Jump to content
Sign in to follow this  
burdizzos

[FAQ]Speaker building

Recommended Posts

The Burdizzos Mod

 

 

This mod was originally done on an Avatar B212. I swapped out the horn for a Galaxy Audio 5" driver. I have since used Galaxy's new Neo 5" driver and I think it sounds better than the standard driver. It has a claimed range of 150 to 18,000Hz and a claimed power handling of 100 watts RMS. If a crossover set at 500 Hz is used, it fills out the high frequency sound of the bass without being harsh, as horns often are.

 

trickedoutavatar.jpg

 

This can be done in any cab where there is room on the front baffle to fit the new speaker. It has a 4.75

Share this post


Link to post
Share on other sites

Here's a little spiel I wrote in another thread regarding the Avatar horn modification. It could be applied to speaker building (mostly crossover use) in general as well:

 

The 'Avatar horn mod' many people speak of is simply adding an appropriate high pass filter to the horn. The "crossover" that comes stock with the Avatar cabs is simply a capacitor wired inline with the foster horn, providing a 6db per octave rolloff below the crossover point (which is 3500hz if I remember correctly). Simply stated, this slope isn't steep enough to give proper protection to the horn, resulting in 'harshness' as the horn tries to produce frequencies that are at (and below) it's lower limits. With the simple capacitor acting as the HPF, the horn is only down 6db at 1725hz and is still getting a fair amount of power.

 

In order to get better performance, reliability, and sound from the horn, a better HPF with a steeper slope is needed. I think something along the lines of a 3rd order (18db/oct) or 4th order (24db/oct) would suffice. If you do a search on talkbass.com you'll see that a lot of folks there have made their own linkwitz-reilly 24db/oct high pass filters for their Avatar cabs and significantly improved the performance. In fact many even lowered the crossover point to 3000hz with good results - you can do this because with such a steep rolloff you're still going to have much, much less power going to the horn at 1725hz with a 3000hz 4th order than you would with a 3500hz 1st order.

 

If you're not up to building your own high pass filter, I'd suggest installing this one from Eminence:

http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=290-602

 

It's a 18/db per octave HPF with built-in bulb protection. Replacing the existing cap with this crossover with definitely improve the horn's performance and reduce harshness.

Share this post


Link to post
Share on other sites

This little page rules all when you need to design your own crossover. You plug in the impedance if your drivers, the frequencies you want and the type of crossover, and it'll give you a little diagram with the values for the components included.

 

http://www.lalena.com/audio/calculator/xover/

Share this post


Link to post
Share on other sites

Actually, Dave is now putting real 12 dB slope crossovers in his cabs.

 

newinput2.jpg

 

 

Good on him, he made a great cab better and didn't jack up the prices.

Share this post


Link to post
Share on other sites

A few questions:

 

1. Where can I download winISP?

2. Would it be possible to convert an Avatar 115 into a 118? It looks like there's room in the enclosure to where I could just make the hole bigger.

 

b115h%20kappa.jpg

Share this post


Link to post
Share on other sites

WinISD

 

To download WinISD,

click here.

 

 

There are a couple of important things to know about WinISD.

 

First, the database that comes with it isn't accurate. You will need to upload specs to get the best results.

 

Second, ISD is not perfect. It is a free program that, in my experience, performs almost as well as box building programs that you have to pay for. In the speaker cab building game, approximations are almost always close enough.

 

The Help menu is very good, but I

Share this post


Link to post
Share on other sites

That implies that the port is far too short and you haven't entered a vallid value for the port diameter or size.

 

When the Vent Match number is red, I think it is telling you that the port is too small and could result in port noise.

 

The bigger the port, the better, in my opinion.

Share this post


Link to post
Share on other sites

Hey burdizzos, where would I find the Pe and Z on Eminence's site? Also, which SPL do you go with on their sensitivity charts? Thanks.

Share this post


Link to post
Share on other sites

Originally posted by burdizzos

That implies that the port is far too short and you haven't entered a vallid value for the port diameter or size.


When the Vent Match number is red, I think it is telling you that the port is too small and could result in port noise.


The bigger the port, the better, in my opinion.

 

The problem I have is, there are times where I can't get it to NOT be red. I can tinker with all kinds of numbers and it doesn't change...

C7

Share this post


Link to post
Share on other sites

Originally posted by burdizzos

Actually, Dave is now putting real 12 dB slope crossovers in his cabs.

 

Yeah, I saw that recently. Very good on him. It's still not as good as a third or fourth order in my opinion (at least on a compression horn), but definitely a step above the first order he was using.

Share this post


Link to post
Share on other sites

Anyone know where I can get 2x15 or 4x12 sidewinders for bass/guitar cabs? I have a 79' Marshall bass 2x15 I'd like to put in there and a 2x12 fender cab I'd like to put in there for guitar.

Share this post


Link to post
Share on other sites

Originally posted by bpocall

Hey burdizzos, where would I find the Pe and Z on Eminence's site? Also, which SPL do you go with on their sensitivity charts? Thanks.

 

Pe is the RMS Power rating, in watts, of a speaker.

 

Z is the rated impedance, for most eminence drivers, it is 8 ohms.

