Digital Room Correction - Anyone using it?

[Macca]

Two systems at the recent Cranage Hall show, both very expensive, both sounding very poor, both using digital room correction.

Is anyone using DRC and getting a good sound? I don't mean an antimode on the sub or similar, I mean correction of the whole FR.

Anyone try it and not like it? Has anyone heard a system using DRC which was delivering a good sound?

I'm interested in any views/experiences

Thanks

[YNWaN]

I don't use it across the whole frequency range, just on the bass driver. That isn't because I believe it will ruin the sound though, more that it just isn't needed on the mid and treble.

I thinks it's way over simplistic to look at the two Cranage systems (not sure which the second was) and point a finger of accusation at any specific element, particularly as we don't know what was implemented. I do think it's important not to apply too much correction though; in my own case I don't try to correct any dips.

[jandl100]

No, just an Antimode - but it gets rid of a significant 50Hz bass peak with no detrimental effect, imo. :thumbsup:

But I lived for a long time without it and don't regard it as essential.
-- in fact some music sounds best with the bass peak back in. :rock: :eyebrows:

I don't think I've heard a full DRCed system.

[Macca]

The two systems I was referring to were TAD and the House of Linn system with the active ATC and the Sondek LP12

I'm not saying the DRC was responsible for the poor sound but I suspect it was (what else could it be?) however if someone says 'yes I use it/have used it and I get a good sound' then it would sort of rule it out as being the culprit.

[YNWaN]

Did the TAD system use full frequency room correction?

[jandl100]

I've heard TAD and ATC based systems sounding pretty awful without any sign of digital room correction. ;)

[YNWaN]

I'm not saying the DRC was responsible for the poor sound but I suspect it was (what else could it be)?

Well it could be loads of things - the source, or source material, amps, speakers - or it could be excessive use of mains regeneration smoothing paraphernalia (both the Linn and TAD rooms could be accused of this - particularly the Linn/ATC). ATC's do have a cool, somewhat detached presentation in my experience and a many of todays high-end amps have the kind of sound heard in the TAD room (I've already doubted the quality of the files used).

[Macca]

I've heard Active ATC before and thought them pretty good. TAD is totally new to me but IME if a system sounds poor in quality terms (rather than in presentational terms) it is pretty much never the speakers unless they are broken.

I'm pretty much convinced it was not the source or source material at fault. Yes they could have been using a loosy file on the TAD system but I would be very surprised and in any case it would not be sufficient account for the poor sound they were getting.

I don't see how a mains regenerator can make the sound worse. Better, yes, no improvement, yes. But not a degredation.

I thought I had read somewhere that the TAD system used DRC, perhaps it didn't.

In any case what I am interested in is anyone who has had good results with full DRC. Room correction (both active and passive) is touted by many as a universal panacea and the answer to pretty much any 'my system doesn't sound so good' query so I wanted to know if my experiences were typical or not.

[cloth-ears]

I have dabbled with DRC and after looking at the pros and cons I found it had little to offer. Correcting the response curve to suit a particular room sounds like a good idea but unfortunately speakers are “dynamic”. They are constantly changing. There are many reasons for this but suffice to say that a speaker that may sound a little naff at low volume may spring into life at higher volume levels. The opposite may and often does apply

It’s a bit like using a graphic equaliser to flatten the response curve. Every time the music level goes up or down a different amount of correction would be required. For this to happen in real time the DRC can only correct the error after it’s been made.

Look at it again in a few years perhaps but I believe its a no no

[YNWaN]

I've heard Active ATC before and thought them pretty good. TAD is totally new to me but IME if a system sounds poor in quality terms (rather than in presentational terms) it is pretty much never the speakers unless they are broken.

Well we will have to agree to differ then but I've certainly heard many systems that sound bad primarily because of the speakers - they weren't broken either.


I'm pretty much convinced it was not the source or source material at fault. Yes they could have been using a loosy file on the TAD system but I would be very surprised and in any case it would not be sufficient account for the poor sound they were getting.

Well you're not sure if the TAD system even used room correction but you are sure their was no issue with the quality of their files. First the speakers can't be the result of the poor sound and now it can't be the source - you seem to be determined to disregard every option other than your own preference, whether there is evidence or not.


I don't see how a mains regenerator can make the sound worse. Better, yes, no improvement, yes. But not a degredation.

You don't! Have you never had a demonstration of any? I have heard demos, in fact I was present at a demo of the very PS Audio ones that Brian and Trevor were using and preferred the sound without them finding that they tended to rather smooth out the sound.


I thought I had read somewhere that the TAD system used DRC, perhaps it didn't.

I've not read that it was and as far as I know it did not use DRC. If so then I don't know where that leaves us as you doubt it is the source, rule out the speakers and it can't be the mains. Presumably it has to be the amps...


