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Old 23rd April 2010, 03:44 AM   #1
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Default First DIY speaker build; need midrange suggestions

Greetings. I'm in the planning stages for building a new pair of 2-way monitor speakers and am collecting information. I've all but decided on the tweeter (Hiquphon OWI) and am currently checking into midranges.

I'd like to go somewhere in the 5" - 7" range, maybe 8". I intend to use a sealed enclosure, but am willing to entertain other suggestions if anybody has insight or knows of a mid that will do what I'm looking for vented.

I listen to a lot of metal mainly, so I need a midrange that has a nice fast attack in the upper midbass and lower midrange, however I'd like a mid that has a lot of midrange energy, too. Something exciting to listen to.

Currently eyeing the Peerless 830883 7", which is pretty close in sensitivity to the OWI (87.5dB and 87dB, repsectively). Anybody have any experience with this driver vis--vis its sound? I'd like to run the crossover at about 2.5kHz.

Anyway, any insight would be appreciated. I haven't even gotten into cabinet finishing or crossover design yet.
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Old 23rd April 2010, 08:21 PM   #2
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You're using a lot of subjective terms in your description of the kind of driver you're looking for -

"...a nice fast attack in the upper midbass and lower midrange, however I'd like a mid that has a lot of midrange energy, too. Something exciting to listen to."

I believe you should instead think about things like distortion, frequency response and efficiency. And find designs that incorporate the drivers you're interested in. An existing design may be an appropriate direction to consider.

Look at Zaph|Audio, for starters.
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Old 23rd April 2010, 09:19 PM   #3
ScottG is offline ScottG  United States
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The subjective stuff is useful.. but what we need information on are more basic things like baffle dimensions and lower freq. response, etc.. (..the 2.5 kHz was particularly useful, but we also need an idea of crossover "slope".)

2-ways usually involve smaller baffles, and that usually requires some baffle step compensation. Further, unless the driver has a high Qts. (about .8), chances are there will be *additional* pressure loss lower in the baffle step region. All of this suggests a driver that is significantly more efficient than the tweeter - assuming you don't want to lower the eff. of the tweeter to match the targeted response of the mid-bass driver.


A suggestion: Beyma 8woofer/p
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Last edited by ScottG; 23rd April 2010 at 09:33 PM.
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Old 23rd April 2010, 09:41 PM   #4
preiter is offline preiter  United States
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For a first timer, it's generally recommended that you build an existing design. There are lots out there.

If you tell us a bit about the music you like, the room in which you will be using the speaker, any size constraints, and the amplifier you are using then I'm sure people will be happy to chime in with some suggestions.
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Old 24th April 2010, 12:28 AM   #5
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Hey, thanks for the replies so far. I'll give you some more info on what I'm looking for and my background.

I've been into car audio since high school, so I have a basic understanding of enclosure design; I usually use WinISD for volumes and tuning frequencies of enclosures. My home audio setups have been hand-me-down until a few years back. I'm currently using some Infinity component speakers in (admittedly terrible) enclosures that I took from a crappy shelf system and performed some surgery on. I actually bought a set of AV-123 ELT 525M speakers recently and hated them. The upper midbass and lower midrange was too muddy and overboosted, and the highs were much too recessed for my liking. Spent a week with them hoping I'd warm up to the sound but it never happened.

I'm in a pretty small room (my office). Eyeballing it, probably about 15' (the side the speakers will be on) x 12' with an 8' ceiling. I sit pretty near-field to my speakers - probably about a 5' equilateral triangle. Amplifier is an Onkyo TX-SR602, however I'll probably chase down an Arcam AVR300 sometime this year yet. I mostly listen to metal (many subgenres), some hip hop, and rarely orchestra. Almost never listen to jazz, blues, etc. I also watch movies on this setup, but it's probably a 90/10 music to movies/games split.

As far as baffle dimensions - since I intend to stay sealed the enclosure will probably have to be split internally. The Peerless 7" woofer I mentioned calls for a .25ft^3 enclosure; just a quick estimate gives me 8 x 8 x 6.75 internal volume - the tweeter will go in a separate chamber above. I may taper the box so it's narrower at the back, as well. I know the owner of a local cabinetry company (they built a lot of cabinets for my parents' remodel), so they'll probably build the box. That said, I'm open to suggestions on materials and construction. Also, I assume I'll need to subtract the displacement of the driver from the internal volume, as well?

Electronics wise, I'll probably build my own crossovers. I've dabbled in hobbyist electronics for a while, and have built my own amplifier. 2.5kHz is the crossover point Hiquphon recommends for the OWI, so that's where I started. As far as slope is concerned, I'm not sure yet. Is 24dB/octave sufficient for these kinds of frequencies? How does that relate to the sound and/or driver selection?

