Thoughts on the Eminence Legend BP122

[BadExample]

@ThisBass Have you ever compaired the wisISD or eminance to a third program, like @fdeck 's on-line program?

I didn't know winISD did port calculations other than mach (airflow speed for preventing whistling problems). I think its very common to use other software for port tuning, but certainly a good idea to bring it up.

@pie_man_25 +1, these are very cool low cost drivers!

 

[pie_man_25]

@pie_man_25 +1, these are very cool low cost drivers!

They're definitely good, and not too expensive, but he could save himself a few bucks using the 15" that he already has. Sure, it's a bigger footprint, but saving a hundred and ten plus shipping (which is what it'd cost for me, at least), is a much smaller footprint in your wallet.

 

[ThisBass]

@ThisBass Have you ever compaired the wisISD or eminance to a third program, like @fdeck 's on-line program?

It's some time ago a German bass cab builder told me that WinISD is faulty on the calculation of vent length.
Actually it was Hans of FMC-Audio. I asked him the question for fine vent length cause I was dubious about the WinISD calculated vent length.

The Eminence designer is basically the same application like bassBox-pro both published by Harris Tech Audio
HT Audio home page
BassBox-pro is not for free but worth every $cent. The driver data base is giant therefore makes "on the fly" comparisons of different drivers very easy to use.

cab: 3.5 cu ft
tuning: 50Hz
no of vents: 2
vent diameter: 4"
shape: round

WinISD-pro

BassBox-pro

The deviation of WinISD versus BassBox-pro calculates to a plus in vent length of 45%

BassBox-pro calculated (actual) cab tuning based on WinISD-pro calculated vent dimensions:
45.9 Hz

 

[BadExample]

Interesting... if I ever build ported cabs, I might just buy it.

 

[tewnty_two]

So This is where I'm at now:
As @pie_man_25 stated the best bang for buck at this point will be to use the CB158 in a small box. I can get a piece of 4x4 1/2 ply at the local lumbershop for $16 and that will be enough to build a small cab.

Here's the WinISD data:
BP122 sealed f3 @ 70HZ in 0.87 cu.ft (white)
CB158 sealed f3 @ 82Hz in 1.7cu.ft (yellow)
CB158 vented tuned to 51Hz f3 @ 74Hz in 1.7 cu.ft (blue)

Compare

• tewnty_two
• Oct 26, 2016

Dimensions for the CB158 box are:
Interior 16.5 x 10.5 x 17"
Exterior 17 x 12.25 x 18"
that's with a .75" recessed front baffle

First I'll give the cab a spin sealed and see how I like it. If it sounds like crap I'll add 2 3x5" round ports and vent the mofo!
The vented build is straight from Eminences "recommend enclosures" and verified by WinISD and using BoxSim for the port calculations. (thanks @ThisBass for the tip)

Boxsim ports for CB158

• tewnty_two
• Oct 26, 2016

Boxsim ports for CB158 port calulations

FYI there's a free program called Link Removed that will generate a cutlist for you just by entering your needed dimensions and source dimensions.

cutlist

• tewnty_two
• Oct 26, 2016

If all this ends up not meeting my project goals then I can go the BP122 route and only be out minimal $$.
Or just build the BP122 at a later date to see what it sounds like. A sealed 2x12 does sound sweet.....

 

[pie_man_25]

Seems like you know enough of what you're doing, good luck man!

 

[tewnty_two]

Seems like you know enough of what you're doing, good luck man!

Do I need to worry about bracing in a cab this size ?

 

[pie_man_25]

Do I need to worry about bracing in a cab this size ?

Yes, but it's really not that difficult. I'm honestly not an expert on this stuff, I've just been doing it for a couple years. That said, you could just run some 1/2" or 3/4" stock across the panels from edge to edge. Make sure they're perpendicular, and maybe space them 6"-8" apart or so. You could also take some stock or some dowels and run them from the centre of each panel to the center of the one across from it - by flexing the panels it helps to reduce or eliminate panel vibration. With this said, I'm really no pro, you could probably search this stuff or maybe look it up on google and get some good results.

 

[tewnty_two]

You may not be a pro but you definitely helped me out a ton, and for that I thank you.

 

[pie_man_25]

You may not be a pro but you definitely helped me out a ton, and for that I thank you.

Thanks man, I'm also definitely checking out Cutlist.

 

[BadExample]

Do I need to worry about bracing in a cab this size ?

Mine is close to 4 cu ft, 3/4 ply, heavy as hell which I don't care about, no bracing except the assembly cleats which don't do much. With half inch ply you probably want bracing front to back, then side to side if it's very deep. I'm not quite sure which part is which. If weight doesn't matter, brace it up anyway.

