Aspen Headphone Amp

[keantoken]

I've suggested a 2SC3423 VAS, but no one has commented on that yet. I wonder how much it matters, really, the circuit already performs so well. Any second opinions?

- keantoken

[AKSA]

Kean,

Can't really see the point of the 3423 - it's hard to get and rated to 120V, which is wasted here. The device chosen has very low Cob, is running at just 4.25mA, and easily obtainable. Can you think of a good reason?

Hugh

[keantoken]

Makes sense. The perfectionist in me though has suggested to use the 2N4124 here however; compare the Cob curves.

http://www.jaycar.com.au/images_uploaded/BC558.PDF
http://www.fairchildsemi.com/ds/MM/MMBT4124.pdf

Pulling teeth?

- keantoken

[AKSA]

Looks good, I agree, nice fast device at 300MHz and quiet......

BUT, more difficult to find, Cob 4pF versus 6pF for the BC557, beta no higher.

However, I did note that the BC560 had 2db of noise compared to the 10dB of the BC557, so maybe we should use that? Easy to find, very good noise performance, all other parameters comparable or better than the 557!

Thanks, Kean, good suggestion....

Hugh

[Nico Ras]

John, unlike yourself, I try not to make people look stupid. I go with someone who is new at something I will be new to it as well, I find it makes it a lot easier coaching, without telling, this is fortunately is my way of getting something across.

Also unlike yourself I did not progress from being a handyman to obtaining an electronic engineering degree through DIY audio.

In the past I had nothing but good things to say about John, but unlike him I do not need this forum to have a gripe at life.

I still have a very comfortable life and a few successful electronic engineering companies. I have enjoyed my hobby for the best part of my life and will continue to do so without DIY audio. I need not share anything, but I did because I wanted to, not because I had to.

Most of my life I attempt to be as humble as possible I never wanted to be perceived as superior. If I did so then I apologies to all.

Cheers all, and nice knowing you John.

[keantoken]

We could use the MPSA18. 3pF Ccb, with 1.5db noise. And high Hfe.

http://www.fairchildsemi.com/ds/MP/MPSA18.pdf

Nico, please ignore John. We know enough not to take his personal comments seriously. If he attacks you and doesn't get a response, it makes him look bad, not you.

- keantoken

[AKSA]

Nico,

Please, stay with us. I speak for all here when I say that we hold you in the highest regard, not just for your knowledge, which is encyclopaedic, but for your willingness to explain carefully to others some of the finer points of electronics, a difficult endeavour - in short, to give willingly of your time and help others. John made mistakes, sure, but he tells me he would like to leave, and if that is the case, this unpleasantness is now behind us.

Folks, I cannot believe the time Nico has spent with me, explaining, encouraging, suggesting, and he has even rung me on several occasions to chat about electronics. I consider him a noble and kind friend, and I'm grateful I met him here. I believe we all are. To lose him would be a tragedy for the thread and a severe loss to DIYaudio.

To give John his credit, he is knowledgeable, generous with his circuits, and very energetic. He is welcome to stay with us but only if he immediately stops attacking the experience and beliefs of others. I resile from nothing I have said to you, John, either here or privately, you have been disruptive, and you have caused a lot of angst for others.

So, back to normal programming, MPSA18 looks good, Nico, what are your thoughts on this device? Perhaps a simulation would reveal any improvements? We have a short signal path, so a bit more feedback shouldn't hurt a bit......

Cheers,

Hugh

[keantoken]

Here's the schematic for quick reference...



- keantoken

[MJL21193]

Originally Posted by AKSA

To give John his credit,

Upfront and honest too.



Immortalized

[Bigun]

Hugh - I will email you offline.

Moderators - I respectfully suggest that some of the posts above contain off topic comments that can be safely removed without hurting the flow of this thread with the benefit of leaving a better record for readers who follow us.