# bfd thump



## moreira85 (Jul 10, 2008)

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.
__________________


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## brucek (Apr 11, 2006)

> 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


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## Wayne A. Pflughaupt (Apr 13, 2006)

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


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## Andysu (May 8, 2008)

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.


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## lcaillo (May 2, 2006)

moreira85 said:


> 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?


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## brucek (Apr 11, 2006)

> 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


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## lcaillo (May 2, 2006)

...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.


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## brucek (Apr 11, 2006)

> 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


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## lcaillo (May 2, 2006)

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


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## paulspencer (May 11, 2007)

I have a similar problem with Ultracurve DEQ. I wondered what people were doing with FBD to solve the problem, but I'm surprised and disapointed to find out that people are just leaving it on. IMHO that isn't really a particularly good permanent solution, for a few reasons:

1. Wasteful of power - you might argue it's not that much, but I think we should all try to do what we can

2. Leaving it on shortens it's lifespan. It's a popular myth that audio components suffer stress on powering up and that it's better to just leave them on. The reality is that there are components inside electronics that have a finite lifespan and where they are left powered up their temperature rises and their lifespan shortens a great deal. Perhaps you see all components are disposable after 5 years, but I'd like the option of long term use and to be able to sell the parts I upgrade. 

3. Unless you have UPS, you can't be sure of continuous power supply. Sometimes power goes out and I'd consider it poor system design if it can't handle power cutting out or coming back on all at once without the dreaded thump. 

4. Not user friendly. What happens if other people use it? What if you have a party? Do you hover around the sound system like a control freak or not let anyone else use it? I had family over for dinner and when I wasn't in the room, they turned off the sound system for dinner. The subs went off with a bang! Oops forgot to tell them not to touch anything but the remote and volume control. 

So what do you do about it?
For those with a big budget, a power strip with power sequencing is a good idea and it's a robust solution, except when power cuts out at the mains, which would defeat it's power down sequence. The most robust solution I know is to only use power amps that have soft start relays. That solves the problem when power up and down - the amp simply provides no power for the thump to get through. The problem is, this means no plate amps in your system. You would have to use DIY subs with more expensive pro amps that have this feature. That rules out Behringer Europower and you need to spend about twice as much. I think it's time plate amp manufacturers started re-thinking their design as it's become so common for people to not simply connect them to consumer electronics. 

More about the Europower. I use it and it's actually a partial solution. When powering up, there is no thump as the PS caps don't charge up quick enough. You see the clip lights go on but it can't send the thump signal through as it's not ready that quick. And when you power down, the lights go on showing there is a thump but somehow it filters it out from what I can tell. I know this because if I use high level sub inputs from the Europower to the subs, I have generally no problem, but if low level signal goes to the sub .... THUMP. The problem happens when I power down the system then power it up again while the PS caps are still charged. Then it's an almighty thump!

Recently I found another solution. I had a play with DCX. It had a noise problem so I removed it, but the relays on DCX removed all thumps. I recently picked up another DCX but haven't tested this aspect yet.


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## Nuance (Nov 2, 2008)

brucek said:


> 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


This.


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## Wayne A. Pflughaupt (Apr 13, 2006)

paulspencer said:


> 4. Not user friendly. What happens if other people use it? What if you have a party? Do you hover around the sound system like a control freak or not let anyone else use it? I had family over for dinner and when I wasn't in the room, they turned off the sound system for dinner. The subs went off with a bang! Oops forgot to tell them not to touch anything but the remote and volume control.


 Not sure how you arrived at this conclusion? If the BFD was set up to be on all the time, you wouldn’t get the thump if someone turned off the system. If you hit the main power button on the AVR or remote, it would stay on.




> For those with a big budget, a power strip with power sequencing is a good idea and it's a robust solution...


What “big budget?” You can get used Adcom ACE-515’s (which is what I use) on eBay all day long for under $100 bucks. You usually need something to plug all your gear into anyway; you can't hardly find a decent non-sequencing unit for that price. If you want something brand new, Carvin makes a nice one that only costs $150.




> ...except when power cuts out at the mains, which would defeat it's power down sequence.


Personally I wouldn’t be worried about that, unless someone lives in a place where power outages happen on a regular basis.




