RCA BA-6A Release Mod

[letterbeacon]

Hi there,

I’ve built an BA6A pretty much stock, apart from a threshold control, and I would now like to mod the release.

I suppose the easiest thing would be to add a couple more positions on the rotary switch, but would it be possible to add a pot so I can more precisely control the release?

Would it just be a case of replacing the resistor in the timing circuit with a pot? If so, which value should I start with?

Thanks a lot.

 

[emrr]

You'll need to pick the pot by ear and I recommend an end stop resistor to make a minimum value above 0Ω, unless you want 0Ω to create a GR bypass position.   

One problem you'll encounter is that it's a dual release circuit, so changing one changes the other.  If you want the longer release MORE with a faster fast release, then you'll have to change both on a complex switch. 

 

[letterbeacon]

Thanks for your reply Doug.

I only want to have the option to make the Release faster, so how about this plan:

With reference to the block diagram I've attached, I replace R11 with a 2M pot in series with a 1M resistor. This means that when the GR switch is on 'Single' I can go from approximately the stock Release at one end of the pot to a release time set by me through the travel of the pot. Would that work/ be a good place to start?

 

[emrr]

Sure, but I'd set the end stop as low as possible to taste, could be as low as 50K, I might guess 100-200K.