You can think of an amplifier as a unique combo of "ingredients" that, like cooking a dish, come into play in achieving its "flavor". Why so many amps? Same reason as Ben and Jerry's "flavor of the month"...
What's an example of an "ingredient"? No 1 that I can see is the Fender Tone Stack. You can find it in any Fender schematic - plus in most others too. Why? Same reason as why no knock off would build a guitar that doesnt look just like a strat or tele. As common as those body shapes are to see, that particular tone control topology is as common to hear.
Another ingredient are elements that waveshape. Put a signal though an amplification stage consisting of a 12AX7 triode, what comes out is that signal with a tonal color infused into it, as the stage will introduce some distortion. Strap two 12AX7 triodes in parallel; a different color comes out, due to a different distortion. This is before overdrive; the signal is still relatively "clean".
Another ingredient is a transformer. They dont just boost or cut voltage without adding in a little color of their own, in terms of distortion.
Then, when you enter the world of overdrive (deliberately cranking volume far beyond clean gain levels) even more "ingredients" come into play. How does the waveform distort; is it symetrical or just half of it gets clipped-off? That's one. Does the waveform edge go straight up, hit a perfect 90 deg bend, then go straight across - or are there rounded off corners where it makes the bend. That's one.
Then there's ingredients that effect the dynamics. Like the so called "loudness wars" in music recording, guitar players discover than an amplifier that bends a little dynamically - often attributed to power supply collapse - sounds louder than their rock-solid counterparts. It's the very same reason why compressed musical recordings sound louder particularly over constant background sound levels. Every guitar player wants that, as they are competing in the same sonic space as the bass, the drummer, the singer, the organ / keyboard.
Then you get into how dynamic the distortion is, which is - I'll guess - something that's an attribute of the combined ingredient signal chain. One time so many years ago - we were literally using ASCII terminals - I read on a company internal forum about a j-fet design someone did, evaluated by another player. He said he could get it to "bark" (I assume like a dog) and he expressed surprise that someone could get fets wired up in a particular way to do that - when he had only previously ever heard that kind of response from tubes.
Of course, in this "ingredient" line of thinking, the speaker is simply another. Yet, how the speaker is allowed to effect the amplifier's sound is yet another ingredient of the amplifier! The amplifier can have a "stable into any load" like a laboratory power supply would ideally be, or it can bend a little in its sonic behavior, depending on what's hooked up as a speaker. The kicker is, sometimes you want it to sound the same, with only the speaker's color changing things, sometimes you want it to interact more with the speaker.
I use the term "color" in part as tribute to the late great EVH, who'd set up the amplification for his guitar to sound "brown". I dont know how the term originated, nor whether it has anything to do with the colors assigned to noise types, white, pink, red, blue - etc. The story I find so amusing is he bought an amp - all the way from the UK. Cut off the plug, wired up a US standard and plugged it in. It made a sound, which I must assume he liked. Turns out the amp had an operating voltage selector, which, as it was sent from the UK, was set to 220, while he was running it off 110. So then he's off with using Variacs on his amplifiers AC input, to try to get whatever it was he heard from that amp, at live shows. Trying to get them to sound, as well, "brown". Whatever that means.
So if you're going to be an amp designer, you need your spice rack of ingredients you can successfully pull from. You mix and match what and levels thereof to "taste" as you would in cooking; of which, hopefully your customers agree "this is good". Put the "frills" over the top of that; Reverb, Tremolo, Channel switching, Effects loop, Headphone, Ext Spkr Output and you have a guitar amp design. As long as it all works together successfully. Easy, right?
So collect up your ingredients and learn how to use them, element by element. Like an flavoring. some will compliment, some dont go together at all. Sonically, that is.
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For that little POS. I cant wait to see the auction close, so I can have a good chuckle. I used to tease about the over enamourization with tubes 30 years ago, but now it's really ridiculous, surpassed only by $ itself as far as what people will get on their knees for.
I have no hope of ever finding anything to even play with anymore, as soon as anyone finds one in the wild, up on the pedestal it goes, 1000ft high!
Do really guitar amps sound different?
Yes indeed ! Just like for guitars and players...
1/3 for the Player.
1/3 for the Amp.
1/3 for the Guitar.
Remember just that an Audio amp doesn't shares the same sonic qualities as a Guitar amp... These are two different worlds, even if they share many common parts !
You can see some of my builts here, with tone samples : https://guilhemamplification.jimdofree.com/
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Salue @tubelectron
If we put aside the guitar and the player, how much the speaker plays roll for the final sound.
How do you choose your speakers?
It looks that dsp has already invaded the guitar preamp effect world. Fender has a tiny plug in the guitar jack and can do everything, tone control, reverb, saturation and transmit on bluetooth. The Fender mustang micro for $100.
I have more and more conviction that the power amp should be only head, make use of inductive discharge with double transformer push pull class A in current mode. It can be switched to double single with polarity reversal possibility. It can have all needed adjustment on the feedback to allow the musician tune the sound of the amp to his speaker that HE chose. As I showed the tube radio, it is possible to provide adjustable notches to decrease at will the standing waves on the diaphragm, it can be adjustable bias of the class A to give dissymetrical compression, that is intervene only in the amp-speaker conversation I/V channel.
