When using a high level connection close to the main speakers, how do you overcome the problem of the additional group delay of the subs causing a time integration error in the crossover to the subs?
Iâve only set the REL fase in 180. Iâve done a lot of measurements and try differences placement after I got the REL. Iâve never heard system with sub(or without sub) that the bass is so controlled, dry and integrated that my own. I didnât like to boast about own system, but I proud about the bass in my setup.
So as I understand it, you use speakers with a bass reflex enclosure?
Then you set the subs back behind the speakers a distance of λ/2 at the main to sub crossover frequency but with a 180° electrical phase shift for the subs; thus putting them 360° out of phase with the main driver, but in phase with the reflex port?
Presumably you see this 360° transition in the minimum phase plot and in the impulse response you get two pulses a few milliseconds apart?
Itâs very odd that REL use a fifth order bass alignment on a sub with intention to be used for HiFi as well as HT usage as this causes further temporal issues.
apparently Sevald hears no temporal issues. The theory canât predict allâŠ
Theory canât predict what someone will hear (as in how an specific personâs brain will interpret the signals it gets), but in well categorised areas (such as the physics of longitudinal waves) it can accurately predict what really will happen.
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So the phase switch on a REL is so that one can put the Subs into phase with the ones Main Speakers. Pretty simple to do one simply plays any track with deep repeating bass line and adjust phase, one position will be louder and thatâs correct in-phase. With dual subs just do one at a time.
@Sevald You said âThey are connected hi level at my speaker with the black and yellow red wire( not the yellow) work just awesomeâ
So Iâm assuming that you have TWO REL cables? On one you run Yellow + Black ( Left Speaker + Sub) and on the right channel you run a separate REL cable using just the Red + Black (Right speaker + Sub) ?
@Sevald Please see above on correct Phase Adjustment on RELâs and itâs also described in the Owners Manual 
@Sevald Iâm also wondering why you put the subs up on those Crate looking things? It does look cool (and nice looking room btw) But youâre loosing bass output and integration with the Main speakers ⊠FWIW the subs are Designed to be on the floorâŠIâd suggest putting the subs on the floor, right where they are just without the stands. Then set the phase correctly for each as I described. Also a one REL setup trick is to set the crossover lower but use more gain⊠Good Luck
Thatâs not necessarily true, it depends on the room acoustics.
That is fine for HT use, but is a very misguided approach for use integrating a sub into a 2ch HiFi system.
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Unfortunately thatâs a massive oversimplification.
It doesnât take into account the differences path length between the main speakers and the sub to the listener, nor does it take into account the group delay of the sub, since these can have phase equivalents that have values other than 0° or 180°.
If you place subs beside the speakers you need to put a delay into the feed to the main speakers to compensate for the group delay in the sub. If you donât do this you wonât get the correct temporal alignment.
One alternative is putting a delay into the feed for the sub is also possible to give a 360° delay to the sub, however although this results in continuous signals being in phase (hence giving the correct frequency domain), it results in a double pulse in the impulse response (i.e. itâs not correct in the time domain). The net result of this is that the sound from the sub is delayed by a full cycle (at crossover frequency only!).
A better alternative is to place the sub(s) closer to the listener by a distance where the speed of sound from the main speakers gives a delay equal to the subâs group delay. This way the sound from the sub is both in-phase with the speakers drivers, and not delayed.
I can understand all of your questions about my sub setup. And why is the sub lifted on stand? Well, it works. I think itâs looks stupid to have them at stands, Same at have them fase 180â. It work. If I push forward at line with main speakers I can turn the fase to 0â. But then at got a problem with my screen. Crossover it set low. 45-50hz. In theory my setup is maybe all wrong. I wish you all can com and listen. The bass is dry and totally controlled. Why should I change? Sorry for my bad English:-/
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Unfortunately @Xanthe you are wrong. Heres the link to the REL Tuning and Setup Guide. https://rel.net/how-to-tune-a-rel/
Just as I wouldnât be so egomaniacal to suggest to Lewis Hamilton how to Apex a Corner, Or to tell Alan Shaw how to tune his speakers. Maybe you should consider that you donât know everything. Nothing is so difficult as one who knows it all, but doesnât really, and still thinks they do.
Please @Sevald if youâre confused you can of course call REL and ask them.
And FYI I actually spent a couple days taking the REL Master setup course that REL offers to their dealers⊠But WTF do I knowâŠ
Hi Rick,
The instructions there are absolutely correct⊠for setting up a low frequency effects sub.
Those instructions are not right for setting up a sub for use with music.
That positioning will produce the loudest response but also an extremely uneven response.
I have done the research, and I do understand the physics; rather than just relying on one manufacturerâs opinion, Iâve looked at the recommendations of many manufacturers, particularly the ones who focus on music setups rather than home theatre.
Iâve also tried that setup, and it was no where near as good as my current setup (which fits with the principles established by acoustic modelling).
Hello XantheâI have a couple of questions. First can you describe where the group delay in the subs come from? I would like to understand more about this effect. The second question, if one is using planar speakers, how does that change your suggested alignment proceedure.
As an aside, Meridian in their dps speakers/subwoofers, does do a base alignment for this group delay.
@Xanthe youâre 100% rightâŠ
But for anyone whoâd prefer RELâs thoughts on how to setup their REL products hereâs the first paragraph from RELâs Tuning Guide ( Link in previous post) )
âREL products are not traditional subwoofers, but true Sub-Bass Systems. A REL is designed to augment the performance of FULL RANGE speaker systems in order to provide, in certain cases, linear response below 15Hz. A REL will take advantage of the physical room acoustics to provide deep pressurization as no traditional subwoofer can. For best results, the REL should be placed in one of the corners behind the speakers. Remember, we are dealing with True LOW bass pressurization with RELs. Low bass pressurization below 40Hz is best derived from corner placement, where the most linear and efficient low bass can be produced because the subwoofer is able to take advantage of the tangential (corner to corner) axis which is typically the longest distance in a roomâ
I find it interesting that you follow Naimâs protocols like Naca 5 speaker cable, length and all their other recommendations like a religion; but RELâs guidelines, you just canât get along with⊠Iâm surprised since they are a very British companyâŠ
Hi @bailyhill,
Unfortunately I have insufficient knowledge and experience of dipole panel speakers to be able to comment on their bass alignment.
The group delay is much easier to answer⊠The main sources are the low pass filter, the high mass of the driver cone, and, to some extent, the cycling of the switching frequency of the class D amplifier. (The specialist Class D amps designed for subs often use a switching frequency thatâs lower than is customary for full range audio amps.) Itâs also worth noting that it takes a few switching cycles for a Class D amp to stabilise to a step change of input. Taken together these typically result in a group delay of between 2.5 and 5 milliseconds.
I donât use NAC A5, but I do use a speaker cable thatâs electrically very similar. I follow the electrical recommendations for Naim amps as those recommendations are based on sound physical principles, long established in electronic practices.
On the other hand, instead of working from good scientific principles, the piece from REL that you quote shows itself to be marketing hype right from the first sentence! (The air doesnât know how the pressure wave was generated and REL subs are no different in this.)
Incidentally my sub setup where it is is -3db at 16Hz, so it like many subwoofers, it meets the criteria for a Sub-Bass (i.e. infrasound) system (as typically used for HT applications), as well as giving a reasonably flat frequency response (prefered for music systems), unlike the unsatisfactory result I got when I put the sub in or anywhere near the corner of the room.
Hey Rick, i see that you have a lot of shunyata cables and power conditioner. More expensive than the electronics, the SN2. Why this non common choice?