DJGold

djdrdisco

I had a folded horn subwoofer that just didn't sound good with my high range speakers. Truth was, all folded horns that attenuate the high end naturally, also DELAY the bass response. Bad Bad. The distance of my Earthquakes' front surface was 8 feet (!) behind the front of the cabinet, if you unfold it.
This creates unnatural delays in the bass response relative to all the other sound coming out of the mid and high speakers. Just listen, and you will hear it.....Tinkle Tinkle.........Whoosh! The highs come out first, then the really lows from the subs come out late.

I tried to compensate for this, by running the preamp feed to the mid and high speakers through a digital delay. As I cranked the delay higher, I could hear the bass coming into sync with the high end gear. It was about just 20 milliseconds difference according to the delay indicator, but it was enough to make a really big difference.

Then, the engineer that I am, I ran the delay FURTHER. Quite quickly, I found myself in the place where Michael Jackson likes to go with his recordings: slip tracks. That's when you move the drum tracks ahead of where they originally were, in his case, usually 30 ms. It started to create an excitement in the music! As a drummer, I knew what was happening. When a drummer is excited, he rides the edge of the beat, rather than right on. Try it, and you will be amazed! Otherwise, there is no beating the physics of phase coherence in a subwoofer that has a folded horn design. The only problem I had was hearing all my headphone mixes right off the board slightly early from what was going on outside my head.

dokai

I've owned CV Earthquakes (a pair of the original L36-PE) and still have a pair of LAB-12 horn subs. I've always compensated for the delay, but never knew about the "slip tracks" technique you described. I'll definintely have to give it a try next time I'm running subs. I assume that it'll work on my bass reflex subs, too, as long as I consider that there's less distance involved in a non-horn design. Thanks for the tip!

yourdjbuddy · Posted: Thu Nov 08, 2007 5:14 pm Post subject:

Like you said, the offset in the headphones I think would be my biggest concern here. If you can't hear correctly to beatmatch, aren't you kind of shooting yourself in the foot? Even if it does sound sweet...

djdrdisco

Yeah, it's true that you would have problems with distractions, particularly if you are beat matching. I don't scratch, so much of the incentive is still there for me. Keep in mind that all of the things in your headphone mix are in sync with one another. It would be a matter of isolating the sounds going on around you, which isn't easy.

A better solution to all this is to get some subwoofers that are rolled off in the preamp, and have cones that are right up front. The days of acoustic attenuation of a speaker by mechanical design are getting numbered. The cost of a good electronic crossover is not that expensive, compared to using a digital delay to time align everything.

I have to wonder how many people notice their folded horns are not time aligned. Mebbe we'll create a few more critical listeners with this post.
Doc D