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-   -   Is my Receiver my weak link when it comes to Bass? (https://www.avsforum.com/forum/90-receivers-amps-processors/1877161-my-receiver-my-weak-link-when-comes-bass.html)

Andoskyy 02-02-2015 11:03 AM

Is my Receiver my weak link when it comes to Bass?
 
Hi All,

Thank you in advance for any input you have.

I've spent a lot of time building my home theater. My equipment is as follows:

Mitsubishi 73" DLP built in-wall
Klipsch RF-7 Towers (Crossed over at 60hz)
Klipsch RC-7 Center (Crossed over at 80hz)
SVS SB Rears (Crossed over at 80hz)
(2) SVS PB12-NSD's
Denon AVR2112CI

I have almost never been impressed with the bass of the system. The room is completely treated with acoustic panels (Though placement may not be perfect). I'll occasionally get some LFE action, but its few and far between. There's is also not a lot of in your chest punch, and in order to get impressive bass, I have to be really pushing the system.

Went to a friend's house this weekend who has an HSU VTF-1 MK2. Single 10" down firing sub...and it BLEW MY SETUP AWAY!

He has some high quality in walls, but on paper, I feel mine should be at a different level.

I am on a concrete basement, while he is on a main living room floor. His room is a bit smaller, but not drastic. I have consulted with SVS, worked on placement, phase, co-location, etc. No drastic improvement yet.

The only piece of equipment that is leaps and bounds better than mine is his receiver. Probably in the ballpark of a ~$1,500 Pioneer Elite.

I do feel like my receiver is my weak link, but the AVR2112CI got great reviews. Will stepping up to a $1k+ receiver make some difference, or am I better off getting someone in to measure in-room frequency responses?

Thanks!

Andrew

eljaycanuck 02-02-2015 11:08 AM

A couple of thoughts:
- You've got nulls at the main listening position (MLP) and/or your friend's got peaks at his MLP.
- Your friend's suspended floor provides tactile sensation that concrete won't.

Have you measured your room at all (using an SPL meter or an OmniMic or REW + a mic)?

Have you tried putting one sub into your friend's room, or his sub into yours to compare?

stikle 02-02-2015 11:21 AM

That's really odd...I currently have two PB10-NSDs and it's more than enough for my room. Even when I just had one it beat every other home theater that I'd heard to date, including my own (pre-upgrade). And this was on my older $600 TX-NR708.

I have my doubts that replacing the receiver will automatically fix the problem, as in my experience SVS subs are definitely not the problem.

I'm on a wood subfloor, not concrete, so that's a major difference between our rooms.

Any chance you're in the Portland, OR area?

kaiforce 02-02-2015 11:23 AM

Quote:

Originally Posted by eljaycanuck (Post 31401137)
REW + a mic

+1

You will be able to see exactly what is wrong in a graph.

FMW 02-02-2015 11:24 AM

My wild guess is that you have overtreated your room. If not then your expectations may be inappropriate.

Andoskyy 02-02-2015 11:43 AM

Overtreatment is quite possible.

I have not run REW, tried to a while ago, but was over my head. In discussions with someone who does it for a profession.

I'm located in Massachusetts. If anyone is experienced with REW and wants to earn a few bucks, let me know!

No, I have not tried swapping subs, not that easy to do with 80lb subwoofers.

Thanks, definitely giving me something to think about.

smcmillan2 02-02-2015 11:50 AM

Have you run Audyssey and what is the sub trim level on the 2112Ci?

Many feel underwhelmed with the sub setting Audyssey starts with, you may simply need to bump that up a few db...

Selden Ball 02-02-2015 11:52 AM

I don't seem to see a mention of a "sub crawl" having been done. That's one way to try to find better locations for subs. Note that you'd be looking for good bass, not loud bass.

"Punchy" bass often means that one or a few frequencies are being exaggerated because the room's modes are being excited. That is another way of saying that the three frequencies which correspond to the room's dimensions are getting most of the bass power because you've put the sub(s) in a corner. At the center of a wall or 1/4 of the way along it usually is a good starting place. Of course, irregularly shaped rooms are harder to optimize and are where a tool like OmniMic or REW can help a lot.

