Maybe not too obvious, but having seen Pink Floyd in concert 5 times, I picked it up. There are several YouTube videos that discuss how Gilmour gets his signature guitar sound, and they do not agree. Much of it comes down to playing style.
I used to hang out at the Lafayette store in South Miami as a kid because the manager let me play the guitars. It was also next door to the slot car track where I spent most of my money. It was 1966 and I was 14. I would wind up working for the competition (Olson Electronics) a few years later (1970 - 72).
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I remember when widely popular music in the 80's was awash in chorus, digital delays and reverb...then we got to the 90`s grunge trend and guitarists stripped it down to a much more basic overdrive/distortion sound, I think that was developing from the 70`s punk movement. Do I like fuzz pedals? Yes but it`s more how they have been used in song to great effect (pun intended) by some guitar masters..not an ''always on pedal'', but pretty essential to some material. Surf music and rockabilly pretty much need slap-back echo and spring reverb (and maybe some tremolo) as an integral part of the electric guitar sound.
Getting back to amps, for me a built in spring reverb and possibly a tremolo pretty much in the vain of a Fender style best fits my style and preference of playing. All the other extra effects, I prefer separate stand alone pedals.
20 to 30 Watt seems like enough to get by on most situations (mic'd up to the PA if required). Too much guitar amp stage volume causes a lot of potential issues, and is a pain to deal with when you`re the sound guy/gal.
Remember the ARP / Solina String Ensemble? It first appeared in the mid 70's on a few records. Within less than a year it was everywhere. You couldn't turn on the radio without hearing one. Soon Ensemble burnout occurred, and they became monotonous and irritating. I took a first gen ARP string ensemble apart to see how it worked. Hidden inside that expensive wooden box was a simple IC chip organ, a top octave generator chip, 12 divider (flip flop chain) chips, some simple analog voicing filters, and the "ensemble effect" circuit which changed on every different version of the keyboard. The first gen had three ORB-33 BBD chips and clocking circuit comprising of a couple logic gates, all configured into a chorus effect. This circuit evolved with each generation to keep up with the chorus chip sets of the day. I built a clone version with parts from Radio Shack!
Every sound has its day, then it goes away.......sometimes it comes back again another day.
When I build the "last guitar amp" it will have a reverb tank, and probably tremolo. Somewhere in the path from input jack to speaker jack there will be a Voltage Controlled Amplifier. The VC input will be connected to the DAC output of a Teensy SBC module. Tremolo, compression, envelope modification and all sorts of other FX can be done easily and changed at will by reprogramming the Teensy. The VCA already exists on a breadboard, and I have built two complete "virtual analog" synths with pots. encoders, and a Teensy module feeding a 16/44 stereo DAC. Some of that tech will wind up in a guitar amp. Any internal FX will be on a separate PC board that can be easily swapped or bypassed.
I'm probably looking at two preamp chains, or one with serious morphing capability depending on which is simpler and more reliable. I once had a guitar amp that had two power amps. Each was voiced differently with different OPT's the big sounding amp fed a 12 or 15 inch speaker. The smaller amp fed a 6 inch speaker. There was an "Ultraflex" knob to control the balance between the two amps. That thing had a bluesy tone that I can't make any other way. The cabinet with a 15 inch and two 6 inch speakers is about half finished. I'll probably have two power amps in the 20 to 50 watt range. The amp for the twin sixes might be SE depending on the outcome of some experiments that are currently underway.
Every sound has its day, then it goes away.......sometimes it comes back again another day.
When I build the "last guitar amp" it will have a reverb tank, and probably tremolo. Somewhere in the path from input jack to speaker jack there will be a Voltage Controlled Amplifier. The VC input will be connected to the DAC output of a Teensy SBC module. Tremolo, compression, envelope modification and all sorts of other FX can be done easily and changed at will by reprogramming the Teensy. The VCA already exists on a breadboard, and I have built two complete "virtual analog" synths with pots. encoders, and a Teensy module feeding a 16/44 stereo DAC. Some of that tech will wind up in a guitar amp. Any internal FX will be on a separate PC board that can be easily swapped or bypassed.
I'm probably looking at two preamp chains, or one with serious morphing capability depending on which is simpler and more reliable. I once had a guitar amp that had two power amps. Each was voiced differently with different OPT's the big sounding amp fed a 12 or 15 inch speaker. The smaller amp fed a 6 inch speaker. There was an "Ultraflex" knob to control the balance between the two amps. That thing had a bluesy tone that I can't make any other way. The cabinet with a 15 inch and two 6 inch speakers is about half finished. I'll probably have two power amps in the 20 to 50 watt range. The amp for the twin sixes might be SE depending on the outcome of some experiments that are currently underway.
