[spendorspain]

Quote:

Originally Posted by FritzS Jose please can you post the images again - I cannot open it.

Hi, Fritz

I'm sorry, but I can't post the pictures again because the system doesn't allow to post attachments that they are already in the thread. However, I (and others) have no problem for opening them and perhaps is a problem with your browser configuration.

Regards
Jose

 

[FritzS]

Quote:

Originally Posted by spendorspain Hi, Fritz I'm sorry, but I can't post the pictures again because the system doesn't allow to post attachments that they are already in the thread. However, I (and others) have no problem for opening them and perhaps is a problem with your browser configuration. Regards Jose

Hi Jose
I found the reason - my firewall - ZyWALL 5 - use an IDP / INTRUSION DETECTION AND PREVENTION
- I disabled this and could download the pics. But I talk about with the ZyXEL developer --> this is another story

 

[FritzS]

Quote:

Originally Posted by spendorspain Hi, head-fiers I have some comments about the AD8065 op-amp used as IC1 in WNA mkII headphone amplifier (the IC in the rail splitter is a LM6171). I’ve modify my amp with new wiring to make it very easy to change from the standard cap-coupled output to a direct output (see pictures)and I’ve extensively compared the “capless” AD8065 with the LM6171 (plus the C4 mandatory output cap). Jose

Have you test AD8065 vs AD843 vs LM6171 vs SA5534/SE5534?

With caps - you use Black Gates (1000uF/25V Nx bipolar type) are in C4 position? Bypassed?
The other electrolytic-caps are from/types?

 

[spendorspain]

Quote:

Originally Posted by FritzS Have you test AD8065 vs AD843 vs LM6171 vs SA5534/SE5534? With caps - you use Black Gates (1000uF/25V Nx bipolar type) are in C4 position? Bypassed? The other electrolytic-caps are from/types?

Hi Fritz

I've tested only AD8610, AD8065 and LM6171.
AD8610 is lifeless, lethargic and dead for my musical tastes and headphones (Grado HP-2 recabled with silver wire). Its only virtue was a good midband, with good voices, but no high-end detail or space. It seems that in other amplifiers this op-amp shines (its specs are very good), but not in my case.
Regarding AD8065 and LM6171, see my previous post.

The C4 cap is a BG bypassed with the EvoxRifa 4.7uF polyprop cap originally in C1 position (I had only these for trying the bypassing, but I'll order some others to experiment) and it does improve the sound in the highs and in the detail retrieval. The other caps are the original Rubycon ZA (not yet bypassed).

BTW, Have you, or somebody else, any idea about the loud thump at AD8065 turn-on and -off? It puzzles me. I've measured offset and it is OK (1 and 8 mV).

Regards
Jose

 

[PinkFloyd]

Quote:

Originally Posted by spendorspain BTW, Have you, or somebody else, any idea about the loud thump at AD8065 turn-on and -off? It puzzles me. I've measured offset and it is OK (1 and 8 mV).

Hi Jose,

The thump is perfectly normal and will not damage your headphones, don't worry! You'll notice the amp thumps with most opamps but is most noticeable with the 8065, I asked David about this and he said it was ok... can't remember the reason why I will ask him........ anyways don't worry about it it's just a short thump like someone whacking a drum (probably a very short dose of DC at turn on / turn off) it won't damage your headphones. You can always "hot plug" your 'phones once the amp is turned on.

 

[spendorspain]

Quote:

Originally Posted by PinkFloyd Hi Jose, The thump is perfectly normal and will not damage your headphones, don't worry! You'll notice the amp thumps with most opamps but is most noticeable with the 8065, I asked David about this and he said it was ok... can't remember the reason why I will ask him........ anyways don't worry about it it's just a short thump like someone whacking a drum (probably a very short dose of DC at turn on / turn off) it won't damage your headphones. You can always "hot plug" your 'phones once the amp is turned on.

Thank you very much, Mike. The thump is much, much louder than with AD8610 or LM6171, and real loud and frightening (perhaps my 32 ohm-impedance Grados are more susceptible or I'm not an enough brave headfier

).

Perhaps the best answer to this problem, whatever it is its cause, is the easier: to unplug the headphone before switch-off and after switch-on with no signal present (potentiometer set to max attenuation). After all, this is what a delay-relay does in many amplifiers: connect the load several seconds after turn-on and viceversa. With the dummy resistors in the socket the amp never sees no load at its output, and the brief contact that is made between "left live" and "right live" and ground (i.e.: a brief short-circuit in both channels) when pushing the plug into the socket every time I want to listen to the amp is inoffensive if there is no music playing. Am I right?

