DSP vs. GIK Treatment in 12.5x17.5 Room???

529proaudio · « **on:** 12 Oct 2020, 03:07 pm »

I realize these aren't mutually exclusive, but what is the consensus on active DSP room-correction versus GIK bass traps in a relatively small room measuring 12.5' wide by 17.5' deep with a vaulted ceiling that goes from 8' to approx. 12' at the peak? GIK recommended stuffing the room with as many bass traps as I can, but I've also read comments suggesting that there is no way passive bass traps can solve low-end frequency response in a small room. I've never considered DSP as my rig is primarily analog, but I'm willing to give it a shot...especially if it is only correcting the sub. But I've also read that one should fix as much as possible with acoustic panels and reserve DSP for minor adjustments.

System consists of KEF LS50 Meta speakers with a single REL T/9i sub along the short wall. Running a VPI Prime through all Don Sachs gear: tube phonostage, Preamp 2, and Kootenay 120 power amp. It sounds good as-is, but I would like to get a little more depth and realism to the soundstage.

I just got a UMIK-1 and can run some sweeps in REW with and without the sub if that helps, but according to GIK the files are just going to tell me I need to absorb the low-end as much as possible. I just don't want to spent $1k on GIK panels only to find out that the impact is minimal--return shipping would be cost prohibitive, plus they are backordered 2 months right now.

Best,
Chris

blownrx7 · « **Reply #1 on:** 12 Oct 2020, 03:59 pm »

Here's my experience and I make no claims this is the only solution, but...
I have both digital correction and traps in my present room. While the traps help, they did not solve the bass issue in my room. Digital did it with one click. I started with REW myself and loved the results but hated the time required to get right and sensed the signal degradation as minimal as it was. I then went to Dspeaker Anti-mode 2.0 and now X4 and LOVE the ease of setting, modifying and minimal signal degradation. You can get the Anti-mode 2.0 for the price of a few traps!
While I would have MUCH preferred just traps and left the signal unmolested, I just could not get there. You have to turn the room into a virtual anechoic chamber with traps all over the place to get the bass response under control in any room especially a smaller room. Besides spending a mint on traps, absorbers and diffusers, the room gets taken over by them and the WAF is ZERO. Actually, my wife is extremely accepting of my hobby, but I couldn't stand the traps all over the place.
So, I agree, traps to reduce the issue but digital to correct it once and for all.

529proaudio · « **Reply #2 on:** 12 Oct 2020, 04:33 pm »

Thank you, this is exactly the type of experience I’m keen to hear about! And, yes, my wife is also very understanding, but we just don’t have the room to do much in the way of monster 8” bass traps as suggested by GIK.

When you mention signal degradation via REW, do you mean the DIRAC DSP solutions?

blownrx7 · « **Reply #3 on:** 12 Oct 2020, 09:24 pm »

Quote from: 529proaudio on 12 Oct 2020, 04:33 pm

Thank you, this is exactly the type of experience I’m keen to hear about! And, yes, my wife is also very understanding, but we just don’t have the room to do much in the way of monster 8” bass traps as suggested by GIK.

When you mention signal degradation via REW, do you mean the DIRAC DSP solutions?

No, I was using a Behringer.

Mike-48 · « **Reply #4 on:** 13 Oct 2020, 05:24 am »

I'm using both DSP and acoustic treatment myself. I think you've gotten some good advice so far. I'll add this: It's almost impossible to control bass under 100 Hz with traps. They would just have to be too big. For example, if you look at GIK's graphs for their Monster Bass Traps, the absorption falls off the cliff below 80 Hz. So if you're trying to control bass, unless you have an astoundingly good room, you will need DSP.

But DSP in my experience works best when it has least to do. So you could add as many bass traps as you (and your mate) are comfortable with, and do the rest with DSP.

Or, you could try DSP first and see if you're satisfied. It's a lot easier to return a DSP unit if you don't like it than ship back some humongous bass traps.

