Modify for EQ on/off switch – Alice 828 MK1

[WHoops]

Hello Ted,

how are you? Wish you well

I have an Alice 828 MK1 and would like to modify it  so that I would be able to have a switch to turn the EQ on/off like in the MK2, stock the MK1 has the EQ always on the channels.

Is it possible to modify the MK1 to have an On/off switch on the EQ? if so where do you advise on the schematic to cut the connections for the switch

Thank you so much

T

 

[Ted Fletcher]

It would be possible to add an EQ in/out switch, but there may be problems with levels.
The top of the channel fader is fed by a 100uF cap. Switching the input of that from the output of the input amplifier should do the job, but I would advise against it because of probably unforseen level and stability problems.
If anyone asks me to carry out that mod, the answer would be no!

[Ted Fletcher]

Here is the circuit diagram.

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[ilcaccillo]

Hi Ted,

I also own a 828 MK1 mixer, and I would love to have an useful ON/OFF switch for the EQ section like Whoops asked.

I can see that in your new 828 mixer the MK3 that is based on the MK1 circuitry , you included a really useful ON/OFF switch for the EQ section.

Although you advised in the past of not performing this mod on an MK1, you probably found a clever way of including the ON/OFF switch without incurring into the “Level and Stability” problems you mentioned before.

I would like to ask you if you please could help me out on how could I modify my MK1 to include an On/OFF switch in the EQ as it’s implemented on the MK3 mixer?

Thank you so much for your work Ted and for all your Kind help

Best Regards

[ilcaccillo]

Hello Ted,

How are you?

Any chance you had some time to read my last reply?

Thank you so much

My best regards

[Ted Fletcher]

Hi Ilcaccillo,
There’s a lot going on!
The way I changed the circuitry on the Mk3 828 to include an on/off switch was by adding a further buffer stage immeiately before the channel fader, this made the mod possible but it’s not really a practical proposition on an existing Mk1 mixer, bearing in mind that the mixer is now very old and the mod requires a great deal of work.

[ilcaccillo]

Hello Ted,

thank you so much for your kind reply

 

[ilcaccillo]

Hi Ted,

I would love to try that mod out on my MK1 mixer, at least try that in one channel and see out it goes, I really feel the need to have a switchable EQ in and out.

Any chance you could share the circuit of the buffer stage you implemented and help me out perform that mod in one channel?

 

Thank you so much

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