Power off/power on Thump: digital XO and unreliable power

Mike D · « **on:** 3 Apr 2006, 04:50 am »

For the past week, I have had the pleasure of auditioning a Driverack PA digital XO. It is an wonderful unit with one significant flaw: thump at power off/on.

Is there a way to get rid of this thump? This thump could tear my ribbons apart if the power went out. The power goes out briefly about once every third month. Sure, I have fuses on the ribbons, but why risk it?

kfr01 · « **Reply #1 on:** 3 Apr 2006, 05:02 am »

Quote from: Mike D

For the past week, I have had the pleasure of auditioning a Driverack PA digital XO. It is an wonderful unit with one significant flaw: thump at power off/on.

Is there a way to get rid of this thump? This thump could tear my ribbons apart if the power went out. The power goes out briefly about once every third month. Sure, I have fuses on the ribbons, but why risk it?

Battery backup on the XO? (half kidding).

Mike D · « **Reply #2 on:** 3 Apr 2006, 10:58 am »

Can one of you champs help me with this?
This is an excerpt from a post regarding the same subject:

I would strongly suggest you get the preamp fixed/modified to eliminate the turn on thump- this will potentially harm any speaker and certainly overstress the ESL.

The transformer secondary voltage charging the preamp power supply caps can be ramped up slowly through a resistor which can be bypassed by a relay when an appropriate voltage on the caps is achieved, thereby eliminating the thump. Experiment with the resitor value or change the relay (different voltage) to change the relay turn-on time. Most service agents should be able to help with this problem or modification.

Mike D · « **Reply #3 on:** 6 Apr 2006, 07:19 pm »

Kfr01:

Thanks for the idea about the battery back up. I found one at a Radio Shack that was marked down from $50 to $30. It does the trick for safety.

Mike

kfr01 · « **Reply #4 on:** 6 Apr 2006, 07:29 pm »

Quote from: Mike D

Kfr01:

Thanks for the idea about the battery back up. I found one at a Radio Shack that was marked down from $50 to $30. It does the trick for safety.

Mike

Mike:

I'm glad to hear that my half-kidding remark actually worked. I guess if it works for computing equipment, it should work great for audio electronics. And since the crossover doesn't draw much power, it should be able to last through all but the longest power outages.

The one thing I've read about UPS devices is that they are relatively noisy. As long as this noise isn't audible, well, hooray!

gerchin · « **Reply #5 on:** 6 Apr 2006, 11:34 pm »

I use a standard computer UPS to back up power for my digital crossover. Be aware that some equipment is very picky about the waveform on the 60 Hz power. The UPS that I use outputs a sinewave. Cheap units output square waves or "simulated" sinewaves -- exactly what a "simulated" sinewave is I am not certain.