Has anyone used this to boost iPod volume?

[edweeks]

The audio volume from my iPod is lower than I like. I was thinking that the "Boosteroo" (http://www.boostaroo.com/) might do the trick. Has anybody used this product or have another idea? I have a PMA 8000 Audio panel and use Bose headphones.

Thanks,
Ed

[Guy Prevost]

If you do a search for "boostaroo", you'll get several hits. I was going to link them here for you, but there are quite a few posts to weed through.

Guy

[gmcjetpilot]

That little device would probably help, but reading the spec it has a 500 ohm impedance input and optimal output at 8 ohm impedance, its kind of backwards for your application, I think.

You are taking a 32 ohm impedance input (output from your iPod), going into the 500 ohm booster's input. The output from the booster (8 ohm), going into the 600-1000 ohm impedance intercom aux input. You really want the opposite. It will do something (may be), because the amplifier might makes up for the miss-match inefficiency. If the device has a low power preamp, it will not help. You can buy it, try it, use it, keep it or return it, if it does not work.

iPod's output only 0.75v. Line-out audio (non-amplified) are 2v to 5v on most audio, meaning the iPod is only made to drive tiny ear buds. When you have to crank any amp, including the iPod, quality goes down. Lots of built-in inefficiency (mis-match), plus a low output amp, means you have low volume and/or distortion.

May I suggest a passive, easier and cheaper way, that might fill the bill. I just wrote about this in the link below. The issue is impedance mis-match. The iPod is 32 ohms and your intercom is 600-1000 ohms. A mini audio matching transformer, matches the impedance (close enough). This boosts volume without adding any preamp. You can make your own or buy it commercially for $35. (SEE LINK BELOW) Some low end intercoms might still benefit from both matching transformer and a pre-amp, especially with an iPod.

http://www.vansairforce.com/communit...367#post196367

If you still want an pre-amp, a better mouse trap you might want to check out is this link. You can make one or buy it commercially.

http://www.minidisc.org/headbanger.html

Your PMA 8000 is stereo I assume. The PMA 8000 is top end unit and no doubt has a preamp in the aux input, so I think you will get more mileage out of the impedance matching. Some intercoms do suffer from not only impedance issues but a lack of pre-amplification. Still low output voltages from little devices (like iPods) is an issue. The miss-match just makes it worse. Call PS engineering and ask them.

Here is a TIP: Using the iPod's LINE OUT instead of the headphone jack gives better sound quality. You will need a preamp using the LINE OUT, which are not amplified at all. The headphone jack audio is running through the little internal amp, which lowers the sound quality. The line-out requires a car charger cable with LINE OUT audio. LINK Why did Apple not make a more powerful headphone amp? Size and power consumption no doubt.


Make your own preamp and mount it permanently?
Preamp electronic hobby kits, mono or stereo. I picked a few, put them in order of what looked like the best match for the iPod to intercom application.
http://www.electronickits.com/kit/co...ampl/ck704.htm
http://store.qkits.com/moreinfo.cfm/QK87
http://www.hobbytron.com/CK122.html
http://www.hobbytron.com/Preamp2WAmp...Assembled.html
http://www.hobbytron.com/vk2572.html

(A full 1 watt makes up for the sin of impedance miss-match. We are not talking hi-fi here, just getting acceptable volume. There are many suppliers of electronic hobby kits. Some kits above are more suited for battery operation 3v-9v, others work out the box on 12v-15v, suited for powering by the plane directly. You can make a little power supply voltage regulator if needed to may any of the above work off of ships power.)

[cguarino]

I have one of these that I use with my computer while flying on military airplanes. It works. Without it you cannot hear the sound at all. With it you can hear reasonably well. That's my $.02. Don't spend it all in one place.

[f1rocket]

I bought one to try and fix my iPod interface problems with my intercom. It didn't help. I've also used it with my headphone, which have a music input jack directly into them, and it doesn't add much there either. The music is plenty loud enough just plugged directly into my headset.

Now I have subsequently found out that my intercom music problems is probably my own doing because I don't have a ground wire installed that is needed. There's another thread on the subject so you might want to check your wiring first. I have not had the time to install the fix yet because it is about 5 dF in my hangar right now.

[tommylewis]

Ed, you should not need to add an amplifier to the PMA8000 because it has an internal amplifier with adjustable volume from the front panel by holding the AUX button, and repeatedly push the MUTE (volume up) or SPR (volume down) to step the volume level. There are 32 steps.

[edweeks]

Originally Posted by tommylewis

Ed, you should not need to add an amplifier to the PMA8000 because it has an internal amplifier with adjustable volume from the front panel by holding the AUX button, and repeatedly push the MUTE (volume up) or SPR (volume down) to step the volume level. There are 32 steps.

Wow, this is great! I'll try this first. Is this a documented feature? I thought I had read through the documentation pretty carefully looking for a volume control. Guess I missed it.

More generally, thanks to all for the help. I sometimes think that if I sent Doug 50% of the value of time and money I have saved from advice gleaned from this board, he'd be adding a wing onto his hangar.

Ed

[tommylewis]

Ed, this feature to adjust music 1 volume is documented now in the Sept 2006 rev 5 manual. When I bought my avionics I also had an earlier manual and only found out about this feature after calling PS Engineering twice to ask why my mp3 player volume was so low.

Hope it helps.

[vmirv8bldr]

Do a google search for CMoy pocket amplifier. I just built a couple of these this past weekend. I don't use them for input to a panel, so I cannot attest to their effectiveness there, but it works wonders on my iPOD. You can use it for Line out, or for headphone out. Fits in an Altoids tin. I have less than $20 in each of them. First one took about 8 hours to build. Second one took about 3.5 and is a much better product.

This is the most comprhensive instructional site I found:
http://tangentsoft.net/audio/cmoy-tutorial/

[rocketbob]

I helped a neighbor with this same problem; its simply an impedance mismatch. A $3 radio shack audio transformer will take care of the problem.