Recommendations for beginner?

[big314mp]

Well. I've been trying to design a pair of loudspeakers for my dorm room, and am finding that I'm a little over my head.

I would like:
1) High sensitivity, since I like loud music
2) but I also need it to sound good at low(er) volumes
3) I listen to primarily rap/metal/rock, so strong bass is very important
4) Size doesn't need to be restricted too much, but nothing that really stands out (i.e. most likely not transmission line, and infinite baffle is a definite no).
5) The listening environment will be an 11ft by 12ft dorm room, with the speakers by walls
6) *important* I can't break the bank on this project. No hard and fixed budget, but over $1k is a big no, including amp. Amp will probably be a few hundred.
7) Amp is a gainclone, wattage not yet decided, but probably 120W or so per channel.
8) 8ohm/4ohm doesn't really matter, because the amp will be configured accordingly.

I would like to avoid kits/predesigned stuff, unless some thing really hits the spot for the reqs. Driver recommendations would be much appreciated.

[Dave Bullet]

On one hand you are saying you are finding you are a little over your head, yet want to steer away from kits / predesigned stuff?

Maybe if you can tell us what you can't get your head around, then we can help?

If this is your first set of DIY speakers, strongly suggest you build an existing design from a proven designer.

A search should find a number of reputable designers.

David.

[Nanook]

smaller amp. 10 watts in any room with efficient speakers gets loud fast. just don't tell anyone you're using , say, a 20 watt per channel amp. A 120 watt /ch will never break a sweat, but is over kill. Then perhaps better internal components for the amp can be sourced.

I have come to favour pretty much fullrangers exclusively, but that's for me. No crossover, nothing. Just a well put together box, properly designed, using Baltic Birch plywood exclusively.
Fostex and Hemp, come to mind as does EV and Eminence. (not the only ones, but certainly enough with those four brands to keep you busy).

What are you using as a source? cd player. iPod? laptop? All would benefit from a good DAC, the type depends on your source. DIY amp or commercial product? So allow up to say $250 for an amp (commercial or "kit") , hopefully with some sort of DAC included (like the King-Rex, etc). Then decide on the type of enclosure you want, then the drivers that would work in that type of enclosure. Not all drivers are created equal, and some work better in certain enclosures than others (regardless how close T/S parameters might be). Speakers could be cobbled together for very little money. Certainly substantially less than $500. That way you could actually save a little $$$.

stew

[big314mp]

I'd like to design and build the speakers because copying a design feels like cheating Ah well, spose I'll get over that at some point.

I don't fully understand how to choose a driver based on all of the parameters given. I understand that I should match the impedance, sensitivity, ensure that the power handling is appropriate, as well as make sure that there is plenty of overlap between the frequencies (so the crossover network is simpler).

All of those other parameters are like a foreign language. So how to choose a driver when there are a bunch that meet the aforementioned requirements?

I really like both of these designs that I found:
http://www.partsexpress.com/projects...blue/index.cfm
http://www.partsexpress.com/projects...agna/index.cfm

found the magna by wandering around these forums

both of those are a little expensive for my taste though...so are would modifying these designs be best? If so, what do I modify?

[big314mp]

I'll look at those full range drivers and get back to you on them.

The audio source is my laptop's headphone jack, so no DAC, and probably no volume control. Just a simple, constant gain amplifier.

It's 120W per channel because that is the power of the chip I'm using. I may never run the amp that hard.

But then again...I am in college, so the opportunity will present itself

[MJL21193]

Originally posted by big314mp

1) High sensitivity, since I like loud music
2) but I also need it to sound good at low(er) volumes
3) I listen to primarily rap/metal/rock, so strong bass is very important

Hi,
You like bass and that kind of music (me too) forget fullrange. You need a two-way with a woofer (not a midwoofer) that can give good response upto ~2000Hz and a tweeter that can operate down to meet it.
Woofer possibility: http://www.d-s-t.com.au/data/Peerless/850136.pdf
About $50.00 or find one with similar specs. Put this in a vented 35 litre box ( a little bigger than 1 cubic foot).
Find a suitable tweeter and there you have it.
Doesn't need to be any more complicated.
Good luck.

[Nanook]

and your new foray into analog? Hope all is well.

the Peerless driver does look very appealing, and as usual Danish Sound Technology, looks to be of quite high quality. A simple X over could very well suit., with a tweeter capable of a low x-over frequency.

The WAD "dynaudio" clone (as in Dynaco A25), has been tweaked by the original company (Danish Sound Technology) to improve on the original, and because the enclosure is an aperiodic one, has a very benign impedance curve. I have a set of the originals (I've given a pair away to someone in need), and they are very enjoyable to listen to. But they use a 10" mid-woofer.

My encouragement towards fullrangers is that with no Xover, and high sensitivity, things can get very simple, very quickly. Another option is the use of Pro drivers. They tend to be very efficient, but not necessarily deep in bass, a 12" may only play to what the 8" Peerless does. A 10" Eminence midbass might be interesting, 97db@1watt@1metreand top frequency is 3800Hz, so a good low fs tweeter can be used with a low order Xover..but look for one in the 93-94 dB sensitivity range to match the woofer in baffle.

[BHTX]

First, size and sensitivity versus low frequency extension tend to work against each other. You need to realize which is most important to you for this project. With your mentioned 120 watts per channel on hand, for example, that would be plenty of power to drive most any conventional loudspeaker to decent listening levels. With that said, along with other statements you've made regarding your guidelines and listening preferences, I'd place emphasis on obtaining good low frequency response from something of a decent size. Since you stated that size is a factor, this pretty much rules out pro drivers. As for fullrange designs, I don't think it'd suit you at all, except for the fact that it's often as simple as it gets when done correctly. As for simplicity, a successful 3-way will usually be much more difficult to design than a really good 2-way. With that said, you need to decide how much you really want to put into this as far as time and money are concerned. However, be aware that with a 2-way, your xo point will be in a critical frequency range, and you'll be forced to choose a driver/box combination with hopefully enough low frequency response to satisfy you, yet a smooth enough top end response to blend with a corresponding tweeter that can play low enough to match that woofer and sounds good doing it. Tweeters like these are usually more expensive. So, as far as price is concerned, 2-way versus 3-way, it often evens out somewhat. With a 3-way, a large format high end tweeter isn't always required. However, choosing a 3-way does tend to add difficulty to the design. It just seems tougher to get 'right', at least in my small bit of experience, which isn't really much. Of course, if you were to build a reputable existing design, none of this really matters much, as all the work has already been done for you, and all you'd have to do is buy and build it.

Hope this helps at least a little Goodluck.

[MJL21193]

Originally posted by Nanook
and your new foray into analog? Hope all is well.

the Peerless driver does look very appealing, and as usual Danish Sound Technology, looks to be of quite high quality. A simple X over could very well suit., with a tweeter capable of a low x-over frequency.

Hi Stew,
All is well here, I'm sending you an email.

I have been using the Sony with the Audio Technica cartridge, connected to a jerry-rigged preamp. A slight hum, but that's no wonder considering the setup (see pic).

At random I picked that driver. It has very good response, with a nice low Fs, relatively good sensitivity (89db) and a Qts suitable for the vented box.
I think they are out of production though, as they don't show up at the Tympany site. Solen is selling them for $53.00 Canadian, with a bigger version (10") for $81.00.

Pioneer makes some very decent 2.5" - 3" paper cone tweeters that will cover the 2K-20K range. Cheap too - less than $10.00. A super tweeter could be added for work above 10K, if desired. A single cap is enough for that (if not built-in).