Loudspeaker Electronics

morfius

Member
2007-09-08 1:43 pm
I am going to build a relatively simple speaker and have found two components in particular which I need to ask some questions about.

1 - 300mm (12”) 300W Bass Speaker

http://www.maplin.co.uk/module.aspx?ITAG=SPEC&ModuleNo=21379&doy=17m12#spec

2 - Standard Horn

http://www.maplin.co.uk/module.aspx?ITAG=SPEC&ModuleNo=3263&doy=17m12#spec


The operating frequencies only overlap by 1khz and the horn can apparently be wired across the bass speaker without the need for a crossover.

Are these two speakers a good combination for eachother?

Would my circuit be as simple as:

Speaker input at binding post -> Bass Speaker -> Speaker binding post

and the horn wired parallel across the bass speaker.

with just simple wires and no other components needed?

Is there a particular design that is needed for high frequency speaker cabinets?

Please may you use relatively simple technological language as there are probably many speaker related words which I don't understand.

Thank you for any help :)
 
What will you use the finished speaker for?

It'll be OK as a 'party' PA unit, but won't be hi-fi.

No need for anything special as a high frequency cabinet, but what's your design for the bass cab?


You can just run these drivers in parallel - not the best way, but they will work - but note that this is because the HF unit is a piezo type: you couldn't do the same with a moving-coil tweeter without destroying it almost instantly!
 

Pano

Administrator
Paid Member
2004-10-07 6:05 am
Panama
I'm sure you'll get a lot of online advice about this one, so let me start.

Yes, it will work. All you need is a series resistor on the horn.

But..... It's going to sound pretty bad. There are tons of cheap PA/DJ boxes out there that are made like this. The universally sound awful.

Asking a normal 12" to work up to 4K is looking for trouble. Crossing at 2K you would be much better off.

A Piezo tweeter can sound better if you do a little work, search the forum, there are some suggestion about using piezos here.

So yes, it will "work". But it won't sound very good. You'll get tired of it fast.

EDIT: DNSEY posted while I was typing. :) I agree with him
 

morfius

Member
2007-09-08 1:43 pm
When you say it will sound quite bad, just how bad do you mean?

Is there a way of improving sound quality with the same sort of setup?

The speaker will simply probably used for parties where volume is necessary.

For the bass cabinet, it will most likely be either cubular or drum shaped with a bass reflex port.
 
When you say it will sound quite bad, just how bad do you mean?

All 'boom and tizz' , and piezo tweeters are particularly tiring to listen to when run as you propose. You've heard the sort of sound many times before at (typically) mobile discos etc.

If you're going to spend 50 quid a side on bass drivers, you might as well do the rest at least half decently!
 
Alright mate,

I have never made a speaker myself so cant offer you any advice but I noticed you have selected drivers from Maplins, I thought you would like a link to firm that sells a range of Hifi drivers in the uk:

https://secure.wilmslow-audio.co.uk/catalog/

I hope this helps. They also sell a range of books on speaker building as well as kits, if you just want to screw it all together.
 
It all depends on your expectations!

I agree with Panomaniac - I've never heard one of these which sounded good, but I have a similar pair, which I use for small speech PA jobs, and they're fine for that.

Give us an idea of your budget, expectations (sound quality, loudness, size of room, style of music etc.), and what you'll be using to drive the speakers, and you'll no doubt receive a lot of suggestions for possible systems.

OTOH, if you just want something cheap & cheerful for parties, why not go for something like the Skytronic range of drivers, which will do the job just as well, and save you money.
 

morfius

Member
2007-09-08 1:43 pm
Can you tell me more about the skytronic drivers and would I still be using the tweeter, sub combination without the need for a crossover?

For the subwoofer, is there a specific internal housing volume that is needed and what type is best - sealed or ported?

I expect the speakers to simply be able to produce music at the main frequencies to a quality that can be enjoyed (not world class, but not immensely bad)

Ideally, it should be powerful enough to be used for outdoor parties (loud)

In terms of music, ideally, it should be able to produce powerful bass that may wow people.
 
Hi,

Simply not a good choice / combination of drivers full stop.
Buy some decent PA speakers, 12" or 15" with a large top end horn.

They start at £140 a pair delivered :

[IMGDEAD]http://www.e-av.co.uk/products/SPEFULPASSVP12.jpg[/IMGDEAD]

http://www.djkit.co.uk/product.php?id=1250&cat=237

http://www.wharfedalepro.com/Default.aspx?dsplType=2&pid=58&ParID=56&IdLang=

You spend more, you get better quality, or quantity by adding a pair of subs :

http://www.djkit.co.uk/product.php?id=1254&cat=239

:)/sreten.
 
