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Discussion Starter · #1 ·
Wow, this software REALLY shows ya what's going on, I can't believe the difference in FR I am seeing moving my sub around!!
I knew there would be some, but the shift's I am seeing are mind boggling.
Great Job!!

Donation is on it's way.

I just built a 2cu Rythmic Direct Servo 12 last weekend(right now- just the raw cabinet- with the amp and driver- finish TBD), and I noticed some notes seemed ALOT stronger than others, so I ventured over here to see what was up with the REW/BFD...

No BFD yet unfortunately.....

After moving it around the room some, I came up with this(I have a few options, depending..)- SPL was Cal to 81.4db, 80hz XO on PP(120hz on sub XO),24db slope, using the Rat Shack correction file for the model I use.... I hope I do this right.... I'm trying guys, I've been reading....

This seems like a decent starting point to me, what ya guys think?
Thanks,

m

Text Line Purple Pink Plot
 

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Re: 1stday using REW

what ya guys think?
There is an elite group of sub owners who don't need to equalize because their natural room response is so good.

You happen to be in that group. :praying:

And look at your bottom end extension. Beautiful.

You even have a house curve without trying.....

Yeah, you could make the plot perfectly smooth with an eq, but you wouldn't likely notice any difference.....

Nice sub.

brucek
 

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Re: 1stday using REW

Yep, I agree with brucek.

You can apply BFD if you want, but that's an excellent curve right there.

Good job!
 

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Discussion Starter · #4 ·
Re: 1stday using REW

Thanks guys.

I thought it looked good, it sounded very good yesterday, but I am listening to it in it's "BETTER" position(graph wise/XO as well), and it sounds even better.
I didn't get a chance to actually listen to it after running those sweeps/moving it around, because it was much too late(glad those sweeps are short duration!! bahahaha)..

This thing went from VG sounding yesterday- to a REALLY good sounding sub overnight!!...
I need to leave the door open for the Audio Fairies more often..... and to think, I only put an Oatmeal cookie under my pillow!

Thanks again....... I think I'll enjoy it for awhile(and to think, I was out looking for Music/Guitar shops today while driving for work- for an 1124P), before I decide what to do... :bigsmile:

m
 

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“This seems like a decent starting point to me?” “What ya guys think?” Please. I think you’re just rubbing our faces in it! :laugh:

Seriously, that is amazing response, especially the extension! Personally I think that some smoothing between 20-70 Hz would be beneficial. Based on my own experience, when I had a slight bump in the 50 Hz range - I could hear it. But that’s with music. If this is a HT-only application, I’d say you’re done!

Regards,
Wayne
 

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Discussion Starter · #6 ·
Thanks Wayne,

I listen to alot of music on my Ascend Sierras, hence the reason for building this particular sub (I agonized over LLT/Ported,Sealed), I even picked the 12" instead of the 15 because of music(not that a 15 can't do music)...

It seems to do HT just fine(I'm CERTAIN there are others that DESTROY it), but music was my #1 priority, HT 2nd.

I HAVE heard a few notes on songs, that seemed a bit weird(NOT on songs I own- digital audio from cable- for background listening), not sure what it was...

I haven't recalibrated levels since last night, so I'm wondering if maybe it's a bit out of phase(adjustable-pot, 0-180), or if it is those humps....
Unfortunately, tonight is not a night to listen loud here, so I guess I won't be able to run Avia or DVE to find out....

I actually wasn't sure how good it looked(like I said, it looked like a good starting point to me), until I looked around till after 3am this morning, looked at a buttload(thats what happens when you see your own graphs- I'm sure ya'll have been there!!), and realized that it was pretty good as is.

I still think I'm gonna get a BFD, but at least I know I don't have to hurry to at least enjoy my sub!

BTW, I had the sub in 14hz/low damping mode for that graph.

