I am going to be building a ported box for my 12" Alpine Type R and I am going to need a SS filter. However, my current amp (JBL 300.1) does not have one. Can you buy inline filters like you can with crossovers, and how much approx. do they cost.
And one other thing where would you go to buy port tubing?
Thanks,
Jay
Replies (17)
uochronos on 08/8/2004 16:02:42
at crutchfield and thezeb they sell harrison labs filters you just get one that matches your port tuneing frequency. they have one that block 50,45,40,30,25 Hz and below i believe and they are aproxamatly 25$.
port tubing can be bought at thezeb.com, crutchfield.com, and partsexpress.com. also most car ausio shops sell these but you have to ask for them as they arre usualy a backroom item. they would rather build you a box then have you just walk in and get all the material for one:)
swez on 08/8/2004 17:43:34
Yep, Harrison Labs has a good solution called F-MODS. These are passive filter networks that connect between you HU and amp (inline RCA's) that will block out lows at a -12dB/octave slope. That's not a bad slope to protect your woofer in ported applications.
If you port at say 40 Hz., a 40 Hz HPF will be 12dB down at 20 Hz., and ~6dB down at 30 Hz. Will that be enough filtering to protect the subs? If bass boost or lots of EQ is used at 40 Hz., we can override that filters function and render it useless.
If we go to a 50 Hz., HPF, we are 12 dB down at 25 Hz. (Not bad) That would make us ~ 6dB less at 37.5 Hz., -3 dB at 44 Hz. We can make that up a bit with EQ or a little bass boost at 40 Hz. If your amp has that feature, (and it does) the 50 Hz., HPF makes more sense.
Finally, if you have multiband EQ or a good parametric sub controller, this will work by "padding" (cut back) all frequencies below PTF. (Port tuned Freq.) The higher the dB of filtering, the better for your sub. Especially if it is a -18 or -24dB slope at PTF.
This may be a very good solution for an active SS filter. It is a programmable 2-way Crossover unit with a selectable SS filter. You can select (modify) both Low & High pass frequencies to amps and modify the SS filter module that is normally preset at the factory @ 33 Hx. It is an -18dB filter.
http://www.audiocontrol.com/PDF/OwnersManuals/MobileAudio/2XS_CS_OM.pdf
Swez
I would love to see a 24dB slope SS filter. But to my knowlwdge, only better bass amps have them... have to buy an active filtering device or make a 4th order passive SS filter and install it into the enclosure. Even some of the high end HU's have SS filters... but at that level of HU, we are talking a very pricey package.
LC1 on 08/9/2004 16:22:00
I called the Alpine Tech center and they gave me dimensions for a tube port and slot ported box. That said it will tune the sub to 35Hz. What passive crossover should I use? Should I block everything below 30hz or what?
Swez with your explaination above with using a 40Hz HPF down to 12db will be 20Hz I don't quite under stand what you are talking about.
Once more thing is a SS filter absolutly necessary? I am wondering because I called a few car audio shop here and only one of them knew what I was talking about. And another said he has a ported box with no SS filter and said that I shouldn't really need one.
Thanks,
Jay
uochronos on 08/9/2004 17:15:57
alot of the shops here say the same thing... i have seen so many friends blow subs and get all mad but its because they didnt have a SS filter.
almost all the power going to your subs below the tune frequency is turned into heat not movement so your sub eventualy just over heats and you burn a voice coil or other part up.
can you drive around wihtout using a SS filter sure well they sound ok probaly. well it cause damage yes. my one friend ran his subs for a year but they eventualy blew the Voice Coil.
and for only 25$ extra to block damaging your speakers why would you not do it. you can either spend 25$ now or 10$+ down the road rerplacing subs as they go out.
alot of times whyen you talk to someone at a shop especialy over the phone its a sales rep not an installer at alot of places they guys only know what they need to know to sell the gear. i had one guy tell me i was going to "blow" the sub i was comparing to another sub because i only had the sub on i didnt have any mids or highs and this can cuase damage to the sub. he freaked out and told me to leave. to say the least i know that i wasnt hurting the sub but he didnt know his stuff. alot of times find a sales manager or a installer and they can help more.
swez on 08/9/2004 21:18:16
SS filters are a good insurance policy when using ported subs. If low frequency (signals below PTF) are present in the audio content, the sub "unloads" (cone becomes unstable) and goes into cardiac arrest mode.
