Building my own sub

[bluejay]

I intend to build my own subwoofer in the very near future. Most of my questions are on amps and hookups. I'll run some of my current ideas past you guys to be sure I'm not too far off base.

I've read up a bit on a few subs at Parts Express, Madison, Acoustic-Visions, and Creative Sound Solutions. Being on a bit of a tight budget I read up on the best stuff but then try to figure out if I can get away with something a bit less expensive.

So far my favorite choice for driver is a Subduction SD12. They are available at CSS for $155. It will be cheaper for me to buy from CSS because I'm living in Canada. I also like the design of the 4 cu.ft. ported cabinet they provide. I could eventually do a pair of them, but not sure when.

I can get the Bash 300 plate amp from the same place for $149.00. It looks good enough, but I have heard better recommendations about Keiga's, just not sure if I can get one for the same dollar.

Now comes the brain teaser, for me at least. I only have a 100 watt per channel Yamaha stereo amp. I have all my other music components as well as the TV plugged into it. My stereo satellite speakers are excellent to my ear and I don't want to change them. I am lusting over a Behringer 2500 or another pro style amp that would have sub outputs. With something like that I could build two unpowered subs and use them like that.

Can I parallel my existing speaker outputs and go direct to a powered sub? Would I just change my impedence switch to 4 ohms? Alternatively there is a line level output on my amp that is for going into an effects box or equalizer. For my amp to continue working I need to return that signal, (it is bridged now because I have never used it).

Well that is the beginnings of my questions. I haven't pulled the ripcord yet so I can change lots of things yet. Thanks.

 

[OttoMatic]

Hi there,

Behringer 2500 or another pro style amp that would have sub outputs

The Behringer doesn't have "sub outputs" per se. It's just a basic two-channel amp that has a lot of power (I'm using one for sub duty).

I only have a 100 watt per channel Yamaha stereo amp

Is that an integrated amp? Receiver?

Can I parallel my existing speaker outputs and go direct to a powered sub? Would I just change my impedence switch to 4 ohms?

Usually when you go into a power sub's speaker-level inputs, you don't need to worry about that type of impedance matching. The sub input will be very high impedance and will draw negligible current. The "very high" impedance in parallel with your existing speakers will present a load that is very close to your existing speakers. So, no worries there.

Alternatively there is a line level output on my amp that is for going into an effects box or equalizer.

So, is this a variable line out? That is, does it track with the volume knob? Or is it a tape loop? If it's an output that tracks with volume, you could send it to a BASH amp or a pro amp like the EP2500.

I think you are working with a couple viable options. Either way will "work."

One thing that hasn't been mentioned here is bass management. A BASH amp may well have a low-pass filter (and perhaps a high-pass filter for the mains as well). But if you're going to use an EP2500, you'll need some means to cut the high frequencies out of your sub's signal. If your integrated/receiver won't do it, then you'll need to get an external box that will.

So you'll go receiver->crossover->EP2500->sub. There are a bunch of crossovers that will work. I'm using a Behringer BFD1124P as a low-pass filter for music listening (when I can't use the bass management of my preamp). You can find these on eBay for well under $100. In addition to them being usable as a low-pass filter, they are extremely effective as equalizing your sub signal as to work on the issues of room modes.

There's some good info on the BFD here.

Since you're in Canada, you might consider Mach5 as a driver source. I'm using four of the MJ-18s in an IB, and they are effective.

Anyway, I think I went on rambling a bit, but it's a start for ya. Good luck!

 

[bluejay]

OttoMatic,

Thank you for your kind response. I'll answer what I can.

The Behringer doesn't have "sub outputs" per se. It's just a basic two-channel amp that has a lot of power (I'm using one for sub duty).

Then I would need to figure out what to do. Buy something other than the Behringer that has subs out, (stereo?), or get the combination of boxes needed to interface with what I have.

Is that an integrated amp? Receiver?

The Yamaha is an integrated amp. It has the variable line out that tracks with the volume control, however, if you do not return a signal it becomes just a pre amp. If you return a signal you keep the amp portion working along with what you plugged into. If the BASH provided a return signal it would be great. If not, I would need another box to do so, or not use it.

Usually when you go into a power sub's speaker-level inputs, you don't need to worry about that type of impedance matching. The sub input will be very high impedance and will draw negligible current. The "very high" impedance in parallel with your existing speakers will present a load that is very close to your existing speakers. So, no worries there.

Thanks for explaining that. It is looking like a single BASH or something similar would be easier in this context. I guess you can adjust the plate amp to respond to your changing volume? Dial it in to what you like and then leave it?

But if you're going to use an EP2500, you'll need some means to cut the high frequencies out of your sub's signal. If your integrated/receiver won't do it, then you'll need to get an external box that will.