PL glue is forever, just like diamonds, herpes and x-wives. Like pie_man said, they tend to want to bow in and out under pressure which alters your design. It seems the pressure would be more front-rear in the direction the cone moves, but I'm not so sure it doesn't equalize. Some people on unbraced cabs use a double layer of wood on the baffle, and sometimes on the back. If you PL braces front to back, I wouldn't plan on getting that front baffle off for a 12 or different size 15.

You also want to make sure whatever handles, dish or anything that is recessed into the wood is sealed if the hole breaks through, and if not you want to fil the void with something. PL works, so does RTV. I cut mine through so there was no voids, filled about flush to the wood inside. I offset my woofer about an inch to one side. Some people think it's important, most don't. I don't think it can hurt and it makes people wonder why it looks a little off Bunches of other tips if you read some DIY threads, DIY/ohms sticky and google. PArts express has a speaker bible.

Oh here's one, I forgot to put the speakons in the disk before mounting it and PLing it. Egads, PITA through a 15 in hole! Mount and put the speaker wire in first!

 

[tewnty_two]

Mine is close to 4 cu ft, 3/4 ply, heavy as hell which I don't care about, no bracing except the assembly cleats which don't do much. With half inch ply you probably want bracing front to back, then side to side if it's very deep. I'm not quite sure which part is which. If weight doesn't matter, brace it up anyway.

PL glue is forever, just like diamonds, herpes and x-wives. Like pie_man said, they tend to want to bow in and out under pressure which alters your design. It seems the pressure would be more front-rear in the direction the cone moves, but I'm not so sure it doesn't equalize. Some people on unbraced cabs use a double layer of wood on the baffle, and sometimes on the back. If you PL braces front to back, I wouldn't plan on getting that front baffle off for a 12 or different size 15.

You also want to make sure whatever handles, dish or anything that is recessed into the wood is sealed if the hole breaks through, and if not you want to fil the void with something. PL works, so does RTV. I cut mine through so there was no voids, filled about flush to the wood inside. I offset my woofer about an inch to one side. Some people think it's important, most don't. I don't think it can hurt and it makes people wonder why it looks a little off Bunches of other tips if you read some DIY threads, DIY/ohms sticky and google. PArts express has a speaker bible.

Oh here's one, I forgot to put the speakons in the disk before mounting it and PLing it. Egads, PITA through a 15 in hole! Mount and put the speaker wire in first!

Sweet.
That's the stuff I need to know, all the details.
I got one more for you, it's says minimal fill. When's the best time to apply?

 

[pie_man_25]

Sweet.
That's the stuff I need to know, all the details.
I got one more for you, it's says minimal fill. When's the best time to apply?

Cabinet filling is kind of like salt AFAIK, you do it "to taste" after the whole thing is made and functional. Well, okay, salt is more complex than that, but honestly with speakers it's about that. Too much and you'll take out low-end energy, too little and there won't be enough to reduce standing waves. If you get it all just right, you'll probably know it.

 

[Rick James]

Thanks for the info!
So I gather that the BP12 will fill my needs but the 15 will give better performance.
If I had to buy a driver I would prefer the BP122 for the smaller footprint.
However, I have an Eminence CB158 that is currently in the top chamber of a old Peavy 215 cab. What are your thoughts on using that driver in a small sealed box around 1.62 cu.ft?
The first priority was having a small footprint, thats why I was looking at the BP122 but if the CB15 will work in a small enclosure then I can work with that!
Here is a plot of the BP112 (blue) in 0.875 cu.ft. and the CB158(yellow) in 1.629 cu.ft

Small Sealed Cab Design

• tewnty_two
• Oct 25, 2016
• cab sim

Blue is Eminence BP122
Yellow is Eminence CB158

EDIT:
I threw the specs in for a small vented cab @ 1.7cuft. tuned to 51hz with 2 round ports 7.5" deep from the suggested builds on the eminence website.

cabBuild

• tewnty_two
• Oct 25, 2016
• cab sim

Added the CB15 in a small vented cab

You're giving up a lot of low end with small cabs. This shows the BP122 in the BFM Simplexx 12, sealed and ported. The overall size is 2.2 cu ft. The footprint is 14.5 x 20 inches.

 

[BadExample]

I got one more for you, it's says minimal fill. When's the best time to apply?

For sealed, I stuff loose polyfill or something through the cutout in the baffle. Usually get a listen first, pull the speaker and stuff, listen again and adjust.