Thanks Again,

m
 

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Discussion Starter · #8 ·
Ok, I ran it, and recalibrated with the mains running, I moved the speakers everywhere, but there is a nasty dip centered around 111hz, it MUST be the room, I will have to treat the room to get rid of it.
I adjusted the phase, and it WAS around 125deg, and it's sitting at about 45 now.

It's hard to judge exactly WHERE the XO is on the sub, because most pot's I've seen(and used) aren't linear- Audio pots are supposed to be better though... I tried what looks(on the dial) to be 100, 110,120, and full blown 160.

The farther I move the XO, the peaks(low end) get higher, and pinches the dip narrower- but to no avail........
I am trying to determine between 110 and 120, 110 has a couple SMALL dips below 80.5(target), 120 is high enough over, that I could EQ it DOWN flat.

I am attaching the jpegs for you guys to look over(TOP is 110hz,bottom is 120hz), any advice is appreciated, but I'm thinking the 120 and get rid of peaks, I'll have a bit more headroom for the smoothing... at least thats my theory!! LOL (plus the dip is narrower a bit, and doesn't extend down as far)...
It's obvious that the room needs work...

EDIT: if the horizontal scale should be set different, let me know I can extend the upper end instead.

Thanks Again,

Gary
 

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It's hard to judge exactly WHERE the XO is on the sub
I'm confused Gary. Why are you using the crossover on your sub itself and not the crossover (bass management system) in your receiver/preamp? Normally you would dial the subs own low pass filter (XO) as high as it will go, so it won't interfere with the receivers bass management. Some subs have a bypass switch and some you need to dial the pot fully clockwise to get the low pass up to ~160Hz or higher. Then the reciever handles the 80Hz crossing of the mains and sub...

brucek
 

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Discussion Starter · #10 ·
I'm not so certain I trust the BM on my BA AVP7 pre/pro(Sherwood Newcastle P965 clone)...., and AFAIK the rythmic doesn't have a bypass.

He even states to adjust for correct response in his Amplifier Manual section(pdf), so thats what I did(would have anyways without a bypass).

Is he wrong?

It's funny, he mentions 12 oclock, 9 oclock etc...(as XO/Phase settings...),thats how i lable them here!! bahahaha
 

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Discussion Starter · #12 ·
BTW, I calibrated my mains, and the sub B4 starting tonight, and I had the PA on TONIGHT(for the mains-just shut it off when testing the sub B4)... I found the reading to be 6 db or so higher, so I calibrated using the SUB tone with Sub AND Mains(to 80.5 db) on at the same time.
This was correct to do right? Otherwise they were additive, and the SPLS were alot higher.

I was like, ummmmm sub test, full range test... ummm sub test!!!
 

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Hi muzz,

I'm not so certain I trust the BM on my BA AVP7 pre/pro(Sherwood Newcastle P965 clone)
.

Why wouldn't you trust the bass management of your preamp?

He even states to adjust for correct response in his Amplifier Manual section(pdf), so thats what I did(would have anyways without a bypass).

Is he wrong?
Well, I'm not sure who "he" is, but I think I'd set any sub-internal crossovers as high as possible and then use my preamp to set the crossover points. Give it a try, and I think you might enjoy the results. I'm thinking that the BM of the preamp and the crossover of the sub amp are interacting in a fashion that creating that dip, especially since we don't know what frequency the sub amp is affecting.
 

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Is he wrong?
Yep, if you use the bass managment of the receiver (which you should). What's not to trust? If you don't use the receivers bass mangement you won't be able to set the crossover frequency of your mains. Hopefully you're not runnig them full range, because the resulting interaction with the sub offers poor results.

This was correct to do right? Otherwise they were additive
Yep, that's correct. When you add the mains, the levels setup needs to be revisited, but you still use the sub pink noise etc., as if the mains weren't there. Don't use full range setup when you add the mains - just reset the levels and test. :)

If you don't trust the receiver simply use REW to do a loop response test to check it out. We can help you with that if required.

brucek
 

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Discussion Starter · #15 ·
The "HE" I referred to is Bring Ding, the Owner of Rythmik Audio, and the inventor of the Rythmik Direct servo system.
Sorry about that- he talks about it in his amplifier Manual.