I would like to figure out how to do these things even if I choose the other way. If I lined out the Yamaha without return signal it would become a pre amp only. I would still need a crossover box or similar. Maybe there is another preamp that would do it all? I also need to keep track of balanced and unbalanced inputs and outputs. I believe all my consumer level stuff is unbalanced, CD, tape, tuner, TV, Xbox, etc. Behringers, Crowns, QSCs, etc. are usually working with balanced inputs? Are there any favorite or popular ways to get them liking one another, a mixer?

Thanks again, got to keep reading.

 

[bluejay]

Thanks for the Mach5 tip. They are closer to me and have good looking items. Are they comparable to anything else?

 

[bluejay]

I will be waiting to hear from Otto or other folks. In the meantime I am considering the Reckhorn A400 subwoofer amp.

found here, http://www.reckhorn.com/index.php?ln=en&prod=a400

I am no expert but it seems to address most of my needs. It has equalization capabilities built in and other adjustments. Kindly check out the specs to see if I have missed something. From the above discussion you will note I am a bit lost on the subject of subwoofery.

 

[WmAx]

For bass management for use with an EP2500, get a Behringer CX2310 2 way active crossover. It is a 4th order Linkwitz-Riley with infinite variable xover frequency and individual gains. It can be had for $90 new, and it is an excellent crossover made with vert high quality components(even the switches and pots are very high quality), and with quiet operation. Use your pre-amp outputs in full band to the CX2310, and use the low pass outputs to the EP2500 and the high pass outputs to your main speaker amplifier(if you are using component amplification).

Note: If you get an EP2500, don't try to use the mono input option when in stereo amplifier mode, even though this is an option on the DIP switches on the back. Many people report that it won't match the L and R channels correctly in this fashion. If using in stereo operation(non bridged), feed each L and R input a signal.

-Chris

 

[bluejay]

Thanks WmAx

Sounds like a good way to go. I'm going to price that equipment up here and find out if there will be any surprises. Especially valuable is the dip switch alert.

Something that comes to mind. Would a processor like the 2024 or 2496 work in place of the CX2310? The reason I ask is it would be cool to have reverb ability. Any pros or cons with a processor setup?

 

[OttoMatic]

http://www.sweetwater.com/c861--Unbalanced_Cables_RCA_to_XLR

OttoMatic,

The Yamaha is an integrated amp. It has the variable line out that tracks with the volume control, however, if you do not return a signal it becomes just a pre amp. If you return a signal you keep the amp portion working along with what you plugged into. If the BASH provided a return signal it would be great. If not, I would need another box to do so, or not use it.

What happens if you split the signal coming out of the amp? Just use a simply Y-splitter and feed half of it to an external device (your sub amp or crossover) and the other half goes into the return path? There might be some level issues, but I'm pretty sure you could get away with it.

It is looking like a single BASH or something similar would be easier in this context. I guess you can adjust the plate amp to respond to your changing volume? Dial it in to what you like and then leave it?

Yeah, the BASH will be easier, especially if its designed specifically as a sub amp; all the relevant controls will be in place. It'll be more flexible in the beginning, but you might be looking for more down the road. I would personally go with the external device path, but it's up to you.

Both the BASH amps and the EP2500 will have gain controls of some sort. So, yeah, you set your levels and get everything the way you like, and then just leave the controls on the sub amp. The sub will just follow volume from your preamp and it'll just become part of the system.

I would like to figure out how to do these things even if I choose the other way. If I lined out the Yamaha without return signal it would become a pre amp only.

Yeah, if you're simply using it as a preamp for a sub. I probably wouldn't do that; I don't think there's a need. You'd still have to use another external amp to drive your mains. I'd just keep the Yamaha as you have it now (I'm 99% sure that I'd try to split the output as described above).

I would still need a crossover box or similar.

Yeah, unless you're using the BASH or another sub amp with a built in crossover.

Maybe there is another preamp that would do it all?

Sure, there are tons. Almost any home theater preamp will do what you want, as far as bass management (sub to main crossovers and such). If you are only interested in two-channel listening, I believe the Outlaw RR2150 is a great two-channel piece that still uses bass management. If I were going to put together a simple two-channel system, I would definitely consider that receiver.

I also need to keep track of balanced and unbalanced inputs and outputs. I believe all my consumer level stuff is unbalanced, CD, tape, tuner, TV, Xbox, etc. Behringers, Crowns, QSCs, etc. are usually working with balanced inputs? Are there any favorite or popular ways to get them liking one another, a mixer?

I think most of them will take an unbalanced signal if you just have the proper cabling. There are myriad adapters and such that you can buy. Consult with the manuals first. I believe you'll need an RCA on one end and an XLR on the other end. Connect the RCA's signal line to XLR pin 2. Connect the RCA's shielding to the XLR's pin 1 and pin 3. You may run into some level issues, but I think you'll generally be OK.

