#13

@deru sorry for the delay— i just did some scope measurements and they suggest that norns is actually closer to +4dBu:

  • outputting a test sine at max volume i see 3.2vpp
  • patching that back into the input it the norns VU shows about 90%

what specific gear have you been using that has required level adjustment?

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DIY: norns shield
#14

Oh really? Interesting thanks…

I hook it up to my UAD Apollo’s and I find that I need to activate the -10 input setting (vs +4) and turn it up a dB or two to get the gain comparable to my other studio gear. It’s obviously not scientific but that’s what made me ask the question to begin with.

#15

It might be that it is dependent on the app and what engine levels are set at.

For example, I had to set the polysub note levels on the m18s script i made pretty low because there was some internal clipping when I had the two synth lines going with a lot of release on the notes. even -10v on my apollo is not quite enough to bring it up…I have to put a preamp in the insert that gains the signal a bit more. Doesn’t seem to introduce any noise floor or other bad artifacts to the sound tho

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#16

in all cases, make sure in-the-box level settings are approparite.

for hottest output, make sure master output and engine levels are up.

for input: be aware that e.g. MLR sums L+R inputs to each channel. (other softcut-based scripts likely do this as well.)

my measurements in the past have been similar to @tehn’s, with max output peaking at around 1.5 Vp, so ~1 V RMS for a sinusoid.

which is something like 0 dBu, not -10 dBV.

(be aware when looking at reference numbers of the difference between peak / peak-to-peak / RMS, difference between dBv and dBu reference points (and load assumptions,) and the fact that conversion between these units requires knowledge of the signal shape - hence the standard of comparing sinusoids.)

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#17

I always have a doubt that torments me😌
I’d like to ask a questions about how to set up routing in a live set using Fates.

Considering that it should not be a good thing to mix line signals with modular signals, I wanted to understand if I use my ER-301 as a normal mixer connecting for example:

2ch out from morphagene to 301
2ch from Intellijel uVCA where are routed two VCO voice to 301
2ch from FATES to 301
(whereas I would use a limiter or gain from the simple mixer channel of the 301 to bring FATES to an acceptable level)

I would risk problems with the Fates audio codec?
I would be happy if someone would help me understand.

Thanks

#18

You will have no problems with that setup. The ER-301 has analog preamp settings for IN 1-4 so you can bring your Fates up to nearly modular level. I recommend that before patching internal (digital) gain so you get a better signal:noise ratio.

Be cautious with ER-301 modular level outputs to line level gear so you don’t damage your hearing. Even if you put attenuating units on every output, the sample preview functions will play at full volume. Brian at O|D has promised a universal output attenuation setting in a future update.

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#19

Thanks:)
the final signal (mixdown) from ER-301 then goes into a Magneto and then into a zdsp where I have the dry controls so I shouldn’t have problems with the volume too high.

#20

i woud not recommend running modular signals directly into Fates inputs.

Fates uses this codec, which is not rated for input voltages of >5v or so

since the Fates schematics are not published, it is not easy for me to characterize any voltage scaling or limiting that is happening before input audio hits ADC pins, so can only make conservative recommendations.

you can of course measure levels coming onto the board, and compare them with levels at the ADC pins, to make your own determination.

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#21

Thanks for the answer
I would never send signals from the modular not properly attenuated. my doubt was whether the route of other modular signals inside the ER-301 together with the FATES Outs could be some return signal.

in this configuration I only use the Fates’s OUTs

#22

Thanks for chiming in. For reference - the schematic is pretty much the same as the sample “RECOMMENDED EXTERNAL COMPONENTS” section of the data sheet on page 60.

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#23

Apologies in advance if this is off-topic – but I made the mistake yesterday of plugging my modulars outputs into Norns’ outputs (and monitored via headphones). I really need to add some labels on there, as I always assume the outputs would be next to the headphones :slight_smile:

Anyways, what’s surprising is that you still get audio out, it’s just got a crazy amount of FM and distortion. I really thought my Mangrove, Cold Mac, or RIP was broken, but after removing variables one by one, I finally realized I had plugged into the wrong jacks.

Everything is fine now, but out of sheer curiosity… does anyone know how is that possible? And where is the FM was coming from?

#24

oh! wild.

stock norns? they are.

image
image1397×924 16.6 KB

curious what’s happening :slight_smile:

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#25

Oh boy – yes, stock Norns. I might need to do some debugging tonight then. I’m getting a clean signal through my outputs but a terrible signal through my inputs?!

#26

@xeric Could the incoming signal be too hot possibly? An unattenuated euro signal may be something to look at. Just a shot in the dark. Good luck!

#27

Don’t think so – it’s going through RIP which should bring it down to line level.
Nothings changed in my setup recently

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#28

Ahhh damn. Well hope you get it squared away. Everything else in the Norns world id deeper waters for me :wink:

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#29

Question for those with a bit more electrical knowledge than me:

For attenuating modular levels for input into norns, could you use a voltage divider on the modular signal to bring it down to line level?

If I’m correct in this:
Vout = Vin * (R2 / R1 + R2)

Vin: 5v (10v peak to peak)
R1: 2200Ω
R2: 1000Ω

Vout = 1.56v (3.12v peak to peak?)

This would be a super simple thing to build into a cable or a small box or 2 HP module.

Not sure how this would affect audio quality, but would love input from folks who know more than I do.

I’ve always been a bit mystified by Line vs Modular vs Headphone vs Mic levels…

#30

A transformer is more appropriate.

#31

Sure, do you have any technical info you could share on this?
I understand this is what RIP & others do, but I don’t have transformers sitting on my bench atm :wink:

#32

I like this site. It has some great audio circuit examples with the math behind them.

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