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Amplifying Audio outputs

Planecrazy232

Planecrazy232

Well Known Member
My D100 and TruTrak audio outputs are very weak. I do not have an audio panel. I have the audio outputs tied into the input of a PM1000 intercom along with the radio output into the intercom. I could put resistors on the radio output to bring that level down, but I don't think the Dynon and autopilot will still be loud enough. Is there a small amplifier that can be installed between the intercom and my audio outputs?
 
Instead of spending money on an amplifier you might consider upgrading your intercom to a PM3000. It would have the input connections you would need. It has the same footprint as the PM1000. I don't know for sure but my guess would be your existing harness would need only just a wire or two changed for your inputs. I would think by the time you spend money on an amplifier you would have the same amount in the PM3000.

Just my .02.
 
Sub-D DB-25 reversed, and wiring order different

I have the same problem and got excited about Steve's solution, but I believe the two units are set up opposite. The PM3000 has the pins (male) on the unit (intercom) side, and the PM1000II has the pins on the D-sub plug side (wiring harness). The instruction manual for the PM3000 says, "Sub-D DB-25 Male on unit." The PM1000II says, "Sub-D DB-25 Female (Sockets) on unit. The wiring order is also completely different. Check it out - PDF installation instructions on the PS Engineering website.

Still a worthy solution to the problem because I noticed several units on Ebay starting at $170.
 
Brian Vickers said:
I have the same problem and got excited about Steve's solution, but I believe the two units are set up opposite. The PM3000 has the pins (male) on the unit (intercom) side, and the PM1000II has the pins on the D-sub plug side (wiring harness). The instruction manual for the PM3000 says, "Sub-D DB-25 Male on unit." The PM1000II says, "Sub-D DB-25 Female (Sockets) on unit. The wiring order is also completely different. Check it out - PDF installation instructions on the PS Engineering website.

Still a worthy solution to the problem because I noticed several units on Ebay starting at $170.
Click to expand...
even if the harness does not match up it would still not be a difficult task of detaching the wiring from the old D-sub connector and inserting into the appropriate location on the PM3000 D-sub connector. Wiring of these is not complicated at all. The hardest part is being able to see those little tiny numbers on the connector to know you have inserted into the correct hole. :p I still think it the better option. Good luck.
 
I had the same issue getting AOA audio out of my D10A and alarms out of my D10 since I also have a PM1000II with only one aux input - used this for a music jack. I added a MakerPlane 10 channel audio mixer AMX-2A under the panel, located so I could get at the volume pots easily. $120 +-. This also saved a bunch of panel space. Info available on line. Vern Little (MakerPlane principal/designer) is a VAFer. I forget his call sign.
 
It isn't that the Dynon (or likely TruTrak) are quiet and need amplification, it's that you can't just hook audio output wires together and have them mix. One of them wants the voltage to be 0V and the other wants it to be 5V, and they fight one another. The stronger one wins. Sounds like the strong one is your radio.

What you need is a mixer that combines signals. One option here is the VX aviation mixer for about $120:

http://store.makerplane.org/10-channel-audio-mixer-mono-amx-2a/

If you want to play around, a resistor on the radio might actually work OK, but it would require some playing around with the values.
 
Brian Vickers said:
I have the same problem and got excited about Steve's solution, but I believe the two units are set up opposite. The PM3000 has the pins (male) on the unit (intercom) side, and the PM1000II has the pins on the D-sub plug side (wiring harness). The instruction manual for the PM3000 says, "Sub-D DB-25 Male on unit." The PM1000II says, "Sub-D DB-25 Female (Sockets) on unit. The wiring order is also completely different. Check it out - PDF installation instructions on the PS Engineering website.

Still a worthy solution to the problem because I noticed several units on Ebay starting at $170.
Click to expand...

Also be careful which model PM3000 you choose. The 170.00 versions are not correct as the do not have the unswitched audio inputs. The models 11931A or 11933A are the correct versions.
 
dynonsupport said:
It isn't that the Dynon (or likely TruTrak) are quiet and need amplification, it's that you can't just hook audio output wires together and have them mix. One of them wants the voltage to be 0V and the other wants it to be 5V, and they fight one another. The stronger one wins. Sounds like the strong one is your radio.

