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25-31PC+ @20Hz -vs- 20-39PC+ @20hz output charts


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#1 of 48 Chris Grillo

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Posted November 20 2003 - 10:08 AM

I am trying to see if I understand the spec sheets on the SVS web site please tell me if I am reading them correctly!!

@ 20Hz the 25-31PC+(tuned to 20Hz)will have 2to3db less output then the 20-39PC+(tuned at the default 20Hz.)Is this correct?

@ 25Hz the 25-31PC+(tuned to 20Hz)will have about the same output as the 20-39PC+(tuned at the default 20Hz) ??

@ 25Hz the 25-31PC+(tuned at default 25Hz) will have 3db more output then the 20-39PC+(tuned to the default 20Hz)?

So if I buy a 25-31PC+ and decide later that I want to tune it to 20Hz. I will only be out about 2to3 db's at 20Hz???
please let me know if this is right!!!
Thanks for your help!!

#2 of 48 WayneO

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Posted November 20 2003 - 10:35 AM

Righto!
If the best advice is "listen for yourself", then why offer your opinion?

#3 of 48 steve nn

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Posted November 20 2003 - 01:31 PM

That is one of the reasons why I like my 25-31CS+'s so much. They sound great playing in both options. If you go dual or better you will have all the headroom needed to really push the envelope SPL wise in either tune.

#4 of 48 Chris Grillo

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Posted November 20 2003 - 02:18 PM

I have been saving up money for the 25-31PC+ and now that I know I will only miss out on 2-3db if i tune it to 20Hz I am sure about my choice!! Thanks for your help guys !!I can't wait to order it !! $300.00 more to save then it's mine!!!!

Ps! Anyone here know what my Boston VR500 may be worth?

#5 of 48 Sebastian

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Posted November 20 2003 - 04:21 PM

3dB is actually a lot. That's twice as loud.

#6 of 48 Yee-Ming

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Posted November 20 2003 - 08:01 PM

Quote:
3dB is actually a lot. That's twice as loud.

I thought 10dB was twice as loud, 3dB is an SPL level where the difference is discernable to the naked ear, and requires twice as much power to achieve (or is that 6dB)?

#7 of 48 WayneO

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Posted November 20 2003 - 08:23 PM

Yee is right, and it's 3db.
If the best advice is "listen for yourself", then why offer your opinion?

#8 of 48 Edward J M

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Posted November 20 2003 - 10:42 PM

The dB scale is log10. A 3 dB increase in sound pressure level is a doubling of the acoustic output. A 10 dB increase is generally perceived by humans as being "twice as loud", but this is somewhat frequency dependent (those Fletcher Munson guys).

I think a better way to look at the 25-31 vs. the 20-39 is what kind of extension you will see in-room with typical room gain factored in.

In a moderate size room (say 2000-2500 ft3) the 25-31 will exhibit strong extension to around 22 Hz in the native tune with all ports open. The 20-39 will troll to about 17 Hz.

Due to its lower tune point, the 20-39 cannot play quite as loud in the >25 Hz region as the 25-31. The difference is probably around 1.5-2 dB.

If you have a large room to fill and are primarily into HT, the 25-31 makes the most sense. If max SPL is not first on your list and you are occasionally into organ music (16-17 Hz), the 20-39 is perhaps the better choice.

While each sub is flexible and can be tuned lower, they are ostensibly designed to perform their best with all ports open in the native tune.

My advice has always been carefully consider your needs and buy the sub that best fits them and plan on running it in the native tune most of the time, with the knowledge you can occasionally tune lower for the odd CD or DVD that requires it.

Regards,

Ed
Ed Mullen
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#9 of 48 Chris Grillo

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Posted November 21 2003 - 01:08 AM

So I guess I have to ask this! Is 2-3db a big difference or not? Now i'm confused. help!! If I had both units and ran one then the other, all things being equal(tuned the same and in the same spot ect.)would I notice a big difference?Posted Image

#10 of 48 Edward J M

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Posted November 21 2003 - 02:05 AM

No, you would not notice a "big" difference in output, but it will be noticeable at the extreme limits of the subs. When the 20-39 reaches its limits, the 25-31 will still have a little bit more gas in the tank in the typical frequency region for hot DVD bass passages (22-35 Hz), and can make the stretch for another 1-2 dB of clean output.

