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Discussion Starter #1
I have learned a great deal about this hobby in the 3 years since I put together my current system. There's a few gaps still, but most of my understanding is fairly solid. Don't know why I never re-checked my original setup, but I decided to pull out the RatShack meter and revisit my receiver setup and found some interesting surprises. Of those, the one I can't get past is the sub level. The main channels are balanced to 75db at reference volume just fine, but I'm getting readings of around 85-87db on the RatShack after I just turned down both the volume on the sub and the channel level in the receiver considerably. Now, I know that I've been running my sub very hot the last 3 years, and for 2 of those I've been turning the level down for movies then turning them back up. With the new adjusutments I've made the bass sounds very integrated and restrained for all listening modes. With cd's it seems like there is no bass at all at lower volumes. I realize that particular sensation will pass once I've adjusted, but I simply can't get over the fact that the sub level is still reading over 10db too hot. I even cranked a few movies and the sub never sounded distressed. The room is small and oddly shaped, with an uncommonly low 41hz first axial peak. But how can I still be 10db hot when my ears say there's no bass? Am I missing something here? BTW, I am very certain that I am taking the RatShack measurments properly. Not really a technical question, but I'd like your opinions on this. It'll help me sleep better. :D
 

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I'm not surprised. When I first got my HSU TN1220HO subs, I set them up by ear to "sound right". I checked the calibration later and found it 14dB too hot! I later moved both of them to the same corner and had to dial it down another 10dB to get the proper SPL (I suspect a room mode is excited more with both in that corner... a BFD is likely in my future).


Bass is damn hard to do by ear. FWIW, when listening to music, a properly blended subwoofer sounds like no subwoofer at all. Only if you turn the sub off should you notice something missing. When you have it set like that, you are dialed in perfect, at least in my experience.


Sorny
 

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I think you got used to being able to 'hear' the sub, and notice it. If you think of it a part of your speaker, no driver should really call attention to itself, in this case your sub. A well blended sub will not call attention to itself, but provide the bass that your speakers do not. If you turn the sub off as Sorny stated you will notice that the sub is missing. :)
 

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Quote:
The room is small and oddly shaped, with an uncommonly low 41hz first axial peak. But how can I still be 10db hot when my ears say there's no bass?
Because you are calibrating to the 41 Hz peak leaving the other bass frequencies under represented. You could use a BFD or something similiar to bring it down and recalibrate. You will be amazed at how much better it sounds and integrates.


DJ
 

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Discussion Starter #5
Untrue actually. The sub is an Infinity Interlude IL120s, which features their RABOS parametric EQ technology. I've chopped off over 10db of the axial peak. It's still there, but pretty modest. I suppose I should've mentioned that first. All channels are set to small, bass output set to subwoofer only, and according to my test readings the proper setup for my setup is pretty much to unplug it! The final calibration of the RABOS setup procedure agreed, when it runs some tracks intended to use the RABOs meter to match the sub with the mains as far as level is concerned. It becaome right when the sub's volume control hit '0'. It's almost as if the receiver is allow low bass to the mains, which play flat to 38hz. But there IS a very noticable difference between setting the channels to large and small, so the system is working. Bizzare, huh?
 

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Quote:
I suppose I should've mentioned that first
Yes, I should say so. Dr. Spike's explanation seems to make the most sense then. That and the 120 really peters out below 30 Hz.


Do your speakers have built-in powered subs? I've seen situations where they have been turned up too high and the distortion in those drivers have caused meter anomalies.

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Bizzare, huh?
Indeed.
 

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Discussion Starter #7
No, the setup is all Infinity, and the fronts are non-powered tower IL40s. The 120s is rated to 28hz -3db, and I found through my own measurments that it is down 4db at 20hz. The small room is undoubtedly helping the 120s out there, since others have complained of it's weak response in the 20's. Spike is correct in that I'm just used to hearing the sub draw attention to itself. I do understand that, and in time it'll probably get dropped again closer to what the "right" level is. The numbers, though, tell me that my sub is not needed at all for bass reproduction in music with the front speakers set to small, which just isn't right. I'm starting to suspect the receiver's bass management is at fault. A while back I had similar issues regarding cascading crossovers.... i.e. using the sub's internal crossover instead of turning it off (or up as high as possible). Although using it was "incorrect", I found the bass to be unacceptable in terms of quality and the sub was localizing when I defeated it's internal crossover. I can't find figures to confirm it, but I think the receiver is only using a 2nd order 12db low pass slope for the LP crossover, which would make the HP only 6db 1st order if I'm not mistaken. At a crossover point of 80hz I think a 4th order slope is necessary to sound right IMO. So I'm left with buying a new receiver to fix my woes. I know the thread sounds kind of worthless, but I just enjoy talking with other people on the forum. Like I said, it'll help me sleep better at night as I tend to be a bit obsessive. :)
 

