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The Solo series has evolved from the simple v4, to a more capable v5, and the synth-inspired v6 amplifiers. In many ways, each version built upon the prior generations. The v7 is a genuine break from prior Solo generations. Its novelty begins with a unique modular design and construction approach, and extends to its user controls and virtually all circuit functions.
The Solo series has evolved from the simple v4, to a more capable v5, and the synth-inspired v6 amplifiers. In many ways, each version built upon the prior generations. The v7 is a genuine break from prior Solo generations. Its novelty begins with a unique modular design and construction approach, and extends to its user controls and virtually all circuit functions.
The v7 is simply new and unique so there is nothing like it anywhere. It begins with the idea that customization should be possible without redesigning or rebuilding the entire amplifier. Two independent channels are provided for flexibility, and each channel can be configured and controlled from the front panel and foot-switches. Effects like overdrive and tremolo and reverb are available to either or both channels.
The v7 is simply new and unique so there is nothing like it anywhere. It begins with the idea that customization should be possible without redesigning or rebuilding the entire amplifier. Two independent channels are provided for flexibility, and each channel can be configured and controlled from the front panel and foot-switches. Effects like overdrive and tremolo and reverb are available to either or both channels.
The first v7 module is the power amp. It is an extension of the original AOT concept. It’s still a bridged solid state output stage generating ~60 watts RMS into 8 ohms. However, v7 includes output impedance and presence controls. Output impedance control was the primary motivation for this design. Tube and SS amplifiers differ drastically in their output impedance. Tube amplifiers have relatively higher output impedance, compared to solid state designs. Much has been claimed and written about that difference. IMO it boils down to a few points.
The first v7 module is the power amp. It is an extension of the original AOT concept. It’s still a bridged solid state output stage generating ~60 watts RMS into 8 ohms. However, v7 includes output impedance and presence controls. Output impedance control was the primary motivation for this design. Tube and SS amplifiers differ drastically in their output impedance. Tube amplifiers have relatively higher output impedance, compared to solid state designs. Much has been claimed and written about that difference. IMO it boils down to a few points.
1) High output impedance (20-200 ohms) is common with tube power amplifiers. SS amplifiers have low output impedance, often less than 1 ohm.
1) High output impedance (20-200 ohms) is common with tube power amplifiers. SS amplifiers have low output impedance, often less than 1 ohm.
2) Output impedance impacts a speaker’s freedom to resonate and produce its innate tone quality. Higher output impedance allows a speaker to contribute more to the tone. Lower output impedance constrains a speaker to reproduce the amplifier signal exactly.
2) Output impedance impacts a speaker’s freedom to resonate and produce its innate tone quality. Higher output impedance allows a speaker to contribute more to the tone. Lower output impedance constrains a speaker to reproduce the amplifier signal exactly.
3) Speaker impedance varies with frequency, typically increasing in the bass and high freq’s, with dips in mid freq’s. These variations are distinctive for a given speaker.
3) Speaker impedance varies with frequency, typically increasing in the bass and high freq’s, with dips in mid freq’s. These variations are distinctive for a given speaker.
4) A low output impedance forces a speaker to reproduce the amplifier signal, regardless of a speaker’s impedance variations. So, speaker variations are suppressed with low output impedance. While this is generally desirable for hi-fi, it matters less for guitars.
4) A low output impedance forces a speaker to reproduce the amplifier signal, regardless of a speaker’s impedance variations. So, speaker variations are suppressed with low output impedance. While this is generally desirable for hi-fi, it matters less for guitars.
5) With a high output impedance amplifier, a speaker’s unique impedance curve shapes the tone. Higher speaker impedance increases speaker power, so the power delivered to the speaker varies with speaker impedance, which is a function of frequency.
5) With a high output impedance amplifier, a speaker’s unique impedance curve shapes the tone. Higher speaker impedance increases speaker power, so the power delivered to the speaker varies with speaker impedance, which is a function of frequency.
The original AOT design has a low output impedance, roughly ½ ohm according to simulations, making speaker impedance variations relatively unimportant. Therefore, speakers sound similar, which is both good and bad. Speaker choice is not as important, and speaker variations are minimized.
The original AOT design has a low output impedance, roughly ½ ohm according to simulations, making speaker impedance variations relatively unimportant. Therefore, speakers sound similar, which is both good and bad. Speaker choice is not as important, and speaker variations are minimized.
The speaker industry puts a lot of effort into creating speakers for tube amps where speaker impedance variations matter. A goal of v7 is to capture those variations in a controlled fashion.
The speaker industry puts a lot of effort into creating speakers for tube amps where speaker impedance variations matter. A goal of v7 is to capture those variations in a controlled fashion.
v7 incorporates a variable output impedance control, called resonance. It controls how much a speaker’s resonance and impedance curve impacts tone. Technically, it varies the output impedance from 200 ohms to essentially zero. At the zero position (low resonance), the v7 stage behaves like a prior AOT stage. Speaker variations are minimized and the tone is consistent and mainly shaped by the amplifier signal. In the higher resonance positions, a speaker’s unique impedance curve and mechanical resonances impact the tone. Mid positions of the control allow a mix of the two extremes.
v7 incorporates a variable output impedance control, called resonance. It controls how much a speaker’s resonance and impedance curve impacts tone. Technically, it varies the output impedance from 200 ohms to essentially zero. At the zero position (low resonance), the v7 stage behaves like a prior AOT stage. Speaker variations are minimized and the tone is consistent and mainly shaped by the amplifier signal. In the higher resonance positions, a speaker’s unique impedance curve and mechanical resonances impact the tone. Mid positions of the control allow a mix of the two extremes.
