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Can the HTP-1 matrix wides with Auro 3D engaged?
Yes

Does anybody know if the upcoming Dirac BMM will address the issue I'm having? I hear it's supposed to test speaker combinations.
No way to know for sure. DL BMM is focused on time-domain optimization of the subwoofer-speaker blend (individual/per-speaker). I recommend inquiring with Dirac and see what their response is.
 

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With the Audio Science review of the HTP-1, it appeared that there was a match between some unusual design decisions in what is normally very straightforward circuitry, and the ASR review results. For example, few quantitative specifications are provided by Monoprice for the HTP-1, in itself a bad omen, one clear specification, which should be trivial to meet, is maximum output of 7V. Distortion should also be lower given the overall apparent quality of the HTP-1 layout and choice of components. Unfortunately this miss in performance starts to raise doubts about of other characteristics that haven't been measured or would be very hard to measure, but that's not the subject here.

Needless to say I could be wrong, I don't have access to the schematics, and much of the performance is determined by software, and by signal level / gain design decisions. Nevertheless the in place hardware seems to play a key roll. This is unfortunate, because if it is correct, then hardware changes involving board swaps would be necessary for the product to meet the 7V specification and to achieve the potential offered by its basic design. Software (firmware) changes won't do the job by themselves. Effectively the HTP-1 can be considered broken and in need of warranty repair if it won't provide the 7V output.

It will be interesting to see what response, if any, Monoprice makes to the measured results in the ASR review and to the comments above. The Monoprice Monolith amplifiers and subs have shown that Monoprice appears to have a goal of supplying excellent performance at a reasonable price. So far the HTP-1 seems to come up short against this goal. The existing performance from what we know so far of the HTP-1 (IMO) as very good compared to typical consumer products, at a price that isn't all that low for a product sold direct. Excellence is required to justify the price. Clearly IMO the HTP-1 doesn't meet the rather high standards set by the amplifiers and subs.

o No one asked me, but that fact represents a very low barrier to offering opinions, what should Monoprice do?

- Determine if performances issues are real, that is, 7V output can't be met a low THD+N, and THD+N is higher than need be at say 3V and up.

- If the issues are real, then fix them with software changes if possible.

- If hardware changes are required, let's say a redesign of the DAC to output board, then update the board.

- Ship new units with the upgraded board.

- Offer some combination of remediation of the problem for existing owners (conflict of interest here, I'm one of those owners so I'm suggesting steps that would benefit me.) This could be:

o Offer to swap boards when the board is available.

o Extend the return/trial period for all owners.


What is the opinion of other owners?
What is the sensitivity of your amplifiers?

There do appear to be some disconnects regarding the initial HTP-1 target metrics from the interview with Audioholics ("The max unclipped output is 24dBu (12Vrms)"), the user interface (7Vrms), and reality (~4Vrms). I spoke to several of the design engineers and there is not a problem with the volume control, it is working exactly as designed. They researched the sensitivities of the majority of amplifiers on the market to determine the voltage range to optimize. There definitely needs to be much more clarification for how it operates and why. It is a unique implementation (I appreciate the time spent with me revealing the details of the implementation). In regards to S/N and SINAD/THD+N, I suspect the HTP-1 outperforms everything else in the market from 0-2.5V. The performance over the entire range is far more important than just at 4V. The metrics at 4V are still quite good. An Amplifier Sensitivity/Volume Control white paper was suggested and I expect one soon. It is possible to increase the output by changing the volume control algorithm, but it would come at the cost of performance that I don't think would benefit any users.

I am withholding some of my measurements to give me the opportunity to review the results with Trinnov and Bryston/StormAudio. and Acurus. The poor measurement of StormAudio base 16 channels was somewhat known already. The XLR-4 module was an improvement. I suspect the Storm mk2 hardware will be much better. My understanding is that there are mk2 option module blades as well and the mk1 boards will not be supported in the mk2. I don't know whether or not the mk2 boards will be supported in the mk1 and updated mk1.5 units.
 

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I have one amp with 1.6V and one with 3.3V. I have my Amp Sensitivity set to 3.2V. LCR and Subs run off of the 1.6V amp (Monolith), but they've been trimmed down about 15dB (by Dirac). Surrounds run off the 3.3V amps (ICEpower), and they're not trimmed down. LCR and Subs are 4ohm, and the Surrounds are all 8ohm.

