New to subwoofers.. Help a newbie out?

ToMMyGuN

Limp Gawd
Joined
Jul 9, 2008
Messages
327
Hello all of you audiophiles (read: soundsnobs ;) )

I am new to the world of subwoofers. I recently purchased a receiver (Kenwood Vr615) that has a sub amp built in. I connected it to a big passive DLK Subwoofer (bought at a garage sale for pennies :) ) and am obviously getting much more bass / bass response than my previous Klipsch Promedia 2.1 set. I am using an X-fi Xtreme gamer (5.1) out to the Kenwood (direct 6 ch. in) to the speakers. I am using some ancient DLK 1 1/2's for front and KLH bookshelves for rears.

My question has to do with getting a new sub. I was watching parts of The Dark Night, and my sub seemed to be bottoming out. I don't know the low range freq cap on the sub, but it must not be near today's standard (the DLK speakers were made in the late 70's and are quite a bit older than i am ;) ). What is an acceptable lower frequency roll off? I am looking at getting a used Boston Acoustics PV700, which has a freq cap of 29hz. Would this be a good buy for me (a college student trying to be as cheap as possible?) Any opinions of the sub in general?

Another question i have: could i run the sub directly from the sound card (bypassing the receiver)? the reason i ask is that the receiver doesn't have a line level (pre) out for the sub..

One last thing - Any general advice on subs? i am a bassaholic and need that boom, and was wondering if there is general knowledge you all can bestow on me :)


Thanks In advance!!
 

Sysjack

Limp Gawd
Joined
Oct 6, 2003
Messages
339
You said it was a passive sub, but then you talk about pre-outs for it, so I'm not sure which you mean (passive or active). A passive speaker has no amplifier and is driven by the source, in this case your receiver. A computer sound card definitely does not have the power to drive any passive speaker larger than headphones, certainly not a power-hungry subwoofer.

Personally, I look for a low end around 20Hz or better for a sub, but I like deep deep bass.

Edit: Sorry, looks like I didn't read as thoroughly as I thought, missed where you said the receiver has a sub amp built in. That would have cleared up my confusion. I would like to know what you mean by "bottoming out" though.
 
Last edited:

Digital Viper-X-

[H]F Junkie
Joined
Dec 9, 2000
Messages
13,904
You said it was a passive sub, but then you talk about pre-outs for it, so I'm not sure which you mean (passive or active). A passive speaker has no amplifier and is driven by the source, in this case your receiver. A computer sound card definitely does not have the power to drive any passive speaker larger than headphones, certainly not a power-hungry subwoofer.

maybe I missed it, but he said this receiver doesn't have a pre-out meaning the sub is being powered by the receiver itself, he is asking about the new sub woofer being run directly from the sound card, which by the way is possible, you will need a mini jack splitter to separate the front / sub channels and find out which is which by some trial and error
 

Sysjack

Limp Gawd
Joined
Oct 6, 2003
Messages
339
I think you are right that he wants to run the new sub from the sound card, I didn't make that connection.

Certainly possible to pass signal from sound card to a powered sub. The problem with doing that though is that if you using digital out to the receiver you will have to control the speakers and sub separately. If analog signal is going to the receiver you can control both simultaneously only if you find a balanced setting you like on the hardware volume knobs and adjust volume through windows, which kind of sucks. Another alternative may be to find or make an attenuator to bring the receiver output down to a pre-out level, which would allow you to keep it connected to the receiver.
 

ToMMyGuN

Limp Gawd
Joined
Jul 9, 2008
Messages
327
My current sub is passive (being run by the sub amp on the receiver).

The sub i was looking at getting (Boston Acoustics PV700) is an active sub. I was wondering what the best option would be for getting signal to it. If i pass is the signal from the receiver, it would be an amplified signal; i could feed that into the powered speaker jacks (red and black) on the back of the sub, and just not feed my front speakers from the sub. If i bypass the receiver and go direct from the soundcard, i would have to (like you said) control them separetly (or with windows :-( ). What is the best way to get the sound to the sub? would hooking the amplified signal up to the sub's "speaker in" jacks hurt the sub at all? I am using the Analog connection as the xtremegamer doesn't support 5.1 digitally

Is the 9hz difference between your recommendation and the PV700 (29hz) worth looking elsewhere? would i be able to get a 20hz sub for cheap (100 bucks used)?

Random sub question:
What are the benefits of a 12" sub over a 10" or 8"? is the main benefit simply that the 12 physically moves more air?
 

Syndicated_Death

[H]ard|Gawd
Joined
Feb 8, 2005
Messages
1,604
you sure that receiver is putting out an amplified signal. almost all sub outs are preamp to a powered sub. is this a RCA jack were are talking about or speaker connection?
 

Sysjack

Limp Gawd
Joined
Oct 6, 2003
Messages
339
Found the manual here http://inform3.kenwoodusa.com/manuals/vr605.pdf so it looks like there is indeed no pre-out for the sub on his model, but most of the other similar ones have it.

For $100 I guess you can't be too picky about it, the PV700 should do fine. After you get out of school and work for a living you can upgrade. I did notice that some places advertise it has having one useful feature in particular, that being "Line and speaker level inputs". You should look into that.

The 29Hz is almost certainly the 3dB point, so don't think of it as a hard cap. You will get some, but reduced, bass extension below that.
 

ToMMyGuN

Limp Gawd
Joined
Jul 9, 2008
Messages
327
The 29Hz is almost certainly the 3dB point, so don't think of it as a hard cap. You will get some, but reduced, bass extension below that.
Could you expand on what you mean here? I think i know what you are getting at, but i am not sure.. :) Just trying to learn a little :)


Anyone have any experience with the PV700?
 

Tangent inc.

Limp Gawd
Joined
Oct 5, 2006
Messages
398
You use the "High Level/Speaker Level" inputs from your receiver's sub output. the sub you mentioned does have this option and attenuates the the signal voltage accordingly. The only issue may be noise but is not a requisite.

This option is intended for use with sources such as a two channel receiver and would need proper attention payed to crossover and gain. In your instance the receiver should be passing the appropriate signal regardless.


oops... sorry sysjack. i didn't refresh before i replied and you said it all.

The 29hz is where the extension starts to roll off. if you are watching a movie and you are getting 100db at 29hz the loudness will begin to drop fast the lower the frequency gets, usually by dbs per octave. The + or - 3db states that in ideal conditions you the system will not deviate more or less then 3 decibels from top to bottom - say 150hz to 29hz or what ever the case may be. The in room response may be lower because you are playing in a confined area.
 
Last edited:

Alai

2[H]4U
Joined
Jul 19, 2008
Messages
2,701
If you're talking about some of the soundtrack of The Dark Knight, don't worry about it too much. It's the soundtrack itself that has a smeared bass sound, not the subwoofer itself.

I've tried the soundtrack on various audio systems and they all have smeared bass.
 
Top