How fast is your guitar amp?

**Vladan** · 07-31-2016, 12:21 PM

I hope Vintagelove will chime in, I surely won't be giving any more "lessons", just let me remind you, the fundamental freq of the highest note one can play on an usual guitar, say E on the 24th fret of the 1st string, is 1.31851kHz. Also, as seen in Destinytot's clip, to him at least, the effect was clearly noticeable at quite low volume/level. Switching to lurking mode, bye!

**KirkP** · 07-31-2016, 01:47 PM

For the techies, here's a dated but fascinating article by Peter Baxandall (inventor of the tone controls used on most hi-fi audio equipment).
http://www.keith-snook.info/wireless...%20mystery.pdf
He argues that all amplifiers sound the same if they are correctly designed and operated within their power limits for linear operation. He discusses the need for blind testing and equalizing volume levels when comparing audio equipment. He shows how to set up a system to subtract the original signal from the amplified signal to listen to hear only the distortions isolated from the music. (These ideas are still controversial among those in the boutique audiophile industry, but let's not go down that rathole in this thread.)

Baxandall assumes the user wants minimal distortion and will select an amp with enough power to always operate within the linear region. This is rarely the case for guitarists using magnetic pickups. We typically view the amplifier nonlinearities as part of our sound -- the guitar and amp work together as a single instrument. Still, it would be interesting to try Baxandall's subtraction method for a guitar amp to hear only the distortions. One might learn a lot about what makes one amp preferable to another.

P.S.: I like the Bertrand Russell quote he starts with - "Some things are believed because people feel as if they must be true, and in such cases an immense weight of evidence is necessary to dispel the belief."

**Skip Ellis** · 07-31-2016, 02:09 PM

And I'll bet 'zebra' coil humbuckers sound better than the black ones.....or is it the white ones? Can't tell - too busy trying to measure the speed of my amp!!

**Boston Joe** · 08-01-2016, 09:37 AM

Originally Posted by KirkP

For the techies, here's a dated but fascinating article by Peter Baxandall (inventor of the tone controls used on most hi-fi audio equipment).
[...etc...]

I think audiophile stereo stuff is a much different animal from guitar amps. Those things are designed to reproduce sounds from recordings with as much fidelity as possible. Guitar amps, not so much. People want an amp (aside from modelling amps) to have their own personalities, and distortion qualities are desired. (Even when you're playing a clean amp, you're going to get a bit of distortion from the speaker cone, cabinet, etc.). I've never heard anyone say they like a stereo amp with a bit of sag.

**MarkRhodes** · 08-01-2016, 09:55 AM

Originally Posted by KirkP

P.S.: I like the Bertrand Russell quote he starts with - "Some things are believed because people feel as if they must be true, and in such cases an immense weight of evidence is necessary to dispel the belief."

I like that quote too.

**Generalmojo** · 08-01-2016, 12:03 PM

Originally Posted by Boston Joe

I think audiophile stereo stuff is a much different animal from guitar amps. Those things are designed to reproduce sounds from recordings with as much fidelity as possible. Guitar amps, not so much. People want an amp (aside from modelling amps) to have their own personalities, and distortion qualities are desired. (Even when you're playing a clean amp, you're going to get a bit of distortion from the speaker cone, cabinet, etc.). I've never heard anyone say they like a stereo amp with a bit of sag.

I used to think that audiophile stuff was snake oil. One of my students dads was always talkin about this stereo system that he had been putting together. Thing is worth, I kid you not, over $300,000. I'm thinking whatever dude. Until one day when he sat me in front of it. It wasn't like being at a concert. It was like the band was playing in the room. For us and only us. You could hear the body of the acoustic guitar a little to the left and he neck a little to be right. Where the hi hat was compared to the snare drum. You could hear the drummer breathing a little at some points. And it was a song I had been listening to me whole life.

Anyway, those components are "fast." And accurate because that's what he's going for. Accurate. Not really going for that with my amp. Otherwise I'd just plug my tele into the PA. Direct. Like some archtop players do. But nope. I want coloration and sag and all the goodness that goes along with it. And then he audiophiles can record it and brag about how accurately they captured it.

Sent from my iPhone using Tapatalk

**vintagelove** · 08-01-2016, 01:40 PM

Originally Posted by Vladan

Apologies accepted.

I certainly never did such comparison. I don't quite get "studio setting" variable, though. You were (un)soldering components of an amp circuit to check the impact on sound?
Unless there was some seriously set up test table in that studio setup, the time period btw two possible amp setups would yield any observation on sound quality more less irrelevant, except for the most obvious ones. Same for "responsiveness".

