Re: DIY rotary DJ mixer
« Reply #120 on: October 12, 2018, 07:01:24 PM »
Also, I've been thinking about the preamps.. if they become unavailable I can probably fit new components and IC's but in general, how questionable it is to copy/reverse-engineer a PCB/schematic? Or would it be better to come up with a design and roll my own? I feel I haven't really DIY'd anything.. (edit : same goes for the EQ too, although I never really paid attention to filter design.. I'm not looking to sell these though, I'll be lucky to get it working in the first place.. maybe make another prototype with faders or something)
« Last Edit: October 16, 2018, 07:18:34 AM by efinque »


Re: DIY rotary DJ mixer
« Reply #121 on: October 16, 2018, 04:24:06 AM »
Cleaned the HP amp PCB a bit.. it's got jumper wires etc. I was thinking of getting rid of the whole thing (edit : I think it doesn't make much of a difference for home use, my PM-90 has about 1/5 useable range in the HP vol)
« Last Edit: October 16, 2018, 04:41:20 AM by efinque »

Re: DIY rotary DJ mixer
« Reply #122 on: October 23, 2018, 06:04:50 PM »
Tested with "ungrounded" pots.. doesn't make much of a difference though.

ruffrecords

Re: DIY rotary DJ mixer
« Reply #123 on: October 27, 2018, 07:09:30 PM »
Also, I've been thinking about the preamps.. if they become unavailable I can probably fit new components and IC's but in general, how questionable it is to copy/reverse-engineer a PCB/schematic?

Anywhere from questionably ethical to downright illegal.

As anyone can buy it, it is in the public domain. Therefore you can copy it unless the owner has copyrighted it (by simply placing a copyright notice on it) or by registering the design in which cases it is illegal.

Cheers

Ian
www.customtubeconsoles.com
https://mark3vtm.blogspot.co.uk/
www.eztubemixer.blogspot.co.uk


'The only people not making mistakes are the people doing nothing'

Re: DIY rotary DJ mixer
« Reply #124 on: November 09, 2018, 01:50:54 PM »
Took out the HP amp.. no sound whatsoever, I thought the line preamps alone would've sufficed (edit : for home use)

The problem with that in the long run could be the impedance; the headphones I've been using for testing are 55ohm (most DJ headphones are in that range)

EDIT : I'm also trying to get rid of pops in the master when switching the PFL source.. I remember reading a (shunt?) capacitor somewhere solves the problem.

EDIT 2 : some of the copper traces peeled off during soldering (I think it's because I had my iron at 450C), maybe rebuild it on perfboard?
« Last Edit: November 09, 2018, 02:41:14 PM by efinque »

Re: DIY rotary DJ mixer
« Reply #125 on: November 25, 2018, 03:00:42 AM »
Was just about to flag the previous post ,but it vanished , proper place for it in the bin , I hope no one clicked the links .

Re: DIY rotary DJ mixer
« Reply #126 on: September 19, 2020, 07:41:31 AM »
Stuff that's been changed :

-all the channel preamps (incl. master) now use 10-pin bus connectors except the mic channel (ie. they can be replaced with jumpers or another compatible module, line preamps have breakout wiring to the trim controls)
-stereo to mono summing where needed uses 10kOhm resistors
-HP out is now modified to use a cue/pgm blend (the grey pot next to cue select)



EDIT : here's what it looks on the inside:



The modules on the left are input channels (the blue things are the bus connectors, not the two which are in the front panel, they're mic on/off and EQ bypass switches).. the yellow "bar" in the middle is the summing bus. The master output preamp is next to it on the right as are the output transformers (the aluminium boxes), the PSU is the green PCB on the far right. The EQ is the blue PCB attached to the front panel.

EDIT 2 : I also bought some shrink tube which I was thinking of using for the PSU/mains wiring etc.. they're mostly hot glued for now. There's a bit of other mechanical stuff to tackle as well like securing wires, PCBs etc
« Last Edit: September 19, 2020, 03:53:05 PM by efinque »

Re: DIY rotary DJ mixer New
« Reply #127 on: September 23, 2020, 10:52:05 AM »
Here's a close-up of the modified monitoring/master section :



It now has split cue function, the cue select feeds the left channel (tip) of the HP out and the master feeds the right channel (ring).. with split enabled the channels are separate (you hear cue on the left and pgm on the right, the cue/pgm adjusts the balance between the two), with split off the tip and ring (L/R) are summed so you hear them from both cups.

To use it the way it was turn cue/pgm to cue and disable the split cue.

EDIT : the changes made to master section are only cosmetic as I had to make space for the monitoring modifications apart from connecting a ground wire that was loose.. I also put the headphone amp back in, it's kind of crowded in there though.
« Last Edit: September 23, 2020, 11:00:18 AM by efinque »