Budget dorm room speakers

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Recently, a friend of mine in my dorm gave me a set of old busted up speakers. He said to take 'em for free because they were old and probably didn't sound too good. Little did I know (about 2 weeks later after just having them sit around) that they were JBL century L100 speakers, which are right now going for a good 2-300 a pair on ebay. I cranked these guys up and I realized that for my dorm next year, I need serious sound. Seriously BIG sound. Sound that only large drivers in large cabinets can make (ala L100 speakers). So, in honor of the free speakers, here is my next endeavor. Critique it as much as possible, as this is far from anything I've done yet.

The drivers are as follows (you'll see where they all go :D ):

Dayton DVC 10" subwoofer
An externally hosted image should be here but it was not working when we last tested it.


Alesis 6.5" carbon fiber mid/woofer
An externally hosted image should be here but it was not working when we last tested it.


Hi-Vi SD1 1" tweeter
An externally hosted image should be here but it was not working when we last tested it.


Attached are a preliminary 3D look:

Before I ask my questions, here's some other facts. I am not making my own x-overs for these speakers; they would just be too expensive. Rather, I'm going to use one of the Dayton 3-way filters they've got on PE, the one with the 375 lowpass. So, onto the questions:

1. Efficiency, efficiency, efficiency! Do you think that I could push these guys with a receiver to decent output levels, or would I have to run them through an amplifier to get enough power? Remember, these need to have high output levels, but buying dedicated equipment will defeat the purpose of low-cost, so let me know what you think on that.

2. The bottom chamber is 3.87 cubes tuned to 36.5hz, which should be sufficient to pick up any and all low end that these have to offer :bigeyes:. Point being, do you think that a tuning this low, with the edge of the passband rolling off around 350hz would cause blending issues with my midrange? The tweeter and mid should be fairly seamless, and I know bass is omnidirectional, but I do not want boomy bass if I'm not trying to throw a party. Yes, I will have other hi-fi equipment in the room, but I want to know just the same.

3. Now for the most and also the least important bit: grilles. Should I use grills on these or not? Here's the necessary and unnecessary reasoning: people like to play with speaker cones. For some reason they just like touching the, pushing in dustcaps or fondling phase plugs. I'm not worried too much about the sub, but some ******* might get curious about what textile tweeters are and might start playing around with it. A grille, although weak, almost always prevents people from touching the cones unless they are a speaker enthusiast. I don't want any accidents either. Now, with that said, they would be really unnecessary as putting grilles on two 10" subwoofers in a cabinet is next to an insult, as they'll just blow them off anyway. Also, I forgot to show that the subs and drivers will all be flush mounted (that's the purpose of the second baffle on the sub part, the angle at the top is for aesthetics only :D ), so they won't actually come in contact with the grilles. None the less, I would use a magnetic grill guide if I did decide to do that, which also defeats the purpose of the grill as I would need two separate ones for each cabinet (different baffle heights).

Lots of info here, but just wanna ask y'all before I do anything...stupid. :scratch:

-Dave
 

Attachments

  • dormmonsterdonerf.gif
    dormmonsterdonerf.gif
    58.8 KB · Views: 320
First, I think you have a good basic concept for these speakers, just one small problem. Unless things have greatly changed since I was in college, a college dorm room, especially a shared dorm room, is pretty small; two beds, two desks, a sink, and a closet. Are you absolutely sure there will be enough room in the room for speakers this big?

It wouldn't be too great, to get to college and discover that the only place you could put the speakers is under the beds.

1.) Efficiency - well actually efficient speakers need less power. Given the size of these ported cabinets, they should certianly be reasonably efficient, meaning that any halfway decent amp will be enough to drive them.

2.) Here I don't think I can personally answer. But I can ask, do I understand correctly that you are trying to make 4-way speakers?

1.) 0hz to 350hz = (1) 10" woofer
2.) 350hz to (guess) 800hz = (1) 10" woofer or depending on the crossover, 0hz to 800hz
3.) 800hz to 3000hz = (1) 6.5 bass/mid
4.) 3000hz to 20000hz = (1) 1" Tweeter

or was this your plan a 3-way system -

1.) 0hz to 350hz = (2) 10" woofers
2.) 350hz to 3000hz = (1) 6.5" bass/mid
3.) 3000hz to 20000hz = (1) 1" tweeter

Just curious.

3.) I suggest removable grilles. Life in the dorms can be pretty rough and tumble. People aren't really noted for being kind or considerate to other people's property. You want to protect all your speaker because, as you readily admit yourself, people can't resist poking at speaker cones.

And NO under no circumstances will your woofers blow your grilles off. If that happens then you absolutely have the wrong kind of grille cloth.

If you are going for the 3-way as I described above, it would seem that you are making serious demands of the 6.5" bass/mid.

