DAC with Four PCM 1704, PMD100, CS8412

[Extreme_Boky]

1. check Figure 4, chose any high quality pulse transformer with appropriate "amplification"

2. read about transmission lines.... and importance of proper impedance matching. you'll figure-out that two sources connected in parallel on spdif line is really bad idea.

 

[gabrielbecheanu]

Extreme_Boky this DAC with i will receive it soon has this digital input:

- AES/EBU : discrete lvds translator - 192/24
- S/PDIF : discrete lvds translator - 192/24
- USB : asynchronous, FX2LP interface – 192/24*
- I2S over HDMI (native LVDS or CMOS) – 192/24
*drivers available for Win,Mac, Linux

I have two sources
1 Dune HD max with S/PDIF coaxial and optical outputs
2 CD player Onkyo with optical output

I want to connect those two to the DAC HD max via S/PDIF coaxial and my CD player via AES/EBU the sources i will change them from the DAC using a remote control.
I want to modify my CD player and put an XLR connector but i must convert S/PDIF to AES/EBU. Some people say that an 74H will do the job but i don`t have a diagram for that.
I don't want to use two sources in parallel on on S/PDIF input
Thanks for the pdf very useful
Best regards

 

[gabrielbecheanu]

Hi
I found something
SESCOM SES-AES-EBU-2 75 Ohm BNC Female In to 110 Ohm Male XLR Out AES/EBU Impedance Transformer | Location Sound Corp.
Any one use something like this?
Best regards

 

[Extreme_Boky]

see attached, page 3

Boky

 

[gabrielbecheanu]

My DAC arrived today, I make some photos and I hope to use it as soon as possible, I will tray a few IV stage with transistors and Tubes, I like the way is made but the most interesting part in my opinion is the input stage of the DAC using a SPARTAN chip like in the new Accuphase DAC DC-901.

A few years ago I listen a WADIA 861, I was impress and start to read about it, this PCM 1704 was always in my mind but never thought that I will have a quad PCM 1704 DAC like in WADIA but with all this inputs and future for HD 24/192 files.
I will inform you guy about it, hope to be the best DAC for me and never think about for another upgrade.

My brother use a Buffalo DAC and I am very curious to make an A/B test.
Some say that the ESS SABRE 9018 is the best DAC at the moment, will see.

 

[blues 66]

Hello, Gabriel Hello, sorry for my English, there is no possibility to buy less?
475 euro are so many.
currently use a converter commercial YBA WD 202 which mounts fully symmetrical design based on Texas Instruments' PCM1796 BB texas instrument Converter and Audio codec, and the sound is very nice ...
But I would like to sell it and buy:
* CHIP card DAC 1704, transformers and all the separate components, for aurtocostruirlo

is possible and where?

thanks
good continuation

 

[gabrielbecheanu]

PCM 1704

Hi
The DAC has this price because the convertors are expansive
Check at Farnell to see the price. Componenti elettronici | Parti elettroniche | Farnell Italia

A few days ago I start my DAC and I use a I/V from Twisted Pear The IVY Balanced Line Stage

But this is made for ESS not for PCM
The sound is good but the amplification factor is low, I will make soon the I/V stage by EUVL from this forum with JFET 2SK170. I have a feeling that will be the best I/V for PCM 1704 and I will try to make from balanced to SE whit a BCF from AIKIDO
I always want to have a DAC with 4xPCM1704 for HD 24/192 files so this is the only one.

Best regards and Marry Christmas

 

[blues 66]

Hello Gabriel, I'm sorry for the delay of Merry Christmas ...
Coming to us:
Thanks for the link, as you may not know, I am a Newbie ... and I'm taking or better looking, more material available for the DIY (which, in fact I am not able, I apologize) ... Anyway I have a friend capable in DIY!
Question "?"
The DAC 1704, works in current or voltage?
because if it is live, it would be easier, leaving the full range of risk factors, using the power!

