74HCU04 portable headamp

[tropicalrips 0]

does the dual supply design provide more current to the ground channel? i also not EE trained

[heady 0]

tropical, I don't know but almost all the schematics for op-amps I have seen was for dual power supply. And I thought this design was great because it needed a single power supply only. Perhaps one of the DIYers who are EE trained can explain. Thanks.

[heady 0]

I have built another amp with the same schematic, using a dual -1.2 -0- +1.2V power supply. Using ordinary Sanyo 1000uF caps as output cap. And it works very well with my Grado SR60 now. Thanks to firefox for the suggestion to use the 1000uF caps.

 

Hmm... I like the sound even if it is not as detailed as the Pimeta. The difference is probably not noticeable on MP3 playback.

 

Anyone knows where I can get smaller 1uF polypropylene caps, smaller than the Rifa/Evox 1uF/250V caps that is.

 

Thanks.

[heady 0]

Update -

Yet another friend ask for a headamp and I use this opportunity to use Nichicon FineGold 470uF 10V as the output caps. Wow, it changed the sound to really clear and airy. Very good, pity the only Nichicon FineGold 1000uF are 63V and are humongous. Anyway, the new amp still sounds good with my Grado SR60. I really enjoy the Grado, really value for money.

[Username 0]

Heady, where did you find the schematics? Thanks!

 

[heady 0]

Heady, where did you find the schematics? Thanks!

The schematic came from Sijosae (http://www.headphoneamp.co.kr/bbs/zboard.php?id=diy_sijosae&no=188). I got the resistors value for gain of 7 from a DIYer on headfi. I made the layout for using the striped traces perf board myself.

 

Problem with my layout is, with the polypropylene caps I can get, it won't fit into the Hudson tins we can get here. It fits the Altoid tins not available in SG. To fit into the Hudson tins, I can only find Evox polyester caps which is small enough. I will publish my layout later in this thread.

 

Regards.

[heady 0]

Here is a picture of the layout to fit into Altoid tin. If you need higher definition pdf file, pm me your e-mail address and I will send you the file. I will send the other layout for Hudson tin when I finish it.

Edited March 15, 2005 by heady

[heady 0]

** UPDATE **

I listened to the PAv2 amp on Sunday and was impressed with the sound quality. I noticed that it used electrolytic caps for both input and output decoupling. Seems to be against standard belief that polypropylene is best.

 

As an experiment, I took out my 1uF polypropylene caps used for decoupling the input and put in Nichicons 470uF 10V electrolytic caps instead. The sound immediately opened up, the triangles and high-hats in drumset sound so much better and the high frequency roll off has disappeared.

 

Again, I am not EE guy so I cannot explain this except it alters the input filter but it sure sounds a lot clearer and more acceptable.

 

Any experts care to explain? Also, if you have the time, try to built this amp, I think it is so low cost and easy to built, it is fun!

 

[Firefox 0]

As an experiment, I took out my 1uF polypropylene caps used for decoupling the input and put in Nichicons 470uF 10V electrolytic caps instead. The sound immediately opened up, the triangles and high-hats in drumset sound so much better and the high frequency roll off has disappeared.

 

Again, I am not EE guy so I cannot explain this except it alters the input filter but it sure sounds a lot clearer and more acceptable.

 

Any experts care to explain? Also, if you have the time, try to built this amp, I think it is so low cost and easy to built, it is fun!

The Rifa's are dark sounding...

Nichicon Muse FA & Finegolds are brighter and more bass heavy.. Hence, the difference in sound..

Edited March 21, 2005 by Firefox

[heady 0]

The Rifa's are dark sounding...

Nichicon Muse FA & Finegolds are brighter and more bass heavy.. Hence, the difference in sound..

Thanks, didn't realise that. Will you be able to know how Oscon caps sound compared to the Nichicon FineGolds? I can't find a small sized Nichicon cap in values larger than 470uF. I found the Nichicon FineGold sound good straight off without running in, maybe that's why they are popular.

 

Thanks again Firefox.

[kwhv 0]

 

 

Hi everyone,

 

May I know where to get the nichicon fine gold or FA caps? Thanks.

[heady 0]

 

 

Hi everyone,

 

May I know where to get the nichicon fine gold or FA caps? Thanks.

Koba electronics at People's Park Centre, 4th level.

[xchagg 0]

A couple of questions:

 

Does using premuim capacitors for the power supply capacitors influence the sound? Cause I used those Nichicon FineGolds in my CMOY2 and after around a week (avg 4hrs per day), the sound suddenly became brighter, as if the treble eq had been bumped up a notch. The change was quite sudden: was waiting for the MRT when I noticed something funny with the sound haha.

 

WRT using electrolytics instead of film caps for input/output?? decoupling, would this be like using a good quality electrolytic, e.g Black Gate N-series for the C4 cap in a Pimeta? Or the C3, C4, C5 in a CMOY2? (hand feeling itchy already haha).

 

And finally what exactly is the function of the input coupling cap and output coupling cap?

 

Input coupling: Blocking DC offset? Is this cap usually in the audio signal line?

Output Coupling: umm, no idea Is this cap usually in the audio signal line?

 

Thanks.

[jasonhanjk 0]

How much uF you use for the input coupling?

[Username 0]

I notice that this is a bump. Sorwie.

Edited July 21, 2005 by Username