Phono 3 with 5751 valves

[Shian7]

Here's a bargain for someone that I nearly snapped up myself, But I've got my eye on 'something else'.

This guy is a very reliable seller!

http://cgi.ebay.co.uk/2-pcs-NOS-GE-J...item20b016590c

[Ali Tait]

:d

[Shian7]

[bearded fiddler]

I did the Oscon bypass cap mod and I also put in GE 5751 valves. The sound was very good but the it didn't really come alive. But now, at last, I unleashed the full potential of my Phono 3S! I substituted 2.2 uF Mundorf silver/oil caps for the Soniqs PXX I had already replaced the standard orange drops by, and the result was amazing. It wasn't an easy job though: these caps are so big they really had to be shoehorned into the casing.

Jan

[Dik Dolan]

Hi Jan,
I too recently put a pair of the silver/oils in my non-S phono3 and agree completely, they just seem to let everything through, seem so transparent and lively. Lovely stuff=)

http://www.world-designs.co.uk/forum...0&postcount=15

[BOONDI]

Originally Posted by bearded fiddler

I did the Oscon bypass cap mod and I also put in GE 5751 valves. The sound was very good but the it didn't really come alive. But now, at last, I unleashed the full potential of my Phono 3S! I substituted 2.2 uF Mundorf silver/oil caps for the Soniqs PXX I had already replaced the standard orange drops by, and the result was amazing. It wasn't an easy job though: these caps are so big they really had to be shoehorned into the casing.

Jan

Hi Jan, all.....
Just a quick question. Why use pxx in the first place.
This position deserves the SAX or better.
I cant afford silver mundorfs so i'm going to try some ruskie caps from fleabay....

[bearded fiddler]

Hi Boondi,

Richard suggested that in this case PXX is as good or even better than SAX (see the thread Soniqs SAX caps).

Jan

[bevensee]

Originally Posted by Richard

Hi Jan,

Keep reading, familiarity is half the battle, it will all drop into place. Bruce Rozenblit is good too,
http://www.amazon.com/Beginners-Guid.../dp/1882580133

That coupling is a cap into an impedance, known as a high pass filter. It has a slope of 6dB/Octave and its "corner frequency" is expressed halfway round at -3dB point.

The bigger the cap value the lower AC f it will pass into a given impedance (AC resistance of path to ground).

In our case C1/2 0.015uF into R13/14 1M

We can use a formula or a calculator,
http://www.muzique.com/schem/filter.htm

Enter the values and see it is 10.6Hz. You can work out the others.

Play with the calc, double and halve values and you'll see the ohms and cap are equally important.

Here's the PhonoII design article covering exactly this, hope Peter doesn't mind, only part of it and a good advert for other articles on the WD archive CD from the shop so you can check those through too against the designer's text,

Sorry, but I don't get this. Can someone explain?
- R13/14 is not 1M
- I you use 0.1 uF into 1MOhm, cutoff is only 1.6 Hz

I guess my question is: If I want to get rid of the switch, and have a corner freq. of the subfilter around 20 Hz, What value should I use?
What if I want to increase the slope to 12 dB per octave, how do I do that?

[Richard]

Originally Posted by bevensee

Sorry, but I don't get this. Can someone explain?
- R13/14 is not 1M
- I you use 0.1 uF into 1MOhm, cutoff is only 1.6 Hz

I guess my question is: If I want to get rid of the switch, and have a corner freq. of the subfilter around 20 Hz, What value should I use?
What if I want to increase the slope to 12 dB per octave, how do I do that?

Hello and welcome

Yes sorry, typo now corrected thanks, read R9/10 1M.

The 20Hz filter was the middle one I think so just check with your meter which caps are connected at that switch position.

[bevensee]

Hi Richard,

Thanks for the quick reply!

Is there anything gained in swapping to a different king of capacitor in that position? If so, can you give recommendations?

Thanks,

Jesper