Another Question - Running only one sub

[Joe]

Hi! I've got a pair of Class D speakers and a Prosound 1000 amplifier (gotta say it's not half bad). I'm really not getting the full sound i would like from just the Class D speakers alone, and I'm considering adding an active sub such as the QTX QT15SA (not the best but gotta start somewhere). 2 questions:

1.I'm only going to be using one sub, what should I do in regards to the signal i feed into that subwoofer. Could i get away with just feeding in say the left channel of audio, or do i need to use a small mixer or something to feed in both the left and right as a mixed down mono signal.

Do i need to purchase a crossover? Ofcourse an active sub would have one, but do i need to filter just the mid and highs to the satellite speakers?

Thanks!

[Daryll]

Hey Joe ( could been a song here somewhere....:p )


Loads of permutations here , what mixer are you using , some have a summed mono out ( Sub out ), mixers such as the denon X-500 has one , if that is the case , just a feed from the sub out on the mixer to the QTX QT15SA in , main out from the mixer to your amp and speakers as per usual.
looking at the rear panel on the QTX QT15SA , it appears to have an XLR in and thru . if that is the case then its mono in and out...:(.
however another option , and one I use ,is a passive sub ( two for me) , two amps , one for subs and one for tops , plus a 2 way crossover , best of both worlds , you have a built in backup in one amp goes , plus loads of control over the crossover point and input and output levels , using a passive 15" sub , you could use a SMPS amp in bridge mode, such as the W-audio Horizon 800, specs.

Stereo power: 2 x 250W @ 8ohms
Stereo power: 2 x 400W @ 4ohms
Bridge power: 800W .

cheers

Daryll

[Excalibur]

1.I'm only going to be using one sub, what should I do in regards to the signal i feed into that subwoofer. Could i get away with just feeding in say the left channel of audio, or do i need to use a small mixer or something to feed in both the left and right as a mixed down mono signal.

Do i need to purchase a crossover? Ofcourse an active sub would have one, but do i need to filter just the mid and highs to the satellite speakers?

Thanks!

Joe, the sub you've chosen has good and bad points for your chosen purpose. Do you intend just to use one for reasons of space in your motor, or lack of notes in your wallet? The reason I ask is that while the QTX has a crossover built in, it's one channel only. That makes it slightly tricky to wire up. As yet, I haven't found anything similarly priced with two channels. For anyone wanting to use one sub only, an active one is the easiest way, especially if it has the two channel crossover fitted. You'd run the two cables from your mixer outputs to the sub inputs, and from the two filtered outputs back to the input of your amp running the tops.

That's the ideal scenario, but there are other options, although none as simple and efficient. If you can afford and transport two of the QTX subs, that's ideal. You run the left mixer channel to the left sub, and the output from that into the left channel of the top amp. Same with the right hand side.

If that's not an option, an active crossover may be your best bet. Cheap one (http://www.ebay.co.uk/itm/Citronic-CX23-Active-Crossover-2-3-Way-Audio-Band-PA-System-DJ-Disco-Install-/170900450701?pt=UK_AudioTVElectronics_HomeAudioHiF i_Amplifiers&hash=item27ca75ed8d) The thing is, that will be nearly as expensive as a second sub, so plenty for you to think about.

Your problem can be solved in many ways, we just need to find the best one for you.

[Joe]

Thanks so much for your help!

If I did buy a pair of the QTX subs, wouldn't I still need a crossover? Isn't the output just a thru rather than a high pass?

[Joe]

http://www.thomann.de/gb/the_box_hpf1.htm

This looks like it would be just the ticket. Thoughts?

[Excalibur]

http://www.thomann.de/gb/the_box_hpf1.htm

This looks like it would be just the ticket. Thoughts?

You live and learn. I've never seen one of those before. It seems to fit the bill, the only thing that worries me is that it says it's passive. ( No power inside it. That's not encouraging. )

I know nothing about them, but on paper it seems to be what you need. Let's hope someone knows more about this type of thing.

As I asked before, is the main reason for not using two cost, or space? Two of the QTX or Skytec come in only slightly dearer than one plus this box.

EDIT: As far as I can see, the output is filtered. If you could see one in a shop, you'd soon find out. If that were the case, you wouldn't need a crosover.

[cauthers]

Like has been said before there's a few options open to you, depending on transport space, budget etc

I myself use a similar setup to yours:

2 x passive tops
1 x active sub (funnily enough the qt15sa)

The way i did it was by purchasing a mixer with a crossover built in, the behringer ddm4000. This way it's all done on the mixer rather than needing extra rack space for a crossover unit, extra plug sockets to power it, no messing on the back of the sub mid-gig to change the x-over frequency if you don't think it sounds quite right, etc

Alternatively another 2 options would be:

you could go from the mixer to the sub, then from the sub to your amp (running in bridge mode if your amp allows) It'd mean that you'd be running in mono rather than stereo but it wouldn't make a huge difference.

Or you could go from mixer - to sub - to amp using a jack to dual jack splitter. Again it would mean mono but it saves you running your amp in bridge mode.

