I realize that it's needed to lower S/N, but has anyone actually tried making a flanger circuit with no pre/post eq?
Is it really a necessity, if you're not feeding the output to a distortion pedal?
It's not a "necessity", but keeping noise out of a flanger is tricky, so everything helps. Pre/De-emphasis is simple, so it's more a case that you might as well use it.
To some extent, it's a function of what delay range one is aiming for, what BBD one is using to achieve it, and the amount of resulting hiss and clock noise one expects at the output. A pre/de-emphasis strategy does not provide dynamic control of hiss, the way that downward expansion or gating would during moments when the input signal is low and does not mask hiss arising in the delay path. I think it is also fair to say that the most interesting parts of flanging are often in the higher ranges, such that pre-emphasis can potentially make them more audible. In other words, even if one omitted de-emphasis to reduce hiss, you might want to still include some pre-emphasis for a more pronounced flanging sound. I suppose that additional treble boost would also depend on how the feedback/regen is implemented.
Quote from: maxdm on August 09, 2022, 01:55:16 AMI realize that it's needed to lower S/N, but has anyone actually tried making a flanger circuit with no pre/post eq?
Yes. Students in my lab were in on the first BBD samples program mid-1970s. Breadboarding was awkward for them so they left-out the obvious EQ to start. The sound was hard to listen to.
Why would you leave it out? It costs little. It is in the fine tradition of phonographs, FM radio, and tape: real speech/music does not have a whole lot of highs, but that's where you hear the hiss. Pre-boost/post-cut is a massive improvement for a 20 cent cost.
Yes I did using a TDA 1022 - the noise flanged excellently!!
Quote from: StephenGiles on August 09, 2022, 05:19:28 PM
Yes I did using a TDA 1022 - the noise flanged excellently!!
Stephen might be half-joking, but he makes a very good point. Flanging really *does* emphasise any available noise, especially with high resonance settings. "Resonance" is basically high gain at a particular frequency, so no wonder. It makes keeping a flanger quiet a pretty difficult task.
Ignoring feedback, it would be best if the dry and wet have very similar frequencies present yes? That is, you wouldn't want the wet or dry paths to gain or lose content, only the wet is shifted in the delay line. The old two tape decks method would be working with similar sonic content.
If you want a fatter flange (no sniggering), then some pre-distortion of both wet & dry input would be best I think, then the pre-emphasis filter is band-limited for bass cut and Nyquist upper limit and the post de-emphasis filter bass boost and clock high cut. What of the dry path? If we take "dry" from after the pre-filtering and mix it back at the post filter, equality of content is preserved.
Often though, the Dry path goes around the filter-delay-filter blocks. Am I right?
Quote from: ElectricDruid on August 10, 2022, 08:12:36 AM
Quote from: StephenGiles on August 09, 2022, 05:19:28 PM
Yes I did using a TDA 1022 - the noise flanged excellently!!
Stephen might be half-joking, but he makes a very good point. Flanging really *does* emphasise any available noise, especially with high resonance settings. "Resonance" is basically high gain at a particular frequency, so no wonder. It makes keeping a flanger quiet a pretty difficult task.
It did turn out to be very noisy, especially when feedback was increased - a very short lived experiment!