Sorry if I was getting too deep for ya on the crossover stuff. Basically, we want to filter out as much audio signal power below PTF as possible to prevent woofer destruction.
For example:
We talk about SPL in dB or decibles. This is a unit of measure as to how much acoustic output an audio system can reproduce. We know that audio signals are electrical impulses from a source like a HU or amplifier. The amout of voltage it can put out, can be converted to dB's of sound pressure level. Hense SPL. The speaker (transducer) converts this electrical energy into sound waves. How much sound we hear out of that speaker is generally expressed as SPL in dB. (not voltage) Did I lose you yet? Hope not...
Now, with ported sub applications, we know there is a lot of bass energy in todays' music. Some lows we can hear very well. Very low frequencies, (subsonics) are signals present, but we cannot hear them. We may feel them at a theater with movies like Volcano, Jurrasic Park and such... but we really cannot hear them. The subwoofers used in these applications are massive and designed to reproduce bass below human hearing. Best most of us can hear is ~25-30 Hz. Bolow that, it's mostly below our hearing ability... but we can feel it.
OK, back to business on filters. Say you have a sub and amp. The amp is say 300 RMS and the sub is moderately efficient. (89 dB of SPL at 1 watt, 1 meter away) The sub will reproduce bass well in sealed enclosures and net about 125 dB of SPL in bass range of 40-150 Hz. As the sub gets signals below ~ 40 Hz, the dB # will naturally rolloff at a predictable rate. (slope) The term used in audio is -X dB/octave. In the case of a sealed box design, that slope is -0dB at 40 Hz., -6dB loss of SPL at 20 Hz., -12dB at 10 Hz. (these are octaves)
In ported designs, the Port Tuning Frequency (PTF) determines how low the sub will play and still be distortion free. When porting, we get a nice passive peak in bass near the PTF. That peak is about +3dB more than a sealed enclosure will deliver with same sub and same power input. So now, you have +128 dB of output VS the 125 dB we mentioned earlier.
Near the PTF, the cone produces very little audio. The sound comes from the port. The cone does not move very much at PTF as the back pressure in the enclosure is being released into the port. That means the lack of cone movement, reduces cooling of the voice coils. This is where a lot of subs get fried. Not much movement and loads of power being dissapated in the form of heat. That's what fries a sub coil.
Below PTF, the cone motion returns, but there is so little backpressure in the box, it cannot control the cone movements. Basically, this acts like there is no enclosure at all. (a "free air") sub is the result. With no control over the cone movement, the sub goes spastic and will often jump the gap or the coil bottoms out. Again, the result is a damaged sub.
When we use a SS filter, the filter will remove a goodly portion of sound energy that would normally pass to the woofer. The larger the slope of the filter, the better. Less watts of power (SPL) to the sub, below PTF is how we protect expensive woofers. The most efficient way to do this, is prior to amplification. That helps the amp as it does not waste large amounts of power, trying to amplify signals below PTF. In car audio, we don't get much music content below ~35-40 Hz. If PTF is say 40 Hz., we want to filter out as much signal content as possible, as we approach PTF. This is where good filtering is needed.
Let's say a sub is getting 300 watts of signal at 40 Hz. That's pretty loud stuff. Now, insert a 40 Hz SSF, 12dB/octave and the output watts will drop to (~20 watts) flowing to the sub at 20 Hz. That's safe for the sub to dissapate heat in that range. A 40 Hz SSF, 18dB/octave slope will lower the power to sub even more. Here, the sub is getting about 4.5 watts at 20 Hz. The basic line of designing a good filter, is to know that for each 3dB of sound we filter, it drops the watts input to the driver by 50%.
Here's a chart:
dB slope/octave........................................wattage to speaker
0dB reference...(no filtering).....................300 watts @ 40 Hz.
-3dB........................................................150 watts @ 20 Hz
-6dB.........................................................75 watts @ 20 Hz.
-9dB.........................................................37.5 watts @ 20 Hz.
-12dB.......................................................18.75 watts @ 20 Hz
-15dB....................................................... 9.38 watts @ 20 Hz.
-18dB....................................................... 4.7 watts @ 20 Hz.
See how that works? It's logrithmic, not linear.
We see this in sub amps VS mid/highs amps. Sub amps are much larger and produce large amounts of audio output. Mid/high amps are smaller and it takes many less watts to generate a +120dB signal to the mid/high speakers. (~60 watts will do) A sub needs more like 150 watts to get the same +120dB of SPL.
