Room Treatment, old vs. new?

Hi folks. As I have admitted before, I am a dinosaur! That is, I learned a lot when young (when dinosaurs roamed ), and then, well, kind of was "offline" for quite a while. There are quite a few things I am trying to catch up on.

One of these is the matter of room acoustics. 60 or so years ago, a mentor of mine (a pipe organ builder) told me that the best room for an organ would be all hard walls, like brick, stone or tile, and hard floors without carpeting. He also insisted that the wall BEHIND THE PIPES should be at least 2 feet thick of solid concrete or brick! This non-resonant surface would then reflect ALL the pipe sound into the building where the reflective surfaces would provide good reverberation.

Skip to today, and you highly educated folks are speaking of "room treatments" and "bass traps" and "nodes", it's no wonder I feel like a cave man listening to I.T. guys!

I guess I am trying to ask if there is a simple to understand, inexpensive way to improve sound in a home?

~Scott (Ug)

I

Your mentor was describing the acoustics of a cathedral, but the same doesn't work in the home where we don't have huge rooms to create those many seconds of reverberation. In a residential space we would get an echo chamber with muddled sound. Even in large churches these days there is the tradeoff between what the organist and choir prefer and the less reverberant acoustics required for intelligible speech.

In smaller rooms the choice is between a very dry acoustic with carpets and overstuffed furniture and a moderately reverberant space with hardwood or tile floors. I find that choice more a matter of preference with a bit of reverberation, all early reflections of course, perhaps being better for organ music.

There is frequently a problem getting a smooth bass response in rectangular rooms, especially reverberant rooms with dimensions that are multiples of each other. Don't expect the best results from a room that is 16' by 12' with an 8' ceiling. In this difficult room try to go with carpet and corner bass traps and add any lost sense of reverberant space with surround sound.

If there is a choice of rooms for the organ then look for the space with a vaulted ceiling, non-repetitive dimensions, and openings to adjacent rooms. The more irregular the dimensions the better off you are likely to be. My opinions only, I find this an interesting topic that affects all of us.

I realize that he was speaking of a church type of space, since that was (usually) where pipe organs were built. I find myself still thinking that the wall behind my speakers should be hard and non-resonant, like brick or stone! I just don't know if that particular detail matters, do you?

~Scott

In the past I've owned speakers which were omnidirectional or even back-firing like the Bose 901's. Those certainly wanted a harder more reflective surface though I never had anything harder than ordinary gypsum wallboard.

I doubt if it makes much difference for studio monitors and similar speakers except to the extent that the surface of any wall can make the overall room more dry or reverberant. If you have hard floors try laying down a rug or two and see how the sound is affected. With a hard back wall you might try turning your speakers towards the wall -- I'm not a fan of this, but if it sounds better to your ears then it is better.

Most of us like multiple speakers though I'd rather have a single pair of speakers I really like rather than a lot of speakers that are less than great. I think surround sound is helpful in many cases. I'm never sure why some rooms seem to require surround and others don't.

Don't spend a lot on room treatment products until you've first tried cheaper substitutes like pillows, blankets, and upholstered furniture in corners of the room. Foam isn't expensive until it gets made into an audiophile product. More ideas??

Scott -

I guess it depends what you are looking to achieve. If you are using a wet sample set then I would suggest you want the acoustics as dead as possible and therefore a reverberate space is not going to work. Hence room treatment is employed including bass traps to absorb the sound. Dry sample sets rely on the room to add the acoustics, and then it gets complicated. Having lots of flat hard surfaces can contribute to a great acoustics but I'm sure you'll appreciate that there is a lot of complexity and science behind getting this right - a room needs to be designed, in terms of both plan and material, based on how the sound is going to bounce around the surfaces.

Kind regards,

James

When I was young, 50 years ago, I was always told by Hi Fi experts to put my speakers
in the corners of a room as the walls would act as a horn, amplify the sound and improve bass
response.

I am sure this advice was good then, but is it still a good idea?

csw900

Thanks James, but I don't quite know what I can achieve. All I ever knew was to set up your speakers facing forward against the wall, but it seems that (as csw900 noted) even that is wrong. Recently, I tried placing my speakers on my organ table and the difference was great. Much more bass, but hard on my ears when I played. So I tried turning them out 45 degrees to bounce off of the walls. Now the bass is even lower, the sound is clearer to me when playing, and also in the house when music or radio is played!

Sometimes the bass is just overwhelming though, even with 16 ft. stops. The Subbass 16' on the Rotterdam set, for example, sounds like the Sante Fe Super Chief is blasting through rattling everything around (and not in a good way)! 32 footers and resultants are in the "forget-about-it" drawer.

Perhaps this house is not built for such low notes, or perhaps there is something simple I can try that will reduce the 'earthquake syndrome'. I just don't know.

~Scott

Hi Scott,

I'd say I'm not convinced just yet from what you describe that room treatment is your answer and a few simple steps without any investment other than your time may make a big difference.

A better picture of your audio arrangement, audio routing and so on would help, and couple of things I'd ask: How many channels of audio are you using? How are you routing your audio (i.e. are you using one of the cyclic options within Hauptwerk, choosing your own routing configuration, etc.)? How many / type / size of speakers / sub(s) etc.,? Where are all your speakers currently placed? Do you use surround, do you have rear surround speakers and so on?

Marc

Thanks James, but I don't quite know what I can achieve. All I ever knew was to set up your speakers facing forward against the wall, but it seems that (as csw900 noted) even that is wrong. Recently, I tried placing my speakers on my organ table and the difference was great. Much more bass, but hard on my ears when I played. So I tried turning them out 45 degrees to bounce off of the walls. Now the bass is even lower, the sound is clearer to me when playing, and also in the house when music or radio is played!

