power on/off pop problem

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

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.

t

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.

G=B2

But

n/

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.

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
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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?

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 DAQARTA v4.51 Data AcQuisition And Real-Time Analysis

Scope, Spectrum, Spectrogram, Sound Level Meter FREE Signal Generator Science with your sound card!

Yea, I was sorta starting to lean that way. I found these on fleabay that incorporate a 3 second start up delay. two of them would be cheap. Only trouble is getting the right ac voltage. The adcom transformers are a bit higher. Hate to add a transformer.