What to do with really inefficient speakers? Hivi A2S

[EWorkshop1708]

I have some full-range Hivi 2inch speakers I got from Parts Express a few years ago for a small project, however I didn't use them because they are too quiet!

They are the fullest range 2 inch I've heard, I mean they have huge magnets and even put out bass. The aluminum cone makes crisp highs too. I'd really like to use them.

They are rated for 20W but I've put well over 50W and they don't even get warm, but they sound loud only with lots of power, like they NEED 20W minimum!

Should I put these in a really small ported box, or keep them sealed? These are odd speakers!

[j.michael droke]

Originally Posted by EWorkshop1708

I have some full-range Hivi 2inch speakers I got from Parts Express a few years ago for a small project, however I didn't use them because they are too quiet! ...I'd really like to use them. ...Should I put these in a really small ported box, or keep them sealed? ...

Hi there: For enclosures using miniture drivers: checkout the cover of PartsExpress catalog for 2011. Also, on their web site, enter "parts express diy projects" where you will find numerous uses for mini drivers. ...regards, Michael

[60ndown]

could you fit them into the dash of your car anywhere?

[Candisa]

Small fullrange drivers are perfect for line-array speakers. By using multiple fullrangers per speaker, the efficiency goes up a lot!
F.e.: 4 speakers series/parallel = same impedance (=same power out of the amp), but 4 times the cone area --> 6dB more output!

Isabelle

[EWorkshop1708]

Ok, so you have to use many of these drivers.

I may put them close to me on my desk and play them along with my main speakers located further away.

[EWorkshop1708]

Ok, I found the specs on the speaker.

It takes a box internal volume of 0.2 Liters (12.2cu in)

Sealed Enclosure

That's a pretty small box, and I'm about to build two boxes with two drivers each with a tweeter as well, about 24-25 cu in, I REALLY hope that it makes them sound better and louder.

[Bill poster]

Make tiny horn loaded speakers? could be fun

[ghw]

These are 78dB sensitivity on an infinite baffle; any small diameter baffle is going to bring that to 72dB after the baffle-step equalization: utterly useless. There are three reasonable applications for this driver:

1) Line arrays. IMHO this is an inelegant, brute-force approach (and expensive besides). Since the driver has been discontinued, it's probably not even an option.

2) Wall mount-specific, for near-field use. You'd want a triangular prism-shaped box (so the drivers will be toed in to the listener) with a volume >= .2 liters and a generous chamfer (angled cut-away) on the inside of the box. Low-pass to a small, powered center-sub between 90-150hz, depending on your priorities (headroom vs. sub integration). Consider a generous application of 1/2 inch wool felt across the baffle and at the baffle-wall transition to control diffraction. Build a little sub into a briefcase big enough for the speakers and amplification and you could have a neat little near-field rig for the road. Stands/mounts (maybebig suction cups?) would take a bit of ingenuity. If you're going to make it powered and portable, I would look at the cheap 4-channel t-amp boards on Parts Express; one channel for each satellite, two channels to a little dual-voice coil 8" woofer like the MCM 55-2185. Obviously, you would cross at line-level (passive or active can work, but definitely before your amps).

3) Passive, wide-baffle FAST. I.e. cross over to a long-throw woofer with ~84dB sensitivity ala Exodus Anarchy at 300-500hz (expensive but awesome), which is high enough for plenty of power handling, low enough for seamless integration and far enough away from the resonance of the drivers to make the crossover basically textbook without zobels (which would probably break the budget). A decent 84dB woofer will give you deep extension in a small box, tuned low. The baffle step (dictated by the front dimensions of the baffle) should correspond with crossover point: i.e. as the speaker transitions from radiating into 2pi to 4pi space, the more sensitive woofer takes over. To keep diffraction down and construction relatively simple, I would make it look like a miniature LS1. Check out their white paper on the Grimm Audio website to see what I'm talking about: wide baffle, shallow depth, hemicylindrical side-walls.

If any of this was unclear I'm happy to clarify.


George

[EWorkshop1708]

Thanks very much for the suggestions, I got the speakers in their enclosures, it was hard to get them very small, each has approximately 42 cubic inches sealed, no stuffing.

They sound amazing, exceeded my expectations. They take a lot of power, and can get loud now in the sealed boxes. Still much quieter than my main speakers, but having them close makes voice and music clearer, then without them.

A very nice upgrade to my sound system!

The highs are good, I have a custom crossover on the tweeters that brings up the highs, and crossed at high frequency so they blend with the Hivi speakers.

I have a 220uf 100v capacitor to block deep lows, which lets me play them louder, but they have amazing bass for 2 inch if I don't use the capacitor, and still good bass with it.

[EWorkshop1708]

I have them wired internally as parallel, dual 8 ohm drivers, 4 ohms per box. 8 ohm tweeter, 1uf poly cap on tweeter in series with 1 ohm resistor bypassed by 0.1uf