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leif
08-03-2003, 01:41 PM
I have a BX63 crossover between my main speakers and my subwoofer. It is making pretty much noise (deep bass noise).
I suspect something must be wrong with the crossover.
Any suggestions on what it can be?
It is said that the BX63 is the weak point of the B460 sub. Can anyone recommend a better alternative?
Regards Leif

leif
08-03-2003, 02:46 PM
Yes, I only have one B460.
It is said by other owners, for instance on www.audioreview.com
that the sub would be better off with a better crossover network.
I am not sure what would be improved, to be honest.
What I want, is to get rid of the noise it is making. And as you said, I could take it to a repair shop.
And I also would like to be able to change crossover point. I have tried to get a bx63a, but haven`t found any.

Ken Andrew
08-04-2003, 06:00 AM
I owned a BX460 for several years and noticed often the ouput was not notes or pulses but just low frequency noise (garbage).
On most CDs this detracted from the enjoyment because it was obviously not part of the performance or expected to be heard.

It is quite easy to distinguish this from door slamming, motor vehicle traffic, microphone humps, coughs, and feet tapping.

I assumed that these were infrasonics due to poor filtering in the original mastering and only audible because of the extended frequency response of the BX460.

If you set the BX460 at the correct volume for the genuine sounds, the infrasonics are a load on the ears. I eventually decided to sell the BX460.

Ten years later, there is home theatre with exaggarated infrasonics where the BX460 may be OK, but not for hifi.

johnhb
08-04-2003, 10:35 AM
My B460 is the best part of my home theater set up. The LFE output of DD circuit directly to an amp and to the speaker; perfect. For music? I never play it. It is annoying. My mains have plenty of bass.

leif
08-04-2003, 11:56 AM
Let me try to explain the problem a bit better:
The sound is constant. It is deep, and most of it come from right main speaker. Also a little from the sub. The sound disappear if I turn the network to "bypass" mode. And it is on as long as the network is in, and the power amp is in. It is quite loud, and is a constant deep tone. Some guests have asked if there is a car out in the yard with the engine on.
I did not hear this sound before this incident happened: I had bought new power amps, and should connect the system. When turning on, the sub sounded very odd. So I turned the gain on the BX, and then came a big bang from one amp. And that was the end for that amp... I don`t know if I connected wrong, I probably did. And after that, I have had problem with deep noise. No matter if music playing or not. Deep sound is there.

I simply love my sub. I think it is a beautiful furniture. Yet, I see some of you say it is out of date. I have never had another sub, so I can not really compare. What today is common as subwoofers is nothing for me (those small boxes with 8 inces woofers and stuff like that). So I will definately keep it. But would like to solve the noise problem. And if some of you have a bx63A or know one that has, please give me a line. OK?

boputnam
08-04-2003, 05:11 PM
Hey, Lief...

Thanks for describing the event that brought-on the noise - that is very helpful. My post suggesting that seemed irrelevant, so I retracted it - maybe shoulda just left it there, hey? ;)

Clearly, there was something wrong in the set-up, but it could be the BX63 can be serviced. Giskard had a post there recommending that, but the post has "gonned" (this disappearing post thing gets confusing...).

However, I worry about you simply putting a different/new active xover into that signal path without understanding what blew your amp (re: your Marketplace post for a BX63a). It is very disconcerting that increasing the gain on the BX63 blew your power amp. Something is not right.

Maybe you should describe your failed set-up, and someone here will notice what was wrong - it might save you another amp and spare the xover, too. There's some very clever members on this Forum. Just a thought... :hmm:

leif
08-05-2003, 12:26 AM
Well, what I _think_ I did wrong (it was a long time ago) was this: Back on the BX63 there is two jacks for LF out. One marked normal and the other marked inverted.
I put one cable from "normal" to poeramps right input, and one cable from "inverted" to poweramps left input (or was it vice verca). That was not very smart thing to do.
Now I only have one single cable between the bx and the LF poweramp.

I guess I could get some random electronic crossover to do the job, but should those not be custom made for the speakers they should work with? I mean: another crossover would not have the boost in the very bottom to compensate for "the small cabinet" as they say in the brochure.

Ken Andrew
08-05-2003, 08:38 AM
Persist because the B460 will enable you to explore the sub 100 Hz range at whatever volume desired. From memory, the best frequency x-over was 70-80 Hz, so the B460 woofed as the L250 faded away and volume setting was just below audible. These settings ensured you heard anything deliberately recorded but the low-frequency garbage did not intrude on normal CDs.

See the post '250ti Jubilee' about LF content. Remember B460 is intended to partner superior quality normal speakers. I don't think they would match with anything smaller than 12 inch bass on the main speakers.

The driver is so efficient, that deafness is guaranteed with any amp. I found with 350 W amp, that the sound was not as 'fast/controlled' as expected. The Telarc 1812 overture CD is a good example. There is a post recommending 1 kW.

