Monoprice HTP-1 Home Theater Processor Review

[stunta]

Do you use the high pass crossover in the plate sub amp for each of the mains or an external crossover?

external. Minidsp 8 channel with Dirac

 

[rhollan]

So, a DDRC-88A? I use a nanoAVR HD and a nanoAVR DL on HDMI signals, then an SDI02 and an AES deembedder to drive an old Lucid 8824 8 channel DAC.

 

[Spocko]

I have been following this thread as I am looking to add Atmos to my theater.

My system is currently 7.1, but rather odd: I take an HDMI signal, convert it to SDI with an SDI02, that conveniently strips HDCP. From SDI, I can extract four sets of two channel AES/EBU digital audio at up to 24 bit, 48 kHz sampling rate. With this, I can run through a MiniDSP DDRC-88D (or a pair of nanoAVRs prior to conversion to SDI), and then the DAC and speakers of my choice.

Right now I am using a 0.005% THD Symmetrix Lucid DAC8 Dac (85 dB SINAD), and a set of Crown (75 dB SINAD) and Outlaw audio amps. Despite the poor numbers, it sounds amazing. But, the more important thing is that I can substitute any DAC (and amps) that I want. A unified preamp/processor without digital outputs (The Storm 32d.32 AES edition has them, with Dirac Live, at an eye-watering US$16k or so) limits me to whatever SINAD I can get out of it's DACs (and associated circuitry). The Monoprice HTP-1 with better than 100 dB SINAD at 2 Volts for $4000 is a steal compared to anything else. It truely is an example of engineering being the Art of Compromise.

Would I love to have seen great figures at 4V? Sure. Are commensurate amps that insensitive? No. Can you drive them to full power with the output of the HTP-1 without going into excessive distortion? Yes. Thermal noise justifying a high level signal starts to matter when you seek to reach 110 to 120 dB SINAD.

Comparing a pre/pro like the Emotiva RMC-1, with slightly better measurements, but continued bugginess is a no brainer: the HTP-1 wins on stability without giving up too much in the way of performance (and adds in the way of functionality with eARC). Can we do better? If I seek to continue my design with an alternate 7.1 non-Atmos path, I'm left going to Okto DAC 8s (US$1200) and some type of switch ($1000 will get you a Broadcast Devices 8 channel relay switch, with about 105-110 dB noise (from control components)). But while the Okto DAC8 beats this, if you want a convenient switch between 7.1 and Atmos, you're now paying $2000 extra (plus the cost of existing processing nanoAVRs or a DDRC-88D and SDI to AES deembedders, at $1500 to $2000) FOR THE SAME QUALITY YOU'RE ALREADY GETTING OUT OF THE HTP-1 with a lot more complexity. You can have 7.1 118 dB SINAD if you don't want to switch between that and Atmos, but the minute you do, the switch will trip you up. So, you consider eliminating a mechanical switch and, damn it, brute-forcing ADCing the output of the HTP-1, switching digitally, and then running everything, except perhaps Atmos height signals, through something like Okto DACs. Actually, a Lynx Aurora 8 would be up to the job, being about as good as the HTP-1, and can be had for around $700 used. You still need the DAC (As the Aurora is about as good as the HTP-1 on the ADC/DAC sides), so $1200 there. You can't win unless you get something like a Storm Audio pre/pro, the 32 channel AES upgrade package (because it's DACs are WORSE than those in the HTP-1) AND a decent DAC like an Octo DAC8. You're looking in the neighborhood of US$17k.

So, from my perspective, the Monoprice HTP-1 is the best value for dollar. Doing better will require you to either give up stability (Emotiva), or spend at least four times as much (Storm Audio). I am not willing to pay around $1000/dB for 12 dB better SINAD figures. Your mileage may vary, but I think an HTP-1 is in my future.

