Finished capacitance multiplier

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#663
The Fet version has been around in the F series First Watt and Aleph series amplifiers for some time now and works like a charm - the Rod Elliot version (as per Post 661 above) is easier to build than this 'finished' versions and still obtains much of the benefits -
Nearly all types are beneficial in any power supply and, IMO, are the 'best bang for the buck' in supply filtering, especially when low noise diodes and secondary winding 'snubbing' (simple Haggerman types) are used too

Shamron, just put it together and try it out - first hand experience with these things is the best teacher - you can analyse there things to a standstill - don't be afraid to generate a bit of heat in the pass transistor and can just clip on a heatsink if necessary
 
#666
Yeah Bare, always there's 'trade-offs', but if using the C-Mx as a filter, not a cap substitute, and care with capacitor choices, many benefits can be achieved for low power consumption

For amps like a BA-1, the actual capacitor type and Fet/Transistor directly effect the sound (especially the one between the C-Mx and the amplifier) - different caps have a different 'sound' under load .....
 
#668
IMO, 'not necessarily so'
The size of the capacitor produces it's own compromises and if you regard the C-multiplier as a filter, the energy required by the amplifier is mainly supplied from this 'last cap' and so, current transients, joule delivery, dynamic impedance, latency, etc are quite different for any of the 10mF (10,000uF) caps mentioned above.

Unfortunately, different types of classA amplifiers will have produce a different sound with different types of supply capacitors - no news here, I think.

Possibly, an example is a better description here -

On my standard F5 amp (that has a similar sensitivity to the power supply as the BA-1), when it's used to drive the FR drivers only from 150Hz upwards, the power caps (the 'last caps, nearest the amp) are fitted with the 4,000uF DNMs SlitFoils (by BHCs) after the C-Multiplier (no onboard bypass caps, by the way) as they're one of the best 'midrange' caps available for this sort of setup, IMO naturally - I think only 10,000uF sizes available in SlitFoils, T Networks these days
However, a friend of mine prefers a much 'softer' sound using the same type of amp for driving his Lowthers and prefers the 6,800uF Jensen 4 pole electros in the same position (forget the cost!).
Yet another guy uses the same sort of amp on his 3 way speakers JBL M series) and has 2 x 6,800uF Nichicon SuperThru caps fitted after the same C-multiplier

So, 3 different requirements have 3 rather different types of power caps (last caps, etc ) and size isn't the determining factor but the caps particular qualities - similar differences appear in 'less boutique' caps too - Elna, Nichicon, Panasonic, United Chem, EDC, etc

Hope this is of some use ...
 
#678
Yes, I did just that and used Miles' CMxs for an F5 running about 1A7 and rails about +/-20 volts to amp - initially had some concerns about the + and - rails charging at slightly different rates so added a dc protect and delay relay - also acts as mute - used same amp channel heatsinks -- excellent result
Started with Nichicon SuperThru 6800uF on o/p but reduced this to 1000uF BHC for better moids/speed as the amp is used for >150Hz - couldn't find any 1100uF SlitFoils to try - 470uF Nichi Bipolars pretty good also

I later tried PMI Simplified, joachims, and others and got similar good results so just used the 'less complicated' ones since

CMxs are the 'best bang-for-the-buck' anywhere, IMO.
 
#679
jameshillj said:
Yes, I did just that and used Miles' CMxs for an F5 running about 1A7 and rails about +/-20 volts to amp - initially had some concerns about the + and - rails charging at slightly different rates so added a dc protect and delay relay - also acts as mute - used same amp channel heatsinks -- excellent result
Started with Nichicon SuperThru 6800uF on o/p but reduced this to 1000uF BHC for better moids/speed as the amp is used for >150Hz - couldn't find any 1100uF SlitFoils to try - 470uF Nichi Bipolars pretty good also

I later tried PMI Simplified, joachims, and others and got similar good results so just used the 'less complicated' ones since

CMxs are the 'best bang-for-the-buck' anywhere, IMO.
Click to expand...

Thanks for the inputs. I'll try the PMI I have but will also look into the CMx. Any PCBs available anywhere?

Thanks
Do
 
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