hugo

Re: 24ch API SUMMING MIXER DR-2402
« Reply #200 on: December 31, 2018, 04:54:31 PM »
Thank you but the manual don’t show if there are 1 or 2 star grounds (one for the psu, one for the unit).
On my unit, I reduced my noise by making like this :
- solder small pads on the psu board to have the ground passing through the pcb
- star ground on psu, at corner of pcb, connected to the iec inlet ground and to the pcb ac ground.
- psu xlr ground connected to dc ground of pcb

On the unit, I putted my star ground at the corner of the aca board, marked « ground ».
- this star ground is connected to the ground pin of the xlr Input  from psu, and to the channels boards grounds.
-regarding the manual, I removed the ground wire sitting between the +16v and the -16v of aca board because it is connected by the pcb to the star ground (at the corner of the same pcb)

With this I don’t have 2 points of ground connected together on multiple spots...

I don’t hear noise but my fabfilter eq shows -78dbfs in my daw (audio converters settings : +20db)
Is it a good noise level for this project or is there anything to make it even lower ?

Also, what is the 0 point at the output pot ? I have no gain/no loss with output about 4  o’clock..normal ?

Thank you


hugo

Re: 24ch API SUMMING MIXER DR-2402
« Reply #201 on: January 21, 2019, 10:00:29 AM »
Completed with a nice grounding / vu meter setted in Db VU
Everything works awesome, -90dbfs on my daw, no distortion.

TillM

Re: 24ch API SUMMING MIXER DR-2402
« Reply #202 on: January 21, 2019, 04:24:07 PM »
Hi Hugo,
what kind of DOAs are you using ?

Re: 24ch API SUMMING MIXER DR-2402
« Reply #203 on: February 14, 2019, 02:36:44 PM »
Oh man getting close now. After a long hiatus I`ve spent the last few days wiring this beast up. Powersupply is up and running, and most of the mixer wired up. Missing a couple of resistors for the aca/bo in order for the first power-up to take place...

I work shift ofcourse, so will be another couple of weeks before I have the time to finish it up, but it really feels in reach now. So looking forward to putting this to good use!

hugo

Re: 24ch API SUMMING MIXER DR-2402
« Reply #204 on: February 23, 2019, 02:01:00 AM »
Oh man getting close now. After a long hiatus I`ve spent the last few days wiring this beast up. Powersupply is up and running, and most of the mixer wired up. Missing a couple of resistors for the aca/bo in order for the first power-up to take place...

I work shift ofcourse, so will be another couple of weeks before I have the time to finish it up, but it really feels in reach now. So looking forward to putting this to good use!

Hi. Did you test one single channel ? Before having to swap one wire on all channels..

Re: 24ch API SUMMING MIXER DR-2402
« Reply #205 on: February 27, 2019, 02:27:13 PM »
Not yet. Isn`t the manual updated to be correct by now? Anyways, Ill be sure to try one channel first. Hopefully it`s wired right  8) (afaik the confusion stems from the volume pot having bottom and top terminals confused in the manual. That and the LED wiring is the wrong way around...?)

A little confusion around switches. As far as I understand "on - none - on" means that there is no center position for the toggle? Aka suitable for both the stereo channels mute switches and the main power switch.

I was hoping to use an illuminated switch for the +/- 16V, but am struggling to find one.
I`ve found this:

https://no.mouser.com/ProductDetail/NKK-Switches/M2122TCG01?qs=sGAEpiMZZMvudeGI7i40XMgdnVkjSffTQp%2F%2Fw8MWVxo%3D

but according to the data sheet, under "Contact materials and ratings", it`s marked as "G" aka Gold: "Rated 0.4VA max @ 28V AC/DC max" so probably not suitable? Being that the DR2402 will be drawing about 1.5 amps?

Re: 24ch API SUMMING MIXER DR-2402
« Reply #206 on: February 27, 2019, 02:32:14 PM »
oh yeah and here`s the switch I`m about to order for the stereo mutes:

https://no.mouser.com/ProductDetail/612-100-F1111

Re: 24ch API SUMMING MIXER DR-2402
« Reply #207 on: March 12, 2019, 10:32:03 AM »
Okay so first power-up worked fine. So far I haven`t run more than one board, and with its 8 opamps + 4 in the aca/bo section, my psu allready seems to be working pretty hard, as the heatsinks (the biggest that could physicly fit inside the psu enclosure) are getting quite hot (too hot to hold your finger on for more than a few seconds). Wondering how it`ll keep up when I add the remaining 16 opamps!

It sounds good and clean when running music through it. I am however experiencing some hum when all faders are wide open. Wondering how you are doing your noise measurements? This might be down to my at this point rudimentary cabling, will do some more testing before I "decide" it`s hum I hear, and just not the background noise. I mean, it`s right down levelwise with what I believe would be crosstalk (that I presume is the leakage of the channel I hear when the channel is muted but main fully open, and monitoring turned way up).

Also wondering on what level the LED`s turn red. They work fine and respond to the level by going from unlit to greenly lit, but I presume my Babyface pro doesn`t go loud enough to pass the "red threshold", as I`ve only tested it unbalanced where the max output of the RME is +13dBu (the mixer will be used with SSL converters in the future, which are 22dBu maximum i/o). The main xlr outs on the RME are +19dBu, I`ll give them a shot as soon as I`ve got the right cabling at hand (my whole studio is packed down at the moment, still trying to find a new nice space for it).

« Last Edit: March 12, 2019, 10:58:05 AM by fragletrollet »

hugo

Re: 24ch API SUMMING MIXER DR-2402
« Reply #208 on: March 15, 2019, 08:14:05 AM »
Hum is not normal, i never experienced any hum in this design, you have a ground loop. Check contact between all panels. Put your star ground at the corner of the aca board, called "gnd", to avoid multiple connections to the chassis. Pots does not influence the noise level in my build; full open or closed, i still get -90dbfs on my daw. With my audio interface setted up +18db, leds become red about -2dbfs on my daw, but it depends on the sound used..more bass take more level... check grounding and output transformers wires place. Keep them far from any psu cable. Its the best summing mixer ever, after testing few of them. Clean wiring is mandatory. Shielded wires for all pots, not needed for rear panel connections.