JHAz 02-02-2015 12:08 PM

The advice above is spot on. just my 2 cents. Almost certainly your problem is not the receiver. all the bass power comes from the sub's amp. Even at 2 volts output (the high end for a consumer preamp output level), into a low 500 ohm input impedance in the subs you are looking at less than one hundredth of a watt coming from the receiver to the subs. There's just about no chance that the sub outputs of different receivers make a significant difference.

Calibration can make a difference. Careful sub placement and integration can make a difference (sometimes simply reversing polarity, sometimes a different location, sometimes a distance tweak.) Sometimes, especially for those who listen well below movie reference levels (an increasingly uncertain concept but still moderately useful) the issue is human hearing - the equal loudness curves essentially provide that if you turn the overall sound down to half as loud, most of the bass region will seem somewhere around one fourth as loud, to the ears of a human being . . . . Then, especially, simply turning up the subs (or engaging a loudness control like Audyssey's DEQ) can fix the problem. BUt if setup is wrong and the subs are fighting each other, or fighting the room at your listening position, EQ will make little difference.

CherylJosie 02-02-2015 12:27 PM

Your receiver includes Audyssey MultEQ-XT. That is one step below the best consumer-grade room EQ that Audyssey provides. It equalizes the subwoofer speaker output frequency response.

Perhaps it is time to review whether/how you are using your room EQ. Details?

I found a significant advantage in bass response using MultEQ over nothing. MultEQ-XT-32 of my replacement receiver sounds even better.

Something else to consider is that bass is not necessarily supposed to leap out at you all the time. If it does, that is a sign that the system is tuned improperly. You might actually have superior performance than your friend does. Actually I would suspect you do simply because both of your subwoofers are more capable than the one your friend has.

The VTF-1 MK2 is rated at 200W with -3dB extension to 25Hz or 32Hz depending on port tuning. Your PB12s are both rated to below 20Hz and more than twice as powerful as well as probably more efficient (larger) drivers and should destroy that Hsu.

I know that when I changed from a single sub similar to the VTF-1 and got dual PB10s, the bass seemed to lose some slam and took on a deep rumbly quality previously absent. In many ways it was more subtle and less 'in your chest' punchy.

Your friend may also be running his subwoofer super hot with manual post-cal level adjustment. His method of EQ might also be different.

I would suspect the tuning of the systems more than the receiver itself, unless your friend has some unique function in his receiver that optimizes that little sub of his to an extreme.

It might also just be difficult to get good bass in your room due to room dimensions and placement constraints, although with two PB12s you should not have any issues... can you disclose your 3 room dimensions, whether there are any penetrations or open walls to other rooms, and the placement of your sub and seating?

Final thing to consider, can you disclose how the bass in your room changes with subwoofer positioning, and where you currently place them? Is there a variation in distance between the listening position and each of the two subs? Are they placed symmetrically in a symmetrical room? Corners, edges, nearfield? Co-located? All this information can help out diagnosing the problem.

Andoskyy 02-02-2015 01:10 PM

1 Attachment(s)
ok, this is a terrible diagram, but created quickly.

red is the TV and everything else is labeled. the blue circles are where I have tried sub placement before. The subs are now directly under the TV co-located. I did notice an increase in output when I co-located, but same overall problems exist.

the side area is 12x10 and the main theater area is 14x22. all 7 foot ceilings.

I have run the Audyssey and it sets my subs at -8 or so...making bass completely non existent. It also sets all my speakers to large, which I understand is a common issue.

I agree that my friend's bass was a little much, but watched a tank battle of Fury and you felt every gunshot in your chest. It felt right :) I feel almost none of that with my system.

Richard Cohen 02-02-2015 01:27 PM

It is not your receiver. Move Sub 1 to the rear left area of your room and hook it up temporarily with a cable you run on the floor. Move Sub 2 to the right wall about 1/3 along the wall. Do a quick level match and do not run Audyssey. Listen for a while and note changes you hear based on placement. Make sure your speakers are set to small with an 80 hz crossover.

Now run Audyssey and see if you hear improvement in the sound. I believe your problem is the initial location of your subs.

chashint 02-02-2015 03:03 PM

In addition to the recommendations already stated.
I recommend turning the volume on the subs down until audessey sets the sub channel trim closer to 0dB vs -8dB.
If the AVR only has one sub trim set each sub volume separately so the AVR sets each sub to the same trim level.
0dB (-3dB) is the target I would go for.
Keep the mic in the same position.

