DIY Two-way Loudspeaker

[Audio_Noob]

Hello everyone,

Im currently just finishing up renovations on my basement room, 23'x12'. It has been converted almost into a 'dancehall', including DJ lights, smoke machine, mixing board, computer 'station', etc...

When starting the renovations I purchased a small sized, powered floor monitor. It has a built-in EQ, Bullet style horn + tweeter, and 12" 'woofer'. Im still a little confused on it, (Peavey 112PM Floor Monitor). The site says it is a 75W system at 4 Ohms. The unit itself has a 300W notice on it... I think this is because the amp might be at 8Ohms? Or, I might be lost, I guess this part is beside the point.

Anyways, I am very eager to add more sound to the room before I start bringing in guests... and have been looking at the option of building my own Loudspeaker.

One of the better materials I've heard of using for building speakers is baltic birch(I know Mackie uses these). I have 40 acres with many birch trees as material, although im unsure of the type of birch(white wood though, and not oily/sap-filled). I know the type of material used for the box effects the sound or 'knock' of it with the low frequencies. Having a fully equiped shop at my disposal, im inclined to build my own enclosure.

I still have a little difficulty understanding amp selection... for example, an amp with a description of 2 x 495 watts at 8 ohms , would either mean it would drive two two-way speakers at (half) that 495w each, or it might drive both a tweeter and woofer in one box? Im not sure if the 2 indicates two channel, which would mean it could run stereo, or what?

The amp selection, I have understood, should have an output power higher than, or double that of the continuous power rating of the loudspeaker. Is this truth? Also, how do I know an amp will not peak higher than the speaker's rated peak? + Is the damping factor commonly listed on amps?

As for the drivers, etc... I would like to use a single, yet powerful tweeter, (with a large/broad shaped horn), and either likely two 12" woofers, or 2-5 10" woofers. Mackie suggests such designs provide 'tighter base response, greater power handling, and far more impact". Is this truth? Also, I am inclined to make a taller speaker box, standing about 4' tall, thus dual 12's or 15's would be possible/suitable.

In my situation I will only be using one speaker, operating it as a 'mono' output on my mixing board. I assume this will affect my amp selection?

Now, component wise, im not sure if there is a best place to look. I know I can get some from peavey, or a few other websites online, but im wondering if there is a better source? For electronics connections within the speaker... I need the drivers themselves, as well as a crossover? Or two? Im a little confused as to how they work/what they do. Would my input sound connect to the crossover, then to the amp, then the speakers? Or, Into the amp, crossover, then speakers?

And I guess I forgot one last thing. Venting the box for the woofers. I understand the suggested vent depth is 1/2 the depth of the box? Should the vent be carpeted?(A friend has an amazing subwoofer with a monster, 3 side perimiter carpeted vent in his car). And I have heard a box(for a woofer anyways), should be 0.8 x 1.0 x 1.2 times the size of the woofer? (those are 'ratios'). I would guess the first number to be depth, front to back, and other two as width and height, in that order? Should this LF section be physically 'seperated/divided' from the top HF section?

Sorry, my post is overwhelming, but, any help/tips/directions are much appreciated!

Thank-you for reading/replying!

Chris

 

[nav]

When starting the renovations I purchased a small sized, powered floor monitor. It has a built-in EQ, Bullet style horn + tweeter, and 12" 'woofer'. Im still a little confused on it, (Peavey 112PM Floor Monitor). The site says it is a 75W system at 4 Ohms. The unit itself has a 300W notice on it... I think this is because the amp might be at 8Ohms? Or, I might be lost, I guess this part is beside the point.

The "300W" by the IEC power jack is the potential amount of power consumed; that is, pulled out of the wall.

One of the better materials I've heard of using for building speakers is baltic birch(I know Mackie uses these). I have 40 acres with many birch trees as material, although im unsure of the type of birch(white wood though, and not oily/sap-filled). I know the type of material used for the box effects the sound or 'knock' of it with the low frequencies. Having a fully equiped shop at my disposal, im inclined to build my own enclosure.

Hardwood can be suitable, but plywood (Birch or otherwise) is preferable in many ways. MDF is heavy and more predictable and generally easy to work with (and, for most people, cheaper).

I still have a little difficulty understanding amp selection... for example, an amp with a description of 2 x 495 watts at 8 ohms , would either mean it would drive two two-way speakers at (half) that 495w each, or it might drive both a tweeter and woofer in one box? Im not sure if the 2 indicates two channel, which would mean it could run stereo, or what?

