I modeled a B&C 15DS115-4 swap for my Danley TH115s, and the results are interesting.

I’ve been looking at messing with the drivers in my two TH115s, so I put together a Hornresp comparison between the stock B&C 15TBX100-4 and the B&C 15DS115-4. After getting a fresh duratex coating, I ordered the new B&C drivers for further experimentation.

I saw some people online doing this modification, but realized there is very little data about the driver swap. I even found listings where people sold TH115s with this mod. I am suprised how little data there is surrounding this.

I used the reverse-engineered TH115 Hornresp geometry that has been shared around Speakerplans/diyAudio, then updated the driver parameters. I then manually collected response, diaphragm excursion, and impedance probe points for both drivers. I even made sure that the re-created model contained the stock driver that the TH115 had, otherwise the data would be skewed.

For the filtered model I used:

25 Hz Butterworth 24 dB/oct HPF

80 Hz Butterworth 24 dB/oct LPF

The DS115 definitely changes the effective Q of the driver/horn alignment. It becomes more resonant around certain parts of the passband, with a strong rise around 40 Hz and again toward 70 to 80 Hz, while the very bottom end falls off faster than stock at the 2.8 Vrms measurement. (Around 30Hz)

The extra power handling changes the picture quite a bit though. The stock driver is 1,000 W AES, while the DS115 is 1,600 W AES. Once both are compared closer to their rated output, the DS regains the low-frequency sensitivity loss and ends up around 1 dB ahead of stock through much of that lower region.

The biggest surprise is around 40 Hz, where the model shows roughly a 6.4 dB advantage at their respective AES ratings. Around 50 to 60 Hz, where the DS has a noticeable dip at low voltage, the added power and excursion headroom bring it back to roughly stock output or slightly above.

There are a couple ways I could approach the rougher response with DSP. I could tame the elevated 40 Hz and 70 to 80 Hz regions to get it closer to the original TH115 response, or leave some of the 40 Hz rise intact and only smooth the rest of the passband. That would let me actually take advantage of some of the extra output rather than EQing all of it away. That +6dB gain at 40hz would do quite well in most EDM genres, also133dB at 40hz is nasty. I will most likely flatten out the 80hz spike that this causes. 

To fill the 50 to 60 Hz valley, I’d start around 55 Hz, +2 to +2.5 dB, Q 1.0 to 1.2. Then use a broad 75 to 80 Hz cut of about 2 to 3 dB, Q around 1.0 if you want the upper response closer to stock.

I also ordered a CVR DSP-1504, rated around 2,550 W/ch at 4 ohms, so there should be enough amplifier voltage available to make use of the additional driver capability.

Obviously this is still a simulation. The TH115 geometry is reverse-engineered, and Hornresp is not accounting for things like power compression, heating, motor nonlinearity, turbulence, or cabinet losses. It is still useful data, real world measurements will be more conclusive.

I put everything into an interactive graph with a power slider, excursion, impedance, AES/Xvar limits. This reveals stock vs modded comparisons.

Interactive Model: Danley TH115 Mod Simulation

Once the drivers arrive, I’m planning to measure the actual cabinets and see how closely the real-world results line up with the model!

Note: I plugged all of the Hornresp measurement probes into ChatGPT to create an interactive graph to help visualize the data. The actual response, excursion, and impedance data came from the Hornresp simulations I ran manually myself off of driver data sheets, and the modeled TH115 Hornresp file was located on diyAudio.

Danley TH115 B&C 15DS115-4 Swap Data