Do I Really Need a Sub?

[Nuri58]

He was right. I had placed them in the center of the wall by measurement and with that wall being 7" longer it was 3 1/2" further away. We moved it 3 1/2" down the wall and the bump was gone. I can only guess that the subs on the front and back wall are so much different in distance to the speakers it is not an issue.

Front and back even worse. You get the sound from the rear somewhat sooner than from the fronts and if you cannot set the distance to the subs individually and as such the room correction if your room is not perfect.

 

[Brad225]

Front and back have never been a problem. It is interesting that if a piece of music is bass shy, I can turn up the volume on the rear wall sub that is behind me. The bass line increases in the sound stage exactly where you would want it to be.

Should you turn any sub up way to much you would know its location. Other than that you never know the location of any of my subs.

 

[Chops]

My supplier could not get it calibrated correctly due to the time factor so I dumped my old sub altogether

Not to sound rude, and please don't take it the wrong way, but maybe your supplier's capabilities are in question... IF the sub(s) in question had variable phase and there was a reasonable distance from the subs and listening position, there should be no reason why he couldn't have dialed in the timing on that other sub.

I've set up and calibrated subs many times in friends/clients systems in the past with one or two subs up near the front and one somewhere in the rear of the room with great success.

And as Brad mentioned in his post about his subs, you could not tell where the bass was coming from. Even with the rear sub in one system dialed in a little hot for a more tactile effect, all the bass sounded as if it was coming from the main speakers.

I don't know if I need it or not, but I'm actually contemplating the idea of getting another JL e110 to put in the rear of my room. It's a small room and I'm getting excellent results as is right now where I currently have the subs located, so who knows if I'll actually ever do it. I never have yet with any of my past systems, but it was more of a lack of funds, room and a constant changing system.

 

[Chops]

Charles, I don't think of myself as old either but, there are activities as you describe that are a challenge on many days.

My thought process. I'm sore to day, I guess I should just relax and listen to some music.

Any time you would like to come this way my door is always open.

I watched them rounding up the Swans this morning on the local news for the yearly checkup. That won't mean much to most people.

Most days I wake up feeling fine, others, not so much, but I go to work anyway. Then again, it helps that with this new job (been there a year now), the people I work with and for are great, and I'm not longer in retail with varying hours and days, so I don't mind it at all.

I swear, one of these days, I'm going to take you up on that offer. Nice thing is, I'm always off on weekends now, so much easier to make plans like that.

The vet that we take our cats to, she is the main one that does the checkup on those huge birdies all the time. She actually cares for the animals' well being.

 

[BDH55]

This is an awesome forum! Thx so much for all the great feedback. Based on everything I've read here, my current plan is...

First, recruit my neighbor to help me position my existing Descent i and do the sub crawl...

Second, place my Descent i at the appropriate location, and run high level connections to it off my mono blocks (I'm currently only running the LFE channel off my AVP)...

Third, I'm going to run this for awhile just to get used to things since I've never had a sub on my LR channels before...

Finally, if I like what I am hearing, I'll go ahead with what was my planned upgrade to a BF 212... and 'possibly' to a pair of BF 212's...

Frankly, I'm probably trying to do too much at once but I am trying to plan out my steps to avoid as many mistakes as possible. I am still dealing with final positioning of my ESL 15A's... and since I have a significant birthday upcoming, I have an Illusion C34A on the way (happy birthday to ME!). Once I get those two dialed in, I think that is really the time to get serious about my 'sub project'...

Sound like a plan?

 

[Nuri58]

Not to sound rude, and please don't take it the wrong way, but maybe your supplier's capabilities are in question... IF the sub(s) in question had variable phase and there was a reasonable distance from the subs and listening position, there should be no reason why he couldn't have dialed in the timing on that other sub.

I've set up and calibrated subs many times in friends/clients systems in the past with one or two subs up near the front and one somewhere in the rear of the room with great success.

How do you avoid the time factor? The bass from the rear hits you like 10 mS before the same bass hits you from the front? At least this was my issue.

 

[Chops]

How do you avoid the time factor? The bass from the rear hits you like 10 mS before the same bass hits you from the front? At least this was my issue.

Again, that's what the variable phase control is for (also known as phase timing). On my JL's, its range is between 0 - 280 degrees (I think I said 270 earlier, but that's not important). Depending on where that rear sub is located and its distance to you compared to the front sub(s), you may have to use the 0 - 180 phase switch in conjunction with the variable phase control to get proper alignment. And keep in mind, even slight position adjustments of the subwoofer itself will aid in tweaking the timing as well. Sometimes just a few inches is enough.