Just keep in mind the limit of both subs is quite high in a moderate size room. I owned a 20-39PC+ for over a year and I pushed it to 112-114 dB (116-118 corrected) at 10 feet from the sub in a 2000 ft3 room and never bottomed it.

Because you are getting the Plus, you might have enough headroom anyway to go with the 20-39 (which coincidentally is SVS' most popular cylinder size).

How big is your room, how many openings are there to other rooms, where will the sub be located with respect to the key listening positions, how loud will you be playing HT, and what are your listening tastes for music? All these questions will help dictate the best sub for you.

Regards,

Ed
Ed Mullen
Director - Technology and Customer Relations

SVS

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"What we do in life, echoes in eternity."


#11 of 48 Chris Grillo

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Posted November 21 2003 - 03:35 AM

Edward J M. Thanks for the reply!
I talked to the guys at SVS and they recomended the p2b-isd
but the size was too big for my room and money was.The closes thing in output is the 25-31PC+ so that is why I am looking at that one:-}. the 25-31PC+ should kick the crap out of my Boston VR500 I hope:-}

#12 of 48 TanT

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Posted November 21 2003 - 03:56 AM

The 25-31PC+ will kick the crap out of your VR500 without any doubt.

FIY: You should be able to get more than this for your VR500

http://cgi.ebay.com/....gory=3275&rd=1

Good luck.

#13 of 48 Chris Grillo

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Posted November 21 2003 - 05:42 AM

TanT,
Holy cow that guy got himself a steel!!!
I would set mine on fire before I sold it for that much!!!!!

Do you own a SVS sub? If so what one? and what did you have before that?

#14 of 48 TanT

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Posted November 21 2003 - 06:20 AM

Yeah, I was going to buy that one too but he wouldn't ship so I didn't bid Posted Image

I had the M&K MX100 (200watts version) for several years in my home theater. I then added a used Velodyne VX810 in my living room for low volume music listening.

I just got my hand on a used SVS CS-Ultra and the Samson 1000 amp.

At first I thought I was going to replace my MX100 with the Ultra but found that while the Ultra has a lot of deep bass it's not as punchy as the MX100 in the upper bass region.

I think I am going to keep them both in my home theater room Posted Image

PS: I've seen and listened to many other subs from my friends and local dealers also Posted Image

#15 of 48 Rich Stone

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Posted November 21 2003 - 06:33 AM

Just fyi, I replaced a Boston SW-10 (an older but very good performing 10" sub) with one of the original 25-31's with the improved driver. Yes the SVS has more extension and output and it does move a lot more air - much more visceral impact.

However, I just can't seem to part with my old Boston SW-10. It has such a nice tight tunefull bass that I just like. I'm considering trying to use both the SVS and the Boston if I can get them to cohabitate together.

Good Luck.

Rich

#16 of 48 Chris Grillo

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Posted November 21 2003 - 07:10 AM

I guess I just want to make sure that if I spend 800+ dollars that I won't be disapointed with the 25-31PC+. I do love my VR500 but I know there is better out thier!

The thing is I may have to sell the VR500 To get the rest of the money for the 25-31PC+ so you can see my delema!!!

#17 of 48 TanT

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Posted November 21 2003 - 07:43 AM

I could see your delema clearly Chris Posted Image

What I've found from my experience is that for low volume music listening I prefer the smaller sub. For home theater and loud volume music I prefer the bigger sub/subs Posted Image

This is why I have 2 systems in my home Posted Image

#18 of 48 Chris Grillo

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Posted November 21 2003 - 08:35 AM

Well I guess I will just have to sell a computer or two to get the money so I don't have to part with the VR500Posted Image

#19 of 48 Chris Xolotl

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Posted November 21 2003 - 01:17 PM

I am three days into my 25-31PC+. My room is odd. 18 foot ceilings (the upper half opens up to another floor). Three Sides closed with one side open to a kitchen. It's a bright room and the two of the SVS guys recommended this or the that PB2.

I've run it with all open ports, 1 plugged and 2 plugged and running AVIA and some DVDs to see if there really is discernible difference. i.e. Should I tune to 20Hz or leave it open at 25Hz.

Mind you, I spend hours a day (for the past 3 days) futzing with it.

Now, after all that testing, I decided that leaving it stock sounded best!!

#20 of 48 Chris Xolotl

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Posted November 21 2003 - 01:25 PM

Also, it provides PLENTY of power. With the sub amp at 40% it gives me about 100db with the other channels at 85db.

I also was using a Rane EQ with it and decided the stock tune is perfect.