Output tube snubber kits, any experience?

[Justin Thomas]

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.

But Chuck, don't your amps do thrash metal? I mean, never seen an AC 30 do THAT...

Justin

[galaxiex]

Thanks for the great reply's!

Just in case anyone missed it, here's the Guitar player article.

[Chuck H]

But Chuck, don't your amps do thrash metal? I mean, never seen an AC 30 do THAT...

Justin

Maybe not "thrash". You really ARE better off with an uber drive preamp, then EQ and then a relatively clean power amp. That's the map to Wankerville. But my stuff isn't "smooth" like a *umble type sound either. More like if an older Boogie and classic Marshall had a (clearly illegitimate) child and you baked it in an oven set to clown shit crazy.

[Justin Thomas]

Oh, a Sovtek! (I still would rather have that Mig-100U than the '78 JMP 100W MV that had the JCM-800 front end)

Clown-Shit-Crazy...

Justin

[Mick Bailey]

If I had an amp for repair where someone had fitted components as per the instructions I'd want to cut it all out and build it up on tag strip. It looks like the mess you'd hang together just to see how it works before committing it to a proper build. Other than that, I'd only consider any kind of output filter if the amp actually needed it or if I was just curious to hear what something sounded like.

The guitar world has plenty of products to fix things that aren't necessarily wrong in the first place. I went on a business seminar where one of the topics was "People are more willing to spend money on improving something they already have rather than buy new". The speaker went on to illustrate creating a perceived dissatisfaction with one aspect of a product, whilst promoting at the same time all the positive aspects. Then the closer was to sell a product or service that 'fixed' the problem.

[nickb]

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.

I really don't think you would be seeing failures from high pulse current i = C. dv/dt as the 715P datasheet specifically mentions suitability for such applications orange-drop-datasheet.pdf.

I suggest that excessive voltage would be the more likely culprit especially if you consider the energy comping back from the speaker. Those kV rated caps seem like the smart choice for that reason.

BTW, those 8.2meg resistors are just a waste of space and money.

[Chuck H]

BTW, those 8.2meg resistors are just a waste of space and money.

I suspected the same due to the high value. But then I considered that maybe they are effectively balancing voltage at the very high frequencies being considered. But I don't know because that's out of my depth.

I did turn a 600V 715P into a dead short in this application. I had only considered the measured HV and not peak voltages on spikes. Looking into it I found that some Dr. Z amps were also failing their shunt filters. I took what I thought to be practical measures to avoid that problem in the future.

[Malcolm Irving]

…
BTW, those 8.2meg resistors are just a waste of space and money. …

Maybe they are there for civil engineering purposes - to help keep the thing up (in lieu of a proper tag-board).

[J M Fahey]

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

Steve A.

Probably .
You donīt *really* need "protection" if you donīt visit the bad girls anyway

Meaning in technical terms: if rise time of signal driving power tubes is *squashed* (what the Cut control does, and itīs always there, even if set to nominal 0 ) then they wonīt be excited into driving OT and speaker inductive impedance hard and fast, which causes ringing.

So *maybe* AC30 does have a (sort of) conjunctive filter after all

[SoulFetish]

Npt used by any classic amp, but some Forumites often have the urge to "contribute something" and post these ideas,

I'm the worst when it comes to this. But luckily Nickb is usually there to tell me to pull my head out of ass.
But when you hear him say it, you'd think he's just respectfully offering some technical reasons why my idea may not be the best approach.

as well as cascode stages (never ever used in Guitar amps)

Word on the street is, that you're one of go to cats for MusicMan amps in this joint. Would you consider that cathode drive circuit a cascode?

[SoulFetish]

You donīt *really* need "protection" if you donīt visit the bad girls anyway

Hey! If it weren't for bad girls, there'd be only good girls.

[Chuck H]

Hey! If it weren't for bad girls, there'd be only good girls.

I'll be the first to admit that I've danced with a few "bad girls". On three of a dozen designs of mine I've had to mitigate grid drive and balance screen current under tested drive conditions to find the "safe zone" and THEN take additional measures to tame potential problems under "extreme playing conditions" The "magic" of some of the old designs was how they could dance to that song without exploding... Often. So maybe those guys that we say "Never expected those amps to be cranked" were actually paying attention after all.?. It's occurred to me more than once. They were real deal engineers after all and this technology we consider old was all they were paying attention to! It would probably stun the best of us, what we DON'T know or have failed to account for.

[J M Fahey]

..... MusicMan amps in this joint. Would you consider that cathode drive circuit a cascode?

Technically yes , although thatīs not the main point making it such a breakthrough.
The real trick there lies in making a powerful Class AB2 amplifier, "hidden in plain sight".
They can smash those grids with some 20mA on demand, any day of the week.
Grids can get as much as as 20 or 25V *positive* on them.

Al this goes well beyond any classical Cascode design, which usually delves only in relatively tame Class A1 .
So yes, the Music Man power stage is a Cascode.

But I was talking about Preamps, voltage gain stages.

No Guitar amp I know of used them, my comment/rant went to lots of DIY designs using them, most using Fets after Jack Orman got undeserved appraisal after he published as his own a Fet Cascode straight out of Siliconix (or similar oldtimer disappeared Semiconductor manufacturer) datasheet or App note.

It was published as AMZ Minibooster and caught like wildfire.

Soon after, everybody and his Brother started using it as a gain stage, thinking it equals a standard tube gain stage , which it does not, and then looping the loop a few designers started porting it back to the Tube World.

Just one example of the today common Cascode application and what they claim:

[Steve A.]

Probably .
You donīt *really* need "protection" if you donīt visit the bad girls anyway

Meaning in technical terms: if rise time of signal driving power tubes is *squashed* (what the Cut control does, and itīs always there, even if set to nominal 0 ) then they wonīt be excited into driving OT and speaker inductive impedance hard and fast, which causes ringing.

So *maybe* AC30 does have a (sort of) conjunctive filter after all

FWIW I like to wire up Cut controls on pots with a rotary on/off switch so I can remove them from the circuit completely if desired. I like being able to fine tune the power amp section to accommodate the frequency response of your speakers. (Right now my favorite "go to" speaker is the WGS ET65 which can be a bit bright. It is their version of the Celestion 12-65 at half the price. BTW many of the WGS speakers are now sold by GC/MF with free shipping when you meet their minimum- one of my big complaints about ordering from WGS was their shipping charges.)

Steve A.

[J M Fahey]

I guess WGS has to ship that individual speaker from their warehouse to your home, obviously using Mail or some commercial carrier, and pay full price end to end, while since GC has branches all over the place and has to supply them anyway, using their own distribution system to a nearby shop (95% of the trip) and then "a little more" to your home, way lower cost which can be absorbed even inside a narrow profit margin.
OR, being a high volume shipper, they have an incredibly good deal with standard mail/freight carriers.