Seeking clarification on Zoom R16 1/4" input jack in XLR combo plug: Balanced or not?
I have a very simple question regarding the Zoom R16 XLR combo input jacks.
The Zoom R16 documentation appears to state that when you use an XLR connection to the combo jack, it is a balanced signal. The documentation is not so clear on whether the 1/4" port provides a balanced TRS connection. If I could find a schematic of the input bus for the R16, the answer would be easy to see.
I have seen conflicting info in a few forums regarding this, and I was hoping to find out for sure. Does anyone know the answer to the question? Or (better yet) is there a schematic out there that someone can share?
Thanks in advance for any assistance :-) Quesne
These are the only descriptions I see of the input ports from the user manual:
XLR/standard phone combo jack x8
(Balanced input) 1K balanced, 2 hot
(Unbalanced input) 50K unbalanced
1 equipped with Hi-Z switch, input impedance 470k (Hi-Z on)
2 equipped with phantom power switches
Input level: –50dBm
Supports input from a variety of sources, including guitars, mics and line level instruments. The 8 onboard jacks, which accept XLR and standard phone plugs, include one high-impedance input and two with 48V phantom power. From high-impedance guitars and basses to dynamic and condenser microphones and line-level devices like synthesizers, many sources are supported.
Why not plug a jack in and stick a meter on it? Tip to sleeve should be the same as ring to sleeve if it's balanced. If the ring to sleeve is a short, then its unbalanced. I'd bet it's unbalanced.
Thanks very much. When you say "Tip to sleeve should be the same", what exact units am I measuring? Voltage while powered on? Ohms? Continuity?
Please clarify and I will test. Thanks :-)
Ohms - that's what you are after. Expect a dead short!
Test with Zoom power off. If the ring-to-sleeve meter reading is zero (short circuit) or infinite (open circuit), the input is unbalanced. Only if it's the same as tip-to-sleeve is it balanced.
Thank you very much for the info, paulears and Boswell. I just made the recommended measurements on a balanced cable. It was plugged into the channel 8 input of my unpowered Zoom R16. Here are the results. I would appreciate help in interpreting the results:
On 2000K ohm setting
T - R = 92
T - S = 47
R - S = 44
On 200K ohm setting
T - R = 91.9 (slowly and consistently rises approx 0.1 per second)
T - S = 47.0 (stable)
R - S = 43.7 (slowly and consistently rises approx 0.1 per second)
On 20K ohm setting (or lower)
T - R = infinite
T - S = infinite
R - S = infinite
Just adding a quick note: I found this article from 2011 that seems to refer to the 1/4" inputs on the Zoom R16 as balanced TRS. I don't know much about the reliability of the source, but I thought it was worth posting here for any other folks searching for similar relevant info :-)
Balanced then! Useful to know - probably a simple balanced pad, so a mono plug into it just shorts the ring to sleeve, which nobody would be aware of.
A couple more pieces of info for the interested....
As per gecko zzed on the homerecording.com forum, the Zoom site shows the R16 specifications here:
Type: XLR/TRS combo jacks
Also, I found this on page 11 of the operation manual: "You can connect cables with XLR and monaural phone plugs (balanced or
unbalanced) to the INPUT jacks."
That also seems to indicate that the 1/4" connection supports a balanced connection.