Just another 2 ideas to add to the already great answers given before

[Excalibur]

Like has been said before there's a few options open to you, depending on transport space, budget etc

I myself use a similar setup to yours:

2 x passive tops
1 x active sub (funnily enough the qt15sa)

The way i did it was by purchasing a mixer with a crossover built in, the behringer ddm4000. This way it's all done on the mixer rather than needing extra rack space for a crossover unit, extra plug sockets to power it, no messing on the back of the sub mid-gig to change the x-over frequency if you don't think it sounds quite right, etc

That's another viable way of doing it.



Alternatively another 2 options would be:

you could go from the mixer to the sub, then from the sub to your amp (running in bridge mode if your amp allows) It'd mean that you'd be running in mono rather than stereo but it wouldn't make a huge difference.

Or you could go from mixer - to sub - to amp using a jack to dual jack splitter. Again it would mean mono but it saves you running your amp in bridge mode.

Just another 2 ideas to add to the already great answers given before
Unless I've missed something, this isn't a good idea. You'd have to combine the left and right outputs from your mixer into the single input on your sub, and then either run the top amp in dual mono ( where it usually feeds the left hand side toboth channels) or split it again, after having previously combined it. Two active subs or a crossover seems way easier and safer.

[SamV]

My suggestion would be to get a crossover unit, something like a cheapo Behringer Super Xpro. That way it will give the sub the signal it wants, and the tops the signal they want so there's little overlap. It will also let you manage the subwoofer level to help balance things nicely.

[Joe]

Anyone know of any reasonably priced crossover's that can do a mono output for the sub? All of them are intended for dual sub use.

Also, I'm now considering the slightly more ghetto option - running a pair of subs in parallel with my tops. Currently i'm just using a pair of ProSound 12" speakers with the Class-D speakers to get extra bass response (Jac10s on their own just don't cut it). Thoughts?

[SamV]

Most of them should be able to sum the mono to the sub as that's pretty standard. Berry Super X Pro is cheap.

[Daryll]

I actually use this one , 18 months with out a glitch.

http://www.bluearan.co.uk/index.php?id=SKT170929&browsemode=manufacturer

Daryll

[hammy]

Look in the for sale section, I`m sure there are 2 decent 600w subs for sale at a really really good price.:)

[Excalibur]

(Jac10s on their own just don't cut it)
They won't. They're mid-high cabs, really. Your best bet is to somehow get the low frequencies out of that amp and cabs somehow. That will give them a much easier life, and sound better.

Here's the manual for the Behringer. (http://www.behringer.com/assets/CX2310_P0132_M_EN.pdf) I believe it's possible to use the single sub output and the two high outs in 2way stereo mode. You will get the best results running something like this to control the frequency split, and better still with two subs. Best of luck.

[cauthers]

That's another viable way of doing it.


Unless I've missed something, this isn't a good idea. You'd have to combine the left and right outputs from your mixer into the single input on your sub, and then either run the top amp in dual mono ( where it usually feeds the left hand side toboth channels) or split it again, after having previously combined it. Two active subs or a crossover seems way easier and safer.

Totally agree that it's not an ideal way to do it, but it's one solution of doing it with the kit he already has. If the mixer output is in mono mode before sending the signal to the sub it would just be mono on all 3 speakers, and providing that the amp was capable of running bridge at 4ohms (im guessing both tops are 8ohms so 4ohms combined) it shouldn't cause any problems? Could be wrong mind, wouldn't be the first time lol

[Excalibur]

Totally agree that it's not an ideal way to do it, but it's one solution of doing it with the kit he already has. If the mixer output is in mono mode before sending the signal to the sub it would just be mono on all 3 speakers, and providing that the amp was capable of running bridge at 4ohms (im guessing both tops are 8ohms so 4ohms combined) it shouldn't cause any problems? Could be wrong mind, wouldn't be the first time lol

Reckon you are. Legendary Prosound amps won't run bridged into a 4ohm load. No way. Why bridge it anyway? Either use a splitter to feed both channels, or run dual mono ( if there's a switch on the back to do this. All mine have, but they're not Prosound. :D

[Joe]

My Prosound amp is the older Carlsbro built model, so no bridge mono. The ideal, which is a little over budget, is this guy: http://altoproaudio.com/products/tssub12

Looks to be just the ticket. It's got left and right inputs and outputs, and a highpass filter. Anyone had any experience with Alto gear?

[Joe]

Pretty much crunchtime right now. Deciding between the QT15SA and the passive Thomann cross over vs the Alto TSSUB12. Would you guys rate the QT15SA enough bass re-enforcement for my Jac10s?

[Excalibur]

Pretty much crunchtime right now. Deciding between the QT15SA and the passive Thomann cross over vs the Alto TSSUB12.

Right, I've got no personal experience of either. Alto stuff tends to be budget stuff, which does what it says on the tin. Personally, I'd go for the Alto, mainly because of the connections.

[SamV]

The Alto is better made and the better brand out of the two, and if I'm not mistaken, 2.5x the price?

Anyways, I'd go for the Alto as at least they state rough specs and looks good and well made.

[cauthers]

Not had any experience with the alto gear but I've seen a LOT of good reviews on the truesonic full range speakers they do. Ive got a qt15sa and it's surprising how much of a difference its made to both the quality and volume, took a bit of a punt on it really with never having heard one before but glad i did. For the cash you can't go wrong, the only downside I've found so far is that the controls aren't recessed on the actual cab so you have to be a little more careful when transporting them.

If there are any dealers near to you it'd probably be a good idea to see if they stock either so u can have a demo?