You could make it P-P and cut to SE using the VCA on the drive to just one of the output tubes. If you did it for both amps, you could beat the original Ultraflex control by having it smoothly pan from SE on top to SE on the bottom, the opposite amp going P-P. Ultratone...
Ditto. It helps to be able to perform a good vibrato (or other embellishment) that goes with the groove of the music. Its in time, and with a congruent lilt in relation to the swing/groove.
Somewhere here someone mentioned a modular guitar amp and this came to mind... Duncan made a modular amp with swapable stages some time ago—their "Convertible" amp. I didn't look for schematics, no idea how or if they went beyond the FMV (someone else said this here too) formula/ethos but the idea is appealing to me anyway. I found a manual online.
This little test amp delivers 35 watts of SE power with HiFi specs using two TV sweep tubes. It can also do 30 watts with a single 4D32 transmitting tube. The current drawback is the 11 pound Hammond 1628 SEA OPT. I don't need response down to 20 Hz so I'll try some alternatives when I get a chance.
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This guy has a series of videos from about 6 years ago on the convertible with schematics.
I looked at this link when it was first sent to find that it was a Behringer multi FX Eurorack unit from Sweetwater Sound which is where I got some of my other Behringer stuff and the half price deal on the original Polyend Tracker, so I know that they are a reputable seller. After some consideration, the old words of Nancy Regan popped into my head, and I just said no. That was last Sunday.
I'm sure that some PHD marketing expert has determined the proper delay required before tossing a better worm in front of the fish, and today I get an email from Ebay offering me an "exclusive" $10 discount "for a limited time." I would rather have a Strymon Big Sky, but at $690, there is no F-in way! We will see what $69 gets. Paypal was sent.
I have to believe those prices are for people who dont know or have any other recourse to get the sound they want. Sometimes DIY and / or the knowledge of what's behind the panel makes things far more reasonably accessible. $69 competes well with what you can even build; almost a no brainer to me. I bet the Behringer sounds pretty good and here's to your purchase working out that way. Looking forward to hear what you think!
"Sometimes DIY and / or the knowledge of what's behind the panel makes things far more reasonably accessible."
OK, you made me curious, so I turned to Google, and asked "what's inside a Strymon Big Sky." four hundred pictures of the outsides, but no "inside the box shots" until I found something better. The big chip is an Analog Devices SHARC DSP chip. I might be able to fake my way through some Arduino code, but DSP stuff is way above my skill set.
OK, you made me curious, so I turned to Google, and asked "what's inside a Strymon Big Sky." four hundred pictures of the outsides, but no "inside the box shots" until I found something better. The big chip is an Analog Devices SHARC DSP chip. I might be able to fake my way through some Arduino code, but DSP stuff is way above my skill set.
Nuts. We own a Flint and a Blue Sky, two guitar players in the house... plus we have "real" spring reverb in 2 different amps I've built. I'm not sure who the customer is for their super MX series...seems to me it's production houses, or if one HAS to have the ability to quickly recall saved settings (assuming that is possible), or just because they can build it an some people just need it all...in practically for us it's analysis paralysis.... the smaller variants sound great, have a huge range and midi out etc and stereo and usb updatability—a shocking level of tech IMHO—I might prefer the "real" version of spring reverb... but the plate setting on the digital versions sounds best to us. Go figure. I'm certain it's all in the fingers though 
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I traced out the circuit of the VCA perf board proto that I built a few years ago. Here is a crude pencil and paper drawing. I will enter it into some sort of electronic format, wither my old version of Eagle, or LT Spice when I get time.
I'll try to fire it up in the next few days to see if it still works and try a few different tubes. This proto was wired for 6EJ7's which are sharp cutoff pentodes. If I remember correctly the control voltage range for about 70 dB of range was pretty small, maybe 5 volts. This is what I want for a music synth, but not necessarily for a compressor. The CV range can be expanded by using a remote cutoff tube like the 6EH7. The pentodes are triode wired, so lots of tubes should work by rewiring the socket.
A music synth or guitar amp doesn't frequency response out to 20 KHz, so I'm going to look for cheaper alternatives to the Edcor transformers.
On the subject of expensive blue boxes, Freeverb code does exist for SHARC, some DIY blue box work does seem to be going on. The SHARC DSP does have a little brother called Blackfin. Many years ago, I got a BF30X EVB and did get some audio through it before I managed to brick the thing. The 300 series Blackfin's are extinct, but newer parts exist. I'm not going down that rabbit hole when $30 reverb tanks exist. I do have another "secret weapon" for digital guitar FX that should be able to eat a SHARC. It runs a Ryzen 7 at 4 GHz.
I'll try to fire it up in the next few days to see if it still works and try a few different tubes. This proto was wired for 6EJ7's which are sharp cutoff pentodes. If I remember correctly the control voltage range for about 70 dB of range was pretty small, maybe 5 volts. This is what I want for a music synth, but not necessarily for a compressor. The CV range can be expanded by using a remote cutoff tube like the 6EH7. The pentodes are triode wired, so lots of tubes should work by rewiring the socket.
