passive monitor a/b switch?

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Chris_Avakian
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passive monitor a/b switch?

Post by Chris_Avakian » Tue Sep 25, 2012 7:56 am

anybody got any good plans? doesnt have to be balanced, 3 outputs would be awesome.

Greener
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Post by Greener » Tue Sep 25, 2012 8:10 am

You need a variac and some clamps...

dfuruta
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Post by dfuruta » Tue Sep 25, 2012 9:18 am

Are you switching the signal before or after the power amp?

If you're before the power amps (ie each set of speakers has its own amp), you could use one switch for each amp. Switch the amp's inputs to the signal when you want those speakers on, and connect the amp's inputs to ground when you want them off.

After the amp, seems like you could just get a switch with a reasonable power rating to select which speakers you're connecting. You'd want to switch both hot and "cold", and you need to be careful not to accidentally connect the amp's output to ground. You could use relays if you want to be slick.

rockstudio
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Post by rockstudio » Tue Sep 25, 2012 12:51 pm

I made one that switches between speakers after the power amp. It is very basic, but also slick, just a small toggle switch and LED on my desk, the actual switching takes place by relays near the amplifier. I can draw it out for you if you wish.

Chris_Avakian
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Post by Chris_Avakian » Tue Sep 25, 2012 9:50 pm

dfutura. that idea is brillaint. thanks. im going to try something like this out soon.

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Jeff White
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Post by Jeff White » Wed Sep 26, 2012 9:03 am

I just went through getting away from a speaker switcher scenario. Long story...some background...

I purchased a pair of NS-10Ms and a Hafler P-3000 Trans Nova back in 2007. I picked up an Adcom GFS-3 speaker switcher and hooked up a pair of Yamaha NS-6490 ($100/pair) hi-fi speakers to the system. This was an immediate move from those dreaded Alesis M1mk2 powered monitors. Anyway, the P-3000 had a wonko left channel that I had to attenuate up about 4-6dB on the front to match the right side, and the low end would distort a bit on the 6490s (more low end than the NS-10s). I couldn't find a repair guy, so I picked up an Adcom GFA-545 to replace the P-3000, which I just put in storage. In 2009 I ended up borrowing a pair of Genelecs for a little while and then replacing the NS-6490s with a pair of Axiom M3s. So now I had the NS-10Ms and the M3s powered by the Adcom and switched via the GFS-3. The Genelecs were around for a project and were powered, so I just created an Aux in Digital Performer and routed signal to them via software.

This all changed in May of 2010, when I found a pair of vintage Rogers Studio 1 monitors in the trash here in Philly. Unreal speakers. All drivers were perfect. Once I acquired the Rogers (which can handle from 25-300 watts) and switched out the Axioms M3s (not enough power for tracking anyway) that they replaced, I noticed that the NS-10Ms were like 6dB louder than the Rogers (wasn't an issue with the Axioms). So I basically had to turn up or down my overall volume BEFORE switching speakers. It was a total PITA, but the Rogers are insanely great speakers, and I like to check mixes on the NS-10Ms. Also, the NS-10Ms started sounding like shit to me at higher volume (brittle, sharp), and I have always been super into these speakers (see my past posts defending them), so there was a general WTF? happening every time I switched to them. *sigh* And now I was using a software bus to hardware in Digital Performer to send audio to my mono Avantone MixCube, which I picked up this year. Relying on a hybrid of an interface volume control and software and STILL having imperfect switching due to the balance between pairs being off was really getting to me.

So what was my solution to the 6dB issue and the NS-10Ms sounding brittle? I considered a Presonus Central Station, but didn't want to spend the extra cash on a one-trick pony. Then I was at another sweet studio here in Philly this summer, and the only monitors (at the time) that were set up on the console were a pair of NS-10Ms. And guess what? They sounded amazing. Here I am at home with a pair that sound like shit, and these things sound incredible. I asked about the power amp, since I figured that this was the only thing that could possibly be different (I have decent clock/converters/cables). Hafler P-3000 Trans Nova. Well I have one of those! Let's see if I can work around its issues.

