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

indeed best options are offboard IMO and you can just use them as the interconnects to connect to the outputs and wire the 10K across the XLR instead of the SMD at the PCB outputs. things are starting to get back to normal here, but things have gotten far worse before they got better. again ive not been directly effected as in not underwater, but the damages bill has now gone up to 10 billion with another 20 billion damage to the economy!! death toll rose to 20 and now victoria has been hit with the same sort of flooding. this is going to be sooooo massive its not funny.

also today after some houses just had power restored there was another massive storm that knocked out 25000 homes power, many of which just had it restored. 50000 homes without power in QLD

found out what the delay was with the heatsinks, they had to do again as they mistakenly anodized AFTER they tapped them, meaning the taps were too small. so they did them again, spoke to Julian yesterday and they should ship today, hopefully I will have them by the end of the week.
 
Is this board suited for running single ended output dac's? I have the DAC END with AD1865 that I want to try this with. Thanks.

Boards are all over, and are intended for DAC with balanced output.

On the other end, as far as I understand (and I can be very wrong) the circuit is a kind on dual single-ended, so you could make one half and use it. I wanted to try it with the DAC-END.

D.
 
I finally got my fets from Mouser,did a late night\early morning matching session,and my NTD1 is singing!!!:sing: It needs some running in, but so far I'm happy.:yes:

I've been playing around with the bias/input voltage,trying to find the "sweet spot". I started with the Twisted Pear prescribed AVCC/2 formula and then readjusted to AVCC/2-1 . The higher input voltage seemed to be a little more bass heavy. I will need to do some more testing to get some more definitive conclusions, after I've lived with it for awhile.

It measures quite well,so well in fact,it may be below the baseline distortion of my PC test system,more test time needed to establish accuracy/repeatable results.

Thanks Owen for sharing and facilitating this GB!! GREAT WORK!!!!:cheers:

IGWT
 

opc

Member
Joined 2004
Paid Member
Hi IGWT,

Congrats!!! You're the first one here to get your DAC done I think! I'm really glad you finished it up, and I'm glad its performing well for you!

Snap a few pictures if you get the chance. I'm always curious to see how others will finish their units.

As for measurement, it's going to be a challenge measuring with a PC. The Audio Precision I use is a $50,000 piece of equipment and even then it's still at the limits of what it can measure. I think a direct loopback with the AP gave -112dB THD+N, and with the Buffalo and NTD1 it was sitting around -111dB.

Nikon1975:

I've attached a list of caps that could be substituted for the Epcos parts a specified. Try to stick with the polypropylene caps, and the value really depends on the impedance of the next stage. Generally, I'd try to stick with 10uF or more.

Cheers,
Owen
 

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Hi IGWT,


Nikon1975:

I've attached a list of caps that could be substituted for the Epcos parts a specified. Try to stick with the polypropylene caps, and the value really depends on the impedance of the next stage. Generally, I'd try to stick with 10uF or more.

Cheers,
Owen

Thank you for the suggestion.

About what I am going to connect to the DAC, I seek your advice. I have the following options.

1) Connect the DAC straight to a balanced F5. Basically I have a four channel F5. I use two channel for the left and two for the right. The negative output tied together and the speaker connected on the two positive.
Use volumite for volume control

2) Connect the DAC to SE F5 using "the wire" as bal to se converter. As volume control here I have various options: volumite, simple pot (what value?) or two CDB1 with a 20k pot.

What do you think would "fit" better ?

Thanks,

Davide
 

opc

Member
Joined 2004
Paid Member
Hi Davide,

You can certainly try both options, but if it were me personally, I'd put my money on the first option.

I'm presently using a pair of line arrays for my main speakers, and they require a huge amount of power to drive, which means bridged F5 amplifiers are not an option.

When I swap to a speaker that doesn't need so much power though, then I'll be using exactly the setup you described in option #1. I really love the F5 amps, and I like them even more in a bridge setup. Using the F5 amps with a Buffalo, a volumite, and the NTD1 would be pretty ideal.

Regards,
Owen
 
This is what I thought. I have almost all the components for the second F5, one is already done. And once you have done it once the second one is easier.
The one I have now is "as described" in NP article, including component choice. I am not sure if I want to twick it around. How did you have your ?

Sorry a bit OT.

D.
 

opc

Member
Joined 2004
Paid Member
Hi Davide,

The F5 has an input impedance of 100k which means you could get away with 0.47uF and get a -3dB point of 3.4Hz.

I would plan for the future though, and allow room for at least 10k loads, which would require a 4.7uF for the same -3dB point.

I went ahead and tossed a 22uF in there which means I can drive 600 ohm loads and still have a -3dB point well below 20Hz.

If you know that you're going to be using just the F5 amps for a while, then I would suggest having some fun, and just using a 0.47uF which would allow you to splurge on something fancy if you're into that.

Cheers,
Owen
 
Hi Davide,

The F5 has an input impedance of 100k which means you could get away with 0.47uF and get a -3dB point of 3.4Hz.

I would plan for the future though, and allow room for at least 10k loads, which would require a 4.7uF for the same -3dB point.

I went ahead and tossed a 22uF in there which means I can drive 600 ohm loads and still have a -3dB point well below 20Hz.

If you know that you're going to be using just the F5 amps for a while, then I would suggest having some fun, and just using a 0.47uF which would allow you to splurge on something fancy if you're into that.

Cheers,
Owen

I tested with D1B1 (22uF) + 10K pre-amp. It sounds good.
But when I add a 1800uF Cap (like formal schematic), the bass could improve more! Truly amazing... according to calculation. 1800uF is not necessary, but the effect is there...
 
1800uf is there in case you dont have money or desire for large film caps. it was only put there in the schematic as an option and OPC never expected anyone to actually USE it ;)

BTW guys the heatsinks are here, arrived late yesterday, so I can get on with it. i'm actually rather excited, because I have the rest of my dream dac pretty much assembled
 
yeah tomorrow, not mounted though as my IV isnt done, but you'll get the idea. I will of course have crazy amounts of incentive to be a matching machine now, to get it all over with and pick the perfect match for me and get my dac finished; as its the only thing stopping it from being fully operational.

I have a meeting with my landlord on monday about some things that need doing around the place and of course for him to eyeball us. I wont have much time tomorrow to work on it, as I need to take measures to stop my end of the house looking like a mad scientist/terrorist workshop; but this week is full steam ahead.

Of course I now have a massive glut of work just come in, but I want to get this done asap. still will have to do work too, but I'll be able to get a better idea of how long its going to take, with being able to do at least 2 devices at once now should be able to get at least 20-25 devices done a day I would think, once I get into a rhythm probably more.

its pretty chunky guys haha, especially after upping the size to the MF20-151
 
hey OK here we go, sorry for the day late, had a lot on my plate yesterday.

as you can see its pretty chunky, but also pretty neat. the holes are perfectly tapped, so glad we got this done!! initially the size we were getting was perfectly snug against the sides of the PCB but after further math was decided it would be too small to risk. so changed from MF12-151 to MF20-151. makes it quite a bit wider, but makes for better mounting as you can see I had room to put some chunky M4 taps at the corners; which will be used for nice copper brackets and mounting my umbilicals for the ackodac. also i'm going to use these to mount various other parts of the build probably including the caps (not directly on there of course) connections to the power supply will be made from underneath for hose of you using the stock PCB power supply, if I were you I would also try the transformers under there and see if there is any noise.

at first I wondered why they hadnt rotated it to make it fit neatly, but then I realized they had probably only seen my PCB. doesnt matter after further thought I realized it will make for better airflow over the surface of the sink
 

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