WOW... that's along winded explaination. But I hope it helps you and others that read this post. If you have more questions, will bo my best to answer them.
Swez
PS Most audio sales people and installers are just that.... installers and sellers. This is design and engineering type stuff. Don't expect them to know it, unless they have studied it in depth. I am not an Expert in this area, but I have studied it a while now. Hopefully this presentation of a very complex subject, is simple enough to learn and use. I'm trying my best... but it may still be too deep? Comments?
uochronos on 08/10/2004 02:44:20
wow Swez excelent explanation.... i think we need to put that in the DIY area because hoenstly i didnt even udnerstand it that incredibly well till i read that and now that i saw all the formula and what not it all makes wonderfull sense..
thats definatly a helpfull explanation. i think alot of people are confused about why you need an SS filter and this explanation helps alot.
P0werLifter on 08/10/2004 03:12:26
Bump, I agree that should be posted in the FAQ or DIY sections. In reading your post Swez that helped me understand why we need SS filters etc. GREAT EXPLANATION!!!!!!!!!! Sometimes things get to complicated for someone who is just starting/someone whos been learning to understand in one reading. GREAT Post
Thanks
Jason
swez on 08/10/2004 17:13:44
Thanks guys... I am waiting for LC1 to check in on this one too. If he got a handle on the topic, hit the target.
Will have to edit it down a bit too for FAQ/DIY ... too long.
Swez
LC1 on 08/11/2004 14:40:30
Swez,
Great post as I said before in the chat room. I went to Audiomagic yesterday and they had an older Hi-Fonics active crossover @35Hz -18dB . It was somthing he had from about 4 or 5 years ago he said and he sold it to me for $25CDN. This is a bit off topic but I actually found out that the guy who I was talkign to owns the shop and he lives four houses down from me and is friends with my parents lol. So now I know who to go to for anything else I may need. He even offered me an Alpine amp at cost as well, one they had in the back room and forgot about.
Anyways thanks for the great help swez & uochronos. Going to start building my sub box on the weekend. Just finished up my blueprints on the computer with Autodesk Inventor.
Actually do you guys mind taking a look at my drawings and make sure I have everything cover? (NOTE: There is no top pannel on the drawings.)
The pictures are here: http://www.pbase.com/lc1/vented_enclosure
Thank you very much,
Jason
LC1 on 08/11/2004 14:46:10
Also forgot to mention that the box is supposed to be 1.75 cu/ft with the port and sub displacement factored in. And the overall dimensions are located on the bottom left. The ones on the right are what to cut the pannels at.
http://www.pbase.com/lc1/vented_enclosure
Thanks again,
Jay
uochronos on 08/11/2004 15:25:06
look like a very well planned out box. and from the looks of it a very good design as well. it should net very good results
swez on 08/12/2004 18:38:30
Very well drawn and planned. This is more like a transmission line enclosure. Stronger low end bass and almost perfectly in phase outputs at cone and port. This is much better than average performance we get from most port tuned enclosures.
Just make sure you accounted for all the baffle panels displacement wise.
9.5" x 13.75" x 0.75" = 98.0 x 2.75 vent panels = 270.0 cu in. of port displacement + sub displacement # needs to be included in the gross internal airspace of this box. (or something pretty close to that)
Swez
LC1 on 08/13/2004 00:45:13
Just one more quick question on this topic. I heard that when a sub in a ported application distortion is harder to tell, is that right? So do I just adjust my gain/HU settings the same way and when I heard the sub distort just back off on the gain a bit?
Thanks,
Jay
P.S. After this weekend when I build my new enclosure I will let you know how it sounds.
P0werLifter on 08/13/2004 00:52:10
Very Nice Plans. Where did u find the program? Ive been looking for one like that.
~Jason
LC1 on 08/13/2004 01:14:27
P0werLifter,
I got this program from a co-op job that I was on last year. I am a Mechanical Engineering student and we use that for all kinds of engineering drawings. I don't know if it would be possible to send you a copy of it because it is a pretty big program. But the program is called Autodesk Inventor. My version is 5.3 but their up to 7.0 or 8.0 now. You may be able to find it online somewhere.
Jay
P0werLifter on 08/13/2004 01:42:51
Cool thanks Jay ill be lookin for it. Rebuilding my enclosure for my subs. 3.0 CuFt for each sub Tuned to 30hz
swez on 08/13/2004 07:52:02
Yes, gain setting is the same technique as mentioned before. However, power handling will be a tad less at lower frequencies as the PTF comes into play.
