Reference¶

Specifications¶

Item	Specification
Model	HTP-1
Part Number	38788
Video Inputs	8x HDMI®
Audio-Only Inputs	2x analog stereo RCA, 3x digital coaxial, 3x digital optical, 1x AES/EBU, 1x ARC/eARC
Streaming Inputs	Roon Ready®, USB audio, Bluetooth®
Video Outputs	1x HDMI ARC/eARC, 1x HDMI
Audio Outputs	16-channel balanced XLR line outputs, max level 4.0 Vrms. Unbalanced stereo analog RCA Mix Out, with independent −100 to 0 dBFS digital level, mute, and power-on volume. The Mix Out (or an XLR sub output) can also carry the Seat Shaker signal.
Triggers	1x trigger input, 4x trigger outputs
HDMI Version / HDCP™ Version	2.0 / 2.3
Maximum Video Resolution	4K@60Hz UHD
Audio Performance	THD+N < 0.0005% (-106 dB) at 1.8Vrms, 20-20 kHz, AES17 Dynamic Range = 116dB, 4Vrms, 20 kHz BW, A-weighted Frequency Response = 20-20 kHz, +1/-0.2 dB
Supported Audio Codecs	Dolby Atmos®, Dolby TrueHD™, Dolby Digital®, Dolby Digital Plus®, Dolby Surround®, DTS:X®, DTS Neural:X®, DTS-HD Master Audio™, DTS-HD High Resolution Audio™, Auro-3D®, Auro-Matic®
Crossover	Variable 4th order Linkwitz-Riley
Room Correction/Equalization	Dirac Live® (Room Correction and Bass Management, included with HTP-1 ownership); Dirac Live® Active Room Treatment and Bass Control are separately licensed upgrades — up to 6 filter slots
Built-in Audio Correction	Bass and Treble tone controls, 16-band parametric equalizer with independent speaker control on each band, Channel Levels (per-channel trim), Bass EQ, Seat Shaker PEQ, Loudness compensation, Dialog Enhance, Night Mode
Connectivity	Wired 100BASE-T Ethernet, Wi-Fi®
Input Power	100 ~ 240 VAC, 50/60 Hz
Dimensions	17.1" x 5.7" x 12.0"

Signal Processing Flow¶

This diagram gives a rough idea of the signal flow inside of the HTP-1, from the input driver through decoding to the output driver. It dates from the original (2021) manual and predates Channel Levels, the Seat Shaker/Mix Out path, Bass EQ, and the current Dirac Live configurations described below.

Historical (2021) diagram

The diagram below shows the 2.x processing chain for each of the four Dirac Live configurations: no Dirac Live, Room Correction (RC), Bass Management (BM), and Bass Control or Active Room Treatment (BC/ART). A clearer picture of how the system operates helps you achieve the most accurate and effective calibrations for your specific needs.

Channel Signals and Speaker Signals¶

It is especially important to distinguish between channel signals and speaker signals. Audio leaving the decoder is organized into channel signals, one of which is the LFE (Low-Frequency Effects) channel. A channel signal is the decoded audio stream for one audio channel before bass management and other speaker-specific processing.

From there, the bass manager and other processing stages convert these channel signals into speaker signals that are sent to the physical loudspeakers. A speaker signal is the final processed signal sent to one physical loudspeaker after bass management, delay, trim, and other speaker-specific processing have been applied. Unlike a channel signal, it may contain audio originating from several decoded channels.

As part of this processing, delay and trim are applied to compensate for differences in speaker distance, sensitivity, and amplifier gain. The bass manager redirects bass from Small speakers and routes the LFE (Low-Frequency Effects) channel according to the speaker configuration. This may include combining redirected bass and LFE in one or more subwoofers, or routing the LFE channel to Large speakers when no subwoofer is configured.

Dirac Live provides four filter types. Depending on the selected filter, bass management is performed either by the HTP-1 or by Dirac Live. With the HTP-1's traditional bass manager, PEQ is commonly used to correct speaker and/or room response after bass management. However, when Dirac Live ART or BC performs bass management, applying PEQ after the Dirac Live processing can interfere with or even invalidate the calibration. Pre is therefore the default PEQ placement. A BC or ART calibration is created using the signal path that exists during calibration. Changes that alter the calibrated signal path, such as modifying active Post PEQ filters or changing PEQ placement, can invalidate the calibration.

Note that the HTP-1 bass manager and the Dirac Live bass manager are separate processing stages. When Dirac Live is off, or a Dirac Live RC filter is loaded, the HTP-1's traditional bass manager is used. When a Dirac Live BM, BC, or ART filter is selected, the Dirac Live bass manager becomes active. The active filter type is shown as a badge, with a legend, on the Calibration page; which bass manager is active—HTP-1 or Dirac Live—is badged on the Speakers page.

