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I think you mentioned A-weighting before. This weighting scale was developed for assessing speech intelligibility in communications systems. It is not more accurate aurally in general.
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Monoprice HTP-1 Home Theater Processor Review
- Thread starter amirm
- Start date
I was given this information for the RMC-1:
Unbalanced out of 2.25 VRMS 4.5V peek
Balanced 4.5V RMS, 9V peak
- Rich
Here is a link to Amir's tests of an Emotiva AVP. Note the headless panther. That's one headless panther for Emotiva and one headless panther for Monoprice. This score keeping is for those who can't make an evaluation based on the measurements, and must rely of the status of the panther. Clearly relying on the status of the panther has the advantage in that each review in Audio Science can be "read" in less than a minute.
https://www.audiosciencereview.com/...urements-of-emotiva-xmc-1-gen-2-pre-pro.9225/
Based on the picture of an RMC-1 circuit board online, Emotiva uses:
One AK4490 per channel - mono, differential mode. Based on Emotiva's description of the product, my guess is that the (+) and (-) outputs are paralleled for input to two differential amplifiers. The inputs to the two amplifiers would be reversed to produce a (+) and (-) differential output. This arrangement allows the signal to be handled in the full differential mode from the DAC IC to the XLR outputs. The opamps used are 5532 dual units. This is an industry standard opamp. The datasheets on this opamp often aren't really complete. Douglas Self's book, "Small Signal Audio Design" 1st or 2nd Edition, has measurements of 5532's if you are interested.
The (+) and (-) and minus legs each go through a channel of the CS3318 volume control. This means that one 8-channel CS3318 handles four differential channels. In the HTP-1 each DAC IC produces two channels and each CS3318 handles eight channels. That is the signal is converted from differential at the output of each DAC channel, to single-ended. The HTP-1 has a less expensive design. The gain structure in all this isn't clear, but from a high level the Emotiva unit can handle a signal at twice the voltage level (+6dB) as the HTP-1. The Emotiva design requires twice the DAC IC's and associate circuitry, and twice the number of CS3318 volume controls.
From the CS3318 volume control in the Emotiva unit the signal goes to output buffer opamps. Fundamentally the gain of the output is likely 0dB since each differential leg goes to a separate opamp. It would be easy to provide a high input impedance in these buffers, so that they could easily be driven by the volume control, although the exact design isn't clear. The same Neutrik male output sockets as the HTP-1 appear to be used in the Emotiva unit.
Without any gain changes, the output of the legs of the DAC plus filter output would be 2V and -2V or 4V differential. With 0dB gain in the volume control and 0dB in the output buffer the fundamental output would be +4V differential. There isn't enough detail shown online to determine if the gains noted above are the actual gains.
The Emotiva unit uses relays for output muting, which are preferred, but more expensive. The HTP-1 appears to use a MOSFET transistor for muting. It isn't clear if the MOSFET serves the same purpose as a bi-polar transistor in a typical muting circuit, or if the signal goes through the MOSFET and the MOSFET is acting as a direct solid state relay or how it works. The advantage of the MOSFET would seem to be that the design is more compact and cheaper to implement.
The description of the Emotiva unit above as noted, is based on a picture online. It would be good if others would take a look to see if the description above is on track. Determining designs from physical hardware is obviously not as good as having schematics and bills-of-material.
When Emotiva stated 4.5v peak (unbalanced) and 9v peak (balanced), did they mean max?
Peak to me indicates the peak voltage of a sine wave.
I assumed sine wave peak but will see if I can get a better answer.
4 Volt is what I am looking for since I don't think that any AVP will supply the 9.8 Vrms required for the best S/N from the AHB2.
From what I am reading, all gain modes from the AHB2 may be better than the majority of AVPs putting out higher voltage.
