Speaker size characteristics

[Alex]

Crockettnj - That's also something that I was wondering!

Read the works of Neville Theile and Richard Small and you'll begin to find out. The scope of the subject is quite literally enough to require the equivalent of a Master's degree in audio engineering to fully understand.

That's what this thread is for! I think that choosing a cab should be more than playing it and picking what sounds best. Hopefully someone's an expert and will inform us all. We could all benefit from this knowledge.

 

[etnops]

well, this is a loaded question for sure. you're basically asking for a correlation between the physical breakdown of a speaker to perceived subjective interpretation. the fundamental flaw here, is the limitation of language. what "warm" sounds to me, might not what "warm" sounds to you...and so on and so forth. it's all about the human filter, and how we're all different filters.

to understand speakers themselves and how they work in the physical realm requires a fair bit of understanding, study, and spacial reasoning skills. to understand how we as humans percieve sound is a whole other ball of wax. i don't mean to be rude, but having an expert "sum it up" on an internet forum is a bit far fetched.

i suggest starting at the very beginning. seriously. find "acoustics" by leo baranek, and study it well. it's considered THE bible in the speaker world.
a good idea would be to either become a member, or pay $5 per journal at www.aes.org. there is an absolute PLETHORA of information about speakers there, that cover this very subject, to acoustic theory and everything in-between. i can't tell you how many weekends i wasted at college reading old aes journals, drinking coffee and smoking cigarettes until all hours of the night.

again, i don't mean to be rude, but a few of us here could probably type for 3 days on this very topic, but i think it would all be in vain. if the reader doesn't understand the very core fundamentals of the two issues you're trying to dissolve, then a total or spacial understanding cannot be achieved. again, i'm not trying to be rude, i'm trying to be realistic.

what i suggest, is get out there and start DIY building hands-on yourself! there is NO better way to learn about this very subject, then to buy the raw materials, and throw together a cab and start observing and playing! seeing every component from conception to birth is a learning process that no internet forum, book, or class could ever teach you. i've been doing this for the better portion of my life, and there are volumes of text in my brain that i wrote, and that only i can understand...because my perceptions went thru me.

i know this probably doesn't help, but what i questions i can answer easily i will. this one however, deals with eternal questions of axiology (what is good), and only the asker of the question can answer it.


-SDP

 

[ESP-LTD]

what "warm" sounds to me, might not what "warm" sounds to you...

Ok. So what you're saying is that big speakers have lots of rumble but not much punch and grit, while small drivers can be more ringy and have a good bite but not so much thump? I mean, driven with tube watts of course ...


It almost sounds like English, except for the fact that it really doesn't communicate anything.

 

[fdeck]

to understand speakers themselves and how they work in the physical realm requires a fair bit of understanding, study, and spacial reasoning skills. to understand how we as humans percieve sound is a whole other ball of wax. i don't mean to be rude, but having an expert "sum it up" on an internet forum is a bit far fetched.

Probably true. But we could have more modest goals, which is to have an expert (or a physicist posing as an expert) offer some general advice -- tell us where we can use our brains, and where we must trust our ears instead. Experts and serious amateurs can also join in the attack against hyperbolic marketing claims and misconceptions.

For instance, I think that I now understand why the mythical tradeoff between cone mass and speed is... mythical. Assuming that I am correct, clearing away this misconception forces us to look elsewhere for the answer as to why so many people think 10" systems sound better than 15". We may never arrive at a total understanding, but at least it helps to be guided in the right direction.

Maybe I am wrong about Thiele / Small, but it seems to me that they spent a lot of time with analogies to electrical filters that have been rendered unnecessary by computerized analysis. Near as I can tell, the on-axis bass response is governed by only four parameters: Overall gain, box frequency, total Q, and port frequency. All of the T/S parameters merely serve to compute the big four, for a given box configuration.

Can anybody tell me the formula for off-axis response from a piston driver? Is it a Bessel function? Sorry for being intellectually lazy.

