Really Quick One: What Type Of Input Cap

[led_zeppelin]

HI...

Just a quickkie

i'm building a rod p3a, doing my own pcb and wondered what type of cap to use for the 4.7uf input cap

can i use a tantalum or non polarised electrolytic? or do i have to stomach the 63p for a metalised polyester?

cheers guys.

matt

[dsavitsk]

Originally posted by led_zeppelin
i'm building a rod p3a, doing my own pcb and wondered what type of cap to use for the 4.7uf input cap

can i use a tantalum or non polarised electrolytic? or do i have to stomach the 63p for a metalised polyester?

Depends what you want the amp to sound like. If "good" is not one of your criteria, then the tant will be just fine. Some non-polar electrolytics are okay (Muse ES series, Blackgate N series) but the rest are really dreadful. otherwise I'd do MKP at least, or at least allow room for an MKP bypass.

[FastEddy]

Yes, non-polarized electrolitic is used by manufacturers 'cause they are cheaper.

" ... Some non-polar electrolytics are okay (Muse ES series, Blackgate N series) but the rest are really dreadful ..." True enough ...

" ... I'd do MKP at least, or at least allow room for an MKP bypass. ..."

Good advise =allow room on your PCB for larger caps or MKP types.

In the case of input caps to pre-amp / op-amp, bigger is better = broader frequency range down into lower bass. Non-polarized only, voltage range in excess of +/- 35 Volts and if 4.7 uF is speced., don't be afraid of 10 uF or even bigger Electro ... MKP type will sound better in most cases.

[pinkmouse]

If you're designing your own PCB, then just leave plenty of space and add lots of extra pads, then you can experiment later.

[lineup]

Hello!


I wouldn't consider anything else but some plastic film capacitor.
Not at the level of 4.7 uF.

At least use
MKT, metalized layers polyester plastic caps
or even better
the sensible diy audio choice for Best Audio HIFI, high fidelity, parameters:
MKP, metalized layers polypropylene plastic caps


As the price and size is not much different for MKT and MKP at around values of 4.7 uF
my choice is simple and cause me no headache at all:
I go for MKP Polyprophylene .... EVERY TIME!

.... it works perfect ... at least for me
.... and for a whole bunch of them other real smart diy audio builders


PS.
If you cant find 4.7 uF film caps or don't have them at home at any time,
you can parallel 1.0 or 2.2 uF caps.
2 x 2.2 in parallel = 4.4 uF
4 x 1.0 in parallel = 4.0 uF


lineup
head of
Lineup Audio Film Caps Inc.
http://lineup.awardspace.com/

[FastEddy]

" ... If you cant find 4.7 uF film caps or don't have them at home at any time,
you can parallel 1.0 or 2.2 uF caps.
2 x 2.2 in parallel = 4.4 uF
4 x 1.0 in parallel = 4.0 uF ..."

If this paralleling is required to get the exact value ... then you will need parallel rows of holes / solder pads on your board as well.

[pilli]

I've recently put together a JLH "prototype" picking most parts that I had in my personal dump. It works pretty well indeed!

For the input caps I've tried MKP or MKT or PPS caps pulled from old computer power supplies, those big filter caps rated "X" or "Y".

Is there anything against this, in terms of "quality of sound"?
To be in those PSUs they cannot possibly be good quality caps, but they're still made of the prescribed material, aren't they?

(My next try will be some foil caps pulled from old TVs... an old Grundig all packed with WIMAs...)

(The challenge is to build the amp with less than 100 Euros, without sacrificing sound quality -- not too much at least... But this is out of subject here.)

_

[FastEddy]

" ... (The challenge is to build the amp with less than 100 Euros, without sacrificing sound quality -- not too much at least... But this is out of subject here.) ..."

For your consideration: http://aussieamplifiers.com/power_amps.htm ... I just got two of the NX-150 (assembled & tested) and the sure are nice ... but this may bust your 100 EU budget ...

( http://3dotaudio.com/ampics.html )

There are a number of "chip amps" & chip amp kits that would be within your budget, however ...

[Minion]

I recently started useing some Silver Mica Caps in audio circuits and have been getting quite good results...

They are rather large but not as large as Paper oil caps or even some Poly type caps and seem to have a Nice clear warm sound, they are just a little hard to find but I was able to get some when a local Radio shack closed down.....


Just a Thought!!!

[MikeB]

I tend to use the WIMA MKS2 4.7uf, 5mm spacing. These are very small.
Their sound ? I don't know, i don't hear them...
I have already seen them in high end amps.

Mike