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New! WNA MKll Head-amp kit. - Page 8

post #106 of 760
2/19/05 at 5:54pm
Thread Starter 
Coming along nicely Alick

Agreed the hook up from the rail splitter to P3 is a bit of a fiddly pisser but I can understand why it's been implemented that way but can't understand why David didn't make it easy and make that part of the board "jumperable" with zero ohm resistors. The hook up wire is a wee bit tight for comfort (space between pads) and time consuming.... I see you hooked up 0V on the underside of the board... good idea, leaves plenty of space between +V & -V on the top of the board.... I used very thin PTFE wire and hooked up all three (0V +V -V) on the top of the board.... one things for sure, you don't want to use thick wire from the rail splitter to P3, one loose strand out of place and POW goes your PSU...... I agree with you Alick...... I found this part of the build very fiddly and, quite frankly, frustrating considering the board could have been designed to use jumpers, This is one part of the design David will hopefully address. Even with pin headers it would be a bloody fiddly job ..... Jumpers are the way to go......

I notice you're using the BC caps? They're pretty good and reasonably priced did you get them from Rapid? From the size of the two yellow Nitai non polars I would guesstimate that they are 16V 1000uF? I can see the RC55Y's (300R and 1K) are in place for the LM6181 what resistors did you use for the rest of the board? They look like Trueohm 0.1% 15ppm from the pic

Looking good Alick I can't wait to hear what you think of the LM6181...... I've still got them in place and am VERY happy with the sound quality indeed...... Try the MKll with the LM6171 also, there's not much in it and it'll be interesting to learn your opinion.

Look forward to it.

All the best.

Mike.

EDIT:

Thanks for the pic it will show the difference between the PCB1 and PCB2...... they are both identical with the exception that PCB2 has provision to board mount the volco and head-socket....... other than that they are identical. It's good that two boards are available to cater for all applications:


PCB1
PCB1 is similar to the previous WNA (and can also be used as a buffer amplifier) except the pcb is a little larger; there are now "two" pairs of output devices per channel to deliver a lot more grunt into low impedance 'phones; the rail splitter is now preceded by a capacitance multiplier to make performance less dependent on the quality of the external power supply so you can now get fantastic performance using a bog standard PSU; the output caps now mount on the pcb; and each channel is now completely independent ( i.e. the amp is dual mono ) so that you can have one power supply per channel. The PCB1 is ideal for people who want to use a stepped attenuator or want to build a fully balanced system using 2 boards... It can also be used as a Dual Class A Buffer Amplifer.


PCB2
PCB2 is the same as PCB1 except that the potentiometer and headphone jack mount on the pcb.
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post #107 of 760
2/19/05 at 7:45pm
Quote:
one things for sure, you don't want to use thick wire from the rail splitter to P3, one loose strand out of place and POW goes your PSU
I used solid core, just in case.
Quote:
I notice you're using the BC caps? They're pretty good and reasonably priced did you get them from Rapid? From the size of the two yellow Nitai non polars I would guesstimate that they are 16V 1000uF? I can see the RC55Y's (300R and 1K) are in place for the LM6181 what resistors did you use for the rest of the board? They look like Trueohm 0.1% 15ppm from the pic
I got all the resistors and cap's from Rapid except for the Nitais (yes, I went for the 1000uF) and the RC55Ys. All of the resistors are 0.1% except for R6, R12 and R13 for which Rapid had no stock so I just used 1%.
Quote:
Looking good Alick I can't wait to hear what you think of the LM6181...... I've still got them in place and am VERY happy with the sound quality indeed...... Try the MKll with the LM6171 also, there's not much in it and it'll be interesting to learn your opinion.
I've got both and intend to compare. It should be easy as David reckons that the optimised R2 and R3 for the LM6181 suits the LM6171 just as well. Nearly there and itching to listen.
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post #108 of 760
2/19/05 at 8:09pm

Stepped attenuator

Dr White makes a very nice balanced stepped attenuator - highly recommended. From my own experiences I would say this would be a very worthwhile but expensive upgrade compared with standard pots - prob add £100 or so to the cost but would make a big improvement. I have requested one in my version of the headamp (when I get around to ordering it ;-) ). I am running his preamp in balanced mode - he also makes single ended to balanced converters that can be used to convert the buffer unit to balanced at a lower cost. I would be interested if anyone compares a standard PSU with the cascode PSU with the capacitive multiplier arrangement.
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post #109 of 760
2/20/05 at 10:26am
Thread Starter 
Quote:
Originally Posted by Alick
I used solid core, just in case.
Yet another great idea Alick


Quote:
Originally Posted by Alick
I've got both and intend to compare. It should be easy as David reckons that the optimised R2 and R3 for the LM6181 suits the LM6171 just as well. Nearly there and itching to listen.
What values did you end up using for R2 & R3?
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post #110 of 760
2/20/05 at 10:44am
Thread Starter 
Quote:
Originally Posted by biovizier
Dr White makes a very nice balanced stepped attenuator - highly recommended. From my own experiences I would say this would be a very worthwhile but expensive upgrade compared with standard pots - prob add £100 or so to the cost but would make a big improvement. I have requested one in my version of the headamp (when I get around to ordering it ;-) ). I am running his preamp in balanced mode - he also makes single ended to balanced converters that can be used to convert the buffer unit to balanced at a lower cost. I would be interested if anyone compares a standard PSU with the cascode PSU with the capacitive multiplier arrangement.
Hi Nick,

I originally wanted to use the stepped attenuator but it was too bloomin large to fit into the enclosure I had I may well buy one and house it in its own enclosure (offboard) how many steps will you be using? I'll probably go with 24 for starters.