 

Sensitivity is a tricky thing. Ideally, you'd like to get the speaker's sensitivity at or below 100 Hz, but that information usually isn't available. So, you just have to go with what you're given and consider the source as a means to remain objective when comparing drivers.

 

When it comes to Eminence, I'd recommend using the sensitivity at the lowest frequency available, which is 200 Hz. You could also print out the response graph for the speaker and use a ruler to determine the sensitivity at 100 Hz.

 

Always look at a response graphs if they are available. This will give you a better idea of how the speaker will work in the 40 Hz and below area. If a speaker is 97 dB at 1000Hz, but only 89 at 100 Hz, you might want to look elsewhere.

Share this post


Link to post
Share on other sites

There is, slightly, more gluing surface and additional strength with dado joints, but they have to be cut cleanly or the gluing surface is diminished. The dado joint traps the wood in place. This joint is useful when isolating one speaker from another, in the same box.

Share this post


Link to post
Share on other sites

Neodymiun Discussion

 

In another thread we were discussing the differences between an Avatar B212 loaded with Delta LFs and one loaded with Deltalite 12s.

 

Originally posted by bassman1956

Here's stats as they're posted on the Parts Express page, for a 12" Delta LF and a 12" Deltalite. From these, aside from the very obvious weight differences, it's looks to me like the neos would even be better on the low ends. But it seems you're saying that's not so. Care to expound?



EMINENCE DELTALITE 2512 12" NEODYMIUM DRIVER


Magnet weight: 7 oz.

Shipping Weight: 8lb. 6 oz.

Resonance:42Hz

Usable Frequency Range: 30Hz - 3.5kHz

Sensitivity @200Hz: 97 dB



EMINENCE DELTA-12LFA 12" LOW FREQUENCY DRIVER


Magnet weight: 56 oz.

Shipping Weight: 13lb. 6 oz.

Fs: 45 Hz

Frequency range: 45-3,000 Hz

Sensitivity @200Hz: 94.5 dB

 

 

To which I replied:

 

Those specs don't even tell half of the story.

 

The most important part about how a speaker sounds is the cabinet that is used.

 

Since we are talking about an Avatar B212 cab that is roughly 5 cubic feet and is tuned to 50 Hz. In that cab the speaker with the lower Vas will work better.

 

Delta 12 LF Vas: 2.4 cu. ft.

 

Deltalite 2512 Vas: 5.46 cu. ft.

 

If you put a single Deltalite 12 in the B212 sized cab, it will have a similar response to the same cab loaded with two 12 LFs. It will also be just as loud since the Deltalites are 3 dB more efficient than the LFs. However, it won't handle as much power and it won't move as much air, so at 50 paces and 500 watts, the 2x12 LF configuration will be louder.

 

My 1x12 Neo cab is 3.7 cubic feet and my 2x12 Delta LF cab is about 8 cubic feet. At close range, they are almost equally loud, but at the other side of a 400 sq ft room, there is an audible difference. Teh big difference is that the LF cab is the right size for those drivers, it plays flat to 40 Hz and plays the B string with authority. The Deltalite is in too small of a cab, so it's low end response isn't nearly as good.

 

 

The Avatar B212 is way too small for two Deltalite 2512s, but I think Dave got some kind of special brew neo speakers for his cabs that I think have a higher Xmax, but based on his description of the the difference in sound, I'd say that they are very similar to standard 2512s in sound.

 

 

 

 

The bottom line:

 

The Delta 12 LFs will play lower and handle more power in an Avatar B212. It will also be 10 pound heavier and probably take more abuse.

 

The Neo B212 will be 3 dB more efficient and have a fantastic upper mid response which yields a better tone and a less forgiving cab(your mistakes will be more apparent). The tradeoff is a loss of low end. If you play a 5 string, the low B will lack authority whith this cab and the EQ will only be able to do so much given the power handling of the Neo speakers.

 

 

 

Here's another difference that may or may not be worth anything, but it is interesting.

 

The temperature thing that is discussed about Neodymium is the Curie Point.

 

The Curie point, or Curie temperature of a ferromagnetic material, is the temperature above which it loses its characteristic ferromagnetic ability to possess a net (spontaneous) magnetization in the absence of an external magnetic field. - Borrowed from Wikipedia

 

The Curie point of Ferrite is 450

Share this post


Link to post
Share on other sites

Originally posted by burdizzos

Let's talk construction.



Where are the woodworking folks who can explain why a dado is better than a butt joint?

 

It's a heck of a lot easier to square a dado joint than a butt joint. Also there's more exposed wood allowing a more secure glue joint. Dovetails are ideal IMO but I don't have a dovetail jig.

Share this post


Link to post
Share on other sites

Originally posted by Emprov



It's a heck of a lot easier to square a dado joint than a butt joint. Also there's more exposed wood allowing a more secure glue joint. Dovetails are ideal IMO but I don't have a dovetail jig.

Dovetails aren't a good choice for plywood. Solid wood, yes. Plywood feathers and delaminates sometimes.

Share this post


Link to post
Share on other sites

Originally posted by Gruven


Dovetails aren't a good choice for plywood. Solid wood, yes. Plywood feathers and delaminates sometimes.

 

With higher grade plys I've never had a problem with them. I'd never do it on cheaper stuff but, if we're talking voidless birch, I'd do it every time if I had the jig.

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Sign in to follow this  

×
×
  • Create New...