Help me lighten my load

Posted: Thu Aug 02, 2007 11:50 am

Yeah...I know - I said I want two different things.

I'd love to have the all-in-one interface. But...I realize that this is impractical at best. Could it be built? Sure. But, the best way to do this (from a business point of view) is to build it in bulk and market it. All of which takes a lot of money!

However, I could get by (quite satisfactorily) with a preamp as I described in quote b above. In fact, this would negate my need for a new control surface and others...

I would be willing to pay a decent price for the 8 channel pre/summing bus/mixer so long as it had the high gain (70+ dB), clean/transparent sound (on par with my existing pres). Again - phantom power not necessary as I'd be willing to do that in a seperate box, but I'm fine if it's in there too.

What are your thoughts?

I've been chatting with another RO'er off-line about this too. I just have to figure out exactly what I want and how much I'm willing to pay for it.

Posted: Thu Aug 02, 2007 12:27 pm

Cucco wrote:

I just have to figure out exactly what I want and how much I'm willing to pay for it.

Exactly. This is the design process. You must first list desired goals (size, cost, weight, cost, features, cost, audio quality, cost, and cost). This narrows the possibilities from infinite to something digestible; then start compromising.

Just remember that the more goals you try to meet, the more you will have to compromise. My current philosophy is to have more task-specific devices. Then I can optimize circuits for its intended purpose with less compromises in quality, size etc.. To this end I have seperate kits: a live archival rig, a session-rig, and a take-no-prisoners-high-end rig.

Posted: Thu Aug 02, 2007 12:36 pm

Zilla wrote:

Cucco wrote:

I just have to figure out exactly what I want and how much I'm willing to pay for it.

Exactly. This is the design process. You must first list desired goals (size, cost, weight, cost, features, cost, audio quality, cost, and cost). This narrows the possibilities from infinite to something digestible; then start compromising.

This I know. After all, I do design weapons systems for our government - it's all a requirements-based setup.

The two things which I've identified have actually been very well thought out. They are just two separate and different desires. Both are valid and I would purchase both. However, one is more obtainable (the 8 channel pre with mix/sum bus). The other is a pipe dream that I wish someone would develop (and I would buy!)

My huge gripe is that many companies offer some kind of 4 channel preamp with a summing buss included (API, Benchmark, others.) However, I often need more than 4 channels!

I'd LOVE to start recording in 2 track only (rather than having 4,6, or 8 tracks rolling) but...
1 - I don't want to use a standard mixer to do this for two reasons -
A - I don't trust many brands of mixers available to me to not destroy the sound from the preamps
B - I don't want to have to lug a heavy mixer in addition to what I have to carry currently.
(The API external mix bus looks like a good solution/alternative though.)

The other reason I don't mix to 2 track in the field is because I don't trust what I hear in the field. Since 80% of my mixes are done through cans on location and I simply don't trust cans, I don't want to take the risk of a horribly mutilated recording due to a piss-poor monitoring situation.

I can kind of get past that last reason since I'm finding myself trusting myself (not the cans) more and more as time goes on, but that initial feeling of letting go is always a scary one.

Posted: Thu Aug 02, 2007 12:51 pm

Cucco wrote:

This I know. After all, I do design weapons systems for our government - it's all a requirements-based setup.

I figured so. I wrote that for others reading these posts. And also to elicite more specific requirements from you. Something like...

It can't weigh more than 117 pounds,
It must have 4'' diameter bakelite knobs.
It must be transformer coupled, tube gain with no negative feedback.
It must be purple and lime green.

You mixer is totally buildable. One suggestion that I would offer is this: NO PAN-POTS. This will reduce the complexity greatly and allow a much cleaner signal path. Have an L-C-R buss assignment switch instead. I have done without panning for 8 years now, and there is no lack for spacious width and depth in my recordings, rather there is more.

Posted: Thu Aug 02, 2007 1:02 pm

Interesting...LCR buss - this is a great idea!

Okay, so here's my list of requirements -

Stepped attenuation. (prefer stepped switches, but will accept high-tolerance stepped attenuators)

3U or less

Solid build - max weight 35 lbs (yes, I know that's heavy as hell!)

Must be all XLR in/out all operating balanced at +4.

I don't have any preferences as to whether it's transformer/transformerless (but I don't like that prick Optimus Prime...such a do-gooder...) or tube. I'm more interested in a clear sound than the topology and while I know the sound is directly affected by topology, I also know that any of these topologies is capable of a clean/open/transparent sound.

I would prefer an internal 110vac power supply but would accept external if necessary or significant improvement could be had.

I would prefer the unit to cost less than $4000. (negotiable).

I would need direct outputs on all 8 channels as well as the 2 channel mix bus.

Metering is not essential as I do this elsewhere anyway and unless it's comprehensive metering, I find it to be useless. Besides, I also assume/expect it to be very unlikely to overload the input stage.

Does that help a little?

Posted: Thu Aug 02, 2007 1:23 pm

Stepped attenuators: Built up Elma 24-pos (times eight) will easily eat up $600 alone, but will provide better quality than pots. What resolution (2dB per step?)

3U/35lbs.: Liberal! Allows for many design options. Cool.

Clear Sound: Well, tubes are more clear but not reliable in live situations, probably better go solid state.

PowerSupply. I only make external supplies. But the mixer could be 2U and the ps 1U = 3U total.

