D1 I/V Stage Finished.

[Jaap]

CS4398

I have a cs 4398 dac

Any suggestions what to put after it (to replace opamps) ?

 

[00940]

the CS4398 also performs I/V inside the chip. The opamps afterwards are a filter, not a I/V stage. Stick a bozoz if you want afterwards.

 

[Cobra2]

D1 I/V

I have just tried the D1 I/V on my Parasound DAC-1000.
But I have some background-noise...
PSU? (promitheus' kit).
Or is it the I/V stage itself?

Arne K

 

[DragonMaster]

Hi, still not built.

One thing I'd like to know, does it have sin(x)/x compensation? I'd just like to know if I should put Pedja's filter(He posted on his group a week ago) or not if I use the D1.

 

[elviukai]

hi everyone, how the d1 stage? I have parasound dac 1500. looks like it is VERY similar to pass labs d1-similar receiver, digital filter, DAC chips. except analog stage. there are lot of analog devices opa, lot of black gates = very long signal path. the sound is very warmth and analogic but it is not ultimately dynamic and soundstage seems not the best I have ever heard. it is very well built with very good parts, but seems need new analog stage I am absolutely newbie on digital. here is the spec of my dac- cs
four bur brown pcm 63p-k highest grade dac push-pull for each cannel and fully balanced. dac has about 110 000uf PS, 9 diferent power suplies , 3 transformers and etc. I wonder is it posible to convert it to exact pass labs dac. transformers are 2x12, also 2x21.7 and again 2x 21.7V

 

[spencer]

Hello,

I just try the D1 Jfet IV in attached diagram. The sound is really good on my PCM63 DAC. The offset at input is also more stable (easy) to adjust compare to original D1.

Spencer

 

[spencer]

Here is the photo.

Spencer

 

[spencer]

Further improvement with K389BL at input and parallel K170 in source follower attached.

 

[spencer]

Updated circuit attached.

 

[Ruach]

Hi Spencer,

I am not too familiar with the transistors. Are you using the 2SK170, 2SJ74 for your circuit.

What is K389BL? I am not able to locate a datasheet for the K389BL.

Your DAC looks like a Lite DAC50. Did you buy it in Hong Kong?

Thanks

 

[spencer]

Hi,

Yes I use 2sk170BL and 2sj74V.

2sk389 data sheet refer to http://www.datasheetcatalog.com/catalog/p51240.shtml

Note two matched 2sk170 = 2sk389.

389 is too expensive to get and 170 is still available at reasonable price.

Last month I am able to find 2sk170BL in YH - Sim Lim Tower basement but now all sold out at 0.8 per. Luckily I can now easily find in ShenZhen electronic market at half price but min 200 pcs one bag. I think YH still have 2sJ74V.

Regards,
Spencer

 

[spencer]

Yes, my dac is Lite DAC50 which is the last demo set I brought in Shenzhen agent. I think the only way is to get direct from Guangzhou Lite now. It is still hard to find as the dac PCM63 is almost not available in the market.

 

[Ruach]

Thanks Spencer. I will check out YH over the weekend.

What is the change in the performance of the Lite DAC50 when you removed the passive I/V and tube buffer to replace them with the JFET I/V?

Can I have your email so that we can take the discussions about the DAC50 offline? Thanks

 

[spencer]

Original tube I/V is just average performance, Russian tube sound like no imaging and poor resolution. Use Nelson Pass I/V is two levels up, Jfet is even better on high frequency. You must try before you can believe. In simple term, well design discrete I/V is much better than Op-amp or tube.

Note the original power supply layout on the DAC is also no good. Need to ensure there is a CLC for each supplier pin/voltage of each PCM63. Thus total use 8 CLC from the two regulators on +/- 5V.

I also put 10uF MLCC capacitors in parallel with Tantanum cap solder direct from DAC supply pin to ground.

All receive IC and DF IC also need better power supply decoupling by MLCC.

 

[spencer]

skcheung68@hotmail.com

 

[Ruach]

Thanks Spencer for your comments.

I am sourcing for a set of Lite DAC50. I hope to use it for my experimentations with the D1 I/V as well as the Jfet I/V stages.

I may add in a passive preamp stage into the DAC50 based on the passive transformer circuitry.

 

[spencer]

I pay 1700 rmb for the set which I feel is too expensive. If you can get the chip PCM63, buy a kit pcb will only cost you total about 1000 rmb.

 

[Ruach]

Hi Spencer, 1700 rmb is considered cheap to some of our forumers here

I do not know where to find the kit set and you are right about the PCM63K chips. They are not easy to find. Monarchy does not sell new PCM63K anymore. They have pulls at US$25 each though.

I have sent you a mail.

Btw, fyi, the Monarchy M24 DAC is a Lite DAC50 on steroids

An externally hosted image should be here but it was not working when we last tested it.

 

[spencer]

In China, Purer is one of few guys selling pcb of different dac chips to make a low profit from diyers.

http://www.cndiyclub.com/bbs/thread.php?fid=32

The other guy Mr. Wang also sell pcb

http://www.cndiyshop.com/bbs/index.asp?boardid=5&page=

I hope you can read Chinese.

For PCM63PK, I am not sure if Guido Tent still selling in Europe at Euro 35 per. You can check.

Spencer

 

[spencer]

Sorry I dont receive your mail.