I know it would be a 'heresy, and I apologize for my question;
Ma would be silly to try, material Chinese / Korean cards already assembled,
the bay? Card already ready?
possibly chip which would be appropriate for the USB output?
a TE7022

Thanks Merry Christmas

 

[gabrielbecheanu]

Hi
I'm not an expert in digital but PCM1704 is a current DAC so if the I/V is good you will have o good sound. I use before a Chinese DAC with CS4398 but I can` t compare them, this DAC RD30 is something else much better.
Some time the money you pay shows you the quality of the products.
If you check on the internet who use this DAC before in their products you will see how much they cost, I don`t think you will find a CD under 3k USD

 

[stephensank]

IMO, you are absolutely wasting your PCM1704's if you use i/v, lpf or output stages that have loop feedback. I've done my Pioneer DV-AX10(differential 1704's, SM5847 DF) with passive resistor i/v, followed by discrete jfet voltage gain and current amp stages(ample current to directly drive inefficient Yamaha orthodynamic headphones beautifully) of my own design, and it is absolutely spectacular.

 

[abraxalito]

IME (not directly with PCM1704, but other multibits) its not so much feedback vs non-feedback rather HF linearity which matters most. A passive LPF is a worthwhile introduction which proved to me that, prior to including it, my I/V and post-amp performance was still limited by HF non-linearities. Yes, a discrete design is certainly one way to get the necessarily linearity, but its not the only way.

 

[stephensank]

If you are familiar with the rationale behind zero-feedback amp designs, you'll have an easier time getting what I think about this. With, e.g. typical active iv converters, you have very high level feedback around an opamp(chip or discrete matters not). Because there is a small but finite time required for the signal to go through the opamp, what is fed back to input is a delayed signal, which works just fine for sinewaves & other non-repetitive waveforms, but fails to do as intended for non-repetitive waves like music, and rather creates new distortion components(generally at a much lower level than the distortion it's intended to cancel in a well designed feedback amp stage, but real). Now think about how significant that time delay becomes to the gltch pulses & other digital artifacts coming out of the dac chip. The most telling thing about this to me, in my experiments with removing feedback completely from everything after the dac chip, is that the sonic effects of jitter become very, very, very nearly inaudible on a ladder dac when feedback is eliminated, and are hugely reduced on bitstream dacs. Even comparing a top shelf transport, e.g., and upgraded Museatex C-Lock CDD, to a very crappy dvd player as transport(e.g., Pioneer DV505), even my young, female, sound engineer assistant had a very, very hard time picking out any differences between transports, in the first trials using a Pioneer DV-S9(in dac mode, whether set to internal or external clock) rebuilt with my no-feedback, high current drive output stages after it's PCM1702's. My other DV-S9, upgraded identically, but with it's conventional(but also upgraded) iv & output stages, made it quite easy & obvious to hear which was the better transport. With ladder dacs, the only potential damage, as I can see it, that jitter can manifest in the output signal is in the nature of the glitch/noise spectra, exactly where feedback will have the most negative effect. Further, having zero feedback, combined with way overkill output current drive ability, has revealed to me nuances of tonal layering & sense of open space(and I don't mean just top end) that I had never heard before. Any other no feedback and/or passive iv designs that I have yet seen fail to address how mucn current it actually takes to drive a line, and a preamp/amp input, extremely well, which I think accounts for why such designs have not captured much attention in the market.

 

[abraxalito]

I get the independence of transport with my multibit DACs too. The transport I used did at first make a difference but that was caused by CM noise over the S/PDIF cable, not jitter. With the optimum routing of that input's grounding, transport dependencies have evaporated. For transport I'm using about the cheapest DVD player I could buy. I'm still using a feedback circuit after passive I/V. I don't buy the delay argument myself but I don't nowadays use normal opamps and certainly not any as active I/V. I get what you're saying about 'open space' - that came to my sound when I installed the passive LPF.

If you're experiencing what at first blush seem to be line driving issues, check that you're not getting CM noise back-injected into your DAC from the subsequent kit. Putting a CM choke in line might allow you to check to see if this is upsetting your SQ.

