power on/off pop problem

[[email protected]]

I'm using a dbx active crossover feeding a couple old adcom amps.
I've rigged it all to go on and off controlled by my "pre-amp" power.
But I get a substantual power on and off pop from both amps. It is
the active crossover causing it because if I leave it out of the
system I don't have a problem. Probably because the crossover is
professional gear and not designed to be powered on and off while in
use. I solved the power on pop by adding a delay to the amp turn
ons. I already had an electronic switch on the amps because the
preamp can't supply that kind of power from it's switched output. But
I still have the power off problem and playing games with the power on/
off sequence is getting complicated. Any solutions? Or add on
circuits?

[[email protected]]

On Apr 8, 8:17*am, wrote:
> I'm using a dbx active crossover feeding a couple old adcom amps.
> I've rigged it all to go on and off controlled by my "pre-amp" power.
> But I get a substantual power on and off pop from both amps. *It is
> the active crossover causing it because if I leave it out of the
> system I don't have a problem. *Probably because the crossover is
> professional gear and not designed to be powered on and off while in
> use. *I solved the power on pop by adding a delay to the amp turn
> ons. *I already had an electronic switch on the amps because the
> preamp can't supply that kind of power from it's switched output. *But
> I still have the power off problem and playing games with the power on/
> off sequence is getting complicated. *Any solutions? *Or add on
> circuits?

To be fair to the dbx, the fact that I am hooking it to unbalanced
inputs on the amps probably contributes.

[Dave]

> wrote in message
...
> I'm using a dbx active crossover feeding a couple old adcom amps.
> I've rigged it all to go on and off controlled by my "pre-amp" power.
> But I get a substantual power on and off pop from both amps. It is
> the active crossover causing it because if I leave it out of the
> system I don't have a problem. Probably because the crossover is
> professional gear and not designed to be powered on and off while in
> use. I solved the power on pop by adding a delay to the amp turn
> ons. I already had an electronic switch on the amps because the
> preamp can't supply that kind of power from it's switched output. But
> I still have the power off problem and playing games with the power on/
> off sequence is getting complicated. Any solutions? Or add on
> circuits?

Adcom, and I'm sure others, sell a power conditioner (model ACE-515 is one I
have seen) which has dedicated outlets for power amps which incorporates a
built-in delay for turn-on. The power amps need to be powered up last, or
some sort of time-delay muting function added, either via a relay or an
RC-timed circuit which depowers the input differential pair (ala H-K).
There is nothing wrong with any of your equipment.

[[email protected]]

On Apr 8, 5:44*am, wrote:
> On Apr 8, 8:17*am, wrote:
>
> > I'm using a dbx active crossover feeding a couple old adcom amps.
> > I've rigged it all to go on and off controlled by my "pre-amp" power.
> > But I get a substantual power on and off pop from both amps. *It is
> > the active crossover causing it because if I leave it out of the
> > system I don't have a problem. *Probably because the crossover is
> > professional gear and not designed to be powered on and off while in
> > use. *I solved the power on pop by adding a delay to the amp turn
> > ons. *I already had an electronic switch on the amps because the
> > preamp can't supply that kind of power from it's switched output. *But
> > I still have the power off problem and playing games with the power on/
> > off sequence is getting complicated. *Any solutions? *Or add on
> > circuits?
>
> To be fair to the dbx, the fact that I am hooking it to unbalanced
> inputs on the amps probably contributes.

Wouln't make a bit of difference balanced vs unbalanced. Some units -
typically the ones that run on single polarity power supply and need
to charge up input / output capacitors almost always pop at power up /
down. Daves solution will fix you right up.

G²

[[email protected]]

On Apr 8, 11:10*am, wrote:
> On Apr 8, 5:44*am, wrote:
>
>
>
>
>
> > On Apr 8, 8:17*am, wrote:
>
> > > I'm using a dbx active crossover feeding a couple old adcom amps.
> > > I've rigged it all to go on and off controlled by my "pre-amp" power.
> > > But I get a substantual power on and off pop from both amps. *It is
> > > the active crossover causing it because if I leave it out of the
> > > system I don't have a problem. *Probably because the crossover is
> > > professional gear and not designed to be powered on and off while in
> > > use. *I solved the power on pop by adding a delay to the amp turn
> > > ons. *I already had an electronic switch on the amps because the
> > > preamp can't supply that kind of power from it's switched output. *But
> > > I still have the power off problem and playing games with the power on/
> > > off sequence is getting complicated. *Any solutions? *Or add on
> > > circuits?
>
> > To be fair to the dbx, the fact that I am hooking it to unbalanced
> > inputs on the amps probably contributes.
>
> Wouln't make a bit of difference balanced vs unbalanced. Some units -
> typically the ones that run on single polarity power supply and need
> to charge up input / output capacitors almost always pop at power up /
> down. Daves solution will fix you right up.
>
> G²- Hide quoted text -
>
> - Show quoted text -

I added a delay on to my power amps and that solved the power up pop.
But I still have the power down pop. I thought about creating a delay
power off for the crossover but screwing around with the powering
sequence is getting complicated.

