Active line level crossover with subwoofer out - HELP


Hi.

Helping my friend with another challenge. 
Looking for a line level crossover. His preamp does not have a subwoofer out.

What he wants to do is have a high pass filter between the preamp and his power amp. This so his Spendor BC1’s are spared anything below 40 or 50hz. And, the crossover needs a low pass filter to spare the subwoofer the high frequencies. 
Thoughts? 
Thanks!
perkri
erik_squires"Cool part is when you learn to EQ the bass and realize you can fix your room modes."
clearthink:

EQ can not fix, correct, or eliminate room nodes the nodes will always be there all you will do is add distortion and an even more uneven net frequency response plot.
Right. Clearthink is absolutely correct OP and you would do well to listen.

The single most important factor in getting good deep articulate fast and smooth bass response is the number of drivers. The more subs the better. That includes the bass drivers in the full range pair.

The idea of improving the performance of the stereo pair by using a crossover to reduce the load on the amp and speakers, I get that. Its true. The problem is it comes at a cost. Not only the cost of the parts, being much more complex it has to cost more. But also cost in terms of sound quality. If your goal is sound quality that is not the way to go.

What you want to do instead is leave the pre alone and simply add a sub out. The simplest, easiest, and most cost-effective solution is what's called a Line Out Converter or LOC for short. Do a search, you will find them all over. 

The LOC is nothing more than 2 resistors per channel. It does nothing more than reduce speaker voltage down to line voltage, ie about 2V. You can see one here done on my Melody tube amp. https://systems.audiogon.com/systems/8367 Scroll down you will see a picture of the actual mod, two resistors per channel, you can even make out the values and copy this if you want. Or if you want a more complete description and circuit diagram go here https://www.epanorama.net/circuits/speaker_to_line.html

Unlike all the other options mentioned so far this one is true high end. It will make the system better- not different, not worse, but actually better. It is easy. And it will cost about $2. The only real questions are do you want it built in like I did, or outside? And how good do you want it to look? Mine is built in because it worked for me but that's the beauty of mods, you can do it your way. 
EQ can not fix, correct, or eliminate room nodes the nodes will always be there all you will do is add distortion and an even more uneven net frequency response plot.

clearthink (George hifi’s alt?? ) and Millercarbon lack education and personal experience in a home or professional environment with this, so their opinions are incorrect. Fortunately I have personal, home and professional experience in the motion picture industry as well as I am guided by acousticians who have written on the subject.

They’ve also failed to read multiple postings I’ve made citing appropriate links. They are guided completely by feels.

I’ll summarize my position, guided by hands on measurement, listening and acoustics:

You can use an EQ to clip resonant modes. This allows the overall subwoofer level to be lifted.

With bass traps, you can even solve nulls.

Miller is, as always,  flat out, laughably wrong. He and george number 9 will never know it though. The rest of it is so riddled with half truths and falsehoods it’s not worth attempting to dissect.

erik_squires
"
clearthink (George hifi’s alt?? ) and Millercarbon lack education and personal experience in a home or professional environment with this, so their opinions are incorrect."

You are confused, disoriented, and profoundly illogical opinions can not be "mistaken" they are opinions although in this case what we are talking about are facts also you do not know anything about my professional, academic, and scientific achievements, accomplishments, patents, and interests. 

" Fortunately I have personal, home and professional experience in the motion picture industry as well as I am guided by acousticians who have written on the subject."

You continue to remain confused, disoriented, and simply wrong.

You can add 1,000 Db of correction, you can turn on the lights in you're room as bright as you want or turn them off to absolute darkness you can play your TV loud and/or wear plaid pants the room nodes will still be their, silly!
You are confused, disoriented, and profoundly illogical opinions can not be "mistaken" they are opinions although in this case what we are talking about are facts also you do not know anything about my professional, academic, and scientific achievements, accomplishments, patents, and interests.


I know you don’t believe in acoustics, and you have yet to ever post anything with measurements, and experiments to prove your point.

You just continue to repeat tropes which were dead in the 90s.

Best,

E
OP:

I encourage you to read in the Room EQ Wizard forums, as well as Audio Science Review similar topics.

If you get a measurement microphone, and a miniDSP, I encourage you to try it out.

Best,

E