 

[regal]

I'm still using a feedback circuit after passive I/V. I don't buy the delay argument myself but I don't nowadays use normal opamps and certainly not any as active I/V .[/QUOTE]

or some reason passive I/V (with a cap) followed by an opamp gain (either discrete or IC+ filter + buffer)) sounds better to me than letting an opamp try to do the I/V conversion. Typically measures as good. I call it the passive I/V + phonostage. The cap + resistor prior to NFB Jefet gain just makes it work.Jim Hagerman I think was the first to come up with the idea

If you're experiencing what at first blush seem to be line driving issues, check that you're not getting CM noise back-injected into your DAC from the subsequent kit. Putting a CM choke in line might allow you to check to see if this is upsetting your SQ.

Find a transport designed by an RF engineer and 99% of transport "issues" go away. Can't help but think that noise on spdif is a bigger issue than jitter.

 

[abraxalito]

or some reason passive I/V (with a cap) followed by an opamp gain (either discrete or IC+ filter + buffer)) sounds better to me than letting an opamp try to do the I/V conversion. Typically measures as good.

I concur - and I think I know why. In making the measurement, I presume that's a THD+N measurement. But real music has lots of 'tones' - dense spectrum, with each individual freq at a much lower level. So IMD performance at much reduced signal level (say in the range -40 to -60dB) is the real issue for SQ, not THD at high level. Thus THD measures linearity in the wrong place on the transfer function. I reckon an opamp being used to do I/V isn't linear enough in that low signal range and we hear that non-linearity as 'greyness' and loss of soundstage depth. The best opamps for I/V are CFB topology and so I conclude the poor linearity is the LTP input stage primarily.

Find a transport designed by an RF engineer and 99% of transport "issues" go away. Can't help but think that noise on spdif is a bigger issue than jitter.

Agreed.

 

[fojica]

Hello Gabriel,

Did you manage to get any progress with RD30 dac ?
I'm looking forward to hear your impressions about it after some listening period.

Regards,
Tibi

 

[gabrielbecheanu]

Hi Tibi
As soon i will finish the Aikido Unbalancer as I/V stage i will post here my personal impressions.
Best regards

 

[gabrielbecheanu]

Hi
Today m manage to finish the Unbalancer, I made some measurements but the signal is to low about 362mV RMS so tomorrow I will made some modification, I will eliminate the negative feedback to see how high the signal will be, I want to have at the output 2V RMS. If I will not be satisfied I think I will order the I/V made especially for this DAC

 

[gabrielbecheanu]

Hi
I manage to finish the Unbalancer, now I have at output 2Vrms. At this point I made an A/B test between the DAC and my Dune HD MAX with has a AK4422 convertor
The differences are visible the sound coming from the RD30 is more precise more fluent more musical. Now I work at the case.
My dream comes true.
To have a 4xPCM1704 playing HD files is unbelievable. Most of the DAC made with this IC are made especially for 44.1 kHz sample rate and maximum 96 kHz but this RD30 can play 24/192 and 24/176 kHz without problems.
This DAC satisfy me. I will be glad to share with any one my experience with this DAC and the Unbalancer as I/V.
Maybe In the future I will order the I/V made for this DAC but because I use a tube amplifier I prefer to have also tube on I/V
Best regards

 

[charlesp210]

IMO, you are absolutely wasting your PCM1704's if you use i/v, lpf or output stages that have loop feedback. I've done my Pioneer DV-AX10(differential 1704's, SM5847 DF) with passive resistor i/v, followed by discrete jfet voltage gain and current amp stages(ample current to directly drive inefficient Yamaha orthodynamic headphones beautifully) of my own design, and it is absolutely spectacular.

Funny, according to Pioneer, the DV-AX10 uses Analog Devices multi-bit 192/24 converters (almost certainly sigma delta) not 1704's.

DV-AX10 - | Pioneer Electronics USA

I'm having very hard time finding out which converters used 1704's. Most I find mentioned actually don't. According to Stereophile the Mark Levinson 360 and 360S do:

Mark Levinson No.360 D/A converter | Stereophile.com

Also, the Wadia 861

http://www.stereophile.com/content/wadia-861-cd-player-specifications