TDA1541A modification!!!! Best VFM mods

[UV101]

I have a philips CD960 (TDA1541 and CDM1 Transport)which has had a serious amount of work carried out on it.

The whole PSU has been reworked along with the dac, clocking and output stage.

I recently purchased a couple of Meridian 207's and have been playing a little and working on trying to see what actual mods represented best vfm and gave me the most gains.

I'm happy to discuss my findings here and listen to any idea's on some possible quick wins on this truely awesome and analogue sounding multi bit dac

Being new here, i'm interested in finding out who knows of/ likes/ loves with a passion this awesome DAC chip :)

[leo]

I've tried a few diy dacs using this chip with various output stages, it remains one of my favourites and was used in the first diy dac I built after playing about with various CDP's which used it.

These are the ones I've tried so far

1 x TDA1541A + classic op-amp I/V
1 x TDA1541A + passive I/V into ECC88
1 x TDA1541A + passive I/V into 6C45PI
2 x TDA1541A + passive I/V into 6C45PI
1 x TDA1541A + Pass D1 I/V
1 x TDA1541A + discrete no feedback I/V
1 x TDA1541A + common base I/V

Various regulation from very simple shunt and filtered zener reference into Darlingtons also ALW to Teddy regs.
DEM filter and a few Asynchronous reclockers as well as straight I2S .
So far I've found I prefer single TDA1541A into suitable output stage over parallel dacs

Best value mods? sort out the regulation, decoupling and grounding.
Ditch the classic Op-amp I/V stage, their shite with this dac no matter what fancy chip you use imo, go with a no feedback design if you can, a few op-amps will also allow this, add a nulling circuit on the dacs output so the TDA's output pins see's 0v DC.
Try sticking a low ESR low leakage cap from the -5v to the -15v, tweak the regulation so theres as near to 10v across those pins as you can get

[DSJR]

An Arcam engineer told me that the digital filter was more important than the dac chip itself (when the "crown" version first appeared).

The audio stage feeding the amp is where I'd look and maybe this is what's been mentioned above...

[UV101]

I'd say sorting the power supply for the filter chip was the biggest single improvement you can make to these players for sure.

IMHO people side step the issue when they go NOS. Instead of nursing and coaxing the awesomeness from the filter, they just remove it from the I2S bus. The problem is that normally they leave the clocking distribution to the filter even tho its no longer in the digital chain. The filter still polutes the 5v supply rail. If you want to try NOS, you should remove the filter chip completely, move the clock to the decoder and sort out the digital muting.

as I've said, I prefer to ustilise the OS filter chip so......

The 1st thing I did in the virgin Meridian 207 was to hook pin 28 (+5v) out of the socket and give it its own low noise regulator and hook on some better local decoupling. Masive massive improvement. ;)