Looking to build my own 2x15 800w bass cab

[RIM Basses]

Hi Guys,

Ive decided to try and build myself a 2x15 bass cab, got some celestions direct at trade and looking to use 18mm Baltic Birch. Im gonna look to build the cab around 40 x 24 x 17 inches deep. All hardware from Penn elcom etc, should be interesting and the cabinet will be dark stained finish wise. Alex if you are about could you get back to me with any help on ports etc, I dont know anything about specs etc. I built a 15 inch cab a few year back which sounded great with my tech TVM600 combo, just want to go the no frills approach old school vibe. Think Sunn 2x15

[url="http://www.richbriere.com/images/wpe48765.gif"]http://www.richbriere.com/images/wpe48765.gif[/url]

Got the speaker, looking to start the cab in the next few weeks, any help advice would be cool. Also check out the verellen cabs for the vibe im looking to style my cab on.

Cheers,

Robbie.

[Mr. Foxen]

Sounds cool, what are the Celestions? Gonna use WinISD for the port tuning?

[RIM Basses]

Hi Mate,

They are Bn15 400x neo drivers, i dont understand the winisd website, im old school. i might just build the cab and try with a couple of large 4 inch ports at first. If it sounds good then im happy. Doing a serch told me the bn15 cones are better in sealed cab, gonna be interesting. I was going to take the purplechili 215 off Mike but decided to try and build my own.

R.

[RIM Basses]

Hi Mate,

They are Bn15 400x neo drivers, i dont understand the winisd website, im old school. i might just build the cab and try with a couple of large 4 inch ports at first. If it sounds good then im happy. Doing a serch told me the bn15 cones are better in sealed cab, gonna be interesting. I was going to take the purplechili 215 off Mike but decided to try and build my own.

R.

[AlanP2008]

[quote name='RIM Basses' post='743600' date='Feb 12 2010, 11:44 PM']They are Bn15 400x neo drivers, i dont understand the winisd website, im old school. i might just build the cab[/quote]

Old school eh? And spurn the use of tools like winisd? I guess you will be carving the panels for your cabs with your bare hands and a stone axe?

Sorry, I'm being facetious... it is an unattractive trait...

But it is very worthwhile understanding *free* stuff like winisd, and study speaker characteristics a little...

In particular, the unique challenge in getting a decent bass response in a sealed box is to build a large enough box (in fact you will need an absolutely gigantic box....)

The challenge in a tuned or sealed enclosure (assuming the box is big enough) is in choosing a speaker that will both give you the response you need, and from a practical standpoint, not destroy itself when trying to get decent power levels for the lowest notes - 40Hz ish for low E, 31Hz is for low B... The key parameters in that are the Xmax and Xlim parameters... Xmax being the maximum [u]design[/u] speaker excursion at the particular power and frequency you are considering, and Xlim being the point at which the voice coil is likely to sustain irreparable damage...

The spec sheet for the Celestion Neo speakers don't actually state Xlim, but the value for Xmax of all of those I have looked at is [u]much too low[/u] for credible use in a bass cab... (and yes, I know some well rated cab manufacturers use them...)

The Bn15 400x has a stated Xmax of 4mm. That compares very poorly with most of the best (for example) Eminence bass speakers ... The Kappalite 3015 LF has an Xmax of 9.6mm, and an Xlim of 17mm, which is really excellent...

winisd is able to show you the frequency response of your proposed cab design, determine the porting, and see the real effect of the mechanical limits at various power levels, which should allow you to understand how robust (or fragile) will be your investment in your bass speakers...

... or you could just build them and see - but the likelyhood of being happy with the result are (imho) pretty slim...

Alan

Edited February 13, 2010 by AlanP2008

[Mr. Foxen]

If they want a sealed cab, stick them in a sealed cab, they just won't be very bassy. Good for a roaring valve amp though.

If you want the ported option, go for the kappalite 3015 (nonLF). Or for the Doom option, build the Celestions into a sealed cab, and make another cab with a Kappalite 3015LF for epic bottom, and run a SS power amp into that, and rag a power amp into the sealed 2x15. This is pretty much my plan.

