Low synth output

Simpler to just slap them into a DI box and use the mic inputs? When I face something a bit lower than usual, like one of my guitars that has trouble plugged into the instrument input of my interface, I just add a compressor in Cubase, with no compression dialled in, enable it and then turn off the auto makeup gain, and turn the knob - it works rather well and I can't detect any noise issues as long as I don't start dropping the guitar volume even further. I would try something like this before spending money.
If the OP was going to do that he may just as well use the line inputs on those channels since those have the gain needed to get the VU meter levels where he wants them. It's the stereo channels 5-12 that are 1/4" inputs that don't have the gain to get where he 'thinks' he wants the levels to be.
He's trying to use the mixer as a 'patchbay', leaving cables from different synths plugged in and only enabling the channel(s) that he wants to record sent to the interface. As long as the mixer doesn't throw any noise in he can makeup the gain he doesn't have with the gain control of the interface.
 
When the cats away the (gear mice) will play. So..

I had a ZED14 sitting unused in my attic (long story) and someone on gearslutz told me that unit had gain knobs on mono AND stereo channels. So I hooked it up right next to the Mackie and did a side by side: the same synth voice at max volume into the stereo channels of each, both in pre-fader-listen mode so I could see raw input levels. It was an oboe sound so nothing spiky and I kept keyboard velocity the same.

With the ZED gain at 0 the ZED had a slightly higher reading but not much. With its max +10db gain the ZED level was just over 0. I did the same test with another synth and had a similar result, both synth outputs were reading around -20 and needed gain. I don't know much about this but from the little I have read on gain staging, starting with a -20 signal is probably not good.

So I may go with the ZED now and I doubt I'll need +10db on every synth or voice but it will be nice to have it. My old Ensoniq voices are loud and wild. Yes I am using the mixer as a patchbay I am old school. Also the ZED also seems to have less color than the Mackie but I'm not sure yet.

I have to read up as this discussion is very interesting, thanks and sorry I was absent ha.

I have found a lot of threads about synths having low output levels which people have tried to address by tweaking voice levels and global synth parameters. I can see that causing me more headaches than adding a gain control.
 
Thinking on....I dare say a lot of synths just use a single 5V* supply for the logic circuits and CPU?

That would give an absolute maximum output of +5dBu and so "operating level" would need to be 20dB below that so the common -20dBV/u figure found makes sense (crap audio engineering but makes sense!)

*Many can use a 9V wall rat PSU but since they are commonly USB bus powered that 9V is smashed down to a regulated 5V.

Dave.
 
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I suspect the standard is simply to allow connection to guitar amps, nothing cleverer.

I suspect that's the case, or that instruments like the Fender Rhodes used magnetic pickups that were already compatible with guitar amps so that became the standard for keyboards. If you change from -20dBV output on one product to +4dBu on the next, customers are going to be confused and angry.
 
I suspect that's the case, or that instruments like the Fender Rhodes used magnetic pickups that were already compatible with guitar amps so that became the standard for keyboards. If you change from -20dBV output on one product to +4dBu on the next, customers are going to be confused and angry.

Yes well, but at an original price of nearly $1000 you would think they could have stretched to a switch and a couple of resistors!

Dave.
 
Yes well, but at an original price of nearly $1000 you would think they could have stretched to a switch and a couple of resistors!

Dave.

It would have been easy to do, but I think it would have confused people rather than met a market need.
 
Really? Don't recall any confused gitists regarding the FX loop +4/-10 switches on most of "our" amps? Not talking drummers here?

Dave.

That changes the operating level of both input and output. If it's in the wrong position you get more noise or more distortion. Maybe a lot of players just wouldn't notice anything other than having to turn a compressor threshold or distortion gain to some extreme position. I bet a lot of guitar players had no idea what it did.
 
Continuing! So I am now using the ZED14 which now has 5 synths going in via both mono and stereo inputs with a balanced cable from the Aux 1/2 out to the interface. I'm gain staging from synth to mixer to interface to DAW as follows.

- set synth to almost max volume
- engage PFL switch
- adjust channel gain to get mixer level bouncing around or just hitting 0 (about +10db)
- disengage PFL
- engage Aux 1/2 headphone switches (is that for headphones?)
- set master Aux 1/2 to 3/4 position
- set channel Aux 1/2 to 3/4 to get mixer levels same as with PFL
- 0 gain on interface
- meter levels in Reaper are around -18Dbfs

So a question: is matching the Aux 1/2 meter levels to the PFL meter levels ok? Is this achieving unity gain? It's interesting that with the interface gain at 0 I got the exact DAW reading as in the attached pic.

FYI

1) all 5 of these synths in PFL mode with 0 mixer gain were giving levels at -20 to -20 db so it wasn't a matter of re initializing, though that was a good idea.

2) only one synth, a Yamaha CSR6 is actually noisy so the comment about OCD'ing on a nonexistent noise issue was prob right

gain-staging-studio-recording.png
 
It seems like you're closer to where you want to be.

What that pic doesn't cover is line level. Most mixers will put out a +4dBu signal when the meter reads 0dBVU, and most converters will correlate that to -18dBFS. Mackie boards are weird in that 0dBVU produces 0dBu at the output.

The 0dBVU/+4dBu/-18dBFS level is an "average" level. The signal should be crossing that fairly regularly, not spending most of its time above or below it. But it depends a lot on the instrument being played. A strong piano note would peak well above that level, drop rather quickly to something near it, then trail off below it. A strong drum hit might go to +12dBu (-6dBFS) then drop off rapidly. A strong violin note might go to +3dBu and stay there until the musician stops playing the note. A vocalist might be right around 0dBu on normal sustained notes and +6dBu on louder notes. This is all approximate, just as a guideline.

With properly matched hardware you should be able to have the channel and master faders on or near the 0 mark. I suppose that could equate to 3/4 of the way up. What outputs of the mixer and what inputs of the interface are you using?
 
With properly matched hardware you should be able to have the channel and master faders on or near the 0 mark. I suppose that could equate to 3/4 of the way up. What outputs of the mixer and what inputs of the interface are you using?

The ZED14 has 4 Aux outs. I have a balanced cable from the Aux 1/2 outs to inputs 1/2 of my Focusrite Saffire which only has 2 inputs. Aux 1/2 are pre-fader so as far as I know it's only the channel and master Aux 1/2 levels (after channel gain) that are controlling interface input level.

The 3/4 position of channel and master Aux levels just happened to give me a level that matched the PFL. I could have maxed out the channel Aux levels and lowered the master.
 
On knobs marked 1-10 or the like, 7.5 (3/4 of the way up) or so is generally the default or "unity" position. I notice the master knobs have a 0 around that point and +6 at the top of the range. So that all seems to line up correctly.

At this point you could probably make those channel aux and aux master settings your default and just tweak the gain to get your recording level if you ever change the signal going into the mixer.
 
Yes I have that marking too. And that's the plan.

Do I aim to get everything up to that 0 level to ensure strong signal, even quiet instruments, then lower it in the DAW?

And at this point I am using my interface for both headphones and output to monitors, so recording via pre-fade leaves my faders kinda sitting there. I know some people listen to the interface outs via mixer while others only trust the interface.
 
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