Build Thread - A New Take on the Classic Pass Labs D1 with an ESS Dac

opc

Member
Paid Member
2004-10-15 10:57 pm
Ottawa, Ontario, Canada
There is a critical design update here:

http://www.diyaudio.com/forums/digi...sic-pass-labs-d1-ess-dac-173.html#post3662046

Please read this before ordering any parts!!!! I will update the BOM attached below at some point and see if I can have up replaced.


Hi Guys,

This will be the official build thread for the I/V stage PCB group buy. Please post all build related questions here.

Also, feel free to post pictures of your build, chassis ideas, parts suggestions etc...

I'll start things off with a final schematic and SMD BOM which people will need for the build. I'll have a BOM posted for the remainder of the PTH parts, and it will include all the parts I used in my build.

Cheers,
Owen
 

Attachments

  • OFFICIAL BOM.pdf
    24.4 KB · Views: 1,700
  • OFFICAIL SCHEMATIC.pdf
    124.3 KB · Views: 3,921
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compare the 2 BOMs and what is missing you buy. mostly just spdif input TX, PTH caps, heatsinks for the regulator section (unless you choose to get a larger sink than the conrad MF12-151) the regulators, 200R resistors, molex connectors/headers, input and output jacks, standoffs etc etc.

BTW guys, sorry for the lag on the pics, I was expecting the Zfoils today so held off, but tracking ended up adjusting the delivery date due to some computer glitch meaning they had to be processed manually, most likely will still turn up tomorrow, they are sitting about 10km away and would be pretty slack for them to sit there for 3 days, but then this IS UPS we are talking about
 
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opc

Member
Paid Member
2004-10-15 10:57 pm
Ottawa, Ontario, Canada
Hi Guys,

I've attached a new updated BOM with all parts needed for the DAC. These are all the parts that I used in my build, so I can vouch for all of them working well. Not everyone will need every part on the list, and some people may need parts that are not on the list, like the connectors to the Buffalo DAC. Please review the BOM carefully and decide what you may or may not need for your particular build.

I have also attached a power dissipation calculator at the request of qusp. It's an Excel file, and all you need to do is punch in the rail voltage you want to use, the resistance values you're using (usually 200 and 400 ohm) and the DC voltage before the regs. Common values are already in there, so you may not need to change anything.

All the individual dissipation as well as total dissipation values are on there.

For reference, using the suggested Antek transformers and 45V rails, your total dissipation including the regs will be about 48W. With transformer losses, you'll be drawing a little over 50W from the wall.

Enjoy!
 

Attachments

  • OFFICIAL BOM - COMPLETE.pdf
    30 KB · Views: 1,236
  • Power Dissipation.zip
    4.6 KB · Views: 446

opc

Member
Paid Member
2004-10-15 10:57 pm
Ottawa, Ontario, Canada
Hi Guys,

I've got another build related file to post up here for all those who have been asking about capacitor values for the ? caps.

The short answer is: Don't populate them - they will probably do more harm than good.

If you really want to use the four caps to roll off at a desired frequency, then you're welcome to use the attached simulation and LT spice to figure out what values you need. It's not as easy as calculating two RC low pass filters. Once you start simulating, you'll see what I mean.

I will not be offering any help with these simulations, and if you don't know how to run LT spice, then you're out of luck. The values I simulated and then measured were pretty close, but I did need to tweak the values a little bit to get reality to match up with the simulations. If you can use LT Spice and you have a way to measure FR up to 1MHz, then you should be able to tackle this.

Cheers,
Owen
 

Attachments

  • Cap Simulation.zip
    668.2 KB · Views: 161
My small contribution to the cause.
You can cut and paste the following to make the digikey order.


5,WM3843-ND
8,493-1960-ND
4,495-3942-ND
5,WM1021-ND
10,WM3112CT-ND
5,HS346-ND
3,LM317TFS-ND
2,LM337TFS-ND
10,492-1073-ND
4,490-2888-ND
4,490-2880-ND
1,490-2879-ND
1,493-1807-ND
1,493-1726-ND
4,FQA32N20C-ND
4,MP930-200F-ND


Davide
 
800ma 2 x 25vac 45-50va x 2. also since you are at digikey, I would recoimmend switching to LT317 and LT337 instead of LM317 and LM337. the linear tech regs are much better, think they were about 3.50-4.50 each there. they are identical in every important characteristic, but much lower noise and much better transient
 
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actually probably more like 760ma for the whole board, not each channel, as each leg is 120ma x 4 = 480, then you need a separate lower current TX for the dac and the buffalo II uses about ~250ma @ 5vdc. but i'm going to go back and have a look now just to check so i'm not posting definite bogus info. i'm using a much larger TX as my regs take far more current

Zfoils are here on the last day they had, paid bloody 77USD for shipping to take a week!! normally this service would take 2-3 days and they have been here in australia since last friday, but there was a computer malfunction at UPS and customs couldnt access the clearance files, so everything had to be done manually. today was the very last day they had as was the max time they quote so they would have received a strongly worded email from me if they didnt arrive today, asking for a refund for shipping.

they really look very cool, as do the SMD Zfoil 1206 size resistors I got for my portable sabre IV. texas instruments are a funny bunch, kindof like an uber high tech cottage industry, they really look precision but also hand made and finely crafted, like I can picture am old man cranking these out looking over his half glasses at the instrument panel of the laser trimmer.

pics tomorrow when there is some light may also have the stuff from PCX and if i'm lucky, my digikey order
 
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opc

Member
Paid Member
2004-10-15 10:57 pm
Ottawa, Ontario, Canada
Hi Guys,

Good work on the list Davide! I still suggest that people take their time and really consider everything they might need.

The one thing I left off the list was the 0.1" connectors I used between the Buffalo and the I/V board. I bought a 3 pin, two 5 pin, and one 9 pin, then I pulled out every other pin so that they would fit. The problem is, they cost a bloody fortune, and they're really not worth it. I think those little things cost me almost $55 for both the M and F connectors, and when you look at them in your hand you think "oh that looks like maybe 50 cents worth".

The better way to go is to just buy the cheap strips and cut them to length, or just use wire.

For the transformers, you need two of the following (one per channel):

Antek - AN-0540

Either match the specs, or just buy those ones.

- Minimum 35VA, but 50VA is pretty much ideal.
- 2 x 40VAC secondaries.

For the transformer for the DAC I would suggest:

Antek - AN-0006

- 5VA
- 6VAC secondary

Cheers,
Owen