Analogue og – og -og…

uncleandelayimagePokey Sticks has been working on amplifier circuit design lately, peering into an oscilloscope for hours and thinking wistfully about transient distortion.  Though the purpose was to make amplifier circuits that follow changes in the signal very accurately, it shed a lot of light on interesting ways in which circuits often don’t…  Hence Pokey Sticks has decided to release into the wild a couple of plugins that were previously considered too rogue, difficult and dangerous. Get them on the Downloads Page. (win32 vst).

The first is Unclean Delay. Using the best of analogue and digital it can set a delay time accurately in milliseconds and uses the Pokey Sticks low level virtual analogue to process the echo. You can apply high pass and low pass filtering, a controllable amount of saturation and the amount of feedback. The important thing is that in Unclean Delay the filtering and saturation happens to the sound over again every time it repeats. That’s because a real, inaccurate tape delay would loose some of the highs and lows and distort the signal a little more every repeat as you hear a recording of a recording of a recording. So the echo sound becomes both increasingly mushed and increasingly complex as it fades away. A bit of measuring shows some vintage equipment is surprisingly dark sounding. Don’t be afraid to lowpass as low as 500Hz for some funky old stylee sounds. Scroll the digits on the left up and down to set the delay in milliseconds. The highpass and lowpass controls have a ‘big’ knob and a ‘fine tune’ knob. The frequency of the filter is the two added together – e.g. 1000Hz on the big knob plus 500Hz on the fine tune to make 1500Hz. The plugin comes in two flavours – ‘Unclean Delay’ for putting on the same track as the music and dialing in as much ‘wet’ as you want. ‘Unclean Delay Wet’ is for putting on a separate track and routing to and from it. The output is all ‘wet’ and no ‘dry’. It comes without presets, guarantees, house training etc but is capable of some very musical and authentic results 🙂

electroncloudimage

The second plugin is called Electron Cloud and is less tame still. Its about a subtle and less-talked-about property that valves have. Or may have. ‘Reliable Facts’ to follow at some later date! It’s an enhancer type of effect causing a particular kind of transient distortion. It’s very subtle and once again Pokey Sticks offers no guarantees or indeed much encouragement – its not easy to use well. It is a useful and perhaps unique part of the analogue-ness puzzle and can help deliver that hard to define ‘valve-ee’ warmth and emotional engagement. And Pokey Sticks just kind of feels like putting it out there… 🙂

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Plastic Fantastic

Bulova

Pokey Sticks probably best work of late has involved low level analogue simulation combined with echo / reverb sounds. Pokey Sticks would be happy to share the digital distillations however, they are a bit complicated! If you’re brave enough to try the (very wonderful) Unclean Delay and Very Sexy Reverb then drop a message a just ask 🙂 In the meantime, here’s something good, simple, efficient and useful!

Bulova is an enhancer. Based on the Pokey Sticks very special low level analogue simulation, it adds either pure 2nd harmonic distortion products or odd-order harmonic distortion products. The High Cut and Low Cut controls determine what part of the input sound feeds into the enhancer-o-bit. The Mix control determines how much non-linearity is added to it. It all comes out the other end,  original signal and enhanced bit together and Bobs your uncle! 🙂

Second harmonic is fairly subtle. Characteristic of some very old, single ended valve based equipment, it can add a little dab of smooth charisma. The hard-to-tell-its-there kind of effect. (unless you overdo it!)

Odd Order is far more visible.  Dial the Low Cut up towards say 1kHz-ish (1ish on the dial), roll off a little top end with the badly named High Cut to keep it smooth – try maybe ‘8’. Leave the dial on 10 to do no High Cutting, turn it down to 0 to cut lots! Should have called it ‘How Much Treble’ or similar… Add a sensible dab of the Mix dial. The result can be very like the way a nice, exiting sounding valve based push-pull amplifier would add harmonic components to the sound. In the case of the valve amp, an internal feedback loop is supposed to keep it linear but at higher frequencies and depending on design, phase shifts may make this loop less effective. That means that symmetrical (odd-order) distortion creeps in for only parts of the sound and bold and colourful noises come out 🙂

Download it as a VST from the Downloads Page

 

High Fidelity and White Lies

VSRNotch

Pokey sticks has been busy with all kinds of interesting stuff lately. There’s some very ‘arty’ things in process and once more free and downloadable are some plugin things from technical developments… Introducing the ‘Very Sexy’ range of filters! 🙂

