[sdiy] Analog bandwidth

[Tom Wiltshire]

On 21 Feb 2014, at 20:18, cheater00 . <cheater00 at gmail.com> wrote:

> On Fri, Feb 21, 2014 at 9:02 PM, Tom Wiltshire <tom at electricdruid.net> wrote:
>> But then the question is (and the OP's original point was) "How high do you need to go?"
>> 
>> It is an interesting question. Most analog synths *don't* push a lot of energy into the high end, with roll-off caps set fairly conservatively, and 4-pole filters that only open to 18-20KHz as a maximum. Although an analogue ramp might theoretically have energy out to dog-bending frequencies, it certainly won't after it's been through a 4-pole filter and past several op-amps with a 6dB roll-off.
> 
> Ideally? Yes. Practically? Not so sure.

Naw, it doesn't. I've looked at it on the o'scope's fourier view. Agreed, analogue filters aren't perfect, but all those little 6dB roll-offs add up, and by the end of a signal chain, you can pretty much flatten the ultrasonics. Check it out if you're in doubt.

T.