What you need is a mixer that combines signals. One option here is the VX aviation mixer for about $120:

http://store.makerplane.org/10-channel-audio-mixer-mono-amx-2a/

If you want to play around, a resistor on the radio might actually work OK, but it would require some playing around with the values.
Click to expand...

I thought about resistors on the radio side, but the volume on the D100 is so low to start with that once the engine is running I can't hear the tone even with the radio off. Does the device above raise the level?
 
Anthony,
The D100 is quiet because your radio is smashing it down. When you hook multiple audio sources together, the strongest one wins, and when the strongest one wants there to be no sound, all others get very quiet because they have to fight that one.

The resistor makes the radio "weaker" which means all other sources will get louder while the radio gets quieter. It's not perfect, but it might work.

The mixers do not specifically amplify, but they mix signals without allowing one to block the others. The D10A's output is specifically meant to be quite loud and in most installs a volume control is needed to turn it down.

You can prove the D10A can be loud easily- Disconnect the radio and the TruTrak and run the test sound on the D10A and it should be very loud. You might be able to do this just by having the TruTrak and radio powered off. This will show you how loud it would be if you didn't have the connections paralleled.
 
Another possible course: does your radio have auxiliary inputs? My Icom A210 does. If so, you can keep one going through the intercom and route the other directly to the radio, that way they don't compete with each other, and can probably then be controlled volume-wise independently. Good luck.
 
dynonsupport said:
Anthony,
The D100 is quiet because your radio is smashing it down. When you hook multiple audio sources together, the strongest one wins, and when the strongest one wants there to be no sound, all others get very quiet because they have to fight that one.

The resistor makes the radio "weaker" which means all other sources will get louder while the radio gets quieter. It's not perfect, but it might work.

The mixers do not specifically amplify, but they mix signals without allowing one to block the others. The D10A's output is specifically meant to be quite loud and in most installs a volume control is needed to turn it down.

You can prove the D10A can be loud easily- Disconnect the radio and the TruTrak and run the test sound on the D10A and it should be very loud. You might be able to do this just by having the TruTrak and radio powered off. This will show you how loud it would be if you didn't have the connections paralleled.
Click to expand...

I have tried exactly that. D100 only into the system and it's the same volume. So if I tame down the radio everything will be equally quiet.
 
Planecrazy232 said:
I have tried exactly that. D100 only into the system and it's the same volume. So if I tame down the radio everything will be equally quiet.
Click to expand...

"Tame down" is not a very good description. Basically some output circuits can look like a dead short if tied to other outputs. It sounds paradoxical, but putting 330 ohm or so resistors on every output, prior to tying them together, can increase all of the volumes.
Step 1: if you have only a single device's output connected to the intercom's input, the volume should be okay. If not, stop. You have a problem with that device's wiring, or an internal volume setting, etc.
Step 2: Once all devices, individually, work as per step 1, then put a 330 ohm resistor in series with each device, including the nav or com radio. Tie them all together at the intercom input.
Step 3: If you are not happy with the results from step 2, you can buy or build a mixer. If you are handy with a small soldering iron you can build your own. Cost is $3, not counting any box or connectors. PM me your email and I'll send a schematic that I know works, because it's what I use.
 
Another answer

Connect the audio output of each source to its own 150 ohm 1/4 watt resister, connected to a 10uf/16 volt DIP Tantum capacitor. Simply the resistors and capacitors are in series. Then connect all the outputs together, then to audio input. You can get the parts from Digikey.com. You can change the resister to balance the audio level, but start with 150 ohms.

Audio Source --- 150 ohm --- 10uf -----|
Audio Source --- 150 ohm --- 10uf -----|------- to audio input
Audio Source --- 150 ohm --- 10uf -----|

Hope this helps. It does work and is a very simple mixer circuit.

Brian
 
FYI, you don't need that resistor and cap on the Dynon D10A, that's basically exactly what is inside. We have a 1K resistor however, so that's where I'd start on other devices too.

