Getting good sound quality below 200Hz

I run open baffles with currently 15" Eminence Alpha bass drivers with their dedicated Rotel amp and crossed over at 200Hz with 24db slope.

This underpins the upper driver beautifully but by contrast if I play it on its own its not at all impressive, lacking primarily in both definition around the sounds and also impact.

My first question "is this typical of what sound is like below 200Hz"

Secondly looking to improve this should I concentrate on improving the 15"drivers or the amp?


Please don’t recommend a powered sub as I have one already which will eventually underpin the 15"drivers when I have that bit right.



Not sure bass should sound impressive as opposed to natural.  Also depending on the instrument much of the definition and possible impact are conveyed by the harmonics reaching into the midrange frequencies.

This underpins the upper driver beautifully but by contrast if I play it on its own its not at all impressive,


What exactly does this mean?  You play the 15" without the mid/highs?

Get measurements.  What might be happening is that you have peaks which prevent you from turning them up high enough.  Try to get a descending slope from 20 Hz or so to 200. 

Yes it means exactly what you said. The midrange is disconnected and the 15" drivers play on their own without changing volume setting. The volume is never excessive.

I have no idea if it sounds natural as I have never experienced music played below 200 Hz - hence the question.



Measurements are your friend here. :)  I encourage you to find a way either via Room EQ Wizard and a calibrated mic or otherwise to see what's going on.

Good suggestion, but I would still like to know of others listening experiences to just the frequencies below 200 Hz. Surely I'm not the only person to have done this.


I'd say that no, this is not necessarily typical of bass below 200 Hz. 

But, I think you might begin to get a more insightful frame of reference here, if you simply, say, try a different set of woofers to experiment with. Eminence woofers are relatively high sensitivity. That makes them good for lower powered amps, but high sensitivity woofers IME tend to not exactly plumb the bass depths and changing those woofers out for something like, say, Acoustic Elegance ob woofers (which are likely a bit more expensive) and you're at a sensitivity of around 90 or 91 dB. It may require a little more power than the Eminence, but you might experience a sizably different character of bass response in the room. One that may begin to show you just what a wide world of bass choices there exists out there to try out and to discover. 

By the time you've taken a crack or two at that, maybe then it may make more sense for you to resort to measuring to further your cause.

In the long run, I suspect ob bass will be better for you to get an overall satifying result than with boxed subs, but with a little more experience down that road, you might discover more reliably than now which you might really prefer, the clean, open ob sound that isn't as fully impactful, or the wallop of a good boxed sub that isn't really as transparent overall. 

Hope this helps.

Attack and snap In the bass relies on other frequencies above 200Hz. Are you overthinking this?

The baffles were bought with Altec 416B drivers and Saba Greencones, and the crossover point was set much higher (about 450Hz). This worked well until I upgraded the Sabas for Cube Audio FC8s. These were now capable of playing full range down to 200-250 Hz and this became the new crossover point. I did this as, in open baffle, the FC8s outperformed the Altecs in the range 200 to 450Hz. Having only to cover the frequencies below 200Hz was better suited to the Eminence drivers which were almost universally recommended for this use.

Out of interest I don’t play very loud 75db and the base driver cones barely move even though they give adequate volume,

Pedroeb forgive my ignorance, but what am I looking at in that graph. I don't use the region 200Hz + where it is pretty ragged and have accepted that below 100 Hz its output is poor, exacerbated by the OB. But this is true of most 15" drivers in OB.

Ivan_nosnibor   "That makes them good for lower powered amps, but high sensitivity woofers IME tend to not exactly plumb the bass depths"

Is there a reason why this may be, and are there any lower sensitivity 15" drivers that I could think about. Power is not an issue as I have a 1000Wpc Ice amp available.

@bumpy48, I'm taking it that your listening experience is related to playing full range music but without the higher frequency drivers connnected. If that is the case, then I'm not sure that the listening experience will be that useful since the majority of bass instruments have harmonics way above the 200hz. That's precisely why there is a disjunction between what you hear when playing the bass drivers alone and then playing full range. You could get a synthesiser and play some sinewaves in the chosen frequency range but that won't be particularly educational either, I think.

