[PinkFloyd]

Quote:

Originally Posted by FritzS The both input caps (4,7uF) I will replace with a 1 kOHM Holco resistor (possibly with a Murata Ferrite bead in serial). I will start with no 330 k so I can change easy between LM6171 and AD843.

Just make sure if you remove the input caps that the DC offset remains at 0mV at "all" volume levels when running the LM6171... obviously you will have output caps in position?

 

[FritzS]

Quote:

Originally Posted by PinkFloyd Just make sure if you remove the input caps that the DC offset remains at 0mV at "all" volume levels when running the LM6171... obviously you will have output caps in position?

My Philips CD 650 have caps in in the output - I want to change them to Nichicon KZ soon.

 

[FritzS]

Quote:

Originally Posted by PinkFloyd It's easier to snip the tags as shown in the picture. This ensures a "perfect" fit with the head socket being flush with the PCB and saves farting about soldering six silver wires into position, hell what's the point of making provision for a potentiometer and head socket on the board and then supplying a head socket that doesn't fit.... sure you can solder wires onto the tags or cut the tags down but I'd prefer a head socket that was a perfect flush fit on the PCB... either that or make the darned holes on the PCB large enough to accommodate the gold plated head socket...... sorry but little things like this really annoy me, the whole idea of making provision for board mounted components is that the component will fit straight onto the board without having to customise it to fit. Rant over.

I have done as you wrote but one of the tag I must cut off - it's not in line as the others - I put the silver wire extra, the hole are lare enough, and solder it above the PCB too
My WNA works now - the first burn in test with my Senn HD 600 headphones - "WOW" its much more better than the headphone output of my Philips CD 650 or of the Yamaha CR 2040 receiver - both are "old HiFi classics". A complete test of hearing follows - with Eva Cassidy "Live At Blues Alley" and some other music all my hairs stand up, I have never heared this so before

First pics are here http://www.stockhammer.at/hifi/wna.php but my wna is not completely done

 

[spendorspain]

Hi all Head-Fiers and happy new year.

It's nice to see this forum re-energized by FritzS and Mike... Perhaps these quiet weeks we all have been listening to our WNA, simply enjoying our favorite music, but always it's possible to upgrade... or not: I've listening to the Linkwitz modified crossfeed and I dont't like it. It was very effective in giving more depth to the music but at the expense of reduced width and a general thickening of the sound, even in the low crossfeed setting. In some music with extreme L-R effects or an exaggerated treble perhaps the advantages outweigth these problems, but in classical music the vast majority of recordings have natural acoustic ambience enough. Or perhaps I'm used to listening to the headphone "cinemascope" perspective (however, I'll try the Meier natural crossfeed soon).

I would recommend to FritzS to bypass the output capacitors C4. I'm currently using a 4.7 uF Evox and a 0.1 uF Wima FKP3 polypropylene film caps (the ones I had at hand), and the sound have improved over the BG Nx 1000uF alone. I'm going to order better bypass caps (a 5 or 10uF AmpOhm and a 0.1uF Mundorf Supreme or Silver in oil, installed in a new bigger case), but the cheap and easy bypassing I have now is well worth it.

I have a question about class-A operation in WNA headphone amp. According to several posts in this forum, I have to use a 100 ohm resistor in R6 position and a 160 ohm resistor in R5 (instead of the standard 75 and 121 ohm resistors) and add a little heatsink in each Tr1-4 transistors. However, I can't find an exact 160 ohm resistor, but only 158 or 162 ohm resistors. Which value is preferred, 162 or 158 ohm? Perhaps this is a critical value and the R5 and R6 values must have an exact relationship between them (I don't know). In any case, I don't like to order the wrong one and some help would be very appreciated.

Best regards,
Jose

 

[PinkFloyd]

Quote:

Originally Posted by spendorspain Hi all Head-Fiers and happy new year.

Happy New Year to you too

Quote:

Originally Posted by spendorspain I have a question about class-A operation in WNA headphone amp. According to several posts in this forum, I have to use a 100 ohm resistor in R6 position and a 160 ohm resistor in R5 (instead of the standard 75 and 121 ohm resistors) and add a little heatsink in each Tr1-4 transistors. However, I can't find an exact 160 ohm resistor, but only 158 or 162 ohm resistors. Which value is preferred, 162 or 158 ohm? Perhaps this is a critical value and the R5 and R6 values must have an exact relationship between them (I don't know). In any case, I don't like to order the wrong one and some help would be very appreciated.

