D1 I/V Stage Finished.

[stueyh]

Can the D1 be used with PWM dacs? Im specifically thinking the marantz CD63.

 

[bou]

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.

 

[jonclancy]

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

 

[promitheus]

Hi Jon,

this part from bourns fits.
Bourns 3266W 1/4" trimmer.
see data sheet.
for instance RS online number 521-9259

 

[jameshillj]

... 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!

 

[jonclancy]

Thanks very much, Prom.

Much appreciated!!

Jon

 

[mat_one]

i gonna built this stage, but i don`t know if both transistors per channel should be matched?

 

[luvdunhill]

I was wondering if there are any PCBs available for the D1 I/V stage (or any other NP digital related projects)?

 

[ctong]

How is the value of C40 (0.01u) determined?

 

[regal]

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 ?

 

[relder]

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 ?

The buffers are the output FETs, Q2 and Q5. No inductors, but there are some caps there for a filter.

 

[ctong]

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?

 

[vzs]

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

 

[vzs]

Moved my question to this newer thread: link.
Sorry for confusion, Zsolt