Wiring for headphones only

[Loquah]

Hi all,

I'm building a SEX kit soon and noticed in the manual that it recommends wiring for 32ohms (from memory) if using exclusively with headphones. Can anyone explain to me what impact this has in terms of output impedance and why the 32ohm wiring is recommended? I.e. is it to maximise power output to high impedance cans?

For context, I have a Crack to drive my 600ohm Beyers so I'm looking at the SEX as a more versatile low impedance amp.

[Paul Birkeland]

Using the 32 Ohm tap provides the most output power for headphones.  This tap works nicely with medium impedance inefficient headphones (think orthodynamic).  If you plan to just use low impedance headphones, I would set the amp and 4 or 8 Ohms and leave it alone, as you won't need the additional power that the 32 Ohm tap provides, and the lower impedance taps will have a bit better signal to noise ration.

-PB

[Loquah]

Perfect. Thankyou!

[Loquah]

Using the 32 Ohm tap provides the most output power for headphones.  This tap works nicely with medium impedance inefficient headphones (think orthodynamic).  If you plan to just use low impedance headphones, I would set the amp and 4 or 8 Ohms and leave it alone, as you won't need the additional power that the 32 Ohm tap provides, and the lower impedance taps will have a bit better signal to noise ration.

-PB

I've just been doing a review over on Head-Fi and noticed on the website that it says the 32ohm setup has a very low noise floor. Does that mean that I'm better off wiring for 32ohm if not using speakers? I wired it originally as 8ohm so I could test speakers with it and it has an obvious hum when there's no audio input signal so I'm wondering if changing to 32ohm might fix this.

[Grainger49]

I'm not familiar with the SEX output transformer.  If it is a standard output transformer I think you can wire the headphones for 32 Ohms and the speaker outputs fed from the 8 Ohm tap.

[Loquah]

That could be good.

What benefits would be gained wiring the headphones from the 32ohm tap?

[Grainger49]

I don't know if you get a benefit with the 32 Ohm headphone tap.  Only that it seems feasible.

[Loquah]

OK, thanks Grainger.

Can anyone confirm if A) it's feasible and B) how it's of benefit?

[Doc B.]

Lower impedance tap = lower noise floor.  No need to use 32 ohms unless you can't get enough juice from a lower impedance tap.

[Paul Birkeland]

I've just been doing a review over on Head-Fi and noticed on the website that it says the 32ohm setup has a very low noise floor.

The lowest noise floor will be present on the 4 Ohm setting.

[Loquah]

Ok, great. Thanks everyone. I'll leave it as is

[Lar]

Just a quick question, can the SEX be wired up for balanced headphone connection? XLR?

[Paul Birkeland]

Just a quick question, can the SEX be wired up for balanced headphone connection? XLR?

Yes.  This is most easily done by installing the impedance switch kit, then making a speaker cable to 4-pin XLR cable to interface with the SEX.

[Lar]

Thanks, good to know.