DM4800 Line Level

[Juzz]

Hi Folks,

I'm getting some inconsistent levels when going balanced line in to DM4800. Any selection of channel on the DM is the same.

The chain is
+4db test tone to balanced line in RME (ADI8DS) - TDIF out to TDIF in to DM and signal reads -12db
Compared to +4db test tone to balanced line in DM4800 signal reads -26.6db.
That's 14.6db difference for the same input signal.

When using line in on the DM it shouldn't be necessary to use the preamp, should it?

Am I missing something here?

Any suggestions would be great.

Thanks,

Justin

 

[Arjan P]

You don't say which inputs you use on the DM, and whether these are selected to Line and where the Trim knobs are set. That can make all the difference.. And I have no idea what the RME is doing to the signal..

 

[Juzz]

Thanks for your reply. Sorry, I should have given more information. It's set to line input on the DM and no trim. (set to zero) Also, there is no digital trim on the DM either. The RME (ADI8DS) is a line-level A/D converter. There is no amplification of the sound going on.

I can't work out why there is such a difference in level between the two. Thoughts?

 

[Arjan P]

Is this behaviour consistent over all physical channels? I'm referring to the test tone directly into the DM, since IMO the RME complicates things a bit at this stage. What is actually your test signal device? Did you measure the voltage it outputs? I can't imagine a 30 dB difference - oh, and how did you measure (or read) the -26.6 dB value on the DM? I wouldn't know how to read such a precise value on it.

 

[Juzz]

Yes, it's the same across all physical channels. In fact, it's the same across all physical channels on my second DM4800 also. The test signal is from a Behringer cable tester. It's a fixed test tone that cannon be altered. I haven't checked the voltage. Why should that matter and why would that give different readings? I recorded the input of both channels into cubase to be precise and took my measurements from there. Yes the input channel is at 0db and no or inserts or trim from within cubase. I could also see that the input meter on the DM was displaying the same results. Any suggestions?

 

[Arjan P]

Mm, well I ask about the voltage level because +4 dB is an actual voltage that is presented at the input. I happen to also have the Behringer CT-100, and see what they say about 'Test Tone Mode' in the manual: "Please note that this mode is not intended to work as a voltage standard and that battery voltage will affect the test tone output level."
See here for the actual voltage levels: https://en.wikipedia.org/wiki/Line_level

 

[Juzz]

Thanks for your reply Arjan. I tried running a test 44Hz tone at -12dB from a cubase tone generator insert plug-in. I sent the tone out via AUX send 1 (set at 0dB) and returned it back into the DM line in 1 at zero trim and I get a -24dB reading. I can't figure this out.

Since you have the same Behringer test tone unit would you mind setting it at +4db and connecting to line in DM zero trim and see what reading you get?

 

[Arjan P]

I'll give it a try next time I'm in the studio (but i'll also measure the voltage from the CT-100 ).

 

[Juzz]

That would be great. Thanks!