I always thought guitar amps were first about tone and about playability (that is to say, its possible to play the amp like its part of your instrument). Noise is usually secondary. If using guitar pedals, a noise-gate pedal can help. Also some guitar amp noise such as intermittent frying noise can be caused by AC line noise. An especially good power conditioner can help a lot with that. A mediocre power conditioner might not help at all though.
Also, IME most guitar amps are voiced so that a guitar will sound best with the volume and tone pots on the guitar set to about 5 (at least as a starting point). Then adjust the amp to get a good tone and so that the gain structure is such that plucking one string moderately is pretty clean, but a double stop starts to break up a little. That's probably roughly around where the amp is most playable using guitar playing technique.
IOW, noise is not usually the most important thing, unless maybe the amp is broken.
Would agree that the amp should be chosen for the style of music, and if playing with a band, the sound of the amp should sit naturally in the mix (not too fat nor too thin, etc.).
Also, IME most guitar amps are voiced so that a guitar will sound best with the volume and tone pots on the guitar set to about 5 (at least as a starting point). Then adjust the amp to get a good tone and so that the gain structure is such that plucking one string moderately is pretty clean, but a double stop starts to break up a little. That's probably roughly around where the amp is most playable using guitar playing technique.
IOW, noise is not usually the most important thing, unless maybe the amp is broken.
Would agree that the amp should be chosen for the style of music, and if playing with a band, the sound of the amp should sit naturally in the mix (not too fat nor too thin, etc.).
At what frequency? 8 kohm to 15 kohm at 1 kHz would correspond to about 1.25 H to 2.4 H, same order of magnitude as what I remember as the values for non-humbucking pick-ups from PRR's post that I can't find anymore. Mind you, it's about ten times as much at 10 kHz.
The last time I went to a lute concert, the lute had no volume control, and that didn't seem to bother the guy who was playing it. Why is it essential for an electric guitar?
I always use the word noise in the technical sense, a random or pseudorandom signal that usually sounds like hiss if it happens to be audible. It can be masked by hum if the hum is loud enough
How do you come to the hypothesis that it is caused by the tubes? Unless the input tube is gassy, has grid emission or is biased at a far too high grid-to-cathode voltage, its noise should be negligible compared to the thermal noise of the guitar volume control when that is set halfway.
Carbon composition resistors can certainly become the dominant noise sources when they are used in the input stage and have substantial bias voltages across them.
In some other guitar amplifier thread, someone was fixing a 1970's guitar amplifier with a bipolar transistor input stage biased at a much too high current. Its base shot noise dominated everything. Replacing that transistor with a JFET and some carbon composition resistors with metal film resistors substantially reduced the noise.
Sorry to the OP for going so far off track now, but is he even still participating?
I think for the same reasons some bassists use solid state amps, but guitarists generally prefer tube amps - the tonal spectrum being produced. Even with bass players, especially those trying for those more vintage tones from a big tube bass amp.
Regarding onboard electronics - I do agree with your assessment, but mostly these days, not 40 years ago when I loaded up my guitars with DIY boosters, buffers and compressors. At that time, the Craig Anderton series in Guitar Player and his books were very popular, and there were a lot of guitars fitted with essentially what guitar players now get with pedals. There are so MANY pedals out there for guitar, it seems to me there is a lot of interest in tonal modification, even though many still prefer tube amps.
It strikes me as funny that all of the emulators being developed and perfected are meant to replace tube amps and the sounds from those amps, just as impulse response functions are used to emulate real speaker cabs.
No idea. Inductance is not really given by guitar pickup manufacturers. Magnet type, bobbin type, potting/no potting, wire diameter, etc., and coil resistance, which is variable. I think a lot of single coil pickups actually are wound to about 5.5-7k. Guitar players are generally not engineers, so they spend a lot of time and money chasing the tone they are looking for.
I'm not talking about amplified acoustic guitars, but electric guitars that use the amplifier as basically 1/2 of their instrument. Have you never listened to rock music? You could try Youtube or some other venue and watch/listen to some electric guitar music. There is a lot of manipulation of all aspects that create/affect the sounds and tone. I can make some suggestions for you if you wish.
OK. I'm not a trained electronics engineer, and may use incorrect terminology. What I said however, is accurate.
OK, guess I'm being imprecise again. Please refer to my initial suggestion to the OP that he select a different same type tube or perhaps a lower-gain tube. The entire circuit is of course responsible for noise (hiss, hum, or any other unwanted sounds), but high-gain amplifiers and high-gain tubes like 12AX7 tend to produce plenty of hiss. Also, guitar amps tend to run higher plate voltages (and screen/plate for output tubes) than recommended by the manufacturer or the datasheets, which can increase hiss, as well as change the tone and response of the amp.
Guitar players live with it. Primarily by using the volume control during song breaks or quieter passages.
Yes, and some newly built amps based on old designs faithfully use CC, and there are a number of effects from using them. Please understand - guitar players don't select amps using the same criteria that audiophiles select amps and preamps.