Now, I never said there was no experienceable difference btw different amps, i said what is being experienced is not the speed of an amp. All amps pass the signal equally fast. if we would have to remain in op amp domain, applied to typical guitar sound envelope, recovery time is of more importance than slew rate.

in the end, it's all down to ears, fingers, brain and feedback, ie. psychoacoustics.

if I had to put my money on what in an guitar/ amp combo lead to behavior as observed by player, it would be input sensitivity and impedance matching btw guitar output and amp input, as well as btw various stages (as in functional parts) of an amp, combined with frequency range of the signal and ear sensitivity of player.

Again, it's nothing about speed. Think this way, how long does it take for a hammer to hit the string after the key's pressed on an piano and do you experience any delay?

it was actually quite simple. You may be familiar with the 5534 opamp? Well it needs external compensation to remain stable(at certain gain levels). I replaced it with an ma332 which is internally compensated. As a result, the external cap (that limits the speed of the amp) was no longer needed. I simply snipped the cap, and all of a sudden the transients started leaping through the speakers. I literally couldn't believe the sound.

also, power supplies make a huge difference in the speed of an amplifier.

Here is the bottom line gentleman (and ladies). The speed of an amplifier refers to the ability of the amp to deliver the electrons it is being called for at the moment, and results in a change in feel and dynamic range (it's not like notes are going to sound a half second after you play them, that's just silly). There is simply no way that a super reverb circuit can deliver the same immediacy that a dumble circuit can. If you have never sat down with an amp of this type it's quite an eye opener. A super reverb can go from 5-50, because of the power supply design (and especially tube rectifier). I liken it to playing into a nice comfy pillow. You can do no wrong. A dumble circuit can go from 0-100. If you dig into a note, it can be painfully loud in relation to the note before it. I likened it to a cannon attached to my picking hand.

Two quick things,

First, remember George came up most likely playing these low headroom (compared to a twin), tube rectified amps. Even a twin is on the medium scale of "fast amps" compared to a dumble or a redplate. However it must have been refreshing for him at the time to move to the twin.

Here is what I find interesting, for playing bebop, I much prefer the slower amp. When you're playing really fast, you're trying some half impossible thing, sometimes you have to dig in, or you accidentally dig in. I prefer having that nice "pillow" to play into (if I'm playing bebop, blues is a totally different thing). Remember though, a twin still has a bit of that softness. It's much of the reason I dig a polytone.

Again, unless you have played one of these amps, I can totally understand not getting it. Go to a guitar store, plug into a dumble clone, and spend that first few minutes wondering wtf is going on with your technique. After a minute you'll adjust and understand exactly what I'm explaining.

**vintagelove** · 08-01-2016, 01:44 PM

Originally Posted by Generalmojo

I used to think that audiophile stuff was snake oil. One of my students dads was always talkin about this stereo system that he had been putting together. Thing is worth, I kid you not, over $300,000. I'm thinking whatever dude. Until one day when he sat me in front of it. It wasn't like being at a concert. It was like the band was playing in the room. For us and only us. You could hear the body of the acoustic guitar a little to the left and he neck a little to be right. Where the hi hat was compared to the snare drum. You could hear the drummer breathing a little at some points. And it was a song I had been listening to me whole life.

Anyway, those components are "fast." And accurate because that's what he's going for. Accurate. Not really going for that with my amp. Otherwise I'd just plug my tele into the PA. Direct. Like some archtop players do. But nope. I want coloration and sag and all the goodness that goes along with it. And then he audiophiles can record it and brag about how accurately they captured it.

Sent from my iPhone using Tapatalk

Ding ding, we have a winner!!!

Its funny, the better the amp specs on paper, the worse it is for a guitar amp. We like the coloration, sag, distortion, limited frequency response, etc. Seems counterintuitive, but it's the truth.

**Boston Joe** · 08-01-2016, 02:27 PM

Originally Posted by vintagelove

Ding ding, we have a winner!!!

Its funny, the better the amp specs on paper, the worse it is for a guitar amp. We like the coloration, sag, distortion, limited frequency response, etc. Seems counterintuitive, but it's the truth.

Right. We call it "personality" or "soul" or "mojo" or something like that.