Rick, check the small sealed Invalid Link Removed smaller foot print than the Simplexx 12.

b =
2 cu.ft
V(total) =
2.108 cu.ft
Qtc =
0.885
QL =
20
F3 =
56.95 Hz
Fill =
normal

F3 looks better.

He wants smaller as his #1 priority. IDK if that includes height, there might be WAF involved, then it probably does. Small room usually = lower volumes usually = more eq before xmax. Smaller sealed boxes handle LF eq well as long as there is not a thermal problem.

 

[ThisBass]

QL affects F3.
Bigger going number for QL means lower going number for F3.

Eminence sets QL = 20 for sealed cabs while for ported cabs QL=7

WiniISD default QL = 10 for both sealed and ported
See box editing window, bottom line "properties" to edit QL on WinISD

 

[space pulse]

I am considering using the BP122 in a ported Ampeg SVT 212E. Wondering if this speaker is good in a medium-sized ported cab? I don't have measuring tape at the moment. Look below to see what the cab looks like under the grill. Mine is much dirtier and the cones are blown. Seems like it'd be easy to just drop these in.

However, I was also considering rewiring the cab such that it has two 4Ohm speakers wired in series to make it easier to pair with my other 8Ohm cabinet (Powerhouse 212 with tweeter) and thus be a little safer for my Mesa Walkabout Head. If I use the Legend speakers, I'd be running the Walkabout with a 2.6667Ohm load and risk overheating. I hear good things about the Eminence Deltas in bass cabinets, and they are available in 4ohm, but I am worried about losing out on that 2-3KHz range. Any advice?

 

[Nephilymbass]

I was looking at the new BP112 and wanted to see what the speaker gurus here have to think of putting this into a small box as per their .pdf.

Specs:
Power handling: 250 watts RMS/500 watts max
• VCdia: 2"
• Le: 0.84 mH
• Impedance: 8 ohms
• Re: 5.66 ohms
• Frequency response: 35 to 2,300 Hz
• Fs: 35 Hz
• SPL: 94.1 dB 1W/1m
• Vas: 5.56 cu. ft.
• Qms: 9.26
• Qes: 0.57
• Qts: 0.54
• Xmax: 6.2 mm

Would vented (2.55 cu.ft.) or sealed (0.875 cu.ft.) be better?
How would it compare to say the Beta 12a or the S2012?
The cab would be used for at home practice and possibly for blues/R&B with a drummer and 1 guitar.
I have a 1x15 cab I could stack it on if I needed for volume or bottom end for jamming out in the garage.

I haven't tried that exact speaker but I love the bp102 200w tens so it's a speaker I'd consider if I went with 12s. I put the tens in a sealed cab.

 

[BogeyBass]

For a ported cabinet like the ampeg 212 just use the Eminence Beta12a2
the bp lacks in highend and sensitivity at 94dB
The beta 12a2 has higher sensitivity at 98db and is similar if not the same as the factory 38 ounce magnet
eminence factory speaker.
Likewise no you dont want series speakers or a 2ohm load.
a pair of 8ohm Beta 12a2 both in parallel will produce a proper and safe 4ohm load for your amplifier.
likewise if you would like a 8ohm 212 you would need a pair of 16ohm speakers
and i would contact eminence since the beta 12a2 is available in europe as 4,8 and 16 ohm voice coils so it should be possible to special order a pair at 16 ohms which would give you a 8ohm cab.

Speaker Detail | Eminence Speaker

 

[space pulse]

For a ported cabinet like the ampeg 212 just use the Eminence Beta12a2
the bp lacks in highend and sensitivity at 94dB
The beta 12a2 has higher sensitivity at 98db and is similar if not the same as the factory 38 ounce magnet
eminence factory speaker.
Likewise no you dont want series speakers or a 2ohm load.
a pair of 8ohm Beta 12a2 both in parallel will produce a proper and safe 4ohm load for your amplifier.
likewise if you would like a 8ohm 212 you would need a pair of 16ohm speakers
and i would contact eminence since the beta 12a2 is available in europe as 4,8 and 16 ohm voice coils so it should be possible to special order a pair at 16 ohms which would give you a 8ohm cab.

Speaker Detail | Eminence Speaker

This is incredibly helpful. I'll probably just just get the 8ohm speakers and find a way to bi-amp if I want to use 2 cabs or start looking into trading my head for something that can handle 20hms safely if I really want to be lugging cabinets everywhere. I think I could just borrow my roomie's head because this is mainly for messing around at home. I wouldn't want to gig both cabs. I can barely fit one in my Corolla as it is. Mesa's manual says that you won't fry the amp at 2Ohms, just that the power section will shut down if the extra load causes any heat issues. Might be fun to just mess around with once in a while at home.