I think I made a massive mistake!

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.

JT8

Member
2014-08-09 3:17 pm
About a year and a half ago I decided to build a 6 speaker audio system for a design class assignment...Obviously, a bit of time has pasted since then and it is still in a pile of pieces because I believe I have made a huge mistake.

I can barely remember anything I learnt back then from doing the project, but what I have now is a bunch of amps, crossovers, and drivers which I don't think go together at all.Here is what I have.

Drivers:
2x SB Acoustics :: SB26STCN-C000-4

2x SB Acoustics :: 5" SB15NRXC30-8

2x SB Acoustics :: 10" SB29NRX75-6

Amps
2x CxD200-8R Connexelectronic
2x IRS2092 Kit Connexelectronic
1x SainSmart LM3886TF Amplifier AMP+Power Supply Rectifier Filter Completed AUDIO Board Kit 3D Printing, Arduino, Robotics | Sainsmart

Power supplies for amps
1x SMPS500R Connexelectronic
1x SMPS500QR Connexelectronic

Crossover:
2x https://www.minidsp.com/products/minidspkits/2-x-in-4-x-out

Please by all means tell me how much of an idiot I am for trying to build such a complicated speaker system, but what I need right now is a lot of help to try and resurrect this project and not waste a lot of money.

I need to know if the amps are even usable with the drivers, and if not, how to amend this issue. I know there is a lot of smart people on here with big hearts that can help me out, thus why I come to you in this dark dark hour.
 

Clashing

Member
2014-02-05 6:39 pm
Ok,
first you've got some very nice value drivers. Now, just eyeing what you have to work with it, I'd suggest that you cross the tweeters around 1.5k on a 12 db slope (second order, calculators are online), the midrange on an 18 db or 24 db also at 1.5k to match the tweeter. Cross the woofers at 150 hertz on also on a 12 db slope and I would say, and this preference but I believe that it favors ultimate quality over SPL, allow the midrange to roll off into the bass on a 12 db slope. You will also want a baffle step correction circuit which can be calculated online. The woofers enclosure ought to ported, just eyeing the Thiele Small Parameters. On a cabinet material, Baltic Birch is considered one of the best cabinet materials, but plain old MDF work well too. Baffle width ought to be narrow in my opinion as I hear speakers to sound better with narrow baffles. Also make sure both the cabinet and baffle are well braced. I don't have modeling software, but think about an enclosure about three feet tall with the midrange on top the tweeter in between and the woofer on bottom. Front ported is better for bass in my opinion, again just an opinion. 1/2 inch MDF makes a good cabinet material as you seem to on a budget. On the looks, you could go straight industrial with the cabinet finished in polyurethane and screws exposed, even using screws along with glue to fix braces inside the cabinet. While Im thinking about it, you could use a mini DSP for a crossover. That is pretty much the conceptual ultimate as you implement almost any crossover slope and phase possible. However you need six total channels of amplification. If not feasible, then no active crossovers. That means your best bet is to create a small airtight compartment in the bass of the speaker where you lay out the crossover components or Madisound can build you one for a price and your just left with the cabinet work.
Hope this helps...
 

eriksquires

Member
2013-05-10 4:11 pm

Those drivers all suck. Send them to me and I'll save you the trouble of recycling them...... :D

It's all fine, but it IS a little complicated for a school project. I mean, if you can get away with a 2 way and a passive crossover for a grade it may not be a bad idea to rethink it now that the endorphin driven spending high you had when you bought them has passed.

Otherwise I'm sure you'll make something great with what you have.

Best,


Erik
 

wintermute

Just another Moderator
Paid Member
2003-08-03 11:43 am
Sydney
Don't worry. Be happy :)

It may seem a bit daunting on how to start, but what you have does not seem like a mismatch to me. I think you will be able to put together a pretty decent system with those components.

Start out by getting the enclosure for the woofer and mid right. The woofer looks like it would be best in a vented enclosure. The mid should be sealed. Get a box modeling program (I prefer unibox, which is excell based) but there are plenty of alternatives.

