Arcam Alpha mods - Page 15 - diyAudio
Go Back   Home > Forums > Source & Line > Digital Source

Digital Source Digital Players and Recorders: CD , SACD , Tape, Memory Card, etc.

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 5th July 2011, 10:25 PM   #141
diyAudio Member
 
Join Date: Jun 2008
Hi Simon

Did you read this statement below by ecdesigns in the ' building the ulitmate NOS dac using TDA 1541A ' ?
OK, we're not NOS people but it's quite an eye opener anyway :

Originally Posted by -ecdesigns-
Tuning the capacitor is the easiest way for lowering DEM clock jitter amplitude, but jitter won't be as low as with an low jitter external DEM clock (DEM clock oscillator intrinsic jitter). So this modification improves sound quality over the 470 or 680pF, but still isn't optimal - unquote

So, another simple mod without doing DEM exists by getting a better lock to BCK using one of 9 values of cap outlined in the thread.

I'll be ordering the caps tomorrow - I'll let you know what happens if your interested.

I'm also itching to try the DEM mod .....but I want you to do it first....
Hope all is well

Andrew
  Reply With Quote
Old 5th July 2011, 10:29 PM   #142
SimontY is offline SimontY  United Kingdom
diyAudio Member
 
SimontY's Avatar
 
Join Date: May 2003
Location: Sheffield, North England
Send a message via MSN to SimontY
Hi Andrew,

I recall reading about the optimal caps but thought it would be so hard to hear the difference I just left it alone... for now. I'm very interested in what you discover. I'll do the DEM re-clock at some point.

Simon
  Reply With Quote
Old 5th July 2011, 10:31 PM   #143
diyAudio Member
 
Join Date: Jun 2008
some more...

so instead of building the differential 352khz DEM clock (derived from masterclock) is it worth to try with only one 250 pF quality cap that will lock on 352.8 khz on DEM pins (16,17) ?

Answer was ' yes ' but not as good as proper DEM job - I'll bet you've read this already ?

Andrew
  Reply With Quote
Old 5th July 2011, 10:33 PM   #144
SimontY is offline SimontY  United Kingdom
diyAudio Member
 
SimontY's Avatar
 
Join Date: May 2003
Location: Sheffield, North England
Send a message via MSN to SimontY
That's cool to know. Is that a readily available value or is it made up of 220pF + 22pF + 8pF or something mad like that??
  Reply With Quote
Old 5th July 2011, 11:00 PM   #145
diyAudio Member
 
Join Date: Jun 2008
No, actually straight 250pf exists in silver mica and styrene.
Though the guy insists low tolerance of 1% ......what ?
I've found mica's at 2% and I've asked him the question already - is it oK to use.

If I have to buy a bag full I'll send you some foc !!

Cheers

Andrew
  Reply With Quote
Old 5th July 2011, 11:15 PM   #146
SimontY is offline SimontY  United Kingdom
diyAudio Member
 
SimontY's Avatar
 
Join Date: May 2003
Location: Sheffield, North England
Send a message via MSN to SimontY
Thanks Andrew! Clearly the value is ultra-critical.
  Reply With Quote
Old 7th July 2011, 01:11 AM   #147
diyAudio Member
 
Join Date: Jun 2008
OK, I've got three 2% mica's coming - apparently that's fine.
Considering my styrene's were 10 % means 2% is a bit of a result !

I need two - the other one's yours.
Only one issue - the pitch is about 12 mm !
I'll give it a go anyway.

If you PM me your address I'll send it as soon as they arrive.

Andrew
  Reply With Quote
Old 7th July 2011, 10:08 AM   #148
SimontY is offline SimontY  United Kingdom
diyAudio Member
 
SimontY's Avatar
 
Join Date: May 2003
Location: Sheffield, North England
Send a message via MSN to SimontY
Thanks Andrew, a PM has been sent your way.

12mm is very wide (typical silvered mica) but they usually come with long leads IIRC so it should be ok to fit.
  Reply With Quote
Old 9th July 2011, 11:59 PM   #149
diyAudio Member
 
Join Date: Jun 2008
They're here !

It's in the Alpha 5 now but it's too early for me to comment as I'm half way through a bottle of red - plus the 5 is completely different sounding to the Alpha
My poor Alpha 5 gets everything thrown at it first to see if it explodes and if it doesn't after a few hours I apply it to THE ' reference '

Hopefully tomorrow I can get it in and report back.
No probs though and no ' nasties '....meaning it's not worse for sure !

Yours will be with you Tuesday

Cheers
  Reply With Quote
Old 10th July 2011, 09:43 PM   #150
SimontY is offline SimontY  United Kingdom
diyAudio Member
 
SimontY's Avatar
 
Join Date: May 2003
Location: Sheffield, North England
Send a message via MSN to SimontY
That's great Andrew! Any further comments on the sonics? Is a new cap in the reference machine yet?
  Reply With Quote

Reply


Hide 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
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Arcam Alpha 5 cd schematics and mods wanted Chivvyp Digital Source 5 21st March 2010 11:36 AM
Arcam Alpha Plus amc184 Digital Source 6 17th January 2008 07:01 PM
arcam alpha 7 big jim Solid State 3 19th June 2006 12:40 PM
Arcam alpha 9 pumpkin Solid State 0 5th October 2005 07:31 PM
Arcam Alpha 8 ManUtd Digital Source 4 5th April 2004 03:23 PM


New To Site? Need Help?

All times are GMT. The time now is 08:06 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2