Styled in all black and suitable for mastering purposes, the PQ from SPL is a parametric equalizer—specifically, it's a redesigned edition of their well-regarded Model 2050 SPL PQ Mastering Equalizer. It features stereo and dual-mono operation as well as five separate bands per channel. These bands can be individually instantiated and separately switched between Constant and Proportional Q modes.

An Auto-Bypass mode allows you to sit back within the sweet-spot of your monitoring setup and simply listen to your changes as the system automatically toggles between effected and unaffected signal. It does this at a rate of your choice. This EQ also features 120V Rail Technology, which helps elicits a mastering-quality technical performance from the unit in terms of headroom, dynamic range, and fine-detail reproduction. Its stepped knobs help you recall your exact settings between sessions. The unit utilizes XLR jacks for its inputs and outputs, and its dimensions ensure you can mount it within your rack.

5-Band Fully Parametric EQ    Dual-Mono or Stereo Operation    120V Rail Technology, Mastering Grade    Proportional or Constant Q    Auto-Bypass Mode    Stepped Knobs for Recall    Rack-Mountable

In each band, the frequency bandwidth can either be set to a static state, or one that grows/shrinks in relation to the amplitude of the cut/boost. In constant-Q mode, the selected bandwidth remains unaffected by the amplitude setting, making it a suitable choice for corrective applications (eliminating unwanted frequencies, for example). In proportional-Q mode, on the other hand, the bandwidth decreases as the amplitude of the band is boosted or attenuated, allowing for more musical choices.

Each channel provides five frequency bands, all fully parametric and independently selectable. Frequency ranges are: 

• LF (Low Frequencies): 10 to 330 Hz
• LMF (Low Mid Frequencies): 33 Hz to 1 kHz
• MF (Mid Frequencies): 128 Hz to 4.1 kHz
• HMF (High Mid Frequencies): 310 Hz to 10 kHz
• HF (High Frequencies): 760 Hz to 24 kHz

To be able to make an objective judgment of processed material, often it is best not to have to toggle between uneffected and effected signal yourself, as this can introduce psychological biases and remove you from the sweet spot of your setup whilst you make choices. Thus, you can induce Auto Bypass, an interval control that determines the time that needs to elapse before the unit toggles between the processed and unprocessed signals. Hard left is the shortest setting. To increase the interval, turn the knob clockwise.

The PQ Mastering Equalizer has been designed as an independent dual-channel equalizer and thus can be used to process two different mono signals at the same time. Nevertheless, you can also process a stereo signal with the link button, which allows you to manipulate both channels in tandem from the right channel.

Related Questions and Answers

Q: 1. How much should I use for a liter of water? I'm developing photograms/lumens

A: The instructions and use for Ilford PQ Universal Paper Developer (500ml) is, https://bit.ly/3sba8td .

Q: 2. Is this unit be mounted to a tripod?

A: Yes you can mount this to a tripod.

Q: 3. Can 2 Frontliners be connected for stereo operation of the processing modules?

A: Unfortunately the Frontliner is designed as a single channel unit with no linking features for dual or stereo operation.

Q: 4. Will this work on my iPhone 13 Pro Max while using the Peak Design Everyday case?

A: Yes, the Movo Photo SPL-WA 18mm Wide Angle Clip-On Smartphone Lens will also work with the Peak Design case.

Q: 5. Is this also compatible with the a6300?

A: I have just looked at the 6300.Just trying it out, it looks to me that the movie button on the 6300 is slightly different to the 6000, and it seems easier to use while still being away from your normal finger position. From what I see so far, it doesn't look like the Cineasy enhancement will be necessary. The 6300 is becoming more available so I suggest you try it in a store.

Q: 6. Can this be mounted to a tripod? The photo of the back shows what might be a tripod socket, just want to be sure.

A: There is a standard tripod socket on the bottom side of the mic.

Q: 7. What is the difference between this and the CM-130 that only costs $59.99? The specs are the same except that this one has lower bass response. What specifically is different in this model warrant double the price?

A: The CM-140 meets IEC 651 Type II & ANSI S1.4 Type II standards while the CM-130 model does not.

Q: 8. Can this device be used with line-level inputs (I think that's the correct term), like from a CD player? Thanks

A: Yes, this equilizer allows for balanced XLR line level or unbalanced RCA stereo line level inputs. A CD player would connect throught the RCA inputs.

Q: 9. Is this a unit with a +4dbu line level signal or a -10dbV line level signal? Secondly, if it operates on a -10dbV line level signal, can it be used with professional audio gear or must certain precautions be taken? Thirdly, is it switchable?

A: The Rolls RPQ160b - Parametric Equalizer features a +22dB max input and output level, which does not appear to be switchable. Further information can be found via the product's manual: https://bit.ly/3il7z2P

Q: 10. Can the noise be recorded and then uploaded to a computer with the level of noise?

A: The CM-170 is a meter that measures sound pressure level. You can record audio of the noise you are measuring but the recorded audio may differ from the live audio depending on the capabilities of the microphone and recorder. If you are trying to document a noisy environment to provide proof of the high sound pressure level, like loud noise from construction work, you may want to set up a camera or use a smartphone to record video that shows you actually measuring the level on the meter and also document the time and day it is taking place.