Review: P821 MDN Tape by Pulsar Modular

NoiseQuest’s Josh Turvey is back with another review, this time taking recently released emulation of Marc Daniel Nelson’s personal analog reel-to-reel Stephens 821 tape machine for a spin.

Summary

Pulsar Modular’s P821 MDN Tape plugin emulates the iconic Stephens 821 2” tape machine, remaining true to the subtle depth and transparency that catapulted the original device into audio folklore.

Pros:

Excellent low-end extension and representation.
Capable of both subtle and pronounced tape saturation.
Multiple controls and parameters to fine-tune and sculpt the overall tape effect.
Solid range of creative features (e.g. Modulation and Tape Delay).
The ‘Stage Focus’ feature does an impressive job of enhancing the panorama of the processed audio.
Exceptional ‘cumulative effect’ when placing multiple instances throughout the project, e.g. Individual Tracks, Mix Buses, and the Master Bus.

Cons:

Unless driving the Input to its extreme, users looking for more aggressive tape compression and saturation may find the plugin to be too subtle for their taste.
No ‘global bypass’ switch to toggle all instances of the plugin on and off simultaneously. This is a non-essential feature that would help to hear the subtle but prominent contribution the plugin makes to the overall mix.

Intro

Based in Antalya, Türkiye, Pulsar Modular has a long-established reputation for excellence that has grown with each addition to their catalogue of premium plugins, the latest of which is the P821 MDN Tape. Modelling the plugin on audio polymath, Marc Daniel Nelson’s personal unit, this processor emulates the Stephens 821—a veritable, ‘holy grail’ of analog tape recorders that’s been featured on legendary records by artists such as Pink Floyd, Fleetwood Mac, and Steely Dan.

Famed for its clarity, transparency, and its ability to add width, depth, and dimension to audio sources, Pulsar Modular’s emulation aims to bring those subtle intricacies to the digital domain. Below, we explore the inner workings of the P821 MDN Tape, and how it can benefit one’s workflow.

Design & Features

The P821 MDN Tape (see image below) packs all of its features into a skeuomorphic design that will be intuitive to users familiar with other tape emulation plugins.

Pulsar Modular P821 MDN Tape Design and Features

With all the panels open, the plugin presents its features in a convenient, one-page layout:

Header (Yellow Box): Plugin Settings, Presets, A/B Comparison, Bypass switch, Polarity switch, and Stage Focus (discussed below).
Shelving Filters and Bias (Red Box): Intuitive controls that affect the plugin’s frequency response and can be used to further drive the Input gain of the plugin.
Metering (Turquoise Box): The metre simultaneously displays the Input and Output stages of the audio signal.
Gain Staging (Green Box): Controls the Input and Output levels, as well as the audio routing within the plugin.
Tape Settings (Pink Box): Controls the simulated tape speed, as well as providing two tape formulas that respond differently depending on the audio source.
Tape Hiss (Purple Box): Optional noise that can be blended into the signal.
Modulation (Blue Box): Adds movement and variation to the tape signal.
Tape Delay (Orange Box): Capable of creating various delay effects, from short, slapback echoes, to longer, repeating delays.

Concerning the plugin’s general behaviour, multiple parameters can easily be switched in and out of the signal path by clicking on their circular LEDs to toggle that respective setting on and off. Colour is used to indicate the status of the parameter: Red (Off), Orange (Bypassed), and Green (On). This is an especially important consideration when using the Modulation effect, which must be actively disabled if no effect is desired.

Header

Within the header (see image below), the A/B Comparison (blue box), Polarity Switch (yellow box), and Stage Focus (red box) are the most notable features.

Comparing different plugin settings on the same audio source is particularly useful when applying subtle tape saturation throughout the mix, so having this built into P821 MDN Tape is a welcome workflow enhancement. Likewise, the Polarity Switch makes it easy to remedy any potential phasing issues when checking for mono compatibility. Finally, Stage Focus is a unique feature that switches between three modes to tighten and focus the sound stage, or progressively increase the stereo width of the plugin.

Meters and Gain Staging

The centre of the interface (see image below) is dominated by two VU Meters, as well as the potentiometers driving the Input and Output stages of the plugin.

Although not shown in the image, the meters simultaneously display both the input and output signals, which are indicated by black and red needles respectively. Similarly, the meters glow increasingly brighter when pushing the plugin into saturation, so Pulsar Modular have done an excellent job in communicating useful, visual feedback that guarantees accurate monitoring.

The Input and Output dials ensure ultimate flexibility when gain staging, allowing the user to drive the plugin into saturation with the Input, whilst balancing the Output level. The linking function (green box) automatically compensates for any level adjustments by inverting the Input and Output dials. This can be toggled according to taste, and it can also be triggered via pre-defined modifier keys when disengaged. Enabling the ‘Thru’ button (blue box) bypasses the tape head, thus routing the signal solely through the preamps and the filters. This can be useful when wanting to impart characterful volume boosts to an audio source without engaging the tape effect.

