Homemade sub used with Sonus Faber Olympica III

I did it! I added the caps into the circuit changing this 1st order 45hz to a 2nd order 57hz XO. And that was indeed the problem. The JBLs add SO much low bass to the system. And there is no integration necessary as they are crossed over very low so they are just picking up the lowest frequencies the Olympica IIIs are a little lean on AND they are being driven from the same monoblocks the main speakers are. Instead of resorting to a subwoofer that is amplified with a class D, $300 amplifier with a damping factor close to 40, I have a set of Classe' class A monoblocks with a damping factor of 5000 which were $10,000, 8 years ago. What a DIFFERENCE! As long as somebody has 300 watts RMS of good quality power to give their passive subs, I would TOTALLY recommend this method. Huge 1500 watt amplified subs have incredible impact by all means but it is by NO means musical and accurate compared to passive subwoofers being driven by the same amp the mains are. My impedance at the amp's speaker terminals was 8.1 ohms with just the Olympics IIIs and now it is 7.89 ohms. I double checked with a Classe' engineer to see if that'd be a problem long term, and before he answered, he gave an involuntary quick chuckle before he answered confidently, "That won't be a problem at all." Well...that's it. I never thought a passive sub would be such a great addition to a system. I did now switch both JBL crossovers to a 2nd order filter so I have 2 passive subs on this system now. 

Erik,

The JBL is connected to the same + and - binding post as one of the SFs.

I did not measure the woofer impedance at 45hz. The woofer itself is 8 ohms impedance wise so I just calculated that. I overlapped by 15 hz to make sure I was covered. I know the design of high end speakers would not use that method, but for now, without the tools needed to test for impedance at 45 HZ, I used my primitive method. As I said, I know the JBL is pumping out lots of low bass because I can see and hear it very easily when it is playing by itself. When I introduce the SFs back into the mix, the bass decreases back to what the SFs normally put out. To test this even further,  I hooked the JBL up to one amp and one of the SFs to the other amp. When I was on the amp with just the JBL, same thing, big bass. When I swept the balance to the middle where both amps/speakers are firing at the same time, the amount of bass is clearly lower. Now, it is not nearly as much of a decrease as it would be if somebody's two front mains were playing and perfectly in phase...and then you swapped the polarity of one speaker. It is just...less. And then when playing music with the JBL and the SF, and I swapped it over to the SF only, bass that is about the same as when the balance was in the middle. I then swapped the polarity of the JBL and tried it all again. Pretty much the same result but SLIGHTLY better. And I say slightly as if the JBL is 82 degrees out of phase in one direction and then 98 degrees in the other direction. It really just seems as though I add a capacitor in parallel with the driver upstream of the inductor to make this a 2nd order crossover which would change my phase by approximately 90 degrees. Meaning about -8 and +8 degrees out of phase instead of 82 and 98 when polarity is flipped.

Of course, one good measure is to put you hand on the sub and see if things are moving. :)

How, exactly did you wire the subs to your amp and main speakers??

Lots going on here, really lots. :)

No way to tell how you calculated the low pass filter.  Did you measure the impedance of the sub at 45 Hz?

My guess is that you may not have the filter set correctly and/or that it is too low.

Best,

E

I think your solution is add a high pass filter to the Sonus Fabers or use a separate amp to power the JBL.

I should also say that the JBL by itself in this situation puts out, lets say on a scale of 0-10 where 10 is the best bass that can be imagined, bass that is a 7. The SFs by themselves is a 5. The SFs AND the JBL together are a 5. So there is a noticeable decrease in bass low extension and bass SPL when all 3 speakers are hooked up at the same time. The decrease in bass low extension and SPL are identical when I switch the polarity on the JBL in this case as well. So that would find the bass being a 5 as well. This just doen't make sense to me. I understand adding a massive sub with a 1000W dedicated amp will add a lot due to sheer power but there should definitely not be a slight reduction in bass when adding another woofer to the system that is being powered with 300W RMS of Classe' power. 

Millercarbon, you say it isn't a sub and that it is just another speaker, I want to make sure I'm not missing something here. The famed 128H woofer used in the JBL L150A speaker is still in the original speaker box where nothing has changed other than me disconnecting the mid and tweet, completely bypassing the factory woofer crossover and then adding a first order low pass crossover to the woofer. The 12" woofer with the 12" passive radiator in the factory 5 cubic foot massive box finds the -6db at 20hz with these speakers so they definitely go lower than most subwoofers on the market. If I disconnect my Sonus Fabers main speakers, the Classe' monoblock runs only the single JBL and it puts out so much bass I can clearly feel it in my chest and it fills the entire house with low bass. If I connect the mains back up, the bass sounds great...but just as good as the Sonus Fabers are by themselves. If I disconnect the JBL at that point, there is no noticeable difference in sound level or low bass extension. If I swap polarity on the JBL is also seems to be identical when added to the SFs...a whole bunch of nothing. That is why I was thinking it was my 1st order crossover network that was causing my JBL to be 90 degrees out of phase with my SFs. 

Is this because my homemade sub has a 1st order crossover

No.

and the Olympica IIIs have either a second or fourth order crossover

No.

meaning the sub is approximately 90 degrees out of phase to my main speakers?

No.

And if so, I assume I would essentially “Fix” the siutuation by instead adding a second order network to my subwoofer?

No.

These answers have been impossible to Google!

Yes. And you are asking all the wrong questions anyway. The answers to what you actually need to know are provided above.

Hopefully you all can help shed some light on this one! 

I lit that sucker up with a flood light and laser beam. 

If you like to know how low the JBL and the Sonus Faber Olympica III can go, connect the JBL to one channel and an Olympica to another channel and play some test tone.

https://www.youtube.com/watch?v=fwrbFj9r10Y

Good question. I didn't specify that did I. The JBL is connected to the system by 10 AWG speaker cable to the same monoblock that one of the Olympicas is connected to. Since the Olympicas only go down to 30hz and I crossed the JBL over at 45hz, there is very little overlap of frequencies so the overall system impedance is virtually unchanged. 

Its because your "sub" isn't a sub its just another speaker. Its helping smooth response and I'm sure it is better, just not in a way you are expecting or listening for. 

The frequency response of a speaker is only partly due to the driver. A lot has to do with the cabinet. There are websites and YouTube channels that explain the relationship between cabinet volume and bass response, ported and sealed, and other types of enclosures. Long story short you will be able to modify what you have or build something new and it will be better than what you're doing now but not by a lot. Probably you will be even more disappointed after all that work than you are now.

The speakers you have are pretty fine. Combined with true state of the art bass you will be beside yourself with pleasure. The tried and true way to achieve this is with a DBA. It will cost about $3k. A little more if you buy a Swarm from Audiokinesis, a little less if you DIY, which in that case depends somewhat on the finish quality you want. Mine are genuine rosewood veneer and look like this: https://systems.audiogon.com/systems/8367

The Dayton SA1000 amp is the same one Duke uses in his. Also Tim, noble100, and several of us here who have this or very similar DBA. Read the comments. This will be awesome, tight, articulate and tuneful deep bass that integrates beautifully and perfectly with your speakers. This is totally the way to go. 

Parts Express has subs on sale now, with pre-cut DIY kits that make this as easy as possible and are exactly what I did. You can modify like I did to make some or all of them ported, or just build them sealed. Either way will work fine. 

How you connect the JBL to your system? Did you use a separate amp to power the JBL?