Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Solid State Talk all about solid state amplification.

Modding Azur 640A
Modding Azur 640A
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
Reply
 
Thread Tools Search this Thread
Old 13th May 2016, 03:56 AM   #131
Ian Finch is offline Ian Finch  Australia
diyAudio Member
 
Join Date: Apr 2010
Location: Coffs Harbour, NSW
The power amplifier designs and supplies are essentially the same in 540/2 and 640/1 so rating it 60W instead of 65 is likely a paperwork figure, perhaps permitting a smaller transformer to be used and give people a reason to pay more for the 640A V2, which you could say is no different to 540A V2 in practical listening terms and features. It's not all strict scientific fact in marketing so I wouldn't stake my life or even a recap job on what can be squeezed out of SAP15s with 45V rails. The SAP15s are now obsolete but STD01 carry on where they left off.
http://www.semicon.sanken-ele.co.jp/...d01n_ds_en.pdf

In theory, 45V rails should permit 100W/8R with an EF output stage but I suspect the AC from the small transformer secondary windings is quite rubbery and dips under load. This is common in UK audio design and works well to protect the output devices in the event of overload but at the cost of dynamic range. The modest difference between power into 8R and 4R loads all but spells out this design approach.

Don't be concerned about an increased DC rail voltage with 50% more capacitance, as it won't be that much and will quickly vanish under output load, where voltage will count. The question centres around the benefit, if any, of increasing capacitance above even as little as 4,700uF. Unless the amplifier is higher power and thrashed at its peak power levels, the extra can't help linearity unless it just compensates for badly deteriorated caps - unlikely at present.

Missed your post but if you have Nichicon KW, not the best but fine because of size mainly.
__________________
If only I had listened....

Last edited by Ian Finch; 13th May 2016 at 04:11 AM.
  Reply With Quote
Old 13th May 2016, 04:36 AM   #132
Poita is offline Poita  Australia
diyAudio Member
 
Join Date: Mar 2010
Location: Adelaide, SA
I haven't bought any of the caps yet, just working my way through the boards to find what I can replace them with. I wanted Elna Silmic II but they don't come in the 63V required Might be able to use them on the smaller voltage caps. Hence looking at the KW for the 63V ones unless you have a better suggestion??

Using Nichicon PW for the 8 PSU caps. Nichicon ES for the bi-polar.

Edit: Found the Nichicon FG and KZ series. They appear to be better so checking them out.
__________________
Cambridge Audio 640A V2, 640C V2
Ascension Floorstanders - Customised Summoner 1073TL , 3 way Transmission line

Last edited by Poita; 13th May 2016 at 04:44 AM.
  Reply With Quote
Old 15th May 2016, 01:26 AM   #133
dzebrys is offline dzebrys  Poland
diyAudio Member
 
Join Date: Mar 2009
Quote:
Originally Posted by Poita View Post
OK more queries!! This time on capacitor type. For the power supply/amplifier PCB, I can't use Elna Silmic II anymore as they don't have the values in 63V only 50V.

So looking at the Nichicon range. I can find them in FW and KW (bi-polar I have all Nichicon Muse ES). Anyone have any preference or other recommendations?

Cheers
Pete
if you check scheme carefully you will notice there is already 2x2200uf per each rail per channel as caps are in parallel. you will not find same voltage rating cap with more capacitance as it broke some base physics then. what you can do is to use some free space near to power supply coil and add new caps there. this is how I've done my mod by adding 3300uf to existing one. you need 3 wires and relevant bridging within new 4 caps section (per channel).

unfortunately tapatalk is broken again and i can't add pictures here.

tapnięte talkiem
  Reply With Quote
Old 17th May 2016, 12:33 AM   #134
Poita is offline Poita  Australia
diyAudio Member
 
Join Date: Mar 2010
Location: Adelaide, SA
Here is the list so far! Managed to find pretty close substitutes for nearly all of the factory caps.
Hopefully this is of some help if anyone else goes down this path!
Click the image to open in full size.
__________________
Cambridge Audio 640A V2, 640C V2
Ascension Floorstanders - Customised Summoner 1073TL , 3 way Transmission line
  Reply With Quote
Old 17th May 2016, 10:18 PM   #135
dzebrys is offline dzebrys  Poland
diyAudio Member
 
