Is PS Ripple Integral to an Amp's Tone?

[David Root]

This sounds pretty dumb I know, but I picked this attached item off the Pentode Press site. Interesting experiment with entirely unexpected result. Maybe this is old news but I had not seen it before.

Don't know if this would replicate with a SS rectifier, but....

[RWood]

My curiosity is now sufficiently piqued to spend more time than my spouse deems necessary to experiment!

[Firestorm]

I think I've mentioned this before: early Marshalls (especially Superleads) were ridiculously underfiltered and exhibit a lot of ghost notes when driven. These are sum and difference frequencies of the ripple and the note being played (and of the harmonics). When Hendrix was exploding on the scene, everyone wanted to get his sound, but players in the US were thwarted because the tracks they wanted to emulate had been recorded in the UK with 100Hz mains.

[jelle]

50 Hz doubled.

[Firestorm]

Yes, Jelle. What I meant. Jeez you guys are precise.

[The Ballzz]

All I can say is, WOW, who'd've thunk it?! Interesting read and thanks for sharing. Each new perspective simply adds to the arsenal!
Thanks Again,
Gene

[jelle]

Yes, Jelle. What I meant. Jeez you guys are precise.

[Kagliostro]

I'm not so skilled about the argoument

As far I can know the PS capacitors values are very important on the

bandwidth response of the amp and on the curve of the frequency response

so an amp filtered with an 8UF capacitor would sound different from one

filtered with a 100uF capacitor

In the Vox AC30CC2 there are 22uF capacitors on the PS filter and

additionally switchable further 22uF capacitors

the switch that performs the parallel of this capacitors is called

smoothing switch and the two position are indicated as

Vintage and Modern

So if they decided to do that, to me is an evidence that the value of

capacitors (and consequently the level of ripple) has an effective

influence on the response of the amp)

[img:4323:3072]http://i.imgur.com/L6Fi1zS.jpg[/img]

K

[Roe]

I think I've mentioned this before: early Marshalls (especially Superleads) were ridiculously underfiltered and exhibit a lot of ghost notes when driven. These are sum and difference frequencies of the ripple and the note being played (and of the harmonics). When Hendrix was exploding on the scene, everyone wanted to get his sound, but players in the US were thwarted because the tracks they wanted to emulate had been recorded in the UK with 100Hz mains.

Its only the 1967 100w amps, both superbass, superlead and super 100 amplifiers, that were ridiculously underfiltered (32uf mains and 16uf screens). The dual rectifier circuit ghosts the most. increasing the filtering destroys the tone and response of these amps IMHO. BTW UK is 50hz

[rp]

There were dual recto Marshall SLs?? Got a pict anyone?

[Leo_Gnardo]

I think I've mentioned this before: early Marshalls (especially Superleads) were ridiculously underfiltered and exhibit a lot of ghost notes when driven. These are sum and difference frequencies of the ripple and the note being played (and of the harmonics).

'Zackly true. When you hear Popeye humming along with your single note solos, hopelessly out of tune (Popeye not you) you know you got it!

Failing filters will do that too. An interesting effect to be sure.

[cxx]

Yes, PS modulation is part of the sound of a good amp. Not too much, but without it the amp sounds sterile and flat. Modulation is fundamental to hearing.

[Bob S]

Thanks for posting David.
I've been working on the assumption that for the first filter (reservoir) more is better. Then dinking with the dropper resistors & filter cap values after that.
Hmmm.
Not hum.
Interesting stuff.

[Firestorm]

There were dual recto Marshall SLs?? Got a pict anyone?

I was under the impression those never made it past prototype. If they exist they'd be crazy rare.

[David Root]

I've been trending lower on PS capacitance the last year or two myself, but keeping the reservoir cap relatively high.

I'll be reviewing this philosophy on PSUD2 as you can see the ripple difference from plates to screens easily there.

I would think the "goldilocks" solution is enough to kill ghosting but not enough to kill the "bouncy" feel. How this relates with rectification type, ripple cancellation in push-pull, and retaining control when in full-tilt boogie mode is a major juggling act I think, may be a "pick any two of three" situation.

Dumble amps are fairly highly filtered, as they were designed to be played full out in live gigs. If you lower the capacitance from D-specs they do loosen up nicely, but then you probably lose the control cranked to some extent.

Where does a choke fit, or not fit, in all this? The 5F6A has a choke, but the best sounding 30W amp I have built was a 4-6V6 with a 3K resistor where the choke would be, and a 60uF reservoir cap to two 5Y3s in parallel.