Bookshelf VS Tower - mid-range SPL

Jon AA

Jon AA

Junior Audioholic
Wouldnt crossings over a 15in woofer at such high frequency cause an unnatural sounding spike in SPL above say, 120Hz? Given the assumption you plan on driving this woofer down to say ~20Hz. My thought process is the power required to create the desired SPL and to accurately drive that woofer down in the 20-35Hz range would be excessive over 200Hz.....
Yup, that's definitely getting into the nitty gritty of speaker design. ;) While that certainly could happen, the job of the speaker designer is to make sure it doesn't. Box size/tuning, driver parameters and crossover design all need to work together properly. Some pull it off better than others.... In this case I think the guys who designed this speaker did a pretty good job based upon the measurements I've seen. They use a custom pro audio driver that's very sensitive so they don't need much power and can be tuned flat pretty easily. Even these though, won't hit 20 Hz, so I'll still use subs with them. But they'll certainly allow the subs to do what they do best, the midrange to do what it does best without having a hole in capability in between.
 
lovinthehd

lovinthehd

Audioholic Slumlord
Yup, that's definitely getting into the nitty gritty of speaker design. ;) While that certainly could happen, the job of the speaker designer is to make sure it doesn't. Box size/tuning, driver parameters and crossover design all need to work together properly. Some pull it off better than others.... In this case I think the guys who designed this speaker did a pretty good job based upon the measurements I've seen. They use a custom pro audio driver that's very sensitive so they don't need much power and can be tuned flat pretty easily. Even these though, won't hit 20 Hz, so I'll still use subs with them. But they'll certainly allow the subs to do what they do best, the midrange to do what it does best without having a hole in capability in between.
What speaker is it?
 
Jon AA

Jon AA

Junior Audioholic
The DIY Titan 615LX. There's a lot of ways to skin a cat though, I was just using it as one example.
 
2

2channel lover

Audioholic Field Marshall
I'm sure this topic has been covered ad nauseam. Although, I can't find the exact answer to my question.

I'm looking to upgrade my "home theater in a box" and take the buy once cry once route. I'm looking for a 60% stereo music, 40% streaming 5.1 system. I'm more concerned with clean detailed forward mids and present but not harsh highs. Lows are definitely nice but I'll have that covered with the SVS pb3000 that's currently on the way. My room is, well... My whole house. It's open floor plan design, with two story open cathedral ceilings. As of now it will be powered off a simple Yamaha RX-V485. Will upgrade in the slightly distant future with an added power amp. Due to current power constraints, high sensitivity is preferred.

There... Got that out of the way. I was actually talking to a SVS rep and he pointed out that if budget is a concern and that I have the PB3000 coming then I should just get bookshelves of a higher quality vs a lower quality tower. He showed how bookshelves of the same "class" tend to have the exact same mid-range driver and the additional speakers are used for lows. I'm thinking fine, I like this idea. Now i'm sure it's just psychological but the physical size of the towers just says to me cleaner, louder... Mids included.

Does anyone have any experience on this? Should I expect the same SPL from a bookshelf as I would a tower in regards to mids and highs? If I EQ out the lows would I "gain an additional mid-range driver" with the towers?? (Seem impractical but worth an ask) If not would the low range woofers just not play? But a deep powefull male voice I would assume is within their crossover. Aswell a cello or bass guitar. I wouldn't want to loose the potential depth of these bands with a bookshelf, but I'm honestly not sure. I've just have not had the option to sit back and listen to them side by side at any reasonable volume. Especially not in a room of my size.
A little late to the party...some good advice thus far.

My 2 cents...

The quality of the drivers and crossover(s) tying the drivers together matters a great deal in speaker design so it's very possible, even likely a book shelf speaker with better drivers and crossovers will sound better than a floorstander speaker with lessor internal goods...but from my experience (demo with B&W 805d3 and 804d3 same room, electronics, content... 2.0 and 2.1) given comparable drivers/crossover the larger speaker typically will have better mid bass performance, wider soundstage...in a larger room, you'll notice the difference more than you would in a small space.

