B460 - BX63/BX63A really needed?

Currently using a crown XLS bridge mono w/ lowpass filter @88hz (sounds OK this way) for a B460 sub 2245H. Mains are L300's cut at 50hz using another crown xls (well today anyway :))

I do have a BX63 and always used it, but I don't need to pass the mains thru it in order to remove low frequency to the mains, and so the only feature I was interested in was the 25hz/6db or so boost. It seemed when I have the BX63 in use, (with whatever amp used actually), I could not hear this boost, or I suppose its ability to keep it flat down to 25hz.

I have moved the BX63 in and out with the crown, but I can't hear the difference. The electrolytics inside have been replaced, and seems to function normally.

Maybe the need to have a BX63 is room dependent, placement, etc., My room is small but has lots of treatment for bass in corners. The system is not used for HT, only music.

I got a BX-63A long before i got a B460 - so when I got the B460 a couple months ago, planning to drive it with the same HK Citation 22 bridged to mono (500+ watts) like the 4641 I had in that spot before, I looked to connect the BX-63A - and found I didn't really need to use it on the SUB leg of my Integra HT Processor. I may try it again at some point - I know its got a low end "bump" I am not getting by not using it, but everything sounds so nice and musical as is, i just want to complicate the signal path if its not needed.

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Originally Posted by jfine

Currently using a crown XLS bridge mono w/ lowpass filter @88hz (sounds OK this way) for a B460 sub 2245H. Mains are L300's cut at 50hz using another crown xls (well today anyway :))

I do have a BX63 and always used it, but I don't need to pass the mains thru it in order to remove low frequency to the mains, and so the only feature I was interested in was the 25hz/6db or so boost. It seemed when I have the BX63 in use, (with whatever amp used actually), I could not hear this boost, or I suppose its ability to keep it flat down to 25hz.

I have moved the BX63 in and out with the crown, but I can't hear the difference. The electrolytics inside have been replaced, and seems to function normally.

Maybe the need to have a BX63 is room dependent, placement, etc., My room is small but has lots of treatment for bass in corners. The system is not used for HT, only music.

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Attachment 82533

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Originally Posted by hjames

I got a BX-63A long before i got a B460 - so when I got the B460 a couple months ago, planning to drive it with the same HK Citation 22 bridged to mono (500+ watts) like the 4641 I had in that spot before, I looked to connect the BX-63A - and found I didn't really need to use it on the SUB leg of my Integra HT Processor. I may try it again at some point - I know its got a low end "bump" I am not getting byt not using it, but everything sounds so nice and musical as is, i just want to complicate the signal path if its not needed.

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Hi, yea I didn't want the extra complication either, but I wonder. Does the BX63 do more of a flat thing down to 25hz, or does it really create an audible (or feel-able) 6db increase in sound @ 25hz?

It's described here.
http://www.lansingheritage.org/html/.../1983-subs.htm

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Originally Posted by rusty jefferson

It's described here.
http://www.lansingheritage.org/html/.../1983-subs.htm

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Hi, yes saw that, also have been looking at *a lot* of threads here,

trouble is, it seems that room size, placement, room treatments, and other "variables" can affect how this 25hz bump from the BX63 sounds, or feels, I guess. Or maybe in a given environment a sub amp with user adjustable filters will work good enough, perhaps better...

Here are actual measurements of a BX-63A The crossover also has a high pass function to help protect from overdriving the woofer. I can easily hear when the BX-63 is switched out??

Rob:)

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Originally Posted by Robh3606

The crossover also has a high pass function to help protect from over driving the woofer.

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That was a feature I must have missed, do you have more details how this works?

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Originally Posted by Robh3606

I can easily hear when the BX-63 is switched out??

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Do you mean just switching out the BX63 bypass off/on, or replacing it with, say, an amp that crosses over at a given point, even 63hz for example?

The high pass is a little hard to explain but you can see it in the asymmetrical shape of the response. It is 10db down in level at 20 hz and dropping like a rock. With a Q of 2 it should be a 6db peak and symmetrical. Yes I mean when I switch it out using the bypass, I use mine to run a pair of B380 clones. You can easily get the same response using DSP built into many amps. I use a crown that has DSP built in for my LFE subs that also use the same basic alignment as the JBL subs.

Rob:)

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Originally Posted by Robh3606

The high pass is a little hard to explain but you can see it in the asymmetrical shape of the response. It is 10db down in level at 20 hz and dropping like a rock. With a Q of 2 it should be a 6db peak and symmetrical. Yes I mean when I switch it out using the bypass, I use mine to run a pair of B380 clones. You can easily get the same response using DSP built into many amps. I use a crown that has DSP built in for my LFE subs that also use the same basic alignment as the JBL subs.

Rob:)

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Ah I see, subsonic protection, got that covered with another solution.

Yes I can easily hear it switching out like that too. I guess what I meant by being able to hear the difference is, the difference between using a BX63, and another xover built in to an amp. Because the BX63 has this 25hz/6db bump, that's what I don't hear. So that brings me to is this 25hz/6db bump really needed for a B460, maybe not in certain environments.