**Vladan** · 08-01-2016, 03:14 PM

It's hardly a miracle to have more hi freqs and transients once you remove lo pass filter, however, that filter was not there to slow your amp, it was there to let only those freqs pass that your instrument can produce, or to cut off the garbage not produced by your instrument, but occurred as an artefact of poorly designed amp. You can just the same plug into an Hi Fi amp, preferably after some impedance matching and treat signal with some filters EQ and compression. Then treat it some more to compensate for limited range speaker as usually used in combo with guitar amp. Speaker, of course, is not part of an amp. If it was, then the air, walls, people, guitars, cables, preamps and EQ stacks would also be. So, as I said in that previous thread, you can trust manufacturers and treat their poor designe as something god given, or you can start from something as neutral as possible and make your own choice. The best compromise approach is to think of it as of an default half useful preset.

if there was some character and mojo there, we would not be here talking.

I hate loudness , I want my sound, even if highly distorted, dialed at low level then accurately reproduced at level suitable for the audience. I want to set my EQ, compression, saturation ... I don't want to rely on someone's poor design artefacts will do that for me.

Again, the very idea of an amp is to pass the signal clean, it does not matter at what stage and by what means you will distort it.

Sent from VladanMovies @ YouTube

**Boston Joe** · 08-01-2016, 03:21 PM

Originally Posted by Vladan

I hate loudness , I want my sound, even if highly distorted, dialed at low level then accurately reproduced at level suitable for the audience. I want to set my EQ, compression, saturation ... I don't want to rely on someone's poor design artefacts will do that for me.

Can't do it. The frequency response of your ears changes with volume level.

**Vladan** · 08-01-2016, 03:46 PM

Originally Posted by Boston Joe

Can't do it. The frequency response of your ears changes with volume level.

Yes, response changes, but I can compensate accordingly.

**KirkP** · 08-01-2016, 04:10 PM

If anyone thinks my Baxandall post was trying to argue that guitar amps should be designed for hi-fi, they didn't read what I wrote very carefully. I was just pointing out there are things to be learned from the hi-fi community. (But there's also plenty of bunk among audiophiles.)

**Vladan** · 08-01-2016, 04:15 PM

it's all about money. There are salesmen and there are buyers. Salesman will always try to sell you multi thousand $ amp, so you could have some new mojo sound, even if all you need is a different EQ setting. My posts are mainly about that side of the story.

**KirkP** · 08-01-2016, 04:50 PM

Originally Posted by Vladan

it's all about money. There are salesmen and there are buyers. Salesman will always try to sell you multi thousand $ amp, so you could have some new mojo sound, even if all you need is a different EQ setting. My posts are mainly about that side of the story.

I tend to agree that's often the case in the audiophile community, but I don't want to throw this topic off the rails to argue about audiophile issues.

The situation is different for guitar amps though. Guitar amps (at least those designed for magnetic pickups) are designed to intentionally be non-linear. EQ settings can give you a great range of tones, but they can't duplicate the effects of non-linearities. I'm not just talking about clipping, but also the more subtle effects like sag, push-pull crossover distortion, etc. Guitar speaker systems (cabinets and drivers) are also highly non-linear, which is why guitar amps and speakers are often sold as a system.

For both hi-fi and guitar, one of the most important factors in tone is the room, and positioning of the speaker within the room. EQ settings are really critical there, but so are other factors like speaker positioning. That topic could be a whole new thread.

**Generalmojo** · 08-01-2016, 07:57 PM

Originally Posted by KirkP

If anyone thinks my Baxandall post was trying to argue that guitar amps should be designed for hi-fi, they didn't read what I wrote very carefully. I was just pointing out there are things to be learned from the hi-fi community. (But there's also plenty of bunk among audiophiles.)

I think that's just where the conversation ended up going. Thanks for putting us back on track, though.

Sent from my iPhone using Tapatalk

**Thumpalumpacus** · 08-02-2016, 02:57 AM

Originally Posted by vintagelove

Ding ding, we have a winner!!!

Its funny, the better the amp specs on paper, the worse it is for a guitar amp. We like the coloration, sag, distortion, limited frequency response, etc. Seems counterintuitive, but it's the truth.

Indeed. We're so accustomed to playing the amp as well as the guitar we don't really notice how we're doing exactly that. It's a big reason why I love playing acoustic, because it brings me back to the fingers -- how you touch the instrument.

A solid-state hi-fi amp will reveal too much, sometimes, of the magic, when we, and the audience, simply want to say, "wow." It's like being sidestage at an illusionist's act. It's why I prefer tube amps; not for the tone (because SS amps can reproduce tube tones pretty damned well nowadays) but because I interact with the feel of the amp, and that definitely influences how I play.