For source material, a recent Australian Hi-Fi magazine article lists 32 DVDs with genuine content in 20-42 Hz range, and 40 CDs in the 5-20Hz range. Unfortunately most of the CDs are not my taste (electronic bass). I have tried several on my 4315, I think something is there but I can't reproduce it.

Earl K
08-05-2003, 11:11 AM
Hi Leif

If it was me, I'd take the BX63a into a electronics repair shop for a checkup of all functions.
It sounds to me like its' putting out some DC offset. This might have been the result of your wiring/cabling misadventure.

regards <> Earl K

Tom Roper
08-07-2003, 02:17 AM
I have the B460 too with brand new 2245H driver, but couldn't find a BX63 crossover.

I ended up copying elements of the BX63, built it, customized slightly by leaving out the crossover and high pass, but leaving the equalization for the LFE channel.

Which brings up the point about why you need the BX63 not just for the crossover, but equalization for the otherwise low frequency rolloff that you would get.

My dolby digital 5.1 decoder supplies LFE output and bass management, for 2 channel audio or DD5.1 movie tracks, 80 or 120 hz crossover. But you still need the equalization the BX63 provides to get the best from the B460.

If anybody wants a sketch of this, I can help. I just hand wired it, kept my grounds together and short, has great signal to noise, perfect!

Just my $0.02, but B460/BX63(custom) is very musical. I love the sound, and it is nice furniture. I use it with (5) LSR28P JBL active studio monitors, and it blends perfectly at the 120hz crossover. You don't even know the sound comes from the B460, seems like the little speakers are doing the whole performance. I used test tones and sweeps, to verify a smooth transition between satellites and sub. Not to gush, but the B460 is tighter, faster, more musical than other subs, and with the proper BX63 equalization, nearly as deep as the deepest for home theater, but more musical.

Key points, you've got to get the hum out of the system. Move your cables around, away from the stray fields where you get noise pickup in the signal. Get rid of the ground loops. Use high current amplification, i.e. Crown, QSC, Carver etc, and lots of it. Mine is 1000 watt 8 ohm bridged mono.

Hum and noise should be no more than 50 db measured at the speaker grill, i.e. about 4 inches from the voice coil.

Peak SPL for mine, measured 1 meter on axis, before clipping or bottoming the voice coil is 123 db. So there is at least 73 db dynamic range. But the point about the B460 again, is not just well endowed power, but musicality.

Tom Roper
08-07-2003, 02:36 AM
Leif, if the problem is inside the BX63, a technician could fix it if he had the schematics. I do, if you need it.

Likely problem areas:
TL084 op amps
Voltage regulator/power supply
capacitors

GordonW
08-07-2003, 09:17 PM
Originally posted by leif
Well, what I _think_ I did wrong (it was a long time ago) was this: Back on the BX63 there is two jacks for LF out. One marked normal and the other marked inverted.
I put one cable from "normal" to poeramps right input, and one cable from "inverted" to poweramps left input (or was it vice verca). That was not very smart thing to do.
Now I only have one single cable between the bx and the LF poweramp.

I guess I could get some random electronic crossover to do the job, but should those not be custom made for the speakers they should work with? I mean: another crossover would not have the boost in the very bottom to compensate for "the small cabinet" as they say in the brochure.

That hookup shouldn't, in itself, have damaged the BX63. In fact, back in the day, I've used that feature of the BX63, to bridge an amp into mono (invert one channel, then use that channel's hot for the negative speaker wire instead of the normal negative terminal). It's perfectly OK to use both, if the situation calls for it.

That being said, I'd agree with those who speculate about possible resistor, capacitor or op-amp distress in the BX63 you have. A noisy resistor or op-amp is the most likely cause, followed by something like a shorted cap causing a DC offset which is then in turn freaking out one of the op amps, which would otherwise have been OK...

As for using something else- yes, the boost IS particular to the B380/B460. The idea for the custom boost filter without crossover is definitely a good one, for those using a dedicated LFE out. However, if you're using the B460 with a 2-channel system, the LP/HP functions would be beneficial...

Regards,
Gordon.

Tom Roper
08-07-2003, 10:30 PM
Very well said.

I've already had one taker on the BX63 schematics. If you need them, I have them in Adobe PDF file. They possibly came from this site, I don't know where exactly. I got them from (many thanks to) Giskard

email me at: motronix@vsdrives or send P.M. to me here.

Tom

leif
08-09-2003, 06:09 AM
Yes yes yes, I really would like if one of you could send me the techical sheme on the bx63.
please send it to [email protected]
They charge about 80US dollars an hour in the repair workshops, so anything that could make the job easier for them is of course a great help.

Thanks everybody for all your help.
I will send the box to the repair shop as soon as I have the sheme, and will give you a feedback how it went. All right?

Regards Leif Arild

Tom Roper
08-09-2003, 08:34 AM
(1) BX63/BX63A schematic sent to address above, Leif.

korgroenewoud
08-15-2003, 01:38 PM
Hi Leif,


I thought i sent you the schematic of the bx 63 a few months ago.

Does it work again ?

Kor