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Chief2001

Audioholic Intern
Hi All,

I have had my HSU VTF-2MK5 subwoofer for about a month and a half now. It's my first sub and it is paired with a music only system. My room is 13x13.5x8, but there is a 6x8 opening that opens up to the rest of the house. I have a 45 watt push/pull tube amp driving Duntech PCL25 speakers (which are rated at -3db at 55hz). The sub is connected via a Bryston preamp outputs, so no ability to limit the output to the main speakers.

After a month of mucking around with placement and various configurations of adjustments I'm getting close to really dialling it in (which all goes out the window when my son wants to listen to rap with me :)).

The one thing I am wondering about is that when the sub is off, I have much better imaging and sense of presence. Highs and mids tend to be better. When the sub is on, at moderate levels, some of the mids, highs, and imaging is smeared or losses some focus (a bit...I'm pretty picky). At high volume levels, I don't seem to be able to get the same impact and spls with the sub on.

Do you think a high pass filter, like the one sold by HSU, would help with the loss of focus and the compression at higher volumes?

Thanks for your consideration.
 
ski2xblack

ski2xblack

Audioholic Field Marshall
Hmm. I think we need more info to help diagnose your problems.

What occurs to me is that it's possible that when blasting it you're clipping the tube amp, which generally exhibit soft clipping characteristics closer to compression than obvious/gross distortion. It will shatter the illusion if you're clipping the amp.

The Hsu high pass filter you mention is likely to protect the ported sub from excessive cone excursions below tuning frequencies (where the driver un-couples from the port output). From your description of events, that doesn't sound like it would be a solution. It is probably a good idea to protect your subs from teenager spls and hip hop, though.

How high are you running the sub's low pass filter? Perhaps there is too much overlap between your subs and mains. Subs, properly balanced with the mains, should enhance imaging, not detract from it.

Regarding compression, if that's in fact whats going on, you may get better results by implementing bass management, which would provide slightly more dynamic range, key word being "slightly". What are you working with as far as the pre-amp goes? Does it have bass management?
 
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Chief2001

Audioholic Intern
Thanks for your reply.

I'm running the low pass between 60-65 hz.

I cannot use any bass management with my preamp. My understanding, and I may be wrong, is that the high pass filter would act as a form of bass management, allowing my amp to send signal above a certain frequency to the main speakers, like around 60hz.

I hear what you are saying about compression. I know how my system sounds without the sub when compression sets in. With the sub, I'm not sure it is so much a matter of compression as a "muddying" of the sound, due to my mains playing full range. May be both compression and bass cancellation going on...not sure.
 
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Chief2001

Audioholic Intern
Thanks. Do people think it would help with the issues I have mentioned above?
 
lovinthehd

lovinthehd

Audioholic Jedi
Thanks. Do people think it would help with the issues I have mentioned above?
I prefer such for my subs over merely the blending method, but don't have a Hsu HPF box, use various avrs and miniDSP units (and measurement mic/REW). Hard to know over the internet what you're hearing, one way to find out :) I'd think you're duplicating frequencies to an extent the way you have your LPF set.
 
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Chief2001

Audioholic Intern
Do you think raising the LPF to 70 or 80 or lowering it further would be better?
 
lovinthehd

lovinthehd

Audioholic Jedi
Do you think raising the LPF to 70 or 80 or lowering it further would be better?
If you raise it you'd be duplicating more...I'd go lower but experiment, we all have different preferences....
 
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shadyJ

Speaker of the House
Staff member
One possibility is that the bass frequencies from the sub are masking the mids from the speakers. The louder the sound is, the greater the frequency bandwidth that the bass will mask, especially if it is running hot relative to higher frequencies. The solution to that is to turn the subwoofer volume down.

If that is the problem, than the high-pass filter won't help in that regard, but I would still get a high pass filter for other reasons and benefits.
 
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Chief2001

Audioholic Intern
Thanks for all of your advice, everyone! I will try lowering the low pass and sub volume.

What would the other benefits for the high pass filter be Shady J?
 
TLS Guy

TLS Guy

Seriously, I have no life.
Thanks for all of your advice, everyone! I will try lowering the low pass and sub volume.

What would the other benefits for the high pass filter be Shady J?
I think it is a simple matter of your sub being turned up too high.

You should NEVER hear a sub.

What you have is a good way of using a sub. Using good main speakers full range and just supplementing with the sub is one of the best ways to use a sub.

The rule is to set the sub crossover at the F3 of the mains plus 50% for starters.

You then just advance the its volume until it just gently supplements the mains. Even when standing right next to it you should not hear it. When playing program with no content below 40 Hz, which is most, you should not be able to tell whether the sub is on or off. When playing music with content in the last octave, (40 to 20 Hz) your should notice a subtle enhancement of the lower end.

The problem with subs is the mentality that: "I paid a lot of money for this sub, and I jolly well want to hear it!" In reality subs should be seen and not heard.
 
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Chief2001

Audioholic Intern
Very well said, TLS Guy. I think you nailed it. I think I'm trying to get "too much" out of the sub, ie wanting to feel impact or deep bass that just isn't there.
 
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shadyJ

Speaker of the House
Staff member
Thanks for all of your advice, everyone! I will try lowering the low pass and sub volume.

What would the other benefits for the high pass filter be Shady J?
Other benefits would be alleviating the woofers from your main speakers from attempting to play deep bass. The can reduce distortion and mechanical stress on the woofer, since the subwoofer is so much more adept at low-frequency playback than your other speakers. It can also allow your main speakers to play a bit louder than they normally would, because you aren't as likely to overdrive the woofers. Also, it offers better control of the sound since overlapping frequencies of the crossover point between the sub and the main speakers are much better controlled.
 
S

shadyJ

Speaker of the House
Staff member
I think it is a simple matter of your sub being turned up too high.

You should NEVER hear a sub.

What you have is a good way of using a sub. Using good main speakers full range and just supplementing with the sub is one of the best ways to use a sub.

The rule is to set the sub crossover at the F3 of the mains plus 50% for starters.

You then just advance the its volume until it just gently supplements the mains. Even when standing right next to it you should not hear it. When playing program with no content below 40 Hz, which is most, you should not be able to tell whether the sub is on or off. When playing music with content in the last octave, (40 to 20 Hz) your should notice a subtle enhancement of the lower end.

The problem with subs is the mentality that: "I paid a lot of money for this sub, and I jolly well want to hear it!" In reality subs should be seen and not heard.
One rule of thumb that I have been told which seems like good advice for those who don't have the tools to measure and integrate a sub by graphs is to just use any sound mix that has James Earl Jones' voice in it, since he has such a deep baritone voice. When listening to a scene where James Earl Jones' is speaking, adjust the sub volume so that his voice seems natural and isn't coming from the sub. Systems where the sub is running too hot will always make James Earl Jones' voice sound boomy and the sub will be obvious. However, if you get James Earl Jones' to sound natural with the sub in play, that is probably pretty close to the level the sub is supposed to be at since a good chunk of his voice is actually coming from the sub.
 
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