I've just bought this dac and the design (at least the output stage with 6 op amps) looks quite similar to yours.
https://www.ebay.co.uk/itm/274226725245
Location: London/Durham
Posts: 6,878
I'm Lawrence.
I've just bought this dac and the design (at least the output stage with 6 op amps) looks quite similar to yours.
https://www.ebay.co.uk/itm/274226725245
Location: London
Posts: 182
I'm Greg.
Interesting! Looks good!
Certainly cheaper than mine ;-) I feel like an idiot spending all that time - but it is part of the fun I guess.
As far as I can see it really looks good. Good power supply (probably the most important part in any dac - there are so many examples of diy dacs using humble dac chips but where a lot of attention has been given to the power supply).
Op amps are mounted on sockets so you can upgrade them (probably will be worth doing).
Finally the box is much nicer than mine!
Location: London
Posts: 182
I'm Greg.
In terms of my own project, I got distracted recently. Mainly because of the Burson V6 playing now in my Whammy head amp.
This led to many hours of headphone listening using the dac described here but also to my vintage Philips TDA1541 CD player with DIY Pass D1 IV converter - very analogue sound! I guess when the dac is finished I will have to build a balanced D1 IV stage for it.
Being distracted by the headphone listening I ordered PCBs for yet another head phone amp... Pioneer Super Linear by EUVL from diyaudio.
Location: London/Durham
Posts: 6,878
I'm Lawrence.
I thought you got the boards free and used an old case? It's nice to build something yourself anyway I wish I could!
I think I got a good deal. It sounded a bit bass light with the USB direct so I used my JKenny USB-S/PDIF convertor and it sounds really good now
I like the 2 filter option (fast or slow) but I'm probably going to use the fast roll off one.
Fortunately I have 6x OPA234s from another dac I already upgraded that cost me £150 so no extra expense there
Last edited by Lawrence001; 30-01-2020 at 23:06.
Location: London
Posts: 182
I'm Greg.
Yes, the board was free but without the dac chip. That alone is £55 for a private customer.
And then all the bits and pieces. I also bought the BusPirate (£30) to debug this particular board.
As for the op amps: The annoying thing is that you need 6 singles while 3 doubles would be almost half the price.
Having singles is probably marginally better in terms of separation.
I would prefer to spend the same amount of money on 3 doubles than 6 singles. I am pretty sure the result would be better.
Location: London
Posts: 182
I'm Greg.
Yesterday I have done some dreaded mechanical work related to the screen. It looks actually better in real life than on those pictures. Maybe some flakes of polyester need to be sanded off.
The lines are straight.
The actual screen is sandwiched between the front plate and the old pcb and fixed with 3 distance screws. 2 screws are glued to the front plate, 1 to the pcb.
Location: London
Posts: 182
I'm Greg.
Got distracted by tinkering with my Whammy and Zen headphone amplifiers. So not much progress here (except the the present DAC is used daily in combination with the aforementioned amps).
Ah! Settled for Lt3045 preregulated by LM317 for the AVCC. I guess the diff compared to my previous experiments with similar (and more potent) LT3045 is that a small PCB with lt3042 is mounted directly on the DAC AVCC input. I guess distance matters!
Location: London
Posts: 182
I'm Greg.
Still working on the window for the Led screen. Already on the third version. This one is passable. I did not take pics of the failed approaches. If I am happy with the present one I will make some pics tomorrow.
Otherwise listening to the dac pretty often.
Location: London
Posts: 182
I'm Greg.
As promised some pics of the screen window.
The first attempt was just a simple rectangular window. I could not figure out how to glue it nicely.
So the second one was a rectangular piece of transparent plastic but, I routed a small lip around it. The idea was that I will glue it from the outside and the lip will rest on the front panel.
I used a speaker surround glue which dries transparent. Still it did not dry nicely and I did not like the result.
Notice my great gluing weight!
Location: London
Posts: 182
I'm Greg.
Not liking the previous result I went for a simple solution. An aluminium frame which covers the joint between the front panel and the window.
The transparent plastic has been glued to the alu frame from the inside.
One pic shows the result before cleaning the excess of the glue.
You can see a blob/stain on the screen - this is the protective foil which I haven't removed yet.