> The most robust solution I know is to only use power amps that have soft start relays. That solves the problem when power up and down - the amp simply provides no power for the thump to get through. You would have to use DIY subs with more expensive pro amps that have this feature.


Now _there’s_ your big buck solution... 

Regards,
Wayne


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## paulspencer (May 11, 2007)

Hi Wayne, 

Keep in mind I'm in Australia with 240V.



> Not sure how you arrived at this conclusion? If the BFD was set up to be on all the time, you wouldn’t get the thump if someone turned off the system. If you hit the main power button on the AVR or remote, it would stay on.


When others are using the system then turn it off, there's not telling what they will do. They will look around, get confused, start turning off switches, and probably in the wrong order. They might just turn off BFD first! In my system I have a slave power up device, so the VCR which I don't use is the master device that switches off everything else. Right now there is a bit of a manual sequence.

When I have my system fully set up I'll use an Emotiva processor as the master device to power everything else up/down and it will be set up so that it will be the most obvious first thing to look at when turning off. By then I'll have to have it all properly sorted.



> What “big budget?” You can get used Adcom ACE-515’s (which is what I use) on eBay all day long for under $100 bucks. You usually need something to plug all your gear into anyway; you can't hardly find a decent non-sequencing unit for that price. If you want something brand new, Carvin makes a nice one that only costs $150.


You guys in the US don't know how lucky you are!
I'm in Australia where things are different. Adcom don't have distributors in Australia on their website, and the international section of Carvin don't show that product. 

$800 is more like what we have to pay. If there was a product we could get here for $200 that would be great. Anyone know any products that are available in Australia or that will work on 240v?



> Personally I wouldn’t be worried about that, unless someone lives in a place where power outages happen on a regular basis.


My system will soon be active so the risk is about to go up. Only just last night I had to have the power turned off when I had work done by the power company. I also don't use BFD, I use Ultrcurve and it runs fullrange so the entire system is affected. Still, if I could get a reasonably priced power sequencer, I'd probably be happy with that.



> Now _there’s_ your big buck solution...


I actually built a speaker protection and muting kit years ago. It was pretty cheap, it just didn't work! :hissyfit: But yes it could get expensive if I only used power amps with relays. The Behringer Europower would need replacing with an amp at least twice the cost, and the A500 replaced with an Alesis. Eventually I'll get this sorted ...


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## Wayne A. Pflughaupt (Apr 13, 2006)

$800? Ouch. For that price I think I’d be manual sequencing, too. 

Have you tried Furman? Their website lists a couple if 240 v sequencers, one of them selling for ~$300 U.S. I’m sure you can find others listed in the “Discontinued Products” link. Maybe you could dig up one on eBay for a good price.

Regards,
Wayne


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## paulspencer (May 11, 2007)

That's the outch one! Funny thing is, pro audio shops don't even seem to know what a power sequencer is! I did find a more affordable one at $330. When I saw those ones you linked, I thought "ok so there must be something cheaper than $800 here!"


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## Wayne A. Pflughaupt (Apr 13, 2006)

We used Furman sequencers on occasion back in the early 90s when I was installing pro audio systems, so I know they've been around for a long time. Maybe you can do a saved search on eBay and wait for one to come up. They must be out there somewhere! Shoot, considering those friends you have who like to fiddle around with your system, maybe one of the models with the key switch is what you need!

Regards,
Wayne


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## paulspencer (May 11, 2007)

lol
Actually after seeing Redgum amplifiers, I liked the idea of a key so I have one on the slave power up device. I can actually disable the system with a key. Maybe I should have used that when I had a party on the weekend instead of that picture of a skull and crossbones with the warning don't turn it off!


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## Andysu (May 8, 2008)

I can’t stress the issue enough,addle::foottap: (switching ON the DCX2496 / BFQ2496 / DSP 1124 first!)
(Amps/subs are the last thing to switch ON) 

I find it to be wasteful to keep the DCX2496 / BFQ2496 / DSP 1124 (turned ON 24/7)

Last thing or (first thing to switch OFF is the amps/sub) followed by the rest of the sound system (DCX2496 / BFQ2496 / DSP 1124)

Therefore! You will have no thump and it doesn’t cost a penny.


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