With an ART or BC filter loaded, PEQ placement is locked, whether it is Pre or Post. Switching placement, or editing user delay or user trim, is blocked because these changes would alter the speaker signals produced by the calibration. With Dirac Live RC and BM filters, these controls remain editable.

Delays and Trims¶

Dirac Live computes its own speaker delays and trims as part of calibration. The separate user-adjustable speaker delay and trim controls are set to zero during every calibration. This applies to RC, BM, BC, and ART. Whenever a filter is transferred to a slot, any existing user delay and trim settings are reset because the calibration was created with those controls at zero.

With RC and BM filters, user delay and trim can be adjusted again after the filter is loaded. With BC and ART filters, these controls remain locked because changing them would alter the speaker signals produced by the calibration.

The Channel Levels page adjusts channel trim upstream of the Dirac Live filters and other speaker-specific processing. These adjustments affect the channel signals before they are converted into the speaker signals produced by the calibration, so they do not compromise BC or ART.

IR Code Tables¶

The tables below illustrate the entire set of supported IR codes. The HTP-1 accepts NEC format remote codes at address 0x36C9. The first table lists the codes sent by the remote.

Note

Only the Volume Up and Down keys support the standard NEC repeat code for repeating these keys. All other keys do not support key repeat.

Codes Sent by the Remote¶

Function	NEC Code	Function	NEC Code	Function	NEC Code
Power Toggle	02fd	User Input 1	609f	Red	51ae
Vol Down	09f6	User Input 2	619e	Green	52ad
Mute Toggle	0af5	User Input 3	629d	Yellow	53ac
Vol Up	0bf4	User Input 4	639c	Blue	54ab
Mode None	1be4	User Input 5	649b	A	55aa
Mode Dolby Sur	1ce3	User Input 6	659a	B	56a9
Mode Neural-X	1de2	User Input 7	6699	C	57a8
Mode Native	1ee1	User Input 8	6798	D	58a7
Mode Auro	1fe0	User Input 9	6897
Preset 1	03fc	Night Toggle	40bf	Last Input	44bb
Preset 2	04fb	Dialog Up	41be	BT Pair	59a6
Preset 3	05fa	Dialog Down	42bd	HDMI+	4db2
Preset 4	06f9	Dirac Toggle	47b8	SPDIF+	4eb1
Info	43bc			Analog+	4fb0
Dim	45ba	Loudness Toggle	5aa5	Stream+	50af

The second table lists other codes recognized by the HTP-1.

Other Codes Recognized by the HTP-1¶

Function	NEC Code	Function	NEC Code	Function	NEC Code
Power Off	25da	TV Input	0ef1	In Analog 1	27d8
Power On	26d9	In HDMI 1	0ff0	In Analog 2	28d7
Mute On	4bb4	In HDMI 2	10ef	In Optical 1	29d6
Mute Off	4cb3	In HDMI 3	11ee	In Optical 2	2ad5
Loud On	3ac5	In HDMI 4	12ed	In Optical 3	49b6
Loud Off	3bc4	In HDMI 5	13ec	In Coaxial 1	2bd4
Night On	3cc3	In HDMI 6	14eb	In Coaxial 2	2cd3
Night Off	3dc2	In HDMI 7	15ea	In Coaxial 3	48b7
Dirac On	3ec1	In HDMI 8	17e8	In Roon	4ab5
Dirac Off	3fc0			In Bluetooth	46b9
				In USB	2dd2
				In AES	5ba4

Color Buttons and A-D / Preset Buttons¶

The remote's color buttons run fixed system functions:

Button	NEC Code	Command
Red	51ae	Toggle debug menu on front panel
Green	52ad	Show playback settings on front panel
Yellow	53ac	Reload front panel
Blue	54ab	Reset HDMI

The A–D buttons (55aa, 56a9, 57a8, 58a7) and Preset 1–4 buttons (03fc, 04fb, 05fa, 06f9) are freely assignable from the Macros page. Macros can record multiple setting changes so a single button plays them all back in sequence. Macros beyond these 8 remote slots — Additional Macros — can be added to the Home page from Personalize, but they are not reachable by remote or IR code.