Yoyoyaya  Looks like you are right about this, but it was a surprise to me and I needed a reality check.


I tend to agree. It’s as if you’re trying to fix what may not be broken. Without hearing the range of frequencies the instrument produces, it will never sound right. A bassist plucking the lowest note on the instrument cannot be reproduced if frequencies above 200 are excluded. 

The frequency response chart is from a test infinite baffle.  It is not as good an indicator as the response for the speaker in cabinets so please look at the fr in the PDF.

Having said that, the example cabinets say if you try to use this in the home you are going to need a lot of EQ to get to neutral, and that brings us back to measurements. This is a speaker with a lot of tone for stage performance.

A few things.... In general, listening to 150 to 250 hz alone sounds like mud. You are listening to the highest bass regions or more arguably the lowest midrange frequencies. Thanks to @pedroeb for posting a link to the driver. This driver has a QTS of 1.26, that alone tells you that this woofer is ideal in a huge sealed box or free air situation, but also, this very high QTS also tells a story of how this driver can react. Also, you are correct about the graph.  That spike is huge, but crossed at 200hz at 24db per octave that driver is down near 100db by the time it reaches that spike. 

So a few suggestions. Make sure that you use an amplifier with great control over your woofer, it doesn’t have to be tons of power, but most likely should be. You are after an amplifier with good current capabilities.

Placement is critical, this woofer will respond to boundries in the 200hz range like few others. Distance to the floor and rear and side walls all matter.

I suggest that you download Room EQ Wizard software. It is free and works fairly well. I’ve seen it said a few times in this forum to measure speakers very close to the driver. in this case, measure from the seating position first, then move the mic closer to the speakers up and down and side to side and look where your boundries have peaks or dips in the frequencies that you are concerned about. Also look for a hole right above 200.  You do not need a crazy expensive mic, the idea hear isn’t to get accuracy to a tenth of a db, plus or minus 1db will give you a look at what you are dealing with. I suspect that you are dealing with your room. .

When I was a college student in the early 80's we created a tape of many different instruments playing the exact same note.  We used woodwinds, brass, strings, tubular bells, you name it, we had access to the entire orchestra's instrument room.

We then deliberately removed the attack and decay of each note played, leaving only the sustained note.

We then played the tape of notes to a group of listeners and asked them to identify the instrument playing the notes.  And no-one could do it.

We then wrote the instruments on the chalk board and told them these were the instruments they could match up to the notes and played the tape again and only a few were identified.

What this experiment tells us is that the way we perceive an instrument's sound has as much to do with the attack and decay as the note being played.  Thus when you only focus on the lower end of the frequency spectrum of an instrument you are in a similar way eliminating much of what you need to perceive what you are hearing; after all the attach and decay is mostly in the extreme frequencies.

Taken into consideration you might find it interesting to listen to the whole instruments frequencies, and then replace the lower end with different technologies renderings to get a better perception of the whole sound as it changes.

You may find that by nature some technologies render some instruments with lower frequency spectrums more to your liking than others, mostly depending on the instruments overtones and how the attack-decay-sustain sounds overall with the chosen technology.



Send them-in to Danny R! loL

sorry couldn’t resist.

audioaural site has some basic info that may help here.


This is one of the reasons why certain songs sound way better than others with respect to bass. The building blocks of having better bass, is to make sure you have the bass frequencies in their proper positions. 

Having clean bass frequencies is enough to get amazing bass through any audio system.

The bass frequencies are from 20Hz to 160Hz. The best frequencies to boost for bass in a song, are around 50Hz and 80Hz. These frequencies make sure that the bass sounds full and powerful. All bases should be subjected to a bell curve at the key of the song.

Bass in an audio track is between the 20 to 400Hz range of frequencies. The frequencies are shorter and longer when compared to the higher frequencies.