And gain!... Don't forget proper adjustment of the gain. When it's all said and done, you shouldn't even notice that there's a pounding sub sitting behind you.

 

[Nuri58]

Ok, that might make sense to me. Bu in that case the bass management in Dirac is not indispensable, but it'll require some time to get it right.

 

[Chops]

Ok, that might make sense to me. Bu in that case the bass management in Dirac is not indispensable, but it'll require some time to get it right.

Yes, it'll take a little time to get right, but you should be able to manage. Just work with one subwoofer active at a time. When you have each one dialed in, all you have to do then is get all of their gains set properly to your mains and you should be good to go.

I don't like using digital room correction. Just something about it never sounds right, and it's just more garbage in the signal chain. My version of room correction is the act of physically moving things around to make it all work. I get the best results that way.

If you try getting that 3rd sub working, let us know the outcome!

 

[amey01]

And keep in mind, even slight position adjustments of the subwoofer itself will aid in tweaking the timing as well. Sometimes just a few inches is enough.

How does that work when we're talking about wavelengths of around 17 metres? That is longer than any listening room on this group!

That said - I don't know if my sub is perfectly dialied in - but I am certainly happy with the results. I positioned it by putting it in the listening position with final tweaking through a DEQ2496.

 

[Chops]

How does that work when we're talking about wavelengths of around 17 metres?

We're referring to milliseconds of timing, not propagation of frequencies. A major difference.

 

[ttocs]

How does that work when we're talking about wavelengths of around 17 metres? That is longer than any listening room on this group!

I spent a few days last week rearranging 3 subwoofers in the room. This was a performance-first operation striving to find where "each" subwoofer works best - in conjunction with - where "all" the subwoofers work best together. The attached plots show a before and after from moving one subwoofer 14". All 3 subwoofers were active in both plots. The purple is the before moving the small sub into its current position.

So yes, when talking about the longest wavelengths it took a lot more movement to get a happy response. This is what I worked at the most in the beginning with the two larger subwoofers (twins) to get the low frequencies their best. But the final move which, which was not big at all, didn't only change things around that 100Hz area, but also changed the lowest frequencies. The only tools I used were delay and gain. No PEQ, crossover, or corrections are being used to produce these plots.

 

[amey01]

We're referring to milliseconds of timing, not propagation of frequencies. A major difference.

But milliseconds on a 17m wave ain't gonna change anything?
Or is it?
How?

As I understand, subwoofer placement is more about room modes and interaction.

 

[Chops]

I feel like I'm repeating myself at this point.

 

[amey01]

I feel like I'm repeating myself at this point.

You don't have to be impolite - but not quite - you don't understand the question.

Let me give you a hint - you'd have to move the subwoofer 8.5 metres to achieve a 180-degree phase shift in the primary. Unless of course, you're talking about room modes which.......now I feel like I'm repeating myself.

 

[Chops]

I'm not being impolite, I do understand the question, and I've made several posts about the situation.

Let me give you a tip... You don't have to move the subwoofer a single inch to achieve 180 degree phase shift. Pretty much every powered subwoofer on the planet has a 0 - 180 degree phase switch built in. However, not all subwoofers have a variable phase (timing) control. For the ones that don't, you would have to employ a stand alone active crossover or DSP. But I'm not going to go into anymore detail here about it.

I have done this sort of setup many times over many of years in many systems with great success, as well as many others that have done the same on their own with their own systems.

Good thing this discussion isn't about subwoofer swarms.

 

[amey01]

I'm not being impolite, I do understand the question, and I've made several posts about the situation.

I really think we're talking at cross-purposes.

I'm pretty sure we both know how to integrate subs reasonably well - even if there are some who would call me a "cheater" because I used a DEQ2496!

I'll leave my further knowledge acquisition to another source

 

[Chops]

I'll leave my further knowledge acquisition to another source

LOL! Okay...

 

[Chops]

Soundoctor - all about subs

 

[BDH55]

I've been running high level connections to my Descent i for a few weeks now and loving the results (and to be honest, I haven't actually done much other than making the connections, so I can only imagine how much better it would sound once I invest the time). While I am liking what I'm hearing, one thing I'm not crazy about is the heat being generated by my Para JC-1's. You can absolutely feel the temperature change when walking in and out of the room, and it is not a small room. I only noticed this after I added my sub to my main amps. Any thoughts about whether I should worry about this configuration?