[AlanP2008]

[quote name='Mr. Foxen' post='743998' date='Feb 13 2010, 02:04 PM']If they want a sealed cab, stick them in a sealed cab, they just won't be very bassy. Good for a roaring valve amp though.

If you want the ported option, go for the kappalite 3015 (nonLF). Or for the Doom option, build the Celestions into a sealed cab, and make another cab with a Kappalite 3015LF for epic bottom, and run a SS power amp into that, and rag a power amp into the sealed 2x15. This is pretty much my plan.[/quote]

As far as I can see from the spec sheet, the most significant differences between the 3015 and the 3015LF are:

i) 3015 Xmax=5.9mm, Xlim=11mm, 3015LF Xmax=9.6mm, Xlim=17mm (the LF will take quite a lot more power at low frequencies before it cracks up)
ii) 3015 sensitivity= 100.8, 3015LF sensitivity=98.4. (The LF is *good*, but the 3015 is *excellent*)

The other point one might spot is that the 3015's on-axis response goes up higher, but as I have seen often pointed out here, the off-axis response (which is much more significant) is dominated by the fact that both of these are 15" speakers, and both will both need some kind of mid-range driver to give them any kind of off-axis top-end (ie. anything much above 1000Hz) at all (but your taste and/or style might not need that).

winisd suggests that the LF will give a bit more bass extension than the non-LF.... but in the end, you pays yer money and you takes yer choice - they both seem to be excellent speakers for bass to me (as are the 3012s).

Alan

[Mr. Foxen]

[quote name='AlanP2008' post='744036' date='Feb 13 2010, 02:52 PM']As far as I can see from the spec sheet, the most significant differences between the 3015 and the 3015LF are:

i) 3015 Xmax=5.9mm, Xlim=11mm, 3015LF Xmax=9.6mm, Xlim=17mm (the LF will take quite a lot more power at low frequencies before it cracks up)
ii) 3015 sensitivity= 100.8, 3015LF sensitivity=98.4. (The LF is *good*, but the 3015 is *excellent*)

The other point one might spot is that the 3015's on-axis response goes up higher, but as I have seen often pointed out here, the off-axis response (which is much more significant) is dominated by the fact that both of these are 15" speakers, and both will both need some kind of mid-range driver to give them any kind of off-axis top-end (ie. anything much above 1000Hz) at all (but your taste and/or style might not need that).

winisd suggests that the LF will give a bit more bass extension than the non-LF.... but in the end, you pays yer money and you takes yer choice - they both seem to be excellent speakers for bass to me (as are the 3012s).

Alan[/quote]

3015 is better than pretty much any other 15 for higher stuff, it is happy in a standalone cab, as I have experienced on the Barefaced tour. Using the LF as a standalone needs a crossover and a mid, because not only is it not great at mids and higher, but it is also kind of uneven (WinISD doesn't really show this, working on data from various people that have tested them) in its upper response, due to not being designed to accurately reproduce them.

[Dood]

Hey Robbie!

I'd save yourself all the hard work and look at Greenboy's Fearful 1515/66 plans and the Fearful threads on TalkBass if you are particularly wanting to build something yourself. The plans, cutting sheets and a wealth of information is available over on the TB wiki. I was surprised at the amount of work that has gone in to designing the perfect cabinet - and I have to say, that if I were in a position to build a cabinet myself - I would definitely go fo this beautiful behemoth!



[url="http://www.talkbass.com/wiki/index.php/Fearful"]http://www.talkbass.com/wiki/index.php/Fearful[/url]

The cutting sheets etc are all available, linked at the bottom of the page, under..err.. the 'links' section!! [url="http://lowdownlowdown.com/greenboy/DL/fEarful/1515+66/"]http://lowdownlowdown.com/greenboy/DL/fEarful/1515+66/[/url]

[RIM Basses]

Cheers for that dood, that cab looks killer. I will take my time with this one and look at a few designs, interesting to get everyones views and all the specs.

Robbie.

[Dood]

[quote name='RIM Basses' post='744275' date='Feb 13 2010, 07:49 PM']Cheers for that dood, that cab looks killer. I will take my time with this one and look at a few designs, interesting to get everyones views and all the specs.

Robbie.[/quote]

Interestingly, the ISP cabs I already use share a lot in common with the design - and indeed Alex's cabs - so I would probably be better off getting a matching extension cabinet for mine - but the 1515/66 would be pretty nice nevertheless.

