R/E/P > Brad Blackwood

For those with passive monitor attenuators..

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What are you using?

There will be a 3rd and final console I'm about to build. I want to improve the mechanical quality by going from Elma switches to the great, sturdy Russian switches I've been using lately.

But most of all I want a bridged-T attenuator. Right now I have a 5k L-pad attenuator, 23x 2dB steps + dim. The new one will be built on a Shallco. I reckon something like 2k5 would be a place to start with Z values.

Since this is going get into general console discussion anyway, let me ask one more thing:

How many of you are using something more extended as a "console" than a monitor volume controller?

I switched to the current console about two years ago, and I personally love having all the bypasses at one single place. The amount of cable is for sure larger with all these sends & returns, but it's not often I have everything patched-in.

Hi Jaakko, does shallco offer ready made attenuators or just the switches?

Im pretty much in the same situation, but ive been lookin at the goldpoint att.
And my monitor section will have more functions than now.

Andrew Hamilton:
Shallco offers both ready-made attenuators at custom Z values, as well as the naked switches.  I'm using a Shallco-made 5k Ohm bridged H-pad (which is a differential path T pad).  According to Nelson Pass, the Pass Labs amps with SuperSymmetry actually sound better with differential sources, rather than single-ended ones, and he confessed to me that he has never been in a mastering studio that wasn't entirely wired differntially.

The use of bridged-T or -H pad lets you minimize the number of resistors in series to 2 (per leg), at all steps of the switch.  So, very quiet settings will not have more Johnson noise (; than higher loudness settings, as is the case with series-types. Also, the impedance seen by both the source and the destination does not change when switching steps with this type of circuit, so one can focus on the sound of the loudness differences without much interference from other voodoo.

The Lavry M•DA-824 can drive a 600 Ohm load, and Dan told me that 2k Ohms would be the theoretically ideal loading for that DAC.  So, I had a 2k Ohm balanced passive attenuator made by GoldPoint Audio which worked nicely for a while.  I preferred the sound of the CraneSong Avocet to that.  But after DC insisted that passive, when loaded properly, is "essentially blameless," I splurged for the $600 Shallco bridged H.  Of course DC was correct - at least according to my listening tests.  The Shallco 5k H pad is sonically invisible!  Loving the lack of color.

After I sold the Avocet, I had over $1500 left over to buy other things with.  I did implement a source switch, as well as an independent mute switch for left and right channels.  5k is what DC recommended as a good compromise between performance and flexibility,  and it is not much worse than 2k for human hearing requirements, as long as the cable is ultra~low capacitance and the leads are as short as necessary to reach the amps, and 5k does provide a little extra resistance for wimpy sources one might wish to audition on the same setup.  (Fwiw, I'm all Mogami 3080 right now, which is 14 pF/foot).  


P. S., I'd like to know if anyone has modified their differential inputs and outputs on mastering gear to be single-ended and what was entailed as well as any gotchas.... I was once instructed to bypass the balancing stage (as well as anti-RFI components) of the inputs of a Dominator II by one of our resident electronics gurus, fwiw.  This was only to improve the purity of the sound, which I think it did.  But, it was on a multiband clipping limiter, so sound quality is a relative thing, right?  

Since mastering studios are usually quiet and specialized environments, why is so much mastering equipment differential?  There are a few notable exceptions for off-the-shelf gear, such as that made by Pendulum, which is deliberately single-ended.


cass anawaty:
I use the Goldpoint SA1X.  Very happy with it.

I recently had a 10k:5k (full) H pad made by Shallco. I asked for a bridged H and they quoted me on that. Then they realized they only knew how to do an unequal impedance as a full H. So that is what I got. Apparently I was the only one who ever asked for that. A 12 deck switch for stereo. I got 30 position with 1.5dB per step. It's very impressive looking. I have a big knob for it.

I don't have it installed yet. I have meters on the way. They are all custom order Sifams. VU, PPM and correlation meter. All white background with black scales. The correlation meter is a vertical orientation edge meter. I got gray masks for the Clarity series VU and PPM and extra bezels for the edge meter which I will attempt to paint gray. It should be very pretty.

For bypass the grand plan is to have relays in the gear but control centrally located.


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