# dual sub calibration standard... i get it... but I beg to disagree! !!!



## Mechsmoto (Aug 5, 2013)

Hi guys,

I know I'm new to the forums... but I'm definitely not shy. While I don't have the vast technical knowledge of many here in home theater and hi fi, nor first hand experience with the elite or high end brands. I do happen to LOVE music and home theater.... i mean something is playing every second I'm awake, and sometime the ones I'm asleep too!!!!

I've stated in the forums several times already I've had first hand experience with pretty much all the big box brands of speakers in both home audio and car audio... and gotten into some higher end car audio stuff.. as well as spent some time doing installs professionally as a younger man.. alpine, kicker, mephis, JLaudio, bla bla.... Part of that being the reason I went into separates. In car audio, you MUST use separate amplifiers for mid high frequency/low sub frequency.... no head unit/reciever is going to push any kind of quality speakers... they are simply for processing. So, once I had the higher powered polk monitor 70's I couldn't help but want to give them a decent amp to pull off- hence the xpa5. (I'm getting to my point ... hang in there) 

Once I'd added the xpa5 (I had the onkyo 818 at that time)... i still felt like something was missing from my normal sound. This was my first time with audessey xt32. Prior to xt32 I'd never used the auto correction as I felt it was inferior to my own ears(strictly opinion). I'd always set everything up at 0.0 on all channels.... no bass/treble... flat. I'd then turn on one channel of the receiver in stereo mode so i could really hear how clear the speaker was.....and found where the speaker started to sound harsh, back it down a bit.. usually around 1/2 volume on the older recievers. This would become my max volume or (my reference/preference..whatever you'd like to call it is fine!!!). I would then tune my sub using this volume and a heavy bass cd... until I heard the sub sound stressed back it down a lil bit usually around 12-1pm on the subs gain. If I had two subs I would set both subs the same way.....which leads to the whooooooole point of this post.

Audessey XT 32 suggests when using dual subs, that you set them up to 75dbs combined.... The "standard" is to set each sub to 70db's which gives them a combined total of 75db's... which I will admit does give you roughly 5 db's of headroom.... and the normal 75 db for audessey XT32 to be happy.

NOW, the reason I challenge this needs to be explained a little bit to actually "click" and make sense..... 

Ok so let's use me as an example. I already had two psw505's that I was happy with prior to having xt32(using my own tuning procedure). The onkyo 605 I'd had prior to the 818 sounded great to me with the same two subs?!?!? I searched the net to see what the consensus was... and ended up with the old "xt32 is cleaner sound through more filters, giving a flatter response.... you'll get used to it". Wellllllll, what if I don't want to get used to it!?!?!? I want my bass!!!!!! Sooo, I spent the money on dual psa xv15's. .. DUAL subs NOT ONE sub. 
I got them, hooked them up dialed them in just as audessey suggested... and played them. I wasn't at all impressed ... i actually was disappointed as it sounded the same as the polks more or less, and I felt like I'd wasted my money. I knew that the xv15's were waaaay better than the polks... so, this led to a million emails (not really but lot of them to Tom V at PSA. He was super patient and helped me like he was my friend ... Post sale now... for months... trying to figure it out. I want to get to the point and make a novel into a short story... so let's just say.. like most of you. I ended up settling for the lower level of bass.... I'm not a kid anymore anyway.

Well let's just say, I never really let it go... and when I started reading on the forums about the diy build I thought "18's vs 15's, giant enclosures, several kilowatt amps. .. it's gotta be insane"... then I started checking into the numbers and doing my OCD research. I see 120db's in room 130db... even with these giant enclosures. I know for a fact I have emails from Tom V stating the xv15's could hit mid 120's- 130db in my room (10' x 12' x 8'...I can dig it up if anyone doubts me). Well needless to say, I tested this theory the other day using Pacific rim bluray. I intentionally set the subs up at 78db each which gave me 83dbs combined. 8db over reference. We all agree that reference is 115db and with bass management the subs can be asked for a peaks of 121-123db. Add 8dbs to this and you're asking for 129-131 db's. I don't have an spl meter to verify it. But If any movie tests this... it's Pacific Rim!!! I played the entire movie 0 db on the 929. I watched the subs with my face all pressed up against them literally. Even in the nastiest scenes the subs would work split seconds and return to barely moving! !!! The control of the driver is extremely impressive to watch especially for such a big surface area!!!!! There was not a single second of the movie that the subs didn't have more left in them!!!!! I was completely amazed!!! I was certain that I would here something I didn't like, or see drivers going bananas when the kaiju's were stomping around... not even @ 1:54-1:55 in the movie where the Reverse explosion pulls back through the water did they have an issue... and I promise you they Stiiiiiiiillll had more!!! I forgot to mention the xv15's gain was only at 12:30- 1pm to achieve 78db each at my listening position. The reciever sub gain was at 0.0. 

