I have been researching the past couple of weeks trying to design my first amp, including adding some of my own ideas and taking from other amps. I have been trying to make an amp that has just about every feature in the book that most of us would want in an amp with the type of tone that we all enjoy while dealing with the flaws that have been apparent in a few of the favs.
I am trying to pick up a consensus regarding mostly two amps, the beloved 5150 and 2ch Dual Rectifier. My first main tackle with the 5150 is how it can be very fizzy, even when given a bias mod and biased a lot warmer (way out of crossover). I thought It could be many things along the preamp including the expressibly warm bias of the preamp tubes minus the Soldano stage.
However looking at both the 2ch recto schems and SLO 100, all three amps are nearly identical as far as the preamps are concerned (they have different ways of achieving the same and a few different values are only off by a tiny amount). The big thing I noticed was the differences in the Global Feedback, which is where the three amps really differ drastically (not that drastic but the most drastic difference). Having more feedback, the 5150 gains the ability to have more low end because with the resonance knob the signal above 400Hz (as specified in Peavey's Patent) will be attenuated much more than the low frequencies. Higher amounts of feedback also add more bandwidth making the amp more linear and "Solid State" like which would account for a lot of the fizz.
So that leads me the the MAIN question. For those that have had good amounts of time on a 5150 MkI, 2Ch. Dual Recto, and SLO 100, how much do these amps really vary in terms of characteristics? Mainly fizz and other characteristics in the high end. I know the 5150s have much more upper mid grind but have a softer high end (which some people don't like) where the other amps tend to be more cutting in the highs and softer in the mids.
The other question that I have is if anyone has excessive feedback when any three amps are cranked up. I noticed that my 5150 has excessive amount of microphonics on the first stage of V1 regardless of what tube is in that slot. I noticed that in all three schematics, the gain for the first gain stages are quite high and plan on having a much lower gain.
I will continue to ask questions as new things develop.
The concept of the amp and all of its many features where things that I wanted in an amp and deal with flaws in other amps as well of things I have heard other people mention they wished where featured in an amp. Just a bit about the amp so far:
-Built-in Germanium Diode 808-based Tube Screamer with assymetrical/symmetrical modes (footswitchable) with true bypass
-3 Channels (1 clean 2 high gain). High gain has 2 Modes each with independent tone stack and feedback controls (each tone stack can be bypassed to use an external tonestack)
-Separate High Gain and Clean preamp
-Each High Gain Mode has Independent preamp bias adjustment on the SLO stage for better lower gain non metal tones
-American and British voiced channels with each mode of both channels having its independent mid sweep and preamp bias switch
-High Gain has two gain controls like the Engl Savage and Fryette Sig:X that are accumulative in the lead mode (Gain I for the Rhythm Mode, Gain I and Gain II for the Lead Mode)
-High Gain based off SLO/5150
-Clean Channel based of 65 Twin Reverb Normal Channel
-Serial/Parallel FX loop (footswitchable)
-Second Series FX loop before the main FX loop with gain adjustment for using external tone stacks (if this is implemented the tone stack bypass will be footswitchable as well)
-Footswitchable solo boost (up to +20db)
-Stereo/Mono FX return
-External Tonestack and Global Feedback
-Power Amp line out (for recording direct)
-4 12AX7, 1 12DW7, 2 12AT7
-Any choice of Tubes, 6L6s or KT88s will come standard
-Stereo/Mono Power amp; x2 50W Stereo Power amps with footswitchable Stereo and Bridged Mono mode.
-Adjustable Selectable Voltage regulator to simulate Mesa Boogies Bold/Spongy Mains Reduction/Lower watt modes and achieve power tube saturation at lower levels
-Adjustable Primary Impedance of the output transformer coupled with variable voltage regulators to properly setup any octal power tubes from EL34s to KT88s
-Adjustable external bias with test points
-Shunted Load on the speaker outs (won't ruin the amp if a cabinet is not plugged in but is still not safe to play without a proper load)
-And best of all, ALL FOOTSWITCHING IS MIDI CONTROLLED!!! The amps will actually come with midi footswitches designed specifically for a cheap solution for each particular model.
-Full programmable Midi footswitching system, Rackmount amp switchers, FX loopers including a stereo/mono looper for the stereo return FX
Any ideas or advice is always welcome.
EDIT June 8: So I took out the idea of a preamp out, no real use for it considering the poweramp out and made adjustments to the power section's mono/stereo control, which would bring down the price a lot. I also removed the possible idea of having a reactive load attenuator as with the Variable voltage regulator, power tube saturation can be had at bedroom volumes so there is no point. There will now also be a serial FX loop that bypasses the tonestack that allows for external tone stacks at the same time there will be a bypassable global feedback output which will allow for external feedback controls as well (this would allow for an entire rackmount external tonestack and feedback controls).
