Focusrite Scarlett - Why Are Headphone Outputs Tied to Particular Hardware Outputs?

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Focusrite Scarlett - Why Are Headphone Outputs Tied to Particular Hardware Outputs?

Post by ITHertz »

Hi Folks,

This is probably a question for Focusrite but I was thinking that some of the more technical people here might know the answer.

I currently use a Focusrite Scarlett (18i20) as my main audio interface and I'm very happy with it. However, it has one "feature" that puzzles me. From the manual:

The headphone outputs always carry the signals that are currently routed to analogue outputs 7/8 and 9/10 (as stereo pairs) in Focusrite Control.

Why would this be the case? Wouldn't it have been better if the headphone outputs were "free" of any particular analog outputs? That is, the headphone outputs would appear as just another output.

Cheers,

Chris
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Re: Focusrite Scarlett - Why Are Headphone Outputs Tied to Particular Hardware Outputs?

Post by Eddy Deegan »

It's relevant to me that you raise this as I bought my wife a Focusrite 18i8 recently for her birthday (she's getting into recording) and this weekend I'll be setting it up for her.

If I'm reading this Focusrite support link right then you can set up a custom mix for the headphones to deliver.

I've yet to delve into it but will be doing so over the next couple of days. This might be a response that is a bit "check this link for more info" and a bit "I'm hoping for some enlightenment from others myself" but I do know that a number of folk on the forum use Focusrite interfaces so hopefully someone can inject a bit of wisdom in the meantime.

Failing that, I'll share what I discover over the weekend :)

[Edit: I haven't read the manual yet]
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Re: Focusrite Scarlett - Why Are Headphone Outputs Tied to Particular Hardware Outputs?

Post by ITHertz »

I've sent the question to Focusrite too - I'll post the response here.
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Re: Focusrite Scarlett - Why Are Headphone Outputs Tied to Particular Hardware Outputs?

Post by Wonks »

If you look at the block diagram in the manual (which is poorly drawn IMO), you’ll see that one headphone output is driven from the output channel 7 & 8 hardware outputs and the other from the channel 9 & 10 hardware outputs.

Making them freely assignable would have involved four more D/A converters and associated support circuitry, which would also increase processor load; which may even have required a faster processor or else have had a hit on the latency figures.

It would certainly have put the unit cost up, and even small component cost increases can have a big effect on the sales price with all the mark-ups then applied. The product will have been built to meet a price point, so at some point in the design process, someone/some committee will have decided that it was a compromise worth making.

The Focusrite help article states the fixed hardware links mentioned above, and is about creating specific mixes in the routing software from given inputs to those output pairs. You can’t change the hardwired headphone output connections.

You can of course use an external headphone amp wired to a pair of line outputs of your choice, but you’ll still be tied to a particular set of hardware outputs, which in theory is no different to what you have now, just a bit more flexible if you have the outputs run to a patch bay.
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Re: Focusrite Scarlett - Why Are Headphone Outputs Tied to Particular Hardware Outputs?

Post by ITHertz »

Thanks Wonks, that makes sense.
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Re: Focusrite Scarlett - Why Are Headphone Outputs Tied to Particular Hardware Outputs?

Post by tomas »

You could also view it as having 6 line outputs, with 2 or 4 more available when you don’t need one or both of the headphone outputs.

Many (most?) other manufacturers use dedicated output channels for the headphone socket(s), which are not as easy to repurpose as line outs.

Invariably, all manufacturers will diligently count all channels of ADC and DAC in the specs of their audio interfaces, including those that are tied to ADAT, SPDIF.. etc. So, if it says 20 output channels and there are sockets for more than 20 channels, there’s some sharing going on.
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Re: Focusrite Scarlett - Why Are Headphone Outputs Tied to Particular Hardware Outputs?

Post by Little Boxes »

Hello everyone,
I am also the owner of a new Focusrite 18i20 & have been very busy navigating the both manuals as well as hands on usage.

After doing a multi track recording last night, I proceeded to play it back today but with no sound output from the A/I I was a bit stumped.

Eventually after altering different things I got it to work by changing a setting using the Focusrite Control in the input / output page. (Many hours)

I also have not been able to get sound from the headphones, either from the A/I or the Laptop. (Will try this later in the week).

Many thanks for the posted information.

Regards
Alan
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Re: Focusrite Scarlett - Why Are Headphone Outputs Tied to Particular Hardware Outputs?

Post by Ben Asaro »

This is not entirely accurate, as least as far as the 18i20 is concerned.

Yes, in Mix Control, outputs 7/8 - 9/10 are assigned to the headphone jacks but they can easily be assigned as line outs as well if you need more than 8 outputs after using the SPDIF out and don’t want/have to use the ADAT output. As mentioned above, it would be impractical to have the physical DACs and amplifier circuits freely assignable.

I am using a pair of line outputs for my RNHP headphone amplifier and it is interesting to note that when you assign ANY line out as DAW 1 or DAW 2, it is also controlled via the front panel’s volume, DIM, and Mute. I currently have four sets of mix outs from my 18i20: the dedicated headphone outputs, the RNHP, and the monitor outputs. Very convenient for checking a mix on multiple monitor devices!
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Re: Focusrite Scarlett - Why Are Headphone Outputs Tied to Particular Hardware Outputs?

Post by Wonks »

Ben Asaro wrote: Sun Aug 01, 2021 12:33 pm This is not entirely accurate, as least as far as the 18i20 is concerned.

Yes, in Mix Control, outputs 7/8 - 9/10 are assigned to the headphone jacks but they can easily be assigned as line outs as well if you need more than 8 outputs after using the SPDIF out and don’t want/have to use the ADAT output. As mentioned above, it would be impractical to have the physical DACs and amplifier circuits freely assignable.

I think you are really talking about the Focusrite mix software, as the outputs 7/8 and 9/10 are always line outputs and have headphone outputs 1 and 2 electronically respectively tied to those outputs and their signals.

I don't know the Focusrite mix software but I'd assume that the default would be for outputs 7/8 and 9/10 to be sent the same mix as outputs 1/2, the default monitor outputs. To use outputs 7/8 and 9/10 as outputs in their own right, carrying signals that are different to the main monitor output, you'd have to configure the mix software to break the default connection.

The headphone outputs would still duplicate the 7/8 and 9/10 line output feeds, so you'd then lose the ability to monitor the main monitor mix on headphones from those outputs.

I suppose it would be possible to configure outputs 9/10 as the main monitor output, so at least one headphone output would always be able to monitor the main mix when using eight line outputs for other signals, but you then loose the ability to send those particular headphones a custom mix.

If you do use a lot of line outputs for sending signals to several outboard hardware processors or a summing mixer, it would be a good reason to get a separate monitor controller with its own headphone output(s) so you can monitor the main monitor mix if necessary. If not, such a monitor controller would still allow you to monitor the main mix on headphones, as well as having two sub-mixes available.
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