Marshall DSL1C Guitar Amplifier. Questions about emulated line output.

[deniall83]

Apologies if this is in the wrong place, but I wasn't sure where else to post.

I'm looking at getting a new guitar amplifier and I like the look and sound of the Marshall DSL1C. The amp has an emulated line out which Marshall have said is for headphones or an audio interface. I'm a bit confused about this because you usually don't plug headphones into line level outputs. Anyway, I asked Marshall about this and got the following responses from one of their engineers:

Is it a fixed voltage, or does it change with the volume knob?
The Volume will change through the Emulated Output as the controls are adjusted on the front of the amp.

What is the voltage of the output? Also, what is the output impedance?
The Emulated output is around Line Level and the Impedance is low.

If it's a line level output, would it be safe for sensitive headphones or would I need to plug it into an external headphone amplifier?
The Emulated Output is designed for use of headphones for ‘silent recording’ etc. So yes, that’s fine. If you find that the signal through headphones isn’t loud enough, a headphone amp should help bring the level up for you.

I'm still confused by these answers. If the output is line level, why would the volume change with the control knob?
Is a line level output really safe for headphones?
How would one correctly hook up a headphone amplifier? Turn guitar amp volume up a certain % and then adjust final volume with headphone amp?

Thanks for anyone that can help out.

 

[staticV3]

All that we know at this point is that:

A) the output is adjustable so can be brought down to safe levels for both your ears and headphones.

B) according to Marshall, the output is safe to use directly with headphones, so you're not liable.

Everything beyond that, we'd have to test ourselves using audio analyzers, volt meters, dummy loads, etc. (thanks, Marshall!)

If you want to ensure a good quality output to low impedance headphones, then using an external headphone Amp may be worth it.

Though you have nothing to lose from trying your headphones directly first.

 

[Multicore]

If the output is line level, why would the volume change with the control knob?

Presumabley because that's how it was designed: as a dual use output. There's enough difference in what "line level" means in input specs on various devices that it could make sense. But it's a bit suspicious, I admit, especially given it's a tube circuit.

Have you considered the modeling amps available? They are really good now! I have a Positive Grid Spark and am happy with it. The Yamaha THR amps are great too.

On a practice amp I wouldn't want to have to use a separate headphone amp because it's just a bit too fussy an arrangement. For practice with headphones only the Boss Waza Air is hard to beat. It sounds great once you set it up to your taste.

 

[deniall83]

Thanks guys, I appreciate the replies.

 

[L5730]

Look at laptops and many other devices. Headphone / Line out dual purpose 3.5mm TRS stereo jack is usually there (sometimes a mono mic input as well on the same connector 3.5mm TRRS).
It really isn't uncommon to have dual use line/headphone outputs. They are usually not that great for line out purposes (low voltage, expect 2 volt for normal line level) or aren't great for headphones due to high output impedance.

Whilst it is all valve/tube pre and power sections, that's an odd choice of 12AU7/ECC82 for a power valve. The lower gain/breakup version of a 12AX7/ECC83. It's not the usual EL34 'loud' power tube. I wonder if using what is usually a pre-amp tube in the power section makes for better suited line/headphone output.

It also said 'emulated line out', so I guess it's got some kind of passive speaker simulation on there ala Palmer, but probably nothing like the same calibre. Anything to not sound like a non-IR amp would be good. No speaker emulation sounds like hot fizz.

 

[Bob from Florida]

Look at laptops and many other devices. Headphone / Line out dual purpose 3.5mm TRS stereo jack is usually there (sometimes a mono mic input as well on the same connector 3.5mm TRRS).


Whilst it is all valve/tube pre and power sections, that's an odd choice of 12AU7/ECC82 for a power valve. The lower gain/breakup version of a 12AX7/ECC83. It's not the usual EL34 'loud' power tube. I wonder if using what is usually a pre-amp tube in the power section makes for better suited line/headphone output.

The 12AU7 is a much better choice for the output stage over the AX7. You can run a lot more current through the AU7 and running it push-pull through a small output transformer gives you the opportunity to get some saturated output transformer distortion at low power. Have not heard one but I bet it has some great overdrive tone at bedroom practice volumes. I built my own design 1/2 watt amp years ago with a self-split 6N1P driven by a 12AX7 - both halves providing gain and it rocked at low volumes. Marshall is using 2 12AX7's, so likely second tube does split phase to drive the output tube. Probably long tailed pair to get more output. Should be a fun little amp!

 

[dfuller]

I'm still confused by these answers. If the output is line level, why would the volume change with the control knob?

It's after the end of the preamp but before the power amp input, which includes the volume control. I'd have to pull up the schematic to show you, but...

The Emulated output is around Line Level and the Impedance is low.

"Low" is a relative thing. In a tube amp, that might be 100R.