Black Gates

[speakerman1]

I get mine from this guy.

http://www.ebay.com/itm/BLACK-GATE-FK-s ... 4ab5151e14

http://www.ebay.com/itm/Two-black-gate- ... 3f187b6892

I'm looking. I have 2 50 volts sitting here.

 

[Gepetto]

Hopefully not at 68 bucks Larry...

 

[mlucitt]

What are you looking for, maybe I have them?

 

[laatsch55]

WHAT??????????????????? I know you offered before, but that was before the 470uf at C6 revelation.

 

[speakerman1]

They weren't that high when I stsrted buying. I could find others just not the 470s. I went to all but one place I know.

Larry

 

[speakerman1]

I couldn't find the 50 volts I have setting here. I bought these along time ago.

Larry

 

[laatsch55]

You a lucky mofo!! Found em diggin through your stuff??

 

[speakerman1]

Yes cleaning up the sound room.

Larry

 

[speakerman1]

I didn't pay over 18.00 for any Black Gates I bought.

Larry

 

[mlucitt]

I have (4) 33uF 160V, (6) 100uF 100V, and (2) 470uF 50V. I buy em when I see em for reasonable prices.

 

[laatsch55]

Have you installed the 470's in your 700 and these are surplus to your needs at the moment??

 

[mlucitt]

Yes, the Black Gate 470uF caps are installed and yes, I have some left over. I would like to say the Black Gates made a huge sound improvement or even a barely perceptible sound improvement; but they don't. They look cool (after you unplug the amp, slide it out of the walnut enclosure, unscrew the five sheet metal screws, and remove the top cover, but that's really about it.

 

[Gepetto]

The original Muse are great caps, probably better than the Black Gates. I will be experimenting with changing C20L/R to a 1uF or 1.5uF polyester film to determine if there is any difference in the sound. I doubt it will but will be attempting regardless on one of my next tweaks. Right now C20 is there to cancel the ESR of C6 at high frequencies (~58Khz). Making it 1uF will move it into the audible frequencies (580 Hz)

 

[laatsch55]

So now that we can hear it , it won't be there?? ESR that is.

 

[mlucitt]

I am with Joe, tweaking is good. Joe what about more of a compromise from .01 to 1, such as .1? Would that have the same effect or reducing the on ESR on C6 but put it into the middle of the audible band? Won't a 1uF polyester cap be quite large?

 

[Gepetto]

Any value of C20 will work Mark. 0.1uF will put its contribution at 5.8KHz

The 1 or 1.5uF 50V or 63V fits in the same package that the current 0.01uF does, just a little thicker and there is plenty of room on the board for this. I will get you the part numbers.

 

[Gepetto]

Wima 1uF 63V 5% = 505-MKS21.0/63/5

They are $1.05 each and in stock at Mouser. After I experiment with it, I will be switching the kit over to use this if I like the results. Would be interested in your opinions on this.

 

[Gepetto]

Wima 1.5uF 50V 10% = 505-MKS21.5/50/10

They are $1.22 each and in stock at Mouser.

 

[Gepetto]

Lee
The ESR of C6 is very low for audio frequencies. C20 is there to help the stability of the amp by canceling any ESR increase at higher supersonic frequencies due to the characteristics of all aluminum caps and to counteract any increase in ESR of the C6 cap as it ages and degrades.

The original design did not have this but should have. C6 is a critical part of the feedback loop at both low and high frequencies.

 

[laatsch55]

Thank You, that helps.