Building Towers

neomagus00

Well, I'm toying with the idea of building my own towers, and I'm kinda jumping in without testing the water, cause that's how cool I am...

My idea so far is:
1 subwoofer in the side of the tower
2 mids (the ones i'm looking at are capable of bridging the gap from sub to tweet completely with no need to separate midrange/midbass)
5 tweeters - this is the fun part, McIntosh is using it right now and I'd love to give it a try... for those that haven't heard of it, it's called a Bessel array, and it's simply five tweeters in a line with either the second or fourth one wired out of phase... the resulting interference creates a perfect 180-degree horizontal dispersion (and the tweeter's vertical dispersion pattern) - say goodbye to the sweet spot.

the other unusual idea i'm working with is totally-integrated amplification, simply plug in a signal and a power cable, and you have full-range sound. so far i've chosen a BASH amplifier for the sub, and i'm looking at Audiosource modular amps to build in to the enclosure.

it's designed as it is to fulfill the form-follows-function rule... if built, they're going in a dorm room for at least a year, followed by a small apartment... the lack of space necessitates good bass response from the towers. i also run regular movie nights, and so the large number of people that need to have good sound force the Bessel array.

i've also toyed with the idea of making them bipole towers, but in such a small room i'm not sure that's a good idea.

my main problem at this point is finding amplification for the 1.6 ohm load the tweeters will present. it's a very flat impedance curve, so a 2-ohm-stable amp will do it, but that's awfully low for home theatre, and i'm not sure i can find an amp that can do 2 ohms and still make it sound good...

what do you think?

Mike682

Did you check out the Outlaw monos....Outlaw says the amps will drive any speaker..

Mike682

Here's the link:

http://www.outlawaudio.com/products/200.html#

Spawndn72

If this does not make sense sonicly, then ignore what I am saying. But from an electrical standpoint, if you wire two tweeter in series, another 2 tweeters in series, and then run them in parrallel, then you would have a 4 ohm load. Diagram would look like this:


---o---o---
| |
---o---o---
| |
----o

---

| |
_ +

the circles are the tweeters.

Hope that makes sense.

No mater what I do the vertical lines won't line up where they are supose to go. One set should be at the left and the other should be at the right.

neomagus00

never heard of outlaw, being a CA guy, but that amp would seem to be quite appropriate. it's listed specifically as being able to handle 4 ohm loads, but i've got an email in to them about the 1.6 load...

um... let me make sure i'm getting the right number for this... 5 8-ohm tweets make 1.6 ohms when they're in parallel, but they'll be one half of a passive xover network that sees 4 ohms on the other side, and depending on how i wire it, there might be a third high-impedance section (the high-level inputs of the BASH amp)... with all those speakers floating around out there, what does the amp see?

EDIT: Spawn: yes, i thought about that, the problem is that the single tweeter will get twice the power the others do... unless, of course, i use an 8-ohm resistor in place... then i get 5.3 ohms... cool!

EDIT2: so replace 1.6 with 5.3 in the passive xover... how's that change it?

VR3

Completely forget attempting to make bipolar towers.

The amount of engineering to get the front and rear drivers spaced apart in the enclosure is very extensive...

neomagus00

so the distance between the drivers INSIDE the box actually makes a difference? if so, screw the bipolar idea...

if it's still feasible, does a bipolar tower necessarily mean identical front and rear configurations... i.e. can i get the spaciousness of a bipolar tower with only a mid and tweet on the back of the tower i've already described?

i've also decided that the three-way xover network is a bad idea - feeding an amplified signal to the inputs of the bash amp seems inappropriate when i can simply use the reciever's sub output, split it with a y-thingy, and go from there.

edit: i see from your website that you're involved in definitive (not officially associated i see, but still better than what i've got), and so you know what you're talking about with bipolars... i'll go crawl into a corner now...

VR3

Bipolar is the same exact signal in phase. Mids and highs. You wouldnt need front and rear woofers though or subwoofers.

Definitive Technology gets the desired "delay time" by spacing. They use nothing in the xover network to do this. Mirage may do it differently, but I doubt it...

VR3

Why not pick up a DT BP10B or something? Audio Advisor is blowing out the Mirage OM 9 (or w/e) for 600 or so a pair. Thats a steal.

http://www.audioadvisor.com/store/productdetail.asp?sku=MIROM9B&product_name=OM-9%20Tower%20Speakers%20in%20Black,%20Pair

If you throw 300-400 watts on the BP10B, you will have all the bass you would need for a LONG time. I'm only running 125 watts to them and forget to turn the sub on sometimes, hard to tell really.

neomagus00

i actually did get a chance recently to listen to the BP10B's big brother, the BP7002, and i loved them... they're a big part of my design, actually (in case you couldn't tell)... are those mirage OM-9 towers a good comparison?

they don't include a subwoofer, so i'll have to account for that... i've heard that the bp7002's subs aren't worth the cash over the bp10b and an external sub - i haven't yet tested them enough to know... opinion?

VR3

The subwoofers in the 7000 series sucks.

Sorry but they do. The Supercubes suck. The whole design idea behind them suck. They don't hit low, the SC Reference dosnt even hit below 30hz with force. They just arnt good subs! DT and Polks only common stance, good speakers complete with bad subs...

EDIT: Don't get me wrong, they are a -huge- improvement over the last powered towers series. There is just no real substitute for a seperate subwoofer.

I recomend the BP10B and a SVS cylinder sub, it dosnt take up much of any space at all! There are some mods you can do to the BP10B to make it better too!

As for Mirage, they invented the bipolar technology. But I would take the BP10B over Mirage... But I am obviously biased!

The BP10B can be had for 400-500 on the Bay and Agon if you look.

Just dont get the BP10 (Black tweeter, uses Vifa midbasses and tweets). Crossover mods cost about 40-50 bucks.

EDIT #Infinity: SVS subs are 16" in diameter and can be hidden pretty well...

(I really need to take new pics)


My room is 10.5x10.5x8

neomagus00

yeah, i actually have spent some time looking at SVS subs... a 12 Hz makes me very happy ...

so! i'll take a look around for a pair of BP10Bs... will they have enough bass to hold me over in a small room for a while? (i do have an 8" sub i can probably put into a box for the interim)...

so, ebay, audiogon, anywhere else i should be looking?

VR3

Yeah dude, the BP10B are solid to 30hz - easy. Especially with raw power and placement. They have more force than "audible boom" - they are just tight.....

Very musical bass. Excellent for movies too..

I turn the SVS off for music most of the time to be honest. They dont quite have the force I like for movies.

EBay and Agon are your best bets.