Reaching the limits of my PB-10 ISD? (1 Viewer)

[Vaughan Odendaal]

I haven't been here in a while, and I see that no one had answered my questions. So I'll just ask again and hopefully someone will respond;

Rob, can you please tell me how loud your PB-10 goes in your room when you play the LOTR ring drop scene? Thanks. And to everyone, if I got myself a BFD, and, for example, I managed to tame a few big peaks in my subwoofer's response (or my room's response), does that mean that I can play my subwoofer louder before the onset of compression?

Thanks. I played Master and Commander today, and I was impressed, but there is one thing that disappointed me (as with LOTR). There is no fixed level that I can use that will preserve maximum dynamic output and extension unless I lower the volume too much, and then it's a lost cause.

For instance, in Chapter 4, when the cannons go off, it sounded awesome. I could feel some of the bass. Excellent. But later on in the Chapter, there are much louder and lower cannon blasts, and it lasts for a few seconds. You see, with the master volume at -15, I'm getting deep, clean bass, and it's loud. But there are certain demanding scenes later on in the Chapter that compress heavily.

If I lower the volume to -20 from reference, then I am getting 100% compression free output, because the last few cannon shots go deeper, slightly louder, and the room sort of pressurizes more (I don't know if it's resonance or decay or something).

So it's a little frustrating that I can't put the master volume at a certain level and just leave it alone because certain bass heavy scenes get compressed. The only way that I know that it's compressed is if I put the volume at -10, and slowly increase the volume noticing any differences in bass impact.

Ed, you were right, to get reference level in my room, I'm probably going to need around 4 Pb-10's. But something tells me that if I need to keep the volume at -20 to preserve bass impact on the most demanding bass passage, then I'm probably going to need about 6 SVS PB-10's to reach it. Unless I'm completely wrong.

I will be purchasing another PB-10 next month though.

--Sincerely,

 

[rob-h]

Sorry about that! I forgot to test and I have my theater room a mess to put in my new speakers, reciver and platform. I will answer this for you asap. Probably early next week.

 

[rob-h]

Also, decrease your recievers subs level so that you dont have to turn down the master volume so much. You can get a second pb-10 and put it closer to your seating position. That will dramatically improve SPL. I tried that but it was actually too much.

 

[Vaughan Odendaal]

Are you suggesting that I lower the subwoofer level so that it's less than 75dB's (compared to all my speakers), because the last time I calibrated, I had the subwoofer set to 72dB's.

However, I think that I'm going to recalibrate tonight. I'll borrow the work's SPL meter. I don't know if it's as good as the Radio Shack one, but it's the only one I've got.

Now I don't know if what I'm doing is correct, but this is how I calibrate with the meter: in the seating position, with the SPL meter pointed towards the ceiling. C weighting, slow. 70dB position, and once it's hit the +2 reading, it's accurate to 75dB (given the inaccuracy of the meter at low frequencies)?

Is that more or less correct? I haven't tried putting the subwoofer directly behind the couch, but that would be a bit impractical (I'm still living with my parents).

--Sincerly,

 

[Vaughan Odendaal]

I tried something. I watched Master and Commander Chapter 4 on our reference setup (M&K powered speakers with a single 5000 Ultra subwoofer at the moment) and I noticed that at -18, there was some compression. It sounded great still at -8, but there was a lot of compression.

People wouldn't normally think it's compression if they didn't decrease the volume from -8 to -18 from reference, but there you go. However, I'm feeling all sorts of things with this subwoofer. Then again, the room size is about 2200 cubic feet, the subwoofer is positioned directly behind the couch, and it's 1 meter away from me.

Not even an M&K MX-5000 THX Ultra 2 subwoofer can reach uncompressed bass output at -15 with that particular cannon blast in Chapter 4. Oh well, I'm starting to feel a bit better now. . . And this thing retails for R34000! I paid R5900 for my SVS.

Extension wise, I couldn't tell much of a difference between the two. But I think it will be quite a bit more powerful since it's enclosure is bigger and it's using two 12" drivers.

--Sincerely,

 

[Edward J M]

It's nice to see you are developing some field impressions and some practical experience about maximum output and compression vs. strictly distortion limited output. It's also nice to see you have noticed the M&K is not immume to compression either.

While people initially tend to fixate on the clean output numbers (and they are very important), output compression is probably one of the most offensive types of signal distortion. Once you notice compression, you listen for its effects on nearly every heavy bass passage.

If -20RL is the maximum uncompressed limit on M&C in your room and specific set-up and with the sub properly calibrated, then you can either live with that or start adding subwoofers.

Reducing the sub calibration level a few dB in order to up the MV a few dB makes sense to a certain point. You are basically running the sub "cool" to afford a higher overall playback level. There is a limit to this practice, because eventually the level of bass output will be disproportionately low with respect to the speaker channels. You might be able to run the sub 5 dB cool and push the MV up to -15RL, but that's about the coolest I'd run the subwoofer.