**Thumpalumpacus** · 08-02-2016, 03:04 AM

Originally Posted by Vladan

Speaker, of course, is not part of an amp. If it was, then the air, walls, people, guitars, cables, preamps and EQ stacks would also be.

They are all part of the signal chain. I dial my amp in to the room; I use different strings on different guitars. The goal is to get the sound in my head out to the ears listening. Fetishizing this or that section of the signal chain doesn't work for me (except for power tubes, lol) doesn't get me where I'm going. Using my ears has usually gotten me closer to the goal.

The amp is very important, but you and I both know the same amp and the same settings can sound different from day to day.

**Generalmojo** · 08-02-2016, 07:07 AM

Originally Posted by Thumpalumpacus

Indeed. We're so accustomed to playing the amp as well as the guitar we don't really notice how we're doing exactly that. It's a big reason why I love playing acoustic, because it brings me back to the fingers -- how you touch the instrument.

A solid-state hi-fi amp will reveal too much, sometimes, of the magic, when we, and the audience, simply want to say, "wow." It's like being sidestage at an illusionist's act. It's why I prefer tube amps; not for the tone (because SS amps can reproduce tube tones pretty damned well nowadays) but because I interact with the feel of the amp, and that definitely influences how I play.

The feel. Yes, yes, yes. This is way more important than the sound of the amp to me sometimes. How does it react to my playing? It's like driving a car. I notice then when using someone else's amp. It takes a while to get used to how tight or loose the steering wheel is. The breaks are a little more sensitive than I'm used to. Whoa. The gas pedal you don't have to press down so much. Okay. This clutch is a bit squishier. Where's the damn windshield wiper thing?

Once I figure it out, I start to drive like myself a little more. But at first the feel of the car makes me drive like a grandma. And it's a little embarrassing.

Sent from my iPhone using Tapatalk

**mercosound** · 08-02-2016, 06:31 PM

I admit I've never considered the concept of fast/slow amps. I can almost see how slew rate could affect the perception of speed. Slew rate is both frequency and amplitude (voltage) dependent; a lower slew rate is generally thought to limit the distortion-free signal level that an OP Amp can put out. That being said, I have seen (on a scope) low slew rate devices round off the corner of the leading edge of a square wave; I suppose that it can noticeably reduce transient response, which may likely be perceived as a slower amp. Since slew rate distortion is dependent both on frequency and amplitude, you might expect the effect to be more noticeable with loud, higher pitched notes...

Personally (although with no firm knowledge/figures to back this up), I would think that the mass/stiffness of the various parts of a speaker would exert a more telling effect on the "speed" of an amp - physical inertia being a well understood/accepted concept. Along those lines, I've often referred to microphones with very low mass diaphragms as being "fast" mics. The lower mass of the diaphragm means that there is less initial inertia to overcome, and the transient response is better. Is it truly a faster mic? Are some amps truly faster that others? Interesting question; it's got me thinking of things electrical that I haven't thought about in years (decades?). Good thread.

**Guitarbean25** · 08-02-2016, 07:19 PM

If you want a "fast amp", try a high gain monster...some have beautiful clean sounds...others call them sterile...I call it fast and unforgiving. I'm a fan!

A Reeves Space Cowboy will get you there. AMAZING crazy beautiful cleans.

**entresz** · 08-02-2016, 07:21 PM

I've always found the Roland JC-120 to be a very unforgiving amp. I have a bit of a love/hate relationship with them. Some of the best sounds I've had have been through them, but so have some of the worst!

**Generalmojo** · 08-02-2016, 07:43 PM

I play everything including jazz through a .... Wait for it... Gasp! A Mesa Boogie! Honestly. Such nice cleans. People always think of metal and high gain. Their clean is amazing, in my opinion.

Edit: almost forgot my point. Another unforgiving amp. You can hear a lot you can't on other amps. But it makes me a better player.

Sent from my iPhone using Tapatalk

**Greentone** · 08-02-2016, 11:19 PM

JC120 = very good clean amp. 25 years ago I used to gig with one and liked it for cleans.

**Thumpalumpacus** · 08-03-2016, 03:00 AM

Originally Posted by Generalmojo

I play everything including jazz through a .... Wait for it... Gasp! A Mesa Boogie! Honestly. Such nice cleans. People always think of metal and high gain. Their clean is amazing, in my opinion.

Edit: almost forgot my point. Another unforgiving amp. You can hear a lot you can't on other amps. But it makes me a better player.

Sent from my iPhone using Tapatalk

Depends on the Mesa you're talking about, but yeah. Some Mesa cleans are better than others.