However, Anthony says that he's physically unplugged the TruTrak and the Radio and the D10A is still quiet. Not sure what to do with this as the output swing of the D10A is 16V P-P, which is very loud in almost all systems. I agree that if the D10A is still quiet with the other devices completely unplugged (not just turned off) then something else is up and a resistor mixer won't help.
 
dynonsupport said:
FYI, you don't need that resistor and cap on the Dynon D10A, that's basically exactly what is inside. We have a 1K resistor however, so that's where I'd start on other devices too.

However, Anthony says that he's physically unplugged the TruTrak and the Radio and the D10A is still quiet. Not sure what to do with this as the output swing of the D10A is 16V P-P, which is very loud in almost all systems. I agree that if the D10A is still quiet with the other devices completely unplugged (not just turned off) then something else is up and a resistor mixer won't help.
Click to expand...

For clarification I have a D100 not a D10A if that makes a difference.
 
Sorry about that. There is no difference in the D10A or D100 audio output circuit, so it doesn't matter.
 
Confession

dynonsupport said:
FYI, you don't need that resistor and cap on the Dynon D10A, that's basically exactly what is inside. We have a 1K resistor however, so that's where I'd start on other devices too.

However, Anthony says that he's physically unplugged the TruTrak and the Radio and the D10A is still quiet. Not sure what to do with this as the output swing of the D10A is 16V P-P, which is very loud in almost all systems. I agree that if the D10A is still quiet with the other devices completely unplugged (not just turned off) then something else is up and a resistor mixer won't help.
Click to expand...

So I have a confession. This audio problem has been a nagging one for me for some time. I thought I had isolated my audio sources from the radio on multiple occasions. I've separated them before they get to the intercom, had the Comm radio off, removed the intercom, etc with all the same results- low sound from my autopilot and the D100. Then it dawned on me. Turn the system on and while listening to the alerts, remove the Comm radio. Alas- LOUD alerts!! You were right all along. I put 500 ohms and 20mfd of capacitor in series with the Comm radio and now both the D100 and the autopilot can be heard perfectly now. And still plenty of volume out of the Comm. Thanks for the encouragement!!
 
Same audio issue with MGL iEFIS lite

Interesting to read about low audio output from the Dynon as I have the same problem with my MGL 8.5 inch Explorer. Maybe the one difference is that I'm feeding the audio into a PS Engineering PMA 6000M that has no gain adjustments for the aux 1 & 2 inputs. Keep in mind that the MGL audio input is the only input on one of the aux ports so there is no interference from another audio device. I have several other devices feeding the second aux port and they all work fine; however, they have their own gain controls.

I have tried 3 different audio amps (slightly different circuits and chips all 3 with a pot on the gain) coming from the MGL iEFIS with the same result, no improvement on two of the three and the third reduced the basic volume to 0 amplification.

I can send a schematic of the 3 circuits if it would help resolve the problem any ideas to fix this issue would be appreciated.
 
wiring question

dynonsupport said:
Anthony,
The D100 is quiet because your radio is smashing it down. When you hook multiple audio sources together, the strongest one wins, and when the strongest one wants there to be no sound, all others get very quiet because they have to fight that one.

The resistor makes the radio "weaker" which means all other sources will get louder while the radio gets quieter. It's not perfect, but it might work.

The mixers do not specifically amplify, but they mix signals without allowing one to block the others. The D10A's output is specifically meant to be quite loud and in most installs a volume control is needed to turn it down.

You can prove the D10A can be loud easily- Disconnect the radio and the TruTrak and run the test sound on the D10A and it should be very loud. You might be able to do this just by having the TruTrak and radio powered off. This will show you how loud it would be if you didn't have the connections paralleled.
Click to expand...


I have the Audio Out from my GRT 4000 wired to Aux 1 input on my Garmin GTR 200. I was planning to splice the Audio Out from my Dynon D6 into this, without the 10 kΩ variable resistor.

Will this work?

Doug
RV-7
(the last 90%)
 
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