Depending on budget, you could try the Anthem STR Preamp or the miniDSP SHD. Both are recent units -- and I think DSP has improved recently.

JLM · « **Reply #5 on:** 13 Oct 2020, 11:11 am »

Suggest reading Floyd Toole's "Sound Reproduction" 3rd edition. It's the consummate audiophile guide to learning how loudspeakers and subwoofers behave in-room. In it you'll learn:

1.) Bass peaks/dips are inherent to residentially sized rooms (room shape/size makes huge differences).
2.) Best first step (after designing your room) is to pick the "right" loudspeakers, KEF LS50 meta aren't bad.
3.) Next use of multiple subwoofers (he recommends 4, one per corner or along middle of each wall), side-by-side with the mains is a horrible setup).
4.) Then add bass traps (absorption). Realize that vendors will oversell anything.
5.) Finally, and only as icing on the cake, try room EQ. Earl Geddes, another respected acoustician, says to solve physical problems by physical means (subwoofers and bass traps). EQ can only "artificially treat" a single location in the room. Think of squeezing a balloon, you can change the shape but not the volume).

I started with an ideal room shape, following Fibonacci ratios (8ft x 13ft x 21ft). Next I added 3 subwoofers (3 was sufficient as per discussion with Geddes or Toole's 1st edition). Then added 4 2ft x 4ft GIK 244 bass traps straddling the front corners. Finally tweaked with Behringer DEQ 2496 (hard to use the out dated version of miniDSP SHD), then a DSPeaker Anti-Mode 2.0 Dual Core (tiny screen, back panel, remote), then Dirac (which was much easier to use).

Surprised GIK wasn't more honest with you regarding the benefits of REW. From your account it appears that they dismissed it's ability to adjust the loudspeaker/room response. I've found GIK panels to be highly effective in less than ideal rooms, much less so in my room. Not a believer as stated above in turning the room into an over dampened anechoic chamber although I have a total of ten GIK panels in my dedicated room, six full range 244's and four range limited 244's. (Roughly 2/3rds of what we hear is reflected sound.)

Think of REW as the more powerful, harder to use, freeware version of Dirac. Both are room EQ measuring/adjustment softwares. Knowledgable folks recommend limiting use of DSP to bass frequencies (below the transition/Schroeder frequency, roughly 300 Hz - room dependent). Above that you'd be affecting the sound of your chosen loudspeakers. I'm limiting my Dirac to 210 Hz as frequency response above that is quite even.

Realize that diffusion can only be effective for higher frequencies as it works based on the size of sound waves. Length of sound waves is speed of sound (13,500 inches per second) divided by the given frequency. So a 15,000 Hz signal is 0.9 inches long and a 1,100 Hz signal is 12.2 inches long. So a 7.5 inch deep diffuser (the deepest commercially available ones) can only treat down to 900 Hz.

529proaudio · « **Reply #6 on:** 14 Oct 2020, 12:09 am »

Thanks everyone for the thoughtful replies. I’m pretty hamstrung by my room options, so I can’t do a DEBRA/SWARM array in here any more than I can install ten 244 panels. I think I can get away with one 23” tri-trap in one corner and a 36” tri-trap in the other, and possibly a few 244 panels on the front wall as well as a small 1x1 panel for the first reflections on either side, but that’s about it. If that isn’t going to move the needle, then I would really rather not spend the $1k. I may try some DSP on the sub to see how much of the low end I can smooth out, and if that proves successful I’ll add some GIK panels to take it one step further. Happy to post a screenshot from REW if that helps?

jtcf · « **Reply #7 on:** 14 Oct 2020, 03:11 pm »

