Mod for Direct Outs on a Yamaha M-508 vintage mixer?

One question on this:

your thread title is 'direct out', but it has become more like an insert to the FB bus.... u have a use for that? you want the signal to go back to the FB bus or you are going to use a 'mono' jack to mute the send to the bus?

just wondering...

- michael

audiomixer said:

One question on this:

your thread title is 'direct out', but it has become more like an insert to the FB bus.... u have a use for that? you want the signal to go back to the FB bus or you are going to use a 'mono' jack to mute the send to the bus?

just wondering...

- michael

Click to expand...

Nope, when the jack is inserted it breaks the signal going back into the FB buss, but when the jack isn't inserted, the FB buss acts as normal. It's a pretty dodgy diagram haha. The signal is taken from the FB bus so the direct outputs have another form of level control, and on Mjrippes recommendation. It looks like the FB send is jumpered to be post EQ and post fader at the moment which is how I want it, so I can use the EQ and drive the pre's hard when I want to. Maybe at a later stage I'll jumper them to be post EQ and pre fader, since I've already got a form of level control but I think I'll get this sorted first!

@audiomixer - This could be easily changed to an insert by moving the wires to a point directly pre- or post-fader and changing the connections on the jack.

Update: It works! I wired up one channel tonight, and all works really well. Sounds great too! I'm using the 620ohm resistors as the build-out resistance is 600ohms as far as my reading can tell. Cheers for all the help. Next step is to do the other 7 channels...

Congratulations!  What did the output level end up being?

Ended up being surprisingly high, maybe -10? Interfaces really well with my gear regardless. Next step is drilling!

Cool.  Take your time, use a center punch and if possible a drill press.  Neatness counts 

Reviving old thread for a couple of related theory questions regarding the additions of direct outs...

The above mod operate under keeping the signal in the summing stereo buss. If a pre like this was tapped for a direct out as described (after 100ohm) to T(does it make a big difference if being driven by an op-amp or transistor?) but disconnected from the various busses, is grounding at the chassis or with the addition of 100ohm from R to S still ok?

Does the inclusion of using the FB pot to control output volume reduce the volume/ interfere with impedance matching? Whereas if I just use the signal that would have gone to pin 3 I can control the impedance the next line input sees with my buildout resistors and level control remains the volume pot?

If that 100ohm resistor wasn't there, would you need to add one for some amount of source impedance?

JohnRoberts said:

Console designers often use different active components to interface with the outside world. Further, the signal when broken out as a DO, needs to be properly referenced to ground at that output jack (typically unbalanced).

You may want to experiment with exactly where you grab signal for best result, and value of build out resistance. I would be inclined to use some R in series with low also, and send the signal 3 legged (+,-, and ground) to the DO, even though the - is just ground through a resistor.

JR

Click to expand...