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Building 212 cab

SimonD

SimonD

Oct 27, 2021
36
41
#1
Hi guys,
I need to replace my Ampeg PF-210 and PF-115...
I plan to build a cab 212 with Eminence 3012HO speakers.
I made myself a box design with WinISD. (115 liters, 60 hz, max air velocity 23 m/s and which respects my Xmax limit of 6.2mm).

I will try without tweeter, because it is the simplest and most economical solution.
I was wondering if I should still put a filter (highpass?) to protect the speakers ?
If so, it should support the 800 watts of the speakers?

And if I ever decide to install a twetter, can I put an 8 ohm one in parallel with the two 8 ohm speakers (total of 4 ohms) or the speakers must be seen as a total 4 ohm load and i must have a 4 ohm tweeter?

lots of questions..I known!
Thanks!
 
#2
Use an active HPF in the signal path BEFORE the amplifier stage. It can be before the input to the preamp or inserted in the effects loop if there is one. This puts it in the signal path between the amp's preamp and amplifier stages.

You'll need a passive crossover or a passive HPF between the amplifier output and the tweeter or HF driver if you decide to add one. This will effectively isolate the driver and you won't need to worry about the change in the impedance of the circuit to the LF drivers. Something like this is typical: [Invalid or Expired Link Removed]

The link is for a 1600 Hz HPF, but other frequencies are available. You need to choose the crossover frequency based on what sort of device you use for a HF driver -- the device manufacturer will typically recommend a crossover point, or you can extrapolate it from the HF unit's frequency response graph.
 
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#3
Can I use a crossover board and connect only the tweeter? I'm presuming that if I connect the speakers, I need a 800W power handling crossover board? OR I connect only one of the two speakers?

Thanks again! :)
 
#4
A high pass filter (HPF) is the high frequency half of a crossover. With a full range driver like the KL3012HO in a bass cab, you only need a HPF for the tweeter as mentionned in Post #2. Run the 12" drivers full range. A 400 watt HPF for an 8 ohm tweeter will be fine for a 4 ohm 800 watt 212 cab. With the KL3012HO drivers you could use an Eminence 3.5kHz HPF. Here is a link from Parts Express:
Home
The power band, which is where impedance matters most, is under 1.6kHz and will be set by the 2 woofers in parallel. A tweeter high passed at 3.5kHz won't effect the cab impedance seen by the amp since there isn't much power at those upper frequencies.
Also, WinISD overestimates port length by about 40%. If you make the ports according to WinISD your cab will end up tuned lower than design.
 
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#8
#9
SimonD said:
I want a really good 212 bass cab...:)
I go with the HO version cause I don`t want too much low end...like LF model seems to be..
which speakers could be better?

Thanks
Click to expand...

I'd suggest you start here ;)
knob-on-bass-amp-low-frequencies.jpg
 
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#10
I read a lot on the forum and several people seem to say that with the "LF" model we need a midrange speaker because they lack mids that a tweeter can't reach (below 2kHz).
It`s my first construction, I want to stay with a 2 ways cab...but..
Is 2 speakers 3012 LF could me a better choice instead of the 3012 HO models? :nailbiting::nailbiting::help::nailbiting::nailbiting:
 
#12
+1 ^^^ There are several robust full range 12" drivers suitable for a 212 bass cab. The 3012HO is certainly a good candidate but IME is more suited for 4-string bass and not as much for the extended low end of a 5 or 6 string. Eminence, Faital, and Beyma all have suitable drivers but you need a better idea of what you're looking for. What's your budget, size and weight constraints, power handling/max volume, type of voicing, etc.

The Beyma 12WR400 is a 400 watt driver which makes a fine bass cab and goes lower than the 3012HO but weighs more (12.1 vs 7.1 lbs) due to its ferrite magnet. That would be my choice for a 212 if you don't mind a cab weight of about 65 lbs. You can even buy a Chris Cole kit from Speakerhardware.com It's a proven design that just needs to be assembled and finished. I'd load it with the Beyma 12WR400 instead of the Eminence Deltalite 2512.
Chris Cole 1212 Bass Guitar Cabinet Kit

Lots of potential choices.
Here is a site with a good selection of drivers.
https://usspeaker.com/homepage.htm

Here is a link to loudspeakerdatabase which is a great screening tool if you know how to narrow down the suitable T/S parameters.
Loudspeaker Database

You might also just check the TB classifieds for used 212 cabs around your area. There are always good deals to be found but nobody wants to ship - too expensive.
 
#13
Yes, for me the weight of the cab is really important. I have to go down stairs à each pratice with one of my band.
So I need Neo magnet. Also, my amp is a GK 1001RB II, (700w @ 4 ohms), so I need a minimum RMS power of 300 - 350 watts..
 
#14
Here's a cab I had LDS build for me some years ago. This cab is loaded with Eminence Kappalite 3012HO drivers and an 18Sound horn. I play 4 string and had no problem being heard in a loud mix. I did, however find it a little awkward to move by myself, and subsequent back problems forced me to move it on. Fellow member, Groovaholic now owns it and I believe is still using it.
GK+LDS Rig.jpg
 
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#15
Nice Cab! Did you have enought of low end with these speakers? Of course I play with a 5strings...
The box I want the build is smaller than this...I want something comparable to Mesa 212 vertical, GK 212 NEO IV or Berg NXT212...Something like 19" wide and 28-30" height....easy to carry...
 
#16
SimonD said:
Nice Cab! Did you have enought of low end with these speakers? Of course I play with a 5strings...
The box I want the build is smaller than this...I want something comparable to Mesa 212 vertical, GK 212 NEO IV or Berg NXT212...Something like 19" wide and 28-30" height....easy to carry...
Click to expand...
As I said, I play 4 string, so I can't comment on 5 string compatibility. I'm not a deep bass player, I go for more of a low mid sound. Try sending a pm to Groovaholic for his comments. Last I heard from him, he was still using it. As far as size goes, I believe Don at LDS figured out the dimensions for what I wanted, namely everything vertical. If you don't want the horn, could be done somewhat smaller.
 
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#17
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#18
SimonD said:
Nice Cab! Did you have enought of low end with these speakers? Of course I play with a 5strings...
The box I want the build is smaller than this...I want something comparable to Mesa 212 vertical, GK 212 NEO IV or Berg NXT212...Something like 19" wide and 28-30" height....easy to carry...
Click to expand...
How much are you willing to spend on this project?
 
#20
Yeah, At first, I wanted to buil these Fearful desing ..but It's hard to me to buy all the parts required for this bulding without having custums fees ...(I'm in Canada). Also, I found these a little bit to big for me...I want something more easy to carrying. Following this, I decided to simplify my desing and use only 2 x 12" speaker and a tweeter...
 
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