I doubt that that helps much, but it might raise some interesting questions.

steve/bluewizard
 
frugal-phile™
Joined 2001
Paid Member
Now on to the speaker

First, the tweeter does not need a separate enclosure. You are wasting space and creating an empty cavity to resonate

2nd, the bracing in the box is wholly inadequate

3rd, with 2 woofers a push-push arrangement would gain you a huge amount in terms of performance.

4th, the use of any crossover not specifically designed for the box and the exact drivers is almost a 100% garantee that you will not get anywhere near the potential of the design. You cite expense. You'd do much better to only use 1 bass driver and spend the extra cash on building a proper XO (even better idea -- see below -- is to toss the passive XO completely

And while we are on the XO. XOs are the hardest and arguably the most important part of any multiway speaker. If this is your very 1st diy effort i would highly recommend something way simplier to execute.

Let me suggest an alternative topology (i'll use PE parts to show an example of the concept).

Lose the midrange and the tweeter and use a midtweeter instead. For example

http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=264-817

An externally hosted image should be here but it was not working when we last tested it.


Then add 1 or 2 of the subwoofers, get a couple plate-amps (2 really is overkill, but gives you 3 dB more efficiency so you can get away with an amp half the size) and biamp -- no passive XOs required (except maybe a cap on the midtweeter.

These are really good bang-for-the-buck and if you take the cost of the XO + the tweeter + the savings on the midrange = $55/side you only need to forgo a couple cups of coffee to pay the difference. It also lets you turn the XO up to 200 Hz to take the load off the midtweeter & let you play louder. It also makes the cap you need for the midtweeter smaller (BTW -- the best place to put that tweeter is in front of the poweramp you use to driver the midtweeter.

http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=300-784

An externally hosted image should be here but it was not working when we last tested it.


This second may not play quite as loud but is almost guaranteed to sound better

Just some other notes ...

1/ the bass will be limited by amplifier power. Because of the nature of the impedance of the woofers and SS amps, 1 driver will play just as loud as 2 (2 will have lower distortion thou)

2/ The cheapest way to get things to play loud is to use more efficient drivers With your $126 per speaker budget something like Maria with Eminence 12LTA + Tweeter would require ~ a 1/4 as much power to go as loud (one would have to consider the comment about dorm room size thou as this box would dwarf yours). You'd need the money you save on drivers to pay for plywood.

3/ What is happening to the L100s?

4/ a receiver (you have one already?) is an integrated amplier with a built-in tuner. It is always nice to have the ability to use the pre & power amps in any receiver or integrated amps separately.

dave
 
i completely agree with dave,

although i still doubt how loud these TBs can play :)

actually i have similar ideas for this,

using j6t from markaudio(jxr6hd clone) by jordan that specs as tweeter, add 1 midbass for the bass-fill, actually there's couple candidates, either using oem martin logan 8 inch alum woofer, or using magnat latest midwoofer which had the alum sink in the magnets, which quite beautiful :)

with simplicity of using active xo or might be pllxo that dave recommend


cheers
 

Attachments

  • magnat.jpg
    magnat.jpg
    63.1 KB · Views: 275
Thanks guys for all the replies. No, this isn't my first DIY effort in the least, i've been fooling around since 2004, which is why I put a special emphasis on the x-over part as it's the first time I've not made my own filter. I have never gone active, however, so I would need help in learning about how that even works.

Yep, I do know that they'll fit in the dorm as I've already looked in it and saw there's ample room. The L100s are going to stay until I find the time and/or money to restore them, and then I'll most likely give them to my father who owned 4 L100Ts back in the early 80s.

Now, onto the actual design. The bracing isn't shown in the enclosure yet as I just made that as a preliminary mock up, but yes I know it needs more. Secondly, I am assuming that is the TB 871s that you showed me as I'm using two of them for full range hi-fi duty in my dorm right now with a simple notch filter to clean them up. Do you think that would be a good way to go for the mid/tweeter range and spend the rest of the money on plate amps? My only concern is that they would instead just be a full range speaker that has a subwoofer attached to it, which I already essentially have (using a dayton RS12 sub with the tb's in my room). And yes, it would be a 3-way xover (two subs, one mid/woof, one tweet). :)

Thanks for all the help guys, I figured I'd ask the experts first. :D
 
frugal-phile™
Joined 2001
Paid Member
_henry_ said:
using j6t from markaudio(jxr6hd clone) by jordan that specs as tweeter, add 1 midbass for the bass-fill, actually there's couple candidates, either using oem martin logan 8 inch alum woofer, or using magnat latest midwoofer which had the alum sink in the magnets, which quite beautiful :)

I was trying to keep my example within his budget. If i was to do this, i'd likely use FE166 or FE167 to get the volume capabilities & efficiency up.

dave
 
frugal-phile™
Joined 2001
Paid Member
lemans23 said:
I have never gone active, however, so I would need help in learning about how that even works...

If you are now using 871 with powered subs you have already gone active.

