[OSIB16]

Could someone please advise me how to slightly boost the bass response of my BEOVOX CX50 speakers by tinkering with the circuit boards. I have already added a bass port tube, but it did not make a significant difference.

[HAL]

The CX50 crossover schematic shows a simple series mode crossover for the woofer and tweeter.

Adding a bass bump would depend on the Thiele-Small (T-S) data for the original woofer and the box volume. 

Most bass boost circuits require active gain to be used external to the box before the power amp and depends on how much excursion the woofer has that is in the T-S parameters. When boosting bass it is easy to overdrive and destroy the woofer.

The EQ would be similar to a bass control on a preamp for boosting the bass.

[Hobbsmeerkat]

Outside of DSP or an equalizer of some kind, another other option to "boost" bass output would be to use a larger gauge coil, as the larger gauge offers less resistance at lower frequencies. it may be a fairly small boost but its worth trying.

If your current coil is 18-20awg coil try a larger 14-16awg coil.

[OSIB16]

Would I be able to add an L Pad for the mid/woofer to artificially boost the bass slightly? Just to give you more information about my modified speakers; They are B&O BEOVOX CX50’s installed into a CX100 cabinet. I swapped the original 6.8uf capacitor for an Audio Note Kaisei 5uf electrolytic capacitor. This has definitely fixed the overbright treble issue that the CX50 naturally suffers with, but the bass is definitely too light. I wonder if it is the Kaisei capacitor that is responsible for this bass issue?

The CX50 crossover schematic shows a simple series mode crossover for the woofer and tweeter.

Adding a bass bump would depend on the Thiele-Small (T-S) data for the original woofer and the box volume. 

Most bass boost circuits require active gain to be used external to the box before the power amp and depends on how much excursion the woofer has that is in the T-S parameters. When boosting bass it is easy to overdrive and destroy the woofer. This is bearing in mind that I have fitted a bass port tube to the rear of the cabinet.

The EQ would be similar to a bass control on a preamp for boosting the bass.

[Hobbsmeerkat]

Would I be able to add an L Pad for the mid/woofer to artificially boost the bass slightly? Just to give you more information about my modified speakers; They are B&O BEOVOX CX50’s installed into a CX100 cabinet. I swapped the original 6.8uf capacitor for an Audio Note Kaisei 5uf electrolytic capacitor. This has definitely fixed the over bright treble issue that the CX50 naturally suffers with, but the bass is definitely too light. I wonder if it is the Kaisei capacitor that is responsible for this bass issue?

If this model used a more traditional parallel network, that would work, but with series networks, changes to part of the network also means changes to the response of the other other driver.
so unfortunately it's not quite as simple in this case.

[WGH]

You can tinker with other parameters to get more bass. The CX50's sensitivity is only 82.6dB/1kHz and 83.8dB (500Hz-8kHz), a more powerful amp with high current would add more bass (until you blow out the woofers). Low frequency extension is limited to just 120Hz plus the low sensitivity means distortion is high at typ. 5-10% through bass/midrange at 90dB SPL. The louder/deeper/lower it goes, the nastier it will sound.



Locate the speakers as B&O intended and they will have more bass and the tweak costs nothing.

"Used like conventional loudspeakers, mounted on stands and positioned well into the room, the CX50s disappoint because they produce so little bass. Matters improve greatly, though, if the loudspeakers are placed as intended, either on well stacked bookshelves or pushed right into the corners of the room."

"Clearly, music with very deep and prominent basslines cannot be played at high levels without audible signs of distress either. After all, there is only so much air you can move with a pair of 8cm-diameter (3") cones!"

Bang & Olufsen Beovox CX50 Loudspeaker Review


https://www.hifinews.com/content/bang-olufsen-beovox-cx50-loudspeaker


The only guaranteed way to get more bass without destroying the CX50 is to buy a little subwoofer like the REL Tzero MKIII
There is a Tzero MKIII on eBay for only $350.00.

[JCarney]

Read this. Full disclosure, I have not read it.

https://www.diyaudio.com/community/threads/open-baffle-bass-boost-4-to-7db-w-passive-xover-no-dsp.404171/

JCarney