There was a picture with the grill on somewhere - but I couldn't see it straight away when I posted. {edit - Here is is!}
[url="http://www.talkbass.com/wiki/index.php/Vlad335_1515/66_%22Monster%22"]http://www.talkbass.com/wiki/index.php/Vla...6_%22Monster%22[/url]

[stevie]

My initial reaction was the same as those you've received already in this thread, but I've just modeled this driver and it looks surprisingly good in a 50-litre sealed cabinet. It will handle 200 watts down to low E as long as you don't apply bass boost.

Alternatively, you could use a 70- or 80 litre cab and keep your options open - sealed or reflex. There are a number of advantages to sealed cabs but nowadays these seem to be outweighed by the need to go loud.

I'd be tempted by the 50-litre option myself, but let me know your thoughts and I'll post some cabinet suggestions with graphs for your info.

[stevie]

[quote name='AlanP2008' post='743909' date='Feb 13 2010, 12:40 PM']The Bn15 400x has a stated Xmax of 4mm. That compares very poorly with most of the best (for example) Eminence bass speakers ... The Kappalite 3015 LF has an Xmax of 9.6mm, and an Xlim of 17mm, which is really excellent...[/quote]

Alan, you have to be careful here because there are different ways of measuring xmax (a bit like measuring car fuel consumption). Eminence uses the most optimistic method, whilst Celestion uses the most conservative. The difference can sometimes be as much as 100 percent. The 4mm xmax given by Celestion is probably the equivalent of around 6mm in Eminence spec sheets (my gut feeling). Other speaker manufacturers publish different figures for xmax so that you can do a realistic comparison (see the B&C website, for example) but Celestion and Eminence only publish one figure which is not directly comparable.

[AlanP2008]

[quote name='stevie' post='744704' date='Feb 14 2010, 12:38 PM']Alan, you have to be careful here because there are different ways of measuring xmax (a bit like measuring car fuel consumption). Eminence uses the most optimistic method, whilst Celestion uses the most conservative. The difference can sometimes be as much as 100 percent. The 4mm xmax given by Celestion is probably the equivalent of around 6mm in Eminence spec sheets (my gut feeling). Other speaker manufacturers publish different figures for xmax so that you can do a realistic comparison (see the B&C website, for example) but Celestion and Eminence only publish one figure which is not directly comparable.[/quote]

That is an interesting point.

Is there evidence?

Or is this just a gut feeling? (In which case, perhaps we shoud be measuring your gut!)

Alan

[stevie]

[quote name='AlanP2008' post='744727' date='Feb 14 2010, 01:00 PM']That is an interesting point.

Is there evidence?

Or is this just a gut feeling? (In which case, perhaps we shoud be measuring your gut!)

Alan[/quote]
Well, there's plenty of information available on the different methods of measuring xmax, all of which shows that the method used by Eminence (which is perfectly valid) produces a bigger figure than the one used by Celestion. However, there is no simple formula for converting one to the other. If the manufacturer doesn't supply the information, you have to rely on your gut, I'm afraid. Should you feel like measuring my gut, you're welcome to pop around with your tape measure any time you like.

[AlanP2008]

[quote name='AlanP2008' post='744727' date='Feb 14 2010, 01:00 PM']That is an interesting point.
Is there evidence?
Or is this just a gut feeling? (In which case, perhaps we shoud be measuring your gut!)[/quote]

Ok, sorry - that was far too cheeky!

I was previously pulled up myself for suggesting that Xmax was a bit arbitrary.... It was pointed out to me that the accepted method is the point of 10% distortion (I am assuming that there is a bit more to it than that -- frequency and measuring conditions etc., otherwise it *is* a bit arbitrary). I think it was suggested at the time that there were also older, less standardised methods of producing such a figure - I'm not sure why anyone would wish to stick with such a strategy when it is useless as a means of comparison.

Xlim being the point you can expect permanent damage... Again, there is not too much point a manufacturer being "ambitious" about that (although not publishing a figure at all seems a bit too coy for words...)

It does rather seem that we live in a less-than-ideal world though...

