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Post by chinook9 on Jan 30, 2015 3:43:52 GMT
A few weeks ago I decided I would like to build a DAC. I started a thread in the "Other Gear" section and after a bit of information gathering moved forward on the project with frequent communication with Javier. In recent PMs with Javier we decided to start a new thread here and provide somewhat of a commentary on the build. I also expect to have quite a few questions as I move along and I will ask these questions here also. I will answer any questions about the build. I probably know less about electronics than almost everyone on these DIY forums so I expect to have quite a few questions. I only studied electronics for a couple of weeks in 1964 so there is not much I can figure out myself. I have built a Sunrise II and one of Frans' filters for my T50RP but that's the limit of my experience. I do have a 60 watt soldering station that I consider essential. There are a number of DAC kits available including the JLSounds DAC, The Buffalo (from Twisted Pear Audio), and the AckoDAC. These three vary in cost quite a bit and all get good reviews. I settled on the Buffalo. I'm not sure exactly why but it uses the Sabre ES9018 chip, has really good documentation, and there is quite a bit of discussion (including photographs) regarding the Buffalo on various DIY forums. The Twisted Pear Audio USB to I2S module is not as well regarded as some of the others so I decided to go with an "Isolated XMOS DSD DXD 384kHz USB to I2S/DSD PCB with ultralow noise regulator" from DIYINHK. This is similar to what the completed DAC should look like. My plan is to make a simple sheet metal chassis for initial building and testing. If all goes well I will either buy a commercial enclosure or make an enclosed ventilated enclosure out of sheet metal. In the next few posts I will list the various DAC modules/components I have purchased along with pictures. I will return and edit this first post as I think of anything I have left out. PLEASE CLICK ON PICTURES FOR EXPANDED VIEW.
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Post by chinook9 on Jan 30, 2015 5:46:39 GMT
The Buffalo DAC board that I purchased is the Buffalo IIISE stereo DAC. This DAC board and chip are capable of 8 channels but, I only want stereo. I believe it is also programmable but I know little about that. I will explore it in the future. The BIIISE board is sold complete except for connectors which I will install. I'm not sure how many connectors I need to install for my build but I believe it is five on this board. Size 55mm x 95mm. Four shunt regulator modules are installed on the DAC board. An AVCC Dual Shunt Regulator Module. To install this I will attach connectors on both the AVCC module and the DAC board. This picture makes it look much bigger than it is. Its 30mm x 25mm. Three Trident Trident Shunt Regulator Modules (Two 3.3V and one 1.2V). I will attach connectors to these modules also. Size 27mm x 20mm. The connectors used facilitate easy installation and removal. I believe only three graphics per post so...
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Post by chinook9 on Jan 30, 2015 5:52:20 GMT
IVY-III is a balanced active I/V line stage. As with all the Buffalo module the IVY is very flexible. I will only be using the single ended (SE) outputs from the IVY. Size 106mm x 85mm. The buffalo and the Ivy are designed so that the Buffalo sits on posts directly over the IVY and is connected electrically by two set of four pin connectors. ` PlacidHD BP 2.1 Bipolar Power Supply with 2.5-inch heatsinks. This provides power to the IVYIII. Size 114.3 x 101.8mm. PlacidHD 2.1 Power Supply with 2.5 inch heatsinks. This provides power to the DAC board. Size 114mm x 50.8mm.
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Post by chinook9 on Jan 30, 2015 5:52:31 GMT
9V+9V (30VA) Power Transformer is the power source for the Placid HP. 60mm diameter x 28mm high, weight 400gm. 15V+15V (50VA) Power Transformer is the power source for the Placid HP BP. 76mm diameter x 30mm high, weight 600gm. These transformer look the same. I have read that these can be stacked but I will mount them independently. DIYINHK isolated XMOS DSD DXD 384kHz high-quality USB to I2S/DSD PCB with ultralow noise regulator. I purchased the optional indicator light module, however, at this point I'm not sure where I will mount it. The LEDs are not mounted so I might run wires from the board to LEDs mounted in the chassis. I'm not sure if that could provide audio problems, however. No need to worry about that for a bit.
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Javier
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Post by Javier on Jan 30, 2015 18:47:11 GMT
Looking very neat, congrats!
Have you received the DIYINHK adapter?
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Post by chinook9 on Jan 30, 2015 19:40:47 GMT
Looking very neat, congrats! Have you received the DIYINHK adapter? Hello Javier, Apparently I missed something. What adapter would you be referring to. Everything I ordered from DIYINHK was the USB to I2S as pictured above plus a couple of connectors they include.
