ValhallaRoom V1.0.6: Introducing Dark Room

I have just released version 1.0.6 of ValhallaRoom. You can download the demos from the usual place, and all current ValhallaRoom customers should have received a link to the updates (send me an email if you haven’t received your links yet).

In addition to a few bug fixes, version 1.0.6 introduces a new reverb mode to ValhallaRoom: Dark Room. This new reverb departs from the high fidelity path taken by the other 4 reverb modes in ValhallaRoom. It is deliberately low-fi, with noisy interpolation, no high frequencies above 11 kHz, and a late reverb that can have a low initial echo density. It also has a wide stereo image, a clear decay with lush randomized chorusing, and sits in a mix quite nicely. An added bonus is that the CPU is significantly lower than the other ValhallaRoom reverb modes.

Why add a lo-fi reverb mode to ValhallaRoom? I’m not really sure. After doing this for about 12 years, I’ve learned to follow my instincts on this stuff, even if it takes me in strange directions. Plus, I wanted to add something new to ValhallaRoom, as a way of saying thanks to all of the customers who have supported my work.

I was also inspired by some recent studies of the Lexicon 224, the EMT250, and other vintage reverbs. These early digital machines often had very noisy interpolation, sparse initial echo density (at least by modern standards), and sampling rates that seem primitive today. They also were useful for creating a “larger-than-life” sound, that is described to this day as warm and spacious. I noticed that a lot of these classic reverbs had a very limited frequency response, so I figured it would be worth adapting some of these old-school limitations to the more modern algorithm architectures found in ValhallaRoom.

Dark Room has identical controls to the other reverb modes, but produces a noticeably different initial sound. With Early Send set to 0, the Late Decay can have a marked amount of initial “flutter” or “grain,” similar to the 224 Concert Hall with the Diffusion control set low. A few usage tips:

  • The Late Size control can be used to adjust the speed of the “flutter,” with larger sizes corresponding to more obvious and slower echos.
  • By setting Early Send to 1.0, and adjusting the Early Size to 40 msec or later (depending on the Late Size), the flutter in the Late reverb can be totally eliminated. This is similar to how the Diffusion control works in older Lexicons, but with the advantage that the Early reverb has far less coloration than the series allpasses used for the diffusors in many “classic” reverbs. The Late Size can then be adjusted to get the desired stereo width – this can get really big.
  • Setting DEPTH to 1.0 results in the most “vintage” sound, while values less than 1.0 allow the user to dial in some early reflections.
  • With Early Send set to 1.0, and using larger Early Size values (>100 msec), the Late Reverb will have a slower initial attack. This is similar to how the Depth control worked on the 224 and 224X/L, as well as the Shape and Spread controls on the 480L and later reverbs.
  • The Late High Mult and Late High Xover have an effect on the initial tone of the late decay, similar to the Concert Hall algorithm on the 224XL and the Small/Large Concert Hall B on the 224. By setting High Mult to 0.1X, the user can simulate the -6dB/octave filters used on these older boxes.
  • Turn up the Early and Late Mod Depth when using Dark Room. The older algorithms used a LOT of pitch modulation to avoid metallic decays. The Dark Room algorithm uses a different architecture that is less prone to sounding metallic, but if you want that big, lush, spacey decay, modulation is a must.

Here’s a preset that can be used as a good starting point for the Dark Room reverb mode:

<ValhallaRoom pluginVersion="1.0.6" presetName="DarkStartingPoint" mix="0.289999992" predelay="0" decay="0.0265265256" HighCut="0.58523488" earlyLateMix="1" lateSize="0.720000029" lateCross="0.25999999" lateModRate="0.202020198" lateModDepth="0.430000007" RTBassMultiply="0.413333327" RTXover="0.0666666701" RTHighMultiply="0" RTHighXover="0.410067111" earlySize="0.0581581593" earlyCross="0" earlyModRate="0.0909090936" earlyModDepth="0.800000012" earlySend="1" diffusion="1" type="0.416666657"/>

