You are correct. I have a 10X probe that wasn't made by Tek so it doesn't automatically show the 10X on the scale. My brain works faster than my arthritic fingers can type, and outran me while in a hurry.
My wife had a low tire and my daughter had a dead battery this morning. Both were late for work. I had to deal with both in -8 degree weather. The phone rang with my daughter screaming "my car won't start" as I was typing this. Thus two non related thoughts wound up together.
I captured this initial transient on the scope. I have seen bigger ones, but I just happened to catch this one on the scope. The peak is about 1.4 volts P-P, and the only info I saved was "single note Guild."
These pictures were being made as I was testing alternative OPT's for the HBAC, an exercise in ultra low buck guitar amps. Cheap power (mains) toroids DON'T LIKE this transient when used as the OPT. Saturation causes a surge of current in the output tubes, and some resultant distortion that is not present with a real OPT. I think I had to use a 50 or 100VA toroid to kill the saturation.
In a totally different experiment I set the scope in storage mode with infinite persistence, free running and just thrashed on the guitar playing random notes on all 6 strings and managed to find a bunch of excursions around 3V P-P. I don't recall the guitar or pickup combination used. These experiments were in response to someone's question in the HBAC thread about the maximum output from a guitar. There were other responses too, and maybe some other measurements, but that is a long thread (2100 posts) full of arguments about stuff that really doesn't matter.
I started experimenting with the GraphTech piezo pickups more recently so that I can get a separate output for each string. I have some rather weird ideas for a six string (no keys) and the usual buttons and knobs MIDI controller. Vacuum tubes are not significantly bothered by the transients.
A humbucker typically puts out a bit less voltage than a hot single coil. The coils in a humbucker are wired out of phase, but only one coil has a strong magnet system. This way a stray 60 Hz magnetic field should hit both coils, and cancel (buck) because they are wired out of phase. The guitar string only acts on one coil since only one coil has magnets. In practice both of these are only partially true since the stray 60 Hz rarely hits both coils equally, and some residual magnetism gets into the "dead" coil. The "deadness" of that coil decreases with frequency, which is one reason a single coil will produce more high frequency than a humbucker.
Somebody used to make a "humbucker" with 4 wires. You could put a switch to reverse, or disconnect one coil allowing all sorts of tonal insanity. I haven't seen one in years, but I haven't really looked either.
I wonder if the ~500 pF capacitance of a typical 15-foot guitar cable would make a substantial difference?
I too have never seen more than about 1 - 1.5 volts peaks (measured years ago with a peak-hold precision rectifier circuit I built, because I didn't have a 'scope at the time.) It's been a lot of years, but I'm sure I was using a length of guitar cable between guitar and electronics - though I don't remember exactly how long it was.
There is a wide "dynamic range" in guitar players, too, which tends to be in inverse proportion to their playing ability.
Pete Townshend is a famous example. He was unable to play lead guitar the way his contemporaries like Jeff Beck or Eric Clapton did, so he opted for swagger and visual showmanship over musical ability: wild windmilling arm swings that were slow, clumsy, and savaged the guitar (and probably put out several volts peak to peak), but impressed drunken or drugged-out audience members.
At the other extreme, extremely fast and precise lead guitar players at the top of their profession, like Glen Campbell, Tommy Tedesco, Yngwie Malmsteen, and Steve Vai, tend to use tiny, hummingbird-fast picking movements, played with a light touch. I would not be surprised if peak outputs from their guitars were ten times smaller than Townshend's.
-Gnobuddy
Did he windmill also?
I've got a G&L telecaster single coils. I seem to recall seeing about a 1V peak signal.
I pulled the cab out of the wood shop where it's been drying. It's got two coats of clear varnish now.
The front panel was spray-painted flat black before glueing in, so it doesn't show through the grille. (Edges were not painted, so the glue can do its thing.)
The odd black shape you see through one speaker opening is one of the two black plastic port tubes.
The back panel you see in this photo is inset about 2" from the rear edge of the cab. It isn't glued in place yet, but will be soon, once I mount the speakers and attach the handle.
There is about a 2" space behind the back panel, where the electronics will live.
-Gnobuddy
The front panel was spray-painted flat black before glueing in, so it doesn't show through the grille. (Edges were not painted, so the glue can do its thing.)
The odd black shape you see through one speaker opening is one of the two black plastic port tubes.
The back panel you see in this photo is inset about 2" from the rear edge of the cab. It isn't glued in place yet, but will be soon, once I mount the speakers and attach the handle.
There is about a 2" space behind the back panel, where the electronics will live.
-Gnobuddy
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We just had an ice-storm here that covered a couple of cities near us. We drove out to one of them yesterday to spend New Years Eve with friends, and got a show of beauty that I've never seen before.
Every exposed blade of grass, twig, leaf, branch, fence wire, was covered in a layer of clear ice, lit up by the sun low in the west.
We went out and took a few photos today. Much of the ice has melted, but there is still an impressive amount left.
-Gnobuddy
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And here I was expecting to get in trouble for mentioning studio cats and shredders instead of the usual suspects (loud, inebriated, cocaine-snorting rock guitarists.)
-Gnobuddy
I think Prince usually had two or three women draped over him. That might have hindered his windmilling ability.