I haven't tried the Cascode PSU and would really love to give one a road test before actually buying one.. the one I use at the moment is the Calex open frame built into a translucent blue enclosure, sounds good to me and cost around £40 to build, it would be interesting to compare it with the Cascode PSU.... here are a few close up pics of the innards:









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post #111 of 760
2/20/05 at 10:48am

attentuator

I am using 24 steps - that is more than enough. I am already using cascode PSUs and I am about to fit CM's to all my units. I am curious about how much the CM removes dependency on the psu as I may be about to upgrade the cascode . Dr White would lend you a cascode if you wanted to try one.
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post #112 of 760
2/20/05 at 11:26am
Thread Starter 
Quote:
Originally Posted by biovizier
I am using 24 steps - that is more than enough. I am already using cascode PSUs and I am about to fit CM's to all my units. I am curious about how much the CM removes dependency on the psu as I may be about to upgrade the cascode . Dr White would lend you a cascode if you wanted to try one.
I'll try one out in the summer Nick, maybe by that time my enthusiasm will have returned.. as it is, at the present time, I'm happy with the WNA and am enjoying the music and don't see any immediate areas of the sound that "need" improving. One could go on forever trying to get every last ounce out of a piece of equipment but there comes a stage where the law of diminishing returns comes into play.

Mike.
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post #113 of 760
2/20/05 at 11:35am

attenuator

Indeed - sometimes you just have to sit back and enjoy the fruits of your labours... lest the means become the end.

Sometimes the law of diminishing returns can be broken by exceptional products, but they are very rare. Certainly all of the changes that have been made to the audiophile phono unit have changed it beyond belief and there is still some way to go - some of the future mods will also find their way into the headphone amp I am sure at some point. I think the LODR sets in quickly with tweaking... evolution of the sound as it were. To get a revolution it requires something more substantial I guess.

As you say the most immediate concern with any system is to remove any obvious flaws that impair listening. After that everything else is a a luxury but not a neccesity.
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post #114 of 760
2/20/05 at 2:55pm
Quote:
What values did you end up using for R2 & R3?
1k0 and 249R.
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post #115 of 760
2/26/05 at 4:38pm
Finished! I grabbed the opportunity of being the only one in the house today to finish my Mk 2. All I had left to do was the hook-up wiring. The co-ax cable supplied by WNA (which I believe is standard with the kit?) is a joy to work with and makes for a really neat job (well, as neat as I'm capable of). Joy of joys, it worked first time and, although I haven't listened too much yet, first impressions are of a 'fuller' sound than the Mk 1. I fitted the LM6181s to start with but will do a comparison with the LM 6171s soon. The amp is burning in as we speak and should have 5 or 6 hours on the clock before my first serious listening session with it later tonight. Here are some pictures if anyone's interested. (I'll put the lid on after I've finished this post).




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post #116 of 760
2/26/05 at 4:54pm
wow... another one... hope you'll enjoy it, alick! what's that impressive 4-pole switch on the backside for? second input?
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post #117 of 760
2/26/05 at 4:59pm
Quote:
what's that impressive 4-pole switch on the backside for?
I'm planning to use it for a cross-feed. There's enough room at the back of the case.
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post #118 of 760
2/26/05 at 5:29pm

Mk2

Alick,

Looks good - is that a monarchy super dac you are using? Do you take a digital output from a transport feed it into the dac and then into the headamp? I am curious as one of the things I have discussed with Dr White is building in a dac into the headamp so my portable would just be used as a transport and knock the sound quality up another notch. I did look at a few portable dacs and dac daughterboards - have you any experience in this area?

I look foreward to hearing your results!

Nick.
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post #119 of 760
2/26/05 at 5:47pm
It's an M-Audio SuperDAC 2496. It's a failrly well respected (semi)-pro product and it works very well in a domestic environment IMHO. I looked around for ages for a DAC to use with my wireless Squeezebox and nearly settled on the Art DI/O, before I stumbled on some reviews for the M-Audio. I don't use a CD transport anymore. My system uses FLAC files streamed wirelessly to the Squeezebox. It works extremely well and sound great to my ears. I was also considering the April Music Stello DP200 DAC/Pre/Headphone Amp , but it was £800 and they didn't have UK distribution set up when I was buying.
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post #120 of 760
2/26/05 at 6:00pm

dac

Thanks,

I saw the m-audio a while back too. It looked like a high performance no nonsense sort of product. I haven't really caught onto the digital age yet... I have just a 100 CDs and 2000 vinyl! So all these file streaming and wireless audio developments have passed me by a bit. Think I will stick with my deck for the time being . I plan dual use for my headamp - attach to the WNA volco for use at home or attach to my portable for in the gym. I already have a Pink Triangle dac at home so I wanted something portable and battery powered for the gym use. I have seen some dac daughterboards online, like the piccolo. Could the monarchy be used from a battery supply? i.e. is it powered via a plug in dc adapter?

Nick.
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