ValhallaRoom Tips and Tricks: Cathedrals

The 1.0.4 version of ValhallaRoom added a set of Cathedral presets, that were dialed in from published acoustic measurements of various Italian cathedrals. A few hints in dialing in a cathedral sound:

  • Turn DECAY up to correspond to the midrange decay rate. Gothic cathedrals can have decays up to 12 seconds long, while cathedrals from other eras tend to be smaller and have shorter decay times.
  • Late Size should be set to a high setting, to reflect the high modal density of these spaces.
  • The Early Size control should be used to generate a bit of a “fade-in” for the decay. Due to the large size of cathedrals, it takes a fair amount of time for the energy to build up in the space, which translates to a slow attack for the decay time. A good rule of thumb is to use an Early Size setting of 1/20th of the decay time (up to 500 msec or so for truly large cathedrals).
  • In order to get the “fade-in” effect from Early Size, set Early Send to 1.0, and DEPTH to 100%.
  • The Late High Mult should be set to a low value, such as 0.1x. The sheer volume of air contained in a cathedral adds a huge amount of high energy loss.
  • Set the HIGH CUT and Late High Xover to get the required amount of brightness in the sound. Lower frequencies would be more realistic, but higher frequencies might be better for that “heavenly” sound.
  • For a realistic sound, leave the Early Mod Depth low, but don’t be afraid to turn up the Late Mod Depth. In order to properly capture the modal density of a cathedral, a digital reverberator would have to use several minutes of delay memory, which would put the CPU and memory consumption well outside of the real-time range for any modern computer. Modulated delays are a good way of creating the impression of higher modal densities. Plus, they sound purty.


ValhallaRoom Tips and Tricks: Unnatural Hall Reverbs

In one of my previous posts, I described the characteristics of “real-world” concert halls, and how to emulate them with ValhallaRoom. In general, real concert halls have a fairly fast onset of reverberation, a decay time between 1.6 and 2.1 seconds, and a somewhat longer decay time at low frequencies than at mid-frequencies. A realistic emulation would use subtle amounts of modulation, in order to create the perception of a high modal density without pitch change.

This is all fine and dandy for real concert halls, but what about unrealistic concert halls? The earliest commercial reverbs, the EMT250 and the Lexicon 224, were both created in order to emulate concert halls. With the limited amount of memory available for delay lines, both of these reverbs turned to large amounts of time variation in order to avoid metallic decays. The sonic results were big, washy, chorused decays that could stretch to 70 seconds and beyond. No “real” concert hall sounds like this – but it is a great sound. In addition, hardware units like the 224, 224XL and 480L had the ability to artificially elongate the attack portion of the reverb, such that the reverb sound would “fade in” to a much greater degree than a real hall. Not realistic, but useful for creating a bit of separation between an input signal and the reverb.

Fortunately, ValhallaRoom excels at unnatural halls, in addition to emulating the “real thing.” A few tips for dialing in an unnatural, vintage digital hall sound:

  • Set DECAY to whatever feels right. Many of the “Concert Hall” presets of classic digital reverbs have decay times of 6 seconds and up.
  • Use the LATE Bass Mult to dial in the required clarity of the decay. Setting this <1.0X will result in a reverb that gets more trebly as it decays, which can be a nice sound.
  • Turn up the modulation depth! Both Early Mod Depth and Late Mod Depth can be cranked up for that seasick decay. For less obvious detunings, use lower Mod Depth settings, but higher Mod Rates.
  • The Bright Hall reverb mode can get much deeper and random modulations than the other modes.
  • Set Early Send to 100%, Early Size to >100 msec, and DEPTH to 100%. The Depth control in early Lexicon reverbs, and the Shape/Spread controls in later Lexicons, allowed the user to dial in a slow attack on the reverb. By running the Early reverb into the Late reverb and using a large Early Size setting, you can create a reverb that fades in at the rate determined by the Early Size.
  • The Early Diffusion control can be set to lower values, to emulate the grainy sound that many of the early reverbs had during the initial attack phase.
  • Set HIGH CUT to somewhere between 5000 and 8000 Hz to simulate the dark sound of early, low-sampling rate reverbs.

