Two midbass drivers in one box

bego2

Member
2007-08-31 11:23 am
Hi guys, I have a few questions about building a speaker towers with two mid bass drivers and tweeter. Two mid bass drivers im planning to use are identical. There is a few things that I dont understand, if i have two identical drivers how do I connect them, I would use 8 ohm drivers, so parallel, thats 4 ohms, than how I make crossover? Like i would make for 4 ohm driver or? And the question about TW, Is it a problem to use a 8 ohm TW here, because I have two at home. Any suggestion ?

Thanks.
 
Yes for a 2-way design you would wire them in parallel to achieve a nominal 4ohm load, then you would design the crossover as if it were one driver with half the impedance.

It is no problem to use drivers with different nominal impedances in the same speaker as long as you design the crossover filters to suit each driver. You will also have to deal with the different sensitivities of the drivers.

Note that even though your drivers are 'nominal' 8ohm, they may not actually be 8ohm at the frequency you wish to cross them. The most simplistic way of dealing with this would be to inspect the impedance graph in the datasheets and use the impedance at the crossover frequency to use in your crossover filter calculation.
 
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eriksquires

Member
2013-05-10 4:11 pm
Hi Bego,

I suggest you play with XSim, it's a crossover simulator that is a great way to learn and try out different configurations. You can get data files from Dayton on their drivers and try to create virtual speakers to learn about the process and parts, without spending any money at all. For instance, your questions about impedance, and series vs. parallel could be tested out there.

Using the ZMA (impedance files) you can also learn about the complexities of driver impedance, and how it all combines with a crossover for the final impedance curves.

Best,


Erik
 
well, 2 x 8ohm drivers now seem to be +6db with the same 2.83v.
so the 2 of them (in parallel) look like a 4ohm driver with 92db.
Since running them in parallel and stacked (not mtm), I'd cross definitely @ or below 2khz.

floppy qts on the driver.
I'd assume 5mm xmax.

if the specs seem true, 2 of them go into a 3.2ft3 box (91 Litres) and have an F3 around 49hz.

If you want to go deeper but have less output before bottoming out the drivers, you could do 6ft3 tuned to around 28hz.
 
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Lojzek

Member
2012-02-10 12:12 pm
Croatia
What do you think for a box volume? I want it to play from 40ish
to 4000hz... dance, hause, vocal music, trance..similar music...

Hello countryman!

I have been working with Visaton W170 S-8 once and I still have the
measured TS parameters. Use simulation software like UniBox
or Jeff's Woofer Box Model and Circuit Designer.

software

 

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bego2

Member
2007-08-31 11:23 am
well, 2 x 8ohm drivers now seem to be +6db with the same 2.83v.
so the 2 of them (in parallel) look like a 4ohm driver with 92db.
Since running them in parallel and stacked (not mtm), I'd cross definitely @ or below 2khz.

floppy qts on the driver.
I'd assume 5mm xmax.

if the specs seem true, 2 of them go into a 3.2ft3 box (91 Litres) and have an F3 around 49hz.

If you want to go deeper but have less output before bottoming out the drivers, you could do 6ft3 tuned to around 28hz.


that sounds great, I have monacor dt-254 twiteer that plays good from 2k hz

MONACOR - Products: DT-254

Hello countryman!

I have been working with Visaton W170 S-8 once and I still have the
measured TS parameters. Use simulation software like UniBox
or Jeff's Woofer Box Model and Circuit Designer.

software


Thx Lojzek, that helped toooo :cheers:
 

Lojzek

Member
2012-02-10 12:12 pm
Croatia
So what you said about 3.2ft3 box (91 Litres) you meant a sealed box?

There is no point going nuts about excessive box volume that might turn
up being impractical. This is a simulation based on my measured parameters
of 2 units in parallel in a well stuffed box with 0,5 ohm of DCR (low pass
inductor) already calculated in.
 

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Lojzek

Member
2012-02-10 12:12 pm
Croatia
There is multiple suggestions by Visaton and no one sais you have to
do it exactly like this. Maybe it would be better for your application
to work with only one woofer W170S-4 which has a lower Qts and
therefore more suited for a vented box or a 3 way with one W200S.

Lower box tunings work better in smaller rooms, higher are better
in very large rooms where you don't have such room gain. A basic
logic with higher Qts drivers for vented applications demands that
the box volume be twice as much greater than Vas or more to work
properly without sounding overbloated.

Where do plan to put these speakers and how large a cabinet can you
afford?
 

Lojzek

Member
2012-02-10 12:12 pm
Croatia
The only potential issue you might experience would be not
so ideal bass response. Higher Qts driver in a vented cabinet
has its shortcomings but maybe you won't have anything against
it. So, you could build an 80 litre vented box and see how it goes.
Good news is that you can always put a plug and turn it into a
sealed type which will work good. So, the only downside would
be to put up with oversized looking cabinet for just two 6,5" drivers.

Fb of 35 Hz in a vented cabinet you can achieve with a single BR15.34
of 56 mm length.
 

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Most 6" bass MTM's look like this:

532765d1456057805-classic-monitor-designs-mtm-scanspeak-raal-ribbon-selah-audio.jpg


You can use a dome tweeter too. Not a biggie. Usually about 40L total. Nice idea IMO. I've heard this type. A TMM is pretty much the same thing with the tweeter at the top.

You can model a design easily enough in Boxsim. The Visaton W170S drivers are more your closed box suitable. Being Qts around 0.5.

To get up and running quickly, I'd import this design into Boxsim projekte folder and adjust it.
boxsim-db.de | Boxsim Projektdatenbank

Lose the midrange and give each bass 20L. Shift the placing of the drivers for an MTM arrangement.

From my experiments, a 6kHz notch on 6" bass works well. I'd take on a project like this. I've done this with two 4 ohm Visaton W170S in series for an 8 ohm impedance. It's quite easily adjusted for bass via adjusting the 1.5mH coil, and tweeter level. You have a 90dB tweeter, so I think it'll work. One of my projects here, just to show how the build is done in practise.

547001d1462323951-heybrook-hb1-mk1-monitoraudio-r300-md.jpg


It's worth remembering that placing speakers close to the wall lifts the apparent bass.
 

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bego2

Member
2007-08-31 11:23 am
The only potential issue you might experience would be not
so ideal bass response. Higher Qts driver in a vented cabinet
has its shortcomings but maybe you won't have anything against
it. So, you could build an 80 litre vented box and see how it goes.
Good news is that you can always put a plug and turn it into a
sealed type which will work good. So, the only downside would
be to put up with oversized looking cabinet for just two 6,5" drivers.

Fb of 35 Hz in a vented cabinet you can achieve with a single BR15.34
of 56 mm length.


You mean diameter 15,34 cm ?