Got_Horns Posted February 21, 2023 Share Posted February 21, 2023 Has anyone tried this? I have t500s with a passive radiator. I was also thinking about my klf20s....when in a moment of pure genius or absolute foolishness. I thought about swapping the passive for an active sub. Making, a sort of, mini klf30. I'm planning on redoing the cabinets anyways. Maybe run a minidsp for the crossover? Just thinking out loud..... 1 Link to comment Share on other sites More sharing options...
moray james Posted February 21, 2023 Share Posted February 21, 2023 if you mean that you want to remove the passive radiator in your T500,s then bock off the open hole and run the T500 as a sealed cabinet and augment the low bass with and active (powered) sub then sure I would say that was a good idea. But if you are suggesting that you remove the passive radiator from the T500 then install a second woofer into where the passive was and run it in either parallel or series with the existing woofer then no that would be a non productive thing to do since you would need to re design your speaker to make such an idea work, it is just not a useful way for you to spend your time or money. In case you are not sure about what a passive radiator does it has the exact same function as a reflex vent in that it is a resonating mass which couples in antiphase to the woofer to provide damping/control to the woofer when it plays low enough to reach the system resonance. It is like an acoustical break which is frequency controlled it couples with the woofer adding a mass to the woofer which then alters (lowers) the resonant frequency of the woofer. This process happens over a very narrow band of frequency of only 5 or 6 Hz. and without it to damp or control the woofer it would reach the system resonant point and begin to resonate at full excursion and if left undamped would proceed to tear itself to pieces. I hope this helps you to understand things a little better. If you want more bass add a sub or two. removing the passive and blocking it off with a plywood blank would turn your speakers into a sealed box design. A reflex box whether it is designed with a vent or a passive radiator has a roll off of 24 db per octave below the tuning frequency while a sealed box rolls off at only 12db per octave below system or box resonance, so you will actually get lower frequency extension and more useful output with the box sealed. This would involve re damping the cabinet. There is a caveat and that is that almost all reflex designs have an intentional hump in the bass response somewhere prior to system or box resonance this is intended to make the woofer provide a little more umph. With a sealed box you will loose the additional bass hump in the response but since it rolls off so much slower you will attain lower bass frequency extension. There is no "free lunch" you decide what you want to achieve. Good of you to ask your question because you are not the only person to have wondered about this. The more questions you ask the more you will know and hopefully the easier your audio journey will be. Remember the fun is in the journey and not the destination. 2 3 Link to comment Share on other sites More sharing options...
JohnA Posted February 23, 2023 Share Posted February 23, 2023 A passive radiator is a substitute for a resonant port. It has the advantage of also limiting the woofer's travel below resonance (protecting the woofer from very low bass notes). Do not change or modify it. Do not remove it, the cabinet volume is sized to use a passive radiator and will probably be too big for the woofer if you remove it. Adding a second active woofer will require a cabinet with double the volume of one with a single woofer. If you want deeper bass, add a good subwoofer (sound lower/under a woofer). If you want louder bass, move them closer to a corner or add EQ. 2 Link to comment Share on other sites More sharing options...
OO1 Posted February 23, 2023 Share Posted February 23, 2023 go for it , you wont know until you try it ..... T-500 cabinet would have to be re-enforced and the height extended by 5 inches to match the KLF-30 dimensions , the rest is pretty much the same as far as the depth and width . 2 Link to comment Share on other sites More sharing options...
Got_Horns Posted February 23, 2023 Author Share Posted February 23, 2023 4 hours ago, OO1 said: go for it , you wont know until you try it ..... T-500 cabinet would have to be re-enforced and the height would have to be extended by 5 inches to match the KLF-30 dimensions , the rest is pretty much the same as far as the depth and width . That's the spirit!! Onward and upward! What model woofer should I be looking for? I'm going to be using a community shop. So I'm trying to do everything at once. I need to deaden and brace my klf20s. And remake the t500 cabinets. Would be very easy to make them klfs. Since I will have real klfs there to take measurements off of. What wood should I make them out of? Birch ply? 1 Link to comment Share on other sites More sharing options...
