Impedance matching audio circuit

[dcarver]

StarComm audio amp has output impedance (Z) of 32 ohms.

Etymotic ER6 is 48 ohms (and are discontinued)

Etymotic ER6i is 16 ohms and caused amp thermal run away. and is also discontinued.

Replacement for ER6i is hf5 (my selection, like balanced armature sound over moving coil) and Z = 16 Ohms.

OK, no I'm off to find some way of matching these imbalanced impedances. From Wiki I find a circuit that looks promising and easy to build -

where Ra =

and Rb =

Given that

Z1 = 50 Ohms (stated that Z1 must be > of two Z's)

Z2 = 16 Ohms

I think I calculate correctly that

Rb = 19.4 Ohms

Ra = 41.2 Ohms

Does this look correct?

Is there a simpler solution?

Should I be using another technique e.g. circuit design type?

(Man, it's been a loooooong time since I played elec tech... )

Thanks in Advance,

dcarver

 

[FJRay]

It's all greek to me but when you figure it out you can fix mine so it still works when hot.

 

[Bike Effects]

We have been down this road before My Friend Let me know what you find out, please.

 

[allrider]

If you're impotent i don't think that formula will help.

 

[mcatrophy]

Without checking your sums (they do look about right), do you actually need to impedance match?

A resistive impedance matching pad such as this will prevent reflections, but will reduce power transfer considerably.

I suspect you would do better simply to put a 16 ohm resistor in series to make the 16 ohms of the earpiece up to 32 (assuming 32 is sufficient to prevent the thermal run-away), this will give the maximum power into the earpiece albeit with a little resonant distortion, the amount of distortion depending on all sorts of factors, but probably you won't notice the difference whilst riding a motorcycle.

 

[HotRodZilla]

Jesus Carver...Get a girlfriend!

 

[Bluestreek]

Its all geek to me too. :dntknw:

 

[spike747]

Wow, I'm an electronic engineer and even I thinlk this is a geeky thread. But I may have had to much to much buy ju tonight. Too much thinking and not e4nough ridnbg..

 

[dcarver]

Wow, I'm an electronic engineer and even I thinlk this is a geeky thread. But I may have had to much to much buy ju tonight. Too much thinking and not e4nough ridnbg..

LOL, yep!

But will the circuit work as intended?

 

[Khunajawdge]

Hi Don -

Don't know how to answer your above diagnosis of your current audio problem? I can only add my experience with audio here.

I have an apparently now obsolete Monster Amp (https://webpages.charter.net/bpeloquin/Monster-Amp.html) which was designed for Collett's Bass Monster Speakers originally sold through Aerostitch Wearhouse. I use an IPOD Shuffle for sounds and an Escort X850 radar detector which has priority over the sounds. Recently within the last 2 years, I switched to a pair of ear plug speakers that I got from the now closed Central Coast Mechanics Shop on South Higuera St. in SLO. After switching to the ear plug speakers which were explained as a high quality pair of hearing aid speakers(?), the amp now occillates with a repeating squelch that is damn hard on my ears, so I quit using it for sound. I'm interested in what you are trying to do with your thread and will stay tuned here for what you find out.

In the meanwhile, have been considering one of these; https://www.mixitproducts.com/