Wolfson WM8805 I2S to TDA1541A NOS

[nimo_jon]

Wolfson WM8805 I2S to TDA1541A NOS

Much has been talked about the CS8414 receiver feeding the TDA1541A. Many thanks to ECDESIGN and others who has shared so much about optimizing the NOS TDA1541A.

There is a kit that utilizes the Wolfson WM8805 high performance S/PDIF transceiver.
This receiver provides low jitter recovery of S/PDIF supplied master clocks. That sounds good.
I built the kit and it was not choosy on the quality of transport, whether it was an expensive Denon SACD or a plain jane Pioneer DVD player.

You can find this DAC kit from Ebay; just do a search on WM8805 NOS.
One word of caution is the built quality of this kit is not top notch.
There could be some odd solder joints.

The 12Mhz crystal provides a reference clock for the phase lock loop in the WM8805.
The quality of the reference clock has great impact on the sound quality, even though it is not the master.
A simple solution is to give the TCXO a dedicated power supply and wave shaping using TTL.



Here is the circuit diagram of the micro-controller selecting the input of Coaxial, Toslink or USB input for the WM8805.
You can also select 16 Bit I2S or other modes.
I am not using USB in the stereo, so I removed the USB interface to minimize interference.



I had a lot difficulties to have the DEM circuit work.
Syn the DEM to WS derived from master clock worked.
I biased pin 16 to -15V using a 6V2 zener and ac coupled the signal.
This was the only way to get it to work.



This is the main board with heavy gauge copper.



The I2S attenuation and latch was done on separate perf boards.
For the I2S attenuation, using only 3uH per arm gave good results.



This board in stock form, a S1 crown 'appeared' to have better depth and focus than using a standard TD1541A.



However, certainly female vocals can sound piercing and unbearable. (therefore the seller offers a HDAM unit, which is a discrete buffer.
The discrete buffer has a certain amount of attenuation at HF, thereby covering up the offensive HF performance.)
This is certainly an undesirable phenomenon when operating in OS mode.
I have verified that installing I2S attenuation solves this issue. (Ground bounce?)



Somehow, after the mod, the standard TDA1541A at the top picture sound as good as the S1 crown chip. (FAKE Crown ? or the circuit is getting the TDA1541 work as designed.)

I am using the AD744 as the output buffer.
I have been using the AD744 with AD811 aka Walt Jung's trans impedance DC coupled pre-amp since my early Audio Amateurs days.



This stage is really up to individual's taste.
There are certainly alternative op-amps which others would prefer.
Personally, I find the AD744 detailed and musical in this setup.

At the end of the day, it is the music that we are after.
Never mind what the LeCroy scope says, if it sounds boring, it is boring.



For years I have used this CD as a stringent test for many systems:
Harp Concertos by Marisa Robles (Nov-1990, London)

The harp can sound very muffled and vague, with no apparent imaging even on some very $$$$ setup.
But with the DAC, I can almost 'see' the harp right in front of me now.

Another good test CD on musicality is:
QUARTETTO ITALIANO DEBUSSY & RAVEL STRING QUARTETS

The ECDESIGN mods will make the DAC very revealing and yet very musical. Thank you ECDESIGN.

I really enjoy this DAC now, and hope you share the joy I have.
Cheers.

[shooter]

Nimo_jon,
Can you post your latch circuit, I have purchase the WM8805 multiple input to spdif board from the same seller, and try to use the i2s out directly to my TDA1541 dac, and got a lot of noise from direct connection.
Thanks

[nimo_jon]

Hi there

This is the latest simple DEM/Atten circuit for the WM8805. It is very simple and sounds awesome. Imaging is deep and musicality is involving.

Using a clocked latch (master clock from WM8805) did not sound as good as buffering the I2S lines. I suspect I added more jitter.

The clock feeding WM8805 has to be very stable. See the 74HC04 circuit attached.

The power supply for the I2S buffer and attenuation is provided by a separate LM317T adequately bypassed at the +5 output.

DEM is directly adopted from Grundig. Surprisingly this sounds better than any other setup I tried.

[nimo_jon]

I mentioned before the build quality of this kit is not very good. Therefore, it is good to check the functionality of this kit before any work is carried out. When I first powered up the kit, the +5 volt regulator had some cold joints somewhere. Redoing the joints near the +5 regulator solved the problem. Having said that this is a fairly bomb proof kit that can withstand a lot of abuse.

[shooter]

Thank you for the reply, I will try your circuit in my dac.

[nimo_jon]

Hi there

Any joy yet?

FYI I only use the optical link. Apparently there are some noise when using coaxial cable. Also, the DAC will sound horrible when you choose 16bit Right. So you have to use 16bit I2S indicated by D1 D2 both lighted up. Cheers.

[shooter]

Not yet, just order parts, and thanks for the heads up.

[jean-paul]

Hi, I bought some of these separate SPDIF modules with WM8805 for projects but I have my doubts about the 12 MHz oscillator being fed with 5V. IMO that should be 3.3V. What do you think of that ?

[nimo_jon]

Hello

To be honest, I have no idea. There are no part numbers on the original TCXO.

I set aside the original TCXO that came with the kit. Although Wolfson data sheet mentions the internal Phase Lock Loop may allow the use of a cheap external crystal, it is imperative to use a high quality clock to get a decent sound.

I power a separately purchased 1ppm 12Mhz TCXO using a separate transformer, LM317T, adequate filtering, and a small inductance feeding it at 5V. Buffered thru Schmitt trigger using 74F TTL feeding the Wolfson, I can hear a distinctive improvement on sound quality. The definition, details and sound stage improved while the highs are more airy and smooth. Changing back to the standard TCXO (also at 5V) the sound became thinner and less refined. It was pretty obvious so I have no intention to bring back the original TCXO.

I have not tried 3.3V on the original TCXO. There is a 3,3V provision for the Wolfson, perhaps tapping that power can confirm if the TCXO needs to run at 3,3V?

regards

Jonathan

[jean-paul]

The datasheet of the WM8805 says that max. input voltage of the XI input can be DVDD + 0.3V. DVDD is max. 5V but recommended is 3.3V so that is why I think 5V is not OK. It could be that the XI input is overdriven like this.

Which brand and type TCXO did you use ?