Also, in a sealed enclosure, is stuffing required?

ScottG: Would baffle step be significant in a split enclosure like described above? The chamber itself won't be much larger than the diameter of the mid, and the baffle won't extend more than 1-2" on either side or the bottom of the mid. It will probably extend 3-4" above, however.

Thanks.
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Old 24th April 2010, 12:50 AM   #6
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For a reference there is this design from Projects at DIYSpeakers, can use this different driver instead of the 850439, and adjust for new alignment
Peerless PPB 830874 - 6.5" Poly Cone Woofer from Madisound

Last edited by Inductor; 24th April 2010 at 12:54 AM.
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Old 24th April 2010, 04:31 AM   #7
ScottG is offline ScottG  United States
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Quote:
Originally Posted by Panoptic View Post
.
ScottG..

.

If I were you I'd seriously consider finding a well-documented design (that you like), and building from there. Crossover work isn't just about crossing over from one driver to the next - it also includes tailoring the driver's specific response as it relates to the baffle (or even if there isn't one). No driver is shown with free-air measurements, they are all on an "Infinite" baffle when measured and so what is "flat" almost certainly isn't going to be "flat" on a speaker's baffle. To do even a modest design generally requires both measurement and modeling software. (..a standard 24 db crossover almost never "works".)

IF you are going to do a design yourself then you'll need not only the proper equipment/software, but also a pretty good understanding of that software. You can do this, but it will take time and money (..though these days more time than money). ALTERNATIVELY (in the pursuit of doing it all yourself), you could go the "active-digital" route. That would require an amplifier for each driver (4 for a stereo pair of two-way loudspeakers), and likely this:

Parts-Express.com:Behringer DCX2496 Ultradrive Pro Digital Crossover | omnidrive driverack dps226 soundweb controller

Amplifiers can be purchased or DIY'ed (and easier still that you have done this before).. and there are plenty of forums here for that as well. There are even modification threads on the crossover if you wanted to go this route.

So before we discuss of the particulars, at this point I'll ask:

Which will it be?

1. Full "passive" design yourself? or,
2. Digital "active" design yourself? or,
3. Proven "passive" design from someone else? (..and there are a LOT of good ones to choose from.)

I should add that there are also retail solutions as well.
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Last edited by ScottG; 24th April 2010 at 04:46 AM.
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Old 24th April 2010, 01:17 PM   #8
ttan98 is offline ttan98  Australia
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ScottG is right.
I use active x-over(DCX2496) and mic measurement device to achieve near flat response(if that is what you want).
I am now experimenting with passive series x-over because I can use less components to obtain the Freq. Resp.
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Old 24th April 2010, 08:02 PM   #9
ScottG is offline ScottG  United States
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This isn't good advice.. but I went looking for a mid-bass driver for a sealed enclosure of small size that might work with a standard crossover and the Hiquphon tweeter.

What I came up with is:

GR Research M 165X:

M165X Woofer - M165X
Zaph|Audio

In this size enclosure:

Parts-Express.comayton TWC-0.38CH 0.38 ft 2-Way Curved Cabinet Cherry | speaker cabinet empty speaker cabinet unloaded speaker unloaded cabinet .38 cubic foot curved enclosure curvedsidedCabinets090109
Parts-Express.comayton TWC-0.38BK 0.38 ft 2-Way Curved Cabinet Gloss Black | speaker cabinet empty speaker cabinet unloaded speaker unloaded cabinet .38 cubic foot curved enclosure curvedsidedCabinets090109

With a crossover around 1.9-2 kHz (LR 4th order). (..making sure to adjust component values for the different impedance of each driver at the crossover point.)

It would still suffer some pressure loss in the lower midrange (up to 250 Hz).. but that slightly "leaner" presentation might work well considering the Qtc of the design.

The woofer would need to be placed as far down vertically on the baffle as possible (..right up next to the bottom edge of the cabinet), and the tweeter should be off-set about 1/3rd of the way down from the top of the cabinet and 1/3rd of the way from the outside of the cabinet (or 2/3rds from the "inside" panel of the cabinet) - like this:

Advantages of off-set Tweeter

Ex "B".. but move the woofer down to the bottom edge of the cabinet and the tweeter about 1/3rd down from the top edge.


The problem with all this, (beyond the basic problems discussed), is that I don't think the drivers will give you quite the subjective dynamic response you are looking for.
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Last edited by ScottG; 24th April 2010 at 08:05 PM.
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Old 25th April 2010, 05:50 PM   #10
tomcat9 is offline tomcat9  United States
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Hi Panoptic,
I just sent you a pm.
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