Rick
Rick, what volume level do you typically listen to? Is there a max level that you do not exceed? If so, we could optimize further. If you use 0dB (or higher on material mastered at low levels) you are close to optimized. Just increase it to 3.3V. There is a tiny bit of headroom built in to stay just below the Amp Sensitivity level set when at 0dB volume.
 

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What is the sensitivity of your amplifiers?

There do appear to be some disconnects regarding the initial HTP-1 target metrics from the interview with Audioholics ("The max unclipped output is 24dBu (12Vrms)"), the user interface (7Vrms), and reality (~4Vrms). I spoke to several of the design engineers and there is not a problem with the volume control, it is working exactly as designed. They researched the sensitivities of the majority of amplifiers on the market to determine the voltage range to optimize. There definitely needs to be much more clarification for how it operates and why. It is a unique implementation (I appreciate the time spent with me revealing the details of the implementation). In regards to S/N and SINAD/THD+N, I suspect the HTP-1 outperforms everything else in the market from 0-2.5V. The performance over the entire range is far more important than just at 4V. The metrics at 4V are still quite good. An Amplifier Sensitivity/Volume Control white paper was suggested and I expect one soon. It is possible to increase the output by changing the volume control algorithm, but it would come at the cost of performance that I don't think would benefit any users.

I am withholding some of my measurements to give me the opportunity to review the results with Trinnov and Bryston/StormAudio. and Acurus. The poor measurement of StormAudio base 16 channels was somewhat known already. The XLR-4 module was an improvement. I suspect the Storm mk2 hardware will be much better. My understanding is that there are mk2 option module blades as well and the mk1 boards will not be supported in the mk2. I don't know whether or not the mk2 boards will be supported in the mk1 and updated mk1.5 units.
P.S. A mistake was made when the Amp Sensitivity range allowed up to 7V in the user interface. The limit should have always been 4. Going above 4 has no effect. The range will be capped at 4 in the next release.
 

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The performance of the preamp functions of Denon, Marantz, NAD, Yamaha, etc. could all be greatly improved by better physically layout of the products, use of higher rail voltages for opamps, and some improvement in component selection. These changes would result in some one time expenditures, but the much more modern layouts and production processes that would be implemented would add little to ongoing production costs. To engineers in the AV business these changes are likely rather obvious and straightforward to implement, but they have been of little interest to the management/owners.

The chief goal of sites like Audio Science is to use objective measurements to drive improvements in the industry. The AV industry been allowed to avoid measurements of their equipment by third parties and typically don't provide such measurements themselves. The businesses that provide the steady stream of subjective reviews, with few or no measurements are essentially co-conspirators if you will. Customers who have accepted marginal performance year after year also are enablers.

One of my posts in the last couple weeks in this thread provided insight into the physically layout and component selection of the HTP-1. While there are clearly limits to what can be determined from just examining a product, no matter how closely, my opinion was and is, that the physical layout and component selection of the HTP-1 represents an excellent, modern design with great potential. A clear step up from the designs the larger players such as Denon/Marantz/Yamaha that are far out of date IMO.

There is nothing in the design that the big players couldn't incorporate in their designs if they were motivated to do so, it's just good blocking and tackling. Such changes would represent a complete change in direction however. The design of the DAC to volume control to output buffers seemed let's say odd, but without measurements, was it was hard to comment.

With the Audio Science review of the HTP-1, it appeared that there was a match between some unusual design decisions in what is normally very straightforward circuitry, and the ASR review results. For example, few quantitative specifications are provided by Monoprice for the HTP-1, in itself a bad omen, one clear specification, which should be trivial to meet, is maximum output of 7V. Distortion should also be lower given the overall apparent quality of the HTP-1 layout and choice of components. Unfortunately this miss in performance starts to raise doubts about of other characteristics that haven't been measured or would be very hard to measure, but that's not the subject here.

