STF-2 issue - no mid-bass

[Hagarr]

Here is my current setup -
Denon 1909
1- STF-2
C- Energy CC-10
L/R - Energy CB-20
LS/RS - Energy CB-5

The sub is performing wonderfully in lower frequencies but there is a huge gap when it comes to mid-range. I have watched Transformers/THX demo/Batman/ name anything. It is all low bass, it just hits you all at once without the midrange. I have run Audyssey and always have to adjust the sub level afterwards. When I ran Audsy I left the subwoofer gain at 12 o'clock. The receiver is set to LFE+Main and the sub crossover is turned to Out. The receiver crossover is set to 110hz.

Do I have a bad cable or is there something wrong with the sub or the settings?

Thanks in advance. Any other details needed?

Brian

[Hagarr]

Yes, there are a few details I missed. LOL

The sub is turned to 'out'.

All other speakers are set to 60hz and are 'Small'. I will change all to 80hz.
I am running MultiEQ.
Thank you hometheatergeek for the link to the test CD. I have been playing with it and have enjoyed the frequencies until I get to the 50-59hz test. The sub falls flat on its face...I hear a frequency but the volume is 1/5th of the previous frequency range (40-49hz). I certainly expect it to sound different but not like this.

Essentially after the 50hz+ range the volume is very low compared to the previous frequencies. I can adjust the volume on the sub and makes those fq's come alive but only with turning it up to nearly max.

I don't have an SPL meter and don't think it is required for such an apparent hole.

Thoughts?

Thanks

Brian

[skool]

How big is your room? Where is your sub located? Please change your crossover to 80 Hz. I doubt your CB-20 has decent bass extension and can handle better midbass from 60-80 Hz compare to your STF-2.

Regarding your comments regarding the sub "falls flat on its face" after 59 Hz, I hope you do realize that this is normal due to the fact that your crossover point is at 60 Hz, which means bass is quickly rolling off at a 24 db/octave following the crossover point. Any bass above 60 hz should be coming from your bookshelves. If you're hearing low bass from your bookshelves, once again, this is probably due to the low bass extension of your CB-20.

Have you considered moving your sub to another location? You may be sitting in null area and thus feeling lack of midbass. Tried moving your sub to another location and rerun Audyssey. Your gain on the STF-2 should be around ~11 o'clock. Any higher gain and you may risk clipping your sub too much.

[mystik610]

When I had the STF-2, I found that it performed very well in the mid-bass section. Are you turning up the sub gain and/or the sub level on the receiver after running audyssey? With a 60hz LPF and crossover point set on the receiver, all the mid-bass is being routed to your fronts, and if the sub is set to higher levels than the fronts, the lower frequencies from the sub would be more pronounced than the mid-bass frequencies coming from the fronts. Those bookshelf speakers might not be able provide enough mid-bass output to match the output of the stf-2 on the lower end. Try placing the STF-2 in the front of the room, and using a 120hz LPF and crossover point.

[Hagarr]

Thanks for the comments guys.

The sub used to perform well in the midbass area. The room is a dedicated media room measuring 14x16 with 10 ft ceiling. The location of the sub has been changed multiple times. Even when I am right next to it the 50hz+ frequencies are minimal.

All speakers are set to 80hz in the receiver. I have already tried a crossover for sub at 120hz = zero change.

skool - I had already changed the crossover to 80hz for all speakers before I ran the test tones and previously had the sub crossover at 100-110. I don't expect too much from the CB-20's and they seem to be performing well. It is at the 50hz frequency is when the sub disappears. I have also tried it just using the crossover in the sub but yields same result.

The sub is currently behind the couch in the back/middle of the room and has 10-12 inches behind the port.

I will try it after church today with Audyssey turned off.

Thanks

Brian

[Pete_Hsu]

Brian,

Have you tried inverting the phase switch on the subwoofer to see if that gives a better transition with the mains?

