I want to build my own old-style, constant-impedance stepped ladder
mixer controls. (Please, let's not get into a debate about WHY). It
seems the only rotary switches available at less than "audiophile"
prices are 24 positions maximum. So, one could make a control with 23
2dB steps and "off." I know that 2dB/step controls were once fairly
common, and my question is to those who have used mixers thus
equipped. Did you find that 2dB steps gave adequate control of your
levels, or did you find yourself pining for the costlier 1.5dB/step or
0.5dB/step controls? Thanks in advance for all replies. --Dave

In article ,
NewYorkDave wrote:
I want to build my own old-style, constant-impedance stepped ladder
mixer controls. (Please, let's not get into a debate about WHY). It
seems the only rotary switches available at less than "audiophile"
prices are 24 positions maximum. So, one could make a control with 23
2dB steps and "off." I know that 2dB/step controls were once fairly
common, and my question is to those who have used mixers thus
equipped. Did you find that 2dB steps gave adequate control of your
levels, or did you find yourself pining for the costlier 1.5dB/step or
0.5dB/step controls? Thanks in advance for all replies. --Dave

I use 2dB/step controls all the time, and they are fairly convenient
but they can be a pain for mixing. For main mix controls, I would prefer
a finer step, but I could live with 2 dB/step and I did for years.

For trim controls and for buss level controls, you can take something MUCH
coarser. The 12-step C&K pots from Digi-Key are even sufficient. I like
the 12-step pots for sweep frequency controls on the console EQ also.

Be aware, though, that with a modern system you can build a single-ended
mix buss and use stepped ladder potentiometers (half the resistors that
you have in a full L-pad) and get similar noise performance. Feels the
same way, works the same way, costs a bit less.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

NewYorkDave wrote:

I want to build my own old-style, constant-impedance stepped ladder
mixer controls. (Please, let's not get into a debate about WHY). It
seems the only rotary switches available at less than "audiophile"
prices are 24 positions maximum. So, one could make a control with 23
2dB steps and "off." I know that 2dB/step controls were once fairly
common, and my question is to those who have used mixers thus
equipped. Did you find that 2dB steps gave adequate control of your
levels, or did you find yourself pining for the costlier 1.5dB/step or
0.5dB/step controls? Thanks in advance for all replies. --Dave

It's actually one of life's little jokes I think... if you are using a
stepped attenuator, you are going to find ocassions when you need to hit
between the steps (actually, not true for broadcasting, but everything
else!) Never fails. (I've never had the luxury of using 0.5dB per step,
so maybe there really is a "good-enough".)

The RNP, if I remember, has 6dB per step, which on the surface seems a
bit scaryG...

And then you get to what's practical. I really like stepped attenuators
for a lot of reasons, repeatability, precision, ability to match
channels, etc. So I live with the trade-off of reduced resolution. And I
have certainly had situations, especially mixing, where extra resolution
would have been nice, but I've always been able to work around it.

Bill

On 18 Jul 2003 06:50:42 -0700,
(NewYorkDave) wrote:

I want to build my own old-style, constant-impedance stepped ladder
mixer controls. (Please, let's not get into a debate about WHY). It
seems the only rotary switches available at less than "audiophile"
prices are 24 positions maximum. So, one could make a control with 23
2dB steps and "off." I know that 2dB/step controls were once fairly
common, and my question is to those who have used mixers thus
equipped. Did you find that 2dB steps gave adequate control of your
levels, or did you find yourself pining for the costlier 1.5dB/step or
0.5dB/step controls? Thanks in advance for all replies. --Dave

If you can use two switch stacks, you can have the best of both.
Also, it's common to have varying steps, smaller at the top for
playback use, for example. Good luck; a very worthwhile project.