Fitting a 100R and 160R will only increase the quiescent current by about 20%. The opamp is already biased into class A and fitting 160R / 100R into R5 and R6 will only increase the quiescent current. If you do want to increase the quiescent current by 20% then you must fit adequate heatsinks to the transistors to dissipate the heat.... the values are not critical so you can have 160R / 100R +/- 10% As long as the values are the same per channel you don't have to strictly adhere to 160 / 100 you could go 145 / 90 140 / 85 etc. etc. to tailor the percentage of quiescent current increase. 160 / 100 gives a 20% (or thereabouts) increase in QC and I certainly wouldn't go much higher than 160 / 100... if you want 10% increase in QC then something like 140 / 90 should be about right (David will know the exact figures)

 

[PinkFloyd]

Quote:

Originally Posted by FritzS My WNA works now

Nice one Fritz! It's a great feeling when they fire up first time isn't it? How did you find the build and the construction manual in general?

Quote:

Originally Posted by FritzS the first burn in test with my Senn HD 600 headphones - "WOW" its much more better than the headphone output of my Philips CD 650 or of the Yamaha CR 2040 receiver - both are "old HiFi classics". A complete test of hearing follows - with Eva Cassidy "Live At Blues Alley" and some other music all my hairs stand up, I have never heared this so before

Give it a couple of weeks for the caps etc. to form.... it gets better

Quote:

Originally Posted by FritzS First pics are here

Looking great Fritz, nice website you've got there too.

Mike.

 

[FritzS]

Happy new year to all Head-Fiers

Quote:

Originally Posted by spendorspain Hi all Head-Fiers and happy new year. I would recommend to FritzS to bypass the output capacitors C4. I'm currently using a 4.7 uF Evox and a 0.1 uF Wima FKP3 polypropylene film caps (the ones I had at hand), and the sound have improved over the BG Nx 1000uF alone. I'm going to order better bypass caps (a 5 or 10uF AmpOhm and a 0.1uF Mundorf Supreme or Silver in oil, installed in a new bigger case), but the cheap and easy bypassing I have now is well worth it.

This thought I have too, I have the both 4.7 uF Evox left over - I installed 1 kOHM instead of to eliminate the noise if you turn the potentiometer in CCW position, as reported in this thread - I use LM 6171 - for bypassing caps the ratio should be 1:10 ... 1:100
please see here (all in german):
http://www.fl-electronic.de/modifika...ndensator.html
http://www.fl-electronic.de/modifika...ndensator2.jpg
and http://www.audiomap.de/forum/ "Folien Bypass zu Elkos" Thema #17774

Quote:

I have a question about class-A operation in WNA headphone amp. According to several posts in this forum, I have to use a 100 ohm resistor in R6 position and a 160 ohm resistor in R5 (instead of the standard 75 and 121 ohm resistors) and add a little heatsink in each Tr1-4 transistors. However, I can't find an exact 160 ohm resistor, but only 158 or 162 ohm resistors. Which value is preferred, 162 or 158 ohm? Perhaps this is a critical value and the R5 and R6 values must have an exact relationship between them (I don't know). In any case, I don't like to order the wrong one and some help would be very appreciated. Best regards, Jose

The use of little heatsink on each Tr1-4 are recommanded, they are hot in original kit - but which heatsink is small enough? I search for a clip-on (TO-126 / SOT32) typ - please tell me the manufacturer & typ.
The 10 Ohm resistors are warm - the current on each are ~ 42 mA.
The power on each Tr1-4 transistor I~42mA U~10V P~420mW

 

[FritzS]

Quote:

Originally Posted by PinkFloyd Nice one Fritz! It's a great feeling when they fire up first time isn't it? How did you find the build and the construction manual in general?

