Reverb pans...WTF

[Chuck H]

Makes me think of something my wifes brother says... "you don't get anything if you don't ask." Brilliant. But... He says two other things that are clearly more insidious and morally questionable. One is "Regret is a wasted emotion." and the other is "It's easier to ask for forgiveness than permission." Anyone who adheres to all three of these statements is clearly out to advance themselves at anyone's expense. He's a dentist Still, you don't get anything if you don't ask!

[Leo_Gnardo]

I just looked on the Torres site and he is selling his "special secret formula" 418P's for $5 to $8.50- or you can get a matched pair of 0.1uF caps for $28! He buys them in bags of 1000 I think so he'll probably have them around quite awhile at those prices. The only thing I really like about the big OD's is that they are great for intentional parasitics! I think that might be the reason they work really well as the tone caps in the BF/SF amps- those caps are right next to each other, chattering away in their own cosmic language. Orientation of the outer foil side is very critical for parasitics (whether you want them or don't want them.)

Special Secret Formula HA! He prints his name on them & charges x4 for them. Or more likely x8 or x10 considering he's getting the quantity discount at 1000 pcs. THERE'S your special sauce. Can't knock hum much for being a capitalist, just HAVE MERCY... Torres & Gerald Weber I regard as hucksters. But they have their "True Believers" so the nonsense goes on and on. I hear GW now has a new DVD on "how to screw up amps just like I do." I've had to fix too many amps these guys have "fixed" and also emptied their customers' pockets. And those customers don't have a good attitude by the time they get to me. I'm not exactly Mister Sunshine but their amps do leave here working right, and continue to work for a good long time. P's me off that these bozos collect the big bucks.

Anyway, amps with parasitics, I just give 'em a shot of Ivermectin and they're good to go the next day...

Joke aside I can't fathom why anyone would want INTENTIONAL parasitics. Beats the heck out of output tubes & transformers. Then again there's something for everyone I suppose.

[Leo_Gnardo]

Makes me think of something my wifes brother says... "you don't get anything if you don't ask."

Well actually you do. Neglected.

Back to tanks, come to think of it, the shorty tank I used in that Kelley WAS a 3-spring. So feel safe to try that. The long 3 spring tanks are reverb-without-end.

Local college station has Sun Ra on. I'm recognizing a theme - holy crow this is where Zappa stole "The Deathless Horsie" from, on Shut Up And Play Your Guitar. Son of a gun! Well Frank admitted he nicked lots & lots of stuff... so now I know. Hmmmmph. That's what I get for leaving the radio on.

[Leo_Gnardo]

As long as we're kickin' the (reverb) can around...

Whatever happened to the QC or Gibbs cans that were "Manufactured by beautiful girls in Milton Wis. under controlled atmosphere conditions."

Maybe that's what it takes to get reverbs right - beautiful girls & controlled atmospheres. I'm all for it!

[Raybob]

As long as we're kickin' the (reverb) can around...

Whatever happened to the QC or Gibbs cans that were "Manufactured by beautiful girls in Milton Wis. under controlled atmosphere conditions."

Maybe that's what it takes to get reverbs right - beautiful girls & controlled atmospheres. I'm all for it!

Got one. Really odd resistance readings at both ends, forgot exactly the readings...

[Chuck H]

"Manufactured by beautiful girls in Milton Wis. under controlled atmosphere conditions."

Not quite as alluring as "Rolled in the plump thighs of Cuban virgins". But it'll do.

Now I just want to play my guitar with a drippy reverb tone while smoking a cigar!?!

[bob p]

Don't forget your glass of port.

[Steve A.]

I can't fathom why anyone would want INTENTIONAL parasitics. Beats the heck out of output tubes & transformers. Then again there's something for everyone I suppose.

Parasitic capacitance is not necessarily the same as the parasitic oscillations that I assume you are referring to. I was surprised to find a Wikipedia entry for it because I thought it was just something that I made up.

Parasitic capacitance - Wikipedia, the free encyclopedia

To make a long story short when I was working on my Blues Express amp project in 1999 I would swap different coupling caps in and out at various parts of the circuit. I noticed that reinstalling a cap did not always restore the sound and response that I had been getting before. I finally figured out that it had to do with the orientation of the Orange Drop cap with regard to the outer foil lead. With the OD cap installed "forwards" (with the outer foil going to the point closer to ground) the amp sounded kinda boring and blah but when I installed it backwards it had an over-the-top aliveness that was really exciting.

If the signal transmitted through parasitic capacitance is in phase (an even number of gain stages away) you can run into oscillations from positive feedback so you need to dial it in "just right". If the signal transmitted is out of phase (an odd number of gain stages away) it will make the amp more stable.

One of the amp techs at AMPAGE suggested that I try wrapping insulated wire around the Orange Drop capacitor and experiment with connecting that wire to different points in the circuit. For lowest noise you could connect it to ground but that takes all of the fun out of it. Hooking it up to preamp tube plate can make things kinda wild.

It was my theory that Ken Fischer used parasitic capacitance in building his Trainwreck amps which is why the clones never captured his magic. He used perfboard and would spend a whole week fine-tuning the amp. The Kelly 1990 schematic shows 19 fixed resistors and 13 capacitors in the audio circuit- my guess is that he would move some of those components around on the perfboard until he got the response he was looking for. What the hell else would he be doing in his basement for a whole week?

I suspect that he was using a combination of negative and positive feedback parasitic capacitance to make his amps very stable and also very alive. Just my own opinions on all of this, of course... ("Don't confuse me with facts- I have already made up my mind!")