I do have my mains set to Small, and the XO is set to 80hz(on my PP).
As you can see in the 3 sweeps posted above, the XO on the sub makes a difference, but it's not a MASSIVE difference ONCE I set it past the XO from the PP, once I get AROUND 100hz(on the SUB XO- like I said what is it ACTUALLY), I start to see lower values/less output, which shows me that it's either around, or below the PP XO set point.

Thanks Guys,

m
 

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I do have my mains set to Small, and the XO is set to 80hz(on my PP).
It is simply a bad idea to combine low pass filters this way. If you are using the bass management in the receiver, then dial the subs own crossover to maximum and don't use it.

If you have problems around the crossover, then they are ameliorated by adjusting the subs phase, receiver sub distance control trim, positioning and equalization. You never combine low pass filters that way.... :no:

brucek
 
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Just to borrow this thread a bit because I am interested in this first graph. I notice in the first post it says the SPL was calibrated to 81.4 but then the graph is up in the 92 range and everyone talks about how great a curve it is. I thought the point was to get it close to the SPL target. I think may have been trying to optomize something I don't need to. Do you just plot a curve and try to be as close to that curve in terms of drop-off as possible. Then when you get rid of all the peaks, you recalibrate the system (mains, center, sub, rear) to 75db across teh board with the EQ on using the pink noise from the receiver. The trick being you use the level on the sub to turn it up and down versus the adjustment on the receiver.

I ask this because with the EQ off I get exactly 75db response from each and every channel at my listening position. Obviously to get the sub to 75 I have to adjust the level on the sub. While I'm testing and EQing, the level continue to decrease and I have to keep adjusting the level on the sub up or the volume on the receiver up to get it back to 75db. However, my curve is always up around 78 or 79 and I've been trying to bring it back down to 75 with equalization.

I may be doing more equalization than necessary.
 

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I thought the point was to get it close to the SPL target.
Most users like the sound of a small house curve. If muzz had added a house curve it would have tracked quite close to it. He got it without even trying.... If he didn't want a house curve and he indeed wanted the target he shows, then he would need to bring his response down to meet the target.

Do you just plot a curve and try to be as close to that curve in terms of drop-off as possible. Then when you get rid of all the peaks, you recalibrate the system (mains, center, sub, rear) to 75db across the board with the EQ on using the pink noise from the receiver. The trick being you use the level on the sub to turn it up and down versus the adjustment on the receiver.
You're placing too much emphasis on the exact 75dB number. It isn't really important. The idea behind all this is to equalize the peaks out of the sub. That's it.

It's convenient with REW to use 75dB as a center point. The object is to get rid of the subwoofer response peaks. Once that's done - set the level of it and any speaker to whatever you like.

Generally (once you've eq'd the sub), then the level you set the trims and subwoofer to is controlled by the receiver test tones. You try and match them. Doesn't matter what the actual SPL level is. Could be 81.66dBSPL - as long as they're matched. Some people like the sub a bit hot, so turn up the sub amp a bit.

brucek
 

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I thought the point was to get it close to the SPL target.
I may be doing more equalization than necessary.
If you’re equalizing across-the-board response down (or up) to the target curve, then yes, you’re doing too much equalizing! If you get a plot like muzz's top one, you can turn the sub down and run REW again, to get in range of the target curve before equalizing. That's mainly to make it easier to track the curve, however; if you can smoothly EQ above or below the curve, then go right ahead!

Regards,
Wayne
 

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Discussion Starter · #20 · (Edited)
It's getting a lil better, I put a throw over the Leather sofa to dull some reflections, and it seems to be helping that dip a bit, 84 db target:

Edit- Set XO on sub to full, like the last blue pic above.
 

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