Andoskyy 02-02-2015 03:03 PM

Thanks Richard, I will try this out. Just need to get a subwoofer cable long enough to try it. Will report back towards the end of the week.

CherylJosie 02-03-2015 12:15 PM

Quote:

Originally Posted by chashint (Post 31407761)
In addition to the recommendations already stated.
I recommend turning the volume on the subs down until audessey sets the sub channel trim closer to 0dB vs -8dB.
If the AVR only has one sub trim set each sub volume separately so the AVR sets each sub to the same trim level.
0dB (-3dB) is the target I would go for.
Keep the mic in the same position.

Andoskyy, it might also be helpful to try walking around the room with lively bass playing before you change anything, to see if you can tell if the bass is substantially better in some parts of the room than in others with your current setup. That might help you get a feel for what you need to do with the placement. If you hear a substantial or dramatic frequency nonlinearity at the sofa compared to other places in the room, you know immediately that your sofa is sitting in the middle of a big fat null or two. In my room I have such situation and had to move my sofa a little forward from my living room wall to fix the problem because I have virtually zero placement flexibility for my subs.

Using two identically configured subs will get you between 3dB and 6dB extra bass gain over one sub, 3dB from the doubling of amplifier power, plus up to another 3dB more for the doubling of driver surface area but only for any frequency where the wavelength is 4 or more times the distance between the subs.

With two subwoofers tightly co-located as shown in your diagram, all bass frequencies gain 6dB, but with the subs widely separated, only the deeper bass gets the full 6dB of gain and the shorter wavelength bass only gets 3dB of gain. This separation of gain factors for differing frequencies actually works to your advantage because room mode nulls tend to interfere more with the mid and deep bass anyway.

Probably you already have 6dB max theoretical gain boost over all bass frequencies with the subs co-located like your diagram shows, explaining why the output level seemed to increase with that placement. The boost in output did not improve the situation for you because the room modes that are stimulated by co-located subs are identical. Whatever frequency response issues exist with one sub in that location do not change at all with two subs in that location.

Usually with multiple subs, they would only be co-located in a large venue such as a concert hall where raw sonic power is more important than frequency response due to room modes (the room modes are very low frequency or nonexistent in a large/outdoor venue). In a home theater it is probably better to split the subs up because room modes in a smaller room tend to dominate the subwoofer response. Placing the subs in locations where they stimulate different room modes tends to even out the response.

I have no idea what your level of education is on this topic. Just in case this explanation is not quite clear to you, I believe what is intended by chashint is to level-match the subwoofers to each other and also to level-match the combined sub output to reference, once the subs are separated from each other.

The -3dB final receiver output trim requested is per subwoofer, with each sub used separately, so that the final receiver output trim with both subs used together comes out close to the suggested target of 0dB receiver output trim setting.

As long as the receiver trim does not peg at +/-12dB (or whatever the max adjustment range is) on the receiver's sub channel, you should be OK, but having the trim at 0dB allows you maximum flexibility in your ability to gain up or down with your temporary sub output level adjust in the receiver controls with your remote, as required for any given program/circumstance. The adjustment range of the temporary trim is limited to the same range as the level cal trim because it uses the same electrical attenuator. That is why your sub (and center, for that matter) temporary trims come out non-zero and change with every cal (as well as resetting to initial cal trim level with every power cycle of the receiver), so you want to set the input attenuators on the subs such that the receiver will initially cal the sub out trim close to zero if possible.

Once you have the subs properly positioned for loud and smooth response, the gain at the MLP might reflect the elimination of a big null that you are finding objectionable, and (especially with the suggested nearfield placement) the resulting new gain be enough to max out the trim in the receiver, so turning down the gain on each sub a little is probably a good idea.

If you try doing two simple room calibrations (do two '3 position calibrations'), with one subwoofer at a time turned on at e.g. AC input for each cal (but both subs connected to receiver sub out and both sub input gains set to 50%), you can record the final sub level cal for each sub and tell how well the output level of each one matches reference with its individual input attenuator set to mid-gain. Leave the microphone in the sweet spot for all 6 total 'positions'.

With that info then you can approximately adjust the subs individually on their input trims so that they level-match to each other and to reference -3dB, then the final post-cal with both on should be nearly 0dB at the final receiver output trim.