I have more and more conviction that the power amp should be only head, make use of inductive discharge with double transformer push pull class A in current mode. It can be switched to double single with polarity reversal possibility. It can have all needed adjustment on the feedback to allow the musician tune the sound of the amp to his speaker that HE chose. As I showed the tube radio, it is possible to provide adjustable notches to decrease at will the standing waves on the diaphragm, it can be adjustable bias of the class A to give dissymetrical compression, that is intervene only in the amp-speaker conversation I/V channel.
It really depends on your sonic references. While including some effects in an amp could be a good selling point, it negates the flexibility of a "diy" pedal board. Exploring further, an amp simulator on a laptop can also be an option. I tried the Amplitube and found it quite nice. And, AFAIK, John McLaughlin does it all the time, guitar -> laptop -> soundboard.
Me, I'm an ancien relic, and my references are Clapton during the Cream era, SG Standard straight into 2 full stack Marshall, everything up full. Of course this is strictly illegal nowadays.
It's an important role - you indeed guess it - and that all what I can say, honestly...
A test with the matching amp will tell you. There are friends who like this speaker and other who dont, me included : we do not play the same way, not with same setting, the same guitars... So it is difficult to put the Guitar, the Player and the Amp aside.
I choose a speaker for a given amp, and test it with different guitars, at different settings and on different styles of music. So finally, it is rather a case-by-case basis... Of course we all know the particularities of this and that speakers. For example :
- The EVM12L is a huge, loud, heavy and straight speaker, it stay straight even presented with overdrive, can handle a lot of power, produce high loudness, and still stay straight no matter. I use it in my Serial Tone Killer amp, which is a dual channel amplifier :
The EVM12L give that amp THE big tone I expected to meet his specs, but the amp by itself must be good sounding - if I can say so - because the EVM12L is straight, and so will restore the sound as it is, at any loudness... That's why it's not a very favored speaker to the guitarists, in addition to its anvil weight of 9kg !
- For the restoration of my little Danelectro DM-10 from 1964, I went for a 8" Jupiter AlNiCo speaker, which gives this amp the cool / nasty / dirty tone it deserves...
- For my Boogie MKIIA from 1980, I choose the ALTEC 417-8H loudspeaker, for its violin tone when presented to overdrive, often associated to Carlos Santana (the 417-8H is reputedly his favourite speaker) :
- The Jensen speakers (Ceramic or AlNiCo) are often considered scooped, bassless and trebly - and this can vary from one sample to another... But they are marvelous notably in the 40s-50s amplifiers (Valco and Gibson, etc...), which had simplistic tone correctors, and often lack brilliance, while offering a bassy-midrangey tone which can turn to a muddy-farty overdrive tone . The Jensen P10R or P12R can reveal then an excellent good guitar tone with this kind of amps - below on a 1948 Magnatone restoration / modification, with its original 8" Jensen P8T speaker :
And of course : there are notable exceptions !
@Zung : we are probably from the same batch !
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Well, almost everything. Sounding like a real tube amp is most likely something it can't do all that well.
Apart from obvious filters, there are differences in the sound of an amplifier.
1. Negative feedback, if yes, how much, what kind?
2. Operating the amplifier at the power limit, then the clipping behavior and possibly the drop in the voltage supply (compression) contribute to the sound quality.
3. Transformer distortion/coupling capacitor distortion
Thank you @HAYK !
Actually, none of my amps are "commercial products" per se : I am only an amateur builder (audiophile and player), and do part-time servicing, repairs and restoration works for local music and luthier shops friends, and also customers who own valuable items, who come by "word of mouth" or recommendations.
Below, three restorations : two Fender Bassman 6G6 and one Marshall JTM45, from 1964-65.
In the past, yes I had numerous demands for orders, so I had to state the situation clearly on my little website ( https://guilhemamplification.jimdofree.com/ ) :
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with guitar and bass guitar output tranformers - is Ok - perhaps wise to design with less primary inductance than hi-fi application - that typically results in less weight. I had some custom transformers made by Pacific which weighed maybe 10-11lb and spec at 280W down to 40Hz to run on six-EL509pp. Then there's just plain cheap like the 2lb of less transformer on the old Silvertone twin 12. My Traynor YBA3 Custom Special sounded pretty loud on a 6x10 Traynor "bass" cabinet.
Millerioux has been bought in the 90s by the company SERDI, ( https://www.serdi.fr/ ) but do they build and sell STS Millerioux transformers still today ? Not sure... Maybe on special order. The original Millerioux factory was located in Romainville, near Paris, which is not the location of SERDI, and there's no mention of Millerioux transformers on their site.
Monmagnon still build Audio transformers on special order, AFAIK : an Audio friend of mine ordered some a few years ago directly from him.
I had several MIllerioux OPT in the past : AH50B, AH26B, H34BN, BH5B, HH25B... Some traded but most bought from the Millerioux factory (I always had Mr Pierre Millerioux on the phone when placing my orders...)
My Micro-Amp uses a pair of BH5B :
My U-300B uses a pair of HH25B :
My Paul GUILHEM Deluxe uses a H34BN :
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These are the fundamental harmonics. Do not mistake these with the harmonics that are pre-dominant, specially at the low notes. It turns out that for the electric guitar anything below 150~200Hz is irrelevant to perceived sound, but eats unnecessary power from the amp.