BTW what crown are you using?

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So that brings me to is this 25hz/6db bump really needed for a B460, maybe not in certain environments.

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Well I think that is more of a personal choice. You definitely get more output below 30hz but some people like the B460 and B380 without them. It's your rig and if you like it better without that's your call. I like the added output in my room it seems to work well and it doesn't over power the room, may not work in yours depending on placement and seating position.

I use a Crown XT1 2002 for my LFE subs. It has some decent DSP where I can easily get the same response as a Bx-63 Highpass and all.

Rob:)

Be sure you have established the sub is in correct phase with the full range system (not assumed the normal or inverted output is correct).

It appears from the graph in the build article the unassisted woofer is about 6db down at 30hz. If you aren't able to measure the difference see if you can get either a 30hz test tone or a tone generator. That difference of 6db at 30hz should be audible.

You won't necessarily hear that difference with music however, depending on what you listen to and the source.

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Originally Posted by jfine

Currently using a crown XLS bridge mono w/ lowpass filter @88hz (sounds OK this way) for a B460 sub 2245H. Mains are L300's cut at 50hz using another crown xls (well today anyway :))......

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90hz seems high for the low pass with the full range high passed at 50hz. You are probably getting a big boost in the mid-bass if the sub is in correct phase. I think the BX63(A) is an 18db slope on the low pass. What are you using?

I have generally found crossing over lower (63hz) and increasing gain on the sub if necessary a better way to go.

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Originally Posted by Robh3606

Well I think that is more of a personal choice. You definitely get more output below 30hz but some people like the B460 and B380 without them. It's your rig and if you like it better without that's your call. I like the added output in my room it seems to work well and it doesn't over power the room, may not work in yours depending on placement and seating position.

I use a Crown XT1 2002 for my LFE subs. It has some decent DSP where I can easily get the same response as a Bx-63 Highpass and all.

Rob:)

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Yea probably at this point it's preference, I just get twitches when I read posts like, "the B460 wont work right without the BX63", etc.,

I'm using the XLS2000, same except yours does seem to have the ability to adjust Q on a certain frequency, which should emulate the BX63 close enough, a few hundred more, may think about it.

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Originally Posted by rusty jefferson

Be sure you have established the sub is in correct phase with the full range system (not assumed the normal or inverted output is correct).

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Been thru that one, if polarity is wrong on the sub, in my system, the bass just about vanishes.

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Originally Posted by rusty jefferson

It appears from the graph in the build article the unassisted woofer is about 6db down at 30hz. If you aren't able to measure the difference see if you can get either a 30hz test tone or a tone generator. That difference of 6db at 30hz should be audible.

You won't necessarily hear that difference with music however, depending on what you listen to and the source.

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That's more than likely it, source.

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Originally Posted by rusty jefferson

90hz seems high for the low pass with the full range high passed at 50hz. You are probably getting a big boost in the mid-bass if the sub is in correct phase. I think the BX63(A) is an 18db slope on the low pass. What are you using?

I have generally found crossing over lower (63hz) and increasing gain on the sub if necessary a better way to go.

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Yea I'm still playing around, 88hz is high. I will likely end up lower as I dial things in, I do think there should be some overlap with the mains, just haven't found the sweet spot yet.

A couple of points which maybe helpful.

Only on deep bass are you going to hear the boost and the ELF output of the B460 is going to depend on your listening location and tha of the B460.

For process of elimination try the B460 only with and without the BX63 using a suitable program material ie Jurassic Park sound track. Check the Crown Amp does not have any default ELF protection or a high pass filter in operation.

You will be able to tell by the actual air movement from the ports at a reasonable power level below 30 hertz
If you have a positive outcome you know the BX63 is working.

Alternatively use a sine wave sweep signal.

If it’s a negative outcome check the voltage drive out of the BX63 with REW and see if it compare to Robs curve.
It’s a possibility that someone had modified the BX63 you own if the voltage drive does not show the boost.

If it was a positive outcome I introduce the L300 mains as before and play the same program material.

If there is a difference in the bass at any frequencies you have a sub woofer integration problem.
It could be that the port frequency of the L300 is interfering with the B460 or the L300 woofers are coupling with the B460.

The phase relationship with a subwoofer at bass frequencies can be tricky to adjust. This is why the more sophisticated sub plate amps have a variable phase adjustment. The interference could be causing a dip at one frequency and or a boost (peak) at another frequency.

The phase depends on frequency, your room characteristics (x, y, z dimensions) and the location of both the B460 and the mains. There are some good articles if you Google the topic.

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That's more than likely it, source.

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It's hard to hear 25Hz anyway, so unless you know you're exciting that fairly small frequency range
(lowest fundamental on a normal piano is just above at 27.5Hz) with organ pedals, synth, or explosions,
it would be difficult to discern. Also, 6dB boost may be a significant increase in power, but audibly it takes
on the order of 10dB to seem 2x as loud.

It's not that a b460 won't work without a BX63(a), it's just that it has more potential performance envelope
available with something that performs a similar function... also stresses the amp and driver more.

Always a tradeoff :)