One very nice feature the Storm Audio pre/pro has, that I wish the HTP-1 did, is the ability to run multiple active left, center, and right speakers. This is useful if you want to have dedicated stereo subwoofers just for the left and right channels, crossed over a bit higher than 80 Hz (say 120), so they are localizable. One can use the subwoofer high-pass outputs, of course, but it is not clear how good their quality is. (I'm looking at you: Rythmic XLR2 plate amp.)

You mentioned dedicated stereo subwoofers and I couldn't help but link this Audioholics article about the compromises inherent in stereo subs - I thought it was very well researched: https://www.audioholics.com/room-acoustics/stereo-bass

 

[rhollan]

You mentioned dedicated stereo subwoofers and I couldn't help but link this Audioholics article about the compromises inherent in stereo subs - I thought it was very well researched: https://www.audioholics.com/room-acoustics/stereo-bass

An interesting article, thanks.

I currently run dual mono subs across the front wall at 1/3 and 2/3 positions and get excellent, even bass response. Mains (BG Radia 520i and 220 dx) are crossed over at 80 Hz and in-wall (BG Radia PD6-LCRi) surrounds at 50 Hz. If this is surprising, those are the 6dB points for all speakers: the surrounds actually have slightly larger woofers than the mains.

I was considering moving the existing subs to a similar position along the rear wall, for mono bass, and augmenting with stereo subs in the front, crossed over at between 160 and 200 Hz, to get the best of both worlds, and effectively running the fronts full range, particularly for music. Then again I might stick with mono bass in the front and just upgrade the subs.

 

[stunta]

So I couldn't resist and ended up buying the HTP-1. First time I've bought something that has had a negative review from Amir; I am going to burn in hell.

I just read through so many posts and my head is spinning. My LCR are active JBL 708Ps and the manual says this:

The speaker includes software-selectable +4 dBU Input sensitivity for connection of high-output professional equipment and -10 dBV input sensitivity that provides additional gain for products with consumer-level signal output.

What should I set on the JBL and what max output voltage should I set on the HTP-1?

 

[rhollan]

+4 dBu is about 2V, just above the low distortion limit of the preamp. I would select -10 dBV for short interconnect runs and only select the higher lever for ling ines if nouse is an issue. Set the output level on tbe HTP-1 appropriately. Honestly, at 2V you are probably fine at the higher level. I would not go higher on the preamp as it distorts badly above that.

 

[stunta]

+4 dBu is about 2V, just above the low distortion limit of the preamp. I would select -10 dBV for short interconnect runs and only select the higher lever for ling ines if nouse is an issue. Set the output level on tbe HTP-1 appropriately. Honestly, at 2V you are probably fine at the higher level. I would not go higher on the preamp as it distorts badly above that.

Thanks. My XLR cables are 50' runs, so pretty long. Not sure why this didn't occur to me earlier, but I found an online converter and it says the following:

The home recording level (consumer audio) of −10 dBV means 0.3162 volts, that is −7.78 dBu.
The studio recording level (pro audio) of +4 dBu means a voltage of 1.228 volts.

http://www.sengpielaudio.com/calculator-db-volt.htm

 

[MakeMineVinyl]

Thanks. My XLR cables are 50' runs, so pretty long. Not sure why this didn't occur to me earlier, but I found an online converter and it says the following:

The home recording level (consumer audio) of −10 dBV means 0.3162 volts, that is −7.78 dBu.
The studio recording level (pro audio) of +4 dBu means a voltage of 1.228 volts.

http://www.sengpielaudio.com/calculator-db-volt.htm

2 volts is about +8.23dB (ref .775V) - +4 is as you said 1.228V.

 

[stunta]

So if I set my speakers to +4 dBu and the HTP-1 at 2 volts, amps in the speakers are going to clip?

 

[markus]

So if I set my speakers to +4 dBu and the HTP-1 at 2 volts, amps in the speakers are going to clip?

Probably not but why not set speakers and HTP-1 to 4dBu = 1.228Vrms and be on the safe side?

