D'lite 44 330 pf's

[flcmcya]

I am shifting my stock 44 towards the tweaked layout ......What brand or part number is used for v2 snubbers on the tweaked layout.....I want to make sure they are beefy enough for the voltage there.
I swapped to a 360 ohm choke as well....will it matter if i use 500R/5 watt for the screens as opposed to the 470R listed on the diagragm...I am guessing not but trying to sqeeze out the best tone.

Tanks

Randall

[Structo]

The 1kv ceramics are fine there.
Not that great of voltage there.
They are tiny, it's a squeeze to put much bigger ceramics there.

I just changed mine to 330pf, subtle but nice.

IF you are running 6L6 power tubes, 470-500 ohm screens are fine.

The grids can be 3K3 to 5K1.

[flcmcya]

Thanks Structo,

Ones I have say 30 lv on them so I am guessing they might not cut it voltage wise....have to put in an order...
Watched your posts as you traveled down this path so I am just trying to speed up the process a little....thanks again.

Randall

[j-po]

For the very smoothest sound you should add an electrolytic cap right onto both screens after each resistor. I guess something like 10 to 22µ should do... This takes out harshness when overdriving the output tubes to saturation. The value of the resistor does not matter quite so much anymore, of course higher resistance still increases sag.

[Structo]

Can you clarify this?
I have never heard of doing that.

[talbany]

For the very smoothest sound you should add an electrolytic cap right onto both screens after each resistor. I guess something like 10 to 22µ should do... This takes out harshness when overdriving the output tubes to saturation. The value of the resistor does not matter quite so much anymore, of course higher resistance still increases sag.

The Idea is to place a 20uF/500WVDC filter capacitor right on each Screen-grid,(more Filtering) the tone will be a bit tighter.. This whole mod here was developed mainly in Marshall's that had reliably issues w/34's with under filtered power supply's and were run full tilt for extended periods of time.. I don't think it really applies to a D-Lite in this case (different PS)...This is in the Tone Lounge Bla Bla!!... http://www.tone-lizard.com/Marshall_Myths.htm


Tony

[Funkalicousgroove]

I fail to see how that would help, isn't the issue when the plate voltage goes below the screen voltage during the duty cycle and the screen becomes the conductor? How does filtering fix that? I can see dropping the screen voltage fixing that, but I jus't can't fathom better regulated voltage fixing that, especially when EL34's draw screen current at idle.

Maybe it gets rid of some of the ghost notes around the key of B?

[talbany]

The info on the Tone lounge is to me suspect anyway and don't buy to much into it personally.. I think what they are talking about is also adding a 5k (which makes sense) screen resistor with the added cap helps to stabilize the voltage drop across the resistor and may help speed up the recovery time on the screen supply.. I couldn't begin to guess how this would effect tone if at all .. Very early on I experimented around with an 0C3 regulator tube like Hammond does in some Leslies on there screen supply's and this does effect tone to a certain degree and definitely changes the breakup quality.. The 0c3 can only be used on 600v (in my prototypes) or more plate supply amps. It will give you a soft chime on the top.. ...for the "same" screen grid current (Is), the screen grid voltage (Vs) will be "reduced" (due to voltage drop across the screen resistor) TWICE as much. ie:

1mA thru 470-ohm = 0.47 V "drop"
1mA thru 1K-ohm = 1.00V "drop"

10mA thru 470-ohm = 4.7 V "drop"
10mA thru 1K-ohm = 10.0 V "drop"

...and, since Vs controls plate current FAR greater than Vp does, it will have both a greater and faster affect on tube compression and response.1k usually plenty for EL-34 run as a Tetrode like Marshall Dumble...most do it here..

--------------------------------------------------------------------------------


Tony

[j-po]

Believe me, there is harsh non-harmonic distortion, when all of a sudden the screen starts to conduct resulting in a sudden drop in screen voltage. The cap softens/eliminates the drop. With the cap the amp sounds almost like there is no screen resistors at all, only now you don't have to sacrifice tube life for that sound.

Of course it could also be perceived as a more "sterile" sound.

[markr14850]

So then, it seems that the screens should be at AC ground, not 1k Ohm above ground. (Kind of like cathodes in a way.) If this is the case, I'd expect that strapping the cap across the screen resistor should have the same effect - and allow the use of a lower voltage cap.

The next question is, at what frequencies does this matter, and how do we calculate the proper cap value needed?

[j-po]

Cap across the resistor is what I've been thinking also for some while but have not gotten round to testing that configuration yet. All I know is no screen resistor at all risks the amp oscillating and ground is a bit lower impedance than the screen B node which makes me think it is better to have them to ground.

Supply caps are pretty weak at killing diode switching noise, maybe its the same with oscillations? Then again, the electrolytic cap across the resistor is not a very easy route for a high freq oscillation either...