I probably missed it here, but, are you running a system with two fifteens per side? One crossed over to the other? I am confused and your question is interesting. By the way I play and have recorded bass.

+1 recherche

Awesome experiment... Demonstrates/Presents this problem from the Opposite direction.

Which comes first?

The Instrument or the Playback Equipment?


"Is there a reason why this may be, and are there any lower sensitivity 15" drivers that I could think about. Power is not an issue as I have a 1000Wpc Ice amp available."

There may well be reasons, but if so, they’re above my pay grade. I’m no driver designer or TS parameter expert. But, I think that it’s not so much that there might be exceptions, so much as there might be ’near-exceptions’ to some sort of iron law for it that I’ve never been able to work out. Part of that problem is that traditionally woofers are hardly ever designed for specific applications from the ground up, instead they’re usually ’crosspollinated’ and shoehorned into more or less filling a need. Many, many woofer designs out there are "dual" or "multi" purpose, convenient for the manufacturer maybe, but a compromise for the user no matter which way with them you go.

That’s really what I happen to like about Acoustic Elegance. John up there in Michigan never makes a woofer until he has gone back to the drawing board and has fully and independently designed and manufactured, all in-house, just one, single, definitive model (from any, one maker, that should be all you need) for each and every possible woofer category (infinite-baffle, bass-reflex, bandpass, sealed, etc, etc) need screw around with anything dual-purpose ever again. That allows you to start with the app alone and then buy someone’s deliberately best-conceived design for that app. From there, you basically just choose the woofer size, and how many of them, you need. What you get is something designed for your, particular app that was never compromised from the start.

But, don’t let anyone kid you, bass response in the room is really one of the very hardest things to get right in all of audio, even when going ’by the book’. And depending on how ambitious or not you want to be with it all will certainly dictate what you might want to try. But, IME, I find that the ’just right’ level of bass performance is a very difficult thing to try ’sneak up on’ and hit on without any overspending at all. For my money, it’s much more successful to get a better woofer and ask it to do something Less than it was designed to do than to ask of the ’just-right’ woofer to do something More than it was designed to do.

In fact, if it were me, I’d be looking at using only one, good driver type (per side) below your 200 Hz xover point. That way you can eliminate the xover to the sub altogether. That’s very important to the overall character of the bass response in the room. The fewer xover points the better, with 3-way systems sounding nearly Always the best, overall. Crossover effects are actually quite audible and even the very best and most expensive of them will degrade the sound to some extent, and if not so much in frequency, then in terms of coherency and dynamics. I think those sorts of advantages can often end up being the first casualties when we get too caught up in chasing the lines on a graph.

Of course, all this is just my 2 cents and it’s mostly so much audio philosophy, but it’s maybe the kind of thing that if my present-day self could go back in time and give audio advice to my 30-year younger self, it would likely include something like that.

My system is multiamped and crossed over with boxcar digital filters. By happy coincidence it crosses from bass to mid at 190hz, and I can shut off the mid/high power amps and just listen to what’s below 190hz, which I do on occasion to be sure channelization is intact on the computer’s soundcard driver before I subject the mid/hi horns to possible damage. I don’t have bass horns, but I do have a pair of Altec 421a 15"ers that are as clean and fast as any woofer, and it sounds like mud. Absolutely all definition and location (aka harmonics) from any bass instrument, even a pipe organ, comes out of the horns. With everything on the bass sounds fabulously crisp.

The room has a ton to do with bass under 200hz. Is your room small or square? 

When I hear about slow, sloppy, undefined bass, it is usually a room with a long decay time and ringing. 

It’s the fact that you have these bass drivers in open baffles. That turns their radiation pattern into dipole (radiating to the front and back more or less equally), and that tends to rob the bass of impact unless compensated for in various ways.

I remember reading reviews of Legacy Audio’s then TOTL speakers which were open baffles with 2 x 12" drivers at the bottom of each speaker. The bass was typically described as nuanced and delicate, but not up to dance party standards. A case where the speakers looked like they would shake the foundation but could not, because of the open baffle & dipole radiation pattern...