Cambridge Audio 640P

ALBQ · 27th March 2008, 01:54 AM

Does anyone know where to find a schematic for a Cambridge Audio 640P phono preamplifier?

Thinking about modifying mine but, would like to understand the circuit in order to know what changes would make the most sense. There is a pretty long thread on Vinylengine but, no schematic. Any help is appreciated

Thank you - ALBQ

ALBQ · 30th March 2008, 01:05 PM

Cambridge Audio 640P - Update

Well, schematic or no, I took the plunge and installed gold plated sockets and OPA2134 OpAmps in the MM section yesterday.

Because of the type of solder used, getting the NE5532's out was a total pain but, the improvement in sound was more than worth it. Less congestion, greater space and better imaging yet, retains smoothness the 640P is known for.

Next step is to enjoy it for while as I research an input and output cap change - get rid of the electrolytics in the signal path

-ALBQ

sq225917 · 30th March 2008, 03:36 PM

http://media.bestkiteboarding.com/mm/640p.jpg

op637's on the gain stage and lm4562 on the Riaa

ALBQ · 30th March 2008, 10:48 PM

sq225917
I read your post on vinylengine – nice work. Any future plans or is it done?

Thank you for the advice -ALBQ

sq225917 · 14th April 2008, 03:34 PM

I think it's pretty much done to be honest. I am considering splitting the power supply off the PCB and putting it in all a full width case.

Maybe replace the regs with discreet units, not sure i need to probe their output noise first.

jpak · 22nd December 2009, 08:56 AM

Quote:

Originally Posted by sq225917

I think it's pretty much done to be honest. I am considering splitting the power supply off the PCB and putting it in all a full width case.

Maybe replace the regs with discreet units, not sure i need to probe their output noise first.

Has anyone looked underneath the metal enclosure labeled "discrete low noise MC stage"?

marco70 · 21st January 2010, 05:40 PM

Hi
link http://media.bestkiteboarding.com/mm/640p.jpg
doesn't work anymore or I'm doing something wrong ?
does someone have a working link / schematic ?
cheers

jacco vermeulen · 21st January 2010, 07:12 PM

Ca 640p

marco70 · 22nd January 2010, 02:06 PM

Many thx, next time I'm searching deeper in other threads :-)
cheers

sq225917 · 31st January 2010, 04:27 PM

Sorry guys I have to clean the worked served stuff out sometime. The vinylengine thread is the best reference, pages 28-29.

i do still have the 640p in a box somewhere, if someone wanted pics. I've done nothing to ti since, and to be honest KCS's version was taken much further than mine was.

27th March 2008, 01:54 AM	#1
ALBQ diyAudio Member Join Date: Dec 2003 Location: Albuquerque	Cambridge Audio 640P Does anyone know where to find a schematic for a Cambridge Audio 640P phono preamplifier? Thinking about modifying mine but, would like to understand the circuit in order to know what changes would make the most sense. There is a pretty long thread on Vinylengine but, no schematic. Any help is appreciated Thank you - ALBQ

30th March 2008, 01:05 PM	#2
ALBQ diyAudio Member Join Date: Dec 2003 Location: Albuquerque	Cambridge Audio 640P Cambridge Audio 640P - Update Well, schematic or no, I took the plunge and installed gold plated sockets and OPA2134 OpAmps in the MM section yesterday. Because of the type of solder used, getting the NE5532's out was a total pain but, the improvement in sound was more than worth it. Less congestion, greater space and better imaging yet, retains smoothness the 640P is known for. Next step is to enjoy it for while as I research an input and output cap change - get rid of the electrolytics in the signal path -ALBQ

30th March 2008, 03:36 PM	#3
sq225917 diyAudio Member Join Date: Jun 2004 Location: sheffield	http://media.bestkiteboarding.com/mm/640p.jpg op637's on the gain stage and lm4562 on the Riaa __________________ hoping to pick up some things.

30th March 2008, 10:48 PM	#4
ALBQ diyAudio Member Join Date: Dec 2003 Location: Albuquerque	Cambridge Audio 640P sq225917 I read your post on vinylengine – nice work. Any future plans or is it done? Thank you for the advice -ALBQ

14th April 2008, 03:34 PM	#5
sq225917 diyAudio Member Join Date: Jun 2004 Location: sheffield	I think it's pretty much done to be honest. I am considering splitting the power supply off the PCB and putting it in all a full width case. Maybe replace the regs with discreet units, not sure i need to probe their output noise first. __________________ hoping to pick up some things.


	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

21st January 2010, 05:40 PM	#7
marco70 diyAudio Member Join Date: Mar 2004 Location: Verona	Hi link http://media.bestkiteboarding.com/mm/640p.jpg doesn't work anymore or I'm doing something wrong ? does someone have a working link / schematic ? cheers

21st January 2010, 07:12 PM	#8
jacco vermeulen diyAudio Member Join Date: Oct 2004 Location: At the sea front, just under Rotterdam	Ca 640p __________________ Looks like Sponge Bob has killed another thread.

22nd January 2010, 02:06 PM	#9
marco70 diyAudio Member Join Date: Mar 2004 Location: Verona	Many thx, next time I'm searching deeper in other threads :-) cheers

31st January 2010, 04:27 PM	#10
sq225917 diyAudio Member Join Date: Jun 2004 Location: sheffield	Sorry guys I have to clean the worked served stuff out sometime. The vinylengine thread is the best reference, pages 28-29. i do still have the 640p in a box somewhere, if someone wanted pics. I've done nothing to ti since, and to be honest KCS's version was taken much further than mine was. __________________ hoping to pick up some things.

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

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
cambridge audio cd-6	chight	Digital Source	0	25th November 2008 05:35 AM
R50 Cambridge Audio :)	PhaseLockLoopy	Multi-Way	2	27th May 2008 10:37 PM
Cambridge Audio 640C No audio output PLEASE HELP!	Kajman	Digital Source	3	10th December 2007 09:45 AM
CA 640P opamp advice please	ben556473	Chip Amps	5	17th November 2007 03:10 PM
Cambridge audio A3 i	homertooties	Solid State	3	20th November 2005 03:52 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