Does your room open to any other areas of the house, and if so, where is the opening and what are the dimensions of the opening?

Sitting in and/or placing a subwoofer in the middle of the room is problematic for the bass performance due to a null that results from the room's standing waves in that location.

Assuming your room is well-enclosed, try placing the sub in a front well-enclosed corner), and try moving your listening position closer to the back wall.

Also, make sure that your left and right mains are set to 'Small' (with 80Hz crossover), and are not set 'Full Band'. The subwoofer amp should be set with crossover 'Out'.

When you say that your sub used to perform well in the mid-bass area, what placement did you use at that time, and what settings on the receiver?

Thanks

Sincerely,

[Hagarr]

Hi Pete, I have changed the phase to see if it makes a difference = nope.

The room is completely enclosed and insulated. What I meant to say concerning placement is that the sub is located at the rear/center of the room behind the couch and has been placed in each corner of the room. The rear/center of the room has yielded the best result. The rear of the room has a part that is inset that was originally for TV's but my 100" screen would not fit. It measures 90" wide and 20" deep, the sub is in that area. I have crawled around that room more times than I would like to admit. I have also tried a different cable, I wish it were that simple :)

Honestly, my buddy pointed out that there was much more to Transformers (and other movies) than what we were hearing. Sadly he has an inferior sub and he's pointing this out to me. That is when I started doing some tests and now it is driving me nuts! The bass sweep is weak until the low bass hits and then the room shakes.

All speakers are set to 80hz on the Denon 1909.

I have tried the following settings:
1)a)Audyssey enabled - LFE+Main, sub set to "out" = same result
b) Audyssey enabled - LFE, sub set to "in" w/crossover on lowest setting 90hz = same result
2) (same a and b)Audyssey disabled - same result

Yes, I do hear 50hz and above but the volume is so minimal compared to lower frequencies. I have crawled and walked around the room to see if it was positioning and I did hear some difference but nothing noteworthy.

Could there be something wrong with the internals of the sub? After all, it is a machine and from time to time they remind us of that.

Short version = loudness below 50hz and weakness above 50hz regardless of settings on receiver and/or sub.

I am spent. What next?
Thanks

Brian

[Hagarr]

Oh and thank you for taking time out of your Sunday for me.

Brian

[Pete_Hsu]

Thanks for the info Brian. So it looks like you are sitting towards the back of the room, with the subwoofer sitting on it's spiked feet placed sideways directly behind the couch, is that correct?

What is the channel level set at on the receiver for each speaker and for subwoofer? What are the distance settings set at on the receiver for each speaker and for subwoofer?

Note that when you set crossover switch to 'In' on the STF-2, you need to set the crossover knob all the way to the right (ie. 90Hz). If you set it to 30Hz, then the higher bass frequencies get rolled off.

Finally, what did you mean when you said "the sub used to perform well in the midbass area"?

Thanks

[Hagarr]

Yes, I meant 90hz. I edited my previous post.

I have tried the sub in many different locations as well as every possible position. On its back/side/top etc in each local.

I have measured the speaker distances and have found them to be very accurate. The channel level for each speaker is;
L:+4.5 C:+3 R:+4 LS:+3 RS:+3 Sub:-2

I have tried changing the sub channel to the extremes and naturally notice a difference but nothing that resolves the situation. Level on the sub is at the 11 o clock position.

Taking the sub out of the equation I found that the other speakers are performing within their parameters. So my main focus is why I can't get the desired volume from the sub at the noted frequencies.

I don't know if I can qualify the "used to perform" statement. I remember when I got the sub/Ventriloquist a few years ago that it just blew me away since all I had before was some crappy Panny HTIB. A few months ago I first noticed the lack of midbass but I ignored it thinking it was just the track until my buddy pointed it out.

Is there a possibility of simply shipping you the amp to check it out? I would hate to ship the entire box...any local service techs you use in the Houston area?