So I decided to figure out a way to send analog signals out to a pair of power amps, each powering a different pair of speakers. Figured that I would have to go completely software-based and employ mutes, soloing, or virtual faders. This kind of scared me a bit. It just so happens that at the same time all of this was going on about 2-3 weeks ago, I was also hunting for a small format mixer for my new live keyboard/lap steel rig for tour (sending all of this stuff to a guitar amp...another long story). I found a Mackie Onyx 1220 with the firewire card on eBay for...$170 shipped. I bought it. Once it arrived I decided to test it out thoroughly, so I pulled the speaker switcher out of the equation and hooked up my Rogers to it and BOOM!, holy shit, it was like a wet blanket was lifted off of them. More 3D, crisper, cleaner...I had folks over to hear the difference. Amazing. So now I hooked up the NS-10Ms to the Hafler (attenuated properly using the front panel gain knobs, and thankfully don't go low enough for the low end to distort) and ran those from the Mackie. Sounded as good as I remember them sounding at the other studio. What an incredible discovery.

That little Mackie Onyx 1220 has totally changed my monitoring situation. I come out of my interface and directly into a stereo channel (EQ can be defeated on the Onyx with a switch). The Onyx also has an extra set of Aux Sends built into the MUTE switch (Aux 3-4), and you can send this Aux pair to the Control Room volume. So the Rogers get assigned to Aux 3-4, sent to Control Room volume, and then sent to the Adcom amp via the Control Room outputs. The NS-10Ms are fed by the Main 2-Bus. What this means is that the input gain on the stereo channel strip is set to unity, and then the stereo channel fader is set to unity, and it goes to the Master fader, which controls the volume of the NS-10Ms going to the amp via the Mackie's main outs. So, the Adcom amp/Rogers get fed via the Control Room outs, and the Hafler/NS-10Ms get fed via the Main Outs. I engage the MUTE/3-4 switch on the stereo channel, and the NS-10Ms are muted and the Rogers are engaged. And their volumes are attenuated so that they match because each pair of monitors now has its own volume control. What a novel idea. And then Aux 1 on the stereo channel strip gets set to unity gain and sent to the master attenuator for Aux Send 1 (oh look another volume control), and this feeds, in proper collapsed mono, the Avantone Powered MixCube. So all 3 sets of monitors have their own volume control now, as well as their own tailored power amp. And I could not be happier with this set up. It sounds awesome. It is a joy to have a small analog mixer in the studio once again as well.

The Mackie ended up being too large for the road rig anyway, so I ordered an Allen and Heath ZED 10 off of Amazon (with a year to pay it off no interest), and it's a great road-ready size and does what I need it to do for my live rig. I experimented by swapping out the Mackie and running the studio monitor setup off of the ZED and, honestly, everything sounded thin. It was also a PITA to properly send audio to 3 unique monitor setups with the ZED (2 would be fine), and the EQ is always active in the channel strip. I tried to make it work and had high hopes going in, but the Mackie slays the ZED for studio monitoring.

Hope that this somehow helps out.

Jeff
I record, mix, and master in my home studio, Ch?teau Blanco, and in various spaces in the Philly area. http://jeffwhiteaudio.com/

dfuruta
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Post by dfuruta » Wed Sep 26, 2012 11:10 am

That's good advice!

If you want to build your own volume controls, I put up a thread in this (DIY Gear) forum a little bit ago about how to do that. If it's just for a speaker switcher, it could be even simpler: once you figure out how much more attenuation each amp needs than the other for the same perceived volume, you could just drop in a fixed voltage divider per amp and avoid any problems with switches wearing out/settings getting changed/whatever. Then, just use your main monitor controller (or software, or whatever) to adjust the overall volume; the correct balance between the amps should stay fixed.

Chris_Avakian
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Post by Chris_Avakian » Mon Oct 01, 2012 5:08 am

you guys arent making this look as simple as it sounds one bit. for now, atleast until i do some more research switching by using the control room output, and the studio output on my console is sounding pretty good right now. lol

until that last post i had no idea is was this complex an issue. i'll have to take a whole new look at all this, but that info is extremely informative!

thanks for every ones input!

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