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Capacitor upgrades and anniversary mod suggestions (Read 2658 times)

jbohlscheid

Verified Member

Posts: 23

Capacitor upgrades and anniversary mod suggestions
12/21/20 at 17:43:54

I am planning out my upgrade experiments for my next Zkit#1 builds. I have a board that is now up and running and set up for modular experimentation for learning tube and amplifier design.
There are main two areas for passive components:
1. The current capacitors
2. The anniversary bypass caps and resistors

For #1 I have seen replacement of the two 0.1 uF 400V coupling capacitors with copper Jupiter and Mundorf products and the 3.3 uF (signal?) capacitors with Mundorf products. Are these the two places where the is the most bang for the buck? Would the 33 uF and 20 uF power supply capacitors be a significant upgrade?

I read Steve's description of the anniversary upgrades on the production items, and I'm not sure how these relate to the Zkit#1.

With respect to #2 are there suggested makes and models for the various bypass capacitors and resistors?

Thanks for your thoughts. JCB

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bobc

Senior Member

Posts: 67

Re: Capacitor upgrades and anniversary mod suggestions
Reply #1 - 01/03/21 at 14:48:58

Much to unpack in your question. I am not an expert, but I have built a few kits and clones.

1. You can get a quieter B+ if you upgrade the smoothing/ filter capacitors to a higher value when using diode rectifiers. 47uf is a good place to start. A few posts in this area on on the site.

2. In so far as the anniversary mods to the KIT are concerned, I have done these mods to a kit I previously built, I used high quality coupling capacitor in main signal path (copper whatever magic) and lower quality, but same brand/value for bypass of all the caps. You may want to play with the bypass caps on PS filter if you change values. Keep leads short on bypass as all that wire can also create problems. The goal as I understand is to speed up the response of the PS. I can say they didn't hurt!

As to how any of the anniversary mods to the production equipment relate to the ZKIT recommendations, I imagine these are informed by some of these developments, but another matter and approach given the use of glow tubes etc. You should read the posts on the anniversary mods for the UFO etc... loads of information that might inform your choices. The schematics for all these changes are rightfully proprietary, although there is an amazing level of detail in the posts if you read carefully. The newer models even omit the 10K/3.3uf network to feed input tube. The .1uf coupling caps are directly in the signal path so that would also be an area to upgrade eg play with different types/brands.

You can swap around components and experiment. I think if I HAD to answer, the upgrade filter/smoothing from 33uf to 47uf to get a quieter b+ is most bang for buck, followed by great coupling caps. Just my experience. Hope this helps!

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jbohlscheid

Verified Member

Posts: 23

Re: Capacitor upgrades and anniversary mod suggestions
Reply #2 - 01/05/21 at 18:46:48

Solder Bob,
Thanks for the information and suggestions. I'm new to electronics and audio building so everything helps, and I fully understand the "go with what is good for you" ethos.

1. You can get a quieter B+ if you upgrade the smoothing/ filter capacitors to a higher value when using diode rectifiers. 47uf is a good place to start. A few posts in this area on on the site. I assume this refers to the two 33uF 450v capacitors associated with the power supply. I also assume one would stay with at least 450V if replacing with a 47uF capacitor.

2. In so far as the anniversary mods to the KIT are concerned, I have done these mods to a kit I previously built, I used high quality coupling capacitor in main signal path (copper whatever magic) and lower quality, but same brand/value for bypass of all the caps. You may want to play with the bypass caps on PS filter if you change values. Keep leads short on bypass as all that wire can also create problems. The goal as I understand is to speed up the response of the PS. I can say they didn't hurt! Excellent suggestion. Added to the to-do list.

As to how any of the anniversary mods to the production equipment relate to the ZKIT recommendations, I imagine these are informed by some of these developments, but another matter and approach given the use of glow tubes etc. You should read the posts on the anniversary mods for the UFO etc... loads of information that might inform your choices. The schematics for all these changes are rightfully proprietary Of course, this is someone's hard work and should be respected, although there is an amazing level of detail in the posts if you read carefully. The newer models even omit the 10K/3.3uf network to feed input tube. There is an interesting idea The .1uf coupling caps are directly in the signal path so that would also be an area to upgrade eg play with different types/brands.

You can swap around components and experiment. I think if I HAD to answer, the upgrade filter/smoothing from 33uf to 47uf to get a quieter b+ is most bang for buck, followed by great coupling caps. Just my experience. Hope this helps! Great stuff, Thanks, JCB

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bobc Senior Member Posts: 67	Re: Capacitor upgrades and anniversary mod suggestions Reply #3 - 01/06/21 at 14:28:28 Yes. Keep voltage ratings of capacitors. 450V. High voltages and capacitors can keep charges so be careful!
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