bfd thump

[moreira85]

After i installed Behringer PEQ I read that they recommend having it plugged into reviever/processor so that it powers on before the sub to avoid the loud thump. the plug on it has a ground prong so i cannot plug it into my reciever. I tried plugging it into the Pure AV power console switched outlet but it takes a few seconds to power on and I get the dreaded thump.
I then plugged into the always on outlet on the power console and the Behringer now stays on at all times with no thump from the sub.
Any fixes for hooking this up where the behringer can be powered off and on with the rest of the components without the thump?

I was wondering if i hooked it back up to the switched outlet and left the SVS on always on instead of auto if that would help? But I am assuming even if it is always on, as soon as the signal comes through the input the thump would arrive.
__________________

[brucek]

Any fixes for hooking this up where the behringer can be powered off and on with the rest of the components without the thump?

Not that I know of. Why not leave it on all the time like everyone else does - it draws about as much as a night-lite. The rest of your components that use remotes would draw more when turned off than the BFD left on.

brucek

[Wayne A. Pflughaupt]

A used Adcom ACE-515 sequential power director would do it, as long as you are able to plug both the sub and BFD into it. It would power up the BFD first, then the sub in several seconds. On power down the sub would turn off first, then the BFD.

But it'll cost about as much as the BFD did, so I guess you'll have to decided if its worth that much to get rid of the thump. If not - as brucek noted, you can just leave it on all the time.

Regards,
Wayne

[Andysu]

There is no common thump if you use these simple steps!

Always power up
1 AVR first
2 BFD
3 sub bass active

Power down
1 switch off sub
2 switch off BFD
3 switch off AVR

It’s that simple and there are no thumbs.

If you power up AVR then sub followed by BFD of course you’ll hear a mild to loud thumb!

How I power things up here

I first switch on the
1 audio mixer
2 secondary EQ for main sub bass
3 EQ for centre back and centre front
4 audio compressor limiter for the (split-surrounds) which is a common (Hi-Fi stereo NICAM VCR)
5 FBQ2496 for JBL 4645 LFE.1/ Eltax A-12R sub bass for LCRS
6 DCX2496 for LCR matching B-chain JBL control 5
7 Yamaha DSP-100 preamp for centre front
8 Yamaha DSR-70 preamp for left and right surrounds centre back and overhead matrix
9 Pioneer VSP-200 for left and right fronts pre-amp and much, much more!
10 main AVR Kenwood KRF-X9050D THX
11 EQ for left and right sidewall surround arrays
12 EQ for overhead surrounds
13 EQ for left and right fronts

14 Marantz 1030 for sidewall surround arrays (x6 speakers JBL control 1 this is for main use)
15 Marantz1050 for HF left and right fronts
16 Marantz 1050 HF amp for centre and (overhead surround x2 speakers JBL control 1used only now and then)
17 Alesis RA300 LF for main sub bass LFE.1 bridged mono
18 Alesis RA300 LF amp for left and right front
19 Alesis RA300 LF amp for centre and (centre back surround x4 speakers JBL control 1 used only now and then)
20 Eltax A-12R sub bass

21 Panasonic widescreen for regular CRT viewing
22 LCD video projector for as and when use

It doesn’t take me, no more than a few minutes to power up and power down also I wait a while for the amps to warm up, no need for rushing.

[lcaillo]

moreira85 wrote:

Any fixes for hooking this up where the behringer can be powered off and on with the rest of the components without the thump?

A muting circuit with a time delay would be easy to build. Anyone have a schematic of the unit?

[brucek]

A muting circuit with a time delay would be easy to build.

Of course you'd also have to design a circuit to stop the turn off thump (which is usually worse than the turn on).

brucek

[lcaillo]

...and much harder to design around. I wonder if there is a muting circuit in the unit already that could be modified to eliminate the problem.

[brucek]

I wonder if there is a muting circuit in the unit already that could be modified to eliminate the problem.

Not that I know of, but I don't have a schematic.

I did play with the BFD many years ago (tracing the circuits that were involved) attempting to come up with an easy fix for the on/off popping. Anything complicated wouldn't be worth it, since simply leaving it turned on works so well.

As I remember I had no problem with the turn on pop. The analog section had a +/- 15 volt supply for the 4 I/O op amps (NJM4580L). The digital section had a simple three tab regulator +5 volt supply.

The turn on pop was easy to fix with a normally closed relay dragging the balanced outputs to near ground until a delay circuit passed the settled 15 volts through a darlington pair to unmute the relay.

The problem (as I remember it) was that the turn off pop was caused by an entirely different problem. It was caused by the digital section outputting an unknown state when it shuts down and this is DAC'd into a voltage pulse to the output - not uncommon. As a conformation test I disconnected the +5 volt supply from the digital section and then shut the BFD off. The turn off of the 15 volt supply did not cause a pop on shutdown (as expected).

So the fix would be to shut the +5 volt supply last so that the 15 volts was completely off and not driving the balanced outputs, or somehow mute the output on shutdown, or mute the output of the digital section. This would not be an easy redesign, since shutting the power switch off shuts the supplies off that you require to power your shutdown circuits.... a bit of a circular problem.

Anyway, I didn't think it was worth the effort of thinking about any more since leaving the BFD turned on all the time is so easy...

brucek

[lcaillo]

I just leave mine on. But if someone wants to pay enough...