Axiom Home Page Forums General Discussion Technical Questions Separates and a sub

I currently have the MT80's VP150 and 4 QS8s' running on a Denon 3803.
110 watts per channel into 8ohm I think it is rated 160 into 4ohm.
Now I have no sub currently although and HSU VF3MKII is landing in my room end of June. ( on layaway now ).
Here is the situation ... then denon volumn goes from -70 db to +15 db. I have to turn it to about -20db when watching a movie ( -15 to -10 db if I am alone watching a movie ) this is my comfort zone, but the girlfriend complains of the loudness.

No way I understand this is my denon is pumping out wattage to produce the bottom end that the MT80's are drawing to produce the low end. I guess this is why I have to turn it up in order to get louder, problem is I have no head room left, if it is needed as the 80's are going to draw current from the amp.

when the HSU arrives will this all change .... since I now have a sub , cutoff will be 80hz setup in the amp as LFE + Mains most likely .. .so know my amp will not be using any current for the bottom end as the sub will be producing the lows and has it's own amp. So, really this should free up a major amount of wattage in my amp ... right ?
I should only have to crank it up to -30db and have 50% headroom left no right.

I am going seperates soon and want the Emotiva or Outlaws mono blocks but, being only sold in US makes it hard on the pocket book, unless the dollar rises higher, which I am hereing very close to even within the year.
No with these if I run 7 channel each speaker has it's own 340 watts module to drain if needed...it's own transformer capacitors etc, and the sub has it's own so it should go defeaning loud right.

I had to read your post a couple times to understand the question -- sometimes the fingers work faster than the brain when you're anxious -- but I think I have the gist of it.

When you get your sub and tell your Denon to cross over at 80 Hz and setting your mains as small, it is true that your receiver won't have to work quite as hard to drive the M80s since it will be relieved of the power-hungry sub 80-Hz duty. This shouldn't have too large an effect on what volume level you have to set your Denon to in order to achieve your desired listening level, however.

Your understanding of power and resulting decibel level is flawed. Keep in mind this rule of thumb: every 3dB increase in sound level requires 2x as much power. So, assuming the dB levels of your volume control are accurate (e.g. every 1dB increment on the display corresponds to a 1dB increment in your room -- and this is hardly ever the case), every 3 clicks of the knob will double the power used. Essentially, this means, in theory, that you still have 50% headroom left at 3 clicks below max.

oh, see I thought if I was up to turn the dial to about 75% it would be bad.

I have no clue what the dB settings on my Denon mean. If anyone has a good explanation, I'd love to hear it.

To get to Troy's issue, at sub-woofer frequencies (30Hz and below), the M80 requires about 1W to produce 66dB at 3 feet (at least in my room it does). So for the pair, you can get 69dB at 3 feet per watt. If you're sitting 8 feet away, you may still be getting around 69dB if your room is quite live. 69dB isn't very entertaining so you probably have it turned up to say 84dB so now you are consuming 32W for those lows. Once you add a sub, your amp will be relieved of these 32W.

More importantly, you have the main volume turned up so high in order to hear the lows that you are torturing you and your loved ones with the mids and highs. Since the 80s are more efficient with mids and highs, you are probably pushing more than 105dBs in those ranges and I am sure you are taxing your amp during dynamic passages.

So when you add the sub, you will have more sane listening levels and it may even sound cleaner too.

The sub will free up a LOT of amp capacity at higher levels, but i doubt it will become a louder system if calibrated right. If anything it might sound less loud as the newfound headroom will eliminate some clipping at high levels. It will sound better at the higher spls though.

Good description Murph.

I want to add that the 85 dB THX reference is for average sounds. Peaks are considerably higher. At this calibrated volume, the peak for each channel is 20 dB higher, or 105 dbfs. The LFE channel can peak to 115 dB.

At reference volume (-0 dB on your calibrated receiver), there is potential of hearing these channel peaks combine to over 118 dB. Listening at -10 below reference for example cuts these numbers by 10 dB.

I just wanted to clarify this, as some may think the reference of 85 dB doesn't sound that high since many like music at 90 dB and above.

As for 75 vs. 85, common calibration tones are offset 10 dB to be easier on our ears and equipment. This is why usually we are asked to set everything to 75dB. But this should result in an 85dB average THX volume when in use.

Yes, this is what I meant.

I have calibrated my system to 75dB using the Denon test tones and my SPL meter. If I turn the volume control to 0dB, I easily hit average levels in excess of 105dB.

I'd like to hear more opinions on what the volume control calibrations mean. I'm starting to think that maybe it's referenced to the voltage across an 8Ohm load with a known frequency.

I am curious what SPL levels you are witnessing when you turn your volume control to 0dB.

Geezzzz
you all gonna be deaf
I am -10 to -20db I would say -15bd is pretty good for me for movies. hell I go louder and the other half is freaking.
Darn 0db gotta be louder than 85db I have a Denon 3803 and at 0db they can hear me across the street