Level-matching subs that are in radically different placements is probably a good idea, to smooth out the overall response, even if one sub ends up working harder than the other. You have power to burn with those subs in that room and should not need to gain-match (as opposed to level-match) them, but in the extreme case where one gain control is turned up much more than the other, it is conceivable one sub could begin distorting early during a heavy-duty listening session, so use reason when level-matching. Probably not an issue for you.

Another tip is to try to keep the distance between sub and sweet spot matched so that the delay of each sub output is the same at the MLP. Then you avoid phase cancellation due to placement and do not need to adjust the delay independently at the subs (not really possible with the analog subs you are using anyway since they lack digital delay line and cannot add a straight delay term, only a frequency-dependent one).

Hope this info helps without confusing you. I tend to give too much information in the expectation that more education is usually better than less, and assuming that I actually understand what I am discussing as well as communicating clearly (not necessarily a given!).;)

Andoskyy 02-04-2015 02:04 PM

Thanks again everyone. Great posts with a lot of information. Back from work travels on friday and looking forward to testing out some new subwoofer positioning, as I now think that's my biggest problem.

As someone mentioned, i've likely overtreated my room. I made my acoustic panels by hand and got a bit carried away. I have about 17 panels. 7 of them are 2'x4'x4" of mineral wool, and the other 10 are 2'x'18"x3" of normal wall insulation. Seems like this could be cut down a lot by just placing them at the reflection points.

Also, I have a 12x10 section of the basement off to the left of the TV...see the crude diagram above. If I were to curtain off that area with dense curtains during movies, would that reduce my cubic footage, or will a curtain not do much?

Richard Cohen 02-05-2015 10:17 AM

The curtains will not do anything regarding the bass.

Alan P 02-05-2015 11:35 AM

Quote:

Originally Posted by Andoskyy (Post 31404745)
I have run the Audyssey and it sets my subs at -8 or so...making bass completely non existent. It also sets all my speakers to large, which I understand is a common issue.

So, have you turned up the sub trim at all from the -8db where Audyssey set it? If not, bump it up 3-6db and see what you think then. :)

Did you set all speakers to "small"? Where are your crossovers set?

Quote:

Originally Posted by chashint (Post 31407761)
In addition to the recommendations already stated.
I recommend turning the volume on the subs down until audessey sets the sub channel trim closer to 0dB vs -8dB.
If the AVR only has one sub trim set each sub volume separately so the AVR sets each sub to the same trim level.
0dB (-3dB) is the target I would go for.
Keep the mic in the same position.

I don't recommend either of the things bolded above (sorry chashint).

I recommend a sub trim of -8db to -6db. This gives you plenty of room to run the sub hot without going over "0db". This keeps the danger of clipping the subwoofer signal to a minimum.

I'm also a proponent of gain matching your subwoofers, what chashint describes above is level matching.


Below is my standard procedure for setting up dual subs with Audyssey.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Set the gain on both subs to the same level - around 12:00-2:00 on the gain knob is a good starting point (just a starting point, gain structure can vary greatly from one manufacturer to another). Set phase to "0" on both subs for now.

1. Connect sub #1 only and place it at the MLP
2. Do the sub crawl to determine the best position for sub #1
3. Place sub #1 in that position
4. Connect both subs and place sub #2 at the MLP (with sub #1 playing as well)
5. Do the sub crawl to determine the best position for sub #2
6. Place sub #2 in that position
7. Playing the AVRs test tone, adjust phase on one of the subs until you get the maximum SPL at the MLP (could be variable or a simple 0/180 switch) (if you have SubEQ HT, skip this step)
8. Run Audyssey, first mic position only, and "calculate"
9. Look to see where Audyssey has set your sub trim, you want it to be around -6db to -8db ideally
10. Adjust the gain on both subs by the same amount up or down as needed
11. Repeat 8-10 until you get the sub trim around -6db to -8db
12. Run the full Audyssey calibration
13. Set all speakers to "small"
14. Set all crossovers to 80hz (or, if set higher than 80hz by Audyssey, leave them alone)
15. Bump up the sub trim by 3db to 6db to your preference
16. Enjoy!

Hope this helps!

Alan P 02-05-2015 11:37 AM

Quote:

Originally Posted by Andoskyy (Post 31472081)
Thanks again everyone. Great posts with a lot of information. Back from work travels on friday and looking forward to testing out some new subwoofer positioning, as I now think that's my biggest problem.

