Has anybody used the D1 I/V with the PCM1794a in mono mode? If yes, did you connect IL+ with IR- and IL- with IR+?? I am building a DAC with 2 PCM1794a in mono mode and I would like to use the D1 I/V stage instead of op amp.
A couple of questions.......
Hi Guys,
I'm in the middle of assembling my D1 (thanks Prom!), but have a couple of questions:
1. Does anyone have a part number for the 20K multiturn trimmer to fit the parts overlay/footprint on the PCB?
2. How much current does the D1 draw? I saw 20mA per channel in another thread. I'd like to have a look at a superregulated power supply if the draw is light enough.
Many thanks in advance for your thoughts......
Cheers
Jon
Hi Guys,
I'm in the middle of assembling my D1 (thanks Prom!), but have a couple of questions:
1. Does anyone have a part number for the 20K multiturn trimmer to fit the parts overlay/footprint on the PCB?
2. How much current does the D1 draw? I saw 20mA per channel in another thread. I'd like to have a look at a superregulated power supply if the draw is light enough.
Many thanks in advance for your thoughts......
Cheers
Jon
Hi Jon,
this part from bourns fits.
Bourns 3266W 1/4" trimmer.
see data sheet.
for instance RS online number 521-9259
this part from bourns fits.
Bourns 3266W 1/4" trimmer.
see data sheet.
for instance RS online number 521-9259
... and I would seriously consider a supply that starts with smaller ripple caps into a C-multiplier (like Mr Evil's) onto an active current source to finish with a shunt reg - sounds quite a mess, but it's three seperate simple building blocks that are quite simple and have appeared here often. Curiously, you can "vary the sound" of these "blocks" quite a bit without having any of that instability problems of many series reg feedback designs - good fun!
I was wondering if there are any PCBs available for the D1 I/V stage (or any other NP digital related projects)?
So with this D1 I/V do you still need a buffer?
Also in this thread it is mentioned that there is a first order filter, I don't see an inductor anywhere so I assume this is separate ?
Also in this thread it is mentioned that there is a first order filter, I don't see an inductor anywhere so I assume this is separate ?
regal said:
The buffers are the output FETs, Q2 and Q5. No inductors, but there are some caps there for a filter.
Has anyone compared this version of the Jfet D1 analog stage
http://www.diyaudio.com/forums/showthread.php?postid=616248#post616248
with Spencer's? The parallel Jfets reduces the voltage variations at the DAC output and presumably allow the DAC to work better. Spencer also had a hand drawn schematic using parallel Jfets but apparently discarded it later. Any comments?
http://www.diyaudio.com/forums/showthread.php?postid=616248#post616248
with Spencer's? The parallel Jfets reduces the voltage variations at the DAC output and presumably allow the DAC to work better. Spencer also had a hand drawn schematic using parallel Jfets but apparently discarded it later. Any comments?
Input voltage swing
Hi! Seems that I'm a latecomer here but hopefully you guys who have built this can help out.
I just finished my take on a D1 I/V based on the original? (post #26) schematics but didn't connected to my AD1865 yet as I'm not sure it is all right as it is.
I noticed two things while adjusting the input voltages for 0V:
1. The input is slowly rising to around +50mV as it warms up. After 10mins T2 warms up to ~50C while T1 stays ~30-40C, so wouldn't normally need a heat-sink but I can mount one. I expect that with a heat-sink it will settle ~10-20mV.
2. On powering up both inputs are at about -3.2V, quickly go down to 1V then 100mV in about 10sec, to 50mV in 30sec and as T1 is warming up it reaches 0V in 2-3min and very slowly rising after. Without heat-sink it probably goes up to +50mV.
- Is this the expected behavior of how this circuit should work?
- Wouldn't that startup voltage swing damage the DAC chip?
- 50mV DC on input is within limits or should I add a heat-sink to keep it lower?
Many thanks,
Zsolt
Hi! Seems that I'm a latecomer here but hopefully you guys who have built this can help out.
I just finished my take on a D1 I/V based on the original? (post #26) schematics but didn't connected to my AD1865 yet as I'm not sure it is all right as it is.
I noticed two things while adjusting the input voltages for 0V:
1. The input is slowly rising to around +50mV as it warms up. After 10mins T2 warms up to ~50C while T1 stays ~30-40C, so wouldn't normally need a heat-sink but I can mount one. I expect that with a heat-sink it will settle ~10-20mV.
2. On powering up both inputs are at about -3.2V, quickly go down to 1V then 100mV in about 10sec, to 50mV in 30sec and as T1 is warming up it reaches 0V in 2-3min and very slowly rising after. Without heat-sink it probably goes up to +50mV.
- Is this the expected behavior of how this circuit should work?
- Wouldn't that startup voltage swing damage the DAC chip?
- 50mV DC on input is within limits or should I add a heat-sink to keep it lower?
Many thanks,
Zsolt
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