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Monoprice HTP-1 Home Theater Processor Review

amirm

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#1
This is a review and detailed measurements of the Monolith Monoprice HTP-1 16-channel AV Processor. A kind member ordered it and had it drop shipped to me. The HTP-1 has recently started shipping and costs US $4,000 from the company direct.

I can't say I am a fan of the industry design of the HTP-1 but do like the large display:

Monolith by Monoprice HTP-1 16-Channel Home Theater Processor Review.jpg

The packaging feels cheep for a product in this price category. Back panel seems too think and I could flex the IEC input jack in and out as I plugged in my cable.

The rotary encoder is too shallow for proper grip and has no acceleration support. So you better not be in a hurry when you try to make big volume changes. You can crank it hard and watch the lazy volume indicator gradually change. On the other hand, minor changes are hard to do due to coarse resolution of 1 dB and jittery encoder that jumps 2 dB when you want to change 1 dB.

Cold boot takes a long time. After that, it stays in some kind of suspended mode and wakes up quickly until it loses power. Then the slow cycle starts again.

I set the options to show details of audio formats and such but I still did not seem the same rate and bit depth on the display. There is so much real estate there and the webserver can show it so why not on the LCD?

Love the back connectors in the way it dismisses the ancient composite and component video connectors and just gives you what you need on a modern AV product:

Monolith by Monoprice HTP-1 16-Channel Home Theater Processor Back Panel Connectors Inputs and...jpg

Note that there is no on-screen display. You manage the unit through its app or web server. I used the latter which worked very well on the desktop. On my Samsung S8+ the pop up was slow and there was some refresh bugs. On the desktop, it was far superior to any on-screen display.

I started my testing using the AES/EBU digital input. I then switched to testing with HDMI but no luck. The unit would simply not pass video from my PC's Nvidia graphs card. I would get a blank screen. I set the resolution to 1080p and it still produced no picture. So I dragged the unit to my main system, rip it apart :(, and tested it there. It worked fine with my Samsung UHD player and LG OLED TV. I have tested countless AVRs and processors with PCs and while they don't always work perfectly, they do produce a picture. I am worried about level of compatibility of HTP-1 given my experience.

FYI I did a system upgrade and it made no difference (it reports version 1.1 on display when it boots).

Overall this is a mixed bag of very nice display and web interface, and not so good input control and sheet metal. Not a showstopper though if the performance is there.

AV Processor DAC Performance
As noted, I used AES/EBU balanced digital input to feed the HTP-1. Here is the outcome at nominal 4 volts that desktop DACs produce:

Monolith by Monoprice HTP-1 16-Channel Home Theater Processor 4 Volt Audio Measurements.png


OK, not broken but not that great either. Reducing the level to 2.7 volts which is the max that some other processors/AVRs produce before clipping gave a bit better performance:

Monolith by Monoprice HTP-1 16-Channel Home Theater Processor 2.7 Volt Audio Measurements.png


Note that you get severe clipping at 4.5 volts or so. And that messing with the amplifier sensitivity level in the setup does not help with any of this. Anyway, this is where the ranking lands with the two output settings:

Best Home Theater Processor Surround Video Measurements.png


With the lower output, I think we have our first AV product that breaks into the green category. Among AVRs, that also edges out all other AV products we have tested:

Best Home Theater Processor Performance Review 2020.png


Dynamic range was good:

Monolith by Monoprice HTP-1 16-Channel Home Theater Processor 4 volt dynamic range Audio Measu...png


As was multitone performance:

Monolith by Monoprice HTP-1 16-Channel Home Theater Processor 4 Volt Multitone Audio Measureme...png


Wideband distortion and noise was not that competitive though:
Monolith by Monoprice HTP-1 16-Channel Home Theater Processor THD+N vs Frequency Distortion Au...png


Intermodulation distortion versus input level shows that we still have not closed the gap with even budget desktop DACs:

Monolith by Monoprice HTP-1 16-Channel Home Theater Processor 4 Volt IMD distortion Audio Meas...png


Frequency response was fine:
Monolith by Monoprice HTP-1 16-Channel Home Theater Processor 2.7 Volt Frequency Response Audi...png


Filter response is the typical default in DAC chips:
Monolith by Monoprice HTP-1 16-Channel Home Theater Processor 4 Volt Filter Audio Measurements.png


What is that? You don't know why it get the decapitated panther with this type of performance? Well, this is why:

Monolith by Monoprice HTP-1 16-Channel Home Theater Processor 4 Volt Linearity Audio Measureme...png


The test starts at -120 dB and keeps increasing the level. The HTP-1 kept flashing its PCM indicator but would produce no output until we got down to -90 dB which is 1 bit short of 16 bit audio. We can see this clearly by looking at the waveform at -90 and -96 dB:

Monolith by Monoprice HTP-1 16-Channel Home Theater Processor 96 dB bug Audio Measurements.png


As you see in the inset, I am definitely sending it 24 bit audio.

