Rack-O-Sound?

[cjj]

Well, I've finally gotten around to (almost) finishing my Rick-O-Sound type box. Since it's a rack mount, perhaps it sould be called a "Rack-O Sound" box? I'm not sure just which forum area to put this in, but since it's for my basses (though it'll work with any instrument) and not an actual RIC product, I'll put it in The Low End for now.

(Excuse the messy workbench )

As you can see, it's a bit more complicated than a Rick-O-Sound box...

On the front left are the instrument inputs. This is pretty similar to the outputs on a RIC instrument, Stereo is for Rick-O-Sound on a stereo cable, mono is for a mono cable. These are split into two separate outputs on the back (right side). The switches allow you to swap which pickup goes to which output so you can decide on the fly how you want to process the different pickups. The Mix switch ties the two pickups together (same as Mono, but through the stereo input) and sends the signals to both outputs.

On the back, the XLR connectors are a pair of mixers to take the 2 high and 2 low channels from my Rane AC22B Active Crossover and provide a single high and a single low channel to the power amp.

On the right side of the front is the monitor section. This has a headphone output and the knob immediately to the right controls the volume of the instrument feed which comes from the XLR mixers in the rear. The instrument high and low channels are combined and fed mono-style to each headphone channel (L & R).

Further to the right is another volume knob and an audio input. This input is for a CD, tape, etc. audio source which is mixed into the headphones so you can play along. The volume controls how loud the audio source is.

Here's an inside shot of the guts for the Techno-Nerds...

Edit: New pics...

[Grey]

I don't think i've seen anyone use the Stereo output in a practical situation, and i've always been curious about it. Rick-O-Sound is a staple of Rickenbacker instruments, and i've wondered why it has stayed that way. Surely there must be people who use it because it's remained a standard feature.

[cjj]

Yeah, I use it, probably because it's there. I use both a SansAmp RBI and an RPM, and use one for each pickup. There are times when I like the RPM on the bridge and times I like it on the neck, same for the RBI. So, with this, I can do whatever I want at the flick of a switch...

[Grey]

Yeah, I use it, probably because it's there. I use both a SansAmp RBI and an RPM, and use one for each pickup. There are times when I like the RPM on the bridge and times I like it on the neck, same for the RBI. So, with this, I can do whatever I want at the flick of a switch...

Thats pretty cool, basically an A/B switch on the instrument.

[jps]

Very cool, CJ. Having the built-in headphone amp with aux input is a great idea.

[cassius987]

Nice work CJ! I've been chewing on a really similar idea (slightly different application in a different format) for a few months now. Are the instrument inputs buffered or passive like a "real" ROS box? (Looks like they are passive from the pics.) I like the signal path switching you have included especially.

[cjj]

It's currently passive (just switches and cables) but I'm thinking about adding some high impedance buffers that can be switched in, allowing the option of either passive or buffered.

That's part of the "(almost)" statement about finishing it...

[cjj]

This seems to really fit Forum 51 a bit better than The Low End - It's Non-RIC and basically an "effect", so it's been moved...

[aceonbass]

This seems to really fit Forum 51....

More like Area 51. That's just sick!

[cassius987]

It's currently passive (just switches and cables) but I'm thinking about adding some high impedance buffers that can be switched in, allowing the option of either passive or buffered.

That's part of the "(almost)" statement about finishing it...

If you do that, I'd love to swap notes with you about the ROS/ROS-to-mono buffering method you choose. The best plans I've come up with involve 3 buffers in total, which sounds excessive but seems like what I'll have to do to get the result I want. This is a really cool project you have pursued.

[johnallg]

You put a lot of thought into this project CJ, and it shows in it's versatility and usefulness. Kudos.

[cjj]

It's currently passive (just switches and cables) but I'm thinking about adding some high impedance buffers that can be switched in, allowing the option of either passive or buffered.

That's part of the "(almost)" statement about finishing it...

If you do that, I'd love to swap notes with you about the ROS/ROS-to-mono buffering method you choose. The best plans I've come up with involve 3 buffers in total, which sounds excessive but seems like what I'll have to do to get the result I want. This is a really cool project you have pursued.

3 buffers? Interesting, what are you thinking?

I was planning on just 2 buffers, using the same 2 input jacks with the stereo/mono combine switch in the jack itself (similar to on a RIC instrument - I wanted to do it with one jack, but it ended up being more switches than I wanted unless I ordered something like 1000 of the right type).

Anyway, the buffers would be simply one for each channel/pickup input. I'd do the swapping/ mono mixing/bypass (for passive mode) after the buffers, probably with some small signal relays. That's the beauty of a buffer, very high impedance input - just what you want for a low level guitar signal, and low impedance output with plenty of drive strength for going through cables, switching, etc. I could come up with some sort of auto-sensing circuit to sense the input ring contact being shorted to ground with a mono plug and switching accordingly, but since I've already got both connectors, why bother?

That's actually a down-side to the passive arrangement. Those panel mount rocker switches are pretty much always designed for switching power circuits and don't really have the best contacts for low level signals...

[cassius987]

Having done a bit of research into this idea a few months ago, I have come to the conclusion that you might need a third buffer to sum the first two properly (i.e. running a stereo cable in, each signal gets buffered, then you send them to a mono output--there would be a "summing buffer" between the two original buffers going to the mono jack). Talking to a few people who work in this area full-time has confirmed my suspicions that it might be necessary to get the best sound. Obviously if you go to two separate jacks you only need two buffers, but I wanted the ability to join the signals after separately buffering them... kind of like what happens in the Audere preamp.

[cjj]

OK, yes, that makes sense, going to a single output. In reality though, adding another buffer is no big deal. Mostly it would just meaning using a quad op-amp instead of a dual...

[cassius987]

Well I'm glad you understand it better than I do. This is approaching the limits of my knowledge as far as electronics go. Maybe if you do buffer your system you can explain to me your design later... I would really appreciate that!