Art HeadAmp 4 - different headphones

[garrettendi]

Moron question here but is it ok to use the Art HeadAmp 4 connecting different headphones of different impedances to each channel on the HeadAmp simultaneously?

The manual states:

Ideal for virtually any home or project studio, the HeadAmp4 easily adds additional headphone outputs to any mixer, computer audio interface, workstation, iPod, media player or laptop without creating any additional load on the existing headphone source. Capable of driving up to eight sets of headphones using a combination of 1/4-inch and 1/8-inch TRS connections, the HeadAmp4 can easily accommodate a variety of headphone models with varying impedances

So am I right in understanding that this supports varying impedances connected at the same time? Each channel has its own volume as well.

[Luke W]

As far as I understand, you will be completely fine, yes. With all the channel volumes set the same then levels will vary between cans, but nothing will explode

[garrettendi]

Thanks Luke, this will come in handy as my bassist, myself, and most likely our future drummer are all using different headphones (or in my case a wireless transmitter for my cochlear implant!).

[John Willett]

Moron question here but is it ok to use the Art HeadAmp 4 connecting different headphones of different impedances to each channel on the HeadAmp simultaneously?

The manual states:

Ideal for virtually any home or project studio, the HeadAmp4 easily adds additional headphone outputs to any mixer, computer audio interface, workstation, iPod, media player or laptop without creating any additional load on the existing headphone source. Capable of driving up to eight sets of headphones using a combination of 1/4-inch and 1/8-inch TRS connections, the HeadAmp4 can easily accommodate a variety of headphone models with varying impedances

So am I right in understanding that this supports varying impedances connected at the same time? Each channel has its own volume as well.

Personally I would use the HeadAMP 4 Pro as this has a separate amplifier for each pair of headphones, while the standard HeadAMP 4 has a single amplifier that all the headphones share. This means that impedance differences on the latter will load the circuit and alter the volume levels and load impedance.

[garrettendi]

I only have a HeadAmp 4 and cannot get the Pro.

I'm interested in what you say about the load impedance? The manual specifically states it doesn't put any additional load on the source

[garrettendi]

Additional: The circuit diagram in the manual suggests that each channel has it's own amplifier?

EDIT: I think I misread the diagram. It might not be amplifiers

[garrettendi]

Sorry for the spam. These are the specs from the manual:

Maximum Input Level:+14dBu
Input Impedance:90.9k Ohms
Maximum Output Level:+14dBu
Maximum Gain:20dB
Output Impedance: 47 Ohms (each output)

As you can see, the input impedance is always 90.0kOhms

[John Willett]

Sorry for the spam. These are the specs from the manual:

Maximum Input Level:+14dBu
Input Impedance:90.9k Ohms
Maximum Output Level:+14dBu
Maximum Gain:20dB
Output Impedance: 47 Ohms (each output)

As you can see, the input impedance is always 90.0kOhms

The HeadAMP 4 (or HweadAmp4 according to the manual ) actually looks like it does have four separate amplifiers according to the flow chart in the Owners Manual - but, be aware, that the ¼" socket and the 3.5mm socket for each output are wired in parallel. This means that plugging in two headphones of different impedances into the same output will affect the level - low impedance headphones being louder than the high impedance ones.

I would personally treat this as a 4-channel unit, rather than an 8 and only use one pair of headphones on each output.

[garrettendi]

Agreed on the 8 channel point.

So I'll use a maximum of 4 channels at once, I won't double up on the channels, and I'll feel safe to use different impedances, as long as it's one per channel!

Thanks all!

[James Perrett]

Additional: The circuit diagram in the manual suggests that each channel has it's own amplifier?

EDIT: I think I misread the diagram. It might not be amplifiers

I'd agree that the manual shows separate variable gain amplifiers for each pair of outputs. However, the 1/4" and 1/8" outputs on each output share the same amplifier. If the volume controls were at headphone level they would probably need to be more expensive wirewound types so it would make sense to me to use separate amplifiers after each volume control.

However, even if they were to use a single amplifier, putting 100 ohm resistors in series with each output would have the effect of isolating the outputs from the effects of using different impedance headphones. This is what I did with the old studio headphone boxes which were driven from the speaker outputs of a hifi amp.

[garrettendi]

I think I understand what you're saying James,

Different impedances on the 4 channels (one per channel) are safe, but not on the two parallel inputs.

[John Willett]

[
I'd agree that the manual shows separate variable gain amplifiers for each pair of outputs. However, the 1/4" and 1/8" outputs on each output share the same amplifier.

That's what I said.