Brian

[Pete_Hsu]

It doesn't seem that the subwoofer is in need of servicing per se. If there was an issue with the subwoofer amp or driver, then it would be noticeable with deep bass content too.

Right now, the main speakers appear to be running 6db higher in level (!) relative to the subwoofer! That means that the upper bass from the speakers are much higher in level than the mid-bass from the subwoofer. This may not be an issue in the deeper bass because you probably have a lot of room gain to lift up the deep bass response, but this will be an issue in the mid/upper bass where the sub transitions to the mains.

I suggest that you get a Radio Shack SPL meter, a test tone CD with 1/3 octave-spaced frequencies from 25-200Hz, and do some measurements to see what your frequency response looks like. It is difficult to set by ear and trial and error, and much easier to do with this basic device.

Sincerely,

[skool]

You have an interesting problem. Do you think it could be your receiver? Could you possibly bring your STF-2 to your buddy's house and test it on his system to see if it yields the same result? If it is, it may be your STF-2 needing service. If it sounds better or "fuller", then it may be your receiver. Try to isolate the problem before having to ship anything out for service. Good luck!

[Hagarr]

Pete - I thought you were going to say that :) re: SPL meter.
If I turn the sub channel any higher than it overpowers everything else.

I am going to bring STF-2 downstairs to my Panny XR55 and run the same tests.
Time to track down a meter.

Thanks

[Pete_Hsu]

Hi Hagarr,

One thing that could significantly help is use of an equalizer like one of the Behringer units, Antimode 8033, etc. That will flatten out your deep bass response so that things don't sound too deep bass heavy even when you increase subwoofer channel level.

If you have a friend who has an equalizer and/or SPL meter, then maybe you could convince them to try it out at your place?

[Hagarr]

Ok Pete, I have attached a simple Excel file showing the initial results of the SPL meter. I ran the test cd twice. Once without Audyssey and another with. Most of the settings are noted in the file.
Funny how the Audyssey results are nearly 10dB higher yet the channel is set to -8.

I am going to move the sub to a few other locations and go again. This is all performed in the media room.

Brian

[Pete_Hsu]

Thanks Brian, that helps! The SPL that you measured is with the main speakers on, crossed at 80Hz on the receiver, correct?

You can see that the 30-50Hz region is much much higher in level than the 70-90Hz region. This certainly shows why mid/upper bass impact is low relative to deep bass output.

Interesting that Audyssey really doesn't help to flatten out the response. The variation from one frequency to another is as much or higher with Audyssey on vs without.

Try inverting the phase on the STF-2 to see how the measurements look. When measuring with Audyssey off, set crossover switch on the STF-2 to 'Out'.

It will be interesting to see the response of the sub in different locations...

[Hagarr]

Ok, I have spent some more time this evening. Attached file.

Still not even close to happy. How do I reset the receiver to defaults? Denon 1909...Denon manuals suck...may just have to do with a later night and frustration.

Thanks again.

[Pete_Hsu]

The results without Audyssey look a lot better than last time. Now, we need to see 90Hz, 100Hz, 120Hz, 150Hz, 200Hz, etc to see how close in level the subwoofer is compared to the mains...

[hometheatergeek]

Ok, I have spent some more time this evening. Attached file.

Still not even close to happy. How do I reset the receiver to defaults? Denon 1909...Denon manuals suck...may just have to do with a later night and frustration.

Thanks again.

This is what I found to reset the AVR:

1)Turn the power off
2) Press the POWER, INPUT MODE, and SPEAKERS buttons at the same time
3)Once the display starts flashing release the INPUT MODE and SPEAKERS buttons.

This will set the microprocessor in the AVR back to the way it came from the factory. You will lose all of your settings but I quess in this case that's the plan.

Hope this helps.

[Hagarr]

Just wanted to give an update. After taking a break, several days, I did the sub crawl exrcise and found an acceptable location. I don't hear or feel anything below 30hz but everything else is great.
Location location location.
Sigh.
Brian