ProAudio: Setting Up a Subwoofer & Crossover Filters (PuTTY / Direct Commands)

Last updated: 23 Jul 2026

Each zone has a crossover filter that can pass only low frequencies, only high frequencies, or be disabled entirely. This is what lets a subwoofer handle the bass while the main speakers handle everything else, without either one straining or distorting. Both the filter type and the crossover frequency have to be set before the filter is enabled.

The examples below assume the main stereo speakers are on Zone 1 and the subwoofer is on Zone 2. Configuring via Control4 or the Config Tool instead? See Setting Up a Subwoofer (Control4) or Setting Up a Subwoofer (ProAudio Config Tool).

Setting up a subwoofer zone? It should usually also be locked to its paired speaker zone so it follows the same source and volume changes — see Locking Two (or More) Zones Together (PuTTY).

Setting the Filter Type

Send FTYPZ to set the filter type and slope for a zone:

Value	Filter
0	Disabled — filter bypassed
2	12 dB/Octave Low Pass Filter
3	12 dB/Octave High Pass Filter
4	24 dB/Octave Low Pass Filter
5	24 dB/Octave High Pass Filter

^FTYPZ @1,5$    ; set the stereo speakers to a 24dB/octave high pass filter 
^FTYPZ @2,4$    ; set the subwoofer to a 24dB/octave low pass filter

If these don't mean much yet, that's fine — as a starting point, use 4 (24 dB/Octave Low Pass) on the subwoofer zone and 5 (24 dB/Octave High Pass) on the main stereo speakers zone. The 12 dB vs. 24 dB choice controls how sharply the filter cuts off frequencies beyond the crossover point — it's safe to experiment and listen for what sounds best.

Setting the Crossover Frequency

Send FFRQZ to set the crossover point — the frequency where the subwoofer hands off to the main speakers:

1 = 50Hz	9 = 79Hz	17 = 126Hz	25 = 200Hz
2 = 53Hz	10 = 84Hz	18 = 133Hz	26 = 212Hz
3 = 56Hz	11 = 89Hz	19 = 141Hz	27 = 224Hz
4 = 59Hz	12 = 94Hz	20 = 150Hz	28 = 238Hz
5 = 63Hz	13 = 100Hz	21 = 159Hz	29 = 252Hz
6 = 67Hz	14 = 106Hz	22 = 168Hz	30 = 267Hz
7 = 71Hz	15 = 112Hz	23 = 178Hz	31 = 283Hz
8 = 75Hz	16 = 119Hz	24 = 189Hz	32 = 300Hz

Both zones can be set in a single command using the multi-@ shorthand:

^FFRQZ @1@2,16$    ; set the crossover frequency for both zones to 119Hz

Both the subwoofer and the main speaker zone should be set to the same frequency. It's typically somewhere between 100 Hz and 150 Hz, though the full range runs from 50 Hz to 300 Hz — this one is also open to listening tests, so experiment for what sounds best.

Both the filter type and the crossover frequency must be set for the filter to actually engage. If either FTYPZ or FFRQZ is left at 0, the crossover filter stays disabled — even if the other one has a value set. There's no error response for this, so if a filter doesn't seem to be doing anything, check that both commands have been sent.

Backing Up the Filter Settings

Back up after every change. Once your filters are set, send:

^SS 512$    ; backup zone settings

Without this, a power outage can silently revert your filter settings.

Need help with your subwoofer setup?

Our support team can help troubleshoot command syntax or crossover filter issues.

UK: 01202 413 610 | US: (858) 748-8250 | support@pulse-eight.com

ProAudio: Setting Up a Subwoofer & Crossover Filters (PuTTY / Direct Commands)

Setting the Filter Type

Setting the Crossover Frequency

Backing Up the Filter Settings

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