Marsh headphone amp from Linear Audio

Who sells the pcb, Jan?

I am selling the pcb's at cost -- actually a little below cost as I made a mistake in the price estimate before i sent the Gerber files out. I don't believe it's equitable to profit off Marsh's intellectual property. This way a lot of folks will build his device.

Benefit to me is that my cost for a board is only a few dollars, instead of $60 if i sent it out. I did the same thing with two of SY's designs.
 
Just dropped by to say Hi to this forum. Got questions?

:)

What did you use as the source resistors - R3,4 - 47 ohms seemed best to me. I ran the amp for 5 hours and offset changed by only a couple mV.

I only had a dozen or so of the MJE200/210 so rushed to solder it up without matching the output devices, and the results were really excellent for my "pro forma" sennheiser hd-650 impedance of 300 ohms.
 
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51.1 Ohms. The excellent thermal drift is due to the topology.... something i dont think most people appreciate and few of the circuits seen here can match without a dc servo (A concept I introduced to the world). You'll get sota distortion numbers if you match all devices. I hope others will buy the issue from LinearAudio for the explanations of this deceptively simple and cheap circuit. It's all in the topology as I think John Curl has said.
 
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As this buffer shown in the article is one of the derivatives in the article moving towards the final circuit and not intended for diy building - note it will probably smoke the Q1/Q2 unless you put series resistors in their emittters.
 
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Hello! I still love your article about capacitors!
That developed out of listening tests done first by my friend Peter Moncrief of IAR which got me to wondering-- what is it about a capacitor that could make them sound the way he described? The research i did first came out in bits and pieces in TAS LTE until Walt Jung contacted me to do a article on the whole subject.
 
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From Volume 3 of "Linear Audio". It sims out very well. Here's a possible PCB 3D image:.........

I fail to see the point of posting "a possible PCB 3D image" for a circuit you're not posting. Free advertising for "Linear Audio", but what purpose does it serve diyaudio members? Why not just say "I've built this headphone amp featured in Linear Audio, I think it's great, I'm having some boards made which I'll sell at cost, get in touch if you want one" ?

Oh, sorry, you haven't built it yet, have you? Just simmed it. And without having put together a working prototype, you're posting possible PCB 3D images. Faith-based audio then. Look at the nice relaxing images, you can hear it already.

OK. I guess that means I have to buy the magazine (or article?) in order to understand this circuit. Thanks.

Yes you will Dirk, but I'm sure you'll find that
the result is something along the lines of "excellent detail with a smooth and sweet presentation".

You can find the schematic via LinearAudio. You cant get the full flavor nor learn the extras by just looking at a schematic. There is more in the article.

I hope it's a smooth and sweet flavour. And I'm sure the extras are quite wonderful, really.

Perhaps it might be more appropriate for this discussion to be hosted by Linear Audio? It does now seem to be a full blown puff for that publication. Your post consisting only of a quote of your earlier post is certainly consistent with that.



 
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I fail to see the point of posting "a possible PCB 3D image" for a circuit you're not posting. Free advertising for "Linear Audio", but what purpose does it serve diyaudio members? Why not just say "I've built this headphone amp featured in Linear Audio, I think it's great, I'm having some boards made which I'll sell at cost, get in touch if you want one" ?

Oh, sorry, you haven't built it yet, have you? Just simmed it. And without having put together a working prototype, you're posting possible PCB 3D images. Faith-based audio then. Look at the nice relaxing images, you can hear it already.


Yes you will Dirk, but I'm sure you'll find that
the result is something along the lines of "excellent detail with a smooth and sweet presentation".


I hope it's a smooth and sweet flavour. And I'm sure the extras are quite wonderful, really.

Perhaps it might be more appropriate for this discussion to be hosted by Linear Audio? It does now seem to be a full blown puff for that publication.




I'm not interested enough to buy the magazine or what ever. I'll figure it out when I get around to it. This isn't wine we are talking about, so your use of those words doesn't mean much to me. I can't hear well enough to understand what you're talking about anyway.
 
