Noir, a two transistor headphone amp: class-A, single ended, 150mA bias

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Very nice build, Fred! Looks like you drilled your own front panel to accommodate the locking headphone jack, but left the stock rear panel in place. And the preamp output RCA jacks are mounted in position, even though you don't have flywires connecting them to the circuit board. Very pretty.
 
help with part substituions

I am putting together my parts list for the Noir pcb's I received as a gift last week.

I prefer ordering from digikey, and have been able to sub most of the parts that were not available.
There are still a couple parts I need to figure out how to substitute.

Can someone just give me a good idea of what to sub for ...
D25, D75: E-153 Current Regulator Diode

LED: Lite-On Led Is there anything special about this, or will any 3mm led do? Digikey says it is in stock, but "A separate quote is required for this product." Not sure what that means.

Lastly, has anyone substituted any of the metal film resistors for carbon comp ones? I need to study the schematic a bit more to understand which ones are in the audio path. (p.s. I am a bit new to transistor based amps)

Thanks for any help.

edit: ugh, looks like i spoke too soo, need to find replacements for Q21, Q71, Q22, Q72, D1 too.
 
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The Semitec E-153 current regulator diode is in stock at Mouser.com (355 pieces on the shelf). Regrettably, Semitec does not distribute thru DigiKey. Double check using Octopart:

link

It's a good idea to use Octopart when searching for components; it will tell you how many pieces are in stock at each distributor.

The important characteristics of the LTL-14CDJN LED are: (1) it's BIDIRECTIONAL; (2) it's in a 3mm "T1" package. Digikey has 3698 pieces of them on the shelf. If you're hoping to save money, Digikey offers the 1125-1183-ND bidirectional LED, for ten cents less.



_
 
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How have I never known about Octopart?? Also, totally forgot to check Newark. Thanks! I think I'm up to 5 different shopping carts for this... time to see if I can consolidate.

I sometimes use Octopart for car parts as well. Newark/Farnell seem to be the only place for the BC516 for now:

https://www.newark.com/search?st=bc516

I saw that Mouser should be getting some in September.
 
I ended up getting everything, except BC516, via ordering across 2 retailers (digikey, mouser). I backordered the BC516 via the same order from Mouser, as the September supply was listed. If I find that part else where before then, I'll post back. I did see it available from one place on oceopart, but was not familiar with the retailer.
 
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I got a Private Message containing the inquiry quoted below. Because I believe the Forum is a much better vehicle for communication with the entire diyAudio membership, I've copied the question here. Anyone and everyone, please accept my invitation to share your insight, thoughts, studied opinions, and casual remarks.

Dear [diyAudio membership],

I found this image on the Forum and am thinking about putting it into a modified Noir hedphone amp circuit. My "quick question" is:

Does the CS pos and CS neg equate to the positive and negative sides of the E153 in the Noir circuit? And does the DC supply = Gnd?

I'll take a look at PSRR enhancement caps and see if I can figure it out. It's been a while since I did actual electronics stuff :eek:

click on the image to see it full size and undistorted:

778137d1567040723-single-class-headphone-amp-using-transistors-t2-mje340_2n5210_37r-png
 
Though I'd share a couple pics of another recently completed Noir. Had fun picking out parts for this, though I think I paid for shipping from four different vendors. Parts are scarce right now. Sounds amazing with my K702s.
 

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Okay folks, question - I was thinking about adding an output buffer (plus summing for 2.1 out) to the amp immediately before the RCA out. Using OPA2134s and a DPB09B-15.

Initial L+R input to the bottom OPA as non-inverting. Then using top OPA as summing and subsequent re-inversion. The DPB09B-15 is a dual 15V isolated PS (300mA/rail).

Anybody see any immediate issues with doing this? I am likely still missing a few caps for smoothing the DPBs output.
 

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I think if you work out the transfer function of the circuit in post #316, it will tell you that in the expression

SubOut = (+1) * CONSTANT * (Lin + Rin)

the number "CONSTANT" is not equal to 1.0. {I could be wrong}

And, oh by the way, I doubt that you actually want CONSTANT=1.0 . Think about a monophonic input having Lin=Rin. Oopsie!
 
Though I'd share a couple pics of another recently completed Noir. Had fun picking out parts for this, though I think I paid for shipping from four different vendors. Parts are scarce right now. Sounds amazing with my K702s.

looks amazing! Did you change any parts from the stock BOM? if so, could you share what you changed and why? I'm looking to experiment with mine to change the sound, and/or build another one with premium parts - and am looking for suggestions on the best possible parts to fit!