Tape Settings

Following on from the Gain Staging section, the Tape Settings (see image below) have a profound impact on the resulting audio output. The Tape Formula refers to the chemical composition of the tape, whilst the Tape Speed (IPS—Inches Per Second) determines the speed at which the tape moves across the tape head.

As a crude generalisation, higher numbers in both categories typically indicate better fidelity and greater transparency, with lower values associated with the vintage, low-fidelity qualities that tape emulations are famous for. In practice, these qualities are heavily determined by the type of audio source, especially when driving the Input of the plugin and tweaking the shelving filters and bias controls (discussed below).

The Hiss dial (yellow box) adds low-level noise to the signal, which varies depending on the chosen tape formula. This lends to the authenticity of the emulation, though it should be applied sparingly because it can quickly become overbearing when layered across multiple sources.

Shelving Filters and Bias

The fixed-frequency shelving filters (see image below) work with the aforementioned Gain Staging and Tape Settings sections, predominantly by exaggerating or curtailing the low and high portions of the frequency spectrum.

The routing switch (blue box), inserts the filter either at the Input (Pre) or Output (Post) stage of the signal chain. Boosting at the Input stage will increase the amount of tape saturation, which can have positive and negative consequences on the resulting audio.

Tape Machines are famous for attenuating high frequencies—particularly when using slower tape speeds—so it is common practice to boost the HI shelving filter at the output stage to compensate for any loss in this area of the frequency spectrum. The inclusion of the bidirectional ‘LO and HI Bias’ controls is a unique addition to the plugin that wasn’t featured in the original Stephens unit. Their inclusion affords the user yet another method to fine-tune the plugin, working in tandem with the input drive and the shelving filters to affect the harmonic saturation in each respective frequency band.

Both dials will have no effect when set to unity, but can either exaggerate (clockwise), or soften and smooth (counterclockwise) the saturation according to taste. All told, this section is essential in shaping the saturation colour, and timbre of the plugin.

Modulation

The Modulation panel (see image below) is crucial in imparting movement to the processed audio.

‘Wow’ (slow and rhythmic) and ‘Flutter’ (fast and erratic) are typically associated with the pitch fluctuations that are essential in simulating the authentic, vintage imperfections that result from mechanical wear and tape degradation over long periods of time. Pulsar Modular varies things slightly in this regard. Whilst ‘Wow’ pertains to frequency drift, ‘Flutter’ imparts random speed variations to the amplitude of the audio signal, thus resembling an irregular tremolo.

Nestled in between Wow and Flutter, the Slow/Fast flip switch dramatically alters the behaviour of the modulation section. ‘Slow’ restricts each parameter to gentler, more natural undulations, with ‘Fast’ causing the modulation to become more noticeable, thus expanding the plugin’s creative potential.

The ‘Flange’ button simulates the famous, psychedelic flanging effect that was created by modulating extremely short delay times. Its behaviour is influenced by the three, aforementioned modulation settings.

Engaging the ‘LO-FI’ function will produce a noticeable midrange emphasis. Its bidirectional dial tightens and repositions the bandpass region created by the plugin’s shelving filters (discussed previously). According to the manual, enabling ‘LO-FI’ also enhances the plugin’s imperfections (e.g. Hiss, Wow, and Flutter), further adding to the vintage nostalgia of the plugin.

As a final note on this section, the cumulative effect of modulation can quickly become unruly when layering multiple instances of the plugin throughout the mix. As a word of caution, it’s wise to limit the use of this section by disabling it when it’s not needed.

Tape Delay

According to audio lore, the iconic, Slapback Delay (a short, single-repeat echo) was an accidental discovery that resulted from mixing some signal from a tape machine’s ‘playback head’ back into the signal from its ‘record head’. The distance between the two heads generated a short, audible delay that simulated the characteristic echo that is now synonymous with tape delays. It therefore follows that many tape emulations include in-built delays (see image below) to pay homage to this effect, frequently including additional parameters to further fine-tune the overall effect.

Although most of the included options will be familiar to many users (e.g. Feedback and Blend), it’s worth noting that faster IPS settings result in shorter delays, which can be offset to impart swing and groove to the delayed signal. Additionally, the High and Low Pass Filters (HPF and LPF) help to position the delayed signal in the frequency spectrum, thus distinguishing it from the original audio source.

In Use

It is widely acknowledged that digital audio can suffer from being overly cold, brittle, and sterile, which is mainly because it lacks the non-linearities and harmonic distortion of analog gear. This is one of the primary reasons that nostalgia for the sound of bygone eras continues to increase, with many producers and mix engineers now relying solely on plugins to add controllable colour, warmth, glue, and saturation to their recordings.