We saw this behavior in another processor, namely the Emotiva XMC-1:



Seems like the same shop that supplied the audio subsystem for XMC-1 is behind the same mistaken design in HTP-1. We could forgive the XMC-1 for being old but no such excuse holds for HTP-1. Folks, this is ABCs of design. You verify simple things like whether the device can process 24-bit data. After all, almost all video soundtracks are 24 bits.

EDIT: There is a setting in the menu to override the low level muting. The output clips though. See: https://www.audiosciencereview.com/...me-theater-processor-review.11416/post-326504

Jitter was another disappointment:

Monolith by Monoprice HTP-1 16-Channel Home Theater Processor Jitter bug Audio Measurements.png


Wish I could test HDMI but can not. Above spikes are correlated with the 250 Hz square wave that is embedded in J-test signal. This means what bits to feed the DAC changes its analog input! So bits are not bits unfortunately. Fortunately levels are low so likely not audible but in a high-end processor, we better not see artifacts like this.

Conclusions
The HTP-1 seems to want to raise the bar on DAC performance over its competitors and it succeeds a bit there. But then it truncates every 24 bit sample to 16 bits, removing the value of such performance. Jitter performance is also not good. And of course, if you can't get video through the thing as was my experience with my PC, then the rest does not happen.

I am hoping that the muting problem beyond 15 bits can be fixed with a firmware update. If so, and the video compatibility is not a broader issue, I would give HTP-1 a passing grade. As it is now, it is not ready for production.

EDIT: an obscure setting fixes the linearity/muting issue. This setting should be the default, not the other way around. I am still bothered by lack luster output level and distortion for a $4,000 product. So not changing my recommendation. Buy this product because you want its features, not because you think the $4,000 is bringing you superlative objective audio performance. There are $150 stereo DACs that easily outperform it on that front.

------------
As always, questions, comments, recommendations, etc. are welcome.

This is my second review for the day. I now you can be cheap but even you can feel sorry for me by donating money using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
 
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Tks

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#3
I was looking at the review, it felt like a story.

Thinking at first, wait, lower power performs better? That's wonderful because everything these days feels like overkill for me in the power department. I see also it's in the green category, as I go on, I think the bossman dun lost his mind.

Then I see the linearity metric. And then get another slap on the cheek with the jitter.

Come on Monoprice, for $4,000 I know you could've done better :-|
 

Sancus

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#4
Wow, how did Monoprice let it out the door with that 24-bit audio bug when AVRs that cost less than 1/4 of this don't have any such issue? Clearly it wasn't tested...

I sure hope they can fix it with a firmware update because that's unacceptable for $4000.
 

spacevector

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#5
Does the unit come with a remote?

When volume is changed, does it show on TV display?

What's a few uV among friends?

Funny I was browsing this product yesterday and thought whether it will feature on ASR soon.

Thanks to Amir for the review and congrats to the member on the new toy. Seems a nice enough piece to me albeit not without early adopter pains.
 
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LTig

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#6
Can we be sure that the linearity cutoff is a real world problem? I think we see just a gating behaviour which shuts off in case of "no" signal, and in the presence of signals above the -90 dBFS the cutoff would not be done.

@amirm could you measure a dual tone with a 10 kHz @ -84 dBFS and 1 kHz @ -120 .. -84 dBFS? If all the 1 kHz signals are seen I'd say the cutoff has no relevance to real world usage.
 
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Sancus

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#10
It’s the only option other than paying 5 figures for Trinnov.
Well, the JBL SDP-55 might exist one day, who knows. Release seems like it keeps being pushed back. $6K is not an easy pill to swallow, either, but still a bargain compared to ridiculous Trinnov stuff.
 

audioBliss

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#11
I very much appreciate the AVR reviews. Thank you to the people sending them in and Amir for doing the tests! I feel like Monoprice did a descent effort here but again for the price it is not acceptable. So far there are no AVRs that have passed with flying colors. Monoprice is a new player in the market so pretty descent effort considering. But damn the one company that gets a passing grade everybody in the enthusiast community is going to buy it. There is a huge opportunity here. I hope manufacturers are reading this. Hire some QAs to test these products before launch. It will save you in the long run!! The word will spread in the community you can be sure of it.
 