If the agenda for the ‘Honest’ filters was accuracy and fidelity, the ‘Very Sexy’ filters bring you lies and fidelity. Assuming there can be such a thing. Like the Honest filters, they’re built on low level copies of analogue circuits. The difference is that they are modeled on different kinds of circuitry. Use of inductors was more common way back when people didn’t mind things being really big and heavy and expensive. Examples of inductor based filter circuits include some famous Abbey Road custom equipment and (parts of) the legendary Pultec equaliser. An inductor and a capacitor together form an electronic resonator. The resonance or ringing effect can be use to boost or cut selected frequencies in a signal that’s passing through it. Also, the resonance can be tuned to have a sharp and narrow (high Q) or a wide and flat (low Q) effect on frequency response.

The important thing at that time was it was a practical way of getting getting stronger, more dramatic EQ curves. A secondary effect is that there are a lot of ways in which the output signal is not honestly equivalent to the input signal. The resonance takes time to build up and to die away and even when the filter is being used to cut frequencies, something is being added. They have their own unique thing.

Thus the ‘Very Sexy’ filters. They can be unruly. High Q peaks have the potential to be very high and peaky indeed. And you can’t rely on them to actually be acting on the exact frequencies the dials innocently claim. But they can be very effective, sometimes bold and also shamelessly musical. Pokey Sticks hasn’t made much of an attempt to tame the rough edges. Partly because there’s lots that needs getting on with and partly because it just seems more fun that way! 🙂 They are of course modeled with care and detail, based on legendary hardware and designed to give excellently accurate, high fidelity performance of their careless misbehavior…

Get them via the downloads page

 

Honest Highpass update

screengrab sri off

The Pokey Sticks research department has been working on a whole bunch of exiting Sound-Stuff lately. There are some very pure processing whatsits based on low level analogue simulation. Distilling things to Platonic Purity(tm) has had the additional effect of bottling the essence of all kinds of colourations, flavours and resonances too! Applying these at will is very nice indeed 🙂 Inspired by said flavours, Pokey Sticks is also working on some enhanced ribbon microphone designs that with luck will bring a super smooth retro thing to vocals with a modern fidelity at the same time. Also possibly the greatest way of recording acoustic guitar everrrrr.

And the point of the post: The Honest Highpass filter is now available (free) as a VST plugin (previously only as a Reaper JS effect). See the previous post Free Filters Resonance and Punctuality for details. The complete set of Honest effects as VST soon. Also soon, some very nice coloured filters with analogue complexity…

Honest Highpass win32 VST

Honest Highpass manual

This software is provided ‘as is’ without any express or implied warranty. In no event will the author be held liable for any damages arising from its use. By downloading it you agree that you will be nice, kind and reasonable.

The Most Excellent Transformer

Most Excellent Transformer

Pokey Sticks proudly presents a tippy top new plugin! Free to download, delightful and yummy to listen to! (vst plugin for windows – apologies to mac people!).

Download Most Excellent Transformer win32 vst

The Most Excellent Transformer plugin is a high quality, analogue simulated model of a real world stereo transformer pair. The idea is that adding it to your signal chain inside the computer is just like adding one into the real world part of your gear. Only less of a pain. The sound of the transformer is an important and characteristic part of many pieces of equipment and is a less talked about part of the ‘tube’ sound. However, they are complicated in how they work and other plugins I have used just don’t sound like the real thing! Transformers have unique and characteristic ways they act on a signal. The distortion is highly frequency dependent – acting very much more on the low frequencies compared to the high. Typical valve and transistor distortions tend to squash the top of a wave peak, or both the top and bottom peaks. Transformers and other magnetic components tend to squash the front of the wave compared to the back, making it ‘lean over’. Deffo its own characteristic thing. In the sound, low frequencies cause harmonic products that then mix in with the upper bass and mid. It can be very subtle. Energy gets taken from the very lowest bass and put back a little higher up where it’s easier to hear and easier for speakers to reproduce. It can warm, focus, add a nice little bit of phatness. Products from the bass can reach up and mix with the mid which can smooth and soften it in a rather appealing way. Also doing that ‘glue’ thing to a mix, creating more of a sense of a single unified sound or whole. Or you can drive it till smoke comes out to make it fuzz and buzz!