In any case what I am interested in is anyone who has had good results with full DRC. Room correction (both active and passive) is touted by many as a universal panacea and the answer to pretty much any 'my system doesn't sound so good' query so I wanted to know if my experiences were typical or not.

The only person I know who regularly trots out 'the room is the issue' stance is Keith from Purite Audio but then he sells DSP and passive room correction products so it's very much in his interest to push this idea. I'm not aware of anyone else who claims room correction is any kind of 'panacea'. I've got some passive room treatments that I built some time ago and they are beneficial. I've also heard a system that operated full DSP across the whole frequency range. It's effect was quite subtle but I overall we preferred the sound with it out of circuit (but this was in a room that didn't need much correction - in a more problematic room the effect may have been more dramatic).

You haven't actually said what 'your experiences' with DRC are so its not possible to confirm if they are typical or not. However, it certainly looks like what you really are looking for confirmation that it's a 'load of rubbish'.

[Macca]

Mark you make some fair points but I'm not looking for confirmation that it is rubbish although it may seem that way. In theiry it has a lot to offer and as someone who prefers digital recording and replay over analogue I certainly don't have any axes to grind here.

Indeed I was looking for exactly the experiences you have related in order to try and make a bit of sense of what I heard. I really don't have much experience of high end systems, mains regen or drc so I am asking questions albeit in a devil's advocate sort of way.

[purite audio]

Well we will have to agree to differ then but I've certainly heard many systems that sound bad primarily because of the speakers - they weren't broken either.



Well you're not sure if the TAD system even used room correction but you are sure their was no issue with the quality of their files. First the speakers can't be the result of the poor sound and now it can't be the source - you seem to be determined to disregard every option other than your own preference, whether there is evidence or not.



You don't! Have you never had a demonstration of any? I have heard demos, in fact I was present at a demo of the very PS Audio ones that Brian and Trevor were using and preferred the sound without them finding that they tended to rather smooth out the sound.



I've not read that it was and as far as I know it did not use DRC. If so then I don't know where that leaves us as you doubt it is the source, rule out the speakers and it can't be the mains. Presumably it has to be the amps...



The only person I know who regularly trots out 'the room is the issue' stance is Keith from Purite Audio but then he sells DSP and passive room correction products so it's very much in his interest to push this idea. I'm not aware of anyone else who claims room correction is any kind of 'panacea'. I've got some passive room treatments that I built some time ago and they are beneficial. I've also heard a system that operated full DSP across the whole frequency range. It's effect was quite subtle but I overall we preferred the sound with it out of circuit (but this was in a room that didn't need much correction - in a more problematic room the effect may have been more dramatic).

You haven't actually said what 'your experiences' with DRC are so its not possible to confirm if they are typical or not. However, it certainly looks like what you really are looking for confirmation that it's a 'load of rubbish'.

The important point for me, is not whether you use DRC or parametric EQ or passive acoustic treatment but that everyone seriously interested in audio reproduction ,should be aware of the huge contribution to the overall sound quality that your room/speaker interaction makes.
I would recommend that everyone acoustically measure their room, REW software is free to download, the results are always fascinating, and once you are aware of specific issues ,you can treat them and enjoy a real and possibly huge improvement n sound quality.
Keith.

[Hipper]

I’ve been using a digital equaliser full frequency range for some ten years. It’s not quite DSP as I understand it but it attempts to be.

My advice is:

First do your best to position your speakers and listening chair to get the best sound. In particular you are listening for bass (up to 300Hz say). You can use music and ears, test tones and SPL meter (or ears), or most accurately, some software such as Room EQ Wizard (REW), which is free. However for REW you will need to buy other equipment, such as microphone, stand, and other bits and pieces to connect to a laptop. It also takes a lot to learn but there is much advice around. I would say though that the resulting frequency response is not the end, but the beginning. Ultimately you must adapt to your ears.

Secondly consider room treatment. It really does make a substantial difference, mostly allowing you to hear the bass of the music and not the room.

Finally, positioning and room treatment get you nearly there, so I use an equaliser (a Behringer DEQ2496) to complete the job. This also allows me to adjust for my hearing - we all hear differently. I’m sure it’s not perfect, but I like the result!

You will often hear people say that using an equaliser of any sort messes things up somewhere. All I can say is if I take my equaliser out of the system it doesn’t sound as good. Recently I was discussing this with someone who is fairly knowledgeable on music replay and he said that EQ damages transients. I now know how to listen for transients and could detect no obvious damage when putting the EQ in or out.

A lot of people will decry all of the above. If they’ve tried it, fair enough. Mostly though it is usually argued against on principle. Ignore those! The best thing to do is try it for yourself. The reason it isn’t more popular is because it’s difficult and time consuming to understand and do

Keith sells a miniDSP with Dirac, which is DSP, and seems to be relatively simple to use. I’ve not tried it but perhaps there might be possibilities of a trial? I understand it’s particularly useful for people who are limited in what they can do in their listening room regarding room treatment and positioning. I don’t think it can replace positioning/room treatment but it will go some way to achieving what that does.