Needless to say I could be wrong, I don't have access to the schematics, and much of the performance is determined by software, and by signal level / gain design decisions. Nevertheless the in place hardware seems to play a key roll. This is unfortunate, because if it is correct, then hardware changes involving board swaps would be necessary for the product to meet the 7V specification and to achieve the potential offered by its basic design. Software (firmware) changes won't do the job by themselves. Effectively the HTP-1 can be considered broken and in need of warranty repair if it won't provide the 7V output.

It will be interesting to see what response, if any, Monoprice makes to the measured results in the ASR review and to the comments above. The Monoprice Monolith amplifiers and subs have shown that Monoprice appears to have a goal of supplying excellent performance at a reasonable price. So far the HTP-1 seems to come up short against this goal. The existing performance from what we know so far of the HTP-1 (IMO) as very good compared to typical consumer products, at a price that isn't all that low for a product sold direct. Excellence is required to justify the price. Clearly IMO the HTP-1 doesn't meet the rather high standards set by the amplifiers and subs.

o No one asked me, but that fact represents a very low barrier to offering opinions, what should Monoprice do?

- Determine if performances issues are real, that is, 7V output can't be met a low THD+N, and THD+N is higher than need be at say 3V and up.

- If the issues are real, then fix them with software changes if possible.

- If hardware changes are required, let's say a redesign of the DAC to output board, then update the board.

- Ship new units with the upgraded board.

- Offer some combination of remediation of the problem for existing owners (conflict of interest here, I'm one of those owners so I'm suggesting steps that would benefit me.) This could be:

o Offer to swap boards when the board is available.

o Extend the return/trial period for all owners.


What is the opinion of other owners?
What is the sensitivity of your amplifiers?

For home theater and for stereo I use Benchmark AHB2's all around. Some of the AHB2's are used in two channel mode, some in bridged mode (L, R, C). These amplifiers drive a variety of Revel speakers, which need a lot of power, with Salon2's for L & R for example.

For reference, here are the measurements of the amplifiers from Stereophile. The high performance of the AHB2's is what drives the search for a really clean preamp. For reference I believe @RichB also uses these amplifiers to drive Salon2's.

https://www.stereophile.com/content/benchmark-media-systems-ahb2-power-amplifier-measurements

There is a choice of sensitivity settings. As would be expected using a higher voltage sensitivity results in better S/N performance. It would be really nice to have excellent performance at least to over 4V RMS. For quality listing in two channel, the XLR's to the L and R power amplifiers, are switched with a passive switch box. In this configuration a Benchmark DAC3 or the new RME ADI-2 FS with the AK4493 DAC IC, either of which are very clean to over 4 VRMS, drives the power amplifiers. The use of these high quality amplifiers drives my interest in having over 4V RMS of very clean output from the HTP-1, which is frankly easy to do.

Here are the sensitivity setting choices for the AHB2's for full output:

Low-Gain = 22 dBu (9.8 VRMS)
Mid-Gain = 14.2 dBu (4 VRMS)
High-Gain = 8.2 dBu (2 VRMS)

In the past I've used power amplifiers such as Bryston 4BSST2's where 4V RMS will also provide better S/N.

@Monolithguy; Marc seems to be in the middle here, but obviously is limited in what he can say, and doesn't officially represent Monoprice to my knowledge. Please respond to this email and the points raised.

I just noticed in Marc's latest post that the HTP-1 will be limited to 4V RMS output, which based on the latest measurements available will not have the low levels of THD+N that are easily obtainable. Purchase of the HTP-1 was based on the user manual, which had a 7V RMS output listed. Will the return window be adjusted for existing owners to allow for this change in specifications? It would be much better if Monoprice produced a new DAC to output board with the minor changes required to produce 7V RMS.
 

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DL BMM is focused on time-domain optimization of the subwoofer-speaker blend (individual/per-speaker).
This is the first time I've heard DL BMM described in such a way. In the classic multi-sub literature, such as Welti and Devantier's description of Sound Field Management (SFM), optimization of multiple subs is described in terms of how the subs interact with one another. In the SFM case, that's done by attempting to first minimize the mean spatial variance of the combined sub responses at each listening position, without regard to the flatness of their combined response or how they integrate with the main speakers. Then, the sub responses are equalized together to flatten them (or force them to some target curve), followed by a procedure to optimize integration of the grouped subs with each set of main speakers individually and simultaneously (subs and L/R, subs and C, subs and surrounds). But this latter integration process is outside of what's been traditionally considered optimization of multiple-subwoofer systems in the literature, because it does not require consideration of multiple subwoofers at all. The integration problem must assume that the subs be considered as a monolithic group, and so the integration of the subs with one another is not part of that problem. It's a separate one.