Additional Codes for Automation¶

The 16 codes below aren't printed on the remote, but they work over the HTTP control gateway described below, which makes them useful for macros and third-party automation:

Function	NEC Code	Function	NEC Code
Tone control on/off	708f	Dirac Live filter slot 1	7887
PEQ on/off	718e	Dirac Live filter slot 2	7986
Tone control Bass +1	728d	Dirac Live filter slot 3	7a85
Tone control Bass -1	738c	Dirac Live filter slot 4	7b84
Tone control Treble +1	748b	Dirac Live filter slot 5	7c83
Tone control Treble -1	758a	Dirac Live filter slot 6	7d82
Lipsync +1	7689	Loudness level +1	7e81
Lipsync -1	7788	Loudness level -1	7f80

Note

The Dirac Live filter slot codes select filter slots 1 through 6 (internally slots 0 through 5). A code for a slot beyond how many your unit has calibrated does nothing.

The Seat Shaker, Bass EQ, Channel Levels, Demo Mode, and other features added since 2021 don't have their own IR codes — control them through a macro instead.

HTTP Control¶

An IR-code-over-HTTP gateway lets you send the codes above using plain HTTP requests, for remote control and automation of the HTP-1. All IR codes except Power Off and Power On are confirmed supported.

The URL for the gateway is:

http://<your-htp1-ip>/ircmd?code=XXXX

where XXXX is the NEC code from the tables above. More than one code may be sent by separating them with commas. Each code must be sent exactly as shown — 4 lower-case characters. The examples below use wget and curl:

Selects HDMI 1, Native upmix mode, unmute:

wget "http://<your-htp1-ip>/ircmd?code=0ff0,1ee1,4cb3"
curl "http://<your-htp1-ip>/ircmd?code=0ff0,1ee1,4cb3"

Selects HDMI 2, Direct upmix mode, mute:

wget "http://<your-htp1-ip>/ircmd?code=10ef,4bb4,1be4"
curl "http://<your-htp1-ip>/ircmd?code=10ef,4bb4,1be4"

Sets the upmixer to None and activates Dirac Live filter slot 1:

wget "http://<your-htp1-ip>/ircmd?code=1be4,7887"
curl "http://<your-htp1-ip>/ircmd?code=1be4,7887"

The gateway can also be used directly from a web browser's address bar. For example, this URL toggles PEQ on and off: http://<your-htp1-ip>/ircmd?code=718e

Every request returns the full system status as JSON. This is an advanced feature intended for automation and control; some properties in the response are internal and undocumented, and can be ignored. See Integrations and Control for more on driving the HTP-1 from a home automation system, and the Developers section of this site for the full control protocol used by the web UI itself.

Warning

/ircmd has no authentication. The HTP-1 is designed to sit inside your home network — do not expose it directly to the internet.

Web UI page addresses are hash-mode, for example http://<your-htp1-ip>/#/settings/speakers.

Custom Presets, Macros, and Bass EQ¶

Owners have historically built their own tools around the HTP-1's controls — preset editors, enhanced PEQ editors, and BEQ filter management. Those capabilities now ship as built-in pages: use Macros to record and assign actions to the remote's buttons, and Bass EQ to apply community-maintained BEQ filters to your subwoofers.

Glossary¶

Term	Meaning
RC	Dirac Live Room Correction — the base Dirac Live filter type; does not manage bass, so the HTP-1's own bass manager stays active.
BM	Dirac Live Bass Management — a Dirac Live filter type that combines room correction with Dirac Live's own bass management for seamless integration of speakers and subwoofers.
BC	Dirac Live Bass Control — an earlier Dirac Live filter type that adds advanced bass management. Superseded by ART for new calibrations, but still fully supported.
ART	Dirac Live Active Room Treatment — Dirac's most advanced filter type. It manages bass across all capable speakers and subwoofers, and locks PEQ placement, speaker delay, and speaker trim.
Channel Signal	The decoded audio stream for one audio channel before bass management and other speaker-specific processing.
Speaker Signal	The final processed signal sent to one physical loudspeaker after bass management, delay, trim, and other speaker-specific processing.
LFE	Low-Frequency Effects — the dedicated bass channel carried in surround formats, normally routed to the subwoofer(s) by bass management.
Crossover	The frequency at which bass is redirected from a speaker to the subwoofer(s) during bass management.
Upmixer	A process that expands a stereo or lower-channel-count signal to fill more of your speaker layout, for example Dolby Surround or Auro-Matic.
dBFS	Decibels relative to Full Scale — a digital level measurement where 0 dBFS is the loudest a signal can be before clipping.
Headroom	The margin between the digital signal level and 0 dBFS, where clipping occurs.
Zero Point	Offsets the displayed master volume reading without changing the actual playback level or internal master volume.
eARC	Enhanced Audio Return Channel — the HDMI connection that carries audio back from your display to the HTP-1, supporting higher-bandwidth formats than the original ARC.