New! WNA MKll Head-amp kit. - Page 6

optimising the circuit for LM6181

OK,

Back on subject, here is what's necessary to optimise the circuit if you're going to use the LM6181.

R3: Replace with 1K resistor (was originally 3.3K)
R2: Replace with 300R (was originally 1K)

I've done it and the amp is sounding great, I'll let everything warm up for a few hours before saying any more.

Nice one GS keep us posted! Nutty levels sounds gooooooood

Mike.

Yes, same procedure Udo.

As a dedicated headphone amp the WNA is very good with the HD-600 IMO. The Chiarra is a superb sounding headamp and can also be used as a passive preamp Chiarra features here It's a very hard one to call as I love both amps so I'll have to be diplomatic and say both are equally good.

I believe Shaun Williams is now settled in Spain (at last) and business is back to normal...... Williams Hart website so you shouldn't have any problems getting hold of a kit.


Chiarra: Ignore the rock it doesn't come with the kit


WNA: Please note the WNA kit comes supplied with Welwyn RC55Y resistors and EVOX polypropylene caps..... I just used bog standard parts in this pic.

MKl optimising for LM6181

If any MKl owners want to try the LM6181 then the following resistor changes will be necessary:

R2: Remove the existing 1K resistor and replace with a 300R resistor
R3: Remove the existing 3.3K resistor and replace with a 1K resistor

Do this for both channels:

LM6181 impressions

Nice, very nice indeed. The WNA has been playing away with the LM6181 (circuit optimised for it) for a few hours now and I like it a lot. It's virtually identical to the LM6171 except for an added degree of warmth which is very welcome. The LM6171 can sometimes sound slightly anaemic, the LM6181 adds some meat to the bones IMO and brings out the "emotion" in the music.

There's a liquidity and fluidity to the sound which was lacking with the LM6171..... one head-fier classed the LM6171 as "lacking soul" well........ say hello to the LM6181, everything the LM6171 is but with added soul! This puppy has managed to get the hairs on the back of my neck to stand up a couple of times today (listening to Roger Waters "in the flesh" shine on you crazy diamond) awesome stuff! The LM6171 never managed that so I'll have to declare the LM6181 the winner IMO.... "the chip that makes the hairs on the back of your neck stand up!"

Thanks to biovizier for bringing this chip to the attention of Dr. White and fellow WNA'ers.. much appreciated Nick.

The R3 resistor value is spot on but I'll be reducing the R2 (300R) value to around 260R to increase the gain a tad....... it's a bit low for me with 300R. I'm having to listen at 11 o' clock on the volume control instead of 9 o' clock to acheive the same level of volume..... no big deal and easy to rectify..... 300R is a good starting point.

Finally the added bonus....... the LM6181 is a quid less than the LM6171! It's not often that upgrades are cheaper than their predecessor.

Thanks biovizier.

Mike.

not any longer, thanks for pointing that out Steve.

Sure do recall it WNA gain settings are explained here

Haven't looked around as yet Steve but they are available from WNA at £2.50 a pop I believe.

Haven't tried an LM6181 in the splitter as yet will get around to that next weekend.

likewise Steve.

Alick,

Fit the LM6181 in from scratch substituting R2 and R3 with the recommended values...... I'd go for 250R for R2.

This is one very good sounding chip indeed.

Mike.

It's a superb chip for use in the WNA circuit........ no doubt.

Next week will probably focus on the value of R2.......... IMO 300R isn't low enough......... 220R - 250R is the range I'm looking at (My money would be on 250R "215R being optimum for me" )

As it stands the LM6181 sounds better than the LM6171 by a whisker.

Mike.

I've been messing about with the value of R2 with the LM6181 on board and 260R seems a pretty good value for me and is similar to the gain the LM6171 had with R2 being 1K. The recommended 300R starting point gives a good control on the volco but 260R has got a better feel to it for my tastes.

The WNA with LM6181 has been playing for about 100 hours non stop now and I don't think I'll be retrofitting the LM6171. As mentioned before, the LM6181 does everything the LM6171 did but with a bit more warmth and emotion..... it's here to stay. I haven't heard back from Dr. White with his opinions of the LM6181 and can't wait to hear which one of the 2 opamps he prefers.

Not a lot left to do with the WNA now apart from changing the caps and resistors..... I did say at the beginning of the thread that if the amp sounds incredible with standard parts then I'd replace them with more exotic components........ well it does so I will!

Mike.