Using it

The plugin is a model of a specific real world transformer, tweaked and tuned so that putting the plugin in your signal chain should both sound and measure like putting the real one in your analogue signal path. On top of that are two controls to give some flexibility and creative fun 🙂

The first is the drive control. Turning it up drives the transformer harder, causing more colouration. Depending on how bass heavy the signal is, at some point it’ll break up into obvious fuzz. Before that and depending on the music, distortion levels can be quite high without being very obvious to the ear  (at least until you get used to it). Similar quantities of transistor distortion would be very in-your-face. This is mostly a different and subtler thing! Turning the drive down keeps it cleaner of course.

The simple way to think of the second control is choosing how ‘big’ the transformer is. Turn the dial down for a bigger and thus cleaner transformer. A big transformer will take more drive and lower frequencies before it distorts.  Turn the dial up for un-bigness. Un-big transformers colour more for the same amount of drive and bass. In more detail, the setting on the second dial is the corner frequency of the high pass filter the transformer makes with the circuit that drives it. It rolls off the bass below that. Rolling off below 8Hz-or-so is not going to be a big deal in itself! More significantly, it also relates to what frequencies start to make it distort. At a higher setting, the transformer begins to distort at higher frequencies, sending distortion products higher up into the mid and treble and / or breaking into fuzz more easily on the lows. A lower setting and the signal can go deeper before significant distortion. For real world gear – very top end modern stuff may go as low as 2Hz. Simulating really super clean equipment is potentially a little pointless of course. Cheaper gear or retro equipment that never expected to see big sub bass will roll off higher. The default setting comes from measurements on my real transformer adding colouration to a whole mix. You may find around 8 to 20Hz a good sweet spot for adding to a whole mix, adding to each track for a cumulative effect, or adding to FX chains to bring that little bit of analogue colour. Back off the drive if it becomes too obvious. Individual instruments and more creative use may respond better to a bigger yank on either dial…

A quick note on high frequencies. I’ve seen plugins with a dial to add transformer distortion ‘sparkle’. Transformers add far more low frequency components than high and tend to thicken things! In real world cases- say between a microphone and preamp, a transformer can potentially stop the loss of high frequencies by correcting bad impedance matching, but thats actually just the absence of a different problem by restoring the correct eq! A little added top end can sound nice though, to balance out a phattened bottom end. Just add it to taste with your tone control of choice (the Pokey Sticks ones are excellent. Reaper JS versions linked on the previous page and soon to arrive in vst format too!) Magnetic tape certainly uses a lot of internal eq correction and a little finessing can get that nice touch of  lose-a-little-detail, gain-a-little-warm-presence thing that can come from good tape.

Transofrmers (and other magnetic things) tend to make a sine wave 'lean over'
Transformers (and other magnetic things) tend to make a sine wave distort front to back making them kind of lean over!

Free Filters, Resonance and Punctuality

Pokey Sticks has been refining some custom EQ plugins lately. Downloadable free from here. The limitation is they’re only for Reaper as JS effects at the mo. Hopefully, the Pokey Sticks Research Department will get around converting them to general vst plugins at some point…

So why design more filters? Problems and limitations showed up in most of the digital filters I was using. Despite price, reputation etc. Hidden complexities, quirks and shortcomings abound! It’s time to cut through the nonsense!

Bad behaviour is easy to come by in both digital and analogue EQ filters, particularly in the time domain. Typical digital techniques are prone to resonances. This means the filter rings like a sound source itself, adding things to the sound that weren’t there before and also blurring exactly when it starts and stops. Analogue designs can do this too. It’s not all bad of course – resonance in filters is sometimes used deliberately. It can help make sharper, more surgical curves in the frequency domain and resonant filters are also used as a creative tool. However, it is mostly just unwanted mess! For digital filters there’s extra problems too. Trying to make good EQ curves anywhere near the Nyquist frequency is a world of pain. See the attached image of a well respected filter trying to do a simple first order lowpass on a square wave with the knee frequency set to 19KHz at a sample rate of 44.1KHz. Instead of smoothly rounding the corner of the square, the filter overshoots then oscillates. Interestingly, it does actually result in the right frequency spectrum on average. That means it’ll look right on a frequency graph. Obviously though, it’s not the right shaped wave coming out and it does sound different to how it should. Under other conditions the same filter may behave just fine. For another example, see the image of a conventional filter trying to add high frequency gain to a square wave. It should pull up a smooth peak but you can see the jaggedy artifacts. The problems can be hidden, surprising and quite audible. Thus the agenda for the Pokey Sticks filters that don’t do that bad stuff…

The original, analogue high pass or low pass filter is very simple. Its a resistor and a capacitor or inductor. Its all passive, with no feedback mechanism so it can’t oscillate or overshoot. The way these electronic components behave can be described quite simply so the Pokey Sticks filters are essentially simulations of these circuits. The main trade off is that you can’t get really steep, ‘surgical’ EQ curves like that. Instead we’re talking about something that is smoother, gentler and more ‘analogue’ style in its nature.