A music synth or guitar amp doesn't frequency response out to 20 KHz, so I'm going to look for cheaper alternatives to the Edcor transformers.
On the subject of expensive blue boxes, Freeverb code does exist for SHARC, some DIY blue box work does seem to be going on. The SHARC DSP does have a little brother called Blackfin. Many years ago, I got a BF30X EVB and did get some audio through it before I managed to brick the thing. The 300 series Blackfin's are extinct, but newer parts exist. I'm not going down that rabbit hole when $30 reverb tanks exist. I do have another "secret weapon" for digital guitar FX that should be able to eat a SHARC. It runs a Ryzen 7 at 4 GHz.
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I was thinking of Reverb as a classic side chain effect and was wondering if - in a guitar amp architecture - have a general side chain circuit as a realized concept would be beneficial. "Realized concept" being that I assume many players - these days - would easily recognize what it's for. Versus the usual "effects loop".
Basically treating the final amp stage as a mixer, where other signals can be introduced along with the main-chain of the preamp tubes / tone stack and "post" volume.
As side chain source, a low impedance drive whos input could be selected from input jack to, well anywhere along the main preamp chain. Low impedance enough to drive a reverb tank directly, if that happened to be the device plugged into the side chain circuit.
Then I took a step further into conceptual idiocy and wondered if you could mix right at the output tranny - another set of output tubes for just the side chain signal? They're current sinks and from what I remember, you can just tack 'em on down the line indefinitely and their individual signals mix. Maybe not so simple in a tube output stage, but wonder if any advantage, versus mixing "normally" at the signal level input to the power amp.
All in the realm of manufacturing cost zero concern; see what fun can be had with all this hardware we happen to have on hand. I suppose if you're really going to splurge, then have the side chain have it's own amp and speaker; mix that sound in the air.
Basically treating the final amp stage as a mixer, where other signals can be introduced along with the main-chain of the preamp tubes / tone stack and "post" volume.
As side chain source, a low impedance drive whos input could be selected from input jack to, well anywhere along the main preamp chain. Low impedance enough to drive a reverb tank directly, if that happened to be the device plugged into the side chain circuit.
Then I took a step further into conceptual idiocy and wondered if you could mix right at the output tranny - another set of output tubes for just the side chain signal? They're current sinks and from what I remember, you can just tack 'em on down the line indefinitely and their individual signals mix. Maybe not so simple in a tube output stage, but wonder if any advantage, versus mixing "normally" at the signal level input to the power amp.
All in the realm of manufacturing cost zero concern; see what fun can be had with all this hardware we happen to have on hand. I suppose if you're really going to splurge, then have the side chain have it's own amp and speaker; mix that sound in the air.
Connecting two SE amp tubes together at the OPT with each fed a different signal might work. Connecting two pair of PP outputs together at a common OPT does not go well if they are fed different signals. Neither does connecting two amps in parallel at the OPT output. Wiring them in series to a common speaker DOES work to some degree. It makes sound, but not necessarily the sound you expect. Think of wiring two guitar amps, each fed by a different guitar and player, but playing the same song, in series to a common speaker. Neither amp has any form of GNFB. All notes seem to appear in the output, but ad odd volume levels sometimes, and often with obvious IMD events, especially if one of the guitars is a bass.
Thanks for the explanation, sounds like not one of the better quadrants to pursue. I've actually thought of two players, each going into the input to a balanced modulator, like the MC1496. Which I see "Stomp Box Parts" has to sell for a whole 75c each - they used to be much more expensive, guessing they're not one of the more popular chips these days.
I suppose the two players would have to be quite disciplined in their approach to such a thing, to have anything musical as we know it, result. Perhaps they could make it - which in the hands of anyone less skilled would flop - musical regardless. The only guitar sound I recognize that uses "ring modulation" - that also made it to a large audience population - is Sabbath's "Paranoid" solo.
It all comes from - those sounds anyway - tuning around with a SW receiver as a kid. The "SSB" voice transmissions were an intriguing bit of noise you could pick up anywhere. A form of disguise, unless you had the right receiver to demod it? Also thought I read was one way to disguise a land line telephone call was to mod and demod using a local radio station audio as the carrier. With the internet, that'd get interesting, picking a carrier at random - like someone's YT 6 hour loop of a particular "Right Said Fred" song. Using delays to get it sync'd up to the carrier used in the transmission.
Anyway, if one was building a SS guitar amp with op-amps and the like, the MC1496 might be a good choice to have in the signal path. At the least, with a sine wave LFO, it could do the Tremolo. So how about a switch from the internal LFO to a 1/4" jack, where you could put any signal you want? In case your band one day covers Black Sabbath...