...

THE MAJOR HAS A VERY CLEAN SOUND AND LOW GAIN,,, WHEN COMPARED TO THE REST OF THE ''MARSHALL'' LINE...

THERE'S NO OTHER AMP MODEL THAT SOUNDS LIKE A ''MAJOR''...

THAT'S WHY ''BLACKMORE'S'' SOUND ON ''MADE IN JAPAN'' (SOUNDS SO GOOD)... (OR YOU COULD SAY YOU CAN HEAR EVERY MISTAKE CLEARLY)...

THOSE PEOPLE AT ''MARSHALL'' BACK IN THE DAY DIDN'T KNOW WHAT ''ROCK AND ROLLERS'' WERE GOING TO DO TO THAT AMP...

WHEN A BOOSTER OR SOME KIND OF OTHER PEDAL WAS USED TO MAKE SOME DISTORTION THE (650) VOLTS OF B+ WOULD JUMP TO (1800) VOLTS THAT'S CALLED OVERSHOOT...

(THE ULTRA LINEAR OPTX CIRCUITS ARE NOT DESIGNED TO HANDLE COMPLEX OVERDRIVE SOUNDS AT HIGH VOLUME LEVELS)...

ONCE THE SIGNAL STARTED TO BUILD UP TO AN SQUARE WAVE THE OPTX STARTED SWITCHING AND ((( BLAM )))...

THE OPTX IS WORKING SORT OF LIKE A ''FLY-BACK'' TRANSFORMER IN A TV SET,,, THAT WHAT'S PRODUCING THAT HIGH ''IPV'' VOLTAGE...

IT'S LIKE TURNING OFF A WATER FAUCE AND HEARING THAT ''BANG''...

(IF IT WASN'T FOR THE HIGH QUALITY OF THOSE ''ENGLISH'' (KT-88'S) THAT AMP WOULD HAVE BEEN DEAD IN THE WATER...

THEN THE (B+) @ (1800) VOLTS WOULD ''ARC'' OVER TO THE CLOSEST GROUND,,, USUALLY BETWEEN PINS (2) AND (3) ON THE OUTPUT TUBES...

THAT CAUSES A LOT OF SMOKE,,, BURNING OF THE TUBE SOCKET AND A REAL BAD SMELL...

''THUS LEAVING A ''BIG'' BLACK ULGY CARBON MARK INSIDE THE CHASSIS WHERE IT ARCED''...

''THIS WOULD HAPPEN SO FAST THAT IT DIDN'T HAVE TIME TO BLOW THE FUSE...

>>>''BLAM''..................... ''SOMETIMES THE FUSE HOLDER ITSELF WOULD EXPLODE''...

>>>>>>''THE SMOKE ON THE WATER EFFECT''...<<<<<<<

PT. (2).....

BY THE TIME THAT PRODUCTION WAS STARTED AND THE COST OF WARRANTY REPAIRS ON THESE AMPS ''MARSHALL'' TOOK SOME STEPS LIKE:

COVERING THE PRIMARY LEADS OF THE OPTX WITH EXTRA INSULATION,,, AND CHANGING THE TUBE SOCKETS TO CERAMIC...

THEN THE ''IPV'' WOULD ''ARC'' OVER IN OTHER PLACES LIKE,,, ON TOP OF THE TUBE SOCKET OR INSIDE THE TUBE BASE...

THE WORST BEING INSIDE THE OUTPUT TRANSFORMER ITSELF...
THE TRANSFORMER COULD TEST GOOD BUT,,, THEN ONLY TO ARC OVER AGAIN WHEN THE FIRST HARD CORD WAS PLAYED...

MOST OF ALL THE ORIGINAL ''DAGNALL OUTPUT TX'S ARE DAMAGED IN THIS
MANOR... THE AMP WILL,,, PLAY OK,,, UNTIL IT GETS A LOUD SIGNAL,,, LIKE A
HEAVY CORD AND THEN >>> (BLAM) <<<...

>>>>''SOO,,, IT'S SMOKE ON THE WATER TIME AGAIN''<<<<<

BECAUSE,,, THERE NO SIGNS OF AN ''ARC'' OVER IN THE CHASSIS,,, YOU'RE NOT REALIZING THAT THE ARC OVER WAS INSIDE THE (OPTX) ITSELF...

NOW THE WARRANTY REPLACEMENT GOT VERY COSTLY FOR ''MARSHALL''... NEW OPTX AND NEW (KT-88'S) AS WELL...

SOO,,, THAT WAS THE MAIN REASON FOR THIS AMP TO BE DISCONTINUED BY (1974)...

THERE WERE MANY MORE REASONS FOR THIS DECISION OF COURSE...

LACK OF SALES AND THEIR HIGH PRICE ALSO PLAYED A PART...

''KEN'' TOLD ME,,, ONCE THAT ALL THE PARTS THAT COULD BE INSTALLED BY ''THE GIRLS'',,, ONLY THEN WOULD THE HEAVY TRANSFORMER'S GO ON THE CHASSIS...

