Marantz CD-50 and CD-60, TDA1541, CDM4/19 - Page 61 - diyAudio
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Old 18th February 2012, 05:08 PM   #601
GoranB is offline GoranB  Poland
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Quote:
Originally Posted by danico View Post
Hello Mayday!

Good to see your experiment with your player.
I have a cd-40 that modified a half year ago. It's just sound incredible good.
Now I listen with an Infinity Qa speaker with EMIT tweeter, just superb detailed and transparent with a lots of air.
Super in every way.
Never go back for normal speaker that for sure.
I read ecdesign's treat all over and tried some of his circuit.

You should try the reg for the 1541 its cheap to build and worth a lot!! clean power very important!

there is an easy way of DEM sync with the WS signal. used with the I2S attenuator.
The wima caps not the best solution and after the I2S att. is not needed at all.
Here is a part from the DEM clock from ecdeign:

"The DEM clock needs to have low jitter and induce lowest possible crosstalk. The problem is that the DEM clock needs to be injected in an on-chip oscillator that must not be allowed to oscillate.

The DEM clock has direct effect on the bit errors of the 6 MSBs in the TDA1541A, and on-chip crosstalk (inter modulation between DEM clock and other on-chip clocks) thats why there are clearly audible differences between DEM clock circuits.

I noticed that the indicated 200KHz DEM clock causes a number of issues like problems with active divider settling time, crosstalk with on-chip clock signals, ground-bounce, and problems with external decoupling film caps (inductance).

Other problems are the extra divider and inverter required to derive the DEM clocks that add jitter (every logic element adds jitter). The DEM clock distribution among multiple TDA1541A chips is also problematic.

So I tried to design a simple but highly effective DEM clock injection circuit that uses one of the local I2S signals.

After some experimenting I decided to use the WS signal (44.1 KHz). Decoupling cap value can be increased to approx. 400nF (390nF) in order to achieve similar filter characteristics although 100nF worked fine too.

WS was connected to the anode of a Schottky diode, the cathode was connected to a resistor of exactly 13K, and the resistor was connected to pin 16. Pin 17 was left unconnected.

The value of 13K corresponds with a WS signal amplitude of exactly 3.3V (SD-transport I2S output level). The value needs to be increased to 14 ... 15K when when using 5V signal level. The value of the resistor is critical, too high tolerance will prevent the on-chip DEM clock from tracking. This method uses current steering, so the current deviations must be tuned in such way that the DEM oscillator tracks reliably."

I hope you find it useful. I know its a long way to achieve our goal.
Your board looks similar to me
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Old 18th February 2012, 07:23 PM   #602
Mayday is offline Mayday  Sweden
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Quote:
Originally Posted by josha View Post
I haven't tried the shunt regs yet - too busy listening to it ;o) I was considering having a go with the TL431's as per TNT Audio but work keeps getting in the way of all my fun!

How hot does that regulator get? Too hot for 'hot melt glue'?
I don't know yet, but I guess it runs rather hot. UV101 and Andrew recommended large heatsink for it.
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Old 18th February 2012, 09:17 PM   #603
josha is offline josha  United Kingdom
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It does indeed get hot but I'm suggesting keeping you're existing PSU and heatsink (altered to supply 7v) then regulating again, locally, down to the 5v required by the 7220. I don't know if the local regulator would still need a heatsink as I've only tried this on the 1541. It would help, of course, if I really understood these things!
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Old 18th February 2012, 09:25 PM   #604
Mayday is offline Mayday  Sweden
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Quote:
Originally Posted by josha View Post
It does indeed get hot but I'm suggesting keeping you're existing PSU and heatsink (altered to supply 7v) then regulating again, locally, down to the 5v required by the 7220. I don't know if the local regulator would still need a heatsink as I've only tried this on the 1541. It would help, of course, if I really understood these things!
I don't think it matters that much if I take Vin to the 7805 from Vin from the original 7805 or from Vout from a 7807. I'm thinking it's the almost 200mA that makes the reg for the SAA7220 hot. Just what I think...not gospel.

I'm thinking I can fixate the regs with non-conductive silicone. The type used as a sealant(spelling)? In engines. I should have some at home.
It hardens to a firm rubbery consistence. I could also use this to fixate the SAA7220 reg on the pcb by laying it on it's back, heatsink down. There's plenty of empty space near the SAA7220 to do this.
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Old 19th February 2012, 06:00 AM   #605
GoranB is offline GoranB  Poland
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Modified cd 40
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Old 19th February 2012, 07:10 AM   #606
GoranB is offline GoranB  Poland
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To achieve better sound i recommend a separate PSU for TDA1541 and SAA7220.
Here is a PS board for TDA1541
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Old 19th February 2012, 09:41 AM   #607
Mayday is offline Mayday  Sweden
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Nice work Goran!

Very extensive modification by the looks of it
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Old 19th February 2012, 11:19 AM   #608
GoranB is offline GoranB  Poland
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Quote:
Originally Posted by Mayday View Post
Nice work Goran!

Very extensive modification by the looks of it
Thanks

It was really fun to make all those mods and it was worth. Doesnt look nice but sounds really good.
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Old 19th February 2012, 03:46 PM   #609
Mayday is offline Mayday  Sweden
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I think it looks nice. You should see some of the stuff I built before I met my fiance and had to consider the safety of our big and curious dobermann.
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Old 23rd February 2012, 10:54 AM   #610
Mayday is offline Mayday  Sweden
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These projects have to wait now. Had to take our dobermann to the vet. and the bill was rather high so that's where $$$ will be spent for a while.
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