Testing audio system with Dynon Alarms

Pmerems · #1 09-27-2009, 08:00 PM

Gents,

I have a Dynon 180 and a Flightcom 403 intercom. I have been testing the Dynon alarms which are connected through the Aux input of the 403.

I made a ?junction? to feed the Alarms, music and Garmin 496 alerts into the intercom. Currently the 496 isn?t connected up. I used the schematic provided by Dynon to input the mono alarms into the stereo intercom. I tested it with a potentiometer and settled on 15K ohm resistor.

When testing the system I notice a slight HUM in the background when no music or alarm is turned on. However when I turn on the IPOD (not playing music) the HUM goes away (something to do with impedance). I also notice the alarm volume level drops when the IPOD is connected and not playing. The only items powered up during the test were the Dynon and the intercom.

It sounds like A/C HUM but I am running off the battery. If I shut the Dynon off the HUM goes away. I disconnected the alarm pins at my "Aux input junction" to see if it was my audio wiring was causing the problem but the HUM went away. I even shut off my florescent lights to see if that was the cause, but it wasn?t.

With only the Dynon and intercom powered up there aren?t a lot of electrons moving throughout my wiring so I am a bit confused. The HUM is definitely coming from the alarm inputs and the Dynon.

I am not an electrical guru so if there is anyone who can help me stop this unwanted HUM, It would be appreciated. Maybe a capacitor along with the resistors?

SteinAir · #2 09-27-2009, 08:58 PM

Hi Paul,

Clip the Dynon wire and don't look back. Your issue is common and the truth is that the flightcomm just doesn't play nice with the Dynon audio output and the quickets/cleanest solution is just to forget about it. You can play around with some resistors to try and balance it, but in the end the typical person ends up cutting that orange/white wire anyway....

My 2 cents as usual!

Cheers,
Stein

breister · #3 09-28-2009, 12:50 PM

I am assuming no HS34 - I would agree with Stein, buzzers are not cool in my book anyway. The HS34 voice alerts are kind of nice, and I got them working fine with my Sport 200S; that too took some tinkering with resistors.

Pilottonny · #4 09-28-2009, 02:25 PM

OK, maybe a bit off-topic, but I have a little problem with the Dynon audio also.

I do have the HS34 and wired the voice alerts into the intercom paralel with my SL30. I used the 10k potentiometer as per Dynon diagram and have a 100 Ohm resistor on the SL30 line.

Everything works, but I feel the volume of the dynon will be barely loud enough in flight, with the potentiometer tuned to "max volume". Also when I transmit, I hear myself a bit distorted in the headset. When I tested transmission quality with a handheld, the reception was fine though. Audio quality when speaking on the intercom between pilot and co-pilot is excelent.

Anybody know, if I can improve the volume of the Dynon voice alerts and get clearer tranmittal audio on the headset, by changing the potentiometer and/or the rsistor in the SL30 line?

Any input would be welcome.

Regards, Tonny.

N941WR · #5 09-28-2009, 03:16 PM

This is exactly why I went with the iCom radio. The thing has three mono inputs and that is where I connected the Dynon's. The audio alarms come on clear with no hum. Even the voice warnings from the AP74 are clear and not too loud.

breister · #6 09-28-2009, 06:38 PM

I don't know about other audio panels, but the Intercom I have has two different sorts of inputs. One is for radio, the other for "music." Inputs to the music channel come across louder than from the Radio input (same input source).

There may be something similar on the intercoms.

frankh · #7 09-28-2009, 08:50 PM

my PMA 7000 works wonderfully with the Dynon's 'SCARE'S THE PANTS OFF YOU" audio alarm..no noise and the Ipod is awesome.

Not that that helps.

Frank

vlittle · #8 09-29-2009, 08:29 AM

Quote:

Originally Posted by Pilottonny

OK, maybe a bit off-topic, but I have a little problem with the Dynon audio also.

I do have the HS34 and wired the voice alerts into the intercom paralel with my SL30. I used the 10k potentiometer as per Dynon diagram and have a 100 Ohm resistor on the SL30 line.