I have the schematics for the preamps and power amp section. The only thing left to do is to get the tonestack and FX loop design down on the high gain part of the amp and interface it with the power section.
I am trying to pick up a consensus regarding mostly two amps, the beloved 5150 and 2ch Dual Rectifier. My first main tackle with the 5150 is how it can be very fizzy, even when given a bias mod and biased a lot warmer (way out of crossover). I thought It could be many things along the preamp including the expressibly warm bias of the preamp tubes minus the Soldano stage.
However looking at both the 2ch recto schems and SLO 100, all three amps are nearly identical as far as the preamps are concerned (they have different ways of achieving the same and a few different values are only off by a tiny amount). The big thing I noticed was the differences in the Global Feedback, which is where the three amps really differ drastically (not that drastic but the most drastic difference). Having more feedback, the 5150 gains the ability to have more low end because with the resonance knob the signal above 400Hz (as specified in Peavey's Patent) will be attenuated much more than the low frequencies. Higher amounts of feedback also add more bandwidth making the amp more linear and "Solid State" like which would account for a lot of the fizz.
So that leads me the the MAIN question. For those that have had good amounts of time on a 5150 MkI, 2Ch. Dual Recto, and SLO 100, how much do these amps really vary in terms of characteristics? Mainly fizz and other characteristics in the high end. I know the 5150s have much more upper mid grind but have a softer high end (which some people don't like) where the other amps tend to be more cutting in the highs and softer in the mids.
The other question that I have is if anyone has excessive feedback when any three amps are cranked up. I noticed that my 5150 has excessive amount of microphonics on the first stage of V1 regardless of what tube is in that slot. I noticed that in all three schematics, the gain for the first gain stages are quite high and plan on having a much lower gain.
I will continue to ask questions as new things develop.
The concept of the amp and all of its many features where things that I wanted in an amp and deal with flaws in other amps as well of things I have heard other people mention they wished where featured in an amp. Just a bit about the amp so far:
-Built-in Germanium Diode 808-based Tube Screamer with assymetrical/symmetrical modes (footswitchable) with true bypass
-3 Channels (1 clean 2 high gain). High gain has 2 Modes each with independent tone stack and feedback controls (each tone stack can be bypassed to use an external tonestack)
-Separate High Gain and Clean preamp
-Each High Gain Mode has Independent preamp bias adjustment on the SLO stage for better lower gain non metal tones
-American and British voiced channels with each mode of both channels having its independent mid sweep and preamp bias switch
-High Gain has two gain controls like the Engl Savage and Fryette Sig:X that are accumulative in the lead mode (Gain I for the Rhythm Mode, Gain I and Gain II for the Lead Mode)
-High Gain based off SLO/5150
-Clean Channel based of 65 Twin Reverb Normal Channel
-Serial/Parallel FX loop (footswitchable)
-Second Series FX loop before the main FX loop with gain adjustment for using external tone stacks (if this is implemented the tone stack bypass will be footswitchable as well)
-Footswitchable solo boost (up to +20db)
-Stereo/Mono FX return
-External Tonestack and Global Feedback
-Power Amp line out (for recording direct)
-4 12AX7, 1 12DW7, 2 12AT7
-Any choice of Tubes, 6L6s or KT88s will come standard
-Stereo/Mono Power amp; x2 50W Stereo Power amps with footswitchable Stereo and Bridged Mono mode.
-Adjustable Selectable Voltage regulator to simulate Mesa Boogies Bold/Spongy Mains Reduction/Lower watt modes and achieve power tube saturation at lower levels
-Adjustable Primary Impedance of the output transformer coupled with variable voltage regulators to properly setup any octal power tubes from EL34s to KT88s
-Adjustable external bias with test points
-Shunted Load on the speaker outs (won't ruin the amp if a cabinet is not plugged in but is still not safe to play without a proper load)
-And best of all, ALL FOOTSWITCHING IS MIDI CONTROLLED!!! The amps will actually come with midi footswitches designed specifically for a cheap solution for each particular model.
-Full programmable Midi footswitching system, Rackmount amp switchers, FX loopers including a stereo/mono looper for the stereo return FX
Any ideas or advice is always welcome.
EDIT June 8: So I took out the idea of a preamp out, no real use for it considering the poweramp out and made adjustments to the power section's mono/stereo control, which would bring down the price a lot. I also removed the possible idea of having a reactive load attenuator as with the Variable voltage regulator, power tube saturation can be had at bedroom volumes so there is no point. There will now also be a serial FX loop that bypasses the tonestack that allows for external tone stacks at the same time there will be a bypassable global feedback output which will allow for external feedback controls as well (this would allow for an entire rackmount external tonestack and feedback controls).
I have the schematics for the preamps and power amp section. The only thing left to do is to get the tonestack and FX loop design down on the high gain part of the amp and interface it with the power section.