 

[fdeck]

Purely for recreational purposes, it is fun to check out this web page:

[Invalid or Expired Link Removed]

This page does not cover ported systems. I sat down and derived the equations for port behavior, because I enjoy math. If I ever get ambitious, I will post them on my web page, or -- perish the thought -- crack open a book and see if my equations are actually correct!

 

[billfitzmaurice]

Can anybody tell me the formula for off-axis response from a piston driver? Is it a Bessel function? Sorry for being intellectually lazy.

In a simplistic way you could just assume that a driver is directional when its radiating plane is one wavelength across, and you'd be wrong. That only holds true if the radiating plane (cone) is of a constant composition, which by and large they aren't. With pro-sound drivers in particular the dust cover often serves as a radiating plane semi-independant from the rest of the cone, so you can't figure axial response based on the size of the cone alone. There are so many variables present that the only way to be sure is to measure it.

Maybe I am wrong about Thiele / Small, but it seems to me that they spent a lot of time with analogies to electrical filters that have been rendered unnecessary by computerized analysis

The only thing changed by the use of computers is that the software does the calculating for you; the formulas remain the same.

 

[bgavin]

Can anybody tell me the formula for off-axis response from a piston driver?

(Pressure Off-Axis / Pressure On-Axis) =

1 - ((kr * sin off-axis-angle) / 8)

k = (2*Pi*frequency / c)
r = piston radius
c = velocity of sound in air

 

[billfitzmaurice]

(Pressure Off-Axis / Pressure On-Axis) =
1 - ((kr * sin off-axis-angle) / 8)
k = (2*Pi*frequency / c)
r = piston radius
c = velocity of sound in air

Quite right. But as I alluded to in my previous post many drivers are actually two concentric pistons, the main cone and the dust cover. For example, go to the Eminence site and look at the response charts for the Beta 10 and the Legend BP102. The drivers have virtually identical cones, but very different HF responses. Why? The Beta 10 has a solid dust cover, which acts as a smaller secondary piston. The BP102 has a porous dust cover, which does not act as a secondary piston. The resulting HF response of the two tens is thus very different, both on and off axis. To figure the off-axis response of the Beta you have to consider both pistons, and also the additive and subtractive phase interactions where both pistons are reproducing the same frequencies. And then there's cone break up. Yes, there are some simple equations to predict driver responses, the problem lies in that there are over a dozen simple equations operating simultaneously. The sum total of the permutations of all those equations is long enough to fill an entire page.

 

[Ben Clarke]

My two 1x10"s sound radically different. Might have something to do with the boxes, right Bill?

 

[bgavin]

The JBL "Chrome Dome" is good for a bunch for the same reason. I measured my E155 at -3dB from peak at 1500 Hz.

 

[billfitzmaurice]

My two 1x10"s sound radically different. Might have something to do with the boxes, right Bill?

I have the advantage of knowing what boxes those are, and yes, quite true, but yours are horn loaded, and where horns are concerned 90% of the performance is dictated by the cabinet, only 10% by the driver in it. With a large enough horn I could blow away an 8x10, badly, using only one four inch driver. I wouldn't want to have to haul it to gigs, though.

 

[fdeck]

The sum total of the permutations of all those equations is long enough to fill an entire page.

Just a page? You make it sound too easy

I appreciate all of the good advice. My attitude is that I like to know what the basic theory is, even with the understanding that there are permutations.

 

[ImSquare17]

There is an absolute PLETHORA of information about speakers there, that cover this very subject, to acoustic theory and everything in-between.

Plethora looks funny in all caps.

 

[Ari]

This is an interesting thread, in fact I was looking for a topic like this since lately I have been experimenting with my different speakers to hear and understand the differences between them.

Today I've done some playing tests with my DB359 and then with my Iamp 350, first with my Berg HT115 and then the HT210, everything flat on the amps.