Last edited:
Very much so. A prestigious radio broadcasting station probably had a few research-grade engineers on staff. Electric guitar, on the other hand, was considered an idiotic fad by the majority of people, and all the early work in the field was done by tinkerers. Most of those tinkerers were neither scientists nor engineers. Many early attempts stopped at the level of unscrewing a telephone mouthpiece and mounting it to the body of an acoustic guitar.
Keep in mind that noise floor is pretty far down the list of desirable qualities in the context of a guitar amplifier. The actual timbre of the amplifier - which is a combination of its steady-state frequency response, and various nonlinearities in its transfer function - is far, far more important.
When you say "poorly designed", that has to be qualified by context. I'm not a gear snob, and don't own collections of expensive musical gear; but one of my guitar amplifiers is a reissue '65 Fender Princeton Reverb, an amplifier design that has been held in high esteem by electric guitar players for the best part of sixty years now.
If you ask a knowledgeable electric guitarist if a '65 Princeton Reverb is poorly designed, you'll get an emphatic "No!"
However, if you ask a JPL engineer who works on a receiving amplifier cooled to nearly liquid helium temperatures so that it can pick up incredibly weak satellite transmissions from the far reaches of our solar system, and she will give you an equally emphatic "Yes!"
That too. At home, the background hum of traffic outside, the hum of the refrigerator in the kitchen, and the soft hiss of air-conditioning or heating ducts is louder than the thermal noise from any of my guitar amplifiers.
Much the same thing is true at the small music jams I go to.
The situation is probably very different for extremely loud bands playing music genres that require high gain, high distortion amplifers, in front of very large crowds. Guitar amplifiers are never quiet enough for that. A "noise gate" is invariably part of those signal chains.
Replace the input stage triode (valve) with a JFET selected for low noise voltage, and replace Leo Fender's input stage 34 kiloohm "grid stopper" with something like 10k, and you get slightly better noise performance.
Keep in mind that the last 90 years of electric guitar music - all the great hits that billions of people have enjoyed for decades - have all been created with amplifiers that weren't designed for the lowest possible noise floor.
There are very few valves still in current production, so at least 99.9% of the time you will find a 12AX7 dual triode (same as European ECC83) in the input stage.
AFAIK, the 34 kiloohm grid stopper Leo Fender choose to place at the input of his designs generates more thermal noise than the actual triode valve that follows it.
And the up to 140k resistive source impedance of the guitar itself generates far more thermal noise than that.
Again, most of our favourite guitar-driven music of the past 90 years has been created with guitar amplifiers that were not optimized for thermal noise. At first they weren't optimized for anything (maybe low cost). Later they were optimized to produce a sound that the performer would like. Noise floor likely wasn't a consideration.
Think about all the great music that people listened to on hissy, scratchy shellac records, then on vinyl LPs, 45 rpm singles, and hissy tape and cassette recorders. Think about all the great music people enjoyed over hissy AM radio links on radios that reproduced nothing above 5 kHz and nothing below 100 Hz.
Noise floor is the sort of thing a non-musician (an audio engineer, say) would obsess about. Most musicians priorities are elsewhere. Better to have good music and a poor noise floor, than the other way around.
I have a foot in each camp (engineer / musician), so I am aware of both sides. Speaking as an engineer, lower-noise guitar amps are nice. Speaking as a musician, that's not a particularly pressing priority.
-Gnobuddy
A lute always sounds like a lute. It is a pretty sound, but has a limited scope.
An electric guitar is possibly the most versatile musical instrument humankind has created to date, and it can produce a range of sounds and timbres that no other instrument can (many of which were never imagined by the people who originally created the instrument.)
This is possible almost entirely because of the interaction between the e-guitar and its (nonlinear) amplifier, and/or effects units. That interaction is controlled by the guitar volume and tone controls, as well as by other controls.
When you're plugged into a valve guitar amplifier, the guitar volume control is also a distortion control. As you turn up the volume, you drive the amplifier further into nonlinearity, changing the timbre as well as the loudness.
Not every electric guitarist uses the volume control well (or at all). The really good ones do, though, especially in blues, pop, rock, and other genres that use some distortion (but not crazy amounts of it).
The best way I can show you what that actually means in practice is by linking you to a couple of videos:
1) Here's Joe Bonamassa demonstrating a range of very different sounds from a Les Paul:
2) Watch Zakk Wylde's right hand repeatedly drop to the guitar controls during this lovely instrumental ballad:
Did you notice what Wylde was doing each time he touched a volume control? If not, listen to the clip again, this time paying more attention to the timbre of the guitar.
Wylde uses the volume control throughout the piece, in order to very gradually and progressively change the sound of the guitar, increasing the amount of distortion in the sound as the song moves from its gentle intro towards its emotional, driving peak.
He also varies picking intensity, tempo, the note-lengths he plays, and the intensity of his string-bending (vibrato in classical terms) to achieve the same result: the song builds from a gentle start to an intense and emotionally gripping peak. The guitar volume controls are one of a range of tools he employs to create the desired musical effect.
-Gnobuddy
I remember seeing him featured in various Fishman ads when they first released their Fluence pickups.
Just to be clear, I wasn't trying to "diss" them in any way.
I know nothing about the size of their market, but have never met a musician who uses them. Most of the musicians I know are amateurs like me, which may have something to do with that.