In addition to the resonance control, a presence control increases the high frequency output impedance and response (typically peaked at 4-5 KHz), like many tube amps with similar presence controls.
In addition to the resonance control, a presence control increases the high frequency output impedance and response (typically peaked at 4-5 KHz), like many tube amps with similar presence controls.
Play testing confirms the expected effects. Speakers matter with high resonance. The ability to control output impedance is useful and adds variations for each speaker tested. High resonance is distinctly more “tubey” sounding, as expected.
Play testing confirms the expected effects. Speakers matter with high resonance. The ability to control output impedance is useful and adds variations for each speaker tested. High resonance is distinctly more “tubey” sounding, as expected.
The second v7 module is the preamp, and it builds on classic tube stages and passive tone controls. The preamp uses 4 triodes (two tubes) in two configurations based on the Bassman (BM) and Deluxe Reverb (DR) amplifiers. These signal paths are the basis for dozens of amplifiers with only minor component variations. The v7 preamp can be customized to replicate many of them. The default configurations are the 5F6A and AB763 amplifiers. Each channel has independent volume and BMT tone controls and one-button switching to select between them.
The second v7 module is the preamp, and it builds on classic tube stages and passive tone controls. The preamp uses 4 triodes (two tubes) in two configurations based on the Bassman (BM) and Deluxe Reverb (DR) amplifiers. These signal paths are the basis for dozens of amplifiers with only minor component variations. The v7 preamp can be customized to replicate many of them. The default configurations are the 5F6A and AB763 amplifiers. Each channel has independent volume and BMT tone controls and one-button switching to select between them.
The preamp module performs all the signal path switching based on front panel or foot-switch controls. A signal path is set with front panel push-buttons, and colored LEDS indicate the current setting for option. Foot-switches have a dedicated channel select button and additional buttons that can be user-assigned to functions. The front panel LEDs always show the current state of the signal path. All path settings are saved so the amplifier always powers up to the same settings last used.
The preamp module performs all the signal path switching based on front panel or foot-switch controls. A signal path is set with front panel push-buttons, and colored LEDS indicate the current setting for option. Foot-switches have a dedicated channel select button and additional buttons that can be user-assigned to functions. The front panel LEDs always show the current state of the signal path. All path settings are saved so the amplifier always powers up to the same settings last used.
Effects may be introduced (or not) into a channel’s signal paths. One effect is inserted between the input jack and the first tube stage. This is currently an overdrive effect (OD1). A second effect may be inserted after the first tube stage. This is currently a second overdrive (OD2). The effects are implemented as physically-separate boards from the preamp, so they may be modified or customized without impacting the preamp board or its circuits. OD1 and OD2 are based on tube screamer designs. OD1 behaves essentially like an external pedal, but since it’s built in, there are no power cords or cables to fuss with, and switching is controlled by the amplifier. OD2 is unique since it operates after the 1st tube stage where signal levels are higher and noise is lower. OD2 is also voiced for a smoother tone to compliment OD1. Either or both, OD1 and OD2, can be enabled to provide a channel with massive gain and tone flexibility.
Effects may be introduced (or not) into a channel’s signal paths. One effect is inserted between the input jack and the first tube stage. This is currently an overdrive effect (OD1). A second effect may be inserted after the first tube stage. This is currently a second overdrive (OD2). The effects are implemented as physically-separate boards from the preamp, so they may be modified or customized without impacting the preamp board or its circuits. OD1 and OD2 are based on tube screamer designs. OD1 behaves essentially like an external pedal, but since it’s built in, there are no power cords or cables to fuss with, and switching is controlled by the amplifier. OD2 is unique since it operates after the 1st tube stage where signal levels are higher and noise is lower. OD2 is also voiced for a smoother tone to compliment OD1. Either or both, OD1 and OD2, can be enabled to provide a channel with massive gain and tone flexibility.
A third effect is inserted after all the preamp channel circuitry and an external effects loop. The default is a combination of Reverb and Tremolo. Reverb is digital, with variable decay and amplitude. Tremolo effects offer amplitude or harmonic modulation. Each channel can set different reverb decay and tremolo modulations. These effects are also physically separate from the preamp, so they may be modified or customized without impacting the preamp board or circuits.
A third effect is inserted after all the preamp channel circuitry and an external effects loop. The default is a combination of Reverb and Tremolo. Reverb is digital, with variable decay and amplitude. Tremolo effects offer amplitude or harmonic modulation. Each channel can set different reverb decay and tremolo modulations. These effects are also physically separate from the preamp, so they may be modified or customized without impacting the preamp board or circuits.
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