It's not always easy to describe the sounds in english but here's what I'm hearing. When I want a jaco type fingerstyle sound with the bridge pickup I prefer what I'm hearing through the HT115. To me there is more "thump", more midrange. The HT210 sounds more modern, the bass kicks a bit more, it is more precise in the lows but the mids have less warmth and the highs are clearer.

For a slap sound with both pickups on, the 210 gives a more modern sound where the 115 has more of a "vintage" vibe... To me the 210 sounds more "closed"... but I have been thinking about it and maybe it's because it's not broken-in yet, I would say it only has a few hours of playing whereas I already gigged several times with the 115 and I think it impacts the sound of the speaker.

My HT112 is at another location so I couldn't test it with the other speakers but from what I remember I would say the 112 is the more midrangey of the bunch. When I play through it I have a tendency to activate the "contour" switch on the amp since I don't like to have too much mids.

Unfortunately I have stopped gigging so this experience is quite limited - IMO the only way to really judge a speaker is in a gig situation.

 

[DistantTremor]

Size in and of itself is only about 1/15th of what determines a drivers sound. You could play the same cabinet loaded with a dozen different varieties of the same size driver and have a dozen different responses. The short answer to your question is that there is no short answer.

Alright I'm about to bump this thread because it looks like the question that was posed in the first place was almost answered here.

After browsing the amp forums for the last few days I've realized and accepted that no speaker size is optimal in all situations, nor do speaker sizes make up enough of the difference to determine one cab purchase over the over.

HAVING SAID THAT, let's say we have two speaker cabinets.

Both of them are identical in all ways, except for the speaker size.

I don't care if there is no audible difference caused by the difference in size. But physically speaking, there HAS to be a difference caused by speaker size in SOME WAY, because the speakers will move the air in a way that is somehow different.

So, what is the difference that speaker size causes?

 

[boristhespider9]

This thread is insane. Buy a 1x15 and 4x10 stack and be done with it.

 

[silky smoove]

Both of them are identical in all ways, except for the speaker size.

I'll eat my shoe if you can show me two drivers where the ONLY difference is the nominal cone diameter. It is moot because it doesn't exist in the rule world.

EDIT: Thought about this for another second. Other than being moot, you could characterize that the speaker with the larger cone diameter would have more narrow horizontal dispersion. It's still moot though.

This thread is insane. Buy a 1x15 and 4x10 stack and be done with it.

I can't tell if this is sarcasm or not.

 

[Korladis]

Alright I'm about to bump this thread because it looks like the question that was posed in the first place was almost answered here.

After browsing the amp forums for the last few days I've realized and accepted that no speaker size is optimal in all situations, nor do speaker sizes make up enough of the difference to determine one cab purchase over the over.

HAVING SAID THAT, let's say we have two speaker cabinets.

Both of them are identical in all ways, except for the speaker size.

I don't care if there is no audible difference caused by the difference in size. But physically speaking, there HAS to be a difference caused by speaker size in SOME WAY, because the speakers will move the air in a way that is somehow different.

So, what is the difference that speaker size causes?

If they are the same in frequency response, excursion, all that stuff... then the larger driver will be louder, due to moving more air.

It will still start beaming the mids and highs at a lower frequency.

In this hypothetical example, I think those would be the most significant differences. In tone, if the frequency response is the same, then they would sound basically identical on-axis.

 

[billfitzmaurice]

So, what is the difference that speaker size causes?

Dispersion.

I'll eat my shoe if you can show me two drivers where the ONLY difference is the nominal cone diameter. It is moot because it doesn't exist in the rule world.

It certainly does exist.
I suggest you go with the loafers.

 

[silky smoove]

You're saying that there are two drivers with identical parameters in every way, except for the nominal cone diameter? I find this hard to believe, and something I think I've seen you comment about here on TB... While I agree that If anyone knows the answer to that it would be you, I can't say that I'm prepared to bite into my Adidas just yet... Although with a little hot sauce they might be delicious.