- Rich
OP
- Thread Starter
- #246
Oh? You seem to interchangeably wear the hat of the manufacturer and consumer. Let's see your opinion of this interview given to Audioholics on this processor which I researched before doing my review: https://www.audioholics.com/av-preamp-processor-reviews/monolith-htp-1
This is clearly wrong, correct?
You haven't said anything in this thread that indicates you are an advocate for the consumer. You are being a PR person for the company which is fine but wear that with honor. Don't say you are thinking of the consumer when you are not.
OP
- Thread Starter
- #248
The best laid plans...
- Rich
The Q/A shows the importance of this to consumers and the fact that Hobie understood this. Why it was then not watched during the final phases of the development, remains a mystery.
The standard practice is to create specs that whoever was developing this product for them would have to meet. And then verify and publish them on the website. As it is, this is ALL we have for audio spec:
This should have been a warning to folks that audio performance was not a priority.
The priority for these devices remains channel count and maximum number of logos.
Caution: You have entered the world of AV/Home Theater specifications.
An example: You'll often see specifications such a 120W RMS. Watts RMS is of course a meaningless term, and it unlikely that the 120W is actually calculated in in RMS terms, although it certainly can be calculated.
So how about peak? First note, peak is often not used in the physics/E.E. sense. Often peak means maximum V RMS.
In the real world marketing/sales people have contributed some of the specifications, which actually may be high or low. A call to tech support often gets the marketing numbers. Several calls to tech support often get different numbers. In addition the rating may be for some level of clean output, (not specified) when the maximum, say 1% or the like distortion is higher. Of course the rating could be 10% distortion and a reasonable person would use a lower number.
Let's make our own guess. For the Emotiva unit as described in a post above:
2V is the nominal output of the AK4490 DAC IC. That's 2V per leg. Assume 0dB gain for the output filter, 6dB gain for using the channels in differential format. This means the differential signal is at 4V RMS.
The above means 2V RMS per leg is the input to the CS3318 volume control That volume control is rated at low distortion to over 5V output with 2V input with 9V DC supply rails. That makes a maximum of 10V RMS for the differential signal. Of course the input to the volume control can be less than 2V and still get 5V output based on the gain available from the volume control. We don't know the actual gain structure that Emotiva has implemented in the unit.
Self, at noted in the post above, has tested the 5532 opamp. He uses 10V RMS into 500 ohms, likely with very high rail voltages. Clearly the 5532 can handle robust signal levels. Using the datasheet for the 5532 an estimate is that it can do 7V RMS with (+/-)12V DC power rails, which is about as high rail voltages as you'll typically see in consumer level AVR/AVP's. This implies 14V for the differential signal. Sadly many AVR's/AVP's use 7V DC rail voltages, which restrict headroom and also distortion performance.
Based on the assumptions of the gain structure above and the components involved, it appears the volume control would be the limiting factor and it can do a bit over 10V RMS differential. Based the 10V RMS calculation, 9V RMS seems reasonable. The distortion at that level is of course unknown. That said, it would really take an upfront agreement on what level of distortion should be used, then measurements of an actual unit to be sure of the actual value, as where to find a truly authoritative source is not obvious.
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Why not record the device's function and behaviour as it is, in the sample that was given? It's like an audit: you pull a few records from the whole and dig in, seeing if any one shows signs of anything amiss.
It seems like AVR/P manufacturers have made their way according to the standards they've set among each other ("competition"). Independent testing should, well, redefine those standards and allow input from their customers.
My Marantz AV 7701 reaches this easily. Clipping point is at 12 Vrms. Tested with 1 kHz 0dBFS via SPDIF and volume=91.
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Completely agree. Why should AVR/P be evaluated to a lower standard than audio equipment (without the V)?
If someone told me there is something about video signaling processing that interferes with making state of the art audio, that would be one thing. But I still have not heard anything other than using different (lesser) standards for AVR/P equipment.
That's a fact.
And indeed, it's the main purpose of these machines. This is what people need, at the lowest possible price. Do you think you can do better? You are welcome to give it a try.