Secondly, I am assuming that is the TB 871s that you showed me as I'm using two of them for full range hi-fi duty in my dorm right now with a simple notch filter to clean them up. Do you think that would be a good way to go for the mid/tweeter range and spend the rest of the money on plate amps?

What i linked to is acually a 4" (W4-657SH 4" Aluminum Driver). I was never very thrilled with the 871.

Yes, this essentially a full-range with a sub, but choosing a woofer that goes higher than a typical sub so you can XO higher (Called a FAST), giving more FR choice & more volume capability.

If you already have 871s and are happy with them, you could start there. Consider the 871s as a tempoary sat until you can replace them, and spend the budget on getting the bottom together with less compromise. (ie use the same dual VC 10s, add a bigger amp -- you want to make sure whatever you get doesn't limit the XO as many plate amps do (an XO up to 400 Hz would be nice). Once the woofers are together the current sub could be used to help fund sats.

I mentioned Maria earlier. That is my current effort to build a speaker with high enuff level capability to double as a small PA)

dave
 
I understand your reasoning and trust your knowledge over mine, but I am sill worried that the full range would keep up with the subs anyway. That is why I wanted to do a 3 way design instead of relying on the 871s to belt out 80% of the sound. My main dorm speakers are 2-way bookshelves using Aura NS3s (unbadged from the PE buyout) and a dayton pressfit tweeter. They sound wonderful and have good output, and the 871s sound great as well, but just don't have the displacement to make a good party speaker. I just stumbled upon this design, and it's somewhat like what I am wanting to do.

http://www.partsexpress.com/projectshowcase/magna/index.cfm

He even used the same line of subs that I did, so I'm assuming that the 10s would work just as well in a smaller cabinet.
 
Disabled Account
Joined 2007
lemans23 said:

I just stumbled upon this design, and it's somewhat like what I am wanting to do.

http://www.partsexpress.com/projectshowcase/magna/index.cfm

He even used the same line of subs that I did, so I'm assuming that the 10s would work just as well in a smaller cabinet.


Hi,
I like big, bass heavy impressive looking speakers like this too. There's something to be said about raw brute force. It works for me. :)

Not sure why you want to avoid building a xover. Using lower cost parts it wouldn't be too expensive.
 
MJL21193 said:



Hi,
I like big, bass heavy impressive looking speakers like this too. There's something to be said about raw brute force. It works for me. :)

Not sure why you want to avoid building a xover. Using lower cost parts it wouldn't be too expensive.
See, there we go. :) I've made a few fostex BLH designs, and while they are at least to me, the utmost in efficiency, you just can't get "big" sound without big drivers. I used to think you could, but I was proven wrong.

I am not necessarily trying to avoid making a x-over, as I've done is many times already. It's just that with every filter I've ever made, it's always cost a lot of money. I'll look into a 2nd order filter with cheap components, and get back to you though.


:)
 
If you you do need a receiver this is with out a doubt the best deal out there IMHO;)

http://www.harmanaudio.com/search_browse/product_detail.asp?urlMaterialNumber=HK 3480-Z&status=

Stick with a cheap plate amp for the subwoofers and run the rest off the HK 3480.

If your not going for a "pretty" speaker box. I would recommend putting some built in handles in the sides of the boxes. You can buy pro style carry handles or make them. Especially if you use 1" MDF!

Between the ages of 18 and 24 you will move / Change places more times then the rest of your working life!
 
nordhaven said:
If you you do need a receiver this is with out a doubt the best deal out there IMHO;)

http://www.harmanaudio.com/search_browse/product_detail.asp?urlMaterialNumber=HK 3480-Z&status=

Stick with a cheap plate amp for the subwoofers and run the rest off the HK 3480.

If your not going for a "pretty" speaker box. I would recommend putting some built in handles in the sides of the boxes. You can buy pro style carry handles or make them. Especially if you use 1" MDF!

Between the ages of 18 and 24 you will move / Change places more times then the rest of your working life!
The receiver that I'm using to run both my NS3 bookshelves and 871s bookshelves is this:
http://www.bestbuy.com/site/olspage...&ref=06&loc=01&ci_src=14110944&ci_sku=8249745

It pushed the L100s to the point of people from other wings of my RH coming to see what was going on, so I can only hope for similar success with these new ones. :)
 
Disabled Account
Joined 2007
lemans23 said:
The receiver that I'm using to run both my NS3 bookshelves and 871s bookshelves is this:
http://www.bestbuy.com/site/olspage...&ref=06&loc=01&ci_src=14110944&ci_sku=8249745

It pushed the L100s to the point of people from other wings of my RH coming to see what was going on, so I can only hope for similar success with these new ones. :)


I have the Yamaha HTR5760, similar in a lot of ways. 7.1, but I only use the rear surrounds and the centre channel now. Enough power to make some noise.

Will you go with your original driver lineup or switch to the kit offered by PE? This would take most of the work out of the crossover.
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.