• Considerations with Auto-Tune
• Input Delay Compensation in UAD Console
• Note on Aux channel usage in UAD Console
• Latency context from a player's perspective
• Calculating latency over Dante with Apollo x16D, e1x, and e2m
• Additional Plug-In Latency and Plug-In Specific Information
   

To achieve sonic design goals, some UAD plug-ins introduce additional latency in addition to the existing hardware I/O latency. When these plug-ins are used in a DAW or UAD Console, enabling delay compensation keeps your tracks synchronized in the timeline. Plug-in delay compensation also helps maintain phase alignment when using multiple sources in a session.

The latency added by UAD plug-ins is negligible, typically between 0-100 samples, depending on the plug-in and session sample rate. The additional latency of all UAD plug-ins is listed, in samples, in the tables below for reference.

For related information, see the “Latency & Delay Compensation” chapter in the UAD System Manual, and the “Latency & Apollo” chapter in the Apollo Software Manuals.

Considerations with Auto-Tune

Auto-Tune dynamically adjusts latency depending on the settings used. It’s important to note that due to the dynamic nature of Auto-Tune’s latency, it is not compensated for by delay compensation in your DAW or UAD Console. For this article, we are looking at Auto-Tune Realtime X and Auto-Tune Realtime Advanced specifically.

Classic Mode has the lowest latency, with 1-2 ms of additional latency at 44.1 kHz (approximately 50-100 samples). This additional latency time halves when you double the sample rate, so for live sound processing, running at 96 kHz can further minimize the latency added.

In Classic Mode, the lowest latency options are Soprano, Low Male, and Instrument. The Alto-Tenor option has a marginally higher latency.

Modern Mode has slightly higher latency, with 4-7ms of additional latency at 44.1 kHz (approximately 175-300 samples). Again, the latency time is halved if you double the sample rate.

In Modern Mode, the latency varies from lower to higher as follows: Soprano, Low Male, Alto-Tenor, and then Instrument.

Input Delay Compensation in UAD Console

Input Delay Compensation aligns all inputs up to a prescribed total latency in samples, and is enabled by default. You will want to enable Input Delay Compensation if you are using more than one mic to record the same source or adjacent sources. This ensures the input signals remain phase-aligned.  

In UAD Console

In UAD Console, which is the direct monitoring path, the amount of delay added by Input Delay Compensation is automatic. To maintain the lowest possible latency for phase alignment at all times, only the minimum amount of delay required to align an input is applied, up to the maximum value of the setting.

For example, when set to Short (100 samples) and 31 samples are required for compensation, then only 31 samples of delay are applied to the other UAD Console inputs.

In your DAW

In your DAW, which is the record path, the Input Delay Compensation amount is always added to all inputs, even if no active plug-ins require it. This additional input latency is reported by Apollo’s drivers, so it is automatically compensated by the DAW. Short and Medium delay compensation is generally not noticeable from a player performance standpoint. The latency is halved by doubling the sample rate.

Input Delay Compensation Values in UAD Console

Input Delay Compensation Exceeded Dialog

The “Input Delay Compensation Exceeded” dialog appears in UAD Console when the maximum compensation amount for a given setting is exceeded on a channel. If this occurs, to maintain phase alignment, you can either increase the Input Delay Compensation value or reduce the number of latency-introducing plug-ins on the channel. 

In some cases, having misaligned tracks may be acceptable, or you may desire minimum latency regardless of the misalignment it can introduce. For example, when monitoring single or isolated sources, and not using multiple mics on the same source. In these cases, delay compensation can be set to Off. Hence, the dialog is just a warning and not an error.

Some mastering-grade UAD plug-ins have higher than typical latency, and we do not recommend monitoring live inputs in UAD Console with these plug-ins: 

• Precision Multiband - Approximately 15,000 samples
• C-Suite C-Max - Approximately 630 samples
• Ampex ATR-102 - Approximately 2200 samples

Please note that the exact latency can vary depending on the sample rate being used.

Note on Aux channel usage in UAD Console

UAD Console’s Aux returns have 72 samples of additional latency when compared to the monitor outputs. This is necessary to maintain the lowest possible latency for the channel input signals. Because they cannot be compensated, aux buses are best suited for time-based effects, such as reverbs and delays.

Latency context from a player's perspective

Sound travels about 1.13 feet (0.34 meters) per millisecond, so 10 ms latency is the equivalent of sitting about 11.3 feet (3.4 meters) from a speaker.

Calculating latency over Dante with Apollo x16D, e1x, and e2m

When using an Apollo x16D and Dante peripherals, you must factor in Dante transport latency. This is defined by the capabilities of the connected device.  

For Apollo x16D, the Dante latency can be set to 0.25ms, 1ms, 2ms, or 5ms.  

For Apollo e2m and e1x, the Dante latency can be set to 1ms, 2ms, or 5ms.  

All devices on the Dante network must be capable of conforming to the same Dante latency to achieve the set Dante transport latency.

Here’s a real-life example using an Apollo x16D and an Apollo e2m, with the Dante latency set to 1ms:

• Live keyboards are connected to an Apollo e2m’s line input. 
• Then, sent over Dante to an x16d for UAD DSP processing. 
• Finally, returned to the Apollo e2m over Dante for monitoring with headphones.

The latency in this example can be calculated as follows:

• Apollo e2m’s A/D conversion adds .2ms  
• Dante transport latency adds 1ms  
• At 96kHz the x16D adds .8ms (+ any additional plug-in latency in samples)
  *note - this .8ms changes to ~1.5ms at 48kHz, but at 176.4 / 192kHz it’s still ~0.8ms  
• Dante transport latency adds another 1ms 
• Apollo e2m’s D/A conversion adds .2ms

So, the total will be 3.2ms at 96kHz (+ any additional plug-in latency in samples).

Please note that doubling the sample rate will halve the additional plug-in latency time, and changing the sample rate will not affect the Dante transport latency.  

Additional Plug-In Latency and Plug-In Specific Information

EMT 250, Lexicon 224, and Lexicon 480L use anti-aliasing filters for their A/D and D/A conversion that are not linear-phase filters; therefore, the emulations do not have a latency that is the same at all frequencies. Thus, they cannot report to the delay compensation engines a delay that is correct for all frequencies. The reported values are accurate at low frequencies, but become inaccurate at high frequencies.

For example, when EMT 250 is in the Delay program mode and the delay time and predelay values are set to zero, the plug-in output will not be completely cancelled when mixing with inverted polarity against an unprocessed track; high frequencies will still leak through. However, the latency through the dry side of the wet/dry mix and the latency when the plug-in is bypassed via the EMT 250 Power switch do not have this behavior and will be fully compensated by the DAW.

Please see our UAD DSP table below for details of additional latency incurred by each UAD DSP plug-in.

Note: UA-developed plug-ins are italicized.