Marsh headphone amp from Linear Audio

If all is needed is a buffer, then what's wrong with the classic diamond buffer? I think it's really awesome.

I'm not Richard, of course, but what's wrong with trying something different that works equally well, or even better? I've been loving diamond buffers since the first time I saw the LH0002 schematics, but Richard's buffer is as elegant and simple as the DB, and its figures are quite amazing.

L.
 
I'm not Richard, of course, but what's wrong with trying something different that works equally well, or even better? I've been loving diamond buffers since the first time I saw the LH0002 schematics, but Richard's buffer is as elegant and simple as the DB, and its figures are quite amazing.

L.

Because this isn't about "flavor of the week". It's about what works. To me, this is engineering, not fashion.
 
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Joined 2006
There is both a buffer and a 12db gain stage. This is why you need the article. not to make money but to explain what is going on best.

I was thinking that the circuit being discussed as in post 1 could do this, so there is even more parts involved. This unless you see the last CFP pairs as a buffer which I dont in my point of view. Too complicated then for what it can do, like I mentioned before JLHs design can do same or better and is less complex.
Its not difficult to do minor changes to give the circuit in post 6 voltage gain, have the kind of performance described and (there is more than one way), its basic stuff and already done ages ago.

I have nothing against Linear Audio btw but I can see some reason behind the commercial argument made here. This has come up a few times in the forum but resolution is not easy on this topic.
 
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Joined 2012
I was thinking that the circuit being discussed as in post 1 could do this, so there is even more parts involved. This unless you see the last CFP pairs as a buffer which I dont in my point of view. Too complicated then for what it can do, like I mentioned before JLHs design can do same or better and is less complex.
Its not difficult to do minor changes to give the circuit in post 6 voltage gain, have the kind of performance described and (there is more than one way), its basic stuff and already done ages ago.

I have nothing against Linear Audio btw but I can see some reason behind the commercial argument made here. This has come up a few times in the forum but resolution is not easy on this topic.
Interesting attitude.
 
AX tech editor
Joined 2002
Paid Member

I agree wholeheartedly. LA hasn't created the bad vibe, its quite blameless (in the everyday meaning of that word!). I freely acknowledge my share of the blame for the bad vibe, and I apologise for that.

Thank you!


As RNMarsh seems to acknowledge in post #80, Linear Audio is a commercial concern - nothing wrong with that at all.

I got the idea for Linear Audio in 2009 at the European Triode Festival, when discussing audio pubs in general and lamenting their disappearance. Since I always seem to be the sucker at such occasions (and/or the guy who drinks too much), I took euro 20k from my retirement fund and started Linear Audio.
By now, it seems to be able to pay for itself. Whether I ever get back my euro 20k - who knows?

You may have noted that I take one article from each issue and put it online for free, as soon as a new issue is published. But LA is a printed issue because I personally like printed books, I like to have them at my side, open where I am, and leaf up and down the pages to check things, enjoy the smell of ink. Unfortunately, that doesn't come for free. And it would be very disrespectfull of me to people who pay for LA if all the contents would be available elsewhere for free.
It is something the whole publishing world is grappling with. It's a risk I take - if all content is stolen, and nobody buys anymore, I'm [starts with an f and ends with ucked].
BTW Linear Audio does have it's own thread here but that's more admin in nature - obviously I can't have a thread that shows all LA content.

What I find interesting is that people are willing to shell out $ 100 for a boutique cap on a simple "I did, and it's great, sound stage has never been as good"- type post, but have issues with getting a printed book for $ 28 that REALLY can advance them in understanding what it is they are doing. Very few appreciate the knowledge and insight people like Scott Wurcer and Dick Marsh put in their articles, and they will never appreciate and understand it from a scanned circuit diagram. One of the few riddles in life I still have to solve ;)

jan didden
editor/publisher
Linear Audio
 
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Thank you!...


What I find interesting is that people are willing to shell out $ 100 for a boutique cap on a simple "I did, and it's great, sound stage has never been as good"- type post, but have issues with getting a printed book for $ 28 that REALLY can advance them in understanding what it is they are doing. ...

jan didden
editor/publisher
Linear Audio

Jan,

You have made an assumption that is clearly not the case. There are several cases you might want to consider:

1. There really are folks here who spend almost no money as their budgets are limited.

2. It just might be possible there are Ego's hanging out here that are larger than mine and so don't recognize the advantage of reading others contributions.

3. There are those who as long as the milk is free, won't buy a cow. So what if the milk is a bit sour (Or the content is not at as high a standard.)

4. Then there are folks like me. I won't buy any new printed content when I don't have time or room for it. I'll buy material when things slow down! I still need to build 6 to 10 more bookshelves!

5. Then there those who are here to primarily show off. You for some strange reason assume that everyone who writes they have a Royce really does. Painting RR on the hood of a Yugo just isn't the same.

6. Finally there are some who just want to build stuff and there are lots of free projects. They don't get that some of the designs are really not very good.

Oh I just re-read #2, My mistake there can't be Egos larger than mine!

ES

Now as proof just look at some of the comments on the circuit discussed here by folks who have not seen the article, don't know the author's history and generally don't have a ticket to the clue train. (Currently found in ant issue of L.A.)
 
AX tech editor
Joined 2002
Paid Member
Sure Ed, all good points.

I didn't per se literally mean chosing a $ 100 cap for an LA volume, rather I wanted to contrast the easy spending on parts without iron clad reasons, versus spending something on increasing your understanding.

I'm sure you'd agree on that in principle.
Now if you'll excuse me, I must go paint 'Lotus' on my Chevy Cruze...

jan
 
Sure Ed, all good points.

I didn't per se literally mean chosing a $ 100 cap for an LA volume, rather I wanted to contrast the easy spending on parts without iron clad reasons, versus spending something on increasing your understanding.

I'm sure you'd agree on that in principle.
Now if you'll excuse me, I must go paint 'Lotus' on my Chevy Cruze...

jan

Just leave the hood up and parts scattered around. It will look just like the real thing!
 
Guys, we're talking about an open-loop small-power buffer capable of 0.001% THD into 30 ohm - it seems there's quite a lot of good engineering behind these figures...

L.

So, is 0.0007% good enough? Four transistors and two diodes (which may count as transistors since they are CRD's). Since there is no loop feedback to reduce the output impedance, then you really have to juice it up to get a low enough impedance to drive 30 ohms at low distortion. Output level is 731mV rms. At 1V rms output, distortion goes up to 0.001%. This is across 30 ohms of course, as you wanted. These are Mr. Cordell's transistor spice models, btw.
 

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So, is 0.0007% good enough? Four transistors and two diodes (which may count as transistors since they are CRD's). Since there is no loop feedback to reduce the output impedance, then you really have to juice it up to get a low enough impedance to drive 30 ohms at low distortion. Output level is 731mV rms. At 1V rms output, distortion goes up to 0.001%. This is across 30 ohms of course, as you wanted. These are Mr. Cordell's transistor spice models, btw.

Now run a variation of parameters.