You can't trap the long bass waves,but you can smooth them and stop the velocity and reflection of the waves that are the approx length,height, and width of your room,also the half waves.Straddling the corners with 244s,especially the ceiling/wall junctions on the front wall (behind the system) is very effective. First reflection treatments are for higher frequencies. A panel front and center and one on the back wall will kill mid and high reflections. A ceiling cloud centered between you and the speakers is a consideration. You could get some rock wool panels at a hardware store inexpensively and experiment. Just a suggestion if you feel like giving it a try:-)
I bought a package of ten panels from GIK and spent a week moving them here and there. What I found was their recommendations were entirely correct. Before I took the plunge I spent quite a while with foam mattress pads tacking them up and rolling them into *tube traps* and could hear small positive changes. I'm not affiliated at all, just wanted to share my experience. No experience with DSP,but I do have a
swarm of subs. My room is horrible and square but now it sounds really good.

Mike-48 · « **Reply #8 on:** 14 Oct 2020, 03:36 pm »

I'll repeat my suggestion that -- given YOUR situation -- I would try good DSP first. I would not try a cheap miniDSP unit, but rather something from their SHD line or perhaps an Anthem STR or DSPeaker X4. The fly in the ointment is that you are using tube equipment now, and the DSP gear will be solid state and digital, and that itself will give a change that you may or may find acceptable. So make sure you can return the item if you don't like it. (The other side of that coin is that it takes time to learn to use such units to best effect, so get a minimum 30 days' trial.)

The alternative, bass trapping in the corners and such, is always helpful, but it does not seem to meet your aesthetic needs, so it can be saved as Plan B. Likewise, if you don't have the space or tolerance for many boxes and wires required by a Swarm (distributed bass array) approach, it's understandable. I do not dispute the effectiveness of DBAs, which are terrific tools, but still, they are not the only way to address the issue.

The vaulted ceiling in your room should help reduce bass peaks. Yes, I would run sweeps with REW to find the speaker -- and sub -- positioning that best meets your objectives.

As background, I am not a dealer or audio professional. Just an audiophile who's been using DSP in my audio systems for over 15 years, and using acoustic treatments a bit longer than that.
I hope you get great results, whatever you choose!

GeorgeAb · « **Reply #9 on:** 15 Oct 2020, 10:13 pm »

I had a similar sized room and even with a couple grand in GIK panels and traps it did not put enough of a dent in boomey bass. Due to room had limited speaker placement options. DSP will be able to resolve your frequency response issues in the low end. Roon Lab's build in DSP is quite impressive and IMO worth the price of the software and that is only a small subset of what it does. Even a inexpensive Behringer DEQ2496 will do the trick. In my experience if you use in the digital domain between digital source and D/A converter, is more ideal then going A/D and D/A. I have used to great effect to get rid of boomey bass.

That said taming the frequency response is quite different then treating room reverberation (sound delay) that can only be treated with absorption. Necessary for tight focused sound with deep and wide soundstage. Also if you look at the GIK calculators for 10% minimal to 25% ideal coverage that is a lot of panels, square footage of treatment. My experience is to use most treatment in front of room rather than back to keep sound alive. Making your panels is 1/2 the price of store bought for similar material Rockwool "safe and sound" and Guilford of Maine covering.

I no longer have to use DSP in the low end (still use to get the sound I like which is close to the room curve targets), but I had to move to a significantly larger dedicated two channel room, where I had no limitation on speaker and subwoofer placement and could treat with ideal (25%) coverage; 10 bass traps and 19 2X4 panels.

Also, on speaker/subwoofer placement the application room sim inside of REW is such a time saver to find optimal placement for minimal room modes.

Keep us posted on your progress. Not easy stuff, but so so worthwhile.

Tyson · « **Reply #10 on:** 16 Oct 2020, 01:25 am »

Really difficult rooms is the reason I got into OB speakers - way, way easier to get great bass with an OB in a bad room.

firedog · « **Reply #11 on:** 16 Oct 2020, 07:01 am »

The best solution is obvioiusly both.

In my similar sized (even smaller) room bass traps made a big difference.
DRC made another, additional big difference.

If you are willing to try DRC, do that first. Maybe you will be happy with the result and game over.

