MP3 Trigger Echo or Warble Sound Issue

Community Projects
1

Hi folks. I built this for a DJ friend of mine and he loves it. One issue is the RCA jacks produce some what of an Echo. He calls he calls a warble sound. The small phono-out does not do this, clear. This is what it sounds like clear:

http://www.youtube.com/watch?v=KXc-cXVO40E

For those of you who don’t know, the PHONE has a DC Bias, and it is recommended that you decouple it as shown by these links:

http://www.sparkfun.com/datasheets/Widg … output.pdf

"Par 3 - Line-out Connection It’s not recommended to use GBUF as audio ground when connecting to other electrical equipment such as power amplifiers or PC line-inputs. The GBUF pin is internally biased to 1.25V and it is possible that a ground loop is formed when the GBUF is connected to the ground of the target device. This may damage the
VS10XX device and will prevent normal operation."

Or this link: http://www.zachpoff.com/diy-resources/i … 3-trigger/

http://www.zachpoff.com/site2/wp-conten … 74x300.jpg

Here is the project. You can see I put in the 100 ohm resistor in series, with 10uf cap, and a 10K resistor to ground for each channel.

http://imageshack.us/a/img834/1838/0ing.jpg

http://imageshack.us/a/img443/426/3nlx.jpg

http://imageshack.us/a/img802/3900/vkl7.jpg

2

I can tell you that I do not do that with my Triggers… Just run the audio to an amp (https://www.sparkfun.com/products/11044) and works perfect.

3

codlink:
I can tell you that I do not do that with my Triggers… Just run the audio to an amp (https://www.sparkfun.com/products/11044) and works perfect.

Your amp decouples both input lines (C3/C4).

http://dlnmh9ip6v2uc.cloudfront.net/dat … %20v10.pdf

4

Ah, there ya go. That’s why it just works…

5

gmcjetpilot:
One issue is the RCA jacks produce some what of an Echo. He calls it a warble sound. The phone out does not do this, clear. This is what it sounds like:

http://www.youtube.com/watch?v=KXc-cXVO40E

I can't hear anything amongst all the background talking. Doesn't the Trigger just have 1 set of L/R/GBUF outputs ? What's the difference btw your RCA jacks and your phono jack wiring ? If you connect the phono out to his RCA ins (w/a patch cable), does the "warble" still happen ?

http://www.djsoundandlight.co.uk/image/ … 00x800.jpg

6

I don’t know anything about that product, but your description of the sound rings a bell. I have heard that warbly, echoing sound when a stereo output was fed into a mono input using one output as the ground (i.e., stereo L to amp input, R to ground). It results in a L-R or R-L signal and sounds weak and “echo-y”

It can also sound like that if you feed a stereo source into a stereo amplifier and the ground is floating. Are you sure of your wiring?

7

Here is the video of the sound.

http://www.youtube.com/watch?v=oDar_gYwRdU

As far as all of your comments, YES he has already used the 1/8" phono… Sounds good… AGAIN do you all know what a DC offset is? If NO, the MP3 trigger has a DC 1.25 volt offset and is NOT common to the power ground. If you connect to an amp with a ground loop from the amp back to the power to the MP trigger, that could be BAD… The set up I have is RECOMMENDED by Sparkgap…

8

gmcjetpilot:
AGAIN do you all know what a DC offset is?

[https://forum.sparkfun.com/viewtopic.ph ... uf#p128703](https://forum.sparkfun.com/viewtopic.php?f=20&t=28657&p=128771&hilit=+gbuf#p128703)

https://forum.sparkfun.com/viewtopic.ph … uf#p137906

Nope, we’re all dummies. Geeeesh …

Do you have 30 years experience as an EE debugging all manner of problems ? Since I don’t know what you did exactly, I ask questions. But don’t worry, I won’t be doing that anymore.