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Author Topic: HPF setting  (Read 4436 times)

Derek Konop

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HPF setting
« on: November 14, 2011, 11:32:26 am »

Hey guys, just wondering if you've got info on how much of a subs x-max is wasted by subsonic frequencies if a hpf is set too low. And I know that it doesn't even need to be necessarily subsonic but anything below a boxes tuning is going to be relatively unusuable due to the amount of power needed to reproduce anything below that tuning point right?

I am using lowriders in home brew shelf ported reflex boxes. I've never measured them so I can't tell you what the tuning of the boxes ended up at. I'm assuming there isn't a way to properly set my hpf accurately without getting measurements on the boxes first?

Thanks,
Derek
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Jeremy McNichol

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Re: HPF setting
« Reply #1 on: November 14, 2011, 12:25:23 pm »

If you have access to a tone generator then you can hook it up to your amp and run a moderatly low signal thru. Sweep down wards from 100hz till you see the cone motion get to a minimum,(it helps if you paint a small white dot on the cone) that frequency will be fB( frequency of the box) then set your high pass from there. Woofers tend to "unload" below fB in ported boxes so excursion and distortion increase quickly. If you don't have a tone generator the you can download free versions off the net and run it thru your computer:)
« Last Edit: November 14, 2011, 07:38:04 pm by Jeremy McNichol »
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Derek Konop

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Re: HPF setting
« Reply #2 on: November 14, 2011, 11:14:12 pm »

If you have access to a tone generator then you can hook it up to your amp and run a moderatly low signal thru. Sweep down wards from 100hz till you see the cone motion get to a minimum,(it helps if you paint a small white dot on the cone) that frequency will be fB( frequency of the box) then set your high pass from there. Woofers tend to "unload" below fB in ported boxes so excursion and distortion increase quickly. If you don't have a tone generator the you can download free versions off the net and run it thru your computer:)

Fantastic! I knew I had read about this process somewhere on the boards before but was unsure. Thanks for the info, I will report back and let you know if I notice a difference in output before audible distortion or over-excursion occurs.

Thanks,
Derek
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Derek Konop

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Re: HPF setting
« Reply #3 on: November 21, 2011, 02:11:43 pm »

Well I did a signal sweep and the tuning point of the box is 31~32 hz. It was pretty shocking how the cone movement dropped right to almost nothing at this point, even with a moderate signal! More importantly, I was able to test the results of the changes I made. I had the PA out with my band both Friday and Saturday night this weekend.

I had a subsonic filter engaged on my x-over that was set 25 hz, and I swept it up to 32~33-ish. The results were.... absolutely shocking! It freed up a ton of head room, These little homebrew jalopies have turned into monsters. I built them to get by on a budget till we could afford better, but I'm actually very proud and happy with the results now.

Thanks for the help,
Derek
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DBA

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Re: HPF setting
« Reply #4 on: November 27, 2011, 09:42:43 pm »

Well I did a signal sweep and the tuning point of the box is 31~32 hz. It was pretty shocking how the cone movement dropped right to almost nothing at this point, even with a moderate signal! More importantly, I was able to test the results of the changes I made. I had the PA out with my band both Friday and Saturday night this weekend.

I had a subsonic filter engaged on my x-over that was set 25 hz, and I swept it up to 32~33-ish. The results were.... absolutely shocking! It freed up a ton of head room, These little homebrew jalopies have turned into monsters. I built them to get by on a budget till we could afford better, but I'm actually very proud and happy with the results now.

Thanks for the help,
Derek

Nothing wrong with LowRider drivers in a homebrew boxes as long as you have the back and help to move them.  Typically they have to be pretty big boxes to make them thump properly.    Glad they worked out for you.   
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Derek Konop

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Re: HPF setting
« Reply #5 on: December 17, 2011, 06:31:01 pm »

Nothing wrong with LowRider drivers in a homebrew boxes as long as you have the back and help to move them.  Typically they have to be pretty big boxes to make them thump properly.    Glad they worked out for you.   

Whit, they are in approximately 9 cubic foot boxes. My plans are around here somewhere, I don't remember the exact numbers. Now that they are high AND low passed correctly I am very happy with them. Being in a small city, green bay WI,  the used market is not all that happenin' for quality gear.

With minimal carpentry skills anybody can build these boxes and put the lowriders and hardware in. If I had simply painted them instead of truckbed liner, the total invest would be $200 per driver and around $125 per box for the materials. A pair of really solid subs for $650. I think at this price point they are a much better option than a lot of the MI level subs available. Nothing amazing but pretty darn good performance/$$$$$ ratio.

Derek

« Last Edit: December 17, 2011, 06:33:09 pm by Derek Konop »
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Jim McKeveny

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Re: HPF setting
« Reply #6 on: December 19, 2011, 10:58:12 am »

It may seem counter-intuitive, but keep your HPF as high as you can w/o impacting performance. It'll clean up a bunch of stuff nobody hears and make life easier for amps & components.
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DBA

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Re: HPF setting
« Reply #7 on: December 21, 2011, 04:34:13 pm »

Whit, they are in approximately 9 cubic foot boxes. My plans are around here somewhere, I don't remember the exact numbers. Now that they are high AND low passed correctly I am very happy with them. Being in a small city, green bay WI,  the used market is not all that happenin' for quality gear.

With minimal carpentry skills anybody can build these boxes and put the lowriders and hardware in. If I had simply painted them instead of truckbed liner, the total invest would be $200 per driver and around $125 per box for the materials. A pair of really solid subs for $650. I think at this price point they are a much better option than a lot of the MI level subs available. Nothing amazing but pretty darn good performance/$$$$$ ratio.

Derek

So they are single 18" design?    What amp are you powering them with?    I recall a nightclub owner needing some bass and the only place to put a sub was a very narrow spot next to the dancefloor.

They build a MDF box for a pair or Black Widow 18"s and it was HUGE.  Narrow depth but it was about 5'x6' widextall or so.   Powered with a simple CS 800 bridged on them, and the damn thing got pretty rowdy and played deep dance music bass pretty impressive for something that they built in an afternoon and had "cheap" drivers and low power. 

Size matters if you need bass from ported boxes and you can't afford these newer very high powerd subs and the proper amps to push them.    I think people have forgotten about "low powered"/high sensitivity drivers in todays horsepower race with speakers. 
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Re: HPF setting
« Reply #7 on: December 21, 2011, 04:34:13 pm »


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