Circuit advice needed

[Artie]

Just my humble opinion, that Im sure no-one will even bother to read

I read every word . . . and I believe you.

The reason I'm building the little headphone amp is to give a little boost to a walkman-style CD player that I use sometimes when laying in bed, or at work. I just need a little more power . . .

[zaphod_phil]

Hmmm, I have an MS-1 and it's not a bad little amp (emphasize little) as transistor amps go. I've even played a bass guitar through it! I don't know how different the MS-2 is from it. But you're right you should buy the bits and build one yourself, rather than pay seven times more from a store. Hey, Artie, I just thought you were just looking for an easy project to start with - didn't realize you were trying to boost your CD player....

[Artie]

Actually, there's two sides to this project. On one hand, I want to see what an inexpensive headphone circuit sounds like. And two, I want to slowly work up to a very high-quality headphone amp, in the league of the stuff thats sold over at HeadRoom. They have some headphone amps that seem to be outrageously priced for what they are. I want to see what I can build that would rival that stuff.

[dc_danman]

you want to work your way up to amazing nice Headphone amps?
After this OP-amp based one, something you must try (if you can get the tubes) is:
a 2x6021 tube amp. a 6021 is a sub-miniture, dual-triode tube. its tiny, but you still need a high B+ and 6.3v heaters. you can have 1 6021 tube dual triode as a pre-amp, and the other one as a self-split power stage, for about half a watt of clean power, or you could use 1 half of 1 tube as a pre-amp and the other as one of those crazy fender style PI's, that only use 1 triode, and the other tube as a power amp, maybe .8 watts of power for that...
I'd love to do it, only I cant get low enough power TX's, although I may have a decent enough one in my hafler t2 tube pre-amp..... naw, Im to busy atm, with other things

[loverocker]

I'd love to do it, only I cant get low enough power TX's, although I may have a decent enough one in my hafler t2 tube pre-amp..... naw, Im to busy atm, with other things

Well, if you're too busy... but if you're not, the way to get the heater supply and decent B+ for almost no money is to connect two tiny low voltage transformers back to back:
* for UK/Europe it'd be [240V:6V] [6V:240V]
* for USA it'd be [110V:6V] [6V:240V]

So, you take the heater supply from the 6V connection in the middle and the B+ from the end. The second PT can be *very* low VA because it's supplying very low current. Cheap as chips!

[dc_danman]

If you knew what I was working on at the moment, you would know that there is no chance I could make this
I will tell everyone when its done, I just dont want to jynx it by telling everyone what it is, like with my 2204. I think I got to ahead of myself. In the end I just didn't finish it.
I will start a very low power project (.5 to 1 watt) after this, I think. we'll see..

[loverocker]

I will tell everyone when its done, I just dont want to jynx it by telling everyone what it is

hehe I understand exactly what you mean. My current 18Wer has some 'extras' that I'm keeping schtum about until I fix the SNAFUs that I fully expect will bite me when I build it...

[Artie]

Here's another headphone driver that uses the NE5532/34 chip that I found over at Jensen Transformers, makers of high quality audio transformers, (small signal type). This circuit uses a National Semiconductor LM6325 as a current buffer apparently to increase output.

Edit: Removed image to save forum bandwidth, also since it appears that the LM6325 is a discontinued device with no substitute available.

Here's the link to Jensen Transformers:

Jensen Transformers

Scroll down to "schematics" and then scroll all the way down 'til you find "as044.pdf"

Here's the LM6125 data sheet:

National Semiconductor LM6125