Dbx 3bx pops

Hi People, i rarely ask in the forum, but this problem is driving me kinda crazy. I have a 3bx ds dynamic range expander that i use with my turntable and, only with certain albums and certain songs, it makes a poping sound. The "pop" sound always happens in the same part of a song, so it's not random, and it depends on how much expansion or impact restoration i have dialed. Could it be that the dbx is making my amp clip? (i have a cambridge axr 85 amp). The popping sound is so loud that it scares me everytime...but it only happens if im using the dbx. 

In this video you can clearly hear it after the part that says "New York times"



IMHO, that sounds like a bad cap in the DBX unit.  I don't think you're clipping anything.

If it’s been serviced, I’d be surprised if they didn’t catch a bad cap? How long after you turn it on, does it pop?

Also, the DBX unit is right under the table. Have you tried moving it further away? Maybe the cartridge is picking something up from the unit?

I’ve listen to the pop several times now. It sure sounds like a static discharge to me. It builds up and then releases as a pop. It sounds like a Zerostat gun?

When an amp clips, it cuts the top of the waveform off.  Here is an example of amp clipping:


Much different sound than your pop.

Hello mofimadness. The pop only occurs in a specific part of a song, and always on the same part. I can put the stylus in that section of the song, and it will pop every time in that specific part. I tried with other albums, and it's the same, so it's not the LP.  You are right, it sounds like a discharge to me as well, but I think if that was the case, the pop would be random. 

I assume it happens when you turn "up" the DBX and not down?  If so, it's adding something that's overloading or causing a ground/static discharge.  Those DBX units are notorious for noise and "pumping and breathing".   I was a DBX dealer for awhile.  Sorry, but never a fan.

I still think it might be a cap that's leaking and can't hold a charge...



Why don't you  remove the DBX unit, and see how it sounds. I've recently got the best cartridge/tonearm lashup II've tried with this turntable, and I'm hearing the least surface noise, yet the cleanest LP sound I've ever had. It would never occur to me to use a DBX unit in my situation.

Turntable is a 50+ year old Garrard 401, arm is old as well, a Dynavector 501. Not a great deal of moey involved, just a great deal of DIY.

Hope you get it figured out, good luck,


Exactly, when i turn up the expansion level, the "popping" starts. In some cases, like in this album, i cant turn the knob even a millimiter without popping, so i assume its related with the frequencies of the song. I will check again if all the caps are ok just in case, but this problem im having its in fact really weird.

Hi islandmandan, how are you doing? I know this is kinda taboo to say in the audiophile world, but i really like the effect that dbx provides. It makes the music more "spacious". Although, it is true that without the dbx in the chain, my system doesnt have any problems hahaha.

These days, I'm getting maybe a mite more listening pleasure from my analog front end than from digital. Analog has a bit different sound than digital does, but I'm now 76 years old, so I guess I'm due, 'ya know?

Enjoy regards,