[Alick]

I'm pretty sure that the WNA case is not a Hammond. Most people built their WNAs into Hammond cases before the cased kit was launched, but the "official" case doesn't look like any Hammond I've seen. (Pink Floyd probably has a better picture of the case and an idea of its provenance).

 

[PinkFloyd]

Quote:

Originally Posted by Alick I'm pretty sure that the WNA case is not a Hammond. Most people built their WNAs into Hammond cases before the cased kit was launched, but the "official" case doesn't look like any Hammond I've seen. (Pink Floyd probably has a better picture of the case and an idea of it's provenance).

Hi Alick,

The WNA enclosures are similar to the ones found at Maplins they are far from "exotic" but they are a good size and David uses them because they come in a very wide range of sizes that happen to suit the sizes of his pcbs very well. He sends them off to be black anodised and he says this makes them almost scratch proof.

The Hammond is a much nicer looking enclosure, the WNA one is industrious looking and serves a purpose but all the money has been put into the sound end of the amp and not into cosmetics.

The black Hammond looks very good and far less common looking than all those aluminium ones you see everywhere you look

Mike.

PS: I believe David sells these anodised enclosures, ask him for the current price.

 

[PinkFloyd]

Cracked it!

Fitted 2 x Cerafine 220uF in C3 & C5 and the amp oscillated causing TR3 & TR4 to heat up..... I replaced the LM6171 in IC2 with a OPA134 and the oscillation disappeared.

I'd run out of 25V 220uF Cerafines so had fitted "35V" 220uF Cerafines instead.... I wondered if the higher voltage rating caps could be causing the rail splitter LM6171 opamp to oscillate......

It was out with the 35V 220uF cerafines and in with 2 x 25V 220uF cerafines I poached from another amp...... no oscillation at all with the lower voltage caps.

So, it appears the LM6171 prefers low voltage caps in C3 & C5.... probably 16V would be the ideal voltage rated cap to use.... you can safely use larger voltage caps in C3 & C5 if you're using an alternative to the LM6171 in IC2, I tried some 470uF 35V cerafines in C3 & C5 with an AD825 in the rail splitter and it works perfectly... roll in the LM6171 and "bingo" prepare for heat from TR3 & TR4.

I'm glad I found this out as these random oscillation gremlins have been really hard to pinpoint..... keep C3 & C5 below 25V and there should be no probs I reckon it would be a good idea to avoid low impedance caps in C3 & C5 also.

 

[Sewer Guy]

Hi Pinkie & all WNA'ers. As you know I have used the LM 6171's quite a bit both personally & at work. There should be no problem using them as audio amplifiers & line drivers for both audio & baseband video.

I do question its use in a rail splitter application, its wide bandwidth & high slew rate could definitely contribute to instability in that configuration. It would be better to use a TL082 or other equivalent device as the rail splitter.

I have been following this thread with interest. Keep up the good work.

 

[PinkFloyd]

Quote:

Originally Posted by Sewer Guy Hi Pinkie & all WNA'ers. As you know I have used the LM 6171's quite a bit both personally & at work. There should be no problem using them as audio amplifiers & line drivers for both audio & baseband video. I do question its use in a rail splitter application, its wide bandwidth & high slew rate could definitely contribute to instability in that configuration. It would be better to use a TL082 or other equivalent device as the rail splitter. I have been following this thread with interest. Keep up the good work.

Hi Bill,

Long time no see, good to have you back

I know you are an absolute expert on the LM6171 so really welcome your advice re: using them in the rail splitter section. Apart from the TL082 are there any others you could recommend? To date all the following have worked without glitch: OPA134, AD825, AD8065 and OPA627... any others you could add to this list? The rail splitter op amp does have an effect on the sound but maybe the LM6171 is just a tad "too" fast.. it sounded great with OPA627 and AD825.... is there anything else along those lines that you'd recommend or would you just stick with TL082 ?

Good to see you back mate!

All the best.

Mike.

Edit: Just checked, TLO82 available from Rapid for 38pence each

 

[Alick]

Quote:

Cracked it!

Well done Sherlock!

(Maybe I should rethink rolling that LM6171 into the rail splitter...)

 

[PinkFloyd]

Quote:

Originally Posted by Alick Well done Sherlock! (Maybe I should rethink rolling that LM6171 into the rail splitter...)

May be a good idea Alick... try it, if it works then all's well. I'm listening right now with an AD-825 in the rail splitter and I do believe there's a slight degree more warmth to the proceedings... all the same speed and attack of the LM6171 trio but with a tad more warmth, maybe due to the fact I've got a slight cold however

It could also be a mixture of the AD and LM signatures giving you the best of both sounds but maybe that's a bit far fetched..... you never know though

Over the hoilday period I'm going to really try a wide variety of different components into the PCB to see what effect different brands etc. has on the sound..... the AD-811 will be here on the 28th so that'll be first under the bonnet! One thing's for sure.... fitting 8 ohm resistors instead of the 10R resistors in R7 and R8 has brought about a good 20% increase in grunt making the amp sound a good bit more ballsy and if these AD-811's are all they're cracked up to be then they'll turn the amp into a bass powerhouse..... not to everyone's taste but may suit Grado owners

Why not build up another amp Alick? I'm getting addicted to soldering again..... not good

I've also found it's a lot easier if you make the amp up in modules ie:

Prepare the potentiometer with the cabling ready to solder onto the phono sockets and board.

