How many times can we split a line level output before there is degradation?

[xevman]

So this is a question i've been pondering ever since I split the XLR output on my DX7s. I used a pair of xlr splitters to connect the xlr outs of the dac to both my studio monitors and my headphone amp. This is no problem as the DX7s would have high output impedance and downstream gear has low input impedance. There is no audible difference and the level doesn't even drop the slightest amount (on the amp having both connected at the same time on the same output rather than just the amp by itself). The question I'm curious to know is how many times can we split a line level output before there is a significant drop in output or any other form of signal degradation? or does it depend on the output impedance/input impedance of components.

 

[amirm]

I would depend on the combined input impedances of all the ones being driven.

 

[xevman]

I guess that would be a lot given most amplifiers have low input impedance from what I've seen.

 

[Krunok]

I guess that would be a lot given most amplifiers have low input impedance from what I've seen.

Yes, quite a lot, as modern DACs have output buffers which are capable of providing substantial cureent output.

 

[Wombat]

Yes, quite a lot, as modern DACs have output buffers which are capable of providing substantial cureent output.

Then, use Rin(load) > 10xRout(amp) as a rule of thumb as a minimum if drive current is sufficient.

 

[restorer-john]

Something to bear in mind is the non-linear distortion that can be caused when split signals are sent to multiple devices where some are on and others are off. Unbiased front ends can, and do create some wicked distortions on other devices.

I remember the first time I experienced that in the 1980s with multiple tape-outs to cassette decks, where some were powered off- significant distortion ensued.

You'd have to FR sweep a signal into the various devices to see if there are issues, particularly at the HF end from paralleling/splitting your signal.

 

[Wombat]

Something to bear in mind is the non-linear distortion that can be caused when split signals are sent to multiple devices where some are on and others are off. Unbiased front ends can, and do create some wicked distortions on other devices.

I remember the first time I experienced that in the 1980s with multiple tape-outs to cassette decks, where some were powered off- significant distortion ensued.

You'd have to FR sweep a signal into the various devices to see if there are issues, particularly at the HF end from paralleling/splitting your signal.

I guess it can be a suck-it-and see(hear) thing at little cost.

 

[Krunok]

I guess it can be a suck-it-and see(hear) thing at little cost.

Yup, many things have changed from 1980s so today's devices are a little safer in that regard.

 

[DonH56]

I guess that would be a lot given most amplifiers have low input impedance from what I've seen.

Typo: high input impedance, low output impedance.

I have seen preamps with output impedances ranging with very low (<1 ohm) to perhaps 1 k-ohm or so. Single-ended (unbalanced) power amp inputs I have seen tend to run in the 10 to 100 k-ohm range with input capacitance in the 10's of pF (though some are much higher). Cables tend to run 20~25 pF/foot.

Unfortunately my experience indicates the "off" problem John raised is still with us; often it is an input device that is effectively a diode to ground so once you exceed perhaps 0.5 Vpk it starts to turn on and clips the input signal around 07 Vpk or so. I was helping a friend who wanted to use separate 2-ch and HT components and ran into this last summer with brand new components. Not sure the brands, unfortunately, think it may have been Denon or Marantz AVR and an Yamaha integrated. Once we figured out the problem, installing a switch box fixed it, and I never tried to see which component was the culprit (or if they all were).