Fostex P1000-BH frequency response. Really only 270 Hz?

Member
Joined 2020
Paid Member
Hi,

I have the these cabinets with the FE103En drivers. I originally bought them because I was intrigued with the back-horn concept. I now have my bigger back-horn towers, so no more 'novelty' on these. I use them as my computer speakers powered by a Rotel RA-12.

Fostex rates the tuning frequency as 270 Hz. which is crazy-high. Is this 'real' or in the real world would these be outputting lower bass?

I am thinking about 'downgrading' to the ported box as they are tuned to 80 Hz. - question is, should I expect to actually get more and power bass?

My drivers: Fostex FE103En 4" Full Range

My current cabinets: Enclosure: P1000-BH - Back-loaded Horn Enclosure Box for P1000K | Speaker Components| Fostex

What I am thinking of getting instead: Fostex P1000E DIY Kanspea 4" Full Range Speaker Kit - PAIR: Madisound Speaker Components

Thanks!

Ken
 
Almost certainly a typing error.

FWIW, with computer speakers my go-to is sealed with EQ. You don't need much SPL, but the LF extension is nice to have. Current speakers are a pair of Kef HTS3001SE eggs (ports blocked), driven by an old Akai amp.

I use Equaliser APO to implement the filters - it's (free!) software that sits between the media player(s) and the physical outputs. Very useful.

Chris
 
I don't doubt the mathematical tuning of the horn is 270 Hz. but wonder if it is outputting lower bass simple with the cone movement (or something).

Good call on the EQ. I turned down the treble on the Rotel to take the edge off/fatten the mids which works well. Yes, very low levels being on my desk.
 
For maximum bass extention Frugel-Horn Mk3, Sperrin, or a well designed TL.

<snip>

dave

Just FWIW, a sealed box w/EQ will get more LF extension than any of those, but will take a large hit in SPL to get there.

My desktop monitors are flat to 35Hz with 4.5" cones, which requires something like 25dB of boost. The mechanically-limited SPL is 82.5dB at 35Hz at 1m. I sit closer than 1m, though, which puts the maximum SPL up to around 86dB.

For me, tinkering with a new microphone design, 86dB peak is enough, and that would be playing something with lots of bass. Playing acoustic or piano music where there's not much LF content, I can go much louder.

You can play around here: Piston Excursion calculator
To figure out if sealed boxes will get loud enough for you at a given lower cutoff.


The BLHs, TLs, etc will have much higher efficiency in the mid- and upper-bass range than the sealed boxes, of course. They don't have the option to apply LF boost to get the low bass back into shape, though: below their LF cutoff, excursion rises quickly but there's very little output.

An alternative would be a passive-radiator based box, and EQ the result of that. The trick would be to tune the PRs to the lowest desired frequency. The advantage would be mechanical: at the very bottom end, the PRs are doing all the work, which reduces the excursion requirements of the main driver. You'd get a bit more mechanically-limited SPL, which might be useful.

Chris
 
Thanks!

Chris, being I don't need efficiency (I have a beefy 60x2 W integrated amp driving these, and 1m away if I'm leaning back), maybe I should just block the port/opening on my current cabinets and make then defacto sealed?
 
Sure, give it a go. Remember, you do need EQ to get the LF response into line. Just converting the boxes to sealed will probably lose some bass.

Sealed boxes, IMO, are very compromised in terms of output and efficiency, but their advantages of small size and effectively limitless LF response (ie, it's just SPL limited, rather than due to cabinet tuning) means they're actually quite suitable for this application.

Chris