Join Date: Mar 2009
the differece between 540 and 640 is mainly in transformer, the letter one has additional secondary for power stage, both rated 2*32.5V/2A wherein 540 has single secondary rated 2*30V/3A.

i've not finished my mod as awaiting for replacement of rubbish xunda's all around but quick check confirms it sounds with 20kuF at least the same as before mod

for me more important is to replace relays which cause channels to off and to add dac for optical input handling from media streamer. and ofc it's a lot fun
  Reply With Quote
Old 18th May 2016, 02:50 AM   #136
Poita is offline Poita  Australia
diyAudio Member
 
Join Date: Mar 2010
Location: Adelaide, SA
I noticed that the decoupling caps throughout the whole board are cheap 47nF 63V polyester MKT.
Now I can upgrade these to some WIMA polypropylene MKP which seems to be a common thing to do, but what is the consensus on on using tantalum caps? They typically have very good high frequency rejection which I would have though to be an advantage in a decoupling capacitor? Would replace them with 100nF 35V tant.
I have seen some threads mentioning that tants are not recommended in the signal path, but these aren't, they are just used for rail decoupling on the opamps.
__________________
Cambridge Audio 640A V2, 640C V2
Ascension Floorstanders - Customised Summoner 1073TL , 3 way Transmission line
  Reply With Quote
Old 18th May 2016, 04:38 AM   #137
Ian Finch is offline Ian Finch  Australia
diyAudio Member
 
Join Date: Apr 2010
Location: Coffs Harbour, NSW
What's wrong with the original MKT film caps or Multilayer ceramics - the preferred types for decoupling? Size is important with unshielded components and polypropylene film types lose by size, lead length and noise proneness what may be gained in microscopically lower distortion. Tantalums may work fine, just like wet electrolytics, if suitable voltage ranges are available and there is no possibility of exceeding it. They are polarized, not long-life components and only have a size advantage to offer audio.

Don't swap everything in sight based on a few specifications since there are more factors in component choices than the obvious ones that beginners make such a blinkered, ritualistic fuss of. I suspect there is little to improve in such a recent model and most that is done will be retrograde as far as performance is concerned. How it sounds has little to do with fidelity though - that's more the "flavour" of distortion.
__________________
If only I had listened....
  Reply With Quote
Old 18th May 2016, 05:28 AM   #138
Poita is offline Poita  Australia
diyAudio Member
 
Join Date: Mar 2010
Location: Adelaide, SA
Cheers thanks for that Ian. There seems to be a lot of hype about pretty much any component in audio devices and given I am fairly new at audio electronics it's confusing trying to sort out the snake oil from the things which give tangible benefits.
__________________
Cambridge Audio 640A V2, 640C V2
Ascension Floorstanders - Customised Summoner 1073TL , 3 way Transmission line
  Reply With Quote
Old 19th May 2016, 05:22 PM   #139
dzebrys is offline dzebrys  Poland
diyAudio Member
 
Join Date: Mar 2009
speaking of mods, does anybody knows what in this amp consumes 10w at standby? and any way to cut this off?

tapnięte talkiem
  Reply With Quote
Old 20th May 2016, 12:57 AM   #140
restorer-john is offline restorer-john  Australia
diyAudio Member
 
Join Date: Jan 2004
Location: gold coast
Standby transformer of dubious quality?

Do they keep the amp's front end powered up to keep it 'warm'?

Switch it off with a proper inline switch or switched power board. 10w in standby is either a fault or very poor design.
  Reply With Quote

Reply


Modding Azur 640AHide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Cambridge Audio Azur 640C V1 dome406 Digital Source 12 15th December 2012 08:18 AM
Modding a Cambridge AZUR 740C Cormac Digital Source 14 2nd March 2012 04:20 PM
Blown-up Azur 340A borges Chip Amps 7 17th March 2010 03:17 PM
Cambridge Audio 640A V2 - service manual Paolo.n Solid State 0 7th July 2009 11:19 AM
Cambridge Audio Azur 640A toroidal power transformer (115V) limono Swap Meet 1 25th December 2008 04:57 PM


New To Site? Need Help?

All times are GMT. The time now is 06:06 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio
Wiki