The following preset implements a big digital hall sound:

<ValhallaRoom pluginVersion="1.0.5" presetName="BigDigitalHall" mix="0.425000012" predelay="0.0240000002" decay="0.0730730742" HighCut="0.44697988" earlyLateMix="1" lateSize="0.730000019" lateCross="0.709999979" lateModRate="0.155555561" lateModDepth="0.460000008" RTBassMultiply="0.166666672" RTXover="0.0787878782" RTHighMultiply="0.377777785" RTHighXover="0.474496633" earlySize="0.255655646" earlyCross="0.0299999993" earlyModRate="0.143434346" earlyModDepth="0.370000005" earlySend="1" diffusion="1" type="0.25"/>

Den (from the Gearslutz forum) posted this preset, reminiscent of the sounds of the Lexicon 224 Concert Hall algorithm:

<ValhallaRoom pluginVersion="1.0.1" presetName="BladeRunner" mix="1" predelay="0" decay="0.150750756" HighCut="0.294630885" earlyLateMix="1" lateSize="0.949999988" lateCross="0.150000006" lateModRate="0.191919193" lateModDepth="0.200000003" RTBassMultiply="0.666666687" RTXover="0.0494949482" RTHighMultiply="0.25555557" RTHighXover="0.289261758" earlySize="0.235135138" earlyCross="0.0199999996" earlyModRate="0.169696972" earlyModDepth="0.129999995" earlySend="1" diffusion="1" type="0.25"/>

A quick example of piano played through the above setting (piano played by Den):

Here’s a really big “concert hall” setting:

<ValhallaRoom pluginVersion="1.0.5" presetName="VideoIntro" mix="0.507000029" predelay="0" decay="0.300000012" HighCut="0.344966441" earlyLateMix="1" lateSize="0.579999983" lateCross="0.150000006" lateModRate="0.088888891" lateModDepth="0.280000001" RTBassMultiply="0" RTXover="0.113131315" RTHighMultiply="0" RTHighXover="0.2966443" earlySize="0.0440440439" earlyCross="0.0199999996" earlyModRate="0.169696972" earlyModDepth="0.129999995" earlySend="0" diffusion="1" type="0.25"/>

A simple electric guitar phrase (which was used on Gearslutz to test many reverb algorithms) through ValhallaRoom with the above settings:

UPDATE 1/2012: I just reread this blog post from last year (thanks to a link-back from an interesting blog post at The DIY Recordist). It is worth noting that ValhallaRoom has several new reverb modes that are well suited for emulating vintage digital halls. DarkRoom, Nostromo and Narcissus are reverb modes that are designed to have the “dark” coloration of the older reverbs, as well as a more gradual onset of echo density, noisier interpolation (to emulate the reduced bit width coefficients of the older boxes), and heavy randomized modulation.

Death Cab for Cutie on VH1 tomorrow night. Special Appearance by ValhallaRoom.

Don Gunn just sent me a link to one of his latest projects – mixing a live performance by Death Cab for Cutie that will be shown on VH1’s Storytellers this Friday at 9pm. A few links (which I can’t embed here for some reason, so just click ’em):

Storytellers Sneak Peak: Death Cab for Cutie

“Title and Registration”

Three instances of ValhallaRoom were used for mixing the live musical performances – two vocal reverbs (one long, one short) and a drum room reverb. Don was kind enough to share the .vpreset settings that he used:

<ValhallaRoom pluginVersion="1.0.4" presetName="DCfC-short vocal" mix="1" predelay="0.190799996" decay="0.00650650635" HighCut="0.368456364" earlyLateMix="0.483999997" lateSize="0.109999999" lateCross="0.289999992" lateModRate="0.0545454547" lateModDepth="0.200000003" RTBassMultiply="0.333333343" RTXover="0.0909090936" RTHighMultiply="0.444444478" RTHighXover="0.530201316" earlySize="0.0238238238" earlyCross="0.699999988" earlyModRate="0.0383838378" earlyModDepth="0.0599999987" earlySend="0.109999999" diffusion="0.75999999" type="0.25"/>
<ValhallaRoom pluginVersion="1.0.4" presetName="DCfC-long vocal" mix="0.976999998" predelay="0.0494000018" decay="0.0200200193" HighCut="0.382550329" earlyLateMix="0.893000007" lateSize="0.899999976" lateCross="0.360000014" lateModRate="0.12525253" lateModDepth="0.300000012" RTBassMultiply="0.333333343" RTXover="0.062626265" RTHighMultiply="0" RTHighXover="0.597315431" earlySize="0.0222222228" earlyCross="0" earlyModRate="0.169696972" earlyModDepth="0" earlySend="1" diffusion="1" type="0.333333343"/>
<ValhallaRoom pluginVersion="1.0.4" presetName="DCfC-drum room" mix="1" predelay="0.0199999996" decay="0.0145145142" HighCut="0.442281872" earlyLateMix="0.653999984" lateSize="0.839999974" lateCross="1" lateModRate="0.0343434326" lateModDepth="0.439999998" RTBassMultiply="0.333333343" RTXover="0.0909090936" RTHighMultiply="0.444444478" RTHighXover="0.530201316" earlySize="0.192192197" earlyCross="0.100000001" earlyModRate="0.0909090936" earlyModDepth="0.0500000007" earlySend="0" diffusion="1" type="0.25"/>

It is nice to hear ValhallaRoom used in a live sound context, processing “real” instruments. Thanks, Don!

ValhallaRoom Tips and Tricks: Realistic Concert Halls

ValhallaRoom was named for its ability to get realistic room sounds. From this perspective, a concert hall is nothing more than a really big room. The physics and reverberant characteristics of concert halls have been studied extensively in the last century, starting with the work of Wallace Sabine (the acoustic consultant for the design of Boston Symphony Hall) and continuing with the work of Leo Beranek, Yoichi Ando, Manfred Schroeder, and many other acoustic researchers.

Concert halls that are highly ranked by classical music listeners tend to have the following characteristics:

  • A mid-frequency decay time of 1.6 to 1.8 seconds for music from the “Classical” period (1750 to 1820), and around 1.9 to 2.1 seconds for music from the “Romantic” period.
  • An initial time-delay gap at or below 25 msec. This is the time between the direct sound and the first reflection, and produces a sense of “intimacy” for shorter settings. This is why the “shoebox” shaped halls tend to be preferred by conductors and audiences – the initial lateral reflections start rather quickly, due to the relatively short distance that sound has to travel from the orchestra to the side walls to the listeners.
  • “Warmth,” in that the bass tones are strong. This translates to a low-frequency decay time that is somewhat longer than the mid-frequency decay time.
  • Spaciousness, in that the sound seems to come from a space wider than the instrument making the sound. This tends to be tied into phase differences in the signals hitting the left and right ears (which is often referred to as the IACC, interaural cross-correlation).
  • Envelopment, in that the reverberation appears to come from all directions, rather than from limited directions. In practice, this means that an ideal hall will mix the reflections together rather quickly, and won’t have any strong discrete echos from any one location, or a part of the hall where the reverb hangs around too long (as can happen in cathedrals with high naves).

Starting with the above criteria, we can dial in a realistic concert hall preset in ValhallaRoom. A few general principles:

  • Set DECAY to 1.6 to 2.1, depending on the type of music that will be played in the space.
  • Set HIGH CUT to a fairly low frequency, between 4500 Hz and 7000 Hz, to simulate the air absorption in the space.
  • PREDELAY should be set to match the initial time delay gap of the hall being modeled, with 25 to 35 milliseconds being a more “realistic” setting, and shorter settings useful in generating intimacy.
  • The Early Size parameter should be between 20 and 50 msec, with Early Send turned up full and Early Diffusion at max, in order to product a diffuse onset of reverberation.
  • The Late Size should be set greater than 0.5. The largest settings of Late Size may produce audible reflections, depending on the mode used, so tune this by ear.
  • The Late High Xover should be set low enough to cause a bit of rolloff in the decay (around 2 to 4 KHz), and the Late High Mult should be set to values significantly lower than 1.0X.
  • Late Cross should be set higher than 0.0, in order to simulate the envelopment of real halls. Late Cross values less than 1.0 will help retain the spatialization of stereo inputs, so this should be tweaked according to taste – start at 0.5 and work your way up or down.
  • The Early Mod Depth should be set to 0 for realism – higher values result in an unnatural panning of the early decay. The Late Mod Depth can be set higher than 0, and a little bit of modulation helps enhance the realism, but keep the Late Mod Rate in the 0.25-1.0 Hz range to avoid obvious pitch changes.

As a quick example, here’s a preset based on the measurements of Boston’s Symphony Hall, as described in Leo Beranek’s “Concert Halls and Opera Houses”:

<ValhallaRoom pluginVersion="1.0.5" presetName="SymphonyHall" mix="0.333000004" predelay="0.0671999976" decay="0.0180180185" HighCut="0.408053696" earlyLateMix="0.699999988" lateSize="0.74000001" lateCross="0.730000019" lateModRate="0.111111112" lateModDepth="0.720000029" RTBassMultiply="0.400000006" RTXover="0.0313131325" RTHighMultiply="0.533333361" RTHighXover="0.216778517" earlySize="0.0394394398" earlyCross="0.0299999993" earlyModRate="0.0909090936" earlyModDepth="0" earlySend="1" diffusion="1" type="0"/>

A quick tweak of the above, with a change of the Reverb Mode from Large Room to Large Chamber (just to shake things up), and we have a model of Vienna’s Grosser Musikvereinssaal:

<ValhallaRoom pluginVersion="1.0.5" presetName="GrosserMusikvereinssaal" mix="0.425000012" predelay="0.0240000002" decay="0.0194194186" HighCut="0.371140927" earlyLateMix="1" lateSize="1" lateCross="0.709999979" lateModRate="0.103030302" lateModDepth="0.720000029" RTBassMultiply="0.433333337" RTXover="0.0909090936" RTHighMultiply="0.5" RTHighXover="0.258389264" earlySize="0.0441441424" earlyCross="0.0299999993" earlyModRate="0.0909090936" earlyModDepth="0" earlySend="1" diffusion="1" type="0.333333343"/>

It is worth noting that I haven’t been to either of the above halls in person, so take the above presets as a rough starting point for creating your own concert hall presets.

ValhallaRoom Tips and Tricks: Short Drum Rooms

ValhallaRoom can be used to generate a room sound that works well with acoustic drums. Some recommending starting points:

  • Use the Large Room or Large Chamber Reverb Mode. These provide an earlier onset of echo density.
  • Dial in the initial “size” of the room with PREDELAY. A standard trick is to use 15 to 30 milliseconds of predelay for the ambience mikes in a “live” drum room.
  • DECAY should be set anywhere from 0.3 seconds to just over 1 second.
  • HIGH CUT can be used to tame the high frequencies of the decay. A real room is often much darker than one would think, so don’t hesitate to set this as far down as 5000 Hz. A brighter room can be set between 6 and 9 kHz.
  • The DEPTH control is used to dial in the ratio of early to late energy. A setting of 50% is a good starting point.
  • The Early Size setting can be used to add a short amount of early reflection energy to the attack when set to the 10-30 msec range. A setting of 50 to 100 msec is useful in obtaining a slight amount of “gated” sound, or for simulating the flattening of the decay envelope produced by heavy limiting/compression or tape saturation. Note that the overall decay time will be extended by the Early Size setting.
  • The Early Send control is critical in shaping the early attack of short room sounds. By setting Early Send to 0.0, the initial attack can be varied between flattened and an exponential decay, by adjusting the DEPTH control to crossfade between the Early and Late reverbs. With Early Send set closer to 1.0, the Early Size setting will dominate the decay of both the Early and Late reverbs, producing a flattening of the initial decay.
  • The Late Size should be set to 0.5 or less, to produce the highest initial echo density.
  • The Late Bass should be set to 1.0X or less. Lower values add clarity to the decay.
  • In general, a more realistic room sound is obtained by keeping the Early and Late Mod Depth set to 0.0. However, if you are wanting to emulate the super chorused “room” of the EMT250, by all means feel free to crank the Mod Depth up!

