rel acoustics live subwoofer demo

[goat76]

I find it difficult to understand how certain parts of a signal can be delayed more than others, as claimed. The entire signal sent to the subwoofer passes through the processor, which operates with a fixed clock speed and follows a predetermined DSP program with a specific number of instructions it needs to run before sending the processed signal downstream to the amplifier module. As a result, it cannot differentiate between different parts of the signal in terms of processing time.

They are against the type of DSP processors that are built into some subwoofers. In such instances, there is a risk that the signal get delayed to the subwoofers in comparison to the unprocessed signal that reaches the main speakers.

 

[goat76]

It's great that you have low distortion mains, but in general very few have main speakers that have lower distortion below 100hz than two good subs. Also, the reason to high pass the mains isn't only to reduce distortion. Speakers are also very often placed in a way where you will get peaks and/or dips below 100hz. So if you employ a subwoofer to fix this but don't highpass the mains, you won't be able to, since the speakers still excite the peak/dips.

In my opinion, going with main speakers that try to go lower in bass than what the physical size of the speakers allows without generating a high level of distortion, is simply a bad choice of loudspeakers.
Almost all loudspeakers on the market need additional subwoofers for a full-range sound without having high level of distortion, so there is very little point in looking for too small speakers with low bass extension.

If someone has the problem of not being able to positioning the main speakers optimally in the room, what makes you think they have the space to position the subwoofers optimally?

Second, the story "Rel is easy to integrate" is likely true since they insist on crossing them over super low below the speakers. When the subs are only playing a single octave (20-40hz), it's limited how many room modes they can excite, and it will naturally be much easier to make them behave. This isn't a consequence of any special quality in Rel subwoofers, it's a consequence of crossing them over very low. The same would happen with any other competent sub.

You are correct, REL subwoofers aren't any better in that regard and most other subwoofers could be used in the same way acting just as “extensions” for the lowest bass region. I have never said other subwoofers can't be used the same way, it's just that most other manufacturers go for other solutions as their main goal.

 

[Old_School_Brad]

They are against the type of DSP processors that are built into some subwoofers. In such instances, there is a risk that the signal get delayed to the subwoofers in comparison to the unprocessed signal that reaches the main speakers.

It's not just a risk IMO. It will be delayed with the processing time of the DSP. This is true for most active subwoofers, so you adjust the timing of the main speakers accordingly.

 

[Hear Here]

For me the big problem is the recommendation of high level inputs. It's just so dumb that it makes me question everything about them. The fact that their subs are adorned with crown logos all over them is also pretty gaudy.

I agree with you about recommending high-level connection. However, Avantgarde Acoustics who build hybrid speakers that feature a self-powered bass enclosutre (effectively a subwoofer), also recommends high level for 2-channel music, but low-level in AV systems. Why, I cannot say, but it's certainly easier to use high-level as only a speaker cable is needed between the amp and speaker.

My gripe about REL is that they don't offer an XLR connection for their S812 sub (quite a costly item) and the gain offered by the RCA connection is far too low if you have high sensitivity main speakers. My AGs are quoted as 107 dB and the subs at full volume are unable to offer anything of value to the music.

 

[sigbergaudio]

If someone has the problem of not being able to positioning the main speakers optimally in the room, what makes you think they have the space to position the subwoofers optimally?

Let's say a corner ends up being a good position. You may technically have space to put one of the speakers in that corner, but for obvious reasons (reflections from side wall, asymmetric stereo placement) that won't be a great idea. While a subwoofer is another matter.

So to put it differently: The fact that you want your main speakers symmetrically placed and typically right in front of you, means you are very limited with regards to where you put them. While subwoofers do not have the same constraints. They can be placed in corners. They can be placed asymmetrically. So it's not just about available space.

 

[Spkrdctr]

It's close to possible to make anything out of a microphone recording on YouTube other than conclude that “there will be more bass” if you add a subwoofer to the speaker system. I would definitely not judge the sound of being better or worse in such a demo.

I agree. listening to anything to determine quality, frequency attributes and such off a YouTube video is just plain nuts. Trying to show the sound quality of giant Legacy speakers for example (they are huge and have massive impact) to someone which is listening to the video on their tiny computer speaker set up is downright silly. But it happens everyday all day long. People do some really weird stuff!
Legacy speaker (one of many)

 

[Titurel]

I didn't watch or listen to the webcast, but my previous subs were from Rel. I don't subscribe to all of John Hunter's ideas, BUT, when used with speakers that rolls off benignly, like the Mag. 3.7i, the high-level inputs proved easier to integrate and having separate line-level inputs for LFE was also useful. Using semi-automated DSP, like Dirac, was not quite straight forward (REW is an highly recommended adjunct), but the results were likewise better using the high-level inputs.

For speakers with less well behaved (or more vulnerable) bass radiators, I would recommend using the line level inputs with more conventional bass management . As with most audio gear, price, size, performance, and WAF must be balanced.

Why did I switch brands? 1) more bottom end for the buck, 2) built in sub EQ, 3) my new mains benefit from the added protection off an active x-over.

