A simple trick to clean up the sound of your audio system

[JohnnyB]

Over the years I'd heard that it wasn't a good idea to have other speakers or guitar or bass combo amps in your audio listening room. The theory was that the speakers of the instrument amps could absorb the sound waves of your stereo, sucking the dynamics out of the music, or conversely, absorb the waves into the cabinet and then release them into the room, smearing the sound and overloading the room with the resonant frequencies of the speaker cabinets.

After living for 3 years with an Eden 2x10 3.6 cu. ft. bass combo amp in my living room, I decided to put the theory to the test and wheeled the amp out to another room and fired up the stereo to see if I heard an improvement. Eureka! The improvement in sound exceeded my most optimistic expectations. It was as if I'd made a $1,000 upgrade at least, whether in room treatments, better speakers, or better amp and speakers.

Basically, it squelched my suspicion that I'd bought too little speaker for my listening area. Gone was the congestion and upper bass overload I had been hearing at medium-high volumes. Tthe entire presentation at every volume became much more clear and musical. Presentation was more linear with no noticeable lumps, and the soundstage became 3-dimensional as I'd never heard it in my room before. Now I can let this system rip as I couldn't before. I've been playing large scale orchestral and big band all week and hearing very familiar pieces with new levels of dynamics, smoothness, low level detail, and 3-dimensional imaging. There's a new ease and relaxation to the music that I hadn't had before, and when things get loud the music still stays clear. I'm finding that these speakers are even better than I'd realized. At their current price of $800/pair they are a stone cold bargain. Given that these used to sell for $2500 i can confidently say you simply can't do better at that price. I also did a sanity check. I was playing a Count Basie record of small band swing--a septet. I brought my wife in to listen and she immediately noticed that she could hear the musicians' breaths behind the saxes and horns they were blowing. She'd never noticed it before.

I know that many of you have your amps and guitars in the same room as your audio gear. That's what I was doing too, and I get a lot of good out of playing along with recordings. It stands to reason that the effect of removing a guitar or bass amp will vary according to the size of the cab and speaker array relative to the room it's in as well as its position in the room. You may not hear a difference removing a Fender Champ or Princeton. But if it's a 2x12, half stack, or bass combo placed along the wall, I suspect it will consistently thwart efforts to tune the room. It may also depend on the cab configuration. I had a 2x12 open back guitar amp for a long time and didn't have the problem I did with the bass amp with enclosed but ported cab. YMMV.

Still, given the amount of improvement I got just by schlepping the combo amp out of the room, I recommend you try it. You may find it useful when you want to do some critical listening or playback for mixdown.

[gorch]

As a consequence, the recommendation were to have only one amp-speaker system per room. Never place a Fender in the same room to a Vox and/or Marshall system, whatever combination of amps and stereo system you have in the house. JohnnyB, I'm not quite convinced it requires this amount of consequence. Typically, I would have furniture in my living room that naturaly dampens frequences too.

Surely, a 2nd speaker would to some extent reflect airwaves produced by another speaker, simply because the speaker has a moving membran. However, I would expect that it requires a certain amount of volume to have a noticable effect. Did you think of a psychological listening effect? Or would you say the room size makes a difference?

[hamerhead]

JB, you know I love ya man. You've never steered me wrong. And I wish I had your ears. But wouldn't anything with the ability to vibrate have a negative (or positive) effect on sound? I mean unless your house and everything in it is granite, aren't all these vibrations being bounced or absorbed - somehow altered - by something anyway? I understand that a speaker may do that more dramatically and have a greater effect, but as Gorch said, a chair, coffee table, or bookcase should also have an effect, no?

The condition of my ears would never allow me to be an audiophile. I think there's a fair number of people - Johnny's one of 'em - who can actually hear with an audiophile's ear, but also an equal number who are just plain full of sh!t. I'm jealous of those who have it, and loath the over-the-top assbags who can hear a speck of fly shit on one of their cables from 40 paces.

I'll keep in mind to roll the amps and speakers out the next time I'm mixing in the guitar room. It's not a high-end set up, but I'd bet it can't hurt. But I'm NOT moving all those frickin' guitars. No way.

Thanks, JB.

[tomteriffic]

Compared to John, I'm a cloth-eared idiot, but...

