Sound Devices mixpre to h4n

[Blackout]

I am thinking a little trick would be to take the great headphone out from the sound devices mixpre, and use a 1/4 stereo to two mono 1/4 cables, and run that into the h4n line in and then you could use the mixpre headphone jack to attenuate the line signal, and you could plug your sony v6 headphones into the zoom h4n to monitor the recording.

This should solve the no line in on xlr problem and save tons of money. The h4ns preamps ae crappy but the DAC is more than adequate.

What do you think?

 

[Alex H.]

I think that taking the headphone signal from any sound mixer as a recording output is a big no-no.

You're better off getting some in-line attenuators (pads).

 

[Gohanto]

I do basically that, but I just run the "Tape Out" from the MixPre into the 1/8" external mic-in on the back of the H4n. Using the mic pots to adjust the levels. (the headphone output isn't designed to be as high quality as the Tape-Out or Line-Out)

Now, that said, the MixPre limiters kick in at +18dBu with factory settings. The H4n clips at +18dBu, which basically means if you hit the MixPre limiters, the signals already clipped. You can adjust the MixPre limiters down, but it's a pain and it's almost impossible to do so accurately.

I just tried running the signal through MixPre headphone jack into the H4n line-in to see if that solves the problem, but it doesn't really. The headphone pots don't have linear gain/attenuation.

So, if you don't need limiters in your work, just grab a 1/8" cable, and go Tape-Out (MixPre) to Ext-Mic in (H4n). If you do need limiters, play with the MixPre limiters. Or find a device that'll allow you to record at least +20dBu without clipping (PMD661 allows this, more expensive, although I'm sure there are other recorders that work with this)

One other note, although Zoom released a firmware update for the H4n that allows you to set a recording level of "0.1" through "0.9", don't use them. If you clip the H4n with the level set to "1" then you're clipping the DAC.

 

[Steve House]

I am thinking a little trick would be to take the great headphone out from the sound devices mixpre, and use a 1/4 stereo to two mono 1/4 cables, and run that into the h4n line in and then you could use the mixpre headphone jack to attenuate the line signal, and you could plug your sony v6 headphones into the zoom h4n to monitor the recording.

This should solve the no line in on xlr problem and save tons of money. The h4ns preamps ae crappy but the DAC is more than adequate.

What do you think?

Why do you want to kludge it like that? Using the headphone output presents a real risk of overdriving the recorder inputs and clipping at the input. What about a pair of simple cables with an XLR-F on one end and a TS plug on the other? Sound Devices says to connect the MixPre main outs to unbalanced inputs, simply leave output pin 3 unconnected, so wire 'em XLR pin 2 to tip, XLR pin 1 to sleeve, XLR pin 3 floating. MixPre main outs to H4n Line In. If the problem people are running into is finding the MixPre output too hot, floating pin 3 reduces the level by 6dB. Problem solved.

 

[Glen Trew]

A little info about using headphone outputs as a line level source:

There's not necessarily anything wrong with using a headphone output to feed a line level input. In addition, there is no particular likelihood of overdriving a line level input with a headphone output.

Headphone amps are designed for low impedance loads in order to achieve adequate loudness in headphones without clipping (Sony 7506 headphones, for example, are about 70 ohms). The standard for line level inputs is 10K ohms or higher, so even though a headphone amp is capable of producing a lot of volume in a pair of headphones, it will not create the same wattage when driving a high impedance input designed for line level. Therefore, a headphone amp is not more likely than a line amp to overdrive a line level input.

Something to pay attention to, however, is gain structure. For example, last year we were getting complaints from customers about excessive noise when using the headphone output of the Sound Devices 788T to feed the return inputs of the 442 mixer (two high quality pieces of gear). It turned out that the customers were wanting to keep the return input levels at the same setting for camera headphone out as for the 788T headphone out, which required turning down the headphone amp of the 788T to about 9 0'clock (because the headphone amp of the 788T is much hotter than the puny headphone amp of a camcorder). This resulted in excessive noise in the monitor circuit because the 788T headphone level was turned way down, then reamplified, self-noise and all, at the return inputs. Keep in mind that this would have also happened if a line output was used.

With the above example in mind, I've found that when using a headphone output to drive a line input, the headphone volume control should usually be in about the same position as it is when using it to drive headphones (typically about 12 to 2 o'clock with mixers made for this industry).

Another important thing to keep in mind: Most headphone outputs are unbalanced stereo circuits. To use them to drive a line line input, the left and right outputs should be adapted to two unbalanced connectors (like an RCA or unbalanced XLR). If a stereo headphone output is treated like a balanced line signal, there could be 100% cancelation where nothing is heard.

All this may be a lot of technical hoo ha for many, but suffice it to say that a headphone output can successfully be used to drive a line input. There are a few things to be aware of such as gain structure and adapting the stereo headphone connector, but overload distortion is not one of them.

Glen Trew

 

[Steve House]

....
All this may be a lot of technical hoo ha for many, but suffice it to say that a headphone output can successfully be used to drive a line input. There are a few things to be aware of such as gain structure and adapting the stereo headphone connector, but overload distortion is not one of them.

Glen Trew

Thanks for the heads-up. I've always been leary of trying to send headphone outs to any input for years. The few times I tried it was just too easy to set the gain of the headphone amp beyond what the input could accept.

 

[Glen Trew]

Thanks for the heads-up. I've always been leary of trying to send headphone outs to any input for years. The few times I tried it was just too easy to set the gain of the headphone amp beyond what the input could accept.

While I can produce distortion using a Deva recorder headphone output with the volume knob turned fully up into a line input, but the distortion is not from overdriving the line input; it is from too much level within the headphone amp itself. This should not be confused as a weekness of the headphone circuit, because the same thing can occur in any output device trying to produce a signal hotter than it was designed for. When driving a line input, the headphone level should be in about the same position as it is when listening to that same output with headphones (typically 12-2 o'clock). You can also set the line input control at about the same position as it would be for other line output devices, then, using a line-up tone, bring up the headphone level until proper level at the input device is achieved. You should have a clean signal with ample headroom.

If anyone can produce overload distortion of a line input caused by the left or right channel of a commonly used professional portable mixer's headphone output, please post the details. I am currently unaware of any such overload issues, but if someone knows of such a configuration, I would like to determine what the actual cause is.

Glen Trew