[sdiy] Combined output / headphone jack?

[brianw]

The Ensoniq SQ-80 is far too old to support balanced TRS. On that model, the headphones would be stereo unbalanced, and the line output would be unbalanced TS connections.

In fact, it's still quite rare today (or so it seems) to find a synth that supports balanced outputs, but I agree that it's worth pursuing. I seem to recall that the Roland Jupiter-6 has balanced outputs, but they're on XLR male jacks, not TRS.

How many modern synths have balanced outputs? I think the Access Virus might. Which of those have TRS jacks for dual-purpose line outputs and headphone outputs?

For balanced, Tip and Ring are opposite polarity. For headphones, that would sound awful. I suspect that there would need to be some sort of manual switch to flip to stereo (unbalanced) for headphones or mono balanced otherwise. The challenge is that there is no way to automatically detect the difference between a headphone plug and a TRS balanced plug.

Brian

p.s. Re-reading your message, I realize that you probably don't expect the SQ-80 to properly support a balanced TRS plug that gets inserted, but you're wondering how that would be "handled." I would expect that the signal would be very faint on the other end of the cable, if it's actually connected to a balanced input. The faint signal would occur for sounds panned to center, and they would get louder as the sounds are panned away from center, but would still be as much as 6 dB quieter than a proper balanced signal.


On Oct 14, 2024, at 1:00 PM, Mattias Rickardsson wrote:
> Interesting topic!
> 
> The Ensoniq SQ-80 also has the two jacks labeled
> Left/Phones 
> Right/Mono.
> 
> Haven't checked the schematics yet, but I'd be most curious how they handle a balanced TRS plug or two.
> 
> /mr
> 
> Den mån 14 okt. 2024 21:44Andy Lambert skrev:
>> The Prophet VS does this. The Left jack is Left/Phones and the Right jack is Right/Mono. I haven't looked into the implementation but the schematics are widely available.
>> 
>> On Mon, Oct 14, 2024, 12:32 PM Neil Harper wrote:
>>> hey everyone,
>>> 
>>> just wondering if anyone is familiar with any synths that have a
>>> combined line-out / headphone-out 1/4" jack?
>>> 
>>> thinking about implementing it in a diy project and hoping to find some
>>> schematics where it's done properly. also wondering how it would handle
>>> the line-out mode where a TS plug gets plugged into the TRS jack and the
>>> headphone driven R just gets shorted to S.
>>> --
>>> /// Neil Harper
>>> /// Every Wave is New Until it Breaks
>>