There's some science underneath this. While something with an open back, higher cabinet tuning, stiffer cone suspension, etc. might not react with a room in the way Johnny describes, it's quite possible that a bass amp, especially one like the Nemesis with a tuned enclosure and compliant speaker suspension would react this way. Typically middle and higher frequencies out in a room don't pack enough acoustic energy to get a guitar cabinet/speaker to react in a significant way.

But lower frequencies do pack significantly more energy and if they encounter something like a bass cabinet, the speaker and/or cabinet can resonate sympathetically with the frequencies it's being hit with. The results can be unpredictable, much like having to move a subwoofer around a couple of inches at a time to get the most even response.out of it. The bass cabinet could reinforce some frequencies, suck out others, and, I would assume, cause some pretty big resonances in some frequency ranges and cause other frequencies to virtually disappear. Those long bass wavelengths can do some pretty weird stuff.

Just for those who might be inclined to look into it, the magic words to Google are Helmholtz Resonator. That's what John had going on in his listening room.

P.S. I'm still keeping an eye out for that particular model of Nemesis. It's the best damn "not a refrigerator" sized bass amp I've ever heard.

[JohnnyB]

While something with an open back, higher cabinet tuning, stiffer cone suspension, etc. might not react with a room in the way Johnny describes, it's quite possible that a bass amp, especially one like the Nemesis with a tuned enclosure and compliant speaker suspension would react this way. Typically middle and higher frequencies out in a room don't pack enough acoustic energy to get a guitar cabinet/speaker to react in a significant way.

But lower frequencies do pack significantly more energy and if they encounter something like a bass cabinet, the speaker and/or cabinet can resonate sympathetically with the frequencies it's being hit with. The results can be unpredictable, much like having to move a subwoofer around a couple of inches at a time to get the most even response.out of it. The bass cabinet could reinforce some frequencies, suck out others, and, I would assume, cause some pretty big resonances in some frequency ranges and cause other frequencies to virtually disappear. Those long bass wavelengths can do some pretty weird stuff.

EXACTLY! My bass amp has a large port at the bottom of the front baffle. The speakers have very light (aluminum?) diaphragms with very compliant suspensions and the enclosure is a 3.6 cu. ft ported box, 2-4 times the volume of most stereo speakers, so it can suck up a lot of sound. It's well known that low frequencies travel along room boundaries. The wide-diameter port is at floor level going into that big cab, where it can then activate the two highly compliant 10" drivers to regurgitate certain frequencies back into the room, most likely the fundamental resonance of the cabinet/speaker assembly.

OTOH, before I had the Nemesis, I had a Mesa/Boogie DC-10, 100w open back 2x12 combo. I didn't notice any/much interference with it. I suspect it's because the heavy duty speakers weren't all that compliant, and being open-backed, there was no fundamental enclosure resonance and the soundwaves of the stereo were hitting both sides of the speaker diaphragms with equal pressure, so they didn't set them in motion much.

A sealed cab half stack or stack will probably suck some of the dynamics out of the room, but not add the big resonant time smear that my bass amp did, because there's no port of entry into the cabinet. A Thiele aligned cabinet (ported or slot ported) will act more like my bass amp did. A Princeton or Deluxe won't have much effect. I have a vibraphone right next to my right speaker. It has three chromatic octaves of resonator pipes. I suspect I'd get a little improvement if I moved it out of the listening room but I'm not going to. But moving the bass amp, that was a significant improvement. It didn't take golden ears to hear the difference. Before, the stereo sounded like it was playing underwater when the volume got to a certain point. Now it can get loud and still sound natural.

Now, as to the other things Gorch and Hamerhead brought up, the answer is yes. The room and its furnishings are the most influential component in any home sound system. Every wall surface, table surface, wall hanging, window, window treatment, etc. reflects, absorbs, and/or resonates. In most cases all these things even out, spreading out the resonances and reflections in a random scatter. But there are some elements that can have a significant effect, and a ported speaker cab with very responsive diaphragms is one of the poster boys for this phenomenon.

Here's a question--have you ever gone to a stereo store to audition speakers and they take you to a room full of speakers hooked up to a switchbox so you can listen to a selection of speaker pairs at the touch of a button? Have you noticed that all of them sound like ass--flat, undynamic, uninvolving, nothing sounding too exciting? I sure do. It's all those diaphragms moving in sympathy with the sound coming from the main speakers, absorbing dynamics and obscuring definition. Plus, almost all audio speakers today are ported, so they can all act as Helmholtz resonators at multiple frequencies, most at mid-bass frequencies.

