Quoted from jfh:
Forgive my ignorance- does this mean you think the sound of the FF kit can be improved by changing the wiring to the sub?
Maybe, yes...Let me explain this a bit differently.
Normally, when you want to have a speaker dedicated to bass (aka sub, though let me get back to that in a second), you take the stereo signal (preferably mono, but stereo works), pass it through a crossover to eliminate all the dynamic range over a certain mHz, and send it to a large woofer.
Self-contained sub-woofers often contain built in crossovers, because some percentage of the time you will have a traditional stereo source without a sub channel, and the woofer isn't designed for high end, so the crossover is needed to only send low end signals to that speaker.
If you have a source that has a "low frequency effects" channel, or LFE, such as a Dolby Digital decoder receiver, you'll have a dedicated sub/LFE output designed to go into a subwoofer. That signal is designed for low frequencies, so it typically doesn't need a crossover.
So how does this all relate to pinball?
If you have a 80's era game like Bride of Pinbot, the sound card outputs the same signal out all the outputs. They tried to save money by putting a capacitor on the right speaker (high pass filter) and putting a cheap tweeter there, then sending the full signal to the left speaker with a more mid-range capability. They then sent the same signal to the cabinet speaker, without a crossover, and got some more midrange that way. To improve the fidelity further, you can put better mid-range speakers on your back panel, send the same full sound to both, then put a dedicated lower-range woofer in the cabinet with a crossover. (Note that with BoP 2.0, there is no need for a crossover, because there is a dedicated low frequency cabinet channel coming out the amp.)
If you have a 90's era game like Theatre of Magic or TOTAN (WPC DCS), you still have a single signal to both right and left speakers (same problem, cheap right speaker to save money is easy to replace and make more balanced), however, the cabinet speaker is already designed for lower frequency. In other words, similar to a LFE channel on a Dolby Digital setup, you don't need a crossover, there is a dedicated bass channel. Since you aren't using the cabinet speaker for any other purpose, a crossover is unnecessary in that situation. (Stupidly, Williams/Bally used 6" cheap throws for the cabinet speakers, so they sound like garbage, but if you replace with a decent 6" or even better 8", like FF, they sound great.)
Flipper Fidelity kits almost always have a crossover on the cabinet woofers. This is because most speaker upgrades are either pre-DCS pinball machines, OR they are modern Sterns which mostly do not have a dedicated low frequency channel. You need to take out the high end before sending the identical signal to the cabinet speaker.
In Spike 2 machines, what I've just been told by Stern is that they are handled similarly to WPC DCS, in that there is a dedicated cabinet channel, probably lower frequency sent to the cabinet speaker. I say probably because while I know it's got it's own channel, I don't know if they mixed it that way. Therefore, in theory, you shouldn't need a crossover...In fact, it may be mixed so that the cabinet speaker handles more of the lower/mid range. If we strip the mid range from that speaker, we may be losing part of the mix.
The only way for me to find out is to bypass the crossover and compare and contrast.
Does this make sense?