As someone mentioned, i've likely overtreated my room. I made my acoustic panels by hand and got a bit carried away. I have about 17 panels. 7 of them are 2'x4'x4" of mineral wool, and the other 10 are 2'x'18"x3" of normal wall insulation. Seems like this could be cut down a lot by just placing them at the reflection points.

Also, I have a 12x10 section of the basement off to the left of the TV...see the crude diagram above. If I were to curtain off that area with dense curtains during movies, would that reduce my cubic footage, or will a curtain not do much?

As Richard said, the curtains will do nothing for the bass. I also don't think that the treatments you have should be affecting the bass that much.

You should be able to get some great bass with what you got. Try my suggestions above and let me know how it goes.


Just an FYI - treating your room (for bass) without measuring your response first = very bad idea. ;)

chashint 02-05-2015 08:31 PM

Quote:

Originally Posted by Alan P (Post 31501545)
I don't recommend either of the things bolded above (sorry chashint).

That's ok by me, your opinion (which is a valid way to set up subs) does not change my opinion (which is also a valid way to set up subs).
If the OP is interested in learning it's not hard to try both methods and see which is preferred in that specific application.

Alan P 02-06-2015 09:01 AM

^^^^

Care to explain your reasoning behind these two recommendations??

Quote:

I recommend turning the volume on the subs down until audessey sets the sub channel trim closer to 0dB vs -8dB.
If the AVR only has one sub trim set each sub volume separately so the AVR sets each sub to the same trim level.

Eyleron 02-06-2015 10:37 AM

A couple thoughts:
  • The room treatments don't appear to be thick enough to affect deep bass much. Then again, the OP seems to be looking for more mid-bass slam. This is 60Hz to 200Hz. So the treatments might be damping too much of that. Or maybe it's good treatment, but requires a commensurate increase in output.
  • And if we're talking about mid-bass slam which includes those higher frequencies, then we are absolutely talking about frequencies that include what the main speakers do above crossover.

There have been some interesting threads in the past year about mid-bass slam.

SBIR plays a big part, because it affects those frequencies in most rooms. There's a big peak, and then a dip in mid-bass!
Moving the front 3 speakers either way out into the room, or closer to the front wall, will move that frequency down or up.
I don't think you (Audessey) can EQ this. More power sent to the dip will only increase the dip. (not minimum phase?)
Lastly, if you're looking for chest cavity stimulation, that requires a dB level like 100+. If the sub and speakers can't do that at your listening position, then you won't be feeling what you'd get at a live concert, etc.

As mentioned above, that can come from peaky or artificially-boosted response in that frequency, but if you care about fidelity, you need the whole system to be able to handle that level.

Legairre 02-06-2015 04:06 PM

Quote:

Originally Posted by Andoskyy (Post 31401961)
Overtreatment is quite possible.

I have not run REW, tried to a while ago, but was over my head. In discussions with someone who does it for a profession.

I'm located in Massachusetts. If anyone is experienced with REW and wants to earn a few bucks, let me know!

No, I have not tried swapping subs, not that easy to do with 80lb subwoofers.

Thanks, definitely giving me something to think about.

Where are you at in Mass? I'm in CT and would be happy to come up for free and help with REW ,take measurements, play with placement, get them dialed in, etc... As long as you're not too far into Mass.

Andoskyy 02-08-2015 07:06 AM

well...this was an annoying process! I did the sub crawl with both subs. Found good locations, though didn't notice huge changes doing the sub crawl like i thought I would.

Anyway...as soon as I moved the second sub to its final location in order to level match with the test tones and my SPL meter, i'm getting a steady hum from one of the subwoofers that I cant get rid of. Tried plugging it in everywhere...with other components, without other components, with an extension cord in another room, etc. I'm only running the DVD player currently, so no ground loop issue with the cable connection. I have a total of 5 subwoofer cables of different lengths and have tried them all...hum persists with all of them.

So....all this to be continued until after I fix the hum.

Andoskyy 02-15-2015 11:59 AM

Well it was a bad amp giving me the hum. Spent some time on the phone with SVS and that was the culprit. New amp en route!

Andoskyy 02-15-2015 12:00 PM

And also upgraded my receiver to a Denon AVR 4520CI. Accessories4less had a deal I couldnt pass up!

Looking forward to get everything hooked up to take advantage of Audyssey x32 and Sub EQ


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