P.S. I'm still keeping an eye out for that particular model of Nemesis. It's the best damn "not a refrigerator" sized bass amp I've ever heard.

No argument here. I still can't believe how good it sounds. Not only does it tell you exactly what's happening upstream with your pickups, setup, string selection and even instrument cord, but it is somehow unfailingly musical and articulate no matter what. I traded my used Mesa DC-10 even up for a new floor demo Nemesis. And I had gotten that Mesa at a pawn shop for $299, so I'm not complaining.

[zenmindbeginner]

It was as if I'd made a $1,000 upgrade at least

At their current price of $800/pair they are a stone cold bargain.

Given that these used to sell for $2500

I don't want to be the one to point out the glaringly obvious here but...

Has any of this been adjusted for inflation?

You are the quintessential and consummate renaissance man JohnnyB, your attention to detail is always challenging and inspiring.

Now check out how fierce King Tut can be on the runway.

[django49]

Now that you mention it, I notice that when my wife is in the room while there is music playing (or the TV for that matter) there tends to be sound emanating from her that interferes with the enjoyment of the source music. (Even more so when her sister joins us). I guess I need to ask her to sit on the subwoofer and see if the low vibrations have any impact upon her frequency response.

[Toadroller]

Now check out how fierce King Tut can be on the runway.

"I'm on a horse"

But yes, the drivers could absorb at resonant frequencies and reflect at others. I haven't hooked up my "good" stereo equipment in 3-4 years (The Snell B Minors sit and wait in a corner, covered with an afgan), but the critical listening sessions will have to wait and wait. If until we're empty nesters, a long wait. The youngest is three.

[JohnnyB]

But yes, the drivers could absorb at resonant frequencies and reflect at others. I haven't hooked up my "good" stereo equipment in 3-4 years (The Snell B Minors sit and wait in a corner, covered with an afgan), but the critical listening sessions will have to wait and wait. If until we're empty nesters, a long wait. The youngest is three.

There's no reason to forgo good sound at home because you have young children. It does influence your choice of gear, however. I bought a brand new pair of floorstanding loudspeakers and my first CD player when my daughter was 2 months old. I upgraded my amp and then speakers when my son was 5.

The speakers I bought just after my daughter was born was a pair of ADS L1090s. Unfortunately ADS is out of business now, but they made great-sounding speakers and they were well-suited to homes with young kids. The grills were perforated steel, so little fingers couldn't poke holes in grill cloth or dents in the speaker diaphragms. They were sealed enclosures so there were no ports for stuffing Legos, Barbie purses, and other little things that toddlers stuff in the oddest places. I added plinths to make the tall narrow towers more stable and less likely to be tipped over.

Things you want to avoid with little kids are stand-mounted speakers and tube electronics. They can pull on the speaker cable and bring the speaker right down on their heads. And they could burn themselves on tube amps. I wouldn't want something as fragile as a turntable tonearm and cartridge anywhere near curious little hands, so you could isolate the turntable or make do with a CD player or (better) server-based digital music.

Having a good music system is also a way to introduce your children to the joys of music at a very young age. I remember when my daughter was going on three when I was playing a CD of Vivaldi's "The Four Seasons." She was taking a bath and from the bathroom I could hear her say, "Is that Beebaldi? I LIKE Beebaldi!" Another time we were sitting on the couch while album rock was playing from the FM tuner. She suddenly started exclaiming, "Stilly Dan! Stilly Dan!" She was close; it was a cut from Donald Fagen's "Nightfly" album. She made the connection from hearing me play Aja and Steely Dan's Greatest Hits.

[gorch]

...

EXACTLY! My bass amp has a large port at the bottom of the front baffle. The speakers have very light (aluminum?) diaphragms with very compliant suspensions and the enclosure is a 3.6 cu. ft ported box, 2-4 times the volume of most stereo speakers, so it can suck up a lot of sound. It's well known that low frequencies travel along room boundaries. The wide-diameter port is at floor level going into that big cab, where it can then activate the two highly compliant 10" drivers to regurgitate certain frequencies back into the room, most likely the fundamental resonance of the cabinet/speaker assembly.

