| john blackburn |
For the Uno preamp shown on Decibel Dungeon what would be the effect of using an electrolitic capacitor in the CSN position?
http://myweb.tiscali.co.uk/nuukspot...nclonepre2.html
The only non polarised 22uf I can get is only rated at 50V not the 63V recomended for this design but I have a new 63V 22uf electrolitic in the bits box.
Any guidance as to which, if any would be suitable would be welcome as indeed would a bit of background info on what its function is in the circuit. I assume its the last stage of "supply filtering" but I am ready to be corrected!
Many thanks
JB |
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| Nuuk |
JB, I don't recall buying an NP cap for that position so I would guess that I used a standard lytic!
If you want to check it out with CFM, he now 'resides' on another forum .
As regards voltage rating, work out what your voltage rails will be and multiply by 1.25 to be on the safe side. :att'n: |
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| john blackburn |
If you are happy to go with the electrolitic thats more than good enough for me! The 50v option sounded a bit too close for comfort. Its better to ask a question than it is to pick bits of amp from my forehead though.
Thanks for the advice, it's because I spotted your tubular monoblocks on DD that I asked Google what a "Gainclone" was, now I'm having a go at one of my own.
JB |
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| Nuuk |
| quote: | | Thanks for the advice, it's because I spotted your tubular monoblocks on DD that I asked Google what a "Gainclone" was, now I'm having a go at one of my own. |
Another victim! :D |
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| john blackburn |
It all seemed so simple at first, buy a kit and put it together, job done. Since then I have spent countless hours reading about how to do this simple task correctly. Every answer found raises two more questions apart from the super hard equations, they raise a confused expression and a headache. Its the most complex project Ive taken on so far but its taught me loads.
All thats needed now is for it to work and all the struggle will be forgotten and its time for project 2, whatever that may be. |
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| CarlosT |
| It's a disease, man...now I'm dreaming of low voltage tube preamps for an LM3875 GC...SICK, man...SICK :D |
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| john blackburn |
| There have been times when I had thought it a mistake, I should have simply bought an amp from a shop. I could have saved time and headaches and had something that worked from the box, but wheres the fun in that? |
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| sandstorm33 |
| From the schematic it appears that a 50vdc rating is quite sufficient . If you are using the transformer voltages stated there really is no problem . Capacitors are generally liberal with their ratings and can always be counted on to operate continuously at their max. The 50 volt NP Cap should be fine . |
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| Nuuk |
| Carlos has confirmed that the CSN cap is a standard electrolytic type! :att'n: |
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| john blackburn |
Thanks for all the help and advice to one and all. I went with the 63V electrolytic this afternoon as it was here and didnt need postage paying for one capacitor.
All thats needed to do now is to convert two dead videos into a couple of usable chassis, make a pair of FR125s ported monitors by Vikash, make pvc pipe speaker stands and pluck up the courage to switch the whole shenanagins on! Using a 60W light buld in series and with one hand in my pocket obviously. |
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| Nuuk |
| quote: | | Using a 60W light buld in series and with one hand in my pocket obviously. |
And after checking DC offsets, connecting up to an old 'test' speaker first! ;) |
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| john blackburn |
After those steps also! Just one last question about the uno if I may.
What would be a suitable va rating for the transformer?
The regulator has a one amp limit so would I be right in thinking 36V x 1A = 36va? Presumabbly theres an "over spec" factor for the rating to ensure the supply remains stable under hard load.
The options I have are 50va and 80va 2x18v would that be ok, or is a higher rating advisable? |
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| Nuuk |
50VA or 80VA will be more than enough! Some folks say a bigger traffo sounds better and there may be something in that or not!
Looking at the prices from Farnell, there is only a couple of pounds difference between the 50VA and 80VA so it's your choice! ;) |
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| john blackburn |
| Oops, double posted somehow, sorry Also seem to have picked up part of another post so please ignore the last couple of entries |
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