New WNA MKlll announced!
Mar 25, 2006 at 7:04 PM Post #17 of 33

rickcr42

Are YOU talkin' to me?
Joined
Jun 21, 2001
Posts
13,874
Likes
14
I will be following this thread with interest unless it gets to one of those thirty page mini-series deals which is way past ricks attention span and will have to bail

very_evil_smiley.gif
 
Mar 26, 2006 at 1:55 PM Post #18 of 33

FritzS

500+ Head-Fier
Joined
Jan 2, 2002
Posts
777
Likes
167
Quote:

Originally Posted by PinkFloyd
I haven't ordered the parts yet but found some of them kicking about so have fitted a few resistors, the 100K trimpots and the BD140 transistors. Will come back to this thread once I have fitted the rest. So far, so good
smily_headphones1.gif



What type's / manufactors of resistors use you?

My first look - the schema of the splitter is the same of MK II?!

You order from "RS" too
smily_headphones1.gif


I wait for your first hearing (compairing) test
580smile.gif
 
Mar 27, 2006 at 2:26 PM Post #23 of 33

FritzS

500+ Head-Fier
Joined
Jan 2, 2002
Posts
777
Likes
167
Quote:

Originally Posted by PinkFloyd
Here are the differences Fritz:
MKll rail splitter: vs .MKlll rail splitters:



I have study the PCB - the difference is position of the capacity-booster transitors - MKII at input - MKIII at output.

Quote:

Originally Posted by PinkFloyd
Note: MKlll uses constant current diodes throughout the amp, no standard diodes at all just 3.5mA & 5.6mA CRD's across the board (and splitters)


Which values of CRD's are used in rail splitter - 3.5mA or 5.6mA?
which values of CRD's are used in diamond buffer - 3.5mA or 5.6mA?
On my understanding, the trick to use different values of CRD's to flow the difference into the output of the OP (for Class-A) did not work with diamond buffer! For this feature we must use an additional CRD.

What the values of the feedback network resistors?
- input of OP to ground (1k in MKII) / - input to output of OP (330k in MKII - local feedback) / - input to output of diamond buffer (3k3 in MKII - overall feedback)?

What the values of the ZOBEL net? And the resistor in series to the output?
I calculate a 100 nF about 20 kHz - it haves ~ 80 Ohm / 100 kHz ~ 16 Ohm.
Which type of caps I should use for my Senn - polyester (MKS) or polypropylene (MKP)?
I remember Mike has written about this here ..... but where?

Today I use in MKII no input cap (4,7 uF), no Zobel, no local feedback (330k) and a Holco H2 15 Ohm plus 1000uF BG in series to my Sennheiser HD600 headphone - the sound is very clear, very rich in details, analytic ....
I did not test - what's the difference in sound by use the local 330k feedback and/or the ZOBEL net?
 
Mar 27, 2006 at 2:44 PM Post #24 of 33

FritzS

500+ Head-Fier
Joined
Jan 2, 2002
Posts
777
Likes
167
I have some samples of National LM2940LD / LM2990T (12V, 15V) and some samples of Linear Technology LT1086IT / LT1185IT / LT1085IT (12V, variable) in my stock.

I want to make my own PSU - what your experience about National or Linear Technology regulators?
 
Mar 28, 2006 at 6:49 AM Post #25 of 33

FritzS

500+ Head-Fier
Joined
Jan 2, 2002
Posts
777
Likes
167
Quote:

Originally Posted by PinkFloyd
Just standard 1% types Fritz, David recommends welwyn RC55Y but I ain't paying a quid for "1" resistor, no way
tongue.gif

Mike.



welwyn RC55Y
RS - 5 pices per value EUR 5,01 plus tax

Have you seen for Holco H4 0.5Watt Precision Resistors or Holco H8 0.25Watt Precision Resistors?

I found http://www.viewcom.force9.co.uk/data/holcores.htm
Holco H8 0.5% 0.25Watt Precision Resistors
Price: | 1+ 0.20 each | Pack of 10 = 1.60 | GB Pounds

or http://www.thlaudio.com/HolcoRmn.htm
http://www.percyaudio.com/
 
Mar 31, 2006 at 2:05 PM Post #28 of 33

FritzS

500+ Head-Fier
Joined
Jan 2, 2002
Posts
777
Likes
167
Quote:

Originally Posted by PinkFloyd
Here is the populated MKlll. I can't say anymore about it for reasons that may become clear later on but, here it is:[/IMG]


Great performance!
580smile.gif


I see you use Panasonic FC or FM electrolytics, WIMA MKS3 polyester (why not MKP polypropylene?), EPCOS 4,7 uF (I think here polypropylene)

In the background I see you have a stock of OP's
smily_headphones1.gif
 
Apr 1, 2006 at 1:58 PM Post #29 of 33

raja

100+ Head-Fier
Joined
May 22, 2003
Posts
108
Likes
12
Quote:

Originally Posted by biovizier
Sorry but I have sold the preamp and replaced it with a transformer volume control. I only have the mk 2 headamp now.



So you decided to try it out eh???
What do you reckon


Congratulations Mike, I assume you are the new owner of White Noise Audio???
 

Users who are viewing this thread

Top