Skytronic are just an example of the sort of inexpensive drivers you could use:
http://www.wle-shop.co.uk/modules/shop/products.asp?catid=79&rangeid=400

For the subwoofer, is there a specific internal housing volume that is needed and what type is best - sealed or ported?

A sealed cabinet can be any size - but generally speaking, the bigger the better (within reason).

A ported version would give more of the sort of bass you seem to be looking for, but has to be properly designed; do a search on 'bass reflex' for more information.

BTW, you're not asking about a subwoofer, but a bass speaker or woofer.

What's the output of your amplifier, and how big are your parties?
How far will the listeners be from the speakers?

The 'loudness' is dictated by the amplifier power and the efficiency of the speakers.

Don't make the common mistake of running a puny amp flat-out, as this is a sure way to damage your speakers. You'll need an amp with some power reserve to avoid this. It doesn't matter at all if this is more than the rated power of the drivers, as long as you don't turn it up too high!

Back to basics - yes, you can just sling your proposed drivers in a conveniently sized box, and they'll be OK, but it's such a waste when a little extra effort would result in something much better.
 

morfius

Member
2007-09-08 1:43 pm
Well the speaker is actually school work - I am making it for this years Design technology course.

My design consists of either cubes or drum shapes of different sizes holding each particular speaker.

The subwoofer will be in a large box enclosure, with mids/tweeter speakers in boxes of decreasing size above.

The boxes will be stacked in decreasing speaker size and be supported above one another with hollow metal cylinders which will channel the wiring down to the base and binding post in which any necessary electronics will be held e.g. crossovers.

I drew a picture to help you understand better.

[IMGDEAD]http://img137.imageshack.us/img137/7989/speakerdesign1sketchzc3.png[/IMGDEAD]

It doesn't need to be the worlds loudest speaker, however, it would be nice if it could have a decent amount of power for when I take it home at the end of the year.
 
I've been considering a similar project. A 2-way with a piezo tweeter and a 12-inch woofer. I've got the woofer 'cause it went on sale (http://www.mcminone.com/product.asp?product_id=55-1745&catalog_name=MCMProducts), but haven't picked anything else up yet. I'll compare notes with you, and if anyone wants to comment on my thoughts I'd be glad to hear it.

My goals for the speaker are high volume, low cost, nice sounding (as possible, given other requirements), and reasonable size (they should be storable when their services are not required). I'm hoping to get bass down to 50hz.

Upon listening to the woofers in my basement I thought I might be in trouble. They're listed at 97 db efficiency, but when I started to turn them up they became piercing and painful. A random spare inductor in line with the woofer helped a lot. I imagine it was some cone breakup mode that was stabbing me in the ear. From this experience I conclude that running the big PA 12incher full range is a bad idea.

From looking at some random polar plots, it seems like 12-inch woofers start to beam considerably above 2 khz. I want good off-axis response (can't fit an entire party in a small sweet-spot), so I'm gonna cross mine at 2k.

Your piezo doesn't look like it wants to get that low. I've chosen a different one: http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=270-082

'Course I'll have to buy a horn to attach it to. I don't know much about that, but I'm thinking of this one: http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=264-318

My understanding is that while your piezo doesn't need a crossover, it'll sound much nicer if you do one for it. Ya gotta be a little careful, tho, cause crossing a piezo is different than crossing a regular driver. No inductors, for example. Does that mean no inductors in the woofer section either? I'm not sure what to do about that. I did some reading about piezo crossovers a while back, but can't recall where at the moment. Also, as party speakers they'll need to kick out some bass info, so I'm planning on a BSC. I'm thinking 2nd order for the crossover, but don't have any real justification for it.

Good luck. I don't think going no crossover will be a good idea. But don't be afraid to build it. If you put it together and it sounds terrible you can always go back to the drawing board. In the end I think you'll want a lower crossover point than those tweeters can do, though.
 

morfius

Member
2007-09-08 1:43 pm
We are not given a brief, we are allowed to choose to make whatever we want - whether it be a deck chair or coffee table etc...etc....

The course title is resistant materials - i.e. our product is made from most common hard materials (you can't make a beanbag as your project)

You said to leave styling for later - I thought that the stacked box design is quite flexible?