Totally changed response with SVS PB13 Ultra

Badger0-0

Member
One of the members asked me to go and have a mess about with his sub, so I agreed to go yesterday :smashin:
Well you know how it is with REW, when you don't use it very frequently, it's very easy to forget stuff.
So I thought I'd give myself a bit of a refresher with the Ultra :smashin:

Well, I hooked it all up and was shocked :eek:
Now, I'd been saying to the missus for a while that something wasn't quite right with the bass, but couldn't put my finger on it. It had lost it's musicality and I was struggling to hear different tones.

Suffice to say, it was massively different, 10 db differences in places, from when I had last set it up.
Nothing had changed, so I can only assume it's down to run-in.

Has anyone else seen this?

For info, I think I first set it up when it was about a week old and it's now around 3-4 months old.

Having tweaked it a bit last night, it's back to it's usual :thumbsup:, although it still needs a bit more work.
 

gregmcquaid

Novice Member
I saw this as well with my new 20-39 pc-plus. After only a couple of days i used rew to get a really nice flat in room response and i was very happy with the results.

After about 3-4 months i found the bass had changed dramtically for the worse and i re-ran rew and found that there was now a massive dip between 30-40 hz.
I just eq'd it flat again and it hasn't chnaged in ages so i can only assume that it was another piece of equipment causing this is more than likely the subwoofer driver breaking in.
 

IronGiant

Moderator
Has anyone else seen this?
I can imagine REW calibrations being fired up all over the country :) You may have just stuck a stick in an ant hill Badger :thumbsup:

Dave
 

Badger0-0

Member
Cheers for that :smashin:

Well, seeing as my crossover is non-adjustable (flaming THX :thumbsdow) and I haven't altered anything, I'm still tempted to go with my running in theory.

I'll no doubt have another look at in a few months anyway :)
 

chrisgeary

Member
Try moving the SPL meter just a few inches, you may find the response changes dramatically.

I always take my REW readings as a guide. I let my ears make the final decision. Many times I've graphed a 'perfect' response and found it too bass light, too bass heavy, too lumpy. The SPL meter picks up a single point representation. My ears pick up two and moving just a few inches left or right changes quite a lot.

Maybe that accounts for some of the difference as well?
 

Badger0-0

Member
Ah, yes good point, that could account for it, I suppose.
I did try to keep the meter where it was, as best as I could.

I'm the same as you, in that I always use my lugs to confirm what I'm seeing.
I invariably tweak the sub gain a bit.

Mind you, after my quick tweak, the difference is like black and white and I haven't had to touch anything on the sub itself..
I'm a happy bunny again and it just goes to show how good the results are if you make the effort :smashin:
 
R

recruit

Guest
The response on mine changed and I put that down to the run in period, but also re-calibrated my system recently and I noticed a lot more oomph in the Lower Hz <20hz :eek: which I had to tame slightly !
 

Member 96948

Distinguished Member
I have a wooden floor, so I've pencil marked the chairs position and am careful to position the microphone at exactly the same height (97cm) from the floor and distance from the chair.

Inspite of the care taken, every time I run the SMS-1, sometimes just out of boredom, the resulting plot seems to bear little relation to the one I swear I last saw on the screen.

The Monolith is long since run in so the bottom end never changes, but I seem to get extremely variable results throughout the crossover region, to the point where I've had the phase set at anything from 90deg to 135deg.

I have absolutely no idea why.:confused:

Russell
 

Protoplasm

Novice Member
I have absolutely no idea why.:confused:
Does barometric pressure have an effect? I know little about anything here, so I kinda expect to be laughed at. I just wondered since people talk about "feeling" the low frequencies and... yeah... laugh away.

*crawls back under the rock*
 

Badger0-0

Member
@ Russ

Which makes you wonder "what's the point then?" :confused:

Hmm, I wish you hadn't said that :(

Oh well, just shows it's best to back it up with your lugs and not take things as gospel.

As for nipping round the other members gaff, we had a good tweak and by altering the tune and phase, got a much flatter response :smashin:

He put some music on and we both went "where's the bass gone?". Indeed, I had to feel the driver to make sure the sub was working. It was.......just.
Back to the drawing board with that and we're going to have another go next week, time permitting :smashin:
 

Badger0-0

Member
Does barometric pressure have an effect? I know little about anything here, so I kinda expect to be laughed at. I just wondered since people talk about "feeling" the low frequencies and... yeah... laugh away.

*crawls back under the rock*
On the right tracks, so it's not as daft as you think.

Not so much barometric pressure, but different volumes can affect things through resonance.
Manys the time I've had to turn it down to stop stuff resonating.
Doors are a major problem, even though they're shut.

And anyway there's no such thing as a daft question and there certainly won't be anyone laughing at you :smashin:

Even then, I'm not exactly sure on what principles SPL meters work.
"Sound pressure level" suggests you could be bang on the money, although I wouldn't have thought it would make that much difference, tbh.

No doubt someone will enlighten us both :smashin:
 
R

recruit

Guest
When I used to own the Meridian G68 and frequent The Hitch Hikers many people used to have Night and Day EQ setting's, also curtains closed and curtains open settings too :eek: as there is a variety of variables that can affect the listening area and the sound that you hear.

Anyway this is wondering into other forum area territories ie Room Acoustics but interesting all the same.
 

Badger0-0

Member
Anyway this is wondering into other forum area territories ie Room Acoustics but interesting all the same

Agreed. Feel free to move it, but can I suggest that the usual culprits are more likely to see it here as it is product specific, ATM, IMO.

Can you give it at least a day, so the lads who come on here via work, get a chance to see it, is what I mean?
I feel it is more relevant to the Ultra owners.

As for the curtains comment, that's interesting.

When I first took a reading, I realised that the door was wide open.
The sub is on the side wall and the door is at the end of the wall, so when wide open, the door itself is directly in front of the driver, about 8ft away.
I thought it would make a big difference when I closed it, but no, it was fractions of a db here and there, which again surprised me.
 
R

recruit

Guest
I will leave it here for the time being, Neil Davidson regularly frequents the Room Acoustics forum and is a wealth of knowledge when it comes to calibrating/EQ, hopefully he will see this and maybe comment on this subject.

Just another note, I do always prefer movie viewing in the evenings as I feel my system has more impact when compared to watching in the daytime.
 

cribeiro

Novice Member
I can imagine that temperature, air humidity and barometric pressure will influence the SPL readings. I never liked thermodynamics at the university, but I must admit it always comes down to it.

PS: subscribed :thumbsup: Feel free to move it :D
 

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