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Author Topic: Use QSC LF-4215 as Sub Alban Birch Film Handler Posts: 63 From: Luxembourg-city , Luxembourg Registered: Jan 2007 posted 01-26-2013 06:20 AM                        Hi Something went terribly wrong and now I'm stuck with 3 SC-443s and only 1 SB-5218. what we needed was 3 SC-423s and 2 SB-5218s. So the mainchannels are oversized and the Sub undersized. What do you guys think of using the 3 LF-4215s as subs together with the SB-5218, which will leave me with SC-423Hs as mainchannel. Amps are all DCA 3 1622 1 2422 1 1824 Surrounds are only 4 SR-26s The room shall 5.1 bi-amped Thanks  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 01-26-2013 07:24 AM                     Without knowing the room, it is impossible to say what the result will be. Combining the LF-4215s with the SB-5218 is probably not wise. The LF-4215 does not have the bottom end. The cabinets were not tuned for that. You could possibly tune them separately to extend their response but you will likely need a lot of amplifier and not have a very efficient system. If you just combine them...you will have an exaggerated mid-bass with very little true bottom end. Look at the response of the LF-4215 Now compare it to the SB-5218 Now super-impose the two but allow for that the LF-4215 is going to be louder given the same power.  |  IP: Logged Marco Giustini Film God Posts: 2713 From: Reading, UK Registered: Nov 2007 posted 01-26-2013 08:44 AM                     Wouldn't be easier just to buy the missing sub?  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 01-26-2013 10:28 AM                     With just 4 surrounds...the room better be tiny anyway! So who is to say that they need more than the one double-18 sub?  |  IP: Logged Alban Birch Film Handler Posts: 63 From: Luxembourg-city , Luxembourg Registered: Jan 2007 posted 01-26-2013 12:55 PM                        I have the possibility to EQ 2 different Subchannels thanks to an AP20 No discussion about the why not buy or exchange against the LFs, the missing Sub please. Not doable. Sorry 4 SR-26 per side. Speced another 4 SRs for the back that's why we habe the 1824 instead of a 1222  |  IP: Logged Marco Giustini Film God Posts: 2713 From: Reading, UK Registered: Nov 2007 posted 01-26-2013 01:35 PM                     I wouldn't ruin the front channels removing the LF. Live with one sub and wait till you have some money for the second one. You still did not mention the lenght of the room, one double-sub may be acceptable for the time being.  |  IP: Logged Bajsic Bojan Expert Film Handler Posts: 190 From: Ljubljana, Si, Eu Registered: Aug 2008 posted 01-26-2013 02:03 PM                     @Marco He will not remove the LF completely from the screen channels, but will use the main speakers appropriate for the room (and the amplifiers). The 443s are the same as the desired 423, but with an additional box of 15" drivers (the LF 4215 box). He wants to use these 3 "now-spare" boxes of LF drivers to serve as a subwoofer. That might not be a good idea as Steve mentioned. Are you sure you cannot trade back the 4215s for one subwoofer? Even at no cost to the provider? I mean, the SB costs the same as one LF4215 list. If really desperate, trade in for two?  |  IP: Logged Marco Giustini Film God Posts: 2713 From: Reading, UK Registered: Nov 2007 posted 01-26-2013 03:04 PM                     Got it, thanks! Is he sure that a room that needs 4x18" wouldn't appreciate 4x15" as well? Anyway what Bajsic says is correct: trade the extra LF back and buy the sub. If the dealer is not willing to do it, trade them yourself as brand new!  |  IP: Logged Alban Birch Film Handler Posts: 63 From: Luxembourg-city , Luxembourg Registered: Jan 2007 posted 01-27-2013 07:05 AM                        2x18" and 6x15" to be precise  |  IP: Logged Marco Giustini Film God Posts: 2713 From: Reading, UK Registered: Nov 2007 posted 01-27-2013 08:07 AM                     SC443 have 4x15" cones and SB5218 have 2x18" each. You claim you'd need 2xSB5218 - hence the 4x18". And I was wondering whether your room - the dimentions of which are still unknown - would appreciate 4x15" (SC443) rather than 2x15" (SB423) - per channel. Am I missing something here?  |  IP: Logged

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