Okay: I am researching installers in the bay area. I have a recommendation from an installer that we tap the output pre Bose amp for the sub and then put a cap inline with the bose so that the door subs are not duplicating sub produced frequencies... They state that this is to avoid a dramatic increase in output of just the overlapped frequencies creating an unbalanced sound or boominess... I agree with the thought process, but don't agree that a cap is the way to solve this problem...

I had suggested that we use a high pass filter or the mono amp's crossover back into the Bose amp, but they stated that there is too much risk of noise (alternator).

So.... any thoughts????

Also, if we had a choice of Image Dynamics or Rockford Fosgate subs, any suggestions? I assume the ID would be the proper choice.... thoughts?


Lee

 

Very interested in the replies - I just bought a JL 12" wedge and one of their mono sub amps to drive it today and am planning to have it installed next week.

Are there any wiring diagrams I should have along for the installer?

E

 

In my audio experience they've considered it a no no to put a cap to interupt the signal. The clean sweeps from JL are the cleanest way to go, cap's can potentially create a problem down the line with the bose system.

 

But the thinking is that a JL Cleansweep is overkill for this application. I was thinking a 3Sixty.2 from RF because of the tuning capability but don't believe its worth the xtra $ unless I am replacing the factory Bose system entirely. Isn't a crossover in the amp the better choice to go back into the Bose? The installer believes the crossed-over signal from the amp won't be enough level to drive the Bose as they require a much higher signal level. Can someone measure the RCA output volage of the Factory HU and tell me what it is and if that seems higher than other RCA signal levels? Something just doesn't seem right to me...

 

The little top amp drives the two rear deck speaker, which play lower octave music or bass/subbass. The two woofers in the doors play the same bass/subbass. What he says will work and is the low budget way around it. Worse comes to worse, if you don't like it, you remove the caps and either stay that way or invest a little more and upgrade.

 

I'm keeping the Bose HU and replacing the amps, adding a sub, and installing front components (rear speakers are for suckers!) I just got a RF 3sixty.2 for $365 BNIB on ebay. There's another one that is currently at $255 with 12.5 hours left to go.

http://cgi.ebay.com/ws/eBayISAPI.dll...MEWA:IT&ih=016

I don't think it's overkill. Do it!

How much were you going to spend on the capacitor? I won't get into the argument if a cap is worthless or not because that's like talking politics or religion: everyone has a passionate opinion one way or the other and they are all wrong if they don't agree with me.

 

He's referring to an inline cap that will filter frequencies. they are cheap. Not a cap to "supposedly" contain a charge for those extra needed bumps in bass.

 

Gotcha! a "bass blocker" type of filter. I didn't read closely and thought he was talking about a capacitor. Carry on...

 

But the open issue is still: Caps used to block frequencies don't change the fact that the amp is still producing the entire frequency range - it doesn't reduce the load, it's a fake way of blocking frequencies, right????? I want to be able to use the entire power of the amp to produce UNBLOCKED frequencies (i.e., mid-bass, mids and high's). Isn't a crossover a better way to go? I was, however, told that the BOSE amps typically require unusually high pre-amp levels and therefore, I would likely get noise! Is this true? Can someone confirm the pre-amp level voltage on the BOSE HU so that we can compare? I cannot imagine that the level expected by the BOSE amps would be significantly higher than another amp manufacturer - isn't there a standard range for pre-amp level???

L

 

I am not following you. Do you want just to add an amp to drive a sub or to drive all of your speakers? If the latter, it is not advised since the Bose speakers are designed to be used with that amp. It's not a normal setup since the speakers are probably designed around the frequency response curve they wanted. The load of those speakers are most likely lower than what you would want. This is so they can have that small amp have an easier load to work.

I haven't measured it, but I was told that the voltage is 1.5 or 3 V summed for the incoming signal. It's a balanced signal so you cannot just hook up rca's or you will get an annoying noise (ask how I know). The caps will just block the upper frequencies from going to the woofers in the doors. It will do nothing else to the rest of the system. There is already crossing over happening in the Bose Amps. This is why its advised to take the signal before it goes into any of the amps. our guy is proposing is ok, as long as you are just adding a sub and amp to push the sub.

 

So if its a balanced signal and I tap before the amp, don't I need to convert from balanced to unbalanced or use an amp that can handle a balanced in?

 

Have the guys that done this tuned the sub with the Drivers sound stage off or on?

Any recs?

E

 

you definitely need to use a balance to unbalanced converter or go balanced in. If not you get an annoying high pitch whine. I tried to just use RCA in, but no go. I spliced in a symbilink balance cable and all gone.