[DESIGN] A little monitor controller for you

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> It indicates the phase of what relative to what?

Hang a zero-center meter across (unbalanced) Left and Right channels. A Mono signal will read dead-center. Stereo all in one side, near max level, will throw the needle to that side. Typical panpot stereo will show large deflections, both sides, depending on mix balance.

A variation uses two rectifiers, average or peak, to give a slightly different view of the same thing.

An X-Y o'scope (turned 45 degrees) fed L-R gives a more detailed view of "Phase" matters. Generally too detailed, and sticks too far out the back of the console.

"Phase" is perhaps the wrong name. It indicates the amount of out-of-phase or difference level between two stereo channels. Since good mastering engineers are not always picky tech-persons like me, the name is not too important. In operation on a stereo signal, you come to understand what various "Phase" wiggles mean.

100uA-0-100uA seems a good match to 200uA VU meters. 0VU is more like 140uA, and you don't usually want the difference level to be as high as the channel level. (In wax-cutting, you sure don't want huge difference {vertical} signal; that's unimportant in tape or CD but you do want a "nice" amount of difference for good image spread.)

Unless there is a multiplier in there, it will always read near-zero for low levels. That may not matter if you are mastering always-loud material.
 
Hi,

Thanks Viitalahde!
Just the thing i need to replace the ancient 1202 mixer.

I'm new here and new to diy, so far built me a tube guitar amp from ax84.com and a booster pedal.

My source is a Lynx L22 (Ouput impedance:balanced 100Ω, unbalanced 50Ω. Output Drive Capability 600Ω impedance, 0.16 µF capacitance) and its destination is an Alesis RA100 (bought used, online manual's spec page is oddly blank but it does mention elsewhere that it's inputs are unbalanced).

Would part values need changing if i left out the mode switch? Would a 1k potentiometer work as well as the stepper? Could those 3 input resistors not be replaced with just 1 that is placed between selector switch and pot/stepper?

Finding parts is so headache inducing, any part suggestions would be a great help.

Thanks,
Tony
 
The only problem i have with stepped attenuators is my lack of experience with them and availability. But i won't let that stop me now that i've found this great forum :grin:

I have no idea what i should be looking for. 2 deck? 4 deck? number of positions?

Found this one: ELECTROSWITCH 4-Deck 23 Position (silver contact). Is good?

If 4 deck is for balanced stereo maybe it's a good idea to get that one since i know i need to replace the destination ampifier.

Thanks,
Tony
 
Also, be sure to get a shorting (make-before-break) type switch for your stepped attenuator.

If you go with the series resistors on the selector switch as I strongly recommend you do--see earlier comments--then I suggest a straightforward 1K potentiometer-type stepped attenuator as opposed to the various 'H' and 'L' types like you see on the Goldpoint site. Their 'V' type is an example of a potentiometer.

Here's a potentiometer calculator:
http://www.quadesl.com/attenuator.html

...or you could just take the values of the Goldpoint page and scale them to 1K.
 
[quote author="Guest"]An 1k pot would not work well because they have tracking problems - a stepped attenuator is much better.[/quote]
is that true for 'better' pots like the ALPS RK27112 ?

because i want to make a box with a pot ( i wouldn't call that a monitor controller ) to use my monitors with my computer without having to power my desk only for that. but if that's a bad idea i'll rather skip it. listening to headphones or cheap computer boxes at low levels i have often noticed the left side was louder than the right one, and i wouldn't want something like that for my monitors...
 
It is true for any dual gang log pot. Even the best ones. Best case they have 5% error.
My stepped attenuators have no more than 0.02dB error at any level position. Of course you have to match resistors, but it worth the time.

chrissugar
 
I really can recommend mikkels relay attenuator project..

that is a really good alternative and you have way more steps
as with a rotary switch..

www.dantimax.dk
 
i think this would be overkill for me, at least for the moment. i read quite a bit of a thread in the sos-forums linked somewhere here, and it looks really nice, but i've some other stuff to finish (and repair :sad: ) and i better not begin anything else before i've done that.
 
I can confirm that Mikkel's attenuator is excelent. Measures great and sounds great. I built one. :grin:
If you want to keep it simple for the moment build a mechanical stepped attenuator, and maybe later you can do Mikkel's one.

chrissugar
 
Wow, my old thread was upped.

Actually I'm working on a new mastering console right now - basic stuff with process path selector, monitor source selector, 5k stepped attenuator, process attenuators.. But it will have insert points too, so now I can keep the signal path nice and compact when stuff's not in use.

48 XLR's. :twisted:
 
IMHO it is good way to go with separate monitor/patch/router and process chain...
mon.jpg

tfr.jpg
 
first Capital letters, then no sandals and then suit and tie for work
it's a sliperry slope.
 
Igor, I saw your controller while browsing through diffent threads on this topic. It really looks excellent :thumb:
 

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