Output tube snubber kits, any experience?

[galaxiex]

Like the title says...

Anyone have experience with these snubber kits?

Any good/worth it?

The write-up "sounds good" or is this voodoo?

https://www.amplifiedparts.com/produ...t-2-el84-tubes

[Justin Thomas]

I would look it up in the RDH4. And that is considered a pretty dang reliable source. See what it says there, and see if it would make sense to apply it to a guitar amp.

Now I'm curious...

Justin

[pdf64]

...The write-up "sounds good" or is this voodoo?

https://www.amplifiedparts.com/produ...t-2-el84-tubes

The writer's understanding of tube guitar amp operation differs considerably to mine
Most every sentence seems to have some degree of error / nonsense.
And which SF Fender models had OT protection diodes?

But however flawed the technobabble, you may like the effect of the snubbers.

[J M Fahey]

What´s a typical EL84 PP impedance? 8k?
IOF so, .0047uF across that will attenuate 4kHz about 6 dB.
I wouldn´t call that "transparent"

Not bad from a theoretical point of view, in practice it will be either a good thing (it kills buzz) or a bad thing (it kills sparkle).

Npt used by any classic amp, but some Forumites often have the urge to "contribute something" and post these ideas, as well as cascode stages (never ever used in Guitar amps) and similar stuff.

Pick your own poison, meaning try it and post results; experiment is real cheap-

Typical of Net level information, they did not bother to post a schematic or explain operation, just mention the Word of God with zero detail or elaboration.

[Chuck H]

Well there's nothin' fancy about it except for the way it's wired (to look somehow symmetrical between the tubes?). See below.

Other than that it's just a "conjunctive filter". Some guys hate that term, but it's the one we've come to know. You could wire it with a single 6k/5W resistor and a single 2200p cap for the exact same result. But then you wouldn't have those fancy Orange Drops and that symmetrical look that makes it seem like it's "balanced The truth is that very little consideration is given to this public offering WRT function because snubber circuits like this should take OT primary impedance into account and a scope should be employed for determining circuit values. It's just a masked face on an old circuit. But...

Before you think I'm poo pooing the whole thing, I use a snubber filter on my own el84 design. Dr. Z seems to like them for el84's also and has done quite well with them. I use a 10k resistor and a 1500pf cap with an OT primary of 8k. I don't know what Dr. Z does.

[Chuck H]

Juan, it's wired with the caps in series, so it's actually .00235uF with a 6k series resistance parallel to the OT. Even still, it is NOT transparent. The more conservative snubber I use is not transparent.

EDIT: Just looking at the components again in the image. What a silly thing that is. Sort of like making a face on your plate out of your bacon and eggs for breakfast.

[pdf64]

RDH4 reference on p567 https://archive.org/stream/bitsavers.../n607/mode/2up
The seemingly pointless symmetry of the circuit may be due to it being kinda copied from the Dominator http://wem-owners.com/wp-content/upl...nator-sch1.pdf but the OT primary CT connection omitted.

[Chuck H]

Indeed! The circuit values look similar enough considering standard values. I think R.G. mentioned (more than once) that he thought snubbing to the CT was better than snubbing the whole winding.

One other thing about the "kit" that I don't like is the use of cement resistors. Their specs indicate they aren't the best choice for high voltage applications. I went with something called a "high energy" resistor that I found at Mouser. I can't remember what it was It was rated at 11W and I chose it for it's voltage rating. And OD caps aren't designed as snubbers. Punch enough holes in the film and foil construction and the cap becomes a short (ask me how I know ) I chose to use a cap designed as a snubber with a voltage rating of something like 2kV.

[mozz]

On the 18watt marshall forum, they use these "if" they have the problem of the output being fuzzy or fizzy or buzzy, however you want to describe it. It is a copy of the Watkins Dominator anyway as was said above. Solution looking for a problem?

If you ran a freq response sweep of the output (or output and driver stage), you think any fizzy or fuzzy would show up? Maybe if using a speaker instead of a dummy load?

[Chuck H]

If you ran a freq response sweep of the output (or output and driver stage), you think any fizzy or fuzzy would show up? Maybe if using a speaker instead of a dummy load?

Well the HF spike certainly shows up. The "ringing" mentioned in the write up for the kit is indeed common to 2xel84 designs. One problem with this is that with an actual speaker load the reflected impedance at these spike frequencies can be greater at the plates than the screens. So you can end up overdissipating the screens with sustained, extreme overdrive (ask me how I know ) That's the reason I use the snubber. Contrary to Zimmerman I don't recognize any "brick wall" effect from the Zeners. But then, it's not clear what circuit is being discussed or how the Zeners are implemented in his comparison. I use the Paul Ruby mod Zeners in combination with a bias clamp Zener with a self biased (cathode biased) circuit and my own criteria for tuning it. All I notice is a minimization of excessive crossover distortion. YMMV

[Jazz P Bass]

A good read: Tubes

[g1]

I've seen similar filters in some Garnet models, possibly Traynor also?

[J M Fahey]

Best known and most respected EL84 user?: VOX AC30
Do they sound good? .... you bet.
Do they use snubbers? ..... are you kidding?
Case closed.

[Chuck H]

Love it Juan. And I might take it personal if my amp wasn't designed to do things the AC30 doesn't And, to be fair, the AC30 incorporates more than one slightly goofy circuit of it's own. In principal you're spot on though. If a player can't make music of almost any genre with an AC30 then what's it going to take.

[Steve A.]

Best known and most respected EL84 user?: VOX AC30
Do they sound good? .... you bet.
Do they use snubbers? ..... are you kidding?
Case closed.

With the AC30 having a Cut control perhaps the need for a snubber circuit or conjunctive filter is reduced...?

Steve A.