Fit the headsocket with the dummy resistors and caps ready to install.

Wire up the board with the power wire, output cables and Led on a length of wire.

It all slots together a lot easier. I've also got into hot glueing the wires on top of the board (where they enter the holes to be soldered) to ensure there is no way they can move... I also hot glue the headsocket "module" the beauty of the hot glue is that it provides excellent strain relief and should it become necessary to service the amp at any time it's easy to pick off.... I totally seal the headsocket "module" so it would have to be replaced with a new module if any part of it were to fail over the years but it's as cheap as chips to make one up so no worries.

Anyways, enough on my new glue gun... it's almost as addictive as soldering

 

[Jan Meier]

Dear Headfellows,

Do you guys know that there are headphone amps on the market that:

- Use the LM6171
- Use fast capacitors throughout and yet are stable.
- Do not use coupling capacitors as offset problems are eliminated by appropriate circuitry
- Have crossfeed on board

???

The circuitry of the simplest version of these amps can be found at:

http://home.t-online.de/home/meier-audio/headamp.htm

Cheers,

Jan

 

[PinkFloyd]

Edit: I must check links before commenting on the content of a webpage.

Quote:

Originally Posted by Jan Meier Do you guys know that there are headphone amps on the market that: - Use the LM6171 - Use fast capacitors throughout and yet are stable. - Do not use coupling capacitors as offset problems are eliminated by appropriate circuitry - Have crossfeed on board ???

Yes, perfectly aware of your DIY design Jan but I love the sound of the WNA. It's first class and Dr. White has really managed to design an amp which suits my ears.. it's very British sounding with regard to spot on timing, refinement and neutrality and I luv it

He also utilises the full speed of the LM6171 which is why the seperation and clarity are just so fabulous IMO.

There are no issues with the WNA kit amp just a few people have experienced the odd instance of oscillation when using non standard caps........ easy enough to work round

On reflection I'm not too sure I'd want crossfeed in the WNA, the sound is absolutely crystal clear and not at all fatigueing so there's not much use for it unless you want to tidy up extreme stereo recordings... plus it means a switch in the signal path which isn't good news. The standalone crossfeed is excellent and I use it on the very rare occasions when I listen to some of the Beatles extreme recordings.

 

[Alick]

Quote:

not to everyone's taste but may suit Grado owners

My HD650's have arrived, so I've a foot in both camps these days.

Quote:

Why not build up another amp Alick? I'm getting addicted to soldering again..... not good

Mmmm, just what I was thinking. I'm rewiring the WNA over christmas, but then I'll need something else to play with. I was thinking of getting the complete WNA kit but, since I have a WNA already, maybe I'll think about giving Jan's circuit a try so we can compare and contrast. Jan - is there a PCB available for the amp in the link or do folks build it up on stripboard?

 

[Duncan]

Quote:

Originally Posted by PinkFloyd Over the hoilday period I'm going to really try a wide variety of different components into the PCB to see what effect different brands etc. has on the sound..... the AD-811 will be here on the 28th so that'll be first under the bonnet! One thing's for sure.... fitting 8 ohm resistors instead of the 10R resistors in R7 and R8 has brought about a good 20% increase in grunt making the amp sound a good bit more ballsy and if these AD-811's are all they're cracked up to be then they'll turn the amp into a bass powerhouse..... not to everyone's taste but may suit Grado owners

Having replaced the LM6171 with an OPA627 I can say very conclusively that the perceived sound quality has improved substantially (using the RS1s)

I'm not sure if I myself would want any more bass than what is on offer... I guess I won't know until I try lol, but - as 'stock', the bass is incredibly tuneful with the RS1, so I cannot see a requirement for more...

Hopefully getting a new solder station today, so if I get that, it'd only be a 20 second job to swap them... might be worth a try I suppose

 

[Alick]

Quote:

Having replaced the LM6171 with an OPA627 I can say very conclusively that the perceived sound quality has improved substantially (using the RS1s)

Duncan; did you replace the rail splitter op-amp or the ones in the audio path?

 

[Duncan]

Quote:

Originally Posted by Alick Duncan; did you replace the rail splitter op-amp or the ones in the audio path?

Sorry, should've made that clearer... is just the rail splitter

 

[jude]

Quote:

Originally Posted by PinkFloyd ....Thing is, Dr. White's circuit sounds out of this world and the "price" has to be the head-fi bargain of the century..... Your amps may / may not come close to the performance of his amp but your prices are way too heavy for the DIYer to comprehend...... Instead of blatantly marketing your amp in this superb thread maybe you can chip in with your experience of the LM6171 and contribute to it with your ideas...... that would be most welcome Jan. Please remember this is the DIY forum

Mike, did you actually read the page that Jan linked to? I checked the link provided by Jan, and it is a project page that provides useful information on the LM6171, as well as schematics germane to his discussion in that article that does, as you asked for, "chip in" with his experience with the LM6171.

 

[PinkFloyd]

Quote:

Originally Posted by jude Mike, did you actually read the page that Jan linked to? I checked the link provided by Jan, and it is a project page that provides useful information on the LM6171, as well as schematics germane to his discussion in that article that does, as you asked for, "chip in" with his experience with the LM6171.

No Jude I didn't read the page I wrongly assumed it was a link to a commercial amp, apologies to Jan my mistake.