So it's interesting (and a bit puzzling) to see this apparent change in emphasis from multiple-sub integration, to (only?) integration of mains and subs, and posing that latter problem as a time-domain one. There hasn't been any consistent, or even coherent story from Dirac on this at all.
 

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What is the sensitivity of your amplifiers?
The high performance of the AHB2's is what drives the search for a really clean preamp. For reference I believe @RichB also uses these amplifiers to drive Salon2's.

https://www.stereophile.com/content/benchmark-media-systems-ahb2-power-amplifier-measurements

There is a choice of sensitivity settings. As would be expected using a higher voltage sensitivity results in better S/N performance. It would be really nice to have excellent performance at least to over 4V RMS. For quality listing in two channel, the XLR's to the L and R power amplifiers, are switched with a passive switch box. In this configuration a Benchmark DAC3 or the new RME ADI-2 FS with the AK4493 DAC IC, either of which are very clean to over 4 VRMS, drives the power amplifiers. The use of these high quality amplifiers drives my interest in having over 4V RMS of very clean output from the HTP-1, which is frankly easy to do.

Here are the sensitivity setting choices for the AHB2's for full output:

Low-Gain = 22 dBu (9.8 VRMS)
Mid-Gain = 14.2 dBu (4 VRMS)
High-Gain = 8.2 dBu (2 VRMS)
AHB2s and Salon2s. I am seething with jealousy! As you said, I don't represent Monoprice. @bigguyca and @RichB in your best interest, you should consider returning the HTP-1 and Emotiva XMC-2 respectively. Then putting that money towards a Lyngdorf. The Lyngdorf puts out 16 Vrms at 0dB! No one else appears to even come close.

Or, you could accept that these differences aren't audible. The HTP-1's performance is still quite good at even at 4V 3.875V.


A-weighted, I am missing the unweighted chart for this group.
 

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Here are results at 4V+




Before Trinnov owners get all up in arms, I have a call into Jon Herron to review the behavior I am observing. These above SINAD/THD+N metrics are a bit misleading. The A16 noise is rising proportionally to the signal level. The A16 outperforms the HTP-1 on other metrics likely more related to audible performance, IMD specifically.




 

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Before Trinnov owners get all up in arms, I have a call into Jon Herron to review the behavior I am observing. These above SINAD/THD+N metrics are a bit misleading. The A16 noise is rising proportionally to the signal level. The A16 outperforms the HTP-1 on other metrics likely more related to audible performance, IMD specifically.
How is the noise level measured? i.e. what volume/output settings? Could you check if switching on HTP-1's loudness and/or PEQ (with just a little bass adjustment) has any effect to those?
 

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@Marc Alexander Do you have access to a NAD 758v3 so we we have something to compare to on the other end of the price range?
 

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This is the first time I've heard DL BMM described in such a way. In the classic multi-sub literature, such as Welti and Devantier's description of Sound Field Management (SFM), optimization of multiple subs is described in terms of how the subs interact with one another. In the SFM case, that's done by attempting to first minimize the mean spatial variance of the combined sub responses at each listening position, without regard to the flatness of their combined response or how they integrate with the main speakers. Then, the sub responses are equalized together to flatten them (or force them to some target curve), followed by a procedure to optimize integration of the grouped subs with each set of main speakers individually and simultaneously (subs and L/R, subs and C, subs and surrounds). But this latter integration process is outside of what's been traditionally considered optimization of multiple-subwoofer systems in the literature, because it does not require consideration of multiple subwoofers at all. The integration problem must assume that the subs be considered as a monolithic group, and so the integration of the subs with one another is not part of that problem. It's a separate one.

So it's interesting (and a bit puzzling) to see this apparent change in emphasis from multiple-sub integration, to (only?) integration of mains and subs, and posing that latter problem as a time-domain one. There hasn't been any consistent, or even coherent story from Dirac on this at all.
How about a straightforward answer to this @flax ?
 

