How to connect Headphone to Speaker Taps

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viggen

How to connect Headphone to Speaker Taps
« on: 8 Jan 2017, 08:01 pm »
I got a spare desktop tube amp (APPJ) that I'd like to hook up headphones to the speaker taps.  I recall seeing some boxes selling on ebay that has speaker line inputs on the back and a headphone output on the front.  I cannot find anything like that anymore.

Is there anything like that on the market?

FullRangeMan

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Re: How to connect Headphone to Speaker Taps
« Reply #1 on: 8 Jan 2017, 08:30 pm »
Adapter plug.

Armaegis

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Re: How to connect Headphone to Speaker Taps
« Reply #2 on: 8 Jan 2017, 08:44 pm »
Two important questions first:
Are your headphones wired up with a 4-pin XLR?
Does your tube amp have a shared ground on the negative terminals?

viggen

Re: How to connect Headphone to Speaker Taps
« Reply #3 on: 9 Jan 2017, 08:12 am »
Headphone will most likely be 3.5mm.  And, amp only has banana out.  1 black and 3 red for each channel so, yes, ground is shared.

FullRangeMan

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Re: How to connect Headphone to Speaker Taps
« Reply #4 on: 9 Jan 2017, 02:38 pm »
Usually speakers amps are too noisy for a good hp, sound will be compromissed.

Armaegis

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Re: How to connect Headphone to Speaker Taps
« Reply #5 on: 10 Jan 2017, 07:44 am »
Ok wait, there's 3 red taps per 1 black? ok so this is a transformer or autoformer coupled tube amp then. There's extra considerations that must take place. And no, that's not a guarantee that the output blacks have a shared common ground; you'd have to doublecheck with a multimeter.

In this scenario though, the best thing to do is reterminate your headphone to a 4-pin XLR "balanced" configuration and keep left and right completely separate. You will also want to to slap a resistor across the outputs to protect the amp. Really, something like this is the simplest boxed solution:
http://hifiman.com/products/detail/84

viggen

Re: How to connect Headphone to Speaker Taps
« Reply #6 on: 11 Jan 2017, 03:21 pm »
Thanks that's what I am looking for but was hoping for TRS input instead of XLR for flexibility.  But, perhaps I can get a headphone with detachable cables.

Armaegis

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Re: How to connect Headphone to Speaker Taps
« Reply #7 on: 11 Jan 2017, 05:48 pm »
Unless you know with absolute certainty that your amp's negative terminals are a shared ground, you should never connect a TRS jack to your amplifier. Connecting a 3-pole device to a potentially 4-pole device is a recipe for magic smoke.

FullRangeMan

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Re: How to connect Headphone to Speaker Taps
« Reply #8 on: 12 Jan 2017, 10:14 am »
Also some output amp circuits cant be bridged.

orientalexpress

Re: How to connect Headphone to Speaker Taps
« Reply #9 on: 12 Jan 2017, 03:28 pm »
Ok wait, there's 3 red taps per 1 black? ok so this is a transformer or autoformer coupled tube amp then. There's extra considerations that must take place. And no, that's not a guarantee that the output blacks have a shared common ground; you'd have to doublecheck with a multimeter.

In this scenario though, the best thing to do is reterminate your headphone to a 4-pin XLR "balanced" configuration and keep left and right completely separate. You will also want to to slap a resistor across the outputs to protect the amp. Really, something like this is the simplest boxed solution:
http://hifiman.com/products/detail/84
those 3 red taps mean for loading at 16 ohm ,8 ohm and 4 ohm .



roscoeiii

Re: How to connect Headphone to Speaker Taps
« Reply #12 on: 16 Jan 2017, 04:16 pm »


In this scenario though, the best thing to do is reterminate your headphone to a 4-pin XLR "balanced" configuration and keep left and right completely separate. You will also want to to slap a resistor across the outputs to protect the amp. Really, something like this is the simplest boxed solution:
http://hifiman.com/products/detail/84

I've used this box with good success with my MiniWatt amp (very similar if not identical to your APPJ amp). Great pairing for the hard to drive HE-5LE from HiFiMan.


Armaegis

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Re: How to connect Headphone to Speaker Taps
« Reply #14 on: 16 Jan 2017, 07:15 pm »
Even with the DIY version, do not build it unless you know with absolute certainty that your amp's negative terminals are a shared ground.

These converter boxes are basically just L-pads that merge the negative terminals together. Be aware that this will also potentially pooch your output impedance. Depending on your headphone, this can affect the frequency response.

edit: for all the hooplah, you can also just buy a proper headphone amp for cheaper than a converter box

FullRangeMan

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Re: How to connect Headphone to Speaker Taps
« Reply #15 on: 16 Jan 2017, 07:24 pm »
+1. HP works in the few miliVolts range, some speakers amps volume pots dont have the fine mV tuning need for a hp.