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Javier
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Post by Javier on Jan 30, 2015 20:22:49 GMT
Sorry, I should have used the full name: USB to I2S adapter. BTW, you should power the isolated side of it using the BIII's own 3.3V output (it sio located by the I2C connectors, not to be confused with I2S, the former is for control the latter for sound) and not from the Placid.
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Post by chinook9 on Jan 30, 2015 20:48:06 GMT
Sorry, I should have used the full name: USB to I2S adapter. BTW, you should power the isolated side of it using the BIII's own 3.3V output (it sio located by the I2C connectors, not to be confused with I2S, the former is for control the latter for sound) and not from the Placid. Excellent! Yes, I received it from HK last week. I don't believe paying extra for express shipping helped much. I don't have much to do on the IVY so I have put that on hold for a few hours as it is not critical path. I am reviewing all the documentation and developing a list of questions. Many of these I can probably answer to but I don't want to take the chance of being wrong. I will start on the chassis in the next couple of days. I just need to identify the SPDIF/I2S switch, and the BNC connector that I will use so I can punch the correct sized holes in the enclosure before bending it. Is using RCA connectors rather than BNC for the SPDIF cable likely to make a discernable difference. Just your opinion, of course.
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Post by chinook9 on Jan 31, 2015 15:08:33 GMT
Hello Javier! I have read and reread all of the guides and studied the PCBs quite a bit. I am feeling good about what has been done and what I have to do but I have a few questions concerning items I'm not real sure of: Can you confirm the following related to adjustments of the Placid HD and Placid HD BP: Using VR2, voltage adjustment, should be 5.25 volts on the Placid HD, and 15 volts on each rail of the Placid HD BP? All measured at the outputs. Using VR1, current adjustment is 440mA (440mV) on the Placid HD, and 90mA (90mV) per rail on the Placid HD BP? They indicate the range on the BP is 90-150mA with 90mA at idle. I am continuing to research this. The more I read, the less I think this is correct. This morning (1/2) I read a post by Brian that states "...adjust the CSS current to a level that leads to 50-60mA of shunt current, which means 50-60mV over TP-out to TP-shunt. Adjust both power supplies..." That may apply to my situation but I'm not sure and I'll keep reading. Is the Placid HD BP connected to the IvyIII at Pwr3? I do have the power supply jumpers installed. Is there an accepted "best" way to connect the primaries for the two transformers to the 115V wires from the power entry module. I have faston connectors to use at the entry module but I'm not sure how to combine the four positive and four negative wires from the transformers. I can get two of the wires into a faston connector but not four. How about something like this? rather bulky, and ugly, but will work. Do I need to use shielded wire for the SPDIF/PCM-DSD switch? I would use two wires of a four wire Canare cable. There are no pears to match on the new AVCC board, however, it appears there is only one GND connection and each side of the boards that will line up. Is that correct? As you suggested, I will install the connectors so it will only go on one way. Do I need to connect anything to the reset header on the DAC board? I haven't read any reference to use of this at all. I will connect the chassis to ground. Is it correct that the DAC, PSU and signals are not grounded to the chassis? I have not seen any reference to anyone doing this. I believe I can use TTL and consumer level SPDIF without any adjustments. Is this correct? Is there any point in installing the 24 pin unshrouded header at EXT-10 on the DAC? I can't see that I'll be using it. Should the SPDIF/I2S switch, volume control, RCA connectors and BNC connectors be isolated from the chassis? Initially I would do this with electrical tape but buy isolated components for the final build. Thank you, Brian
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Javier
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Post by Javier on Feb 1, 2015 19:44:09 GMT
Can you confirm the following related to adjustments of the Placid HD and Placid HD BP: Using VR2, voltage adjustment, should be 5.25 volts on the Placid HD, and 15 volts on each rail of the Placid HD BP? All measured at the outputs. That is correct, 5.25V into the Buffalo DAC board and +/-15V into the IVY board inputs. Measure after 2-3min of powering on to make sure they have warmed up. Using VR1, current adjustment is 440mA (440mV) on the Placid HD, and 90mA (90mV) per rail on the Placid HD BP? They indicate the range on the BP is 90-150mA with 90mA at idle. I am continuing to research this. The IVY uses approx. 90mA when idling, as in no signal going through, and will uses up to or slightly over 150mA when at full tilt as in receive the maximum possible signal form the BIII DAC board (0dB). You should initially try to adjust VR1 to 500mA (without load) for the HD and approx. 