The manual should be a bit more detailed!
For WNA MKIII - the place for caps should be larger, so I use RIFA PHE 450 0,1 uF / 250V the are "fatter" than the PHE 428 - here gives 5mm and 10mm RM types too!
David use a thin twisted 3 pol. wire for power connect between rail splitter and each amp - I use the twisted (red/black) wire for +V -V and the green wire for ground (on bottom side of PCB) - and use the twisted (red/black) wire for output (P2 to Jack) on forefront of PCB.

This parts I use:
C5, C6 Nichicon FG 100 uF, 25V
C11, C12 Nichicon KZ 220 uF, 25V
C7 Nichicon KZ 220 uF, 50V
C4 BlackGate NX 1000 uF 25V
C2, C3, C8, C9, C10 Evox Rifa PHE 450 0,1 uF / 250V (follower of PHE 428)
R11 instead of lamp - 15 OHM Holco H2
instead of C1 - 1,02 kOHM Holco H4
IC1, IC2 LM6171
J2 ferrite

Currently there is no ZOBEL net, no bypassing the electrolytics with small caps, no additional 330 kOHM feedback

New pics are here: http://www.stockhammer.at/hifi/wna.php

 

[FritzS]

Quote:

Originally Posted by spendorspain Hi all Head-Fiers and happy new year. I would recommend to FritzS to bypass the output capacitors C4. I'm currently using a 4.7 uF Evox and a 0.1 uF Wima FKP3 polypropylene film caps (the ones I had at hand), and the sound have improved over the BG Nx 1000uF alone. I'm going to order better bypass caps (a 5 or 10uF AmpOhm and a 0.1uF Mundorf Supreme or Silver in oil, installed in a new bigger case), but the cheap and easy bypassing I have now is well worth it. Best regards, Jose

Hi Jose - let know us the results!
If the caps not go well together some resonances can occur - so the parasitic L (inductance) from the 1000 uF have a resonance with the bypass cap, if you use more different bypass caps, so on ... - please show:
http://www6.head-fi.org/forums/showp...&postcount=697
The best way - to measure them!

 

[12796]

All my emails to Dr White are getting bounced. Anyone else having this problem?

 

[spacejay]

Hello all

New entrant here.

I have just finished building the WNA mk II head amp with no previous experience at all in this sort of thing, so if anyone reading this is thinking of buying one, do it cause if I can do it you can do it.

I did find soldering some of the smaller wires very fiddly and in fact, following my impatience to get the thing up and running wired a positive to a negative and blew some capacitors and op amps. Oops. Still, I learnt a lot.

I have a stupid question as befits a total novice. I replaced the blown Rubycon with a 7 pence Jamicon from Maplin. David said I'd be advised to replace it with the Rubys but any advice on the best caps and what exactly do they do?

Also any tweaks. I've only had it running a couple of hours so I gather the sound won't be "fully formed " for a while (I think I read somewhere 400 hours which seems a long time ).

My only "criticism" is the LED which is the luminous equivalent of an H bomb going off.

 

[StevieDvd]

Welocome to the forums and Team WNA.

Well done on your build - it's a better learning scenario when you fix things that can and do go wrong.

I'm sure either Pinkfloyd or one of the more experienced WNA builders will jump in with loads of practical advice as they monitor WNA threads like hawks

Steve

 

[FritzS]

Quote:

Originally Posted by spacejay I have a stupid question as befits a total novice. I replaced the blown Rubycon with a 7 pence Jamicon from Maplin. David said I'd be advised to replace it with the Rubys but any advice on the best caps and what exactly do they do?

I use Nichicon from http://www.percyaudio.com/ - fore more please see here about http://www.stockhammer.at/hifi/wna.php
Other good caps - Panasonic FM or FC

Before power up - check up and check up and ......, then measuring and then carefully power up - I use a resistor 100 OHM, then 10 OHM in serial to the power line (from PSU to Anp) - and measuring - than power up and "fire" the headphone with music

- I use an old headphone before I use my Senn HD 600.

 

[PinkFloyd]

Quote:

Originally Posted by biovizier All my emails to Dr White are getting bounced. Anyone else having this problem?

On and off, yes.

 

[FritzS]

Hi,
has anyone tested - instead of the non-polar electrolytic caps- two polar 2000uF 25V electrolytics "face to face" (connecting with - pole) and put a resistor 81k to 10 kOHM) from this connection-point to V-
So on each cap are ~ 10 V DC