hello everybody
i'm trying to make a synth with pure data
i want to play it with a midi keyboard with my amp ( hartke 3500)(it's a bass amp)
programming the synth make no problem
the problem is the sound:
it's very bassy and the high frequency are low define
for example, when i synthetize a sawtooth with a comb filter, the knob of the filter change almost nothing on my amp(but it's ok on my hi-fi system)
maybe my programation is wrong?
i use fexpr~ (($f2*$x1[$f3])+$x1[0])/2
with -64<$f3<0 and -1<$f2<1
my question is what kind of amp is better for this : a PA or a bass amp?

another question:
i got a lot of foldover in the high frenquency note ( i got a 48 key midi keyboard)
in synthetising a modulated sawtoth
my sound card is a m-audio usb fast track 48kHz 16 bit
i never test with a 96kHz sound card but is the improvement very big with this kind of card?

And in general:
can i have a better sound in a commercial way(for example a clavia nord modular)
than a solution with pd + sound card

thanks for help me

Charles

I'd imagine that a PA would be better for this kind of situation. I think it should have a flatter frequency response.

When you say you get a lot of foldover at higher frequencies, do you mean that you're aliasing at these frequencies? A sawtooth has a lot of harmonics, so I think higher frequency notes would be more likely to 'foldover' into the negative frequency range. Maybe use the lop~ object and set it at a very high frequency. This would knock down any frequencies that happen to go past the nyquist frequency.

Hopefully this helps some.

maybe [hip~ 5] to remove dc?

Re: foldover, your sound card shouldn't matter. Check out J07.oversampling.pd in the audio examples to see how to make an antialiased waveform. Basically you compute the audio inside a subpatch at a higher sample rate, so the aliasing in the audible frequency spectrum is negligible, and then filter out the frequencies above that with a Butterworth filter. Just using a lop~ like HD suggests wouldn't work without oversampling because the foldover is already present in whatever a phasor~ at 44.1 kHz is outputting.

My guess on amps would be that a PA would be better, unless you've programmed a bass synth, in which case a bass amp might work well. I can dig the Pd-through-amp-coloration idea. I had custody of a friend's Fender Champ a couple of years ago, and Max/MSP synths sounded pretty great with it.