Two different types of plate caps in use?
Moderators: pompeiisneaks, Colossal
Two different types of plate caps in use?
Hi all,
On my Marshall JCM 2000 DSL 50, in parallel with the electrolytics on the 12AX7 plates I see they have ceramic caps of the same value. That is, the plates have both a 10uf electrolytic as well as a 10nf ceramic cap wired in. Never seen this before. What is the purpose of this?
Thanks in advance.
On my Marshall JCM 2000 DSL 50, in parallel with the electrolytics on the 12AX7 plates I see they have ceramic caps of the same value. That is, the plates have both a 10uf electrolytic as well as a 10nf ceramic cap wired in. Never seen this before. What is the purpose of this?
Thanks in advance.
Last edited by dehughes on Wed Nov 01, 2017 8:19 pm, edited 1 time in total.
Tempus edax rerum
Re: Two different types of plate caps in use?
I see a 10nF in parallel with a regular 10µF electrolytic. The small cap is used because it reacts better for fast transients so it's more efficient at filtering fast noise spikes.
Re: Two different types of plate caps in use?
Ah, sorry, thought that was "uf"...thanks.
So how is this "better", or, how does this setup express itself in tone and feel?
Tempus edax rerum
Re: Two different types of plate caps in use?
I don't think this is going to effect"Tone and Feel" as you say.... it's more about avoiding un-wanted noise artifacts, oscillations... etc. things that pop up in a high gain amp....
TT
TT
Re: Two different types of plate caps in use?
Oh cool. Thanks.
I notice such caps are not used in "classic" Marshall-type circuits. Would removing these caps make any discernible, audible difference? I ask because I'm in full-on tinker mode with my DSL 50.
Tempus edax rerum
Re: Two different types of plate caps in use?
Pull 'em out. See what you think. Put 'em back in. That should satisfy your tinker mode for a while.
Re: Two different types of plate caps in use?
OH BELIEVE ME, I want to, but the older, wiser part of me says to ask here as you guys know more and can likely save me some effort.
(However, if no replies by noon PST today, then there's a good chance I'll just pull them out anyway.)
Tempus edax rerum
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Re: Two different types of plate caps in use?
I was gonna say, my God 10 uf ciramic s must be huge and act like a Microphone all on there own!
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1 others liked this
Re: Two different types of plate caps in use?
Whenever I used a 0.1uF capacitor in parallel with the filter capacitor it was because V1 was like 35cm from the filter cap. The 0.1uF capacitor was not physically located right next to the filter capacitor as it was shown on the schematic. The 0.1uF capacitor was physically located at the V1 end of that 35cm antenna to shunt any noise it picked up to ground.
Re: Two different types of plate caps in use?
Interesting. These 10uf caps are right next to the filter caps, and maybe two inches from V1. I've ran much longer B+ leads in my handbuilt amps without issue, so I'm inclined to remove them and see whassup.Ten Over wrote: ↑Thu Nov 02, 2017 4:09 pm Whenever I used a 0.1uF capacitor in parallel with the filter capacitor it was because V1 was like 35cm from the filter cap. The 0.1uF capacitor was not physically located right next to the filter capacitor as it was shown on the schematic. The 0.1uF capacitor was physically located at the V1 end of that 35cm antenna to shunt any noise it picked up to ground.
Tempus edax rerum
Re: Two different types of plate caps in use?
Removed them...don't notice much difference either way. Leaving them out as less is more, IMHO.
Tempus edax rerum