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01-04-2021, 04:01 AM
Hi Kevin,
Thanks for explaining this.
I have scanned the complete Albion schematic and attached it for your reference.
Is this a normal level of gain for this type of circuit and if so, why would you want that much signal slamming the grid of the next stage?
I had considered that removing C3 may cut the gain a fair bit, but it is a radial electro and is glued to the PCB; too much trouble to remove.
The Input Stage is stock and I am surprised they didn't just use a normal 12AX7 stage.
I was concerned about resistor noise with the high series R and I intended reducing R and shunting the Gain pot, once I found a suitable divider ratio, but there is no perceptible noise, so I left it as is.
The out of phase channels don't pose any problems and the channel switching removes the non operating channel - without any bleed through.
R82 was also 100k and I changed it to 10k because it allowed too much OD, even with Drive at 0.
Grid Stops were a worry to me also, but surprisingly, there was no indication of any problems, but I added the 330k stopper to V2B to cut some Treble and add a bit of insurance. I may add some stoppers, to the stages that have none, as a safeguard.
The Source Follower driving the Tone Stack is stock, as is all of the A channel; apart from R8, which I changed to 3k9, because we preferred the tone.
Would it be wise to increase R15?
With the effective load of 175k on V2B, I figured a gain of 21 and I measure an actual gain of less than 12. What do you think?
I am not fussed on Bright Caps on pots either and I may remove C61, although I haven't noticed any undesirable effects from it. Maybe the series 470k negates a lot of the treble bleed?
The A channel does have a good OD, but it is used purely as a Clean channel only. VR1 & VR2 provide useful tone variations; I like controls.
Thanks again for all your help and we are having fun, despite the pandemic.
Cheers, Noel.
Albion TCT35 HG iss3 circuit diagram.pdf (Size: 243.16 KB / Downloads: 30)
Thanks for explaining this.
I have scanned the complete Albion schematic and attached it for your reference.
Is this a normal level of gain for this type of circuit and if so, why would you want that much signal slamming the grid of the next stage?
I had considered that removing C3 may cut the gain a fair bit, but it is a radial electro and is glued to the PCB; too much trouble to remove.
The Input Stage is stock and I am surprised they didn't just use a normal 12AX7 stage.
I was concerned about resistor noise with the high series R and I intended reducing R and shunting the Gain pot, once I found a suitable divider ratio, but there is no perceptible noise, so I left it as is.
The out of phase channels don't pose any problems and the channel switching removes the non operating channel - without any bleed through.
R82 was also 100k and I changed it to 10k because it allowed too much OD, even with Drive at 0.
Grid Stops were a worry to me also, but surprisingly, there was no indication of any problems, but I added the 330k stopper to V2B to cut some Treble and add a bit of insurance. I may add some stoppers, to the stages that have none, as a safeguard.
The Source Follower driving the Tone Stack is stock, as is all of the A channel; apart from R8, which I changed to 3k9, because we preferred the tone.
Would it be wise to increase R15?
With the effective load of 175k on V2B, I figured a gain of 21 and I measure an actual gain of less than 12. What do you think?
I am not fussed on Bright Caps on pots either and I may remove C61, although I haven't noticed any undesirable effects from it. Maybe the series 470k negates a lot of the treble bleed?
The A channel does have a good OD, but it is used purely as a Clean channel only. VR1 & VR2 provide useful tone variations; I like controls.
Thanks again for all your help and we are having fun, despite the pandemic.
Cheers, Noel.
Albion TCT35 HG iss3 circuit diagram.pdf (Size: 243.16 KB / Downloads: 30)