.

[Reffc]

There's loads of opinions, for, against and ambivalent towards digital room correction by those who have tried it, as well as those who have not.

As Keith mentions, the room is part of the issue, but by no means the whole issue. DSP is seen by some (rather unfairly I think) as a solution looking for a problem and that the easiest way of selling it is to always point to room correction as being necessary which isn't always the case, depending on personal tastes. You can present as much objective evidence as needed to try and convince someone they need something but ultimately everyone has different tastes and personal choice will come into it for most people, who may be suspicious of selling a solution to a problem that they may not be convinced or concerned about. The answer is perhaps for those people who are concerned but remain unconvinced to do a little more background work to discover if it is for them or if there are cheaper or easier solutions, or indeed of they need anything at all.

To flesh things out a little, there are three main considerations:

1. The recording;
2. The room;
3. the loudspeakers (and their positioning).

Change any one of those and SQ will change. The recording isn't something we can do much about, so that leaves the room and the speakers.

DSP correction works on the principle of measurement taken at ONE position only (the normal listening spot) and ideally looks for a total far field power response to be as even as possible at the chosen listening volume but it can only attempt this by modifying the direct response.

For an accurate picture of power response, the mic used is very important indeed. It needs to be omnidirectional . It also needs to be certified or calibrated so that you know what you measure will be accurate. The proximity effect comes into play especially for cardioid mics distance from the sound source which can see a boosting of measured bass response which may not actually exist!

Volume comes into the equation only because most loudspeakers will have been designed with a response curve specific to a design point SPL. Human hearing sensitivities mean that we do not hear "flat" except at specific (usually higher) volumes where there is a lessening of the F-M effect. This needs some consideration when considering total far field power response. It is rare for a manufacturer to actually state at what SPL their response curves were tested at. I only know of a few who quote "curve measured at XX dB SPL" This is more important for some speaker designs than others, as some really only start to behave, dynamically speaking, as intended at rather high SPLs, so loudspeaker choice for your personal listening tastes and rooms is another consideration.

Speaker choice is often a big factor and there's little if any point in investing in room correction of any sort if you buy a used pair of speakers for a few hundred quid which have a large peak at say 50 to 60Hz. It would be cheaper to sell those on and buy a better designed pair and you could do this for much less than the cost of room treatment of any sort at all, be that passive or digital correction.

DSP cannot accurately modify total power response without (some times significantly) messing up direct response, so tends to be used for LF correction where there are unwanted peaks in response. Bass is omni-directional, so changes to direct response are less important for LF.

However, the frequencies where DSP can start to mess things up kick in at different levels depending on the speaker design, driver piston diameter and dispersion characteristics, but one rule of thumb (albeit a rough one) is to keep it constrained below baffle step frequencies and it can be beneficial. Above those frequencies and it can start to get a lot more complicated depending on the room and speakers.

Passive room correction is normally favoured as the more accurate way of dealing with total power response (the sum of directional and reverberant/reflected sound), but again, this can change with volume and recorded material, so really, no form of room correction is ever going to be a total guarantee of audio nirvana, only a means to improve rooms where acoustic issues dominate listening pleasure.

Before rushing out to treat a room or invest in all the digital gubbins and mics you may first want to consider the speakers themselves.

Bass boom can often be tamed by different speaker positioning which requires no financial outlay. Avoid setting up standing waves in room corners especially. I have one client who suffered with room boom issues and he invested over £600 in digital room correction. The simple fix, sadly discovered too late was simply to move the speakers so that they were further away from side walls and not equi-distant from side/rear walls as they had previously been. This immediately resulted in a dramatic improvement at the listening position, DSP disconnected.

For some rooms the dimensions/geometry will dominate LF response with no improvement possible by shifting speakers around. My advice is to either use a better suited listening room if you are able to, or if not, you may have to consider passive or digital correction of some sort. Passive tends to be more intrusive but can be effectively done for some rooms on a tight budget if going the DIY route where you have the space. For convenience, as most people don't have the luxury of dedicated rooms, digital correction of the LF is more convenient but prices as yet remain relatively high.

[YNWaN]

A very well considered response that I really couldn't agree more wholeheartedly with. In my first hand experience I would add that DSP is not an easy panacea to all room/speaker interaction issues. It doesn't mean that you are free to put your speakers, designed for free space positioning, in the corners of your room and expect magic frequency response manipulation to occur without compromise. In addition, in my experience, the higher the frequency the more obvious the manipulation is and the more sensitive the ear is to such modification. Most retailers of such systems do try to sell them as 'magic bullets' but they intentionally choose to simplify e whole subject so as to make it seem more approachable. The truth is that, as with any sophisticated problem, it takes a bit of study.