Building a two way bookshelf

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#61
I am reading materials to gain knowledge asap. This world is new for me. But, since my degree is related to electronic, I understand the terminology. I found an article with something that called my attention :

"A basic, ages-old but still true, rule of thumb states that a designer is usually safe when he crosses a driver over at double its resonant frequency. If a tweeter has an Fs of 1500 Hz, use a 3000 Hz crossover, minimum. If a midrange is 300 Hz, use 600 Hz.

Another good rule of thumb says, “18 dB down at resonance.” If a tweeter’s resonance is 1500 Hz, the voltage curve of the crossover should show the tweeter section being down 18 dB from “0 dB.” That kind of conservatism all but assures no tweeter burn-out.

This was the “rule” at a major speaker company I used to work at, and the engineers all hated it, because it was so conservative and resulted in very high tweeter crossover points. But we almost never lost a tweeter and our warranty costs were vanishingly low. ‘Real world’ vs. ‘theory.’ "

Thanks to all you for the contributions.!
 
#62
dvjorge said:
I am reading materials to gain knowledge asap. This world is new for me. But, since my degree is related to electronic, I understand the terminology. I found an article with something that called my attention :

"A basic, ages-old but still true, rule of thumb states that a designer is usually safe when he crosses a driver over at double its resonant frequency. If a tweeter has an Fs of 1500 Hz, use a 3000 Hz crossover, minimum. If a midrange is 300 Hz, use 600 Hz.

Another good rule of thumb says, “18 dB down at resonance.” If a tweeter’s resonance is 1500 Hz, the voltage curve of the crossover should show the tweeter section being down 18 dB from “0 dB.” That kind of conservatism all but assures no tweeter burn-out.

This was the “rule” at a major speaker company I used to work at, and the engineers all hated it, because it was so conservative and resulted in very high tweeter crossover points. But we almost never lost a tweeter and our warranty costs were vanishingly low. ‘Real world’ vs. ‘theory.’ "

Thanks to all you for the contributions.!
Click to expand...

It depends on the nature of the products. If you build Ferrari's, warranty costs may not be an issue, whereas Toyota it definitely is an issue.
 
#63
marco_gea said:
True. OTOH, ~2-3kHz is pretty much smack-dab in the middle of our auditory system's highest sensitivity range, so any discontinuities between drivers and/or aberrations induced by the crossover are likely to be more audible...
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See, I think we confuse ‘sensitivity’ with ‘perceptivity.’ I don’t think we’re any better at perceiving crossovers at that frequency just because our ears are more sensitive in that region. Just add a little BBC dip and you’re good to go. 😎
 
#65
I think a lot of people might be under misapprehensions about the actual pitch of various frequencies. I used to wonder why the full range folks thought that crossing full range drivers around 3-400hz (the typical FAST design) would be superior to the typical 2-way XO point of ~2khz. 3-400 is smack-dab in the middle of most instrument and voice ranges, whereas 2khz is already getting into overtone territory:
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What you are missing here is that an instruments will be recognized by the overtones that produces. No instrument will play a single sine wave. String instruments have really a lot of high harmonics content, and in a single note the sum of all the harmonics but the first is greater than the fundamental alone (1st harmonic). So thinking that the 300-400Hz region is more important because it contains the fundamental of many instruments is actually false because the higher harmonics are more important as they will give you the tone of a note. Without overtones you wouldn't distinguish between a violin and a trumpet nor a human voice.

Have a look here for the violin spectrum (B note, roughly 497 Hz):
An externally hosted image should be here but it was not working when we last tested it.


Ralf
 
#68
Thank you.! What I am thinking is to shorter the high and width and to add what I subtract to the deep but keep the same internal volume . Yes, I know it is important stuffing and it is a point I need to learn and clarify to do it right. Step by step.
 
#71
1.3 cubit feet sealed enclosure for a 8" woofer

Hi,

First of all, I want to apologize for my questions. I have been researching how to build a set of bookshelf using good drivers. The things are a little bit more complicated that what I thought.

I have a friend that can give me a couple of Yamaha bookshelf in very good conditions. They are sealed, something that I like. Of course, I am going to remove the drivers to use better drivers and crossovers.

The dimensions are H 16.5 x W 10.5 x D 13.2. (external dimensions inches)

I calculated the internal volume subtracting the MDF thickness and got a volume of 1.3 cu/ft or 31.20 L

Most of the 8" drivers I have seen recommend an 0.5 or 0.75 cu/ft for a sealed enclosure. My question is if I can use this boxes to build my project. The size of the Yamaha enclosures are ok for me and they are mint. By the way, the Yamaha are built using a 8" woofer.

Thanks for any help.!
 
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#72
Fantastic to get LR4 with so little components! I still need to construct my own enclosures first and measure the drivers there for crossover design. Will also try stepped baffle for physical time alignment.

I'm exactly aiming for a little more impact on the vocal range. My current system is 2x12" with 3" full range. It is otherwise fine, but voices lack something. I asked my singer friend if she can present a couple songs on my listening room which really highlighted the faults of my current setup.

Incidentally, I also possess the 22W/8534G00. Might try it as well to the enclosures when they are done.
 
#73
Mayuri said:
Fantastic to get LR4 with so little components! I still need to construct my own enclosures first and measure the drivers there for crossover design. Will also try stepped baffle for physical time alignment.

I'm exactly aiming for a little more impact on the vocal range. My current system is 2x12" with 3" full range. It is otherwise fine, but voices lack something. I asked my singer friend if she can present a couple songs on my listening room which really highlighted the faults of my current setup.

Incidentally, I also possess the 22W/8534G00. Might try it as well to the enclosures when they are done.
Click to expand...

Please, share with me your results if you don't mind. I may follow you.!
 
#75
Here's my 830869. The 3-way is in a 20L box. The 2-way is with a JBL 2342 horn with a JBL 2425 compression driver. Both are BR.
 

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#80
Does someone can give any help with it ?


First of all, I want to apologize for my questions. I have been researching how to build a set of bookshelf using good drivers. The things are a little bit more complicated that what I thought.

I have a friend that can give me a couple of Yamaha bookshelf in very good condition. They are sealed, something that I like. Of course, I am going to remove the drivers to use better drivers and crossovers.

The dimensions are H 16.5 x W 10.5 x D 13.2. (external dimensions inches)

I calculated the internal volume subtracting the MDF thickness and got a volume of 1.3 cu/ft or 31.20 L

Most of the 8" drivers I have seen recommend an 0.5 or 0.75 cu/ft for a sealed enclosure. My question is if I can use this boxes to build my project. The size of the Yamaha enclosures are ok for me and they are mint. By the way, the Yamaha are built using a 8" woofer.

Thanks for any help.!
 
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