Alan

[RIM Basses]

Buy the way guys im defo uing the celestion bn15-400x drivers so if you fancy helping me with the best cab size and style for them thats great. I can build basses but I dont know where to start with designing cabs, gonna be using the ebs classic 450 when it arrives from the US.

Cheers,

Robbie.

[Mr. Foxen]

[quote name='RIM Basses' post='745211' date='Feb 14 2010, 08:08 PM']Buy the way guys im defo uing the celestion bn15-400x drivers so if you fancy helping me with the best cab size and style for them thats great. I can build basses but I dont know where to start with designing cabs, gonna be using the ebs classic 450 when it arrives from the US.

Cheers,

Robbie.[/quote]

Definitely figure out using WinISD. Trick is to model a cab you know you like, and use if for comparison, because people fuss about the fundamental frequency of notes far too much when just reading numbers. I modelled the GS412 (Eminence Delta 12LFA in 225 litres, tuned to around 40hz from memory) to use as a comparison when figuring a cab for Kappalites.

[RIM Basses]

Just downloaded winisd, Guys I aint gonna be able to work this out. So I going to contact Celestion unless any of you want to work it out for me. Like I said before I will look to build the cabinet 40 x 24 x 17 inches deep, 18mm ply braced inside and looking to use 2-3 four inch ports. I might offset the cones or just have one above the other. If anyone ca work out if this size box would work thats great otherwise I will just gohead and build it when I get time.

Cheers,

Robbie.

[Mr. Foxen]

I just programmed the driver into WinISD, shoot me a PM with an email address and I'll send it to you. It suggests 714 litres for a sealed box giving ideal response. Hmmm. Worked out your box plan is around 170L, which looks reasonable.

The yellow line is a sealed box, looks reasonable, low mid bump bit like the GS cabs. The other line is 2 x 4 by 4 inch inch ports, big peak, gonna bee a bit too much. These are better for sealed. Bear in mind I don't have much clue what I am up to with this, BFM or Claber will probably come and berate me shortly.

[sifi2112]

Hi Robbie,

I've a possible suitable 'sealed & shelved' cab 18mm ply though can't remember what sort ? got wheels for tiltback transport etc .. gonna take speakers out before I move house (or if someone wnats em !)

[url="http://basschat.co.uk/index.php?showtopic=73695&hl=kappa"]http://basschat.co.uk/index.php?showtopic=73695&hl=kappa[/url]

guess it would just require new baffle board .. interested perhaps ?

cheers

Si

[RichardH]

I strongly suspect it will be a verrry heavy beast if made in 18mm birch ply. Even in 12mm birch ply a cab that size is going to be no lightweight.

At a rough guess based on your dims, you'll be using 4096 square inches of ply. I just went and got an offcut of 18mm birch ply out, which weighed 1.2kg for a piece 330mm x 305mm - say it's around 12" square, so 144 square inches. So 4096/144 = 28.

So your cab will weigh approx 28 x 1.2kg = 33kg just for the ply.

Gulp.

Edited February 15, 2010 by RichardH

[RIM Basses]

Thanks for the offer Si, Im gonna try and build my own cab as I want to stain the wood. I dont care about the weight, I know its gonna be a beast.

Cheers,

Robbie.

[stevie]

This almost disappeared off the radar. Here's the model for the 50-litre sealed cab I recommend you try for the Celestion.

Graph 1 shows the response at 1 watt. The blue curve is the Celestion in a 50-litre sealed cab. For comparison, I've included (in green) an Eminence 3015 in a 70-litre reflex cab. There's not really a huge difference between the two. Graph 2 shows how these two cabs compare with a theoretical 400 watts power input. Because it is reflex loaded, the Eminence cab can handle the full 400 watts and will therefore go louder. The Celestion, on the other hand, will only take 200 watts - although adding a second Celestion 15 will make up for the difference.

To improve the power handling of the Celestion, you could reflex load it in a larger cab but this will almost certainly produce a boomy and ill-defined bass sound.

If you have the choice, I'd suggest you use 15mm birch plywood for this, perhaps with an 18mm front baffle.

[RIM Basses]

Cheers for that Steve, Ok so how large is a 50 Litre Cab. Im gonna do the whole cab out of 18mm Marine Birch ply.

Robbie.