Direct outs: Will you have seperate mixer faders? If so will the DI follow the fader or are they pre-fader?

If we assume that the control surface will be a 2U rack unit, draw a lay-out of how you would like the controls arranged.

Posted: Thu Aug 02, 2007 1:32 pm

Zilla wrote:

Stepped attenuators: Built up Elma 24-pos (times eight) will easily eat up $600 alone, but will provide better quality than pots. What resolution (2dB per step?)

That would be fine...but with only 2dB per step and a total gain of 70dB, that would only give me 48dB of gain range with a minimum of 22dB. Unless of course you had a 20dB pad as well...
The tighter the control, the better, so 2dB is fine if there was a pad or some other means of controlling that last bit of gain.

Zilla wrote:

3U/35lbs.: Liberal! Allows for many design options. Cool.

Yeah...I know. Of course 15 lbs would be MUCH better, but weight is not my biggest concern...

[quote="zilla"]
Clear Sound: Well, tubes are more clear but not reliable in live situations, probably better go solid state.
[/qutoe]
Agreed. Besides - I have to deal with clumsy interns sometimes. I could just imagine a short drop and the sounds of glass shattering. Bye-bye $200 worth of tubes (or more depending upon what variety...)

Zilla wrote:

PowerSupply. I only make external supplies. But the mixer could be 2U and the ps 1U = 3U total.

No beef there. It fits in the requirements.

Zilla wrote:

Direct outs: Will you have seperate mixer faders? If so will the DI follow the fader or are they pre-fader?

Do you mean "Will the direct output follow the fader..." or did you mean DI?? I would think there would need to be a seperate gain stage - input gain (70dB gain range with stepped switches) with the outputs working post this gain stage. The second gain stage would be attenuation only and would operate as the mix buss gain stage. This should probably be continuous (non-stepped) and follow behind the direct outputs (outputs pre-fader - mix-buss post-fader). Am I stating this clearly? I know what I mean, I just don't know if I'm describing it exactly the clearest.

Zilla wrote:

If we assume that the control surface will be a 2U rack unit, draw a lay-out of how you would like the controls arranged.

I will try to do so in the very near future and post here when completed.

Posted: Thu Aug 02, 2007 1:56 pm

Yeah, I meant DO, not DI.

So the signal path is like this?...

MicPre: Balanced in, no phantom
a) 12-60dB gain in 24steps @ 2dB/step, addition +10dB boost circuit.
b) 12-60dB gain in 12steps @ 4dB/step, addition +10dB boost circuit.
[ a has more control, b is half the cost]

Direct Outs: Independent of Mixer [Post-MicPre, Pre-Mix Channel Fader]

Mix Channel Fader: feeds mix buss via L-C-R switch (Unity/-infinity pot).

All Outputs balanced +4dBu

No metering or monitoring positions.

Posted: Thu Aug 02, 2007 2:13 pm

Everything looks about right to me.

The only exception is:
"No...monitoring positions"

I would like a headphone amp strapped across the 2-buss output. Sorry - forgot to mention that.

J.

Posted: Thu Aug 02, 2007 2:42 pm

I wonder...

Would this make it even more complicated...

How difficult would it be to add 8 additional channels of line source only? Single gain stage with the same pan controls?

Obviously, I'd be willing to move up a RU or 2.

Posted: Thu Aug 02, 2007 3:22 pm

Cucco wrote:

How difficult would it be to add 8 additional channels of line source only? Single gain stage with the same pan controls?

8 inputs: mic/line switchable
-or-
16 inputs: 8 mic, 8 line

are the line inputs balanced?

Posted: Thu Aug 02, 2007 4:31 pm

Interesting topic - as I am turning 60 next month I too want to limit what I am carrying.

Can someone point me to some information on the Rabbit Preamps?

Thanks
Larry Elliott

Posted: Thu Aug 02, 2007 4:44 pm

I believe they are the ones designed and built by our own Zilla.

BTW - Zilla -
I would think that I would want 8 pres, 8 Line ins (balanced) versus 16 pres. I think this would give me the option of adding "colorful" pres later if so desired.

Posted: Thu Aug 02, 2007 5:49 pm

@ lell010 - The RABBIT pres are my own design and build. They are battery powered, stereo mic pre's for use with passive mics. I also have a version which will work with ccm and cmc type schoeps. They are about 3x4x6'' in size. There are other threads about it.

@ Cucco: So then its 16 total inputs? (sorry, still not sure). The problem with having balanced lines is that you need an active stage to receive it. I cannot think of any line receiver which will not have some kind of color. May I make another suggestion? Drop the balanced line req. If you stayed single ended on everything (except mic inputs), you would eliminate 50% of the electronics. This saves $$$ and removes any colorations all together. I have been single ended for some time and cannot report hum or other emi type problems. YMMV.

Posted: Thu Aug 02, 2007 8:23 pm

Yes - 16 inputs - 8 mic, 8 line.

I'm perfectly fine with single ended. In fact, my cables are likely to never be longer than 3 feet (usually less than 12")

I would still want the +4 level.

I suppose the best way to wire this would be:

hot to hot
balanced neg to unbalanced ground
balanced ground float (or strap to unbalanced ground - either way)...

Does that make sense?

Edit...

I mean to say - when connecting between the unbalanced I/O on the unit and balanced I/O on other units.

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