Has anyone had good luck with the aux in stereo mod?

wrybread · Post by **wrybread** » 10 Feb 2021, 16:08

I just did the line in mod to my sc-815, and it sounds very distorted. And on my previous car I never had any luck doing it with the sc-816.

I used the instructions here, connecting to the rear of the tapedeck on my sc-815:

http://atthetipwebs.com/technologyinstr ... eo_mod.htm

And interestingly my phone doesn't detect that it's connected to a stereo and doesn't enable it's output. That's true with both the sc-815 and sc-816. And devices that do work with it sound absolutely terrible.

I triple checked my work, there's no solder bridges, I used two different cables (one a shielded rca), but still no joy.

Stumped.

wrybread · Post by **wrybread** » 10 Feb 2021, 16:43

Aha and oops, I think it's my bluetooth adaptor. I plug headphones into it and those sound bad too.

wrybread · Post by **wrybread** » 10 Feb 2021, 20:32

On a sidenote, I see some posts from people saying they were able to remove the tape from a cassette and still use it with the mod. When I do that the tapedeck just spits the tape back out. Is there a trick to using the mod without actually running a tape over the heads and playing the hiss? Maybe some way to snip the output from the tape head?

wrybread · Post by **wrybread** » 10 Feb 2021, 22:55

Partial success! It sounds awesome when playing music from my laptop, but when I connect my Android phone via it's headphone jack, the phone doesn't detect that anything is plugged in and keeps playing from it's internal speaker.

And my phone's headphone jack works fine with a pair of computer speakers or headphones.

From some quick googling I think I might need to add a resistor between one of the pins and ground. If anyone happens to have any clues, please let me know.

But progress!

(Edited to add: I think I need to add a 16 to 32 ohm resistor between ground and right, which I'll do where my cable is soldered to the tape deck)

wrybread · Post by **wrybread** » 10 Feb 2021, 23:38

More progress: if I connect an inline volume controller my phone recognizes that something is plugged in and starts playing audio. Sounds great too. Whoo hoo!

I'm using this guy:

: 41UjK1QGceL._AC_SX466_.jpg (20.88 KiB) Viewed 1867 times

Interestingly it only works with the volume knob on full volume. If I turn it down at all it goes almost silent. And sometimes when I first plug it in I need to turn the volume down then up to get it to be recognized.

But getting there. And when it's working it sounds phenomenal. This is much more fun than listening to NPR or the same thriftshop CDs again.

Post by **abscate** » 11 Feb 2021, 04:24

wrybread wrote: ↑10 Feb 2021, 20:32 On a sidenote, I see some posts from people saying they were able to remove the tape from a cassette and still use it with the mod. When I do that the tapedeck just spits the tape back out. Is there a trick to using the mod without actually running a tape over the heads and playing the hiss? Maybe some way to snip the output from the tape head?

I use a copy of Great Music of the 1970s

It’s mostly a silent soundtrack

Post by **wizechatmgr** » 11 Feb 2021, 09:28

I've had great luck with this little gem...

https://www.amazon.com/gp/product/B082Y ... UTF8&psc=1

wrybread · Post by **wrybread** » 11 Feb 2021, 09:38

I use a copy of Great Music of the 1970s It’s mostly a silent soundtrack

Ha. I'm using the outgoing message tape from an old answering machine cassette I found, which is all silent except for the very start of the first side, where someone with a heavy accent thanks me for calling.

I've had great luck with this little gem...

Does your CD player work? If so it would be interesting to play the same thing on CD and your phone and compare the sound. I've never found a radio transmitter that sounds as good.

wrybread · Post by **wrybread** » 11 Feb 2021, 18:22

Today was an excellent day in Volvoland for me. I tested the impedance between R and common of a few pairs of headphones, and all were 30 ohms, except one pair of "high impedance headphones", which were 50 ohms. The headphone jack that I added to my stereo only had 5 ohms though... I had a pack of 47 ohm resistors lying around so I soldered it between R and common on the PCB:

: 20210211_124318.jpg (190.31 KiB) Viewed 1826 times

Now my Samsung phone detects the input! On the bench at least... Once I reinstalled the stereo and powered it on it wouldn't detect it again. I'm guessing it's interference from the tape deck, sure would be nice to completely remove the signal from that. Measuring the impedance I see it shoots to either an extremely high or low impedance, I'm not quite sure which. Either way it's outside the range that makes my phone happy.

The impedance goes back to 47 ohms when I turn the tape deck off (by powering off the head unit or simply changing to FM), and then if I connect my phone it detects the input. Which is a workaround I can live with, for awhile at least: connecting my phone before powering on the head unit. It seems to then continue to work well until I unplug it, meaning stopping playback or switching apps still works fine. That'll probably get old, but for now it's a small victory.

And I tested with an iPhone 7 and apparently this issue doesn't affect it, it works fine at all times, even if I connect it with the tape deck on, so maybe this issue only affects Android phones, or maybe just the Samsung S9+. I'll do some more testing as more phones come my way.

And my newly installed phone mount is working well too, although I need to find something to cover the screw.

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Also in the progress department I came up with an easy way to keep my stereo powered on even when the car is off: just connect the purple/yellow wire from the stereo harness (the wire that gets power when the key is turned) to the positive line from the hazards switch, which is very nearby. Eventually I'll add a switch to the dash to toggle it, but for now this'll do. Coming soon: same mod to the 12 volt cig lighter sockets.

And very happy with my roof racks, newly wrapped in "blue steel" rope, which is used by commercial crab boats. In theory this won't rot in the sun, though I'll believe that when I see it. It'll at least last a long time, and I found it washed up on the beach anyway.

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Post by **abscate** » 12 Feb 2021, 04:49

It won’t. It’s polyolefin and very Uv resistant and floats like polypropylene ( which has crappyUV life)

It’s great for anchor markers and lines that won’t foul your propellor, but it is soooo expensive we can’t afford it, unless I find some holding lobsters in a box , which I set free.