Got_Horns Posted February 23, 2023 Author Share Posted February 23, 2023 On 2/21/2023 at 6:05 AM, moray james said: if you mean that you want to remove the passive radiator in your T500,s then bock off the open hole and run the T500 as a sealed cabinet and augment the low bass with and active (powered) sub then sure I would say that was a good idea. But if you are suggesting that you remove the passive radiator from the T500 then install a second woofer into where the passive was and run it in either parallel or series with the existing woofer then no that would be a non productive thing to do since you would need to re design your speaker to make such an idea work, it is just not a useful way for you to spend your time or money. In case you are not sure about what a passive radiator does it has the exact same function as a reflex vent in that it is a resonating mass which couples in antiphase to the woofer to provide damping/control to the woofer when it plays low enough to reach the system resonance. It is like an acoustical break which is frequency controlled it couples with the woofer adding a mass to the woofer which then alters (lowers) the resonant frequency of the woofer. This process happens over a very narrow band of frequency of only 5 or 6 Hz. and without it to damp or control the woofer it would reach the system resonant point and begin to resonate at full excursion and if left undamped would proceed to tear itself to pieces. I hope this helps you to understand things a little better. If you want more bass add a sub or two. removing the passive and blocking it off with a plywood blank would turn your speakers into a sealed box design. A reflex box whether it is designed with a vent or a passive radiator has a roll off of 24 db per octave below the tuning frequency while a sealed box rolls off at only 12db per octave below system or box resonance, so you will actually get lower frequency extension and more useful output with the box sealed. This would involve re damping the cabinet. There is a caveat and that is that almost all reflex designs have an intentional hump in the bass response somewhere prior to system or box resonance this is intended to make the woofer provide a little more umph. With a sealed box you will loose the additional bass hump in the response but since it rolls off so much slower you will attain lower bass frequency extension. There is no "free lunch" you decide what you want to achieve. Good of you to ask your question because you are not the only person to have wondered about this. The more questions you ask the more you will know and hopefully the easier your audio journey will be. Remember the fun is in the journey and not the destination. Thanks. My plan was to remove the passive and put in an active woofer. And either run it active crossover with say a minidsp or get some passive crossovers. I know I have to make the cabinets bigger, I need to rebuild them anyway, so not a big deal. Link to comment Share on other sites More sharing options...
Got_Horns Posted February 23, 2023 Author Share Posted February 23, 2023 4 hours ago, JohnA said: A passive radiator is a substitute for a resonant port. It has the advantage of also limiting the woofer's travel below resonance (protecting the woofer from very low bass notes). Do not change or modify it. Do not remove it, the cabinet volume is sized to use a passive radiator and will probably be too big for the woofer if you remove it. Adding a second active woofer will require a cabinet with double the volume of one with a single woofer. If you want deeper bass, add a good subwoofer (sound lower/under a woofer). If you want louder bass, move them closer to a corner or add EQ. I am running a 15" sub with them now. The t500 cabinets are beat to crude and no longer sealed. Instead of patching and such. I'd rather build new ones. So making them bigger is not a big deal. This way, I can deaden and overbuild them. As this is in my nature. If I'm going to do something, I'm going to over do it....I'm also the, while I'm in there guy.. Link to comment Share on other sites More sharing options...
OO1 Posted February 23, 2023 Share Posted February 23, 2023 50 minutes ago, Got_Horns said: What wood should I make them out of? Birch ply? ideal woofers , klipsch K-28 or the K-281 4 Ohms - - Birch ply , or ApplePly , or MDF with machine screws and T-Nuts . 1 Link to comment Share on other sites More sharing options...
avguytx Posted February 23, 2023 Share Posted February 23, 2023 So you're talking about adding a woofer with it's own amp in that location where the passive was and sharing the same air space as the other woofer that will be tied in to a different amp? Absolute foolishness is what I would call it...being nice. Just add a sub and call it good. But, if you go ahead and do them in the same cabinet, at the least put the woofers in SEPARATE chambers. 2 1 Link to comment Share on other sites More sharing options...
Got_Horns Posted February 23, 2023 Author Share Posted February 23, 2023 4 minutes ago, avguytx said: So you're talking about adding a woofer with it's own amp in that location where the passive was and sharing the same air space as the other woofer that will be tied in to a different amp? Absolute foolishness is what I would call it...being nice. Just add a sub and call it good. But, if you go ahead and do them in the same cabinet, at the least put the woofers in SEPARATE chambers. Adding another chamber is easy....I'm talking about essentially turning the t500 into a klf30. And making entirely new cabinets. Having it on an active network or getting a crites klf crossover kit. Link to comment Share on other sites More sharing options...
Got_Horns Posted February 23, 2023 Author Share Posted February 23, 2023 26 minutes ago, OO1 said: ideal woofers , klipsch K-28 or the K-281 4 Ohms - - Birch ply , or ApplePly , or MDF with machine screws and T-Nuts . I'm guessing the birch would be better having less resonance than the mdf? Link to comment Share on other sites More sharing options...
avguytx Posted February 23, 2023 Share Posted February 23, 2023 On 2/23/2023 at 5:01 PM, Got_Horns said: Adding another chamber is easy....I'm talking about essentially turning the t500 into a klf30. And making entirely new cabinets. Having it on an active network Ok, so IF you do it where it's like a KLF-20/30, so to speak, they could share cabinet volume BUT there's more that goes into it than just putting two woofers in a cabinet made from nice wood and good bracing, then working out the port tuning frequency, then building the networks to be "in tune" with the speakers as a whole, etc. I guess if you're just shooting from the hip and whatever happens happens, it's all in good fun. Typically that's where you need the T/S parameters of the woofers to find the right cabinet volume and tuning using various programs. Good luck. 1 Link to comment Share on other sites More sharing options...