Steve Ahola

[Martin Beer]

Regarding the MOD tanks, I've got one in a Princeton Reverb clone, and the reverb compares pretty well to the silverface Twin that's the house amp in the rehearsal space my band uses sometimes. It's not a like-for-like comparison though, as the Twin has the original tank and mine is a 9AB2C1B. Mine has a little more reverb in the lows and a little less of that fluttery drip thing when played hard. It's also a little wetter (higher output?), so I tend to run the knob quite low. But this might just be describing the difference between a type 4 and a type 9, rather than between the MOD and the old tanks.
Oh, and those OC tanks manufactured by the beautiful girls - I had one in a Roland Space Echo and always though it sounded terrible, dark, murky and claustrophobic! A pity, as the echo from the Roland was fantastic...

[Diablo]

my guess is that he would move some of those components around on the perfboard until he got the response he was looking for. What the hell else would he be doing in his basement for a whole week?

I suspect that he was using a combination of negative and positive feedback parasitic capacitance to make his amps very stable and also very alive. Just my own opinions on all of this, of course... ("Don't confuse me with facts- I have already made up my mind!")

Steve Ahola

Very interesting theory, Steve. Why else would folks have trouble duplicating the results of a fairly simple circuit in his Trainwreck?

[Leo_Gnardo]

Parasitic capacitance is not necessarily the same as the parasitic oscillations that I assume you are referring to. I was surprised to find a Wikipedia entry for it because I thought it was just something that I made up.

Verrrrry interesting, and thanks for pointing this out Steve. There are some (very rare) times I've wrapped a capacitor with copper foil (and grounded the foil) but mostly to stop an oscillation presumably due to parasitic capacitance.

I doubt Ceria and others fiddle-faddle with their TW copies in order to get 'em just right. I was surprised when I got to view the insides of a Wreck in the mid 90's and it looked mighty plain & simple, more or less a Marshall MV copy, very neatly built.

[Leo_Gnardo]

Oh, and those OC tanks manufactured by the beautiful girls - I had one in a Roland Space Echo and always though it sounded terrible, dark, murky and claustrophobic! A pity, as the echo from the Roland was fantastic...

Must be the controlled atmosphere generator was inadvertently switched off in the echo factory the day that one was made. I've had to replace a couple Space Echo reverbs that were just plain broken. Accutronics short pans. The owners were happy to have any reverb at all.

ALSO from Mark Hammer, #18. <<O'Donnell's point was essentially that, as a mechanical system, reverb springs can be made to behave differently, depending on how you push them.>>

Yes, how you PUSH them is very important, hence the Dwell control on Fender's outboard reverb. Makes the choices of reverb response much more variable. On occasion I've reduced the gain on the drive end of a Fender (or other brand) built-in reverb to get some reduction in the "splash" effect. Some jazz players for instance are looking for a mellow tone and the full-on reverb drive doesn't suit them. Just have to clip the bypass cap on the 12AT7 drive tube. If that's not enough, reduce the cap that sends signal to the 'AT from 500 pF to 250 or 220 and they're happy as could be. (I've offered to put a Dwell control in, but nobody's gone for it yet.)

[Steve A.]

Very interesting theory, Steve. Why else would folks have trouble duplicating the results of a fairly simple circuit in his Trainwreck?

Some people thought it might have been the transformers that Ken was using but then an amplifier company which shall remain nameless (cough-two rock!- cough) reportedly called up Ken's supplier and ordered 25 sets of transformers to be shipped to their shop in Northern California. Funny thing is that they then made a limited run of 25 Trainwreck clones which of course were not as good as the originals.

There are some (very rare) times I've wrapped a capacitor with copper foil (and grounded the foil) but mostly to stop an oscillation presumably due to parasitic capacitance.

One thing that I like about the 418P Orange Drop caps is that you can figure out which lead is connected to the outer foil by just looking at it. No need to do any fancy testing. Other than that there are plenty of other capacitors that work just as well as the OD's if not better. It would be interesting to experiment with a classic Fender BF tone stack using OD caps and reversing the leads, checking out all 4 possible combinations.

Steve

[Leo_Gnardo]

Some people thought it might have been the transformers that Ken was using but then an amplifier company which shall remain nameless (cough-two rock!- cough) reportedly called up Ken's supplier and ordered 25 sets of transformers to be shipped to their shop in Northern California. Funny thing is that they then made a limited run of 25 Trainwreck clones which of course were not as good as the originals.

I've heard that Ken used several different transformers including some pried off of old Dynaco MkIII hi fi amps. (Considering Sunn used the same transformers - good choice!) Just goes to show ya... How many violins have been made that are supposedly copies of Stadivarius, Amati, Guarneri, and don't measure up. Some of them just have the name of the master builder pasted inside, but sound like the cigar boxes they are. The hand of the "master" is what makes the difference. Plus aging for 300 years.

FWIW I got to work on a prototype Two-Rock a couple years ago, not a Wreck copy. Had Mercury iron. Sounded fantastic no matter where you turned the knobs. When I find amps - everyday ones - with replacement Mercury iron, the OT's always sound way too bright - nails on the chalkboard. And dead PT's. Somehow I'm not impressed with Mercury - add them to the huckster list. I suppose if you're building prestige amps and ordering a hundred transformers at a time they might build something good for you.

[Mark Hammer]

I had a lengthy chat with Bill "Klon" Finnegan about Ken once. Bill and Ken had worked together briefly. The impression conveyed, whether intentionally or not (and this is my recollection of a phone call 5 years ago), was that Ken was "difficult" to work with, and very very picky. That tends to point to the outcomes being the product of a lot of trial and error, and empirical component-swapping, as opposed to theory-driven design and ordering magic parts from unspecified suppliers. Ultimately, it's a bit like putting a hockey line together: some combinations of components fill up the time and kill penalties, and some score nearly every damn time they're on the ice. A good coach knows how to put a line together.