This contrasts to the heydays of analog recording, where the reduction of noise and saturation in favour of ‘clarity’ and ‘transparency’ was a constant and delicate balancing act that pushed the innovation and technology of the time. It was in this landscape that the original Stephens 821 emerged in the 1970s.

With the possible exception of creative applications and parallel processing, tape recorders were not originally designed to be pushed into excessive saturation. It’s therefore unsurprising that the Stephens 821 immediately stood out due to its ability to remain largely free from noticeable artefacts and degradation—even when driving its input.

Understanding this context is the key to unlocking the full potential of the P821 MDN Tape plugin. Unless pushing its input dial to the extreme, the plugin produces a gentle saturation effect that glues, thickens, and warms the audio it’s processing. It therefore strikes a healthy balance between character and transparency, remaining true to its hardware counterpart. As a result of this behaviour, the plugin excels when subtly deployed across multiple tracks throughout one’s mix, where its cumulative effect adds life and dimension, whilst remaining clean, transparent, and unobtrusive.

Users looking to saturate the plugin for creative purposes can push the input, shelving filters (in ‘Pre’ mode), and bias controls for multiple variations in tone and timbre. Inserting preamp emulations, saturators, and gain utilities before the P821 MDN Tape in the signal chain will further drive the input of the plugin, which will exaggerate its saturation capabilities. It should be noted that this runs the risk of clipping the plugin, but it can be an excellent workflow for creative sound-design and parallel processing.

For newcomers wanting to get acquainted with the P821 MDN Tape, here’s a recommended, step-by-step workflow:

Insert the plugin onto a Mix or Master Bus. Drum Buses are often good candidates because they typically cover a broad frequency spectrum.
Turn off the Modulation and Tape Delay sections by ensuring that their LEDs are red.
In the Gain Staging section, ensure that the ‘Link’ mode is on and the ‘Thru’ mode is off.
Drive the Input to an extreme setting so that the plugin is pushed into saturation and its overall effect is exaggerated. Turn off the ‘Link’ mode and increase the Output dial if you require more volume.
Explore the different tape formulas and tape speeds, focusing on the impact each combination has on the final sound.
Boost and cut the Low and High shelving bands in the filter section, switching the mode between Pre and Post. Notice how the tape input is driven further into saturation when boosting in the Pre mode.
Boost and cut the Bias controls, focusing on how they impact the frequency response, especially in relation to the total amount of tape saturation being applied to the final signal.
Engage the Modulation and Tape Delay sections. Experiment with their parameters, observing how these settings influence the sound of the processed audio.
Once acquainted with each section, dial back the Input gain to taste and tweak each parameter accordingly.

Finally, due to the transparent nature of the plugin, it can sometimes be tricky to hear the subtle sense of depth and dimension it adds to the mix, especially when suffering ear-fatigue during long mixing sessions. Although this is an unorthodox request, a global switch to simultaneously bypass all instances of the P821 throughout the project would be an outstanding addition. This would make it easy to compare the mix with and without all instances of the plugin, thus highlighting the incredible impact it can have in creating depth, presence, and clarity.

Conclusion

Few of us will ever have the privilege of comparing this plugin to the original unit that it emulates, but it cannot be denied that Pulsar Modular’s interpretation demonstrates all the characteristics that made the Stephens 821 famous. The P821 MDN Tape excels at adding clarity, transparency, depth, width, and warmth to its source audio. It prioritises subtlety and nuance over aggressive, tape saturation, therefore making it an excellent candidate to insert on individual tracks, Mix Buses, and the Master Bus.

Taking all of this into consideration, the P821 MDN Tape represents another superb release by Pulsar Modular, thus adding to their ever-expanding catalogue of quality analog emulations.

Technical Info

The download, installation, and authentication process is straightforward. A user account is required.
Mac & PC are both supported, with options for VST3, AU, and AAX.
Pulsar Modular provides a comprehensive manual in multiple languages, which can be downloaded from the relevant webpage as a PDF.
The CPU usage is well optimised, but using multiple instances throughout the project may affect performance depending on the computer’s specifications.

Disclaimer: This review was conducted on a MacBook Pro M4 Pro with 48 GB RAM and 1 TB SSD (macOS Sequoia 15.4.1). User experience with the reviewed software may vary with different technical specifications.

Alternatives

Even including Impulse Responses (IRs) into the search, emulations of the Stephens 821 tape machine are extremely difficult to find. Exacting emulations aside, there is no shortage of excellent tape emulations available on the market, the following of which come highly recommended:

Tape Machine Collection (IK Multimedia)
Ampex ATR-102 (UAD)
Tape (Softube)
Flywheel (Fuse Audio Labs)
Tape Face (Kiive Audio)
Tape J-37 (Arturia)
Magnetite (Black Rooster Audio)

Thanks Josh for another comprehensive review! P821 MDN Tape is available to try for free for 15 days, and a perpetual license is priced $179 USD at the Pulsar Modular website.

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