THIS MADE THE AMPS TO HEAVY FOR THE GIRLS TO PICK UP AND MOVE AROUND ON THEIR BENCHES...

>>>> A ''KEN BRAN'' QUOTE: WE HERE AT ''MARSHALL'' WERE LOADED WITH BACK ORDERS & BACK ORDERS... (KEN EXPLAINS)...

THE GIRLS DOING ALL THE ASSEMBLY WORK COULD BE MAKING (3) ''50'' WATTERS AND (2) ''100'' WATTERS IN THE SAME TIME IT TOOK TO BUILD
A (200 WATT MARSHALL MAJOR)...

THE LAST (50) ''MARSHALL'' MAJOR'S WERE MADE IN 1974...

AN TOTAL NUMBER OF (1,200) OF ALL THE MODELS WERE MFG...

THAT ACCORDING TO ''MITCH COLBY'' AT ''KORG'' USA...

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

PT. (3)

PS: YEAH,,, I'VE ALREADY TRIED THAT OLD HAM RADIO TRICK OF CLAMPING DIODES ON THE OUTPUT TRANSFORMER...

IN FACT IT'S ''OLD HAT'' AND EVERYBODY KNOWS ABOUT IT...

I DID THAT OVER THIRTY YEARS AGO...

THAT WORKED BUT,,, IT STILL BLEW THE FUSE RIGHT IN THE MIDDLE OF YOU'RE SOLO... ''AN CATCH 22''...

>>>> ''NEVER'',,, AND I MEAN ''NEVER'' RUN THESE AMPS WITH TWO OF THE OUTPUT TUBES PULLED OUT,,, >>>> (((( IT WILL,,, BLOW IT ))))...

I'VE GOT AN '69 PLEXI OUT AND WILL,,, BE USING IT AS TEST BED FOR THE NEW MERCURY MAG OUTPUT TRANSFROMER...

I ALSO WILL,,, BE TESTING THE NEW KT-90'S TUBES FROM NEW SENSOR...

YOURS,,, JOHN''DAWK''STILLWELL... "
 
Last edited:

SatelliteAmps

Member
Messages
6,182
That is an awesome story. It's not true, but it is awesome.

A couple of technical issue's that make this not work out. First off, it's not the note played that determines the B+ voltage, it is the power transformer. When a note is played (even with a booster, or even an extra tube preamp) the B+ will change some, but it doesn't triple.

The filtering on those amps (if I am remembering correctly, I know I'm pretty close), were 450v caps. Even running a pair in series will only get you 900v of filtering, which would explode if they were hit with 1800v.

The KT88 was introduced in the mid 1950s, way before the Major or even Marshall Amplifiers existed. According to the Genelex Data sheet, the design max is 800v. (The really old GEC one claims a max of 600v, but then goes on to show examples with them getting 650v.)
 

donnyjaguar

Member
Messages
4,199
No, the B+ doesn't change, nominally. Its the differential betwixt the plate voltage and the B+. This is the autotransformer effect so you get a situation where the plate voltage is much higher than the B+ and the arcing occurs between here and the chassis ground.

I don't want to sound like Bill Gates here, but good gawd, who the devil needs 200Watt guitar amplifiers nowadays?? :)
 

hasserl

Member
Messages
4,709
Guitar amps aren't about needs, they're about WANTS. ;)

You guy's are right, a boost pedal won't cause an increase in B+ voltage. I think what the guy is talking about is flyback voltage, which in the case of a Marshall Major I'll bet can probably go a lot higher than 1800 volts, depending on the circumstances. I'm really not experienced with those amps, so I'll not venture a guess about instabilities of the design and what would cause the high flyback. But in context of the OP, I doubt the guy has a Marshall Major in mind when he posted. I think Walt's answer is still valid.
 

tommytomcat

Member
Messages
355
Not if you're using the pedal within reason.. If you crank the output really high on the pedal and amp, you're going to stress the amp in several places. I fried a 6v6 and the screen grid resistors on a deluxe reverb once by cranking everything up really loud and playing power chords. I wanted to see how loud I could get the amp to go.
 

MstrBones

Member
Messages
248
>Tubes are meant to take voltage (signal) increases with no problems.

I don't disagree and I never said it damaged the tube.

I had thought that higher signal gain does force more electrons to be boiled off the cathode, but in reconsideration, it simply allows more electrons to pass thru the grid to the plate.
 

audiozone

Member
Messages
280
i made a preamp tube in a fender tremolux explode once with a fully cranked big muff pedal. it blew the pointy glass top right off. the amp worked fine with a new tube.
 

hasserl

Member
Messages
4,709
i made a preamp tube in a fender tremolux explode once with a fully cranked big muff pedal. it blew the pointy glass top right off. the amp worked fine with a new tube.
C'mon, think about it, how would it do that? Impossible.
 




Trending Topics

Top