The mid is really a bit of a no brainer, a sealed box with q of 0.707 should work well. Once you see how that performs (in the sim) it will give you an idea for your lower crossover point.

I assume you intend to use the LM3886 on the tweeter (more than enough power) and the two other amps for the woofer and mid (again more than enough power).

The great thing about the minidsp (not that I've ever done any dsp based crossovers) is that you will be able to just experiment, you don't need to worry about time alignment etc as it can be handled in the DSP.

Get the boxes right and you are half way there. Then you can experiment with the minidsp and see what does and doesn't work well.

Tony.
 
That's all great stuff and you can make some excellent speakers with them. The amps and power supplies are all excellent. Relax and sit back and read up. With miniDSP you will be fine. Maybe even try some cool transient perfect XO topologies.

Get PCD or Xsim. Get a mic. Get REW.

Away you go - you are quite lucky to have such nice stuff to start out.
 

JT8

Member
2014-08-09 3:17 pm
Thanks for the reassurance everyone! I'm just terrified of blowing up the drivers, but I've done some more reading and from what I understand, a speaker protection circuit should prevent them from getting wrecked. I'll have to go read up on what you guys are saying, because coming from a health science background....I have no idea what you are saying haha. Now I have something to do for the final weeks of my uni break
 
A plan helps :)

Cartoon that even pre-dates the Internet :)

It is possible that I built a subwoofer that was too big to move out of the room :(
 

Attachments

  • canoe.jpg
    canoe.jpg
    16.2 KB · Views: 310

eriksquires

Member
2013-05-10 4:11 pm
Thanks for the reassurance everyone! I'm just terrified of blowing up the drivers, but I've done some more reading and from what I understand, a speaker protection circuit should prevent them from getting wrecked. I'll have to go read up on what you guys are saying, because coming from a health science background....I have no idea what you are saying haha. Now I have something to do for the final weeks of my uni break

Um, you just keep making it more complicated and delaying how soon you'll have something to listen to. Don't get me wrong, speaker protection circuits are a good thing, but dude, get started wiht the basic design already instead of constantly adding wishful features to the list. :)

Make something now! :)

What exactly are your fears? If you are worried about the tweeters, put one or two 10uF caps in front of them to ensure you don't pass a lot of bass or have turn on transients that send the dome's flying. Done.

Best,


Erik
 

JT8

Member
2014-08-09 3:17 pm
Um, you just keep making it more complicated and delaying how soon you'll have something to listen to. Don't get me wrong, speaker protection circuits are a good thing, but dude, get started wiht the basic design already instead of constantly adding wishful features to the list. :)

Make something now! :)

What exactly are your fears? If you are worried about the tweeters, put one or two 10uF caps in front of them to ensure you don't pass a lot of bass or have turn on transients that send the dome's flying. Done.

Best,


Erik

You're right, I really should stop stalling. All the housings and everything have been made, I just stopped at the amps out of fear of screwing everything up. I'm going to try and finish it by weeks end :D. One more question. I'm not sure which terminals on the amp amps connect to the speakers. They are labeled Out, GND, V-,GND, and V+. I also have the Mute, GND, and Input terminals too.
 
JT8,
I use two of those three in my three way actives; my tweeter is a Vifa XT25 instead. I'm happy with them.

I use LM3886 chipamps for all drivers and an ESP 24dB analog crossover. I am "in the process" of converting to 2x4 MiniDSPs for the crossovers.

I'm happy to help if you need it. I'm in Melbourne.
 

JT8

Member
2014-08-09 3:17 pm
It would be awesome if you could help me out Tromperie! I'm almost finished now, I just need to wire them up, adjust the crossovers, and play some beats. I am having issues with the wiring as I don't understand what a few of the symbols means. I have a attached a wiring diagram so you can see what I am dealing with. The orange lines are what I have already wired up. Also, the transformer I am using for the LM3886 system has dual secondaries and I'm not sure if both need to be connected to the one power supply unit for the LM3886 system.
An externally hosted image should be here but it was not working when we last tested it.
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.