REW is great; I spent the money on Audiolense, find it much easier to use and understand; more flexible.

Software DRC running on a PC can give you much more powerful and accurate RC than "devices" with RC built in - as they don't come with the computing chops a PC does. You are talking about orders of magnitude more computing power and often software designed to much more powerful calculations.

JLM · « **Reply #12 on:** 16 Oct 2020, 11:21 am »

So Chris, what is your sonic complaint(s) anyway?

Sorry, we've all put the cart ahead of the horse by jumping in without defining your problem(s).

BTW, can you provide a floor plan or at least describe your loudspeaker, subwoofer, listening locations?

Rob Babcock · « **Reply #13 on:** 18 Oct 2020, 08:22 am »

I like to do what I can with speaker position and room treatments, and then finish up with EQ. The Behringer is a great unit for not a lot of money, as a bass EQ at least.

Photon46 · « **Reply #14 on:** 19 Oct 2020, 01:25 pm »

I heard Eikon's audio/speaker system using DSP in an otherwise untreated hotel room (of roughly the size you describe) and it was VERY impressive in its ability to correct for acoustic anomalies. The bass control and accuracy was outstanding. The demo certainly made it apparent that it was possible to greatly overcome deleterious room effects with DSP only, at least in that particular room.

Mike-48 · « **Reply #15 on:** 19 Oct 2020, 06:11 pm »

With regard to the comment by @Photon46 --

I've heard the Eikon speakers, too, and thought they were quite good. This was at AXPONA 2019. The Eikons appear to use a DSP box similar to some of the Legacy speakers, a device made by Boehmer Audio in Sweden and based on wavelet theory. But I've heard great results from other DSP systems, too.

I'm definitely a DSP user, starting with a TacT 2.2X bought in early 2005. I think that, unless an audiophile has heard a really good DSP system, they may not realize just how effective such a system can be, even in a poor room.

That is not to dismiss the idea of improving room acoustics before applying DSP. I think that's the ideal road to take. What I'm saying is that the other road -- DSP alone -- can in many circumstances give very good results and shouldn't be dismissed out of hand.

P.S. To my mind, the biggest disadvantage of DSP is that its work tends to be position-specific, especially in the bass.

Big Red Machine · « **Reply #16 on:** 19 Oct 2020, 06:51 pm »

So PRO, where do you sit in the room? The room is the elephant in the room - ooooh, that's twisted.

Wherever the nulls and peaks lie need to be known so you can take advantage of or avoid.

My most recent room was very close to older room sizes but my only real solution was to move my chair after I got the best frequency response out of the speakers wrt side and rack walls. Then I improved my overall experience by moving back until everything came into focus.

I am leaning toward OB next year regardless of all the work with the box speakers I went through.

http://noaudiophile.com/speakercalc/

https://ethanwiner.com/basstrap_myths.htm

https://www.audiocircle.com/index.php?topic=166277.0

pompon · « **Reply #17 on:** 20 Oct 2020, 04:46 pm »

Somes good product like PureAudioProject, Spatial Audio, Tri-Arts Audio and Vrell Acoustics.

Quote from: Big Red Machine on 19 Oct 2020, 06:51 pm

I am leaning toward OB next year regardless of all the work with the box speakers I went through.

Likesmusic · « **Reply #18 on:** 24 Mar 2021, 07:36 pm »

I see that this thread is a tad old but I will add my opinion for reference in case some one else stumbles upon this in the future.

Personally I am a big fan of electronic room treatment. A good analog e.q. like the Klark-Teknik DN360 can solve a lot of problems by itself when integrating a system to a room.

I have tried to integrate a sub into a room and a system without an external crossover and I will never do that again. The addition of an external DSP made the task so much easier not to mention the improvement in system performance. External analog crossovers are still being made but a DSP unit can do so much more. My preferred DSP is an XTA DP448

I am also a fan of multiple subs.