Perhaps the Fluences are more popular among studio guitarists, who are more likely to obsess over a lower noise floor and guitar sounds that are more robust and not susceptible to varying with cable length, effects chain order, and so on.
-Gnobuddy
The funny thing is that you seemed to be worried about the noise of translinear circuits, or any circuit that works with low signal voltage levels, in your unwanted clipping guitar amp thread, even though translinear variable gain amplifiers were used all over the place in 1990's broadcast mixing consoles (at least in the ones that were still analogue).
Last edited:
You stated in an earlier post that you don't notice the noise of the guitar volume control because of the high noise floor of the guitar amplifier. You just argued that both the input triode and grid stopper produce less noise than the guitar volume control, which makes sense, but if that is the case, then what does dominate the noise floor? Apparently there is something somewhere producing even more noise than the volume control potmeter inside the guitar.
By the way, regarding lutes and electric guitars, I once heard John Dowland's lute song Flow my tears arranged for a male and a female singer, harpsichord, synthesizer and electric guitars. It sounded quite good.
No, I didn't get that impression. I was actually inferring from what I've seen from users and their length of time in the marketplace that there must be enough demand. In support of your comments, it seems to me the vast majority of pickups being sold on the market are standard magnetic pickups, and there's a huge market for all interpretations of PAF, original Strat, Tele, etc. Seems many guitar players are always chasing new sounds with pedals and amps, while using the same guitars that made modern music famous.
I've got so many guitars now, and they all have their own pickups and sound. Same with my amps. I've got some higher-gain amps (not as high as today's metal-genre amps) and lower-gain amps. Basically, every decade's worth of popular tone and distortion from the 1960's to the 2000's. My playing is no longer up to the high quality of my gear anymore, alas...
Yes.
What I actually said - or tried to say - is that - with the amplifier input shorted to ground - the input stage grid stopper resistor value Leo Fender settled on dominates the noise performance of the entire amplifier. It's noisier than the input triode. On paper, anyway.
For me, it's almost always ambient room noise. Traffic on the street outside, heating / ventilation ducts in our apartment, the refrigerator in the kitchen, etc.
If we include non-stochastic (i.e. deterministic) sources of noise / interference, then, as GKTAudio said, hum and electrical noise pickup from single-coil pickups tends to dominate. (Again, I'm speaking of my personal experience.)
No, I think this was a misunderstanding on your part.
-Gnobuddy
The focus of that thread is ENTIRELY on undesirable clipping behaviour of high-negative-feedback amplifier circuitry when an electric guitar is plugged into it. It's right there in the title of the thread.
If you came away with a different impression, you misunderstood the thread.
There may have been one or two posts about noise in the thread, sure. But that was never the focus of the thread.
Yes, noise performance is important: we don't want worse noise performance than Leo Fender's 1940's amplifier designs, do we? That is quite achievable with solid-state circuitrythrough bad design.
For example, using a uA741 op-amp at the input stage would probably do the trick - it would be worse than a 1940's Fender amp in every way, including noise!
-Gnobuddy
AFAIK, carbon composition resistors consist essentially of a pinch of fine carbon granules pressed together in a lump and painted over.
They produce vast amounts of excess noise, along with poor stability (the value drifts dramatically over time).
Personally, I don't see their appeal. I have never used a single one in any electronics device I've built, nor do I plan to ever use one.
Your comment about where excess noise inside a guitar might come from (if in fact there IS excess noise) is an interesting one, though. Thinking about it, I don't know much about excess noise in potentiometers, nor do I know what type of materials are used to make the internal guitar volume potentiometers. My guess is that they're mostly carbon or conductive plastic types these days.
My first guess is that the relatively low-pressure contact between the potentiometer track and the potentiometer wiper probably does generate excess noise, in the same way that the low-pressure contacts between carbon granules in a carbon composition resistor does.
Once again, this is only a guess at this moment - I haven't looked for any data to confirm or invalidate the hypothesis yet. I just got out of an all-day meeting, and my brain is too fried to look into this any more right now.
-Gnobuddy
As it turns out there is another source of hum in a Blues Jr. It is stray magnetic coupling between the power transformer and the output transformer. There is fix, which I verified using my own Blues Jr. It involves putting a piece of steel sheet metal between the two transformers, and varying its position to find the maximum hum null, then fixing the plate in that position. Sometimes used on those amps to be used for recording. Mentioned it once before at: https://www.diyaudio.com/community/threads/fender-blues-jr.322222/post-5425331
I'm sitting back and enjoying the music posted in this thread. YT audio grade, but still enjoyable ;')
Fortunately, resistors can only add 1/f noise to the noise floor when there is a bias current flowing through them. That's because their 1/f noise manifests itself as random resistance variations. In fact, if anyone ever finds a resistor that produces more than just thermal noise without needing a DC or AC bias, it is of great importance to physics, because it violates the second law of thermodynamics.
At least in ordinary amplifiers, potmeters do not normally have DC bias currents flowing through them. Trimming potmeters for setting quiescent currents in solid-state amplifiers are an exception, but they are way at the end of the signal chain.