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Poor Man's version of the Monster GO DJ (Read 1850 times)
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Re: Poor Man's version of the Monster GO DJ
Reply #15 - Sep 11th, 2020, 9:06am
 
First Power Up!
 
It Works!

 

 
A few things to note:
 
1.  Note wires on left side.  It is currently powered from +5VDC from my bench supply. The battery is not installed, and as you can see, the battery meter board is not in the circuit.
2.  Film is still on, knobs not installed.
3.  It basically works/sounds pretty good, but it does have a few issues.
4.  The sound effects board was not working at all.  After hours of troubleshooting, I finally discovered that the problem was due to my bench power supply.  I was very conservative in setting the PS current limit -- Just in case.  With each of the tone/op amp boards having lots of filtering, it was presenting a large initial load on the PS.  The current limiting was apparently causing the voltage to come up in a way that hung the sound effects board.  Nominal (steady state) current is almost exactly 0.25A, but in rush is over 0.5A.  With the PS current limit set higher, everything powers up OK, and it does play the sound effects.
5.  There was an issue with the Cue/Live switches due to a short resulting from the close soldering on the tiny toggle switch contacts.  This was fixed, but I'm still not sure if something is wrong with the Cue switches/cue bus wiring or not.  More testing will be done to determine if there is still a wiring problem or not.
6.  Generally, control ranges are pretty good.  One significant problem is that the fader does not fully fade out the opposite player when fully faded to the other side.  I don't have a solution for this at the moment.  It is fundamental to the way the fader pot is made, and a relatively high impedance downstream of the fader.  It's more of a problem because the player modules do not stop at the end of a track -- they go on to the next track, so unless the gain for that side is turned down, or the player is stopped, the next track will be heard faintly in the background.  More thought is necessary on this issue.
7.  I will experiment with different options for power/battery/battery board configurations.  Hopefully I'll make a decision on the configuration today.
8.  It seems at least acceptable from a noise/interference point of view.  I may line the bottom panel with grounded aluminum tape just for shielding "best practices".
9.  The effects keyboards are not sticking to the chassis.  I will remove them, add 3M outdoor permanent double sided tape, and re-attach them.
 
Once I get the power system configured as it will be, and I have installed knobs and removed the protective film, I plan to do a video showing how it works.
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Re: Poor Man's version of the Monster GO DJ
Reply #16 - Sep 14th, 2020, 1:59pm
 
Here's a pretty much final picture:
 

 
 
Current Status/Notes:
 

  • It runs from the internal LiPo battery.  I went with the separate boost converter to go from battery voltage to the +5V.  The charger/display board handles charging and battery level only. Battery life seems to be pretty good.  As mentioned, it draws less than 0.25A.  With a 5000mah battery, it will last longer than any party I will ever get invited to.
  • The issues with the cue switches was due to a short from soldering in very tight spaces.  2 soldering/wiring issues have been corrected.
  • I have not fixed the issue of the fader not completely silencing the opposite channel. Since the fader (and the headphone cue/live mixer) are just wired as resistors in the line-level audio instead of actual stage gain controls, they are not going to fully cut off the audio.   More engineering is needed.  I am not sure how much more effort I want to put into this project.
  • I turns out that the fader (linear potentiometer) board was not wired like I though it was.  Basically, both sides are wired in parallel on that board. The result of this was that it was not actually playing in stereo. I had to de-solder and re-work the board to make it 2 electrically independent pots.
  • If you look closely, you can see that I re-taped one of the membrane keyboards, and that the other is sill coming up near the center.  I'll re-glue this when I have the time and patience to do so.
  • Labels are not installed.  I have made some labels with Libre Office.  Again, I'll print, cut, and apply them when I have the time and patience to do so.

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« Last Edit: Sep 14th, 2020, 3:08pm by Administrator »  

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Re: Poor Man's version of the Monster GO DJ
Reply #17 - Oct 24th, 2020, 9:34am
 
I used my Poor Man's GO DJ for an actual gig last night.
 
I was hired to DJ for a small car show in my local area, so I decided to take my PM GO DJ along as a back up.  The Stanton SCS.4DJ was my primary Player/Mixer.  Early in the evening, I got a request from the wife of the venue owner for Thriller by Michael Jackson.  I was certain I had loaded up Thriller, as well as a hand full of other Halloween classics on both the thumb drive I use with the Stanton, and the SD cards in the PM GO DJ .  However, I was unable to find Thriller on the USB drive I had in the Stanton.  I verified that Thriller was on the SD cards in the PM GO DJ.  Since the Stanton does not have an SD card slot (add that to my list of complaints), I couldn't simply swap or add media.
 
I figured this was a good enough excuse to actually try live DJ'ing on the PM GO DJ in front of a live audience.  It took a moment of down time to switch over, but the PM GO DJ connected to the amp I was using, and Played the request flawlessly.  I stayed with the PM GO DJ for several tracks before switching back to the Stanton SCS.4DJ.
 
Despite the previously mentioned limitations in the Media Players used in my PM GO DJ, it was actually quite usable.  Here are some more observations.
 

  • The font on the PM GO DJ Media players is much larger than the tiny font on the small Stanton display.
  • The Stanton Browse list does not retain the directory structure of the media, so you cannot use the media's directory structure to organize your tracks.  The media players in the PM GO DJ do retain the directory structure.  While I generally just have folders for artists, one could also use folders basically as crates, or any other structure you would like (such as a directory for "Halloween Songs").  Of course you can create playlists on the Stanton, but that would be tedious using the Stanton interface itself, or would require using other software on a PC.  Simply using the directory structure for crates or playlists may not be sophisticated, but it is simple and easy.
  • Quickly moving through large numbers of tracks is actually just as easy or easier than on the Stanton. Quickly browsing the browse list on the Stanton using the jog wheel is not smooth, and suffers from lag.  You either have to scroll slowly enough for it to keep up, or risk significant overshoot.  As mentioned, the Media Players used for the PM GO DJ are fast and direct if you just keep mashing the >> or << buttons.
  • The combination of the Media Players not stopping at the end of the track, and the Fader not totally silencing the opposite (faded away from) player leads to the next track playing in the background if you forget to stop it.  I think I did this for over half the tracks I played using the PM GO DJ.  I should state that the level of the undesired track is very low, and I don't know if it was noticeable to the audience or not when it happened.
  • While the PM GO DJ has 2 mic inputs (as opposed the the Stanton's single mic input), they do not pass through, so they can only be used for recording.  A live mic input is really needed, and it would be nice if it had equalization.

 
I'm still planning on doing a video demonstration. Check back for a link soon.
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Re: Poor Man's version of the Monster GO DJ
Reply #18 - Nov 20th, 2020, 7:04pm
 
Finally -- As promised -- The demonstration video:
 
 

 
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