DEM reclock with TDA1540

fvale · 27th February 2011, 04:56 PM

Did someone succesfully implement DEM reclock with old TDA1540 dac?

oshifis · 3rd March 2011, 01:18 PM

I've just done latch signal (LE) reclockig, but I think DEM reclocking can be implemented the same way as with the TDA1541A. As for the latter, I coupled the Q and Q! outputs of a 74HCT74 to the DEM pins with 1nF capacitors each. The flipflop divided the master clock to 705.6 kHz (/16 division from 4.2366 MHz). It worked. I want to experiment with transformer coupling, instead of capacitor coupling.

fvale · 3rd March 2011, 01:45 PM

are you talking about LE reclocking between SAA7000 and TDA1540?
I haven't been able to get it working. Anyway, incredible, just today I was able reclock the DEM with the 1540. I use the dc coupled ECdesigns schematic with an about 1MHz signal (BCK, Q and /Q, obviously). I had to use four diodes (I think ECdesigns suggested this for multiple 1541 setups), 2K2 from the DEM pins to -17V and 15K. With scope waveforms are not as clean as with original capacitors, but it sounds excellent! I also listened to a -40db, or so, recording and it's ok. When I'll have finished last fine trim I will post final resistor value.

Last thing, Q and /Q signals can be supplied randomly on the DEM pins, or there's an order?

oshifis · 3rd March 2011, 02:33 PM

I did LE reclocking as per the attached PDF.
I think Q or Q/ to which pins is not important,

27th February 2011, 04:56 PM	#1
fvale diyAudio Member Join Date: Jan 2006 Location: italy	DEM reclock with TDA1540 Did someone succesfully implement DEM reclock with old TDA1540 dac?

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
TDA1541 DEM reclocking	rbroer	Digital Line Level	241	29th October 2011 07:32 PM
Philips 304 mods. Tda1540 to Tda 1541 and DEM RECLOCKING	Maurizio	Digital Line Level	3	18th November 2010 09:44 AM
TDA1540 decoupling caps	wutzke	Digital Source	5	27th August 2010 10:52 AM
From TDA1540 to TDA1541	D.A.R.R.Y.L.	Digital Source	21	18th November 2009 11:51 AM
TDA1540 passive I/U Stage ???	caine28	Digital Source	8	28th December 2008 10:32 PM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read


	Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving

3rd March 2011, 01:18 PM	#2
oshifis diyAudio Member Join Date: Mar 2004 Location: Budapest, Hungary	I've just done latch signal (LE) reclockig, but I think DEM reclocking can be implemented the same way as with the TDA1541A. As for the latter, I coupled the Q and Q! outputs of a 74HCT74 to the DEM pins with 1nF capacitors each. The flipflop divided the master clock to 705.6 kHz (/16 division from 4.2366 MHz). It worked. I want to experiment with transformer coupling, instead of capacitor coupling.

3rd March 2011, 01:45 PM	#3
fvale diyAudio Member Join Date: Jan 2006 Location: italy	are you talking about LE reclocking between SAA7000 and TDA1540? I haven't been able to get it working. Anyway, incredible, just today I was able reclock the DEM with the 1540. I use the dc coupled ECdesigns schematic with an about 1MHz signal (BCK, Q and /Q, obviously). I had to use four diodes (I think ECdesigns suggested this for multiple 1541 setups), 2K2 from the DEM pins to -17V and 15K. With scope waveforms are not as clean as with original capacitors, but it sounds excellent! I also listened to a -40db, or so, recording and it's ok. When I'll have finished last fine trim I will post final resistor value. Last thing, Q and /Q signals can be supplied randomly on the DEM pins, or there's an order?

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)