1. Home
  2. Electronics Design
  3. Connecting Headphones in Parallel With a Speaker

Connecting Headphones in Parallel With a Speaker

I would like to connect some headphones in parallel with a single speaker. The amplifier powering the speaker is a 110-W, Sony STR-DE997 A/V, surround-sound receiver. The speaker has an 8-ohm impedance. The headphones are Sennheiser model HD 580 (open air) with a nominal impedance of 300 ohms and a "load rating" of 200 mW.

I'm sort of guessing/figuring that a 3K-ohm resistor in series with the headphones ought to work. The 3K ohm resistor in parallel with the

8-ohm speaker would yield a net resistance of about 7.9 ohms to the amplifier. And if power divides the same way current does, that should provide a maximum of about 300 mW to the headphone. There would only be a signal to one side of the headphone, of course. I would also put a headphone volume control in the cord.

As anyone ever done anything like this before? Does anyone know of any reason it wouldn't work?

---------------------------------

The reason I want to do this, incidentally, is to try to clear up a problem that I have with hearing dialog in TV movies, etc. The headphone would be connected to the center speaker of my surround sound system. The center speaker typically carries the speech part of the audio, while the other speakers carry mostly the sound effects. The fact that I would only get sound in one ear probably wouldn't matter at all since one of my ears is really, really bad and the other one is only sort of bad.

Reply to
mg
Loading thread data ...

On a sunny day (Sun, 2 Dec 2007 23:21:01 -0800 (PST)) it happened mg wrote in :

It is better to use a circuit like this:

150 Ohm -- R1 ----------- from | amp R2 10 Ohm headphones | -----------------

We ant to drive the headphomes from a low impedance, that damps any resonances, so I will just use 10 Ohms for R2. Lets see, 110 W (if you amp can do it) in 8 Ohm, U^2 / 8 = 110, so U^ = 880, so Ueff = sqrt(880) = 30V.

1.5V is enough for big sound pressure on the Senheiser, so you divide by 20. 19 x 10 = 190, so with R2 10 Ohm, make R1 200 Ohm.

The max power in R1 is 30 x 30 / 150 = 900 / 200 = 4.5W The 'music' power is about 1.10 of that, so .5W Use a 5 W resistor if you are going to listen to 100% sine waves. Else use a 1W resistor..... (for R1).

The extra 4.5W will not be noticed much by your amp, especially as it is purely resistive.

Reply to
Jan Panteltje

I would have never guessed that the best way to do it is with two series resistors instead of simply using one, but then I don't know anything about audio. I did manage to find something off the shelf and it has the two-series resistors design. The only difference is that the second resistor is a potentiometer. So, I suppose if you went to the end of the adjustment, you would only have one resistor, but otherwise there would be two. I've decided to buy it. It's called the "ART HeadTap Headphone Tap" (#180628) and is described at:

formatting link
formatting link

Reply to
mg

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.