This led me to my conclusion, and the whole point of this thread. Let's use me for an example again... i bought 2 xv15's. I didn't buy one and I sure didn't buy two to make them sound like one!!! I don't have $800 to through out there for 5 db's of "headroom". What I bought the second sub for .... was to have the feeling of two xv15's!!!! (I did get two xv15's for the headroom of an extra powersupply/250 watts rms/and the ability to even the response in room at the cost of 150 vs a single xv30... just being completely honest here). So if i bought them to sound like two, why in the world was I buying into this "calibrate them like their only one sub" controversy that's been driving us all bananas. 

Simply put the second sub can give you 5 db's headroom OR 5 db's (hot- without actually being hot) THIS is why I spent double the money! !!!! More spl!!!!!!!!!!! Correct me if I'm wrong .....pleeeeeaase.... but seeing them each at 75db's gives you the sound of two subs. Not decreasing the spl of each to equal the spl of one!!!!!!
Neither sub works any harder than they would individually, yet you get 5-6 db's of extra power!!!!! This makes my xv15's produce the spl of an xv30... NOT the same sound of one xv15!!!! Immediately after my test. I setup the system with each sub at 75 db. Ran xt32 and then went in and raised my subs back up the 5 db's xt32 takes away. Giving me the extra 5 db of spl and still allowing each sub to work normally....without being made to run hot. 
Since making this change I've had the sound that I have always had all over again..... just much cleaner and tighter... bla bla... The way I would expect xt32 to make my system sound. In my case it was $800. How much are you dual sub owners paying at the moment to hear what one of your subs sounds like??!?!? I encourage you all to try it .... if you already have.??!!!.. maybe I'm the only caveman left In the world that didn't know! !!!!!!! ??????


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## Sonnie (Apr 11, 2006)

I have eight 18's in my room... but it is not necessarily for SPL... it is for better balance and smoother response. Nonetheless... when I setup my Audyssey, my subs are already level and delay matched with using the amps and my DEQ2496, therefore I only use one sub preout on my preamp/processor. I don't pay any attention to the sub level setting that Audyssey recommends. The SPL is typically 85dB or so and it tells me to lower it before moving on. I ignore it... let Audyssey do its thing and then I set my sub level to my liking. I don't let Audyssey dictate my sub levels.


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## morca (Aug 26, 2011)

I also don't let Audyssey dictate my sub levels,often you have to lift 10 db after running ADSY.


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## Sonnie (Apr 11, 2006)

Another thing to keep in mind is that Audyssey does not do well with the larger peaks in the room and will cause your sub level to be lower than usual if you do not tame those peaks prior to running Audyssey, which is why I use the DEQ2496 prior to Audyssey. Actually Audyssey does not have to do too terribly much in my sub region.


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## morca (Aug 26, 2011)

Indeed,i helped someone on a local forum,he had the same problem.
I think the roommode between 40-50 hz make,s ADSY make a mistake.

I advised him to put the level on his SVS from 50 to 70 %,and make a new ADSY run.
Afther the sub sounded better,but even then the 10 db was missing,he adjust + 10 db and it sound great.


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## lcaillo (May 2, 2006)

Whether you want more bass or not, two subs will not only give you headroom but lower distortion at high levels, in most cases.


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## Mechsmoto (Aug 5, 2013)

Hey guys!!!! Thanks so much for input!!!! Definitely makes me feel better to see others agree. 

I have had many email conversations with Tom V. I'm pretty sure we can all agree that he KNOWS subwoofers.!!! When I explained to him I needed to raise the level, all his explanations described running the bass "hot". I interpreted that as a negative. As he would go on to say most people didn't run the bass "hot" AND use full reference volume. That this would quickly become "fatiguing" to listen to for any period of time. 

I think this scared me away from it in the beginning.... besides that, I'd had one of the bases of an xv15 that was vibrating off a high spot in my tile floor... so the first few times I tried this, I'd here the vibration off the enclosure and floor and worry I'd hurt something. When I finally realized what was going on I wrote Tom and nd neither if us could believe, we hadn't figured it out much sooner.!!! Ha ha!!!


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## Mechsmoto (Aug 5, 2013)

Sonnie, 
8- 18's !?!?!? Woooow!!!!!! Is your theater room the size of a gymnasium or what?!?!? That's awesome!!!! 
I'm thinking if you wanted to be ridiculous with those subs you might be able to make hair stand up in that room of yours!!!!!....


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## Mechsmoto (Aug 5, 2013)

So basically we are using XT 32 to set our satellites distances, levels, and to set the eq for all channels. My question is..... Post calibration, after xt32 sets the sub level at -10 or -5 for example, and we set it to back to 0. In effect, all we are changing is the level of the sub NOT xt32's eq?!?!?!?

I'm asking because i feel if xt32 is hearing the subs channel "hot" it could possibly be over correcting. If this Is the case, why not run the calibration at 70db's each.... to get xt32's truest calibration(as close to 0.0db as possible)... then go back and set the subs gain to whatever we would normally use. This way audessey doesnt make any unecessary corrections!?!?!?

What are your opinions on this! ?!?! Maybe you've already checked into this using rew?!?!?!? I'd be VERY interested to know what's the difference between running the calibration the two different ways.!?!?!?!??!


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