So we have people who've seen ten volts, people who've seen one volt, and people who've seen one-tenth or one-twentieth of a volt (Merlin Blencowe's preamp book, for humbuckers and single-coils respectively).
Meantime, Fender seems to design their guitar amps for one-fiftieth of a volt (20 mV) input sensitivity. Apparently they expect a real-world guitar signal level in that range.
So we have ended up with a range of "maximum peak guitar signal voltage" measurements that span a rather extraordinarily large range of 54 dB.
This is beginning to drive me slightly nuts!
-Gnobuddy
"Sensitivity" is not "input overload".
We have knobs for that.
As you say, some players prefer to work with 20mV hummingbird pecks, and may wish to have them delivered near the maximum power of the amp. Other players tilt with windmills, and either have their rig turned-down for 200mV sensitivity or accept(embrace) input overload.
The very oldest "electric amplifiers" had no knobs, because any amplification was a novelty, Hawaiian guitar was not supposed to be loud, and the first amps had little gain. But gain is cheap and became desirable in other styles (especially to get a gig behind a horn-band). Higher-gain (50mV) amps arrived, and add-on volume controls were early options. Today a full rig has a knob on the guitar, a knob after the first amp stage, and a knob before the power stage. Even if all Linear that is 60dB of gain-range possible (though we don't need more than 40dB).
Design so full-up 20mV will make full power; and at some turn-down point it will accept over 200mV without clipping in the first stage. "Over 200mV" is player specific: Some won't make that much, others eat spinach or stack booster pedals and deliver over 1V. An amp input which will not take a large signal *may* be accused of "not taking pedals well"; several such otherwise fine amps need input mods to take the huge level off some players' pedalboards. Other players with mild picks and no boost may never run into this "problem".
Originally the amps were being used to amplify the whole band or at least a few different inputs. Microphone inputs along with guitars, not the high output pickups we have now. Also you might get some loading of one input to the other if using both inputs on one channel. Speaking of, you might get a lower peak signal going through a cord to a 1M resistor input rather than a 10M scope input.
And here I was expecting to get in trouble for mentioning studio cats and shredders instead of the usual suspects (loud, inebriated, cocaine-snorting rock guitarists.)
-Gnobuddy
Eric Clapton was asked about how it felt to be the world's best guitarist. His response: "I don't know. Ask Prince"
So we have ended up with a range of "maximum peak guitar signal voltage" measurements that span a rather extraordinarily large range of 54 dB.
This is beginning to drive me slightly nuts!
And just when you thought you were beginning to see the light!
I've been in the cult-of-the-clip for a long time now: how an amp deals with overload conditions is, for me, critical. This is true even in hifi where it's supposedly 1V RMS or bust, but best estimates suggest typical 85db speakers will need 500+W to avoid clipping on (properly recorded) transients at "realistic" levels.
As a guitarist, 54db sounds about right: I'd say I get 25db or 30db just through picking technique, before we start fiddling with strings, plectrums and pickups. And I'm a crap guitarist.
Nice discussion!
Something about humbucking pickups... The two coils are indeed wired out of phase but - the magnets are also opposite polarity. One coil has its north pole facing up, and the other coil has its south pole facing up. The net result is that, while the induced signal from external magnetic is cancelled, the induced signal from string vibration is additive.
Everything else being equal, the signal from a humbucker will be stronger. As evidenced by the lower relative volume when using coil tap switches.
I just built a guitar with some pretty hot pickups. At some point I'll do another capture and compare with my earlier measurements. I still have the piezo test rig with the GraphTech pickups so can easily re-measure that one as well.
My go-to in those situations would probably be Enter Sandman
Didn't we have this discussion like 5 years ago? Deja vu...
Something about humbucking pickups... The two coils are indeed wired out of phase but - the magnets are also opposite polarity. One coil has its north pole facing up, and the other coil has its south pole facing up. The net result is that, while the induced signal from external magnetic is cancelled, the induced signal from string vibration is additive.
Everything else being equal, the signal from a humbucker will be stronger. As evidenced by the lower relative volume when using coil tap switches.
I just built a guitar with some pretty hot pickups. At some point I'll do another capture and compare with my earlier measurements. I still have the piezo test rig with the GraphTech pickups so can easily re-measure that one as well.
My go-to in those situations would probably be Enter Sandman
Didn't we have this discussion like 5 years ago? Deja vu...
Probably. Metallica were just kids when I blasted Miss Disco with Smoke.....it had to be about 1975.
That makes more sense. Maybe the old DiMarzio's that I've got have dead magnets since a screwdriver barely sticks to the rear pole pieces. I have had them for almost 40 years and they are still in their plastic boxes. I traded some 8 bit computer stuff to a luthier for some of his unused leftovers back in the late 70's.
The Machine Head album is the one that really motivated me to get an electric guitar.
Smoke on the water played on acoustic just didn't have the same impact
Blackmore's tone and technique are near perfection on that album. Rumor has it he used an AC30 rather than the usual Marshalls.
For us connoisseurs of killer "low gain" overdriven tone, this has got to be one of the benchmarks.
For an example of the "gling" I keep yapping about, and please don't laugh too hard, the Monkees "Last train to Clarksville". Probably was played by the Wrecking Crew. Last train to Glingsville.
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