Stereomour - guide for switchable line-out to Crack

[Horatio]

As part of my recently completed Steromour build I decided to add a switchable line out to connect it to my Crack. This allows me to leave both my Steromour and Crack switched on, switching between speakers and headphones using an additional selector switch I added to the Steromour. When I turn the switch it redirects the line-in audio to a pair of output RCA jacks that I have connected to the Crack while simultaneously cutting the line-in connection to the volume pot silencing the Steromour and speakers.

Here is how I did it... Use at your own risk...

1) I sent a nice email to the very helpful Bottlehead team and ordered an additional selector switch, 2 x RCA jacks and 1m of STP cable when I placed my Stereomour order. Aftermarket parts would have been fine...

2) Drill a 10mm hole directly beneath each of the two sets of speaker mounts. The supplied face plate is easy to drill through - just buy a metal drill bit. TIP: Screw the faceplate to a block of wood to hold it tight while you drill.

3) Drill a 10mm hole directly between the two existing holes at the front of the faceplate - exactly in the middle of the existing selector switch and volume pot holes. Use a Dremmel or a small file to shave the side slot so that it exactly matches the other two holes on the faceplate.

3) Fit the 2 RCA jack connectors into the two holes you drilled beneath the speaker mounts.

4) Take the additional selector switch and remove the nut and washer around the centre pole. Move the locking tab so that the selector only has 2 positions it can turn to.

5) Fit the additional selector switch to the hole you made between the original selector switch and volume pot.

6) Wire the original original selector switch to the input RCA jacks as normal.

7) Wire each of the 4 centre pins of the original selector switch to the equivalent centre pin on the new switch you added using STP wire - I cut the drain wire at each end.

8 ) Wire the new selector switch to the volume pot as follows:

New Selector Switch Pin 2 connect Red STP to Volume pot lower pin closest to the selector switch
New Selector Switch Pin 5 connect Black STP to Volume pot lower pin furthest away from the selector switch
Drain wire remove at selector switch end, attach to terminal 8 lower at volume pot end

New Selector Switch Pin 11 connect Red STP to Volume pot top pin closest to the selector switch
New Selector Switch Pin 8 connect Black STP to Volume pot top pin furthest away from the selector switch
Drain wire remove at selector switch end, attach to terminal 8 lower at volume pot end

9) Wire the new selector switch to the two new line-out RCA jacks you added below the speaker mounts as follows:

New Selector Switch Pin 1 Red STP to New RCA Right centre pin
New Selector Switch Pin 4 Black STP to New RCA Right ground tab
Drain wire remove at RCA end, attach to terminal 13 lower at selector switch end

New Selector Switch Pin 10 Red STP to New RCA Left centre pin
New Selector Switch Pin 7 Black STP to New RCA Left ground tab
Drain wire remove at RCA end, attach to terminal 13 lower at selector switch end

10) Connect your Crack to the extra phono’s you added and use the new selector switch to select Crack or Speaker output

[borism]

This is a great guide for a switchable line out to Crack!

If you don't need all 3 RCA inputs (I am only using 2) you can also wire one pair of the existing RCAs to the out of the 3-position switch. The only issue is that when listening through the Crack the speakers will not be turned off but this can be accomplished by turning down the volume or even turning off the Stereomour.

[denti alligator]

I wonder how hard this would be to do with the new a Stereomour.

[Paul Birkeland]

I wonder how hard this would be to do with the new a Stereomour.

You can do roughly the same thing with the Stereomour II, though beware that the attenuator upgrade will not install properly with the extra switch up front.

An easier solution is to wire the output of the selector switch back to another pair of jacks at the back.  If you haven't build your Stereomour II yet, there's actually enough wire in the second selector switch to RCA cable to add this pretty easily.  If you want to listen to your Crack and not your Stereomour, then you'd just turn your Stereomour off, or turn the volume control all the way down.

[denti alligator]

You can do roughly the same thing with the Stereomour II, though beware that the attenuator upgrade will not install properly with the extra switch up front.

An easier solution is to wire the output of the selector switch back to another pair of jacks at the back.  If you haven't build your Stereomour II yet, there's actually enough wire in the second selector switch to RCA cable to add this pretty easily.  If you want to listen to your Crack and not your Stereomour, then you'd just turn your Stereomour off, or turn the volume control all the way down.

I'm seriously considering the Stereomour II as a next kit, and wouldn't want to mess with the upgradability. So I could use the selector switch on the Stereomour and listen through (and control volume on) the Crack or SEX, if it were connected to another set of output jacks? Are you saying I wouldn't need a selector switch for the outputs in this case?

[Paul Birkeland]

I'm seriously considering the Stereomour II as a next kit, and wouldn't want to mess with the upgradability. So I could use the selector switch on the Stereomour and listen through (and control volume on) the Crack or SEX, if it were connected to another set of output jacks? Are you saying I wouldn't need a selector switch for the outputs in this case?

Yeah, you just send the output of the selector back to the set of RCA jacks you've added.

[denti alligator]

Yeah, you just send the output of the selector back to the set of RCA jacks you've added.

Very cool, thanks. So when I order could I ask for an additional pair of RCAs? Then I'd be set to go.

By the way, are the planned upgrades to the Stereomour II going to be similar to those available for the Smash?

[denti alligator]

Would it be possible to add TWO pairs of extra RCA outs to connect TWO headphone amps and listen to them simultaneously? The trouble would be finding a place to put the jacks, I guess.

[Paul Birkeland]

I would just use a pair of splitters on one pair of jacks.  At a certain point, there just isn't going to be enough room on the chassis to cram on more connectors.

-PB

[denti alligator]

OK, Stereomour II ordered!!

I think I have an extra pair of RCA jacks. Assuming I put these near the speaker lugs in the back, would there still be enough wire left over to run from the selector switch to these extra RCAs? Does it matter where I run the wires?

[Paul Birkeland]

There's actually an unused pair of twisted pairs available in the Stereomour that could be used just for this purpose.  In the instructions, when it is written to trim off two of the twisted pairs in the input wiring cable, just leave them attached for later use.

-PB

[denti alligator]

Cool, thanks.

[denti alligator]

Just to follow-up/clarify:

I would use the orange and blue pairs, adding one to terminals 4/1 and the other to terminals 7/10, together with the wires already there?

that can't be right. I'm assuming they need to go to the center terminals A, B, C, and D. Which goes to which?

[Paul Birkeland]

See the bottom of page 38; there are instructions there to remove the orange and blue pairs, in your case, do not remove the orange and blue pairs.

[denti alligator]

See the bottom of page 38; there are instructions there to remove the orange and blue pairs, in your case, do not remove the orange and blue pairs.

Got it. I'm about to wire the these. Which of the orange pair and blue pair should go to A, B, C, and D of the center terminal of the selector switch? Thanks.