Tweedle Dee weak output

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ChopSauce
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Re: Tweedle Dee weak output

Post by ChopSauce »

I was talking about HAD's design, NB. I doubt he relied on chance and that it's bad luck the amp is running so hot.
philbard wrote: Sun Aug 29, 2021 3:42 pm
ChopSauce wrote: Sun Aug 29, 2021 2:57 pm
bepone wrote: Sun Aug 29, 2021 1:49 pm ok with this voltage you are on 100-110% ...
So am I - roughly. Isn't that a wanted feature?
My amp does sound good. It also gets pretty hot, but Fred also mentioned that his does too. Yours?
My amp still does not sound good... :?
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philbard
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Re: Tweedle Dee weak output

Post by philbard »

bepone wrote: Sun Aug 29, 2021 1:49 pm means, over the max dissipation of the 6V6.. if we assume g2 current is cca 4-5mA, then anode current is around 37mA, Padiss =13.5-14W, still is over normal biasing range of 65-70% of max dissipation /6V6 has anode dissipation od 12W, JJ claims 14W

tonewise you are close/or you are in/ class A so your amp dimmed will not go in farting blocking distortion, or will but effect will be reduced, which is good, but from dissipation aspect , 6V6 is working on 110%, and their life will be shortened due to excessive heat.

current can be dropped in two ways, reducing voltage on g2 grid , Vg2 , inserting resistor of 500-1000ohms 5W in Ub+ line going to g2,
or incresing cathode resistor for cca 30-50 Ohms doesnt matter the value, just to choke little bit anode current.
So after trying 300 ohms as a bias resistor, which made very little difference in the dissipation (2%), I swapped out the GZ34 for a 5Y3. This lowered all the power section voltages but it got the plate dissipation down to 92%. Amp is less powerful but only by a little, and the tone seems to be the same as far as I can tell. I suppose this is a comfortable combination and supposedly I'll get more life from the 6V6's. Now to spend some time playing it!

Cheers,
Phil
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bepone
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Re: Tweedle Dee weak output

Post by bepone »

great, yes, 5Y3 have bigger voltage drop..GZ34 are not dropping too much, also with 5Y3 and hard strumming you'll get more compression
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