Hello,
I was recently researching the idea of removing my tone controls (or bypassing them) and came across this thread. In it, a member mentions 2 possibilities: 1) the tone circuit is passive, therefore replacing it with a resistor of equal value will suffice. Or, 2) Tone controls are configured as feedback networks.
I have limited knowledge in interpreting schematics, but a working knowledge in performing the repairs/mods if I clearly understand what needs to be done. If I include schematics, would any user be kind enough to tell me if my tone circuits are passive? Or if I have to research the feedback network concept a bit more before proceeding.
I'd greatly appreciate it!
I was recently researching the idea of removing my tone controls (or bypassing them) and came across this thread. In it, a member mentions 2 possibilities: 1) the tone circuit is passive, therefore replacing it with a resistor of equal value will suffice. Or, 2) Tone controls are configured as feedback networks.
I have limited knowledge in interpreting schematics, but a working knowledge in performing the repairs/mods if I clearly understand what needs to be done. If I include schematics, would any user be kind enough to tell me if my tone circuits are passive? Or if I have to research the feedback network concept a bit more before proceeding.
I'd greatly appreciate it!
Apologies for the double post, but I came across this in the Amplifier Block II section of the service manual:
Stating the Volume is 500k and the Tone Control is 50k. Does this prove they're passive? Ideally I'd also like to remove the volume knobs as well, but hopefully this helps.
EDIT:
Upon further inspection of the schematic, I think I've located the components.
Stating the Volume is 500k and the Tone Control is 50k. Does this prove they're passive? Ideally I'd also like to remove the volume knobs as well, but hopefully this helps.
EDIT:
Upon further inspection of the schematic, I think I've located the components.
Last edited:
To remove the treble cut or tone, lift out C08, both channels.
To remove the volume as well, (why anyone wants to have everything at full distorted volume is a mystery), remove both tone and volume controls, connect a 0.1 (100nF) capacitor between point O and pin 2 of V1, like wise do the same on the other channel (pin 7 of V1).
Connect a 470k 1/4W resistor between pin 2 of V1 to ground and pin 7 of V1 to ground.
You will now have uncontollable record levels and playback levels!
Yes the controls are passive, as is the NAB equaliser on the pre amp stage.
To remove the volume as well, (why anyone wants to have everything at full distorted volume is a mystery), remove both tone and volume controls, connect a 0.1 (100nF) capacitor between point O and pin 2 of V1, like wise do the same on the other channel (pin 7 of V1).
Connect a 470k 1/4W resistor between pin 2 of V1 to ground and pin 7 of V1 to ground.
You will now have uncontollable record levels and playback levels!
Yes the controls are passive, as is the NAB equaliser on the pre amp stage.
Thank you so much!!! Just to fully understand, I'm simply removing c08 from the equation entirely, and not replacing it with anything? On both channels of course.
To clarify with the volume discrepancy, I'm controlling the volume being sent to the machine from my audio interface, as well as the return levels. I may opt to keep the volume knobs, but I wanted to eliminate the possibility of volumes differences between L+R. This machine is mainly used to bounce audio from digital to tape and back to digital again, haha.
I really appreciate your insight-- it's a HUGE help!
I see. Thank you for bringing that up. The level meters are essential for my uses.
Does the image in this post help at all? Replacing these pots with equal value resistors, would that accomplish a tone control bypass?
I wouldn't even do that. Just disconnect the output lead from the centre terminal of each pot and reconnect to the top terminal as per schematic.