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DIY: Summer Projects

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Silou

Silou

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Is there anything that needs to be changed on the negative board, if I decide to change the gain resistors on the positive board?
 

solderdude

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The negative board always needs to stay the same.
It only inverts the output of the positive board and thus always has to remain at -1x gain.

Gain is determined solely on the positive board.
 
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Silou

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Just tried the K712 and the amp easily drives it aswell :)
The chassis arrives next week. I might wire the filters later on and test how well it works.
I will have to find a more elegant way to wire the volpot though.
Everytime I adjust the volume and accidentaly touch one of the volpots pins there is a loud scratchy noise and I nearly get a heartattack o_O
I think I will need one with a far longer shaft to properly mount it in the chassis.

What are the advantages of a motorized potentiometer? Is it only good for remote controlled volume?
 
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solderdude

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When you mount the volpot on a metal chassis all will be O.K. when the chassis is connected to ground on th + PCB.
In case you have an isolated front (or plastic) run a wire from the metal screw part of the volpot to a ground on the positive PCB and it will be O.K.
 
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Silou

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The chassis is completely made out of aluminium. I do not know if it is anodized aluminium though. Is it recommended to also ground the input and output sockets?
Found this article about wiring. The interesting part starts at site 24. He refers to the AES48 and says that every shield must be connected to the case.
 
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Silou

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I will gather my remaining questions here. Maybe someone else than Frans can answer them.

My DAC (Tone Board) has only one output, but I own two amplifiers I want to feed. There are three options I can think of:
1. use the Atom as a preamp
2. feed the input of the bridged O2 directly out again (like the Stax amplifiers)
How exaclty can I do that? Are there any disadvantages, if I just wire the inputs directly to the outputs? Probably reduction of signal if both amplifiers are on?
3. put the Tone Board in the bridged O2 case and solder wires to the analog outputs and connect the Atom to the soldered sockets
Reduction of signal again?
IMG_20190821_161628.jpg


Is it important that the Gain and Power switch wires are as short as possible? I want to put the Gain switch at the back of the case.

Another cool idea would be to get a Topping D10 and mount it inside the chassis and put the sample rate panel to the front of the case
 
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NTK

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I would think a pair of y-splitters at the output of your tone board should work. The tone board should be able to easily drive 2 separate amplifiers. Signal reduction will be negligible if the amplifiers are competently designed.

y_splitter.jpg
 
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Silou

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I would think a pair of y-splitters at the output of your tone board should work. The tone board should be able to easily drive 2 separate amplifiers. Signal reduction will be negligible if the amplifiers are competently designed.
I considered that solution aswell, but I do not really like it. Looks so "unprofessional" :oops:
 
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NTK

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I beg to disagree :D
Professionals, which I mean people doing it to make the money to pay rent and put food on the table, will do this kind of things without thinking. It is us amateurs that get hung up on looks :D
 
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Silou

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You are probably right about that. This is still a DIY project though and I invested quite a few hours in it already and want it to look as good as possible, because it will sit on my desk a long time (hopefully). I am the guy how gets annoyed by everything that is not perfect. Take my Tone Board enclosure for example: the USB-C cutout is not perfect. I can not see it. Nobody can see it. I am still annoyed by it and think about ordering a new enclosure because of it. I am special in that regard :D
 
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NTK

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I totally understand and appreciate that good tidy looks are important. What I said in my previous post was said in a tongue-in-cheek way. Please don't take offense. Many of us are doing this solely for fun, and we should make every attempt to maximize our enjoyment from our efforts. We all have our own obsessive-compulsive-disorders, and I certainly have plenty of my own. You aren't that special :D

Now that you are thinking about replacing the chassis of your tone board, may be two sets of outputs connected in parallel?
 
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Silou

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I am not really sure if the chassis is a good addition to my desk. What do you guys think? I think it is a bit too large for the desk. It will probably collide with my keyboard while playing games. The two O2 boards easily fit into a smaller case, but two rotary controls and three LED cutouts were just perfect for the project.
IMG_20190823_121207.jpg

(excuse the bad photo. I am not a good photographer and neither is my smartphone :D)
 
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NTK

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A pretty sharp looking setup :) Whether the bottom chassis is too big, only you can truly answer. But it does look a little big to me ;)
I don't know exactly what your setup is. I can see 2 unmarked black chassis. I know you have a Tone Board, and just built a balanced output 2xO2 amp (I am guessing you've not installed it into a chassis yet). What is in the other unmarked chassis? Provide a functional description/requirements of your setup can help us to understand what you want to accomplish.
 
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Silou

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The top one is a raspi with a Hifiberry Digi+ Pro used for streaming music. The middle one is the Tone Board and the bottom one is obviously a JDS Labs Atom. The chassis does not really fit to be honest. There is no better option though. No technical question this time. Just comment on the looks :D
IMG_20190823_121631_compress95.jpg
 

NTK

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I like the design of your rack :D Now this has become a problem of imagination (artistic mostly), which I am not very good at :rolleyes:
Are you driving your Tone Board through S/PDIF from the HiFiBerry instead of USB from your RPi?
 

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3. put the Tone Board in the bridged O2 case and solder wires to the analog outputs and connect the Atom to the soldered sockets
Reduction of signal again?

This... generally it is no problem in paralleling loads on the tone board.
However, when one of the loads is powered down there could be an issue.
Technically best solution would be to split the toneboard outputs using extra resistors.
So output toneboard via say... 560 ohm resistor to output RCA and directly to O2 input (it has an input resistor on it).
You could replace R3 and R7 with 560 ohm but the input caps would have to become smaller, say 47 pF.
 

solderdude

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Is it important that the Gain and Power switch wires are as short as possible? I want to put the Gain switch at the back of the case.

Yes it is important as any induced current here is amplified x gain. Keeping it short helps.
 
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Silou

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I thought about the DAC "problem" today and remebered that still I have my old SMSL M3 sitting in its box. Plugged it in and I instantly remembered why it was in its box. There is a lot of static noise at higher potentiometer positions. I tried it with an optical connection, but the static noise was still present . I unplugged it from the computer then and powered it with my powerbank. Static noise was gone, but it sounded a bit flat. Probably because the powerbank was nearly empty. Tried it with an USB power supply (5V 2A) and it worked perfectly again. How is that possible? I have no such problems with my Tone Board that is powered by the same computer. There is no problem if the M3 is powered by an USB power supply, but the signal comes from the PC via USB.
 
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Silou

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Are you driving your Tone Board through S/PDIF from the HiFiBerry instead of USB from your RPi?
That was the plan, but I do not really use the raspi that often to be honest. The Tone Board is connected to my computer via USB and the raspi is connected via SPDIF with the Tone Board.
 
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