Not wanting to be an old sourpuss,
but adding 6dB boosts to something at 30Hz is usually a good way to totally ruin a mix :) It is very hard to accurately hear stuff down there - forget trying it on headphones... and forget most speakers... and the modal bass response of most rooms will totally muck up what you're hearing too... move your chair two feet to the left and you'll hear something different.
I'd guess that all you'd be doing to the Polysix with this mod is making it eat up headroom in a mix or on a PA, to no good musical purpose (and very likely to a lot of musical detriment)
On the other hand, for those into Extreme Noise Terror and the 'brown sound', it would be fantastic :-D
David
--- In PolySix@yahoogroups.com, "Chromatest J. Pantsmaker" <chromatest@...> wrote:
>
> I play a lot of bass-heavy music. It would be super easy to add a
> switch for this mod. I look forward to trying this on my big
> subwoofers!
>
> On Tue, Aug 20, 2013 at 9:53 AM, chipaudette <chipaudette@...> wrote:
> > I finally followed-up on Tony's suggestion that C61 on KLM-368 appears to have no purpose and that it could be removed.
> >
> > When I look at C61, I also see no purpose. I see that it could possible attenuate the lowest bass frequencies. I was curious to see the effect of removing this component. Not wanting (yet) to permanently remove C61, I simply bypassed it with a single clippy jumper wire. Easy!
> >
> > The result appears to be ~6 dB more of the deepest bass frequencies (down in the 33 Hz neighborhood). That's deep.
> >
> > If you're interested in the mod, you can check out the details at:
> >
> > http://synthhacker.blogspot.com/2013/08/polysix-deeper-bass-bypass-c61.html
> >
> > If you've got good headphones or really good speakers, there's also an audio comparison.
> >
> > My conclusion is that maybe the Polysix doesn't need these super-deep frequencies. It is a fun change, but I'm not sure it's how I want it to sound all the time. I'll have to live with it for a while before I make my decision.
> >
> > Thoughts?
> >
> > Chip
> >
> > --- In PolySix@yahoogroups.com, Oakley Sound <oakleylist@> wrote:
> >>
> >> I've been following Chip's progress with interest. And his recent post
> >> on the dynamic noise reduction filter on the effects board spurred me
> >> onto to investigate further. I too have noticed that the P6 is somewhat
> >> duller than other synths and I had always assumed that with the ensemble
> >> mode off the output was as bright as it could be.
> >>
> >> Chip's findings that all four ensemble modes pass through the DNR filter
> >> was something I hadn't really thought about before.
> >>
> >> http://synthhacker.blogspot.co.uk/2013/02/mystery-circuit-polysix-post-effects.html
> >>
> >> In summary: the P6 has a 12dB/octave low pass filter that is set to
> >> around 600Hz (the actual value depends on whether the BBDs are engaged)
> >> when no notes are playing. This filter opens up when it detects audio
> >> from the voice card. As Chip noticed it takes a finite time for the
> >> filter to open and the filter doesn't always open fully in all cases. I
> >> measured the filter took up to 100mS to open fully. That's a significant
> >> loss of high frequency sound at the start of each note.
> >>
> >> Yesterday I went a stage further than Chip. Chip's mod basically forces
> >> the filter open. I decided to remove the filter from the circuit
> >> altogether. This has the advantage of no dynamic filtering (which is of
> >> dubious amenity) and reduces the circuit pathway that the audio has to
> >> go through. The LM13600 isn't a hi-fi part and removing it improves the
> >> signal quality.
> >>
> >> The mod:
> >>
> >> Remove links J28 and J29. Remove R115 and R109 (which disables the
> >> envelope follower). Remove C73 and C61.
> >>
> >> Link out, with a piece of solid core wire, the two left hand holes of
> >> J28 and J29. Now connect with a piece of insulated wire the lower of
> >> these now filled solder pads to the lower pad of C73. The filter is now
> >> bypassed.
> >>
> >> Link out, with a piece of solid core wire, the two holes of C61. This
> >> capacitor serves no useful job that I can see.
> >>
> >> Result: the P6 can be as bright as any synth. Percussive sounds ring out
> >> where they didn't before. String sounds are really very majestic - you
> >> can really pull off sounding like a string machine now. The slight
> >> increase in background hiss is not a problem for me.
> >>
> >> Tony
> >>
> >> http://takla-makan.bandcamp.com/
> >> http://www.oakleysound.com
> >>
> >
> >
> >
> > ------------------------------------
> >
> > Yahoo! Groups Links
> >
> >
> >
>