a balanced RNP

[willovercome]

i was reading that the RNP is electronically balanced inside the box. does that mean i don't have to use balanced 1/4 inch cables? can i just use regular unbalanced cables and still have a balanced output?

also, along the same lines. on my computer's hardware setup should i put the RNP at +4, -10 (or somewhere else)? what about the DMP-3?

thanks.

 

[jonathanl]

I would think so. I use balanced cables an my RNP. I don't think you can use unbalanced cables and still be balanced. Balanced generally means +4 (which is the level used by "professional" gear, or something like that)


According to the M-Audio webpage, the DMP3 works in the same way.

I hope this helps!

--Jonathan

 

[acorec]

i was reading that the RNP is electronically balanced inside the box. does that mean i don't have to use balanced 1/4 inch cables? can i just use regular unbalanced cables and still have a balanced output?

also, along the same lines. on my computer's hardware setup should i put the RNP at +4, -10 (or somewhere else)? what about the DMP-3?

thanks.

"Balanced" ins/outs means that there are 2 signal lines that go into/out of a differential amp. The differential amp only amplifys the DIFFERENCE between the two signals. If there is a "common" signal on BOTH lines, the difference between them is zero. Hence, 60Hz hum , which is present on both signal lines is cancelled. The balanced amp has much more headroom as well. You must use a balanced cable to carry the two independant signals to the amp. So, single ended amps have a signal input and ground. Balanced amps have two signals and ground. Balanced cables/amps don't "see" 48v phantom DC voltage because the DC voltage is on both signal lines and is not referenced to ground.

 

[sjjohnston]

i was reading that the RNP is electronically balanced inside the box. does that mean i don't have to use balanced 1/4 inch cables? can i just use regular unbalanced cables and still have a balanced output?

The inputs and outputs are two different things. The RNP will have a balanced output no matter what the input is. This is useful if you are connecting its balanced output to something with a balanced input. It doesn't matter if you're connecting it to something with an unbalanced input.

For the output to be balanced, you need to connect a TRS ("balanced") cable. If you connect a TS cable, you'll just short one leg of the balanced output to ground. Which is fine, and won't do any harm (in fact, it's what you want to do when you connect its output to something that doesn't have a balanced input). But you won't get the benefit of the balanced output.

If you're connecting a mic of any appreciable quality to the RNP's input with an XLR cable, you're connecting a balanced output to a balanced input.

also, along the same lines. on my computer's hardware setup should i put the RNP at +4, -10 (or somewhere else)? what about the DMP-3?

I'm not sure how you "put the RNP at +4" or -10. Adjust the gain until you get a signal level that the next box in line is happy with.

 

[acorec]

Re: Re: a balanced RNP

The inputs and outputs are two different things. The RNP will have a balanced output no matter what the input is. This is useful if you are connecting its balanced output to something with a balanced input. It doesn't matter if you're connecting it to something with an unbalanced input.

For the output to be balanced, you need to connect a TRS ("balanced") cable. If you connect a TS cable, you'll just short one leg of the balanced output to ground. Which is fine, and won't do any harm (in fact, it's what you want to do when you connect its output to something that doesn't have a balanced input). But you won't get the benefit of the balanced output.

If you're connecting a mic of any appreciable quality to the RNP's input with an XLR cable, you're connecting a balanced output to a balanced input.



I'm not sure how you "put the RNP at +4" or -10. Adjust the gain until you get a signal level that the next box in line is happy with.

The balanced output is +4 when you used a Balanced output cable. If you use a single ended output cable, the output is -10. You don't set anything. Balanced output just has ~2X the output voltage as unbalanced.

 

[acorec]

Active Balanced Output Circuits

The signal is sent to an op-amp and provides one phase of the balanced output signal; this signal
is then inverted with another op-amp to provide the other phase of the output signal. Because the load is driven from the two outputs, the maximum output voltage is double that of an unbalanced output. The outputs are taken through two resistors, each of which is half of the desired signal voltage.

 

[sjjohnston]

Re: Re: Re: a balanced RNP

... If you use a single ended output cable, the output is -10. You don't set anything. Balanced output just has ~2X the output voltage as unbalanced.

This is partly true (at least if the output you're talking about is "active" or "really" balanced), but: 2x the voltage is 6 dB. The difference between +4 and -10 is almost 12 dB.*


* Yes, it looks like it should be 14: they're referenced to different levels, but let's not go into that now.

 

[plexi]

Re: Re: Re: a balanced RNP

Huh??

Oh well........ You`re all wrong...


The RNC has unbalanced I/O and is +4

 

[jslator]

The RNC has unbalanced I/O and is +4

They were talking about the RNP. You're right that the RNC is unbalanced, but it has a nominal operating level of about 0dBu (not +4).

 

[acorec]

Here is some info for everyone in case you guys want to know:



0 dBu Preferred informal abbreviation for the official dB (0.775 V); a voltage reference point equal to 0.775 Vrms. [This reference originally was labeled dBv (lower-case) but was too often confused with dBV (upper-case), so it was changed to dBu (for unterminated).]

+4 dBu Standard pro audio voltage reference level equal to 1.23 Vrms.

0 dBV Preferred informal abbreviation for the official dB (1.0 V); a voltage reference point equal to 1.0 Vrms.

-10 dBV Standard voltage reference level for consumer and some pro audio use (e.g. TASCAM), equal to 0.316 Vrms. (Tip: RCA connectors are a good indicator of units operating at -10 dBV levels.)

0 dBm Preferred informal abbreviation of the official dB (mW); a power reference point equal to 1 milliwatt. To convert into an equivalent voltage level, the impedance must be specified. For example, 0 dBm into 600 ohms gives an equivalent voltage level of 0.775 V, or 0 dBu (see above); however, 0 dBm into 50 ohms, for instance, yields an equivalent voltage of 0.224 V -- something quite different. Since modern audio engineering is concerned with voltage levels, as opposed to power levels of yore, the convention of using a reference level of 0 dBm is obsolete. The reference levels of +4 dBu, or -10 dBV are the preferred units.

0 dBr An arbitrary reference level (r = re; or reference) that must be specified. For example, a signal-to-noise graph may be calibrated in dBr, where 0 dBr is specified to be equal to 1.23 Vrms (+4 dBu); commonly stated as "dB re +4," that is, "0 dBr is defined to be equal to +4 dBu."

0 dBFS A digital audio reference level equal to "Full Scale." Used in specifying A/D and D/A audio data converters. Full scale refers to the maximum peak voltage level possible before "digital clipping," or digital overload (see overs) of the data converter. The Full Scale value is fixed by the internal data converter design, and varies from model to model. [According to standards people, there's supposed to be a space between "dB" and "FS" -- yeah, right, like that's gonna happen.]

0 dBf Preferred informal abbreviation of the official dB (fW); a power reference point equal to 1 femtowatt, i.e., 10-15 watts.

Have Fun!

 

[sjjohnston]

And then there's dBs, which is referenced to Peter Holsapple, Chris Stamey and some other guys (and sometimes not Chris Stamey).

 

[plexi]

They were talking about the RNP. You're right that the RNC is unbalanced, but it has a nominal operating level of about 0dBu (not +4).

Gotta cut back on the booze apparently.......