The "2x" means it has two powered outputs, so it can be used for stereo. How the power is divided and such depends on the source of the power rating.

The amp selection, I have understood, should have an output power higher than, or double that of the continuous power rating of the loudspeaker. Is this truth? Also, how do I know an amp will not peak higher than the speaker's rated peak? + Is the damping factor commonly listed on amps?

That's too simplistic of a generalization. Clipping and other distortion are the primary concerns from over-driving an amplifier. Knowing how much you can expect from an amplifier depends on more than the advertised power rating. Total desired SPL output should be where you begin and will depend on the size of the room (distance from the speaker or speakers) and the sensitivity of the speaker as well as the power output of the amplifier.

As for the drivers, etc... I would like to use a single, yet powerful tweeter, (with a large/broad shaped horn), and either likely two 12" woofers, or 2-5 10" woofers. Mackie suggests such designs provide 'tighter base response, greater power handling, and far more impact". Is this truth? Also, I am inclined to make a taller speaker box, standing about 4' tall, thus dual 12's or 15's would be possible/suitable.

Consider driver displacement and driver-enclosure resonance frequency. The system resonance frequency will determine the natural (unequalized) frequency response of the speaker. Multiple smaller drivers can equal the displacement of larger drivers, but may or may not achieve the same frequency response. Depending on the circumstances, extra drivers can lead to lower total distortion (less power and excursion from each driver) and higher efficiency, but there are more things to consider before making such assumptions. The "tighter base (sic) response" line depends on a lot more than the number or size of the drivers.

In my situation I will only be using one speaker, operating it as a 'mono' output on my mixing board. I assume this will affect my amp selection?

One channel of an amplifier can power multiple speakers with the same input signal. Whether this is desirable or effective depends on the situation.

For electronics connections within the speaker... I need the drivers themselves, as well as a crossover? Or two? Im a little confused as to how they work/what they do. Would my input sound connect to the crossover, then to the amp, then the speakers? Or, Into the amp, crossover, then speakers?

For a passive crossover the signal runs into the amplifier, then the crossover (normally contained within the speaker), and then to each of the drivers. For most active crossovers, the signal runs into the crossover, to multiple channels of amplifiers, and then to multiple inputs on the speaker.

And I guess I forgot one last thing. Venting the box for the woofers. I understand the suggested vent depth is 1/2 the depth of the box? Should the vent be carpeted?(A friend has an amazing subwoofer with a monster, 3 side perimiter carpeted vent in his car). And I have heard a box(for a woofer anyways), should be 0.8 x 1.0 x 1.2 times the size of the woofer? (those are 'ratios').

Those rules are far too simplistic to achieve predictably good results. Box vents and enclosure size relate to tuning frequencies for the system. Vented enclosures are very size-sensitive and must be properly designed to function optimally.

Should this LF section be physically 'seperated/divided' from the top HF section?

It's generally desirable to isolate different drivers from one another.

Designing and building a speaker is a lot more complicated than you may have been lead to believe. As a hobby, I've been researching, writing software, and otherwise experimenting for at least a year in matters of acoustics, enclosure and crossover design, and other topics and I fully consider myself a newbie to the field.

You might want to start reading some introductory material such as The Subwoofer DIY page. It tends to "get right the point" without in-depth discussion of the sciences involved, but it'll hopefully show you some of what you'd need to select a driver and design an appropriate enclosure for it. There is free software available such as WinISD that can do some simple modeling of a driver and enclosure (my aforementioned software is not yet publicly available, it's over a year away from usefulness at my current rate of progress).

I hope that helps .

 

[Audio_Noob]

Thanks for the info... After a few weeks I ended up deciding just to buy a speaker.

Initially I was looking at a Peavey SP 5.5 (Powered). It is much louder and sounds a tad better than my current peavey, but, at higher volumes the sound was becomming distorded (clipping, etc..). I had heard mackies were all the rage alot but someone at the store I frequent had talked them down and said the peavey I was looking at was pretty good, or an EV. A customer said a little something about mackies, so we ended up plugging a model similar to the one I was looking at(the series down from it), and boy was it great.

It got SO LOUD, not full vol. though, and the bass was immaculate, top end was super clear, and the midrange wasnt fuzzy at all. I ended up walking out with a deposit on an SA1521z. Powered two way -

SA1521z Link

I have yet to hear one or see one in person but judging by the mackie reviews, and how pleased I was with the model down from it, and considering the SA on paper looks better too, Im pretty pleased with the purchase.

Just thought I would give a + for Mackie.

And thanks for the help Nav.

Chris