I've just measured DC offset at output socket without output capacitor and my multimeter read as follows:

channel A: 0.20 mV at turn-on and 0.98 at turn-off
channel B: 0.88 mV at turn-on and 0.488 mV at turn-off

It seems the AD8065 in channel B has a strange DC behaviour. Do you think it is defective? I've not measured DC offset with output caps, but I've heard the loud thump at turn-off even with them in place (but with output caps no DC is allowed to pass through them to headphones, isn't it?), and perhaps here lies another problem. If the cap-less amp is unexpectedly turned off (a power cut, for example), half a volt of DC goes to the headphones still plugged into it, which is bad, however brief is this condition. What do you think about it? (I know: I'm a chicken

)

Best regards
Jose

 

[FritzS]

some about caps - but in german

http://www.fragjanzuerst.de/iz/audiokondensatoren.pdf
Elektor jan. 1987

http://www.audiomap.de/forum/index.p.../mesg_id/17774
... der mir mit Abstand sympathischte Bypass C ist der NX 0,1er von Black Gate. Wenn eine Spannungsfestigkeit von 50 Volt reicht und dir der Preis nicht zu hoch ist ( www.audiotuning.de), dann ist das ein ernsthafter Kandidat
...aber der 0,1er NX ist wirklich ´ne Wucht! Für 2,60€ das Stück bringt er genau so viel, wie 8€ teure Supreme oder Auri-Cap.

 

[FritzS]

Quote:

Originally Posted by spendorspain Thank you very much, Mike. The thump is much, much louder than with AD8610 or LM6171, and real loud and frightening (perhaps my 32 ohm-impedance Grados are more susceptible or I'm not an enough brave headfier ). Best regards Jose

The way out - build a turn-on delay muting and DC offset protection circuit like
http://www5.head-fi.org/forums/showthread.php?t=119066
http://headwize.com/ubb/showpage.php?fnum=3&tid=5866
http://www.amb.org/audio/epsilon12/

or from Dr. White
http://www6.head-fi.org/forums/showp...&postcount=433

 

[PinkFloyd]

Answer from David re: "thump" as follows:

"You get this with direct coupled versions of the headamp because there is a very brief instant of dc offset before the amp settles to its normal operating condition. The only way to fix it is to arrange for either the power to ramp up slowly or the amp to turn on gradually. Other than to use a headphone protection unit, there isn't an easy way to accomplish this with the system as it stands. Fortunately the thumps don't do any harm to your headphones."

Well, there you have it Jose. Far from ideal as far as you're concerned and maybe the headphone protection unit should be incorporated into the kit or a MKlll designed with power which ramps up slowly. As David says, this will not damage your headphones but I can appreciate your concern especially if you're using mega buck headphones.... the last thing you want to hear is a loud "crack" every time you turn the amp on or off.

The cheapest / easiest solution is to keep your amp permanently powered up or to hot plug the headphones once the amp is powered up and to remove them before switching it off....... you've got the dummy load resistors on the head socket and (unless you're really ham fisted) you won't short the amp by plugging / unplugging the 'phones with it switched on...... I never switch an amp on with the headphones plugged in and I always turn down the volume and remove the headphones before switching it off...... it's always worked fine for me (touchwood!)

If you think the WNA is weird you want to try the X-Can V3! switch it on and there's nothing at all for about 10 seconds..... switch it off with the 'phones plugged in and you get a funny "whoosh" sound...... well cool! Not as dramatic as a loud "crack" but fun nonetheless

All this is making me want to reach for the soldering iron and make another kit

All the best.

Mike.

 

[nph134]

Well I've just spent all morning reading this thread...couldn't stop once I'd started hehe!

I'm very impressed with the interesting and informed posts especially by you pinkfloyd. It's also nice to see someone who is obviously quite a technical person not being blinkered to the more subjective aspects of music.

I've just ordered some HD650s and am getting a WNA headphone amp for my xmas prezzie (perk of having David as a father). Hammond case, stepped attenuator...the works. After I have them and have "tested" them I'll hopefully have something of a little more substance to add here.

 

[PinkFloyd]

Quote:

Originally Posted by nph134 Well I've just spent all morning reading this thread...couldn't stop once I'd started hehe!

Welcome to Head-Fi nph134

All morning reading this??? man it must be dull where you live

Quote:

Originally Posted by nph134 I've just ordered some HD650s and am getting a WNA headphone amp for my xmas prezzie (perk of having David as a father). Hammond case, stepped attenuator...the works. After I have them and have "tested" them I'll hopefully have something of a little more substance to add here.

Nice one! try and persuade him to shove a cascode PSU into your stocking too

I'll probably treat myself to another WNA for Christmas... boxing day is no fun unless you're soldering!

Have fun with the amp and 'phones and let us know how you're getting on with them.

All the best.

Mike.

 

[FritzS]

Have anyone tested Panasonic FC instead of Rubycon or Nichicon electrolytic capacitors?

 

[PinkFloyd]

Quote:

Originally Posted by FritzS Have anyone tested Panasonic FC instead of Rubycon or Nichicon electrolytic capacitors?

Yeh man, Panasonic FC is probably my favourite capacitor and I have used it extensively in amps like the X-Can with very good results indeed! I would certainly try it in the WNA the only reason I didn't try it was the LM6171 wasn't too keen on low ESR caps in the MKl so I ruled the FC's out.

They should be fine in the MKll and their signature is very liquid, flowing and smooth.... lovely caps

 

[PinkFloyd]

I just noticed that all of the pictures I had posted in this thread were not showing, I've fixed the problem and they should all now be visible throughout the thread

 

[GoRedwings19]

Hi Mike (pinkfloyd) how would you describe the sound of the WNA 2 compared to the version 1.?