Requesting input on correctly trimming this circuit down to size...

[brad]

My current project is rehousing and readapting an old digital multi-effect for modern use, and part of this will involve redesigning the analog in/out daughterboard so it fits in my enclosure properly.  Non-essential features will be ditched to save space, and I'd also like to replace the 12v AC power section with one that runs off a 1A 12v DC wall-wart.  I'd really love some input on a couple of issues before I design the trimmed down version though...



Issue 1:
I'm going to leave off a few of the jacks, but I'm not sure what I should do with their corresponding wires on the header connection.  After looking at the schematic, am I correct in assuming that:
* The "manual" and "bypass" jacks are normally grounded -so I should ground their empty header pins to the chassis.
* The "exp. pedal" and "phones" jacks are normally open -so I can leave their header pins open.
* The "Output R" jack is ...normally grounded to AGND via the 'mute' transistor?  I'm not sure about this one 

Issue 2:
Do I need to include the two EMF filters shown on the AC input if I'm going to replace it with a DC supply?  I was planning on just having filter caps on the DC input, and then use 7805 and 7808 voltage regulators to break it down for the +5v and +8v.  Are those EMF filters required because it powers a digital device?

Issue 3:
There are 3 types of ground shown in the schematic.  Does this mean I should keep all the digital grounds and analog grounds on separate tracks, and then ground them to the points labeled "A,D" at the powersupply?

Thanks in advance for any suggestions.  This project is making me lose sleep! 

[Sir H C]

issue 1:

You are right on the first ones.  For the mute transistor, if you don't care to be able to mute, let the bases be tied to ground only, if you want to mute, then you need that connection so a positive voltage on the mute will shut the outputs off.

issue 2:

Those EMF filters are probably to keep the digital noise off the AC and keep AC noise off the effects.  Don't need if powering from DC.

Issue 3:

Yes, the idea is to keep the digital noise away from the analog signals until you are at the power supply.  Yes those traces are low resistance, but you have some sensitive analog signals and 50mV of noise can kill things.

[brad]

Awesome!  Thanks for that 

So if I want to ditch the entire right output, will I just leave the "OUT R" pin on the header open?

Also, the original power adapter is a 600ma 12v AC wall wart ...so using a 1A 12v DC wall wart with 7805 and 7808 voltage regulators should be an adequate substitute?

I'm really looking forward to seeing if this new version has less noise, since all those obsolete semis will be replaced by modern versions.

[brad]

Here's my redesigned schematic...



Are there any problems with my new DC power supply design?

[Sir H C]

Looks good to me.