...

More a fun thing. The moving speakers should be able to induce a signal. It would be interesting to record this and play with the results for a song concept.

Here's a question--have you ever gone to a stereo store to audition speakers and they take you to a room full of speakers hooked up to a switchbox so you can listen to a selection of speaker pairs at the touch of a button? Have you noticed that all of them sound like ass--flat, undynamic, uninvolving, nothing sounding too exciting? I sure do...

Me too and I agree until I heard the Ohm L sometime in the mid 80s. Those were not just outstanding in the audition environment, they were outstanding in the room too. And still are as the cabinets stood the time and children and I had refurbished them 3 or 4 years ago and again enjoy.

[hamerhead]

Now that you mention it, I notice that when my wife is in the room while there is music playing (or the TV for that matter) there tends to be sound emanating from her that interferes with the enjoyment of the source music. (Even more so when her sister joins us). I guess I need to ask her to sit on the subwoofer and see if the low vibrations have any impact upon her frequency response.

And I'd bet she's a helluva lot harder to move out of the room, too. With a wife and 2 daughters, I feel your pain.

Let us know how that subwoofer thing works out.

[JohnnyB]

Now that you mention it, I notice that when my wife is in the room while there is music playing (or the TV for that matter) there tends to be sound emanating from her that interferes with the enjoyment of the source music. (Even more so when her sister joins us). I guess I need to ask her to sit on the subwoofer and see if the low vibrations have any impact upon her frequency response.

And I'd bet she's a helluva lot harder to move out of the room, too. With a wife and 2 daughters, I feel your pain.

Let us know how that subwoofer thing works out.

You can probably get her out of the room in no time by playing some '70s fusion and cranking it.

[Bobby Marshall]

So if I have long curtains in the room won't that negatively impact sound quality as well? Big soft sofas and chairs? Where do you draw the line between luxury and sound quality?

[JohnnyB]

So if I have long curtains in the room won't that negatively impact sound quality as well? Big soft sofas and chairs? Where do you draw the line between luxury and sound quality?

You draw the line at whatever doesn't bother you or you're willing to live with. As mentioned before, everything reflects, absorbs, and/or resonates. Most of it is benign, however, as the combination of book and record shelves, throw rugs, bare walls, windows, drapes, pictures, wall hangings, and hard and soft furniture creates the "average listening environment." Think about a night club or concert venue, especially a concert hall. It's also a combination of hard and soft surfaces, bare floors, carpet, wall hangings, and room shape irregularities. Sound absorption also goes up as the audience files in and take their seats. Most of these things average out to a typical indoor listening environment, which reflects and absorbs sound as we're accustomed to it.

What I'm talking about are the few high-impact anomalies. My bass amp, for reasons Tom explained earlier, is one of them. A cushy couch by itself is not. Sitting compact speakers directly on a big wood surface (shelf, table, etc.) makes for a big surface bounce. Elevating the speakers and putting them on Auralex pads will minimize that. If your room has large overstuffed furniture and thick wall-to-wall carpet and tapestries covering every wall, and thick heavy drapes, it is probably overdamped. You'll notice you have to turn your system up more for it to sound exciting and the treble will consistently sound rolled off, muffled even. If you have all bare floors, bare walls, all hardwood furniture, and large uncovered windows, your room is probably too reflective. Sound will be harsh and bright. Crescendos will make you wince. So it's all a question of balance. We're not trying to eliminate all reflections and resonances here. We want a randomly scattered balance of hard and soft surfaces. And we want to be able to identify big resonances, such as if your room is 12'x12', which means it will strongly reinforce the sound when it hits 94 Hz, whose wavelength is almost exactly 12 feet.

Incidentally, I figured out that all I have to do is tip my bass amp forward on its front to block the port and speaker diaphragms. When I want to play I just tip it back up. This wouldn't be practical for a 4x12 half stack. But you could get a piece of foam core poster board and cut it to fit the front grille to block the speakers and port when cranking the stereo. The board is light and easy to handle. Just toss it behind the speaker cab when playing it.

When I had a Mesa DC-10 in the same spot in the room, I didn't have this problem. It just doesn't resonate and overpower the room the way the Eden amp does. I wouldn't change a thing if we're talking about an open back 1x12.