I'm not interested enough to buy the magazine or what ever. I'll figure it out when I get around to it. This isn't wine we are talking about, so your use of those words doesn't mean much to me. I can't hear well enough to understand what you're talking about anyway.

Actually I was being a bit tongue in cheek Dirk, and quoting from a description used in the promotion of Mr Marsh's Multicaps - 1uF, 100v, $23.39 - you know you need them, though fortunately not for this headphone amp it seems.

I know we say stuff tongue-in-cheek and ironically much more
this side of the pond than on yours, my apologies for failing to allow for that.

I agree with you wholeheartedly that this isn't wine. Though I should point out that even professional wine tasters tend to do rather badly on the rare occasions they take part in blind testing....:D....funny that eh?
 

Actually I was being a bit tongue in cheek Dirk, and quoting from a description used in the promotion of Mr Marsh's Multicaps - 1uF, 100v, $23.39 - you know you need them, though fortunately not for this headphone amp it seems.

I know we say stuff tongue-in-cheek and ironically much more
this side of the pond than on yours, my apologies for failing to allow for that.

I agree with you wholeheartedly that this isn't wine. Though I should point out that even professional wine tasters tend to do rather badly on the rare occasions they take part in blind testing....:D....funny that eh?

Interesting comments considering the blatant commercialism that's tolerated here regularly. Professional wine tasters take part in no peeking blind tastings all the time and some do rather well. Difference vs preference just keeps being ignored.
 
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Actually I was being a bit tongue in cheek Dirk, and quoting from a description used in the promotion of Mr Marsh's Multicaps - 1uF, 100v, $23.39 - you know you need them, though fortunately not for this headphone amp it seems.

I know we say stuff tongue-in-cheek and ironically much more
this side of the pond than on yours, my apologies for failing to allow for that.

I agree with you wholeheartedly that this isn't wine. Though I should point out that even professional wine tasters tend to do rather badly on the rare occasions they take part in blind testing....:D....funny that eh?

OK, fair enough Simon.

BTW, one of the moderators here is a certified wine taster. Ask him about blind testing if you get the chance.
 
I have personally seen a group of professional wine-tasters fail miserably to distinguish between wines that they had previously claimed to be poles apart, and which differed greatly in price. But I was wrong not to say "some wine tasters", as Scott points out:
Interesting comments considering the blatant commercialism that's tolerated here regularly. Professional wine tasters take part in no peeking blind tastings all the time and some do rather well. Difference vs preference just keeps being ignored.
(my emphasis)

Commercialism is sometimes officially tolerated here in what I'd see as inappropriate places for it, ie the non-vendor sections. Sometimes fun is had when it's particularly hilarious, the silver-sata-saga springs to mind of course. This one doesn't seem funny though, just rather grubby.



 

I fail to see the point of posting "a possible PCB 3D image" for a circuit you're not posting. Free advertising for "Linear Audio", but what purpose does it serve diyaudio members? Why not just say "I've built this headphone amp featured in Linear Audio, I think it's great, I'm having some boards made which I'll sell at cost, get in touch if you want one" ?

Oh, sorry, you haven't built it yet, have you? Just simmed it. And without having put together a working prototype, you're posting possible PCB 3D images. Faith-based audio then. Look at the nice relaxing images, you can hear it already.


I think i had mentioned that i took Dick's design, simulated in Multisim 11 (not 12 which has issues), liked what I saw, transferred the design to Ultiboard and had some boards made up by one of my vendors. Now, here's a real FFT run with a real measurement instrument (not some POS soundcard, an Audio Precision SYS2722) to demonstrate what I experienced.

An externally hosted image should be here but it was not working when we last tested it.


With the milk of human kindness gushing from my breast, I offered the boards at cost and many have taken me up on the offer. It affords me the opportunity of biking the 7 round trip miles to the US Post Office where I can discuss real college football with George. Oh, did i mention that our college football players go to college?

There are 2 articles I keep from "Audio" magazine, Bob Cordell's THD analyzer and the Jung-Marsh article on picking capacitors. Same vintage.