Advantages of having 15" subs with 15" tops?

[palantir]

Evening all

Is there any significant advantage to running 15" subs if I have main speakers having 15" drivers & compression horn?

 

Both subs & mains are 300w rms.

 

I appreciate there would be more bass, but would you expect the subs to go lower than the mains?

 

Pete

[saturnx21]

I appreciate there would be more bass, but would you expect the subs to go lower than the mains?

 

That would depend on the Driver/Cab.

 

Personally I would have either 12" tops with 15" bins or 15" tops with 18" bins but that is not the be all and end all it depends on the type of work you are doing, the venue etc. etc.!!!

[Bobbsy]

As saturnx21 says, it's not possible to be specific without knowing the details of the actual gear you have. However, some generalised comments:

 

In a full-range cab with a 15" sub, that driver is required to reproduce a far wider range of frequencies--I'd guess the crossover frequency will be between 1.5 and 2 kHz. This has a couple of effects. First off, very low frequencies don't always "play nicely" with their higher brothers and this can affect the clarity of sound, particularly at vocal frequencies. Alas, adding a sub won't fix this issue. Second, in terms of "power per octave", you'll have considerably less energy for the true sub bass frequencies. A sub, in tandem with a crossover that restricts it to frequencies below, say 125 Hz, will give you substantially more bass energy with a 300 watt amp than a full range at the same power.

 

So, yes, there could be some advantages.

 

However, I have to say that, unless you have to work without subs, I'm not a fan of using 15" drivers in a full range cabinet. In terms of vocal clarity, 12" drivers will usually do a better job--and give you an easier to handle box-size as well. True, they don't have quite the bass thump, but that's what the subs are for.

 

Bob

[The Boogie Man]

As Bobbsy said.

And a nice idea ( if you have the cabs you are talking about, or are you just wondering about adding some bass cabs to your mains? ) might be to get an active x/over and tri amp the stack. But the mid range cab would be better as a 12" as vocals get sort of loose and flabby through anything bigger.

[Jivemaster]

A 15inch sub driver is a different item from a 15inch full range driver. Properly configured a bass driver will give better bass than a 15in full range. Also it can be very helpfull to divide the power needed for good bass via two drivers well configured, rather than one driver being thrashed and trashed. Do sort out the crossover carefully.

 

As a system, I'd not like to have vocals through a 15 but 12 or 10s for articulation.

[palantir]

Thanks a lot, chaps:

You've confirmed pretty much what I had gleaned from previous posts to the forum, but it's always good to get things clear in my bonce - not always easy these days

 

The reason I was asking is that there was a pair of Ohm 15" fullrange & a pair of 15" subs, on ebay; I was intending to bid on the fullrange as they were offered with courier delivery (not common with 2nd hand speakers) but the bu&&er has withdrawn them all early.

 

I wasn't sure about the subs, but it's all vapourware now anyway :( .

 

The problem is, if I get a pair of 12" & don't get subs in time for the next show, I won't have a great deal of oomph; but I think that's the way to go - After all, there's no rush - I shouldn't need them until July.

 

Thanks again

 

Pete

[Sirch Sound]

Hi, remeber theres still nothing wrong with running 15" Full range with 18" bins, I admit it would not be my preferd choice as im not too keen on the sound of 15" for vocals and instruments, I find a 12" is generaly alot more crisp and clear, but it dosent stop hundreds of thousands of people running 15" fulls with 18" subs. Its your choice though really, you need to get a demo of some different set ups and decide which one you prefere the sound of and which is going to be best for your application.

 

Rich

[Rich]

And just remember that 15" reflex bins (if well designed) will give you an f3 point of 40Hz, will have a better transient response than 18"s, will be lighter, smaller, and will probably only be about 3dB quieter.

[paulears]

For the last year, for a specific reason I've had two different systems side by side - one has 12" drivers in the tops with 15" subs. and the other has 2 x 15" drivers in the tops with 18" subs. The 12" top boxes, without the subs (all this is bi-amped - letting me 'fiddle') are great for clarity - but for music they really need the subs which are x-over'd to take over where the 12" drivers run out of steam. The big 2 x 15" cabs on their own, certainly have plenty available at the bottom end, but are less - not sure of a word for this - but 'hi-fi' suits. Add the 18" subs and they really move the air. From the back of the room, I've got control of all this from the desk, so can A/B easily. If it's rock and roll, or modern stuff, the 2 X 15" and 18" subs are the most normal sounding. For middle of the road material, and things like big band/rat pack style material the smaller drivered system is nicer to listen to the the LA 325s, which have 'something' missing in the middle, as others have said

[mervaka]

I'm always tossing up between the benefits of having dual driver tops. is there a reason why there I seem to find more 2x15" tops in the market than 2x12"s?

[Rob_Beech]

2x15 + HF is generally more popular due to them working better as a full range box. (ie if you don't want subs aswell). That's not to say there aren't 2x12 boxes out there. Generally in the higher end of the market you'll find the 2x12 boxes.

[Sirch Sound]

Yep, as rob said, the general idea of the 2x15" + HF cabs is so that you can take 1 pair of speakers to your gig and dont have to worry about bins or anything, hence why there is 15" drivers to reproduce the bass better. The 2x 12" cabs are very rare, infact I carnt think of any?? The only cabs I can think of with 2x 12" drivers are one's that include another driver, wether its a 6", like the RCF 4Pro 6001 or a 10", like a couple of the EAW's, the models escapes me at the moment.

 

But yes, you can get 2x12" +HF, however I just carnt seem to think of any at the moment! Helpful, arnt I?!

 

Rich

[mervaka]

there is the fohhn RT6, and I think EV also do a couple of 2x12"s. I know they're out there, just wondered if its just the same rules that apply as between 1x12 and 1x15 tops, or whether there were any other reasons (like throw distance?)

 

the RCF 6001 looks tasty, albeit a little above and beyond what I can afford!

 

oh, and the ohm TRS rigs use 2x12s I think too! I love the TRS, I just dont own one!

[palantir]

It would be great to be able to listen to several setups before deciding what to buy but, as Merv knows, it ain't easy when you're 200 miles beyond anywhere ;) .

 

All I seem to hear is the local DJs' rigs & I wouldn't give any of them house-room.

 

Ho-hum....... as Mr. Micawber said, Something will turn up.

 

Pete

[Sirch Sound]

Yer, the 6001's sound pretty sweet, however they weigh slightly more than the moon! But fairly compact for all of the drivers that are shoved inside them! They do give a really nice warm sound though, I supose when you have so many drivers it works them alot less to be trying to reproduce everything through 2, and therefor the drivers are always in there "comfort zone"(Forgotten the word!) , and therefore alot nicer sounding.

 

Rich