20KHz hiss/noise peak in the output - Volca Keys
Moderators: Sharp, X-Trade, Pepperpotty, karmathanever
20KHz hiss/noise peak in the output - Volca Keys
The hiss is almost not audible but becomes extremely audible when using external effects such as octaver, certain reverbs, any post-recording pitch manipulation. It's independent from Volca volume and does not change when switching from AC adapter to batteries. Did anybody have the same problem? It can be cut down with certain filters or can be somehow dealt with in post production, but as I like to record live and use other synth (microbrute) and effects at the same time it becomes problematic.
I haven't noticed, but I wouldn't be surprised.
I haven't tried the Volca Keys with an octaver yet, but I have three different ones, so I will soon. I have experimented with the Korg Monotron through a cheap Behringer UO300 octaver, fed via a Danelectro Fish&Chips graphic equaliser (another guitar effect pedal), mostly to try to find out what the octaver liked as a signal. I fitted a pot to control the note on the Monotron, so I didn't have to hold my finger on it.
I made notes...
Short version: I suggest using a guitar EQ pedal, preferably one that doesn't add more hiss of its own than necessary. There's usually some, unfortunately. The Danelectro one is reasonably quiet.
I found it best to cut the lowest band, at 100Hz, to get rid of any mains hum that might be picked up (I get plenty, even running entirely on batteries), and cut anything above what's actually needed - in this case, the 3.2KHz and above band can be cut.
I also found it best to cut a little at the low end, below 800Hz, ramping down to zero (fully cut) at 100Hz.
I used an iPad 3 (with iOS 7) with an iRig guitar interface instead of the inbuilt mic (which doesn't work well for low frequencies), with some free oscilloscope software: "SoundLevel" and "Physics Oscilloscope" - both of those are available as iPhone apps. I forget which/ whether they're available as specific iPad apps, but it runs both.
Longer version of how I set the EQ. Bear in mind this was to find the best settings to suit that particular octaver, to help it track the note properly. Your equipment will differ:
"With the range switch (filter) in highest position:
Test with Korg Monotron (lowish batteries, probably):
With Danelectro Fish & Chips EQ, I can make it stable beyond C5, but tailing off from about A4 (440Hz), fading a lot by D5 (588Hz) and very low at Eb5 (around 625Hz). It keeps going, but at a very low level, beyond that - just sinking into the background noise, really.
Bb4 (466.6Hz) is pretty strong, for both octave drops.
Pretty good up to C5 though -
Danelectro F&S full up on Level, full down on the two highest bands and full down to no more than 1/4 on lowest band (100Hz); then about 2/3 on 2nd / next to lowest band (200Hz), ramping up to full on 4th (800Hz) & 5th band (1.6KHz).
The higher two sliders can be raised (3.2KHz & 6.4KHz), but it's probably inviting more tracking problems, and doesn't actually extend the useful range as an octaver by much. 3.2KHz to about half or even full is okay, with the Monotron, but might not be with some signals.
"
I haven't tried the Volca Keys with an octaver yet, but I have three different ones, so I will soon. I have experimented with the Korg Monotron through a cheap Behringer UO300 octaver, fed via a Danelectro Fish&Chips graphic equaliser (another guitar effect pedal), mostly to try to find out what the octaver liked as a signal. I fitted a pot to control the note on the Monotron, so I didn't have to hold my finger on it.
I made notes...
Short version: I suggest using a guitar EQ pedal, preferably one that doesn't add more hiss of its own than necessary. There's usually some, unfortunately. The Danelectro one is reasonably quiet.
I found it best to cut the lowest band, at 100Hz, to get rid of any mains hum that might be picked up (I get plenty, even running entirely on batteries), and cut anything above what's actually needed - in this case, the 3.2KHz and above band can be cut.
I also found it best to cut a little at the low end, below 800Hz, ramping down to zero (fully cut) at 100Hz.
I used an iPad 3 (with iOS 7) with an iRig guitar interface instead of the inbuilt mic (which doesn't work well for low frequencies), with some free oscilloscope software: "SoundLevel" and "Physics Oscilloscope" - both of those are available as iPhone apps. I forget which/ whether they're available as specific iPad apps, but it runs both.
Longer version of how I set the EQ. Bear in mind this was to find the best settings to suit that particular octaver, to help it track the note properly. Your equipment will differ:
"With the range switch (filter) in highest position:
Test with Korg Monotron (lowish batteries, probably):
With Danelectro Fish & Chips EQ, I can make it stable beyond C5, but tailing off from about A4 (440Hz), fading a lot by D5 (588Hz) and very low at Eb5 (around 625Hz). It keeps going, but at a very low level, beyond that - just sinking into the background noise, really.
Bb4 (466.6Hz) is pretty strong, for both octave drops.
Pretty good up to C5 though -
Danelectro F&S full up on Level, full down on the two highest bands and full down to no more than 1/4 on lowest band (100Hz); then about 2/3 on 2nd / next to lowest band (200Hz), ramping up to full on 4th (800Hz) & 5th band (1.6KHz).