I'm thinking maybe I should be messing around at the amp outputs
instead.

[PhattyMo[_2_]]

Dave wrote:
>
> > wrote in message
> ...
>> I'm using a dbx active crossover feeding a couple old adcom amps.
>> I've rigged it all to go on and off controlled by my "pre-amp" power.
>> But I get a substantual power on and off pop from both amps. It is
>> the active crossover causing it because if I leave it out of the
>> system I don't have a problem. Probably because the crossover is
>> professional gear and not designed to be powered on and off while in
>> use. I solved the power on pop by adding a delay to the amp turn
>> ons. I already had an electronic switch on the amps because the
>> preamp can't supply that kind of power from it's switched output. But
>> I still have the power off problem and playing games with the power on/
>> off sequence is getting complicated. Any solutions? Or add on
>> circuits?
>
> Adcom, and I'm sure others, sell a power conditioner (model ACE-515 is
> one I have seen) which has dedicated outlets for power amps which
> incorporates a built-in delay for turn-on. The power amps need to be
> powered up last, or some sort of time-delay muting function added,
> either via a relay or an RC-timed circuit which depowers the input
> differential pair (ala H-K). There is nothing wrong with any of your
> equipment.


But to get rid of the turn-off pop,you'd need to delay the turn-off of
the dbx,and turn the amps off first.

[Dave Platt]

In article >,
PhattyMo > wrote:

>> Adcom, and I'm sure others, sell a power conditioner (model ACE-515 is
>> one I have seen) which has dedicated outlets for power amps which
>> incorporates a built-in delay for turn-on. The power amps need to be
>> powered up last, or some sort of time-delay muting function added,
>> either via a relay or an RC-timed circuit which depowers the input
>> differential pair (ala H-K). There is nothing wrong with any of your
>> equipment.

>But to get rid of the turn-off pop,you'd need to delay the turn-off of
>the dbx,and turn the amps off first.

Some years ago I build a power controller to do precisely this. One
outlet for distribution to the source components, one to the Marchand
active crossover (which quite conveniently has an output-muting relay)
and two for the two power amplifiers. Each output is controlled via a
power relay, and the relays are driven by RC-timed circuits which have
settable "attack" and "decay" times. The power-amplifier relay system
is actually a two-stage: a small solid-state relay switches in first
(powering up the amps through an NTC anti-surge resistor) and then the
main mechanical relay closes a second or so later.

At power on, the power amps are turned on first, then the input stage,
and finally the crossover (which unmutes the signal path once its
output is stable). At power off, the power amps and crossover are
turned off, and the input components switch off a couple of seconds
later once the crossover muting relay has disconnected the audio path.

Works really nicely... no nasty thumps on either end, and the
slow-start circuit for the amp keeps the lights from dimming :-)

--
Dave Platt > AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

[Jasen Betts[_2_]]

On 2009-04-08, > wrote:
> On Apr 8, 8:17Â*am, wrote:
>> I'm using a dbx active crossover feeding a couple old adcom amps.
>> I've rigged it all to go on and off controlled by my "pre-amp" power.
>> But I get a substantual power on and off pop from both amps. Â*It is
>> the active crossover causing it because if I leave it out of the
>> system I don't have a problem. Â*Probably because the crossover is
>> professional gear and not designed to be powered on and off while in
>> use. Â*I solved the power on pop by adding a delay to the amp turn
>> ons. Â*I already had an electronic switch on the amps because the
>> preamp can't supply that kind of power from it's switched output. Â*But
>> I still have the power off problem and playing games with the power on/
>> off sequence is getting complicated. Â*Any solutions? Â*Or add on
>> circuits?
>
> To be fair to the dbx, the fact that I am hooking it to unbalanced
> inputs on the amps probably contributes.

you solved one part of the problem by turning the amps on late,
perhaps you can solve the other part by turning the crossover off late?

[Bob Masta[_2_]]

On Wed, 8 Apr 2009 05:17:02 -0700 (PDT),
wrote:

>I'm using a dbx active crossover feeding a couple old adcom amps.
>I've rigged it all to go on and off controlled by my "pre-amp" power.
>But I get a substantual power on and off pop from both amps. It is
>the active crossover causing it because if I leave it out of the
>system I don't have a problem. Probably because the crossover is
>professional gear and not designed to be powered on and off while in
>use. I solved the power on pop by adding a delay to the amp turn
>ons. I already had an electronic switch on the amps because the
>preamp can't supply that kind of power from it's switched output. But
>I still have the power off problem and playing games with the power on/
>off sequence is getting complicated. Any solutions? Or add on
>circuits?

The brute force approach is probably best here:
Switch the speakers, not the individual stages.
You'd need a relay with a turn-on delay but an
immediate turn-off. I've seen this used
internally in power amps ("back in the day", at
least).

The only way this would fail to solve the problem
is if your speakers normally have DC applied to
them... which is a far worse problem that would
need correction first.

Best regards,


Bob Masta

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