 

[audioBliss]

+4 dBu is about 2V, just above the low distortion limit of the preamp. I would select -10 dBV for short interconnect runs and only select the higher lever for ling ines if nouse is an issue. Set the output level on tbe HTP-1 appropriately. Honestly, at 2V you are probably fine at the higher level. I would not go higher on the preamp as it distorts badly above that.

How should one interpret the numbers? Looking at SINAD it would seem that even at 2.7V output it has 103dB SINAD but looking at the THD+N it looks worse. Why is that and looking at the SINAD only it would seem that closer to 3V out would be acceptable.

 

[rhollan]

D'Oh! I used dB power (divide by 10) instead of dB voltage (divide by 20 because power is V*V/R) My bad. +4 dBu is 1.228V. This is perfectly fine for the HTP-1 to output. You should set this as the max output level on the HTP-1 and the input sensitivity (input level to achieve max output) on the active speakers.

Generally, you want to use the highest output level from the preamp that does not distort and attenuate it at the amp to meet the amp sensitivity levels to combat thermal noise in the amp input stage and interference picked up on the interconnect (already combatted with a balanced line). This is called gain staging.

Now, one thing that is confusing is that -10dBV and +4dBu are generally NOMINAL levels in (consumer and professional, respectively) audio, with up to 20 dB headroom. Is the input setting on your active speaker for NOMINAL signal level or maximum level to reach peak output (sensitivity)? Usually it is the sensitivity (at least for professional amps). You want to match max output on your preamp with sensitivity on your power amp (or, in your case, active speakers).

Consumer gear tends to be rated on nominal levels (-10 dBV) but pro gear on peak levels with a +4 dBu nominal level. This is why you might see a max output rating on a consumer preamp of, say 8V. And yes, your pro DAC might put out +24dBu peak at 0 dBFS (dB full scale): +4 dBu with 20 dB headroom. That's 12.28V! Professional amps typically have input sensitvities of .774 or 1.54V and INPUT ATTENUATORS to pad the input down. "Pro-sumer" gear, not so much. So, check that the +4 dBu setting on your active speaker is a sensitivity, not nominal, setting.

As for the difference between dBV and dBu: dBu (decibel unit power) stems from the older dBm (decibel milliwatt into 600 ohms) -- 0dBm being the voltage required to dissipate 1 milliwatt in a 600 ohm load. From Ohm's law: .001 = V*V / 600 so V= 0.7746. These days input impedences vary (and are usually much higher than 600 ohms) but that voltage stuck as a 0 dB reference and is the same for 0 dBu.

So, what is dBV? Simply a voltage level relative to 1 volt. 0 dBV is 1 volt, and -10 dBV is sqrt(0.1) volt. -10 dBV = 20 log (sqrt(.1)/sqrt(.6)) = -7.78 dBu.

 

[rhollan]

How should one interpret the numbers? Looking at SINAD it would seem that even at 2.7V output it has 103dB SINAD but looking at the THD+N it looks worse. Why is that and looking at the SINAD only it would seem that closer to 3V out would be acceptable.

Distortion generally rises with output level as does signal to noise. So, you want the highest output level to not overload the amp that does not distort. This may be limited by your amp if it does not have a variable input attenuator. You might have to suffer a bit of S/N degradation to not overload your amp. But really, the difference between 1.228V and 3V is only 7.76 dB.

 

[audioBliss]

Distortion generally rises with output level as does signal to noise. So, you want the highest output level to not overload the amp that does not distort. This may be limited by your amp if it does not have a variable input attenuator. You might have to suffer a bit of S/N degradation to not overload your amp. But really, the difference between 1.228V and 3V is only 7.76 dB.

What I've found a bit tricky with the HTP-1 is that after Dirac has been run and all speaker levels have been set you pretty much have to go to over 0dB on the main volume control to reach reference levels. For instance the nc400 monoblocks should produce 400W (4Ohm) at 2.2V but setting the output level of the HTP-1 to 2.2V and with a volume of 0dB I am no where near reference levels and I assume no where near 2.2V since in theory 400W would give me way past reference levels.