Channel count and the Dirac (or any other competent room eq software) logo are maximally important to audio performance. As is multiple subwoofer integration.
OP
- Thread Starter
- #255
I know I can do better. I used to manage hardware, software and mechanical engineering for broadcast video companies where our customers were the pickiest in the world from top post houses to major TV networks worldwide. What I measure and scrutinize here is a walk in the park compared to meeting their needs. I would hire the top experts in their fields to design the specialty parts of the system. To wit, anytime I let a video engineer design an analog circuit it was a disaster. They would just cut and paste the app note schematics (sample design) and hope it would work. Reality was very different and we would routinely have to throw that out and get a top analog designer to come and do it right at great expense and delay.And indeed, it's the main purpose of these machines. This is what people need, at the lowest possible price. Do you think you can do better? You are welcome to give it a try.
Now, do I want to be in audio manufacturing business? Not a million years. And I certainly don't want to operate at the top of the pyramid where the volumes are way too low to get proper support from IC companies. And be able to feed an R&D team. Farming it out to a platform maker sounds attractive until you find out that they give you the first version and then wave goodbye, leaving you to holding the empty plate. I wish anyone needing support on HTP-1 a few years from now good luck.
Heck, if I can avoid it, I don't want to be in any hardware business! You have so many dependencies that can go wrong leading to long delays. It is horrible business and few know how to do it right.
I can't fathom why Monoprice is going after the high-end market. It is not something that is associated with their brand or business model. They were a reliable ecommerce company to deal with Chinese products which didn't have that component. Selling machines like HTP-1 hugely deviates from their core business.
All this said, this is their business and it is not anything to do with me one way or the other. My job is to objectively evaluate audio products and be an advocate of consumers. It is not my job to grade on a curve just because something is hard for a company to do. That is not hard for a one-man shop producing a $150 DAC.
That's a fact.
And indeed, it's the main purpose of these machines. This is what people need, at the lowest possible price. Do you think you can do better? You are welcome to give it a try.
Maybe so but this unit isn't providing that at the lowest possible price, either. And when settings(Amplifier Sensitivity) are promised in the manual and settings, but they don't actually work, is that supposed to be acceptable when you're paying $4000 for a product?
It's better than Emotiva releasing a product with promised Dirac and then never adding it, but, it's still unacceptable at these price points in my view. A Denon or Marantz AVR is a better deal in every way.
OP
- Thread Starter
- #257
Which anyone can license and do. It clearly is not enough so they want you think that they provide highest performance. Then I measure and turns out they did not pay attention to basics.
I haven’t seen anyone yet doing it better. Doesn’t look so easy judging by results.
250$ per channel is not that expensive. Including decoding for movie formats, subwoofer management and Dirac.
Is there any cheaper product, multichannel or not, cheaper than 250$ Per channel that offers all that to the customer?
Don’t get me wrong, I don’t own the Monoprice, and I am not interested in buying one. Never owned one of their products, I am not a fan.
OP
- Thread Starter
- #259
It is not a matter of easy or hard. It is a matter of something the marketing department wants done. Until now, there was no visibility into issues here. With my testing hopefully that recognition sets in and better performance is designed in. The incremental BOM cost for the kind of things I am finding is negligible.
I went over the competition in this post. If you must have 16 channels + Dirac in one box, then the Monoprice is the cheapest way to get that. But as I said in that other post, 16 channels in HT has questionable value due to the state of Atmos content, and if you're looking for the lowest price per channel with good room EQ and all the decoding you need, the Denons are a better value.
If you're trying for a genuinely high end setup, you should wait for a JBL SDP-55/SDR-35 review. I'm saying this from the perspective of someone who actually wants to buy one of these things because I eventually want a 7.2.4 Atmos setup with Auro3D upmixing capability. But I'm in no particular rush to buy a product at the $4-6K price point, if I'm buying one, it better check all the boxes.