If you have a test tone CD, try it out below PTF and see how well the filter works on that amp.
Swez
And one other thing where would you go to buy port tubing?
Thanks,
Jay
Replies (17)
uochronos on 08/8/2004 16:02:42
at crutchfield and thezeb they sell harrison labs filters you just get one that matches your port tuneing frequency. they have one that block 50,45,40,30,25 Hz and below i believe and they are aproxamatly 25$.
port tubing can be bought at thezeb.com, crutchfield.com, and partsexpress.com. also most car ausio shops sell these but you have to ask for them as they arre usualy a backroom item. they would rather build you a box then have you just walk in and get all the material for one:)
swez on 08/8/2004 17:43:34
Yep, Harrison Labs has a good solution called F-MODS. These are passive filter networks that connect between you HU and amp (inline RCA's) that will block out lows at a -12dB/octave slope. That's not a bad slope to protect your woofer in ported applications.
If you port at say 40 Hz., a 40 Hz HPF will be 12dB down at 20 Hz., and ~6dB down at 30 Hz. Will that be enough filtering to protect the subs? If bass boost or lots of EQ is used at 40 Hz., we can override that filters function and render it useless.
If we go to a 50 Hz., HPF, we are 12 dB down at 25 Hz. (Not bad) That would make us ~ 6dB less at 37.5 Hz., -3 dB at 44 Hz. We can make that up a bit with EQ or a little bass boost at 40 Hz. If your amp has that feature, (and it does) the 50 Hz., HPF makes more sense.
Finally, if you have multiband EQ or a good parametric sub controller, this will work by "padding" (cut back) all frequencies below PTF. (Port tuned Freq.) The higher the dB of filtering, the better for your sub. Especially if it is a -18 or -24dB slope at PTF.
This may be a very good solution for an active SS filter. It is a programmable 2-way Crossover unit with a selectable SS filter. You can select (modify) both Low & High pass frequencies to amps and modify the SS filter module that is normally preset at the factory @ 33 Hx. It is an -18dB filter.
http://www.audiocontrol.com/PDF/OwnersManuals/MobileAudio/2XS_CS_OM.pdf
Swez
I would love to see a 24dB slope SS filter. But to my knowlwdge, only better bass amps have them... have to buy an active filtering device or make a 4th order passive SS filter and install it into the enclosure. Even some of the high end HU's have SS filters... but at that level of HU, we are talking a very pricey package.
LC1 on 08/9/2004 16:22:00
I called the Alpine Tech center and they gave me dimensions for a tube port and slot ported box. That said it will tune the sub to 35Hz. What passive crossover should I use? Should I block everything below 30hz or what?
Swez with your explaination above with using a 40Hz HPF down to 12db will be 20Hz I don't quite under stand what you are talking about.
Once more thing is a SS filter absolutly necessary? I am wondering because I called a few car audio shop here and only one of them knew what I was talking about. And another said he has a ported box with no SS filter and said that I shouldn't really need one.
Thanks,
Jay
uochronos on 08/9/2004 17:15:57
alot of the shops here say the same thing... i have seen so many friends blow subs and get all mad but its because they didnt have a SS filter.
almost all the power going to your subs below the tune frequency is turned into heat not movement so your sub eventualy just over heats and you burn a voice coil or other part up.
can you drive around wihtout using a SS filter sure well they sound ok probaly. well it cause damage yes. my one friend ran his subs for a year but they eventualy blew the Voice Coil.
and for only 25$ extra to block damaging your speakers why would you not do it. you can either spend 25$ now or 10$+ down the road rerplacing subs as they go out.
alot of times whyen you talk to someone at a shop especialy over the phone its a sales rep not an installer at alot of places they guys only know what they need to know to sell the gear. i had one guy tell me i was going to "blow" the sub i was comparing to another sub because i only had the sub on i didnt have any mids or highs and this can cuase damage to the sub. he freaked out and told me to leave. to say the least i know that i wasnt hurting the sub but he didnt know his stuff. alot of times find a sales manager or a installer and they can help more.
swez on 08/9/2004 21:18:16
SS filters are a good insurance policy when using ported subs. If low frequency (signals below PTF) are present in the audio content, the sub "unloads" (cone becomes unstable) and goes into cardiac arrest mode.
Sorry if I was getting too deep for ya on the crossover stuff. Basically, we want to filter out as much audio signal power below PTF as possible to prevent woofer destruction.