 

[PHD]

I find it difficult to understand how certain parts of a signal can be delayed more than others, as claimed. The entire signal sent to the subwoofer passes through the processor, which operates with a fixed clock speed and follows a predetermined DSP program with a specific number of instructions it needs to run before sending the processed signal downstream to the amplifier module. As a result, it cannot differentiate between different parts of the signal in terms of processing time.

It actually can, but due to an all-pass filter used for phase control. In order to remove room modes/dips, the DSP, among other things, alters the signal's phase for some specific frequencies. There is a distinctive difference between phase shift and time delay. A signal could have a time delay of 3 years but have a 30-degree leading phase compared to another signal. If you apply phase shift, you also add some latency to parts of the signal corresponding to the altered frequencies. This may impact steady state and transient response differently. You alter the phase for steady-state response and may end up delaying some transient components. Not sure if this is true, but this is exactly what REL engineers are claiming.

 

[goat76]

Let's say a corner ends up being a good position. You may technically have space to put one of the speakers in that corner, but for obvious reasons (reflections from side wall, asymmetric stereo placement) that won't be a great idea. While a subwoofer is another matter.

So to put it differently: The fact that you want your main speakers symmetrically placed and typically right in front of you, means you are very limited with regards to where you put them. While subwoofers do not have the same constraints. They can be placed in corners. They can be placed asymmetrically. So it's not just about available space.

There can be many different reasons why a solution works better in one situation over another, and I mostly just wanted to point out that the philosophy REL uses of setting up and connecting the subwoofers isn't necessarily the wrong way of doing it. I find it very easy to get them to integrate seamlessly with the main speakers, and that should be respected as there are so many people who struggle a lot to get their subwoofers to integrate, and many of them even give up and decide they don't like subwoofers in their systems.

How many times have you read the sentence "I prefer the sound of my main speakers without subwoofers"?

The thing is...
I don't think there are that many people who would prefer a limited-range sound system over well-integrated subwoofers that give a full-range sound, but some people may have never experienced it or just haven't gotten the subwoofers to integrate well with the main speakers, and I believe the solution to their problem can be the "REL way" with their ease-of-use high-level connection.

 

[sigbergaudio]

There can be many different reasons why a solution works better in one situation over another, and I mostly just wanted to point out that the philosophy REL uses of setting up and connecting the subwoofers isn't necessarily the wrong way of doing it. I find it very easy to get them to integrate seamlessly with the main speakers, and that should be respected as there are so many people who struggle a lot to get their subwoofers to integrate, and many of them even give up and decide they don't like subwoofers in their systems.

How many times have you read the sentence "I prefer the sound of my main speakers without subwoofers"?

The thing is...
I don't think there are that many people who would prefer a limited-range sound system over well-integrated subwoofers that give a full-range sound, but some people may have never experienced it or just haven't gotten the subwoofers to integrate well with the main speakers, and I believe the solution to their problem can be the "REL way" with their ease-of-use high-level connection.

You are preaching to the choir with regards to well-integrated subwoofers sounding better than stand alone speakers. I do not think the REL way is the ideal solution, but as long as you don't high pass the mains, there are not so many other options to choose from. So for such a system, you do a low crossover point. You'd still be better off using RCA/XLR if available, but that's a minor point.

A better solution (imo) would be high passing the mains and allowing the subwoofer to play over a broader frequency range. But I would say that of course, since that's how we design our systems.

 

[goat76]

You are preaching to the choir with regards to well-integrated subwoofers sounding better than stand alone speakers. I do not think the REL way is the ideal solution, but as long as you don't high pass the mains, there are not so many other options to choose from. So for such a system, you do a low crossover point. You'd still be better off using RCA/XLR if available, but that's a minor point.

A better solution (imo) would be high passing the mains and allowing the subwoofer to play over a broader frequency range. But I would say that of course, since that's how we design our systems.

I hope I'm preaching to the choir, at least for the larger part of the choir, but then we still have those who prefer their main speakers without subwoofers as they struggle to get them to integrate well. I have read that many times, even here on ASR.

 

[Hear Here]

A better solution (imo) would be high passing the mains and allowing the subwoofer to play over a broader frequency range.

All well and good if the main speakers are not capable of delivering the full frequency range. Mine are, so subs are only needed (maybe or maybe not) if the room acoustics adversely affect the main speakers' ability to deliver cleanly

I hope I'm preaching to the choir, at least for the larger part of the choir, but then we still have those who prefer their main speakers without subwoofers as they struggle to get them to integrate well. I have read that many times, even here on ASR.

Yes, subs should be unnecessary (and probably undesirable) if the main speakers are of the right TYPE for the room, are capable of delivering the full frequency range, are expertly positioned and set up and the room's features (carpets, curtains, etc) are sympathetic to the delivery of music.

 

[sigbergaudio]

All well and good if the main speakers are not capable of delivering the full frequency range. Mine are, so subs are only needed (maybe or maybe not) if the room acoustics adversely affect the main speakers' ability to deliver cleanly

That is great for you, but not generally applicable. The vast majority of people do not have speakers that can play down to 20hz in-room without compression at loud levels. And even fewer have both that, and are so lucky that they get an even frequency response in the bass from just two speakers.