Here are some cable examples that will do what you need.

A solution that will handle the level issues between consumer and pro gear is an ART CleanBox. I'd wait on that, though, and see how it goes without it. I've use both balanced and unbalanced signals to the Behringer 1124p with no problems.

Good luck!

 

[OttoMatic]

Thanks for the Mach5 tip. They are closer to me and have good looking items. Are they comparable to anything else?

I'm not sure... I bought them because I was building an IB and I wanted something cheap. I figured that I could make up for any natural low end extension by simply piling on more drivers. I only have experience with my IB; I've never ever heard any other. But I think I was right in that more is better (though I could certainly get away with only two, without question).

All in all, they're good, cheap drivers. If I had it to do over again, I'd buy better drivers just to see the difference. Maybe this winter if I get bored and have the time. I'm sure my wife will NOT understand, so maybe not.

I'm no good with all the driver parameters. I'm just not interested in becoming a speaker designer, so I can't help there. For you, if you're making a single-driver sub in a box, you might have to figure those things out. There are some sub design softwares available that will certainly help you out with that -- I think you just generally input your driver parameters, your box size and port size and out comes a frequency response. Should work something like that...

In the meantime I am considering the Reckhorn A400 subwoofer amp.

I like the look and features of that amp, in general. I'd probably want more power, but who doesn't? If you think it suits your needs power-wise, consider it. I haven't heard of the brand, so that might worry me a little. For $US 300, I'd opt for the EP2500 (of course, you then have to buy crossovers, etc.). Just my $0.02 on that one...

Would a processor like the 2024 or 2496 work in place of the CX2310? The reason I ask is it would be cool to have reverb ability. Any pros or cons with a processor setup?

WmAx is right about the 2310. Not a bad piece, and I think it'll do all you need for crossover duties.

If you're asking about the DCX2496 (not familiar with the 2024), I think it'll be overkill, but it will work. IIRC, it's a three channel crossover, and you really only need one or two. It does have the other processing power, as noted. If you want reverb, then it'll get it done for you. However, I can't imagine that I would ever want reverb in my sub path, but I'm a pretty simply listener, especially in two-channel mode. If you dig it, then it's in that box.

I know it may look overwhelming, but I'd still consider the BFD 1124. You can use it as a simple low-pass crossover, but it also has parametric EQ functionality. I've found that to be critical to the sub experience.

Good luck!

 

[WmAx]

I know it may look overwhelming, but I'd still consider the BFD 1124. You can use it as a simple low-pass crossover, but it also has parametric EQ functionality. I've found that to be critical to the sub experience.

Good luck!

It is best to have a single unit to control the low pass(to sub) and high pass(to mains) in order to reduce potential for confusion/errors. The DCX2496 is an excellent tool, and would also allow customized sound quality changes; for example, one can shape the sound output response to any degree of subjective 'tightness' that they so desire by playing with the final output curve to the subwoofer.

If cost is getting to be an issue, though, the cx2310 is an excellent piece of hardware, but does not have the signal shaping capabilities of the DCX2496. Though, one could also consider the additional investment into a DCX2496 as a future proof tool. One could go ahead in the future and make DIY 3 ways, using the DCX2496 as the xover system.

-Chris

 

[bluejay]

Thank you so much.
I will preface to say that unfortunately cost might be a factor this time and saving $100 or $200 might be the deal breaker this time. If I want to live without a sub system for a year I will be better able to go whole hog. That being said;

What is the general difference between a parametric equalizer like the 1124 and the way the 2310 works by crossing over and having Linkwitz-Riley filters. Just to let you know, when we use high pass and low pass terminology, I get mixed up. This is because my integrated amp is like a pre amp and a power amp in one box with a jumper between. It will send all the signal to the box I buy. The box has to remove highs, (is this low pass)? After high removal the signal is ready for either the Behringer 2250 or the Bash amp. The Bash doesn't need the box because it can accept full signal, either line or speaker out, and filter highs out itself, (low pass).

Now if I want to use a 2500, I need a signal for my stereo pair. Coming out of all of the boxes described, 2310, 1124, or 2496, is a full line signal that is able to be adjusted and reinserted to my Yamaha, yes/no? If that is so then the adjustability is the comparitor, 2496 - reverb, 1124 - parametric, 2310 - Link-R.

Excuse me for a second. If I have made an incorrect assumption above, I will be foolishly carrying on with it.

A Bash or other plate amps have different options built in. One of these options is high pass? Is that low power or amplified? Plugging an incomplete signal back through my Yamaha would not be that good because my satellites are full range JBL EON 15's. If I would use something without a proper return signal - I should just use a Y connector to provide one myself.

