JBL L212/B212 Ultrabass - replacement amplifer - bass boost or not?

[Zonker92]

I'm shopping a replacement amp for my B212 subwoofer, and according to some product literature (see first image below), the original amplifier ("Bass Energizer") has a 25Hz, 10 dB boost. Yet according to the service manual (linked here and "screenshotted" below), there appears to be no such boost.

Can anyone confirm or refute the presence of such boost? (Of the plate amps I'm shopping, the most boost I have found is 6 dB at 25 Hz; see here.)

Thanks!

Eric

[Don C]

Take note of the passive equalizer shown as part of figure 7 in the manual.

[Zonker92]

Thanks, Don! I did see that, but page 5 of the manual (bottom-left corner) describes that EQ as being for the low-pass filter rolloff (of about 10dB/octave). It never mentions any bass boost EQ that I could find.

So anyway, regardless of the answer to my question, I'm thinking that this plate amp would offer the flexibility to custom-tailor the boost to suit my room, albeit up to only 6 dB of boost:

https://www.parts-express.com/dayton...ifier--300-807

Or just use a mini-DSP I guess.

Maybe there is boost (and the service manual is wrong), or possibly JBL made a running design change and omitted the bass boost because of excursion problems. Dunno. The upper illustration is certainly inaccurate in its absence of the low-pass roll-off curve.

[dprice]

I use a similar amp (SPA1000) to drive a B460 subwoofer. 10 years, no problems so far. It lives in a box alone away from the sub.

The description of the Ultrabass amp/EQ sounds a lot like the language used to describe the BX63 crossover/EQ used with the B380 and B460. I would bet lunch the same design philosophy was used.

[Zonker92]

Cool; good to know. The B212 has a largish cavity underneath for the OEM amplifier: there should be room for a decent-sized plate amp under there. I'm mentally designing a sort of embedded compartment for same.

[Zonker92]

OK, I've now ordered this Dayton SA230 subwoofer amp, which has bass boost adjustable up to 12 dB at 25 Hz (or higher) and an adjustable 18 dB/octave HPF (OEM amp is 10 dB/octave at what looks like around 45 Hz (though the literature suggests 70 Hz). At 156 watts it should have just over 3 dB more headroom than the factory amp, I reckon.

I guess I'll try it at various bass boost settings with an eye toward what appears to be the factory boost of 10 dB:

http://www.parts-express.com/dayton-...ifier--300-813