I probably should mention that my room is 10 x 14 x 9 and I use 4 subs (2 different sizes and 3 different brands) paired with a set of book shelf speakers. Nothing is in its optimal location due to room constraints. The subs are located wherever I had room to put them to keep them out of the way. There is variation in bass response but overall it is quite smooth through out the room.

My plan is to investigate room treatments in a couple of years or so, though I will probably invest in some heavy drapes for the windows later this year. I’m not sure how much value I will get from treatments so I am hoping to find something that I can use on a trial basis. My guess is I will get some improvement with reflections but I see no need for bass traps at all.

529proaudio · « **Reply #19 on:** 21 May 2021, 03:12 pm »

Sorry for the very late reply, but this was about the time I threw in the towel and sold off my system. I had invested a ton of money and just couldn't seem to find a good location in my home commensurate with the quality of gear. Many great solutions about acoustic treatment, but my wife would have killed me if I decorated our bedroom or living room in tons of acoustic panels.

Fast forward to today, and I'm happy to say I'm getting far better sound in this room than I ever got with my old system costing 5x as much. Where did I land?

1. NAD M10 w/ DIRAC (snagged a new dealer demo for $1500)
2. ELAC Uni-Fi 2.0 Bookshelf Speakers ($600 new)
3. Technics SL-1500C running a stock MM Red cart through a Schiit Mani phonostage ($1100 new)

Contrast this humble set-up with my old $$$ rig:
1. Don Sachs Line Stage ($3k)
2. Don Sachs Kootenay KT88 Power Amp ($4k)
3. VPI Prime w/ HW-40 Feet and Hana SL MC cart ($4k)
4. Bob's Devices SKY20 SUT feeding a Don Sachs Tube Phonostage ($3k)
5. Tannoy XT 8F floor standing speakers ($2k)
6. Stereo REL T/9x subs ($3k)

Of course, this isn't to say that any of the brands listed above are not superior, but I've finally come to the sobering realization that what ultimately matters is not the gear but rather how the gear sounds in the ROOM.

My original plan was to order some Spatial Audio OB speakers from Clayton and just use the ELACs in the interim while I waited on a set of Spatials. Now, I'm not so sure as these stupefyingly cheap speakers are just insanely good. The NAD M10 class-D amp pairs amazingly well with them. At 100wpc, it has just enough power for the inefficient design, providing great dynamics, stereo separation, low-end extension, detail and sound staging. The speakers are easily placed in my room with the port moving to the front of the cabinet on the 2.0 revision. Very easy to get the speakers to disappear.

I'm still experimenting with the built-in DIRAC capability using both the NAD measurement microphone and a Umik-1. I'm not a fan of the DSP on the full-frequency range, but it seems to work incredibly well on the low-end where I obviously have some room modes. It effectively reduces the low-end boom, thus improving clarity, especially on vocals. The instructions are pretty vague about how to take the measurements, so I bought a laser measuring device to ensure I was placing the microphone accurately when taking the various measurements.

My old system was pretty much analog-only, so I'm really loving the ability to toggle between vinyl and Tidal. Both sound wonderful to my ears, but I think the vinyl still has the edge, at least on my best-sounding records.

Speaking of which, I'll just say that the Technics SL-1500C direct drive table is an amazing value. Speed accuracy is far better than my belt-driven VPI Prime, and if it sounds this great with an MM Red, I'm dying to hear what it can do with a higher-end cart, which will probably be my next upgrade. Leaning toward a Soundsmith high-output cart, i.e. Zephyr Mk. III ES or Aida ES.

I'm still considering a modest investment in some GIK treatment to complement the DIRAC DSP, but I'll always be limited in that regard as this is my master bedroom. At most I would be adding a 3 ft. high corner trap and a 23" high demi-trap, both on the left side as I have doorways in the two right corners, and a 24x48 art panel on the rear wall.

On a final note, my wife is absolutely loving the system in its present location. Win win!

Best,
Chris