avguytx Posted February 23, 2023 Share Posted February 23, 2023 3 minutes ago, Got_Horns said: Yes, that is where I need help with the tuning. But if I match the klf cabinets and drivers ...put a crites klf xover in it... .I know I need to port(front firing). The rear port is the only thing I don't like about the real klfs. But use the same port hole size...then it should be close or the same as the klfs? I'm not seeing a big problem here. Making the cabinets is easy for me. I was an car installer, that used to compete. I have made tons of boxes. Most custom fiberglass. I have been in the building trades most of my life. From framing to finish to metal fabrication to machining. I can build pretty much anything to very high tolerances and standards. Yeah, I did car audio from 1983 till 2009, when I got out of the industry; the last 8 years I was a manufacturers rep for Rockford, Lightning Audio, MBQ, Q-Logic, Clarion, and some others. Was a fun time but glad to be out of that industry. lol Also did home A/V in retail and as a rep for many lines, of course. I don't have any tools to help with the tuning and I don't know if the T/S parameters are even out there to do use. Not to mention, anymore, Klipsch doesn't really think highly of their speakers being "redone" and they sometimes drop threads here. Maybe that's more with the Heritage since that's still current and not so much on things like Tangent, Epic, KLF, etc, But who knows. There are other forums where you can freely discuss these things without fear of deletion. 1 Link to comment Share on other sites More sharing options...
Got_Horns Posted February 23, 2023 Author Share Posted February 23, 2023 Sorry if the thread has been confusing. In the OP I was thinking of just replacing the passive with an active woofer and drilling a port. But after realizing all that would need to be done. I might as well make a new cabinet and duplicate a klf30. Especially since the t500 cabinets are in such bad shape. I can still find out if the original idea would have worked. Once I get the woofers delivered. Link to comment Share on other sites More sharing options...
Got_Horns Posted February 24, 2023 Author Share Posted February 24, 2023 7 minutes ago, avguytx said: Yeah, I did car audio from 1983 till 2009, when I got out of the industry; the last 8 years I was a manufacturers rep for Rockford, Lightning Audio, MBQ, Q-Logic, Clarion, and some others. Was a fun time but glad to be out of that industry. lol Also did home A/V in retail and as a rep for many lines, of course. I don't have any tools to help with the tuning and I don't know if the T/S parameters are even out there to do use. Not to mention, anymore, Klipsch doesn't really think highly of their speakers being "redone" and they sometimes drop threads here. Maybe that's more with the Heritage since that's still current and not so much on things like Tangent, Epic, KLF, etc, But who knows. There are other forums where you can freely discuss these things without fear of deletion. Luckily the community shop has a lot of HiFi guys there. With all the software and testing devices. I hope? It has to be close, if I can make a exact replica of the klf? Anyways, once I get the new woofers, we shall see! What's cool is that I have a A/B receiver and the pair of klf 20s. Should be fun to do side by side comparisons. Link to comment Share on other sites More sharing options...
Got_Horns Posted February 24, 2023 Author Share Posted February 24, 2023 8 hours ago, OO1 said: ideal woofers , klipsch K-28 or the K-281 4 Ohms - - Birch ply , or ApplePly , or MDF with machine screws and T-Nuts . I'm having trouble finding the k28. Could I use the k28e? Or where would one find a k28, k281? Link to comment Share on other sites More sharing options...
jjptkd Posted February 24, 2023 Share Posted February 24, 2023 3 hours ago, Got_Horns said: I'm having trouble finding the k28. Could I use the k28e? Or where would one find a k28, k281? If you're building new cabinets to KLF-30 specs and using those crossovers you should consider the Ciare woofers lots of people have swapped them out in their 30's with good results: https://www.usspeaker.com/ciare-hw321-1.htm 1 Link to comment Share on other sites More sharing options...
OO1 Posted February 24, 2023 Share Posted February 24, 2023 9 hours ago, Got_Horns said: I'm having trouble finding the k28. Could I use the k28e? Or where would one find a k28, k281? klipsch Parts sell the k-28-E + the K-281 same with https://reconingspeakers.com/ , but klipsch Parts is much cheaper BTW check these out ...in LA , https://www.ebay.com/itm/255989095714?hash=item3b9a239d22:g:MqIAAOSwQQNj9wvF 1 Link to comment Share on other sites More sharing options...
Got_Horns Posted February 24, 2023 Author Share Posted February 24, 2023 7 hours ago, OO1 said: klipsch Parts sell the k-28-E + the K-281 same with https://reconingspeakers.com/ , but klipsch Parts is much cheaper BTW check these out ...in LA , https://www.ebay.com/itm/255989095714?hash=item3b9a239d22:g:MqIAAOSwQQNj9wvF Those are nice cabinets. But that takes away all my fun 😊. I'm now thinking of making something totally unique. I'm curious on how much internal air volume the mid horn and tweet horn need? Link to comment Share on other sites More sharing options...
Got_Horns Posted February 24, 2023 Author Share Posted February 24, 2023 Thinking of a woofer chamber, then getting artsy on the mids and tweets. Something like the picture but different. Link to comment Share on other sites More sharing options...
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