A bit of tweaking and bingo, we’ve got nice ‘virtual analogue’ filters that wont produce long oscillations, weird jagged bits and other digital artifacts. Simple, accurate, good sounding and analogue stylee. The mid gain filter also naturally has a slight ‘Butterfly’ plot. Also known as the push-pull effect or pre-emphasis. It’s something the famous Pultec vintage EQ is known and loved for, resulting from its analogue capacitor and inductor filter network. A mono one will set you back several thousand pounds. So, all good then and almost job done. One last thing. If you work at sample rates below 88.2KHz there’s a quirk to deal with, so read on.

Basic theory is the digital sound inside the computer can’t contain any frequency higher than half the sampling frequency or sampling rate. The less obvious thing is that life is already getting tricky at frequencies before that. See picture for a 19KHz sine wave at 44.1KHz sample rate. Pretty sketchy! There’s only just enough information left to re-make the original smooth sine wave. A highest quality final output render from a good DAW can recreate the sine wave amazing well, but you can’t get that in real-time without significant latency. Lower quality reconstruction just introduces all those artifacts we’re trying to avoid. The ‘standard’ digital filters and the Pokey Sticks filters react in different ways to this problem. The ‘standard’ filters when faced with limited information can produce those weird results and jaggy twitches. The Pokey Sticks filters always produce good sounding, flowing waveforms without artifacts, but the steepness of the EQ slope is altered… So to prevent lies and surprises, if you’re working at sample rates below 88.2KHz you may find the filters refuse to set corner frequencies above 10KHz. It’s less of a deal than it sounds. The whole audio spectrum is still being properly acted on. For the low pass Pokey Sticks filter, the simple workaround is the mix slider. If you want to set a corner frequency of 15KHz but can’t. Set it at 10KHz and fade out the strength of the effect to about 50%. Now you’re cutting a bit less of the top end, pretty much just as you meant to. Using the mix slider will give quite near the same result as if you were setting the  corner frequency where you wanted in that top octave 10 – 20KHz band. The slope wont actually be as steep, but the audible difference is very subtle. At the same time, you’re living free from time smearing, ringing, aliasing and latency which definitely do have a noticeable impact on the sound! Better still, use sample rates of 88.2KHz or higher and there’s no issue!..

Band Gain plot
Band gain showing pre-emphasis dip. Setting 1KHz, 7.5db gain
Digital artifacts from a respectable filter. The curve should be smooth.
Digital artifacts from a respectable filter trying to add high frequency gain. The curve should be smooth.
Correct smooth curve from the Pokey Sticks filter
Correct smooth curve from the Pokey Sticks high shelf filter.
Messed up low passed square wave. 19KHz cut, 44.1KHz sample rate. The corner should round off but instead theres a lot of overshoot and ringing.
Messed up low passed square wave. 19KHz cut, 44.1KHz sample rate. The corner should round off but instead there’s a lot of overshoot and ringing. Well known, respectable filter.
The correct waveform from the Pokey Sticks low pass. Even with worst case conditions and the mix slider workaround its the right result without without weird problems!
The correct waveform from the Pokey Sticks low pass. Even with worst case conditions and the mix slider workaround, it’s correct, smooth and free from weird problems!
A sine wave near the Nyquist frequency - 19KHz wave at 44.1KHz sample rate. Not exactly smooth and even!
What a sine wave looks like near the Nyquist frequency – 19KHz wave at 44.1KHz sample rate. Not exactly smooth and even!

Here are the current batch of filters – a few more to come soon. They are in Reaper JS format – to install them, just put them in the proper folder. Probably something like C:\Documents and Settings\Your_computer_or_user_name\Application Data\REAPER\Effect

Comments and discussion welcome! 🙂

High Pass Filter download

Low Pass Filter download

High Shelf Filter with 6db gain download

Band Gain Filter download