I won't say it's one in a million situation, but it's certainly one in a hundred.

 

[Sir Sanders Zingmore]

For me the big problem is the recommendation of high level inputs. It's just so dumb that it makes me question everything about them.

Ok I’m going to display my ignorance here. The “high level input” thing is a very common criticism levelled at REL, but what is actually wrong with doing it that way?

 

[NTK]

Ok I’m going to display my ignorance here. The “high level input” thing is a very common criticism levelled at REL, but what is actually wrong with doing it that way?

By definition, using high level inputs means that you'll have to send full range signal to the main speakers. In "bass managed" systems, the mains are high pass filtered and are relieved of their low frequency duties, so they can "concentrate" on reproducing mid-bass and above, and the usual results is cleaner mid-bass (and higher max SPL). You cannot have bass managed system with high level inputs.

Also, speakers are frequency and level dependent reactive loads, and generate back EMF. If the amp output impedance is high (resulting in a system with low damping factor), the signals to the sub(s) using high level inputs can be somewhat corrupted.

[Edit] The signal quality of the high level inputs are also dependent on the output signal quality of the speaker amp. If the amp clips, the sub(s) will be receiving clipped inputs.

 

[Sir Sanders Zingmore]

By definition, using high level inputs means that you'll have to send full range signal to the main speakers. In "bass managed" systems, the mains are high pass filtered and are relieved of their low frequency duties, so they can "concentrate" on reproducing mid-bass and above, and the usual results is cleaner mid-bass (and higher max SPL). You cannot have bass managed system with high level inputs

Isn’t this is the case with any system that doesn’t high-pass the mains? If you can’t high-pass the mains, sending a line level signal to the sub isn’t going to help “relieve” the mains.

Also, speakers are frequency and level dependent reactive loads, and generate back EMF. If the amp output impedance is high (resulting in a system with low damping factor), the signals to the sub(s) using high level inputs can be somewhat corrupted.

[Edit] The signal quality of the high level inputs are also dependent on the output signal quality of the speaker amp. If the amp clips, the sub(s) will be receiving clipped inputs.

I understand this, but isn’t it also precisely REL’s marketing too? That is, high level connections ensure the “sound” of your amp is passed on to the subs. If your amp does have a “sound” it’s almost certainly because of non-linear behaviour cause by clipping or possibly issues handling back emf. Assuming you like the “sound” of your amp (that is you like the way it distorts) it makes sense that you’d want the same sound from your sub.

 

[NTK]

Isn’t this is the case with any system that doesn’t high-pass the mains? If you can’t high-pass the mains, sending a line level signal to the sub isn’t going to help “relieve” the mains.

Yes. However, the Rel method makes sure you will not be able to bass manage your system.

I understand this, but isn’t it also precisely REL’s marketing too? That is, high level connections ensure the “sound” of your amp is passed on to the subs. If your amp does have a “sound” it’s almost certainly because of non-linear behaviour cause by clipping or possibly issues handling back emf. Assuming you like the “sound” of your amp (that is you like the way it distorts) it makes sense that you’d want the same sound from your sub.

Rel made a claim (or BS) that it is "better". So we just assume their claim is legit? What about showing some scientific studies that verify their claim?

 

[Sir Sanders Zingmore]

Yes. However, the Rel method makes sure you will not be able to bass manage your system.

Agree, but the issue there isn't about line level vs speaker level, it's about bass management. Clearly, proper bass management is preferable but it's not always possible.
For people who for various reasons don't want to (or can't) bass manage their system I'm trying to understand why speaker-level connection to subs is worse than line-level?

Rel made a claim (or BS) that it is "better". So we just assume their claim is legit? What about showing some scientific studies that verify their claim?

Without evidence (which of course they won't provide), we shouldn't assume anything about their claims.

 

[NTK]

Agree, but the issue there isn't about line level vs speaker level, it's about bass management. Clearly, proper bass management is preferable but it's not always possible.
For people who for various reasons don't want to (or can't) bass manage their system I'm trying to understand why speaker-level connection to subs is worse than line-level?

If for whatever reasons one has to forgo the benefit of bass management (which is available from practically all home theatre processors/receivers and some 2-channel amplifiers such as Wiim Amp and others), it will likely make little difference. However, I can't think of a good scientific reason that high level connections will give better sound quality than line level connections.

 

[Old_School_Brad]

It actually can, but due to an all-pass filter used for phase control. In order to remove room modes/dips, the DSP, among other things, alters the signal's phase for some specific frequencies. There is a distinctive difference between phase shift and time delay. A signal could have a time delay of 3 years but have a 30-degree leading phase compared to another signal. If you apply phase shift, you also add some latency to parts of the signal corresponding to the altered frequencies. This may impact steady state and transient response differently. You alter the phase for steady-state response and may end up delaying some transient components. Not sure if this is true, but this is exactly what REL engineers are claiming.

Yes, that’s true, but this is about phase displacement. My response was focused solely on time delay.

The audibility of phase changes roughly aligns with the equal loudness contour, meaning we’re most sensitive to phase shifts in the midrange frequencies and far less sensitive below 200 Hz. This distinction is important when considering REL's claims in this context.