Subwoofer amplifier for a BIG sub

[Lattiboy]

Hi all,

on a lark I find myself the proud owner of an RBH SV-1212NR subwoofer. This thing is 38” tall, weighs 110lbs, and is completely passive.

I’ve got a lot of questions, but the two most pressing are these:

1) I’m using a XLS 1502 in bridged mode. The sub is rated for up to 2400W, so the seemingly absurd 1550W the Crown is producing isn’t even approaching max power consumption. Would there be any benefit in getting a 2502 which operates at 2400W bridged? Should I have the low pass filter active on the Crown? Is the “high sensitivity” setting appropriate for an LFE outpur

2) my front end is a Denon X3600H. I’ve setup subs with audyssey before, but this thing seems to have a bit more trouble. My main speakers are Canton CT120s which go down to 22Hz, so what crossover settings to use and how to configure the speakers would be helpful. I think I want to set the Cantons to small, but I’m just not sure. Should I have LFE+Main active? Is it advisable to crossover at 80Hz still?

thanks

 

[Grandzoltar]

VtV ucd2k amplifier $819 has 34db gain and reaches its rated output at 2.3v. I doubt you would want to spend big money on the nc2k for just a subwoofer. Since the x3600 has pre out voltage that reaches that high and assuming the subwoower pre out has that as well this would an excellent subwoower amplifier.

 

[CDMC]

1) I’m using a XLS 1502 in bridged mode. The sub is rated for up to 2400W, so the seemingly absurd 1550W the Crown is producing isn’t even approaching max power consumption. Would there be any benefit in getting a 2502 which operates at 2400W bridged? Should I have the low pass filter active on the Crown? Is the “high sensitivity” setting appropriate for an LFE outpur

The difference between the 1502 and 2502 is about 2db output. Also, it is likely that you will exceed the capabilities of the drivers in the deep bass with the amp you already have. I would not spend the extra money to change amps. I would not enable the crossover and let your Denon handle those duties. Leave the sensitivity in the normal position, which provides maximum output at 1.4v input and it the normal gain for most amplifiers.

2) my front end is a Denon X3600H. I’ve setup subs with audyssey before, but this thing seems to have a bit more trouble. My main speakers are Canton CT120s which go down to 22Hz, so what crossover settings to use and how to configure the speakers would be helpful. I think I want to set the Cantons to small, but I’m just not sure. Should I have LFE+Main active? Is it advisable to crossover at 80Hz still?

Cross it over at 80hz. Your Cantons use an 8" woofer and realistically are probably rolling off starting at about 40hz. Good crossover design says that your drivers should be linear for an octave above and below the crossover frequency. You could do 70hz, but there is no point. By high passing your Canton's you will take the deep bass duty load off them which will decrease the woofer's distortion (and make them sound cleaner through the rest of the bass range) and allow greater dynamic capability for the speakers.

What did you do with your old subwoofers? You might want to run those also to get the benefits of room smoothing.

 

[Lattiboy]

The difference between the 1502 and 2502 is about 2db output. Also, it is likely that you will exceed the capabilities of the drivers in the deep bass with the amp you already have. I would not spend the extra money to change amps. I would not enable the crossover and let your Denon handle those duties. Leave the sensitivity in the normal position, which provides maximum output at 1.4v input and it the normal gain for most amplifiers.



Cross it over at 80hz. Your Cantons use an 8" woofer and realistically are probably rolling off starting at about 40hz. Good crossover design says that your drivers should be linear for an octave above and below the crossover frequency. You could do 70hz, but there is no point. By high passing your Canton's you will take the deep bass duty load off them which will decrease the woofer's distortion (and make them sound cleaner through the rest of the bass range) and allow greater dynamic capability for the speakers.

What did you do with your old subwoofers? You might want to run those also to get the benefits of room smoothing.

Thanks a lot. I’ll switch up the input sensitivity on the Crown and see what happens. I knew the 3600 outputs very high pre out voltage for an AVR, but I’ve always heard LFE was lower across the board. Also good to know about the 2db thing. It seemed insane that 1550W wouldn’t be enough.

I sold the old subs and honestly hadn’t planned on replacing them as the Cantons really do go down to 22Hz, but for movies and some dance music you really can’t get what you want without a sub.

 

[CDMC]

Keep in mind that is your in room response. You are likely seeing room gain starting at about 35-40hz which is propping up the bass (as most normal sized rooms do) and the real rolloff is starting at about 35-40hz. Also, as you are undoubtedly aware, a pair of 8" woofers will be strongly limited in their output. For those drivers, which probably have an x max of about 5 mm, the maximum output for the pair is about 110 db down to about 45hz then dropping off like a rock, about 98db at 30hz, about 78db at 20hz. The RBH you got is likely capable of 120db above 40hz and can probably still do 110db+ at 20hz.

One other detail, your receiver is not outputting a LFE signal. It takes the LFE (if there is one) and combines it with the bass in the other channels and outputs it as a mono signal to your subwoofer.

Enjoy it, that sub should sound really good and have plenty of output (unless your room is more than about 4000 cu feet, in which case it will still work great, just won't be capable of obscene levels).

 

[Lattiboy]

Keep in mind that is your in room response. You are likely seeing room gain starting at about 35-40hz which is propping up the bass (as most normal sized rooms do) and the real rolloff is starting at about 35-40hz. Also, as you are undoubtedly aware, a pair of 8" woofers will be strongly limited in their output. For those drivers, which probably have an x max of about 5 mm, the maximum output for the pair is about 110 db down to about 45hz then dropping off like a rock, about 98db at 30hz, about 78db at 20hz. The RBH you got is likely capable of 120db above 40hz and can probably still do 110db+ at 20hz.

One other detail, your receiver is not outputting a LFE signal. It takes the LFE (if there is one) and combines it with the bass in the other channels and outputs it as a mono signal to your subwoofer.

Enjoy it, that sub should sound really good and have plenty of output (unless your room is more than about 4000 cu feet, in which case it will still work great, just won't be capable of obscene levels).

Thanks so much for that info! Literally my two biggest questions!

 

[CDMC]

I forgot, it looks in your photo like you are using 16 or 18 gauge wire to hook up your amp to your sub. I would use some 10 or 12 gauge to minimize any voltage drop. You should be able to get something like the Belden 5000 series for $1-1.50 a foot depending on 10 gauge v 12.

I sort of don’t want to know because I will be jealous, but saw you scored a really good price on your Cantons, how much did you pay for the sub?

 

[Lattiboy]

I forgot, it looks in your photo like you are using 16 or 18 gauge wire to hook up your amp to your sub. I would use some 10 or 12 gauge to minimize any voltage drop. You should be able to get something like the Belden 5000 series for $1-1.50 a foot depending on 10 gauge v 12.

I sort of don’t want to know because I will be jealous, but saw you scored a really good price on your Cantons, how much did you pay for the sub?

thanks, that was temp cable just to test, I have 10 gauge finished cables on it now.

I paid $500 for the amp and the sub. It was somehow up for three days with no other bites. Absurd!

 

[CDMC]

thanks, that was temp cable just to test, I have 10 gauge finished cables on it now.

I paid $500 for the amp and the sub. It was somehow up for three days with no other bites. Absurd!

Wow, that was a steal. Enjoy.

 

[Chrispy]

thanks, that was temp cable just to test, I have 10 gauge finished cables on it now.

I paid $500 for the amp and the sub. It was somehow up for three days with no other bites. Absurd!

Score!