A few example presets (copy to your clipboard, and select “Paste from clipboard” in the Preset menu to hear the sound), starting with a realistic small room:

<ValhallaRoom pluginVersion="1.0.5" presetName="SmallishDrumRoom" mix="0.300000012" predelay="0.0299999993" decay="0.00300300308" HighCut="0.530201316" earlyLateMix="0.5" lateSize="0.330000013" lateCross="1" lateModRate="0.0909090936" lateModDepth="0" RTBassMultiply="0.153333336" RTXover="0.0909090936" RTHighMultiply="0.444444478" RTHighXover="0.530201316" earlySize="0.0193193201" earlyCross="0.100000001" earlyModRate="0.0909090936" earlyModDepth="0" earlySend="0" diffusion="1" type="0"/>

The next preset generates more of a compressed/gated early attack:

<ValhallaRoom pluginVersion="1.0.5" presetName="SmashedDrumRoom" mix="0.300000012" predelay="0.0299999993" decay="0.00300300308" HighCut="0.463087261" earlyLateMix="0.5" lateSize="0.49000001" lateCross="1" lateModRate="0.0909090936" lateModDepth="0" RTBassMultiply="0.153333336" RTXover="0.0909090936" RTHighMultiply="0.444444478" RTHighXover="0.530201316" earlySize="0.067467466" earlyCross="0.100000001" earlyModRate="0.0909090936" earlyModDepth="0" earlySend="0" diffusion="1" type="0.333333343"/>

By setting the Early Send parameter of the previous preset to 1.0, the early attack is extended, to produce a bit of a slapback echo effect.

<ValhallaRoom pluginVersion="1.0.5" presetName="SlapbackDrumRoom" mix="0.300000012" predelay="0.0299999993" decay="0.00300300308" HighCut="0.463087261" earlyLateMix="0.5" lateSize="0.49000001" lateCross="1" lateModRate="0.0909090936" lateModDepth="0" RTBassMultiply="0.153333336" RTXover="0.0909090936" RTHighMultiply="0.444444478" RTHighXover="0.530201316" earlySize="0.067467466" earlyCross="0.100000001" earlyModRate="0.0909090936" earlyModDepth="0" earlySend="1" diffusion="1" type="0.333333343"/>

ValhallaRoom Tips and Tricks: Gated Reverbs

Generating a gated reverb sound with ValhallaRoom is easy:

  • Set the DEPTH control to 0%, so that only the Early reverb is heard.
  • Set PREDELAY to 0.0 msec, so that the gated sound is generated by the Early energy only (the PREDELAY can be set higher for gated echos).
  • Set Early Diffusion to 100%, for maximum echo density.
  • Use Early Size to dial in the desired gate length in milliseconds.
  • Adjust High Cut for desired brightness
  • Use Early Mod Rate and Early Mod Depth to add chorusing to the gated reverb sound

Here’s a preset for a 150 msec gate. Copy the entire text, including the < and > tags at the beginning and end, and use the “Paste from clipboard” option in the Presets menu to bring the preset into ValhallaRoom.

<ValhallaRoom pluginVersion="1.0.5" presetName="Gate150msec" mix="1" predelay="0" decay="0.0190190189" HighCut="1" earlyLateMix="0" lateSize="0.5" lateCross="1" lateModRate="0.0909090936" lateModDepth="0.5" RTBassMultiply="0.333333343" RTXover="0.0909090936" RTHighMultiply="0.444444478" RTHighXover="0.530201316" earlySize="0.14914915" earlyCross="0.119999997" earlyModRate="0.0909090936" earlyModDepth="0" earlySend="0" diffusion="1" type="0"/>