[igotyofire]

I was curious how audio splitters work, but im not exactly talking about Y-cables. I was curious on how to split music with one music source, and amp to 2-3 headphones. From that point on do you split the amps output and put potentiometers to each audio output? so that each device can get the correct drive? I assume if one attempted this method you need a powerful amp turned up high?


or is it prefered to have one input & amp each output seperately? but drawback if one wanted to use it for testing out another amp so everyone could listen to it , then you would be amping the signal twice and not directly listening to the source amp.

 

[nikongod]

Quote:

Originally Posted by igotyofire /img/forum/go_quote.gif I was curious how audio splitters work, but im not exactly talking about Y-cables. I was curious on how to split music with one music source, and amp to 2-3 headphones. From that point on do you split the amps output and put potentiometers to each audio output? so that each device can get the correct drive? I assume if one attempted this method you need a powerful amp turned up high?

If everyone has the same headphones this works out OK assuming everyone likes the same levels and the amp can drive the combined load properly. Thats a lot of ifs so it seldom works. The headphones are in parallel, so a few sets of low impedance headphones may be too low of an impedance for the amp to drive well.

The problem with putting a volume control on the output of the amp is that the output impedance of the amp is conditional on where the pot is parked and generally quite high no mater what you do. Depending on the headphones it could be harmless or it could be pretty important. Its better just not to do it.
Quote:

or is it prefered to have one input & amp each output seperately? but drawback if one wanted to use it for testing out another amp so everyone could listen to it , then you would be amping the signal twice and not directly listening to the source amp.

Amplifying the signal twice is as you mentioned not ideal, but it may be the only way to get a consensus from a group. As long as you keep the variables to a minimum and the splitter amp is good enough to get the differences through you should be reasonably OK.

You can buy fairly inexpensive amplifiers designed for studio use like this. 1 input, and several headphone amps built in, each with its own volume control (before the amp) and every headphone gets its own actual amp. They are generally kind of cheap, but if you are trying to get a consensus of how a certain change to the circuit sounds from a bunch of people at once it may work. At least everyone is listening to the same amplification chain.

If you are testing a headphone/power amp this way be sure to load the output between the output of the "amp under test" and the "distribution amp(s)" with a realistic load. There are enough headphone amps that measure and sound great loaded with a high impedance (300 ohms or more) but measure and sound flat out ugly when loaded with 32 ohms that this is worth taking into account if you want to run 32 ohm headphones off of whatever it is you are testing. OTOH, if you are testing (as an example) the effect of changing something in the gain stage (cathode resistor/led/grid bias & plate resistor VS choke VS transistor CCS?) on a simple OTL tube amp it may be better to use a higher impedance so you are not listening "through" whatever crap the output stage does driving 32ohms.

FWIW, its been my experience that a 6dj8 white cathode follower is transparent enough into 32 ohms to hear differences in various tube loading&biasing methods, but YMMV and its still better into 300 ohms or more.

 

[glingrem]

There are special phone splitters, but professional, not audiofilic quality, for use in studios.
Its include one preamp and number (four or six) of separate volume regulators & power amps for every controlling channel.

 

[linuxworks]

buffer each channel and that's how its done (well).

passive is going to cause signal loss and is only good if its an internal y-cable and the lower signal will be accounted for.

generally, buffer each split signal. this applies to both digital and analog.

passive splitting 'works' but its not the proper solution.

 

[wavoman]

Indeed, most of the pro multi-headphone units (n headphones, each with its own dedicated amp and attenuator) are not audiophile quality.

I have researched this topic very, very carefully. The only unit off-the-shelf that seemed half-way decent from an SQ standpoint is the Clarity Headlite from DACS in the UK.

Clarity HeadLite 2 - Balanced Input

is the unit with balanced input -- they have an s.e. version too. As a bonus you get a 4-channel input selector.

But in the end I had mine custom built -- even that took a lot of research. I found, and used, QESLabs in Italy. My unit is shown on the QES Labs web site. The head engineer, Val, is great. My unit has balanced HP in, pass-thru, and power on the back, 2 independent balanced HP amps on the front, two stepped attenuators (all hand wired, all audiophile grade) in one nice 1U rack unit. For deatils see:

HPBA-2

I had it designed and voiced for beyer 600 ohm HPs, and use it today with 880/600s and 770/600s with great success.

 

[igotyofire]

well this topic sounds extremely complex & not likely somthing a DIY beginner could accomplish heh ive only built a cmoy

 

[amb]

If you're comfortable with the cmoy and happy with its sound, then it's really not that complicated. Basically, all you need to do is build a separate cmoy for each headphone output, each having its own volume pot at the common input. Depending on how many of them you build, the combined (parallel) volume pot's resistance should be kept high enough to avoid loading the source too much. For example, if you build a 5-cmoy amp, use a 50K pot for each so that the paralleled resistance is no lower than 10K.

 

[glingrem]

Quote:

Originally Posted by amb /img/forum/go_quote.gif For example, if you build a 5-cmoy amp, use a 50K pot for each so that the paralleled resistance is no lower than 10K.

Or build sixth cmoy and get it between the input and volume regulators, for example

 

[linuxworks]

get a mixer and run it backwards.

(I'm kidding)

then again, if you diy it, you could take a multichannel mixer and break the 'mix' point and separate the sections and make them individual amps. join them at the source and you've converted a mixer into a distro amp.