Questions about old school Boston Acoustics ProSeries 12.5 LF

[csermonet47]

Been lurking for a few days now, first post, be easy on me. I have had this sub laying around for years, probably close to 10, just sitting in the basement or garage collecting dust. I just recently got around to fixing the system in my car which was installed by the previous owner(head ache unto itself). The sub set up he had was a little prefab Kicker 8 in a tiny little box to fit behind a door panel, very unimpressive sounding. I decided to build a box for the Boston, per the manuals spec, and replace the lack luster Kicker. The manual says ideal box is a sealed 10.5 x 13 x 13 internally. I've never built one before, but was pretty happy with the outcome, it does appear to be fully sealed, pushing on the woofer cone I do not hear any air coming out, and its quite stiff, leading me to believe its properly sealed. Here are some pictures

The amp for the sub is a MB Quart FX1.400. The sub is the 4ohm model, and the amp is rated for 200w RMS at 4 ohm. So for all intensive purposes, I am running the sub at 200w RMS. I set the gains on the amp by ear, I played a 40hz test tone with head unit at 80% volume until I heard a change in the pitch/distortion, then backed off a tad until it sounded clean. My bass eq setting is at 0, LP filter set somewhere around 80 hopefully, subsonic somwhere around 30 hopefully. I say hopefully because the markings on the amp are vast and it seems to be mostly guesswork when adjusting the knobs instead of getting an exact number. I removed the bass knob remote as well, and the head unit does not have a subwoofer level setting, only bass, which is set at 0. The sub definitely sounds under powered, and from what I have read, it certainly is. However, I can't find a reliable RMS rating for it. Everything is hearsay from forum members. The Boston manual says 50-1200 but does not state whether its peak or RMS, I am assuming the 1200 would be peak. When I adjust the bass eq up on the amp, it definitely will get some thump going to it, but its not consistent, some notes will really hit hard and sound nice, some will not hit very hard at all.

So I have two questions, does anyone know of, or suggest, a more ideal box? And does anyone know of the true RMS rating or have an amp suggestion? I definitely plan on purchasing a new amp, just wanted to get some ideas on what power rating I should be shooting for, and some specific model recommendations would be appreciated. I am thinking about a Soundstream Rubicon 1000, which is rated at 600rms at 4ohms(3x the power I have now) and only $160ish from Sonix Electronics.

Thanks for any responses

[ROLEXrifleman]

1st off, that's a bad ass sub. I ran a pair of them for several years back in the late 90's.

Boston was/is always been different with the way they speced their equipment. I spoke at length with them about it back in the day, b4 O scopes and dd-1's were readily available and there answer was that their numbers were rms numbers on music. Meaning in your case, if your amp was rated at 1200 watts then on music you could show the 12.5lf all 1200 wAtts. The problem with that back them was we adjusted gains by ear and that didn't always work out to well.

I had my 12.5's each on RF power series 250x2's and they took it all day long.

So from a power standpoint I wouldn't have any problems feeding them 1k of clean power. I still to this day run ba pro series components and drive them on a daily with the maximum wattage the manual calls for.

As far as box size.... Don't do it. I tried it in a 1.5 and 2.0 sealed. Didn't like it. Never tried a ported box as only the other series boston had out at he time was speced for it.

Hope that helps, don't fry that sub!!!

[csermonet47]

thanks for the reply. I think I am going to go with an amp that does somewhere in the range of 600-800w RMS. With the sub being 4 ohms, it appears any mono amp that does higher than ~800 at 4 ohms is pretty pricey. The Rubicon 1000 seems like a good value for 600 at 4 ohms.

[ROLEXrifleman]

you'll be safe with that power range.

There are no options that will keep that sub alive very long other than the recommenced 1 cube box. Output is what it is, which is very good btw, but don't expect to be hitting 140db's with it. What you can expect is good clean hard hitting bass down to about 25hz.

[Wicks]

LOVE old school Boston Pro's.

Moar pics!

Especially the backside!

[ROLEXrifleman]

Only bigger

[csermonet47]

Would you guys suggest adding polyfill to my enclosure? I have read alot of (seemingly) contradictory info about it, but I figure it's so cheap and readily available it would be worth a shot. Also thinking about rebuilding the box. My internal dimensions are exactly to Boston's specs, but when I built it I didn't use any glue. I used the wood screws you can see in the picture, and made sure to do a really good job sealing the seams from the inside, and made sure to not mount the woofer ontop of the carpet...but after seeing the build quality of some of the stuff on here, I can do better. And use glue next time

[chrisigz]

I won a sound comp in my Toyota Corolla a few months back with one of these subs for the under 750 RMS section, scored 137db on first run then 137.7db on second only running a 400RMS 2 ohm amp. The sub has a 550/1000 RMS 2ohm/4ohm max power rating for those who want to know. Also sub is in a 1 foot square sealed box.

[Team Bassick - Kimo]

Yeah back in the day Boston Pro's were the high end speakers we carried. We carried the Pro, Rally and Rx lines of Boston's. I recently just put in a set of Pro Series 6.53 in my Silverado. I would of loved to have put in a Boston Pro sub along with it. With the sealed enclosure you should be very happy with the response and accuracy.