As mentioned, how close you sit makes a big difference as well....that said, if the funds allow go, with the towers in a larger room.
 
S

shkumar4963

Audioholic
You have asked a really pertinent and important question, seldom asked and even less understood by even professional designers.

The place to start is understanding this chart.



This shows the frequency range of common musical instruments and speech.

It also shows the the fundamentals in black and the harmonics in yellow.

Now there is more power generated by the fundamental than the overtones. Most instruments radiate even harmonics. That is to say if the fundamental is 400 Hz the second harmonic will be 800 Hz. Generally the power output goes down as the order of harmonics increases.

Now if you look you will see a heavy clustering of fundamentals from 60 Hz to 600 Hz, but going out to the 2.5 to 3 Khz range, after that range we are largely dealing with harmonic content. The big exception is pipe organs that have powerful fundamentals throughout pretty much the whole audio range. This makes them ideal for burning out tweeters.

The big point is that most power is required in that 60/80 Hz range to the 600 to 1000 Hz range, but significant power also required to the 2.5 to 3 KHz range.

But it is worse for speakers then it looks. Most speakers have forward facing speakers. Now for every speaker like that there is a point where it transitions from being a forward (half space) monopole radiator to a omni directional (full space) omnipole radiator. This occurs at a frequency depending on the front baffle width. The narrower the front of the speaker the higher this transition frequency. This is known as the baffle step frequency as at that transition the forward radiation goes down 6 db. For most speakers this occurs between 400 and 600 Hz. So unless the range below this frequency is boosted the speaker sounds thin. So this requires more then doubling the power output below this transition. That frequency unfortunately corresponds to the area where fundamental frequencies of instruments are concentrated.

So you are correct in your concern about lack of power bandwidth in this frequency range. I personally believe that most speakers are deficient in the required power band response in this region, especially since small bass mids have become the rule.

There are very few small bass mids that do have sufficient power response in this band, but there are some.

In practice it means that more than one driver to cover this band is actually required.

If you really understand what I have just explained you will see why the notion that bookshelf speakers and a sub have you covered is nonsense.

One last issue is that properly compensating for the baffle step results in an impedance drop below the baffle step frequency. So to drive a properly designed speaker with correct baffle step compensation really requires amplification that is comfortable with 4 ohm loads. This is a downside of more channels being added to receivers, as there seems to be a universal backing away of late from specifying performance at 4 ohm.
How about 3 way book shelf speaker like Kef R3?

Sent from my SAMSUNG-SM-G930A using Tapatalk
 
JerryLove

JerryLove

Audioholic Samurai
Does anyone have any experience on this? Should I expect the same SPL from a bookshelf as I would a tower in regards to mids and highs? If I EQ out the lows would I "gain an additional mid-range driver" with the towers?? (Seem impractical but worth an ask) If not would the low range woofers just not play? But a deep powefull male voice I would assume is within their crossover. Aswell a cello or bass guitar. I wouldn't want to loose the potential depth of these bands with a bookshelf, but I'm honestly not sure. I've just have not had the option to sit back and listen to them side by side at any reasonable volume. Especially not in a room of my size.
I think you are asking the wrong questions.

Efficiency, power handling, and FR curve will answer your question.

It's certainly not a "bookshelf vs tower" question.
It's not really a "2-way vs 3-way" question either, though that's closer to what you are *really* asking.

All else being equal (and all else is never equal) bigger drivers [in total surface area in the case of arrays] are capable of higher SPL (as they move more air for a given excursion).

So if you are looking at speaker A and speaker B,
and speaker A's largest driver is bigger than the largest driver on speaker B
and the crossover for speaker A's largest driver is significantly higher than the crossover for your sub.

Then there's a decent likelihood that speaker A can, maybe, run louder.

But realistially: you need to compare specific speakers. I run my home theater on Klipsch 650-THX's, and those are "bookshelves".
 

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