If I want or need to get a Reckhorn 400, on the back of that unit I see these connections.
Low input - connect to my pre amp out?
Speaker input - use if I did not have pre amp out?
Subwoofer output plus and minus - go to sub(s), mono only
Sat Out L and R - not sure here? it could be full signal, high passed, amplified? If not good in my case then I would use the Y connector method

Anything else bothering me? I would prefer to not just be constrained to using the 2500 for subs only. It would be nice if it could run my full range speaker set too. I suppose it can if I do it all different.

 

[OttoMatic]

What is the general difference between a parametric equalizer like the 1124 and the way the 2310 works by crossing over and having Linkwitz-Riley filters.

Sure. In general filters can cut high frequencies (then called a low-pass filter or LPF), they can cut low frequencies (then called a high-pass filter/HPF) or they can notch out certain frequencies (called notch filters -- imagine just cutting out the range of 1,000 to 2,000 Hz, that'd be a notch filter). No filter is perfect, so there are slopes associated with how much cut there is as compared to the particular frequencies.

The L-R circuit is just a clever 4th order crossover, and I believe it's implemented in the analog domain. 4th order means that it will roll off the frequencies at 24dB/octave (this is generally good). The 1124 is all digital and its filters can be set to different slopes.

In general, and for most applications, you want to cut the high frequencies out of your sub range, and you want to cut the low frequencies out of your mains' range. The two should then blend together nicely at the crossover point. There's more to it than that, but those are the basics.

Here's a generic description for LPF from Wikipedia.

The difference between the 2310 and the 1124 is that the 2310 is a crossover while the 1124 is a parametric EQ (that can be used as a simple LPF if set up properly). That means that the 2310 is used to take in a full range signal, and then output a HFP signal (then sent to your mains' amplifier) and a LPF signal (sent to your BASH plate or your EP2500). The 1124 will not do the crossover stuff quite like that. It will take in whatever signal your send it, and it will alter it to your specifications -- it can notch a little here and boost a little there, all in an effort to get your frequency response as flat as you want (that's usually the goal anyway). If you set it up to crush all frequencies above, say, 40 Hz, then you will be using it as an LPF, although that's not really its intended usage (that's what I'm doing in one case).

Just to let you know, when we use high pass and low pass terminology, I get mixed up.

No problem; there's a lot of terminology and new concepts to be learned!

This is because my integrated amp is like a pre amp and a power amp in one box with a jumper between. It will send all the signal to the box I buy. The box has to remove highs, (is this low pass)?

Yep.

After high removal the signal is ready for either the Behringer 2250 or the Bash amp. The Bash doesn't need the box because it can accept full signal, either line or speaker out, and filter highs out itself, (low pass).

That sounds correct.

Now if I want to use a 2500, I need a signal for my stereo pair. Coming out of all of the boxes described, 2310, 1124, or 2496, is a full line signal that is able to be adjusted and reinserted to my Yamaha, yes/no?

No, you won't want to send that signal back to your Yamaha's input, or your mains. It'll be cut off for bass frequencies.

I would split the output of your Yamaha, loop one back into the unit itself and send the other one to the sub setup. I'm 99.9% sure that'll work, and it'll be the easiest and cheapest method.

If that is so then the adjustability is the comparitor, 2496 - reverb, 1124 - parametric, 2310 - Link-R.

Not sure what that means.

A Bash or other plate amps have different options built in. One of these options is high pass? Is that low power or amplified? Plugging an incomplete signal back through my Yamaha would not be that good because my satellites are full range JBL EON 15's. If I would use something without a proper return signal - I should just use a Y connector to provide one myself.

If I want or need to get a Reckhorn 400, on the back of that unit I see these connections.
Low input - connect to my pre amp out?
Speaker input - use if I did not have pre amp out?
Subwoofer output plus and minus - go to sub(s), mono only
Sat Out L and R - not sure here? it could be full signal, high passed, amplified? If not good in my case then I would use the Y connector method

All the high-pass stuff that's offered in those units may not be terribly configurable. Without reading the manuals, it'd be hard to say exactly what or how they've implemented. It may follow the frequency of the LPF, it may apply to a powered signal, or may not, etc. I'd opt for the 2310 over that business.

If you're going to be doing mostly music listening, I'd probably recommend trying to blend the sub with the mains while allowing the mains to run full range (i.e., no HPF on the mains).

Anything else bothering me? I would prefer to not just be constrained to using the 2500 for subs only. It would be nice if it could run my full range speaker set too. I suppose it can if I do it all different.

I think you're pretty much going to have to dedicate that amp to sub duty or mains duty -- you'll have to pick one. That's because the signal that's feeding the amp will apply to only one or the other. Unless you go to passive crossovers, and I don't think you want to do that.