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-   -   Output coupling caps in Arcam Alpha 5 CDP (http://www.diyaudio.com/forums/digital-source/59525-output-coupling-caps-arcam-alpha-5-cdp.html)

filholder 21st June 2005 11:26 PM

Output coupling caps in Arcam Alpha 5 CDP
 
I have a heavily moded Arcam Alpha 5+ CDP (diodes op amps and caps on audio and main board).

I want to replace the output coupling capsfor something better. I have got some good quailty 4.7uf 630v polypropelene caps i want to put in instead of the old nichicon nonpolar 100uf caps. Will i need to change the value of say the ouptu resistor in series with the caps to make these work or is this not an issue?

Any comment greatfull recieved.

Fil

georgehifi 22nd June 2005 11:14 AM

Fil, if the 4.7uf cap you intend to use is seeing no lower than 50k to deck then it's ok, you'll have a -3db point of .6 of a hz which is fine, but say the resistance to deck that the 4.7uf sees is 1k to deck then the -3db point will become 33hz roll off. It's cutting well into the bass, not good. Hope this helps.

Cheers George

filholder 22nd June 2005 01:15 PM

Hi George,

Thanks for the reply, by 'to-deck' i image you mean to ground. Where do i measure this, is it from the input of the cap to ground? and if i want to change the resistance i putt this on the input of the caps i image from what you said rather than the output.

Sorry if all this is obvious I am raather new to all this.

Thanks again,

Fil

georgehifi 22nd June 2005 09:22 PM

Yes to deck is slang in Australia for to earth.
Put your 4.7uf in then with yourinterconects and preamp or what ever comes next hooked up also, measure from the output of the cap to the cd players rca earth, this will tell you the combind load (resistance)cd is seeing, that is the input impeadance for the pre the interconent and whatever resistors are lurking hidden after the 4.7uf coupling cap.

Cheers George

filholder 22nd June 2005 11:07 PM

Cheers George,

Your a star, very hepful. I think i have a much better understanding now.

fil

Franz G 23rd June 2005 12:22 PM

Maybe interesting for Arcam Alpha 5 owners, maybe it is an exception:

Today, I unsoldered a TDA1541A out of an Alpha 5 board. After done that, I gently pulled on the rubber ring around the crystal:

The crystal could be pulled out of the board easily! No unsoldering needed!

Carefully inspecting the soldering points of the crystal: very little solder at the pins.

Maybe it is worth to check the crystals solderings, when opening the player!

Kind regards
Franz

filholder 23rd June 2005 01:28 PM

Cheers Franz,

However since i covered my crystal with shrink wrap a while ago I know for a fact mine is in there tight. It had to be for all the force it took for me to put the shrink wrap on.

Of course one day when funds allow it might get a new clock but i though a few layers of shrink wrap should stop it at least ringing for the time being!!.

Fil


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