210mA (without load) for the HD BP. These values are spec+60mA headroom. Once you connect the loads (BIII and IVY) measure gain when playing music and adjust VR1 to max measured load +60mA as a safety margin. Too much headroom will only waste electricity and generate more heat. I am reading up on shunt current. I know where to check it but I don't know what its supposed to be or what the range is. Electrics are not my field but as I understand it shunt power supplies need to "burn" a current continuously to run properly, if it is not used by the device it feeds then it is "shunted" to ground generating heat. Is the Placid HD BP connected to the IvyIII at Pwr3? I do have the power supply jumpers installed. When you have the jumpers installed you can use any of the three inputs, just connect the one that makes wiring easier/more convenient. Is there an accepted "best" way to connect the primaries for the two transformers to the 115V wires from the power entry module. I have faston connectors to use at the entry module but I'm not sure how to combine the four positive and four negative wires from the transformers. I can get two of the wires into a faston connector but not four. How about something like this? rather bulky, and ugly, but will work. As you are in the US you should wire as per the 1st example of the manufacturer's pdf: Transformer manufacturer's manual (link from Twistedpear page) That is, twist Blue/Violet together on one hand and Grey/Brown on the other. No need to use any adapter, just get them together in the header and screw them tight. Do I need to use shielded wire for the SPDIF/PCM-DSD switch? I would use two wires of a four wire Canare cable. No, you can use any wire. There is no current or signal going through it. Just keep it, as with any other cable, as short as possible. There are no pears to match on the new AVCC board, however, it appears there is only one GND connection and each side of the boards that will line up. Is that correct? As you suggested, I will install the connectors so it will only go on one way. That is correct, make sure you use the connectors as I told you to avoid accidental damage Do I need to connect anything to the reset header on the DAC board? I haven't read any reference to use of this at all. No, leave it as it is. I will connect the chassis to ground. Is it correct that the DAC, PSU and signals are not grounded to the chassis? I have not seen any reference to anyone doing this. It is not strictly necessary to connect the chassis to ground if you are careful and do things right but of course it'll be much safer. Should you connect the DAC board to the chassis GND insert a 100nF cap + 100 Ohm resistor in parallel in the path to get rid of noise. Maybe Frans can help with this as he is the expert in that area? I believe I can use TTL and consumer level SPDIF without any adjustments. Is this correct? SPDIF input is consumer level only, if you want TTL you will lose I2S as they share same inputs. As all CD players or PCs use consumer level and you've bought a USB to I2S adapter I see no reason to use TTL SPDIF. Is there any point in installing the 24 pin unshrouded header at EXT-10 on the DAC? I can't see that I'll be using it. You can indeed leave it out. Should the SPDIF/I2S switch, volume control, RCA connectors and BNC connectors be isolated from the chassis? Initially I would do this with electrical tape but buy isolated components for the final build. AFAIK the vol pot is already isolated so no need for additional isolation. Ditto for the switch. Most quality RCA and BNC connectors come with plastic washer for isolation and if they are mounted properly they should not make contact with case.
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Post by chinook9 on Feb 1, 2015 20:29:42 GMT
Excellent Javier! I think things are progressing quite well.
What software did you use to make insert the red line on the graphics of the two boards. I did this many years ago but I don't remember the software I used.
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Javier
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Post by Javier on Feb 1, 2015 20:59:57 GMT
I used "Micorsoft Office Picture Manager" and "Micorsoft Paint", nothing fancy.
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Post by chinook9 on Feb 1, 2015 21:03:15 GMT
I used "Micorsoft Office Picture Manager" and "Micorsoft Paint", nothing fancy. Thank you. Edit: Will be gone for a couple of days. Have company coming Thursday and have started working on the enclosure. Using 20ga "paintable" sheet metal. Very stable once edges are folded and its pretty easy to work with.
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Post by chinook9 on Feb 13, 2015 3:34:44 GMT
Finally back to the BIIISE. I have finished the chassis and will begin mounting components in the next couple of days. The chassis came out alright, but it was a bit more difficult to get the bends right than I had expected. Eventually I will put a ventilated cover on this chassis or buy a commercial enclosure from Modushop.biz. I will ground the enclosure with a star ground to the mains but all PCBs and through chassis components will be isolated. I will twist all power cables and they will be routed a minimum of 10cm from the chassis. Javier, before I power up any components, and possibly toast something, I may post my planned power and signal connections for your review. As always, any recommendations will be appreciated.
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solderdude
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Post by solderdude on Feb 13, 2015 6:16:25 GMT
I would build up the power supply on a bench first. connect it to each other (so no PCB's other than power supply) and test it under a load. Verify the output voltages and ONLY then connect it to the PCB's.
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