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I was thinking after I posted yesterday that maybe someone accidently flipped the RABOS filter to "off", but I'm sure you probably checked that. I used a 120 in between DIY subs and my girls used to love to fiddle with the switches in back.


The crossover was the only other thing I could think of too, but I assumed everyone was using 4th order LP in receivers nowdays. Maybe you can borrow another receiver to confirm. Maybe even the DSP chip that handles BM is on the outs.


Don't feel like it's a worthless thread because those pesky little problems get us thinking about things we usually take for granted.
 

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Discussion Starter #9
Well, when I upgrade I like to really upgrade, so buying a new receiver will not be a cheap endeavor for me. The rec is a Denon AVR-2800, and I feel it is the weakest link in the system by far (aside from the room itself of course). This and also the 2801 I believe do not allow for adjustable LP crossover settings. It is locked at what the worthless owner's manual describes as "around 80hz." Why in the world Denon would be ambiguous is beyond me, it's either 80hz or it's not 80hz. I know enough about crossover slopes to realize that it must be a 2nd order LP, since the sub is reaching up there in freqs with it's internal LP turned off. Figuring with an 80hz 2nd order slope: 160hz = -12db........... 320hz = -24db ........ etc. The LFE hits it's brick wall at 120hz, but the bass summed from the mains and surrounds will allow for audible output levels at 320hz and beyond with this setup. If the Denon had a 4th order slope I'm sure it would sound right. The DSP is something I never thought about. It sometimes requires re-selecting the surround mode several times to get it to lock into the mode and sound right. I often use Matrix DSP on the Denon to make up for the room with CD listening and it just sounds odd sometimes. Cycling the surround modes a couple of times makes it right. Perhaps it's just going on the fritz? I'm pondering either moving up to a new Denon 3805, or going a bit upmarket brandwise..... possibly Rotel. If you look at my post info though you can see I live in the boondocks, so a drive to a Rotel dealer would have to be a vacation in and of itself. If anybody has any brand suggestion to go with some Infinity Interludes then let em' fly. Something similar to the Denon without the thin midrange and a bit smoother high end. Thanks guys, so far, for replying. I figured I'd get ignored for rambling too much. :D
 

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Nothing wrong with some rambling now and then. :D


It could very well be the BM on the receiver or a setting that isn't quite right on it. Hard to tell really.


Lot's of good brands out there. All depends on budget and what you are looking for. :)
 

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Discussion Starter #11
Fine tuning over the last week has produced a much different sounding system than what it was before. I've been helping a younger cousin set up his first system, and it inspired me to work on my own again finally. On the one hand, the sweet spot has widened and I hear more detail throughout. On the other, the whole sound seems a bit more flat than it used to be. Not referring to bass though, just the whole sound in it's entirety doesn't sound as involving as it used to. I think I may have had some minor level and time delay settings that were giving me a nice reverb effect that I'd gotten used to and liked. Additional listening is ovbiously required to adjust. Later on, I will re-evaluate my sub levels again. The 120s seems much more happy at this level than it was before.... it speaks with greater refinement now. As for brands, I have yet to discover all my options. Budget is hanging anywhere from $1000 to maybe $1500. I'm not interested in separates now, mostly because I've barely got room for the equipment that's already in the room now. The reason I gravitate towards another Denon is I have a somewhat decent chance of talking a friend into getting me one off his employee discount, which is basically store cost. That's a value equation that can't be argued with. I've been told that Rotel has a warmer sound that would compliment slightly bright speakers such as the Infinitys well, so I threw that into consideration. But is it worth the greater cost I wonder? I wanted to gain some headroom in the process as well, and I'm quite confident that 75 Rotel watts per channel would stand toe-to-toe with 120 Denon watts per channel any day of the week. Do you guys think Rotel is a a good performance brand for it's price, or is it over-priced for it's performance?
 
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