Costas EAR

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#12
Could it be that the HTP-1 is truncating in order to prepare for handing off to Dirac processing? Dirac is limited to 16 bit AFAIK.
I suppose so.
After all, dirac makes the difference, especially in a complex multichannel setup.

IMHO: For the price range, HTP-1 seems a bargain, considering the performance of the expensive NAD.

One question: is it roon ready?
Trinnov is roon ready.
 

astr0b0y

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#13
I suppose so.
After all, dirac makes the difference, especially in a complex multichannel setup.

IMHO: For the price range, HTP-1 seems a bargain, considering the performance of the expensive NAD.

One question: is it roon ready?
Trinnov is roon ready.
Yes, works as Roon endpoint but doesn’t yet have official Roon Ready support. It’s in for testing with Roon.
 

Dimifoot

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#14
The test starts at -120 dB and keeps increasing the level. The HTP-1 kept flashing its PCM indicator but would produce no output until we got down to -90 dB which is 1 bit short of 16 bit audio.
I was under the impression that this issue was clarified by the Emotiva guys in the XMC review, and its a measurement-related finding, not applicable in real world situations, (as explained here again):
Can we be sure that the linearity cutoff is a real world problem? I think we see just a gating behaviour which shuts off in case of "no" signal, and in the presence of signals above the -90 dBFS the cutoff would not be done.
One question: is it roon ready?
Yes, but no multichannel Roon
 

milosz

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#15
For the performance offered this thing is too expensive, even assuming the -90 dB thing is some kind of intended muting function when the unit thinks no signal is present.
 

miero

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#16
But then it truncates every 24 bit sample to 16 bits, removing the value of such performance.
I miss a proof that samples are truncated to 16 bits. Measurement just shows that an auto-mute triggers when there is no signal in upper 15 bits.
 
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Gedeon

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#17
I'm starting to think that in order to have "headroom" when using room-eq technologies, some builders cut to 16bits in an early stage. So a bunch of available bits is recovered (let's say 8) to apply corrections without clipping and finally sending 24-32bits to the internal DAC.

But just a guess, maybe I'm totally wrong.
 

audioBliss

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#18
I was under the impression that this issue was clarified by the Emotiva guys in the XMC review, and its a measurement-related finding, not applicable in real world situations, (as explained here again):
I think it is very important to get to the bottom of this behaviour. What are the real world impacts and does this happen with real world signals. Is this even an issue or is Amir miss-interpreting some part of their implementation?
 

BDWoody

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#19
Well, the JBL SDP-55 might exist one day, who knows. Release seems like it keeps being pushed back. $6K is not an easy pill to swallow, either, but still a bargain compared to ridiculous Trinnov stuff.
I think I'll be waiting for that one...it's not THAT far into the future...we keep hearing...

Is this the same Sancus that posted the review over on the AVS owners thread? It'll be interesting to see the responses.

For now, I will be asking Amir to pack it up for a return... I had hoped it would be a little closer to a finished product, and for $4k I don't want to see these kinds of compromises. Maybe I'm being unrealistic, but that's ok...I can wait.
 

Dimifoot

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#20
I think it is very important to get to the bottom of this behaviour. What are the real world impacts and does this happen with real world signals. Is this even an issue or is Amir miss-interpreting some part of their implementation?
I am not an engineer, so I can't expain it thorougly.
I do remember the manufacturers response in the XMC thread: it doesn't apply to real world signals, only in measurement situations.
For the performance offered this thing is too expensive
We should keep in mind that this is not a 2 channel dac.

Its 16 channels, not two, + dsp-crossover functions+ expensive room eq software (7.1 Dirac software for PC used to cost 700 euros)+ HDMI-dolby-dts etc codecs/royalties etc etc.

I consider it a bargain, and definitely measures better than any AV product tested here. 10db better SINAD than the Marantz 8805, which is more expensive, 6 db better than the NAD (also more expensive).

Comparison with the 2 channel equipment is not easy. There are some 2 channel dac- processors with good Room eq software and subwoofer cross functions from NAD, minidsp, Lyngdorf, Trinnov, and they definitely cost a lot more than 1000 euros. For 2 channels. No codecs/royalties included.
Lets do the math.

And most important: I would never consider buying 2 channel processors in 2020. Multichannel reproduction is way more satisfying- and accurate (!) with the appropriate recordings.

2 channel systems are so vintage :p.
 
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