Again, it's all about matching your playback preferences with the capabilities of the subwoofer. I think you'll find that four colocated PB10-ISD will generally cover just about any reasonable playback level in that room, but if you are really interested in RL playback, then you might indeed need six of them. Of course six of them gets a little silly, which is why SVS offers larger dual and quad 12" woofer models.

I run dual PB12-Ultra/2 in a 1800 ft3 room. I need a reference standard by which to judge all other review subwoofers, and this set-up provides it. In my fairly small evaluation room, at any playback level, this set-up is completely free of audible artifacts, distortion, or compression. Your system should always have some clean headroom left in the tank at your highest preferred playback levels - at that point your level of subwoofage is "sufficient".

 

[Vaughan Odendaal]

Excellent points as usual Edward, thank you. For starters I'll just buy another one. I don't really need to listen at reference, but -10 from reference for me, at least, would be ideal.

Just a few things: the way in which I calibrate my system, is that the correct way to do it (in the above responses)? Edward, you know I am learning, and it's great, because I'm becoming more able to discern the difference between compressed and uncompressed output.

You have helped a lot in that regard, so I thank you for that. But yeah, duel pb12-ultra/2 must be nice! You definitely have more than enough headroom in that size room. But when more and more material comes along that provides bass extension that reaches down to the single digit's (there are few), it's a requirement, I think.

I mean, with those bass flicks that have energy down to below 10hz, duel pb12-ultra/2's don't seem like overkill anymore.

Cheers.

--Sincerely,

 

[Edward J M]

I usually point the SPL meter upward at a 45 degree angle. If you are using the AVR test tones - with the MV set at 0.0, adjust each speaker channel to 75 dB, and adjust the subwoofer to 72-73 dB (c-weighted slow). The sub level will bounce around a bit - maybe a low of 71 and a high of 74 will get you a 73 dB average.

Again, you could drop the sub level a few more dB to buy yourself some extra MV increase for a louder playback level in the speaker channels. But I wouldn't go more than about 5 dB "cooler" on the subwoofer channel, though. The bass will sound thin, but you'll still have enough to hear/feel.

 

[Jack Gilvey]

So, I think we can conclude that a cheapest-in-the-line PB10 will compress at a certain level on the most demanding bass scenes we can find. More money can get more performance. If you really want to feel the sub-20Hz stuff, a Buttkicker is much cheaper and easier than trying to vibrate all that air.


In case you missed it above, mastering levels, and individual scenes, are all over the map.

 

[Vaughan Odendaal]

Thanks Edward. I really appreciate you taking the time to help me out.

--Sincerely,

 

[Vaughan Odendaal]

Jack, yes, I now know the limits of my subwoofer. I didn't think I would have reached them so quickly and so easily, though. I assumed that the PB-10 would have been more than enough. That was my mistake.

All I can say is that this deep bass stuff is getting really addictive now. I just want more and more now.

--Sincerely,

 

[Jack Gilvey]

Yup...you can't go backwards.

 

[Edward J M]

Uh oh - we've created another Frank Manrique.

Welcome to upgrade-itis.


And the jump to dual Ultra's just as noticeable, I imagine.

 

[Jack Gilvey]

As will the jump to four. No, wait...I can't...

 

[Edward J M]

You will be assimilated.

 

[Vaughan Odendaal]

Sorry, I had a question on the other page that I think went unnoticed. If I buy myself a BFD, and, for instance, I managed to bring down several large peaks in my subwoofers response, would that give me additional headroom?

Would it be worthwhile to invest in one? Perhaps someone could elaborate on that. I'm 22, quite young, and, well, I'm moving out within the next six to seven months, so I won't be able to play things too loud. I think I will want to get a bass shaker. My quesion to you is, which bass shaker would be advisable to go for?

I know that you get different brands and different types, but for my application (not excessive vibrations, just a good butt shake to compliment my PB-10), that wouldn't be too expensive? On another note, do you, Ed, personally have a butt shaker (or similar device), and if not, why not?

Thanks for the help.

--Sincerely,

 

[Vaughan Odendaal]

Uh oh - we've created another Frank Manrique.

Heh. That guy is simply insane. But I think I'm on the right track though. . .

Cheers.

--Sincerely,

 

[Wayne A. Pflughaupt]

Generally, no. The reason is that you’ve calibrate the sub’s level based on the peaks. Cut them down and your sub level will be too low. Of course, then you have to raise the gain, so you end up right back where you started.

Regards,
Wayne A. Pflughaupt

 

[rob-h]

After starting a remodel on my theater, the front wall seems like a great place for 4 pb10's. I now have 2 for them supporting my axion 150 center. 2 more should fit there nicely. Its good to have a dedicated theater....

 

[Vaughan Odendaal]

That's cool, rob. I'll be getting another pb10 next month. Gee, I haven't even written a review yet. Darn. I got my new digital camera today, so I'll be able to take some high resolution shots of it.

I'll write an in depth review of the subwoofer next week. It's the longest overdue review ever.

BTW, this is completely off-topic now, but are you knowledgable on video editing software by any chance?

--Sincerely,