ProtoDAC TDA1387 X8 project

[Skip Pack]

Hi All,

I assembled my 'test' version with a socket for the dac assemblys and mundane IV resistors. I need to clip some of the leads on the bottom, and have a question: I was advised long ago that it is best not to trim leads after soldering, and I always bend thin leads over to hold position and clip them before soldering. The advice rationale was that the shock of the snap when clipping could crack the solder joint. With two sided and through hole plating I suspect that is much less valid today. With the thick leads on the RCA outputs there will be a fair amout of 'snap'. I'm inclined to reheat such post-clipped joints just on principle even if they look good. What is peoples' experience here?

I also have to 'unclothe' one of my RPi 4Bs before testing.

Thanks,

Skip

[hifinet]

I bend, solder then clip. Then examine all joints with a loupe. Not sure if that is the proper technique. If the solder flows through the plated hole to the top side, I think the chance of failure is very low. One thing to be aware of is to apply much more heat to the pads that connect to the ground plane, due to the heat sink effect. Those are pin 5 of the module, the two ground leads of the I/V resistors and the ground leads of the RCA jacks. Also, GPIO header pins 6 and 14.

[fdealexa]

Hi everyone,
personally, I prefer to cut the terminals of the components before soldering, without bending them (avoiding problems in case of any disassembly).
Best regards,
Francesco

[michaelagiles]

Great Appreciation to Mark! I received my DAC this week and it is SWEET! It was a long and arduous process to get through customs - no thanks to son of NAFTA - but with MW's dedication and integrity he got it done. Thanks Again!
MG

[rh2018]

@Skip Pack - It's true that some side cutters apply excess shock to a solder joint when trimming leads. I find Xuron Micro-Shear Flush Cutter best for PCB work. Solder then clip. No need to re-flow.

https://www.amazon.com.au/Xuron-170-II-M...6464&psc=1 

It's also good practise to remove flux with Isopropyl alcohol and do a final visual with a loupe as @hifinet suggests.
Richard

[Skip Pack]

@Skip Pack - It's true that some side cutters apply excess shock to a solder joint when trimming leads. I find Xuron Micro-Shear Flush Cutter best for PCB work. Solder then clip. No need to re-flow.

https://www.amazon.com.au/Xuron-170-II-M...6464&psc=1 

It's also good practise to remove flux with Isopropyl alcohol and do a final visual with a loupe as @hifinet suggests.
Richard

Thanks to all for your responses. I'll pick up some of the recommended cutters. I always do the alcohol cleanup of flux, so that's good.

Skip

[Skip Pack]

Another ProtoDac lives! After some adventures getting the socket right -- ask me for specifics if you think you want to use one, I got it going. I used the same resistors for I/V as the input resistors (430R) and the 10uf Wima MKP4 output caps. This is sort of a 'baseline' build, and I've got the foil I/V resitors and two types of polycarbonate film caps for the dacs I hope to use and cherish long term.

My initial impressions are wildly positive. It complements my system very well compared to the Allo Boss2 I disconnected this morning.
I'll refrain from much comment for a few weeks, though I will say that given the cost and the ease of construction, with or without the expensive bits (that I've not heard yet) you won't regret getting one going.

To fill in the context: I'm running Moode 8.3.3 on a 4GB Rpi 4B with the ProtoDac output going to a Neurochrome That Driver based preamp that is SE in and true balanced out. That connects to a Neurochrome Mod86 poweramp (first generation), connected to MarkAudio 11MS drivers in the small Nostromo cabinets the Scott Lindgren of Woden Design designed around the time of the driver's release. 

I'm eager to see how the dac develops and to work on the best Moode configuration to optimize the system. Thanks, of course to Mark and the others particpating in this endeavor.

Skip

[Tim Curtis]

You may want to try this CamillaDSP config. It does polarity inversion and uses the nice CamillaDSP volume control with dither for 16 bit. 

Copy to "/usr/share/camilladsp/configs/ProtoDAC VC.yml"

Code:

devices:
 adjust_period: 10
 capture:
   channels: 2
   extra_samples: 0
   filename: /dev/stdin
   format: S16LE
   read_bytes: 0
   skip_bytes: 0
   type: File
 capture_samplerate: 0
 chunksize: 4096
 enable_rate_adjust: false
 enable_resampling: false
 playback:
   channels: 2
   device: hw:0,0
   format: S16LE
   type: Alsa
 queuelimit: 1
 rate_measure_interval: 1
 resampler_type: Synchronous
 samplerate: 44100
 silence_threshold: -60
 silence_timeout: 3
 stop_on_rate_change: false
 target_level: 0
filters:
 Dither:
   parameters:
     bits: 16
     type: Simple
   type: Dither
 Volume:
   parameters:
     ramp_time: 200
   type: Volume
mixers:
 stereo:
   channels:
     in: 2
     out: 2
   mapping:
   - dest: 0
     mute: false
     sources:
     - channel: 0
       gain: -3
       inverted: true
       mute: false
   - dest: 1
     mute: false
     sources:
     - channel: 1
       gain: -3
       inverted: true
       mute: false
pipeline:
- name: stereo
 type: Mixer
- channel: 0
 names:
 - Volume
 type: Filter
- channel: 1
 names:
 - Volume
 type: Filter
- channel: 0
 names:
 - Dither
 type: Filter
- channel: 1
 names:
 - Dither
 type: Filter

[Onionhead]

Recently it  was suggested I might consider the ProtoDAC kit as a replacement for my Allo Piano DAC with reclocker rig. Would prefer to have it in a case but I have not seen pics of completed DAC in a case. If anyone has case options please post. Much appreciated.

[Tim Curtis]

Here are cases that I use when there are several HAT'S on top of the Pi.

Older "dog bone" case. Not sure if this is still available.
   

Newer case meant for stacked Pi's. Still available AFAIK.