thunderaxe
Member
hi all,
i'm in the process of designing a phaser with switchable stages and from most of the circuit designs i've seen it seems like people generally try to avoid feedback for 2-stage phasers -- the MXR phase 95 and pedalPCB XC phase just put the feedback control after the 2/4 stage switch so that it's only in the 4-stage path, and another thread i read about building a phaser circuit starting with 2 stages and then expanding to 4 and 6 said, "now that we have 4 stages we can add a feedback control"
which makes me wonder why -- is it just not useful in 2 stages? does it not work? does it cause problems?
one possible answer i've come across was a comment from mark hammer saying that for different phase reasons it's best to send feedback to odd numbered stages, which is how the phase 90/95 does it. but my two favourite phaser circuits, the boss PH-1R and mu-tron phasor ii, send it back to the beginning of the circuit, which would be 4 and 6 stages respectively, but also before the input buffer op amp, so while it's 4 and 6 phase stages, it's 5 and 7 op amp stages each. does this solve whatever problems there might otherwise be with feedback in 2-stage phasers specifically, or even numbers of phase stages more generally?
thanks!!
i'm in the process of designing a phaser with switchable stages and from most of the circuit designs i've seen it seems like people generally try to avoid feedback for 2-stage phasers -- the MXR phase 95 and pedalPCB XC phase just put the feedback control after the 2/4 stage switch so that it's only in the 4-stage path, and another thread i read about building a phaser circuit starting with 2 stages and then expanding to 4 and 6 said, "now that we have 4 stages we can add a feedback control"
which makes me wonder why -- is it just not useful in 2 stages? does it not work? does it cause problems?
one possible answer i've come across was a comment from mark hammer saying that for different phase reasons it's best to send feedback to odd numbered stages, which is how the phase 90/95 does it. but my two favourite phaser circuits, the boss PH-1R and mu-tron phasor ii, send it back to the beginning of the circuit, which would be 4 and 6 stages respectively, but also before the input buffer op amp, so while it's 4 and 6 phase stages, it's 5 and 7 op amp stages each. does this solve whatever problems there might otherwise be with feedback in 2-stage phasers specifically, or even numbers of phase stages more generally?
thanks!!