For example:
We talk about SPL in dB or decibles. This is a unit of measure as to how much acoustic output an audio system can reproduce. We know that audio signals are electrical impulses from a source like a HU or amplifier. The amout of voltage it can put out, can be converted to dB's of sound pressure level. Hense SPL. The speaker (transducer) converts this electrical energy into sound waves. How much sound we hear out of that speaker is generally expressed as SPL in dB. (not voltage) Did I lose you yet? Hope not...
Now, with ported sub applications, we know there is a lot of bass energy in todays' music. Some lows we can hear very well. Very low frequencies, (subsonics) are signals present, but we cannot hear them. We may feel them at a theater with movies like Volcano, Jurrasic Park and such... but we really cannot hear them. The subwoofers used in these applications are massive and designed to reproduce bass below human hearing. Best most of us can hear is ~25-30 Hz. Bolow that, it's mostly below our hearing ability... but we can feel it.
OK, back to business on filters. Say you have a sub and amp. The amp is say 300 RMS and the sub is moderately efficient. (89 dB of SPL at 1 watt, 1 meter away) The sub will reproduce bass well in sealed enclosures and net about 125 dB of SPL in bass range of 40-150 Hz. As the sub gets signals below ~ 40 Hz, the dB # will naturally rolloff at a predictable rate. (slope) The term used in audio is -X dB/octave. In the case of a sealed box design, that slope is -0dB at 40 Hz., -6dB loss of SPL at 20 Hz., -12dB at 10 Hz. (these are octaves)
In ported designs, the Port Tuning Frequency (PTF) determines how low the sub will play and still be distortion free. When porting, we get a nice passive peak in bass near the PTF. That peak is about +3dB more than a sealed enclosure will deliver with same sub and same power input. So now, you have +128 dB of output VS the 125 dB we mentioned earlier.
Near the PTF, the cone produces very little audio. The sound comes from the port. The cone does not move very much at PTF as the back pressure in the enclosure is being released into the port. That means the lack of cone movement, reduces cooling of the voice coils. This is where a lot of subs get fried. Not much movement and loads of power being dissapated in the form of heat. That's what fries a sub coil.
Below PTF, the cone motion returns, but there is so little backpressure in the box, it cannot control the cone movements. Basically, this acts like there is no enclosure at all. (a "free air") sub is the result. With no control over the cone movement, the sub goes spastic and will often jump the gap or the coil bottoms out. Again, the result is a damaged sub.
When we use a SS filter, the filter will remove a goodly portion of sound energy that would normally pass to the woofer. The larger the slope of the filter, the better. Less watts of power (SPL) to the sub, below PTF is how we protect expensive woofers. The most efficient way to do this, is prior to amplification. That helps the amp as it does not waste large amounts of power, trying to amplify signals below PTF. In car audio, we don't get much music content below ~35-40 Hz. If PTF is say 40 Hz., we want to filter out as much signal content as possible, as we approach PTF. This is where good filtering is needed.
Let's say a sub is getting 300 watts of signal at 40 Hz. That's pretty loud stuff. Now, insert a 40 Hz SSF, 12dB/octave and the output watts will drop to (~20 watts) flowing to the sub at 20 Hz. That's safe for the sub to dissapate heat in that range. A 40 Hz SSF, 18dB/octave slope will lower the power to sub even more. Here, the sub is getting about 4.5 watts at 20 Hz. The basic line of designing a good filter, is to know that for each 3dB of sound we filter, it drops the watts input to the driver by 50%.
Here's a chart:
dB slope/octave........................................wattage to speaker
0dB reference...(no filtering).....................300 watts @ 40 Hz.
-3dB........................................................150 watts @ 20 Hz
-6dB.........................................................75 watts @ 20 Hz.
-9dB.........................................................37.5 watts @ 20 Hz.
-12dB.......................................................18.75 watts @ 20 Hz
-15dB....................................................... 9.38 watts @ 20 Hz.
-18dB....................................................... 4.7 watts @ 20 Hz.
See how that works? It's logrithmic, not linear.
We see this in sub amps VS mid/highs amps. Sub amps are much larger and produce large amounts of audio output. Mid/high amps are smaller and it takes many less watts to generate a +120dB signal to the mid/high speakers. (~60 watts will do) A sub needs more like 150 watts to get the same +120dB of SPL.
WOW... that's along winded explaination. But I hope it helps you and others that read this post. If you have more questions, will bo my best to answer them.