Everything works, but I feel the volume of the dynon will be barely loud enough in flight, with the potentiometer tuned to "max volume". Also when I transmit, I hear myself a bit distorted in the headset. When I tested transmission quality with a handheld, the reception was fine though. Audio quality when speaking on the intercom between pilot and co-pilot is excelent.

Anybody know, if I can improve the volume of the Dynon voice alerts and get clearer tranmittal audio on the headset, by changing the potentiometer and/or the rsistor in the SL30 line?

Any input would be welcome.

Regards, Tonny.

Hi Tonny.
I've built both passive and active audio mixers for aircraft applications. The passive mixers, such as you are using, can work fine in simple applications, but audio levels may be limited.

For an example of a passive audio mixer, look at the schematic in the back pages here: http://vx-aviation.com/documents/AMX-1A.pdf.

For active audio mixers, my favourite is here: http://vx-aviation.com/page_2.html#AMX-2A_more.

I designed both of these, so I'm biased. The AMX-2A, in particular is very flexible with 10 amplified input channels, 4 of which are variable level. This allows fixed-level sources (like Dynon alarms) to be adjusted to be a comfortable audio level.

Vern

flyvans.com · #9 09-30-2009, 01:54 AM

hi tonny!

just battled similar problems and am glad to report success :-)

SL-30
the bad squeal when transmitting comes from the mic gain and sidetone settings. funny that the icom200 worked like a charm out of the box while the sl-30 needed all kinds of settings.

try mic gain: 40-50
sidetone: 80

with a gma-340, this gave us similar results as with the icom200 out of the box.

Aux Volume
what intercom are you using?
we've had an issue with some noise and a very very weak aux input. traced it finally to mixed up wire colors in the audio panel harness, only had to switch polarity. we're using an http://www.fdatasystems.com/AP_60.htm ap-60 line mixer.

however in the process, learnt some things:
- try hooking up an aviation headset directly to the dynon wires. if loudness is fine, then the problem is on the intercom/mixer... side. quality doesn't have to be great in the headset, just volume.
- if it's already low there, some kind of preamp for the dynon wires will be required.
- if it's only low in the intercom i would suggest these 3 steps:

1. check wiring polarity for the aux in, i know it sounds dumb ;-)

2. play around with the sl-30 settings. try increasing the intercom volume while turning down the sl-30 volume. there are some rather "hidden" settings in the sl-30, e.g. the main sl-30 volume button might not be working if for some reason a value different than "variable" is set on the "headphone level" if i remember correctly. also, it's kind of a pain that the settings are spread over two different configs. one is the SYS & <-> at power on menu, the other settings are in the SYS com options. (also the interface logic isn't the same in both menus, once you have to press select and enter, in the other you can simply adjust)

3. as vern little suggested, using one of the various line mixers might be the solution in your case if you're only loosing a little bit of volume.
also, play some more with the sl-30 settings.

hope that helps,

kind regards,
bernie

Pilottonny · #10 09-30-2009, 05:14 AM

Bernie,

Thanks for the info.

OK, I will try that setting for my SL30 and see if it sounds better, but if I remember correctly, the problem is gone when I disconnect the Dynon.

I am not using the intercom Aux. input for the Dynon Voice alerts. The Aux. input is switched and may not announce your alarms when they are most needed! Also I am using the Aux. for music, for the passenger.

Vern had already suggested his device, in a previous thread, before I hooked everything up, but other people suggested there is no problem in adding two signals together, into the intercom. Since I want to keep it simple, light and cheap (you will know that we pay approx. double the price of what we buy in the USA, ones we pay the shipping, import duties, customs fees and VAT) that is what I did. Although it works, I am wondering if it will be OK in flight because I have de Dynon Potentiometer at max level already and it is not "to loud". What I am wondering is, if I swap the 10K potentiometer for a 5K potentiometer, will the Dynon signal be louder? And what will this do to the SL30?

Regards, Tonny.