[Mr Peabody]

Hi all, I have a set of Omen Def and have a question about the sound, wondering if it's normal or I have a problem.  I am using a Conrad Johnson CT-6 into two MV60's converted to mono.  The issue I have with the OD is in the bass response, the overall sound is open and airy, very live, the bass is there just not strong more of in the background.  I am using Siltech MXT Pro New Yorker cables.  To me the bass does not keep up with the rest of the response and with Pop or R&B much bass is just missing or thin.  I've also had a set of Dynaudio and various Klipsch hooked up to the same system and this issue was not there.  If I can't correct this I can give some one a good deal on the OD and matching center.  It should also be noted that my OD are supposed to have Superfly drivers.  I say supposed to because I can't tell the difference by looking at them.  I have tried firing them straight and with tilt in with not much difference in the bass, slightly better tilted in.  I don't have a lot of options for placement so corners or closer to the wall I can't really do.  My spikes do have the cabinets some higher than the recommended 1/4 inches.  Your response would be greatly appreciated.

[Steidl Guitars]

I don't have a lot of options for placement so corners or closer to the wall I can't really do.  My spikes do have the cabinets some higher than the recommended 1/4 inches. 

I was helping a friend set up a pair of Omens the other day.  Two things that helped markedly with the bass was moving them closer to the front wall and into the corner, and placing the speaker on a hard surface rather than carpet.  I'd say the Omens need those reinforcements to help make bass. 

I'd guess that having the speakers raised beyond 1/4" is costing you bass...  can you try lower them, at least as an experiment? 

[morganc]

There are four possibilities that I can see to explain your situation:
1.  Placement:
2.  Height of speakers off of the floor/surface underneath the speakers
3.  Your pre/amp combo
4.  Your room.

I have the Omen Def's and when paired with the right amp, I could hold a concert in my apartment....plenty of bass, amazing dynamics, tone, soundstage....not so detailed, but that is ok with me.....the best bass I have heard is with a Pass Labs XA30.5 and Coincident Frankenstein 300's. I do know that the placement is very important for the OD's, much more so than the Supefly's.   BTW, my OD's have the upgraded driver also.....

I would recommend calling the Zu guys to discuss your needs.....I did this last week and Sean spent at least 30 minutes on the phone with me to discuss how to improve my system......

Good luck and keep us updated.

[richidoo]

Make sure the speaker cable connections are tight.

http://static.zuaudio.com/docs/OmenDefSpecsCW.pdf

The FR curve and impedance curve suggest that it should have pretty good bass response, down to 50Hz with an impedance dip at 40Hz. The tube amp should have no problem with the load.

If that pyramid thing in the bottom of the interior is some kind of horn/port, then it could be that the gap to the floor is critical if it is being used as a resistance port. If it suggests 1/4" gap then try that and see if you get the bass.

In the spec sheet, they mention putting optional resistor in parallel across speaker lugs to change the nominal impedance from 6 ohms down to 4 ohms. What's that all about?
Thanks
Rich

[morganc]

Rich you are correct, the port at the bottom is critical.  I am far from an expert in the science of sound, but by changing the height of the port, the bass response will definitely change.  I have mine tilted upwards with maybe 3/8" in the rear and 1/2" in the front, but I have not adjusted it much of late. 

[Racer X]

Mr.Peabody
You didn't say how many hours are on your Speakers. Zus require a long break in, around 400 hours. I have Soul superflys and had the exact symptoms you describe, my speakers were a inch and quarter in the front, and three quarters in the rear, on carpet. I read a while ago that if you had hardwood or tile floors the bass seemed better, tonight I went to home depot and bought two 16 in tiles lowered the speakers to a quarter inch the rear and a half inch, In the front and magically better bass. Good luck.

[djbnh]

I have Omen Defs and have no bass issues in my room w/my gear (Odyssey Extreme Mono amps / Tempest preamp). They did take me a while to get dialed in: toe-in, distance from back / side wall, and front-to-rear angle. Small changes in things made big changes in sound. I also have a tile under each OD. Ditto the burn-in comments. Rich, nice catch re: resistor, hadn't noticed that: "4 ohm with 10 ohm parallel loading resistor (option, simple in-room binding post install)".

[richidoo]

Good point by RacerX, the speakers will change a lot as they break in. Bass extension can be horrible at first.

I know it's off topic, but I can't find any good reason to put a resistor across the speaker posts. It only lowers impedance which reduces amplifier headroom. It does not increase loudness because it is a load that does not make sound, only heat. Can somebody edumacate me on the wizdumb of the 10 ohm parallel resistor? Maybe check what the manual says about it?
Thanks!
Rich

[Poultrygeist]

Those bottom finger ports are tricky and your carpet may be eating some bass. Try a slab of granite under them.

[Poultrygeist]

You should also lay them on their side to make sure the big foam cone inside has not shifted and is now blocking all the ports. You can look inside the ports with a flashlight and move the cone as needed.

I do feel my standard Omens excell in bass response.

[skite30]

I have a pair of def's and have also felt they are a bit lacking in their bass response. I followed the forums advice and lowered them to a quarter of an inch clearance and must say that has really helped the bass. I laid them down to look at the ports and on one speaker one of the ports is completely blocked and on the other speaker one is partially blocked. So far i have been unable to move the cone it seems to be either glued or stuck any ideas or advice. I texted sean about any easy upgrades and he said to replace the cap with a mundorf silver in oil cap 1.0 value followed by a 10 ohm resistor. He also said black hole 5 applied to the sides covering about 2/3 of the cabinet is a nice tweak.

[Steidl Guitars]

I laid them down to look at the ports and on one speaker one of the ports is completely blocked and on the other speaker one is partially blocked. So far i have been unable to move the cone it seems to be either glued or stuck any ideas or advice.

If the ports are blocked, the speaker can't be working as designed, notably cutting off the bass response.  I'd let the guys at Zu know.  Then, you'll need to move the part that's blocking them, and reattach it in the proper location.  Access would be gained by removing a driver...

[skite30]

I was afraid that I would have to pull out a driver to do it but was hoping someone knew how to do it without resorting to that.

[Sam-fi]

I would really agree with the granite solution, it not only increased the amount of bass but made it cleaner too. I have carpet floors.

One thing that hasn't been mentioned is that an amp with a low (or zero) dampening factor will also increase the bottom end presence.




PS. I checked my bottom ports in a panic after reading your comments. I'm safe - pfeeew