Swez
PS Most audio sales people and installers are just that.... installers and sellers. This is design and engineering type stuff. Don't expect them to know it, unless they have studied it in depth. I am not an Expert in this area, but I have studied it a while now. Hopefully this presentation of a very complex subject, is simple enough to learn and use. I'm trying my best... but it may still be too deep? Comments?
uochronos on 08/10/2004 02:44:20
wow Swez excelent explanation.... i think we need to put that in the DIY area because hoenstly i didnt even udnerstand it that incredibly well till i read that and now that i saw all the formula and what not it all makes wonderfull sense..
thats definatly a helpfull explanation. i think alot of people are confused about why you need an SS filter and this explanation helps alot.
P0werLifter on 08/10/2004 03:12:26
Bump, I agree that should be posted in the FAQ or DIY sections. In reading your post Swez that helped me understand why we need SS filters etc. GREAT EXPLANATION!!!!!!!!!! Sometimes things get to complicated for someone who is just starting/someone whos been learning to understand in one reading. GREAT Post
Thanks
Jason
swez on 08/10/2004 17:13:44
Thanks guys... I am waiting for LC1 to check in on this one too. If he got a handle on the topic, hit the target.
Will have to edit it down a bit too for FAQ/DIY ... too long.
Swez
LC1 on 08/11/2004 14:40:30
Swez,
Great post as I said before in the chat room. I went to Audiomagic yesterday and they had an older Hi-Fonics active crossover @35Hz -18dB . It was somthing he had from about 4 or 5 years ago he said and he sold it to me for $25CDN. This is a bit off topic but I actually found out that the guy who I was talkign to owns the shop and he lives four houses down from me and is friends with my parents lol. So now I know who to go to for anything else I may need. He even offered me an Alpine amp at cost as well, one they had in the back room and forgot about.
Anyways thanks for the great help swez & uochronos. Going to start building my sub box on the weekend. Just finished up my blueprints on the computer with Autodesk Inventor.
Actually do you guys mind taking a look at my drawings and make sure I have everything cover? (NOTE: There is no top pannel on the drawings.)
The pictures are here: http://www.pbase.com/lc1/vented_enclosure
Thank you very much,
Jason
LC1 on 08/11/2004 14:46:10
Also forgot to mention that the box is supposed to be 1.75 cu/ft with the port and sub displacement factored in. And the overall dimensions are located on the bottom left. The ones on the right are what to cut the pannels at.
http://www.pbase.com/lc1/vented_enclosure
Thanks again,
Jay
uochronos on 08/11/2004 15:25:06
look like a very well planned out box. and from the looks of it a very good design as well. it should net very good results
swez on 08/12/2004 18:38:30
Very well drawn and planned. This is more like a transmission line enclosure. Stronger low end bass and almost perfectly in phase outputs at cone and port. This is much better than average performance we get from most port tuned enclosures.
Just make sure you accounted for all the baffle panels displacement wise.
9.5" x 13.75" x 0.75" = 98.0 x 2.75 vent panels = 270.0 cu in. of port displacement + sub displacement # needs to be included in the gross internal airspace of this box. (or something pretty close to that)
Swez
LC1 on 08/13/2004 00:45:13
Just one more quick question on this topic. I heard that when a sub in a ported application distortion is harder to tell, is that right? So do I just adjust my gain/HU settings the same way and when I heard the sub distort just back off on the gain a bit?
Thanks,
Jay
P.S. After this weekend when I build my new enclosure I will let you know how it sounds.
P0werLifter on 08/13/2004 00:52:10
Very Nice Plans. Where did u find the program? Ive been looking for one like that.
~Jason
LC1 on 08/13/2004 01:14:27
P0werLifter,
I got this program from a co-op job that I was on last year. I am a Mechanical Engineering student and we use that for all kinds of engineering drawings. I don't know if it would be possible to send you a copy of it because it is a pretty big program. But the program is called Autodesk Inventor. My version is 5.3 but their up to 7.0 or 8.0 now. You may be able to find it online somewhere.
Jay
P0werLifter on 08/13/2004 01:42:51
Cool thanks Jay ill be lookin for it. Rebuilding my enclosure for my subs. 3.0 CuFt for each sub Tuned to 30hz
swez on 08/13/2004 07:52:02
Yes, gain setting is the same technique as mentioned before. However, power handling will be a tad less at lower frequencies as the PTF comes into play.
If you have a test tone CD, try it out below PTF and see how well the filter works on that amp.
Swez
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