DIY attenuator build

[Snake5150]

Was reading you can add 500k resistors to the volume pots in a jtm 45 circuit to reduce overall volume? If this is done would a half watt resistor be large enough.

Also if the above is not possible, does anyone have a schematic for a functioning diy attenuator. If your will plz pm me the schematic and info.

[jojokeo]

Attaching a 470k resistor across a 1meg pot gives you a new pot value of 333k. The load placed on the signal is increased and the resulting output is lowered by 25% when turned up all the way. But - There's still a small bit of amplification following this mod by the CF and PI stages. This slight vol reduction will only be realized playing at very high volumes still, and will only affect the preamp drive and gain a tad. This is not nearly the same as using an attenuator. The simplest form of attenuator to build is a resistive one but will impact tone the most. You don't have to build it exactly or elaborately as the attachment shows using all of the step-downs including the line out but the most important is pay attention to the wattage values.

[Snake5150]

Attaching a 470k resistor across a 1meg pot gives you a new pot value of 333k. The load placed on the signal is increased and the resulting output is lowered by 25% when turned up all the way. But - There's still a small bit of amplification following this mod by the CF and PI stages. This slight vol reduction will only be realized playing at very high volumes still, and will only affect the preamp drive and gain a tad. This is not nearly the same as using an attenuator. The simplest form of attenuator to build is a resistive one but will impact tone the most. You don't have to build it exactly or elaborately as the attachment shows using all of the step-downs including the line out but the most important is pay attention to the wattage values.

So follow the m2 guide for the output tap I plan on using?

[Jonas]

JOJOKEO do you have a source for the inductors? maybe a part number that yielded good results?

[Latole]

Attaching a 470k resistor across a 1meg pot gives you a new pot value of 333k.

I understand he want to put resistor in series, not in parallel as you wrote.

[Snake5150]

Attaching a 470k resistor across a 1meg pot gives you a new pot value of 333k.

I understand he want to put resistor in series, not in parallel as you wrote.

I’ll prolly just build an attenuator and not do it inside the amp. From what I understand the volume reduction won’t take place till it’s almost full tilt anyways . So an off board attenuator is prolly the way to go. Unless other have more input on internal amp attenuation

[acheld]

parts-express.com is a good place to source inductors.  They're commonly used in Hi-fi crossover networks.

[pullshocks]

Parts Express is where I got the coil for the  low- watt version of the M2 that I built.  It works great. 

[Joel]

Have you read this thread?

https://el34world.com/Forum/index.php?topic=27627.msg303546#msg303546

I've since built a third M2.

[Jonas]

thank you for the links; I have not built the M2 yet but it is on the build list

[jojokeo]

For further detailed info on building this: Simple Attenuators - Design And Testing | Marshall Amp Forum

[66Strat]

Thank you for posting the schematic and the links.