MKP film for tube amp power supply

[bud]

Been thinking of yanking out the electrolytics and replacing with MKP medium power film or DC link rated for a rather big power supply in a Mesa Baron.  No doubt there would be an improvement.

Has anyone done this with the newer non-audiophile names?  I see on Mouser/Allied/Newark a bigger selection every week and prices dropping.  Names like AVX, CDE, WIMA, Kemit, all showing new film product.  If any one has some comments on one brand over the other for 'sound quality', I love to hear it.


Was looking at WIMA 890@700 or CDE 860@900 for the main B+ (at about $100 each) and some smaller values for the screen and preamp tubes.  Yes, that is a lot of Uf.  Currently the amp has 6 Chemicon 4700@100VDC in series (with resistor bleeder/equalizers), (which is about mid 800uf) and pushing 15years old.  Believe it or not, the cost is about 1/2 what the film would be to replace these.

For the smaller values I just found this today:
http://www.mouser.com/ds/2/427/mkp1848sdclink-46399.pdf
Not sure how well a non 'rolled round' cap would be for audio, with plates perhaps vibrating on the long side of the winding even though these say 'potted'.

I know what good quality films can do in coupling, but haven't used these in a power supply before.

 

[earwaxxer]

Wow - like you said - thats a lot of uf's! I would try bypassing some good electrolytics with films first. I think that would give you an idea. I would guess that it wouldnt make much difference. The place you want to invest in good films is in your speaker crossovers (if you have a crossover that is). Thats where I would be tempted to spend $500 on caps.

 

[Paul Birkeland]

I've had some AVX film caps explode on me when being run at half their rated voltage, so I stopped buying them.

The big CDE film caps seem nice, I have a fair number of them at the moment, but the project they are built into isn't quite finished.

 

[johnsonad]

Been thinking of yanking out the electrolytics and replacing with MKP medium power film or DC link rated for a rather big power supply in a Mesa Baron.  No doubt there would be an improvement.

Has anyone done this with the newer non-audiophile names?  I see on Mouser/Allied/Newark a bigger selection every week and prices dropping.  Names like AVX, CDE, WIMA, Kemit, all showing new film product.  If any one has some comments on one brand over the other for 'sound quality', I love to hear it.


Was looking at WIMA 890@700 or CDE 860@900 for the main B+ (at about $100 each) and some smaller values for the screen and preamp tubes.  Yes, that is a lot of Uf.  Currently the amp has 6 Chemicon 4700@100VDC in series (with resistor bleeder/equalizers), (which is about mid 800uf) and pushing 15years old.  Believe it or not, the cost is about 1/2 what the film would be to replace these.

For the smaller values I just found this today:
http://www.mouser.com/ds/2/427/mkp1848sdclink-46399.pdf
Not sure how well a non 'rolled round' cap would be for audio, with plates perhaps vibrating on the long side of the winding even though these say 'potted'.

I know what good quality films can do in coupling, but haven't used these in a power supply before.

I'm considering a Paramount build using the 800v WIMA's in the PS.  A custom chassis of course but I would use the same values and replace the 270 Ohm resistor with a choke.  What build where you considering using them in?

 

[bud]

Hi Aaron,

thanks for the reply, I have been swamped with personal issues and just couldn't get back here.  I am rebuilding A Mesa Baron Amp.  I talked to the MESA tech department guy and he said I needed 800uf to replace the string of caps in there now, plus two 47uf one for the screen and one preamp tubes.  The caps would all be outboard, there is no room for such caps under the hood.  This is a wonderful amp but it does run out of steam in pentode, split triode/pentode is good, triode all is wonderful.  I can't help but think the 'run out of steam' is this power supply.  He thought it was a great idea.  I thought about trying a parafeed type of set up instead, but that doesn't solve the power supply not being able to stomp on the gas when it needs to.  I can post a schematic if anyone wants to see it.  The main supply not is CDE and ATOM, not junk for sure, but just short of the headroom this amp asks for playing rock or rambunksuch sysphonic music.

The bypassing idea on the power supply caps is a nice idea but doesn't add any reserve power.  I bypass most power supplies as noted, but that is not my problem right now.  Thanks for the thought earwax.  Not spending 180 bucks on a total hot-rod power supply is not great money.  I already have near top line in the speakers, but that is not the problem either.
bud

 

[Paul Joppa]

Just a thought here ... I'm no pentode expert, but they seem to respond well to screen voltage regulation so I expect that bigger capacitance on the screen supply will have a big effect. Keep the forum informed of what you try and what you hear!

 

[4krow]

MKP=what?

 

[Doc B]

metallized polypropylene

 

[4krow]

Thanks

 

[bud]

Just a thought here ... I'm no pentode expert, but they seem to respond well to screen voltage regulation so I expect that bigger capacitance on the screen supply will have a big effect. Keep the forum informed of what you try and what you hear!

There is a choke before the screen cap filter. That filter is two 47uf in series making a wopping 25uf with 110 ohm bleeders.