The higher two sliders can be raised (3.2KHz & 6.4KHz), but it's probably inviting more tracking problems, and doesn't actually extend the useful range as an octaver by much. 3.2KHz to about half or even full is okay, with the Monotron, but might not be with some signals.
"
I own all four Volcas and the Keys version is indeed the noisiest of the whole batch. This is normal though and caused by the analog delay. Even though you can set the delay mix to zero, it's still part of the audio signal chain and causes the hiss.
Roland Juno-60, SH-101, TR-606, MC-505, Casio CZ-101, Yamaha DX100, DX11, Kawai R-50e // Korg R3, microSTATION, Monotribe, MS-20 Mini, SQ-1, minilogue, electribe sampler, Volca series: Bass, Keys, Beats, Sample, FM, Kick, Moog Theremin
-
Spheric El
- Platinum Member
- Posts: 795
- Joined: Mon Jul 21, 2014 7:32 pm
- Location: Liverpool
I would try not to worry too much about noise when adding effects.It's very common.My favorite reverb is very noisy in itself,but is never a problem in the over all mix and most external machines will create noise that can become your focus at high levels.It never detracts from the music.I've even made a feature of some noise when stumbling across it,by distorting it.Some artists make it their signiture.
It's normal for noise on the V Keys.
It's normal for noise on the V Keys.
Octavers need a clean signal, or they behave erratically. It's not a question of eliminating noise so it sounds less noisy; it's a question of getting the thing to work at all.
The Behringer UO300 stutters if it's given a signal with mains hum, or if the signal it's trying to work from drops below a certain level.
Each has its own quirks, but they're generally strictly monophonic. Give them much more than a clean single tone, and they go haywire. Chords, or a clean tone plus hum or some other noise at a different frequency, is too much for them to cope with, as a rule.
The Behringer UO300 stutters if it's given a signal with mains hum, or if the signal it's trying to work from drops below a certain level.
Each has its own quirks, but they're generally strictly monophonic. Give them much more than a clean single tone, and they go haywire. Chords, or a clean tone plus hum or some other noise at a different frequency, is too much for them to cope with, as a rule.
-
Spheric El
- Platinum Member
- Posts: 795
- Joined: Mon Jul 21, 2014 7:32 pm
- Location: Liverpool
Understandable. I didn't really make that clear. It's natural to assume octavers do what it says on the tin, but in my experience, you have to really struggle to get them to behave.
The Electro Harmonix Octave Multiplexer and the Behringer UO300 (and presumably the Boss OC-2 it's roughly based on) exhibit the same problems.
The Behringer SO400 (Boss OC-3 clone, allegedly) might be more tolerant but has problems of its own - weird digital noise and a strangely synthetic sound. That could work better with a synth than a guitar though. I need to experiment more.
I've recently acquired an Electro Harmonix MicroSynth, which has an octave up (done with full wave rectification) and quite a nice sounding octave down, but both of those are very fussy. Even playing a note on a guitar while another string is still sounding the last one, confuses the s**t out of it - it makes a noise like a robot farting. I'm having to learn to mute strings as soon as I've finished with the note, to get the full use out of that one. Again, it could work much better with a synth.
But yes, input filtering is a good start. The UO300 has a "High, Middle, Low" switch, which appears to be an input filter, but it doesn't go far enough. Restricting the signal to the general range it can actually handle, using a guitar EQ, makes a huge difference.
The Monotron is useful for finding out how to set the EQ, because it's easy to add a 10k pot and a 1k resistor (to GATE) to make a hands free tone generator - overriding the built in ribbon keyboard, but still allowing it to be used as well.
The Electro Harmonix Octave Multiplexer and the Behringer UO300 (and presumably the Boss OC-2 it's roughly based on) exhibit the same problems.
The Behringer SO400 (Boss OC-3 clone, allegedly) might be more tolerant but has problems of its own - weird digital noise and a strangely synthetic sound. That could work better with a synth than a guitar though. I need to experiment more.
I've recently acquired an Electro Harmonix MicroSynth, which has an octave up (done with full wave rectification) and quite a nice sounding octave down, but both of those are very fussy. Even playing a note on a guitar while another string is still sounding the last one, confuses the s**t out of it - it makes a noise like a robot farting. I'm having to learn to mute strings as soon as I've finished with the note, to get the full use out of that one. Again, it could work much better with a synth.
But yes, input filtering is a good start. The UO300 has a "High, Middle, Low" switch, which appears to be an input filter, but it doesn't go far enough. Restricting the signal to the general range it can actually handle, using a guitar EQ, makes a huge difference.
The Monotron is useful for finding out how to set the EQ, because it's easy to add a 10k pot and a 1k resistor (to GATE) to make a hands free tone generator - overriding the built in ribbon keyboard, but still allowing it to be used as well.