Seeing that there seemed to be an issue with going over 0dB on the volume control I've resorted to using 2.9V(I choose this because it seems to be the max input for nc400 where 2.2V is max RMS...not sure what that means tbh but I take it 2.9 is for max burst) which I still think doesn't give me reference levels at 0dB on MV but loud enough for even most soft content. Very tricky to know exactly what voltage it's sending out at 0dB on the main volume control.

I can however set it to 2.2V output level and then go beyond 0dB on the volume control and get reference levels but as I understand it is not recommended to go beyond 0dB on MV.

 

[TimoJ]

What I've found a bit tricky with the HTP-1 is that after Dirac has been run and all speaker levels have been set you pretty much have to go to over 0dB on the main volume control to reach reference levels. For instance the nc400 monoblocks should produce 400W (4Ohm) at 2.2V but setting the output level of the HTP-1 to 2.2V and with a volume of 0dB I am no where near reference levels and I assume no where near 2.2V since in theory 400W would give me way past reference levels.

Seeing that there seemed to be an issue with going over 0dB on the volume control I've resorted to using 2.9V(I choose this because it seems to be the max input for nc400 where 2.2V is max RMS...not sure what that means tbh but I take it 2.9 is for max burst) which I still think doesn't give me reference levels at 0dB on MV but loud enough for even most soft content. Very tricky to know exactly what voltage it's sending out at 0dB on the main volume control.

I can however set it to 2.2V output level and then go beyond 0dB on the volume control and get reference levels but as I understand it is not recommended to go beyond 0dB on MV.

Does Dirac reduce main L/R trim levels? It shouldn't if your other channels are gain/level matched correctly.

 

[rhollan]

If the sensitivity on the amp is 2.2V RMS that is going to be 2.2 * sqrt(2) or 3.11V peak. Is it possible the output level on the HPT-1 is peak and not RMS?

 

[TimoJ]

If the sensitivity on the amp is 2.2V RMS that is going to be 2.2 * sqrt(2) or 3.11V peak. Is it possible the output level on the HPT-1 is peak and not RMS?

It's RMS.

 

[markus]

What I've found a bit tricky with the HTP-1 is that after Dirac has been run and all speaker levels have been set you pretty much have to go to over 0dB on the main volume control to reach reference levels. For instance the nc400 monoblocks should produce 400W (4Ohm) at 2.2V but setting the output level of the HTP-1 to 2.2V and with a volume of 0dB I am no where near reference levels and I assume no where near 2.2V since in theory 400W would give me way past reference levels.

Seeing that there seemed to be an issue with going over 0dB on the volume control I've resorted to using 2.9V(I choose this because it seems to be the max input for nc400 where 2.2V is max RMS...not sure what that means tbh but I take it 2.9 is for max burst) which I still think doesn't give me reference levels at 0dB on MV but loud enough for even most soft content. Very tricky to know exactly what voltage it's sending out at 0dB on the main volume control.

I can however set it to 2.2V output level and then go beyond 0dB on the volume control and get reference levels but as I understand it is not recommended to go beyond 0dB on MV.

Are you connecting to the amp balanced or unbalanced? You would need to double the voltage setting in the HTP-1 for unbalanced.

 

[audioBliss]

Does Dirac reduce main L/R trim levels? It shouldn't if your other channels are gain/level matched correctly.

Why should Dirac not reduce trim levels? Dirac will always do this unless you have the same speakers at the same distances and amplifiers with adjustable gain. In my case it uses the most quiet speaker which is the center channel as trim 0 and the reduces the levels of all other speakers around that. Nothing weird about that imo.

Are you connecting to the amp balanced or unbalanced? You would need to double the voltage setting in the HTP-1 for unbalanced.

Balanced.

 

[stunta]

@MonolithGuy Can you please add your recommendations on the max output voltage setting? Thanks.