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How is the noise level measured? i.e. what volume/output settings? Could you check if switching on HTP-1's loudness and/or PEQ (with just a little bass adjustment) has any effect to those?
The lower numbers are the noise floor with no signal (digital input). The higher numbers are with a 0dBFS 1kHz fundamental at 0dB volume.

I will go back through and label all of the images [eventually].
 

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This is the first time I've heard DL BMM described in such a way. In the classic multi-sub literature, such as Welti and Devantier's description of Sound Field Management (SFM), optimization of multiple subs is described in terms of how the subs interact with one another. In the SFM case, that's done by attempting to first minimize the mean spatial variance of the combined sub responses at each listening position, without regard to the flatness of their combined response or how they integrate with the main speakers. Then, the sub responses are equalized together to flatten them (or force them to some target curve), followed by a procedure to optimize integration of the grouped subs with each set of main speakers individually and simultaneously (subs and L/R, subs and C, subs and surrounds). But this latter integration process is outside of what's been traditionally considered optimization of multiple-subwoofer systems in the literature, because it does not require consideration of multiple subwoofers at all. The integration problem must assume that the subs be considered as a monolithic group, and so the integration of the subs with one another is not part of that problem. It's a separate one.

So it's interesting (and a bit puzzling) to see this apparent change in emphasis from multiple-sub integration, to (only?) integration of mains and subs, and posing that latter problem as a time-domain one. There hasn't been any consistent, or even coherent story from Dirac on this at all.
Andy, I know you already know of the multiple tiers of DL BMM.

Here is my understanding: DL BMM is not Dirac's SFM/MSO solution. This would still be Dirac Unison (if it ever comes home).

The only multi-sub optimization taking place that I am aware of is the time-alignment and level matching of multiples subs. Tier 1
The subwoofers are then treated as a monolithic group and EQ's accordingly. Then each channel (pair?) is then properly time-aligned and phase-aligned (via all-pass filters) separately. Tier 2

This is why I have been hypothesizing that using your MSO software along with an external DSP and DL BMM Tier 2 will likely be the best solution for those with the ability to use/learn MSO. Tier 1 should still be a decent option for those that want a more automated solution.
 

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@andyc56 @Marc Alexander


As you know Dirac Live Bass Control in Tier 1 needs one individual channel for each subwoofer.
It will consider all subwoofers as a group and calculate filters so that all of the subwoofers work as good as possible together from a spatial variation perspective, that is, to try to reduce the variations in the bass in different positions.
After that we also consider the sub to main integration, between the set of all subwoofers and every speaker that needs to be bass managed.
As a result it will co-optimize the subwoofers so that MSO is not needed.
 

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Before Trinnov owners get all up in arms, I have a call into Jon Herron to review the behavior I am observing. These above SINAD/THD+N metrics are a bit misleading. The A16 noise is rising proportionally to the signal level. The A16 outperforms the HTP-1 on other metrics likely more related to audible performance, IMD specifically.









Any particular reason you dropped the Bryston SP4 from the list you are comparing?
 

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Dirac Live Bass Control in Tier 1 [...] will consider all subwoofers as a group and calculate filters for each subwoofer individually so that all of the subwoofers work as good as possible together from a spatial variation perspective, that is, to try to reduce the variations in the bass in different positions.
Is that what you meant?
 

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So there's no way to tell Dirac not to change the polarity of the subs. I assume Dirac thinks it needs to based on the tweeters and mids in the Zaph Audio speakers (LCR) having reversed polarity.
AFAIK, Dirac doesn't take speakers into account (doesn't even take other subs into account) when addressing subwoofer polarity. It only goes by the measurements of the particular subwoofer being calibrated.
Does anybody know if the upcoming Dirac BMM will address the issue I'm having? I hear it's supposed to test speaker combinations.
The Dirac Bass Management module has the option to address subwoofer/speaker blending. Whatever adjustments need to be made will happen around the crossover region. Don't know if that will require flipping the polarity of the entire subwoofer. As for optimizing the phase between pairs of speakers, you don't have to wait for the Bass Management module since Dirac 2.0 has already been doing that since it was released (a year ago?).
 
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