GWMoody Posted March 22, 2002 Share Posted March 22, 2002 Following my earlier topics I have now sold my Khorns, purchased and installed my Pioneer VSX-49TX, RF-7s, RC-7, RS-7s (4)(except I have 2 RS-3II loaners until my white ones arrive)and a Sunfire sub. The set up system (MACA)for the pioneer works very well but I have a couple of questions which I need help for: 1. MACA sets individual speaker levels and these are then listed as + or - dBs, generally within + or - 2 dBs except the sub which is around - 5.0 dB. (a) Does this mean in reference to the strength of its test signal assumed to be 0 dB?, ( and is the ideal for each speaker and sub to be 0 dB. © There is a feature that allows one to overide the automatic setting. Should I use this to set all outputs to 0 dB? 2. MACA also measures and I believe adjusts the level at different frequencies (equalization), and then shows a plot for each speaker. These are typically + or - 4dB with some odd very high to very low ones. (a) Is this measurement the levle of the output of the speaker in reference to the input being 0 dB?, ( Is the ideal for the level to be the same at each frequency? © The system has a feature to overide the auto setting. Should I use this to bring the level to 0 dB at all frequencies? Quote Link to comment Share on other sites More sharing options...
dougdrake Posted March 22, 2002 Share Posted March 22, 2002 I'll answer the ones I can... 1b) Yes, the ideal would be if they were all at 0, but that would require incredible feats of engineering! 1c) No. Setting them all to 0 will result in the system sounding out of balance. It adjusted them to the levels it did so that at your listening position, all speakers were at the same volume. That allows the surround coding to work properly, and not have your big front speakers overwhelm everything else! 2b) Yes, the ideal would be 0, meaning the speaker was flat -- the same response at every frequency, a speaker designers dream!! It would also require a completely inert room (sound-wise), like an anechoic chamber (not very comfy to sit in, BTW). 2c) This sounds like it has a built-in equalizer. EQs can be used to flatten the response of a speaker, but sometimes at the risk of frying drivers if the EQ is up so high in a frequency band that when the music soars at that frequency it overloads the driver. I'd say no, don't adjust them to 0. Just my .02. Doug ------------------ My System Quote Link to comment Share on other sites More sharing options...
GWMoody Posted March 24, 2002 Author Share Posted March 24, 2002 Thanks for your input dougdrake. That is the most data I have found. The test CD places all appear to be still on 2 channels with the promise of 5.1 soon. 7.1 does not appear to be on the radar screen. After running auto setup, there are two areas where the levels seem to be out of whack: (a) the front RF-7s are -7.5dB and -10.5dB at 63Hz and +6.5 and +8.5 at 125 Hz respectively. Does this mean that my room is eating the bass? and why didn't the set up program reduce the level at 125 Hz?; and ( three of the surrounds are -6, -4.5 and -7.0 at 125Hz or 250Hz. Is it worth trying to pull this up? The recever, by the way will give a EQ GAIN OVER warning if the gain is wound up too much (I haven't touched it yet). According to data provided by Colin in "At what range does voice dialect fall?" we probably cannot detect 3dB or less. One final isue is that the receiver setup system will not drive the sub-woofers in THX mode if any speakers are classified as LARGE. This is not true in music modes. This means that we cannot have bass from 50Hz to 80Hz from the speakers. Is this significant? how much of this do we actually hear? Colin's data suggest 400Hz and above is what we hear but I am sure I can hear a 60Hz hum! Your thoughts will be most welcome. Quote Link to comment Share on other sites More sharing options...
dougdrake Posted March 24, 2002 Share Posted March 24, 2002 Regarding the dips/spikes on your speakers...I'm not sure if you are saying that the Pioneer has moved the channel level for the RS-7s DOWN 7.5 and 10.5db at the freq's you mentioned, or that their output falls by 7.5/10.5 at those freq's. If the Pioneer adjusted the output level down at those freq's, it means that your room, when interacting with the RS-7's, produces a BUMP at those freq's and the Pioneer is trying to flatten it out. If the output (SPL) is down at those freq's, then your room is "eating" the bass. It is not uncommon to have a couple of freq's that spike/dip in a room. I have a bass boost in the 50-70 hz area, myself. Re the sub...are you sure that the receiver doesn't send ANY bass to the sub in THX mode if ANY speaker is set as large, or it just does not send bass to the sub for that speaker that is set to large? It is typical that the receiver's bass mgt will send bass to the sub in all channels set as small. And, yes, you will be missing a lot of bass if you don't get any output in the 50-80hz range -- that is, I believe, where a lot of mid-bass resides. Doug ------------------ My System Quote Link to comment Share on other sites More sharing options...
GWMoody Posted March 24, 2002 Author Share Posted March 24, 2002 Thanks your prompt reponse - don't you ever sleep? Your first question is a source of great potential confusion to me as to whether I am dealing with the cause or the effect: For speaker level the setup produces a list of levels, one for each speaker. Usually in the -4.0 to +4.0 dBs range. I assume that this is the sound level received by the microphone (which I put at the sweet spot) relative to the test sound level generated. Is this correct? Secondly the setup produces a graph of levels at various frequencies for each speaker. I presume that each one is the level of the sound received by the microphone at that frequency for a the given fixed test output level from the amplifier. Is this correct? I also presume that the setup automatically adjusts the gain of the amplifiers for each channel in an attempt to level these outputs. I am saying that the graph shows the fronts 7.5/10.5 down at 63Hz which I understand means the output is down that much at that frequency. So per your response we can conclude that the room is eating the bass. One other symptom that might support this is that when the setup system calculates speaker distances it finds the sub-woofer to be 25' away whereas it is only 14' away. It gets all other distances correct. Re the THX problem, I have not tried all possible permutations but if the fronts are classified as large no bass goes to the sub-woofer from any speaker. Given my bass hole perhaps I should set the sub-woofer crossover at 80Hz and receiver crossover at 50Hz. The overlap should give me the needed boost. If your system gives you a bass boost at the 50 - 70Hz range why don't you reduce your gain in this frequency range? Thanks agains for your input and I look forward to your reply. Quote Link to comment Share on other sites More sharing options...
dougdrake Posted March 25, 2002 Share Posted March 25, 2002 Part of being classified a "No Life" is they take away your sleeping privileges. Have to stay up all night listening to Diana Krall on my wonderful Klipsch's!! I'm just guessing on this, because I'm not familiar with your receiver and how it runs the setup tests. But what you describe makes sense, and I believe you have decoded the mystery correctly. I suspect that the reason your receiver has a hard time properly calculating distance to subwoofer is that bass tones are difficult to measure accurately, without modifications/adjustments to the measuring equipment. Perhaps your system hasn't been designed to handle that. The readings from the famous Radio Shack SPL meter have to be manually corrected for the bass effect (or a mod made to the electronics), as well. Perhaps the THX design prohibits sending anything but the .1 channel to the sub, so maybe that's why if you have a large speaker all the bass goes there rather than the sub... I don't use any EQs in my system, which is why I haven't compensated for the bass bump in my room. Doug ------------------ My System Quote Link to comment Share on other sites More sharing options...
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