Chris Hornbeck,
guyville{at}aristotle{dot}net
question Authority

"NewYorkDave" wrote in message
om
I want to build my own old-style, constant-impedance stepped ladder
mixer controls. (Please, let's not get into a debate about WHY). It
seems the only rotary switches available at less than "audiophile"
prices are 24 positions maximum. So, one could make a control with 23
2dB steps and "off." I know that 2dB/step controls were once fairly
common, and my question is to those who have used mixers thus
equipped. Did you find that 2dB steps gave adequate control of your
levels, or did you find yourself pining for the costlier 1.5dB/step or
0.5dB/step controls? Thanks in advance for all replies. --Dave

I do a lot of mixing in Cool Edit, where the fader is marked off in 0.1th dB
steps. IME the range from "way too much" to "way too little" when mixing
multiple voices that are supposed to blend is about 3 dB. 0.5 dB steps are
about the smallest steps that can be heard. Seems like steps someplace
between 0.5 and 1.0 dB are about as coarse as I could stand to work with.

(NewYorkDave) wrote in message . com...
I want to build my own old-style, constant-impedance stepped ladder
mixer controls. (Please, let's not get into a debate about WHY). It
seems the only rotary switches available at less than "audiophile"
prices are 24 positions maximum. So, one could make a control with 23
2dB steps and "off."

[snip]

Well, you could also have two or more ladders with different steppings
and switch between them -- say, one with finer steps on the low end
and another on the high end. It would make your dial legend messy
as hell, add more switch contacts to your signal path, and be otherwise
ugly (etc....) but you might get a more flexible control.

-DrBoom

In article writes:

I want to build my own old-style, constant-impedance stepped ladder
mixer controls. (Please, let's not get into a debate about WHY). It
seems the only rotary switches available at less than "audiophile"
prices are 24 positions maximum.

That's about all the stepped attenuators were, give or take a few
steps.

I know that 2dB/step controls were once fairly
common, and my question is to those who have used mixers thus
equipped. Did you find that 2dB steps gave adequate control of your
levels

Sure. Set them them and let the band play. It was rare to ride a fader
in those days because (a) musicians played at the right level when
they found it, and (b) you didn't have tracks all compressed to
essentially the same level (you didn't have tracks at all, really) so
that .5 dB made the difference between being heard and being buried.

I assume this is either for scientific or nostalgic reasons. If for
the former, you probalby won't be winding the faders up and down
during a mix, (if it was necessary to do a fadeout, there might be one
"high resolution" fader, but that was on the mastering console, not
the recoring console). And if for the latter, then do it like they
used to.


--
I'm really Mike Rivers - )

Thanks for the great replies. Please keep 'em coming.

By the way, although I didn't let on in the original posting, I am
aware that the old mixer controls usually had a fairly steep taper to
infinite attenuation on the last few steps.

In the '61 Langevin catalog (now available as a decent-quality reprint
and great reading, by the way) they offer two basic ranges of
attenuation steps in their rotary mixer controls. The higher-priced
option is 30 1.5dB steps, recommended for critical use, and the
cheaper is 20 2dB steps recommended for economical use in portable
equipment. The catalog text seems to imply the 2dB steps are OK for
many uses, but 1.5dB is recommended for smoothest control.

With a 24-position switch, you'd have 23 positions plus "off", three
more positions than Langevin's lower-priced rotary mixer. This could
buy you a little more resolution down at the low end before the
tapered steps. I haven't confirmed this directly with Elma, but a
friend tells me that they sell 24-pos., 1-pole MBB rotaries for less
than $20 each. This would work fine for an unbalanced ladder with a
minimum loss of 6dB, which seemed to be the most common type mixer
control back in the day.

Buying the "real deal" just isn't a viable option for the 12-channel
DIY mixer I have in mind. New Shallcos or old stock Davens are just
too damn expensive to use in that sort of quantity.

--Dave

By the way, here's how Goldpoint uses 24 steps:

http://www.goldpt.com/info.html

It's a table about halfway down the page, under the heading "How Many
Decibels Are Used Per Step (Taper)?"

As you would expect, it's 2dB steps for most of the range with the
last 7 steps tapered to infinity.

These attenuation values should be useful, even though I want to build
a constant-Z ladder, not the potentiometer-type "audiophile" control.