Flash bulb power section

[EtherealWidow]

Lets talk capacitors! Not going to name names of manufacturers, but there's a particular amp company from Petaluma, California who has some amp models with a power section that is said to behave like a flash bulb in that it stores energy and releases it all at once to emphasize the transient peaks. This is especially useful for players like me who need to get a little dynamics back after saturating the crap out of their signal. Anyone have any ideas of how to do a circuit like this?

[VacuumVoodoo]

Haha! Don't say they also patented this, or tried to. That topping-off thing was developed in late 1980s IIRC by one of the japanese companies, Panasonic, Sony or perhaps Yamaha. They had a pretty descriptive name for it which I just don't remember. In principle they piggybacked a hefty class B amp on a smaller class A amp. There was sort of a predictive circuit looking at the slew rates of incoming signal and if it exceeded certain limit it fed that signal into the class B power section. Something like that or along those lines. It's been at least 25 years since I looked at this.
It works for reproduction of recordings of the more vintage type with intact dynamics. I don't think it will work with todays compressed to death material. Might not even work in live performance situation if all you play is heavily overdriven with not even a fraction of a second of as little as 3db dip in volume.....
Anyway, I'd like to check this out. Anything that might bring back some dynamics back is welcome.

[EtherealWidow]

Well of course they patented it. I thought it might have been done with capacitors done up late in some sort of weird arrangement, though. Weird. Well, I own one of the amps that uses that type of power section and it really does sound cool. Still a lot of dynamics on with a lot of preamp gain and the master dimed, although I use a couple of 12AU7's in the preamp to reduce the preamp compression. Any schematics that would do this type of thing? Would Merlin explain it in his power amp design book?

[VacuumVoodoo]

Isn't your amp called "dyna...something"?

[EtherealWidow]

Yes it is. According to marketing hype I get 30 watts from 2 EL84's!

[LeftyStrat]

Interesting. I experimented a bit with running an expander and compressor in parallel. Theoretically, in series they would cancel each other out, but in parallel the expander is only heard in the attack phase, and the compressor only in the sustain phase.

I never got around to trying this, but I thought about using an envelope follower to pan between the two based on each sides output level.

My goal was to get the sustain from heavy compression without the squished attack.

[EtherealWidow]

Are you talking in a DAW? I don't like expanders too much. In order to get something like that effect I just squish the crap out of the signal and use a really long attack time. Works good for some applications. As far as the guitar thing goes, I'd love to build something like the power section in the amp I have. It's a really cool sounding circuit.

[Reeltarded]

Downward compansion. It is a thing.

[LeftyStrat]

Nope, I'm talking analog fx in a stomp pedal. It's meant to overcome LED/LDR combos.

[EtherealWidow]

Reel: Downward compansion? How is that different from compression?

Lefty: Never been able to try it with pedals. Tried the long attack time thing with a CMATMODS Deluxe Signa Comp. Sounds really scratchy. :/

The beauty of the power section design is that it does it as one of the very last things after all the squishing. What do I look up to find a schematic like that?

When I google up "downward compansion", I get yoga results.....

[Reeltarded]

Analog pilot sets use downward compansion. It expands the signal with a broad eq cut up and down then compresses the pants off that signal.

DBX is an end-user version you would be familiar with. It's fuuuushhhiiishy.

http://encyclopedia2.thefreedictionary.com/Compansion

[LeftyStrat]

So many techniques with compression/expansion. You can split the signal and compress the highs. But I will defer to Miles. I want to drink his brain, but it hasn't happened yet.

[EtherealWidow]

But nobody has some schematics of these great ideas for a dynamic power section?

[Colossal]

But nobody has some schematics of these great ideas for a dynamic power section?

If you don't have these already, see attached. You probably know that Petaluma is known to publish schematics with errors just to thwart "patent infringers" and the academically curious, so take everything with a grain of salt.

[EtherealWidow]

Thank you. To my untrained eye, those schematics look suspiciously boring...