Sometimes the bass is just overwhelming though, even with 16 ft. stops. The Subbass 16' on the Rotterdam set, for example, sounds like the Sante Fe Super Chief is blasting through rattling everything around (and not in a good way)! 32 footers and resultants are in the "forget-about-it" drawer.

Perhaps this house is not built for such low notes, or perhaps there is something simple I can try that will reduce the 'earthquake syndrome'. I just don't know.

~Scott

Scott,
I have a PDF of the M-Audio monitor setup in graphic magazine format. Send me your email and I will forward it to you. It is no longer available from M-Audio. It is a good place to start for setting up speakers for listening at the console.

A couple of really simple things you may not have tried. Don't put the sub in a corner but on a wall, in the middle of the wall and on the floor. Roll off the high side of the sub-woofer (most have a control to set the high end roll off to somewhere between 50-200Hz) to just at or slightly below the rated low end of the regular speakers. This keeps the subs from boosting bass you already have from the speakers. If the speakers go below the subwoofer no matter what you do, it may be necessary to add Reaper and a software equalizer to the Reaper FX which will act as an electronic crossover. The speakers should be raised to ear level of the organist off the floor using shelves or stands. Stands work better because you can get them away from the walls more. The lines between organist and the front speakers should form an equilateral triangle with the speakers pointed forward. Then you should download TrueAUDIO RTA https://trueaudio.com/rta_down.htm and a microphone from Parts Express to see where the peaks and nulls are in the room spectrum. Then adjust the Hauptwerk sample set from there. There are some home theatre room curves to use as a standard.

Best regards,

Thomas

Using a microphone to feed a spectrum analyser is a very interesting method of investigating
room acoustics which I have not come across before.

However for any kind of investigation of this nature I think you will need to use a "white noise"
signal source otherwise all you will find are standing waves set up by the particular note you
play -- and surveying these waves will not be very useful because there is not much you can
do to reduce of remove them.

Any room of any shape will have standing waves set up at particular resonant frequencies,
made worse by hard surfaces. I think this just has to be accepted unless you want to play
your music in an anechoic chamber or outdoors. This is called room colourisation.

Even in large rooms -- e.g. Cathedral there are often low notes that the organist dare not play
because the resonance can threaten to damage the structure of the building.

csw900

Scott, your "Santa Fe Super Chief" may be the result of standing waves, ie, the length of the sound waves for some notes or ranges of notes are nearly the same as or are multiples of dimensions in your playing space. The consequent effect is some notes sound much louder than nearby notes of just slightly different frequencies. As the sound waves reflect and bounce around your room, some are in effect amplified at least to the volume a listener perceives.

For example, in my living/music room, the D with frequency around 70 hertz has a wavelength of about 15', about the width of the room and about 1/2 the ceiling height. That note "booms" compared to, say, the F just above it or the B just below, both on my keyboard/synthesizer and all of my Hauptwerk sample sets. I correct it for the synthesizer with a hardware device, and with Hauptwerk with the voicing feature.

For Hauptwerk, I simply play notes up and down the scale for each rank and reduce volume for offending notes (and adjust brightness, etc as needed) to smooth out the perceived volume levels. Takes just a little time but is not difficult, and makes the difference between having something intolerable to something beautiful. I mostly have to adjust lower notes of 8' ranks, and more of 16' ranks, but I run through all ranks from top notes to bottom because there are some annoying perceived volume issues at other frequencies as well.

Barry

Edit: I posted just while csw900 was also pointing out the potential issue of standing waves. I also balanced all of my speaker volumes using an inexpensive sound level meter before playing anything "real", and was surprised by what I thought were correct levels versus what the meter was actually measuring. I used "pink noise" samples I found on the net, but have no clue how pink differs from white! The greatest difference between my perception and actual measurement was for my subwoofer, and corrections to it made the most improvement in getting the proper, good-sounding balance among ranks/notes.

Using a microphone to feed a spectrum analyser is a very interesting method of investigating
room acoustics which I have not come across before.

However for any kind of investigation of this nature I think you will need to use a "white noise"
signal source otherwise all you will find are standing waves set up by the particular note you
play -- and surveying these waves will not be very useful because there is not much you can
do to reduce of remove them.

Any room of any shape will have standing waves set up at particular resonant frequencies,
made worse by hard surfaces. I think this just has to be accepted unless you want to play
your music in an anechoic chamber or outdoors. This is called room colourisation.

Even in large rooms -- e.g. Cathedral there are often low notes that the organist dare not play
because the resonance can threaten to damage the structure of the building.

csw900

Sure you can. One of the Hauptwerk pipe voicing parameters is SPL so you reduce the level so that pipe matches the others.

First, a disclaimer. I am not an expert and am not recommending this approach, and have no connection with the supplier mentioned below (other than the fact that I have one of their subs) however ...

I believe that the first thing you should correct if you are making a home sound studio are the room characteristics. You can do this with sound damping panels and with, so-called, bass traps.

The problem is that organ sounds have very low frequencies and that room treatments tend to have little effect at these wavelengths. Basically, the thickness of the treatment is a function of the wavelength you want to subdue.

So for low frequencies you could use a system like this: http://www.bkelec.com/HiFi/Sub_Woofers/ ... de--DC.htm The system is a bit like an electronically-controlled graphic equaliser. The first step is to play noise into the room while the system is "listening" via a microphone. It knows what the spectrum of the noise looks like and it also knows from the microphone output where the room peaks are. It then sets itself to remove those peaks using dynamic filtering.

Regards,