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Author Topic: Replacement drivers for sub cabinets  (Read 7192 times)

Greg g. Pierce

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Replacement drivers for sub cabinets
« on: January 27, 2012, 12:29:08 PM »

I have been having trouble with some old PAS sub cabinets. Tim and Tim, have helped me through figuring out what might have caused me to have speaker troubles, I got that taken care of. Now, I pose this question to the Brain Trust. The original drivers are ORIGINAL, 25 to 30 years old, been reconed at least once already according to the writing on the back of the speaker. I cannot find a brand on the speakers. I do find a model # but can't bring up anything online anywhere as to what would be the same speaker, in another newer brand. The speakers are 18's with model # LR1880C , Serial #28329 , hand written on the back of the cone is the number 31843. 6-2-2002

The cabinets are trapezoid shaped 32" wide at the mouth/front, 16.5" wide at the back, 25.5" deep/sides, 48.5" tall, 1" inset on the front where the grill covers the speakers, they are front loaded, with a 3" vent port that runs the entire width of the front of the cabinet.

So, should I recone the old speakers, or is there a newer technology, of same specs, that would match the cabinets, that would be better?

Thanks for any guidance. I have talked to parts express, they say recone, a speaker repair service in Nashville says new speakers, I know we cant just drop anything in, done that, doesn't work. So....thoughts?

Posted in another thread below this one, is a picture of these old cabinets should anyone need to see what we are dealing with. Also, I have set the drpa to the settings suggested by Tim and Tim Mc.

Thanks again,
greg pierce
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Paul G. OBrien

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Re: Replacement drivers for sub cabinets
« Reply #1 on: January 27, 2012, 11:49:17 PM »

These are bass reflex cabs so they're not rocket science and other drivers will work, but in order to determine what ones will work best and/or what mods would need to be done to accomadate a better driver, you need to know the internal volume of the cabinet excluding space taken up by the ports and the port dimensions, and with that you can then determine what drivers are suitable replacements using a software program like WinISD Pro. Since these cabs are not a regular shape I'm gonna suggest you remove the drivers and take these measuremets yourself, and if you post that info here we can help with driver selection.
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Elliot Thompson

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Re: Replacement drivers for sub cabinets
« Reply #2 on: January 28, 2012, 06:34:50 AM »

Hi.

Your biggest challenge would be finding a loudspeaker that offers the same specs that will fit in your cabinet.

PAS 18-inch woofers are larger than average 18-inch woofer. I own one that was given to me decades ago and the driver measures 18 ½ inches. It may be best to just have the drivers re-coned if you do not want to go through the ordeal of finding divers that will not only fit your cabinets but offer similar specs as well.

The closest alternative (drop in the box) for the PAS 1880C would be the JBL 2441 or the 2268 with minor retuning of the cabinet. There are other brands that will work by either just dropping it in the cabinet or minor retuning. However, the JBL is the closest in terms of diameter to the PAS than other models.

Best Regards,

Elliot.
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Greg g. Pierce

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Re: Replacement drivers for sub cabinets
« Reply #3 on: January 28, 2012, 07:25:58 AM »

These are bass reflex cabs so they're not rocket science and other drivers will work, but in order to determine what ones will work best and/or what mods would need to be done to accomadate a better driver, you need to know the internal volume of the cabinet excluding space taken up by the ports and the port dimensions, and with that you can then determine what drivers are suitable replacements using a software program like WinISD Pro. Since these cabs are not a regular shape I'm gonna suggest you remove the drivers and take these measuremets yourself, and if you post that info here we can help with driver selection.
Thanks Paul, today I plan on taking all the drivers out, inspecting the cabinets for leaks, check wiring, test speakers out of the box, then put them back together. Since the speakers are currently mismatched, Im going to put the two like speakers in the same box while I figure out what to get to replace all speakers with. I will measure inside the box while I have them open.
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Greg g. Pierce

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Re: Replacement drivers for sub cabinets
« Reply #4 on: January 28, 2012, 07:31:29 AM »

Hi.

Your biggest challenge would be finding a loudspeaker that offers the same specs that will fit in your cabinet.

PAS 18-inch woofers are larger than average 18-inch woofer. I own one that was given to me decades ago and the driver measures 18 ½ inches. It may be best to just have the drivers re-coned if you do not want to go through the ordeal of finding divers that will not only fit your cabinets but offer similar specs as well.

The closest alternative (drop in the box) for the PAS 1880C would be the JBL 2441 or the 2268 with minor retuning of the cabinet. There are other brands that will work by either just dropping it in the cabinet or minor retuning. However, the JBL is the closest in terms of diameter to the PAS than other models.

Best Regards,

Elliot.
Thanks Elliot, I did notice that the two B52 speakers don't fit right. I didn't measure them to find out that was the problem. that's interesting. I will look into the JBLs. What kind of retuning needs to be done. Can you describe the process to me a little. I want to get these as good as I can get them to get through the rest of this year, then I think I am going to build me a set of the Lab Subs listed here on the forum. I have a complete woodshop and build furniture, jewelry boxes, etc for hobby, so that will be a fun project that I can use too.

Thanks for your diagnosis on the problem.
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Elliot Thompson

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Re: Replacement drivers for sub cabinets
« Reply #5 on: January 28, 2012, 03:25:27 PM »

Hi.

I am about to do an event so I will offer more information on Sunday. Retuning a bass reflex cabinet is merely extending or reducing the length of the vent(s). I will scale the cabinet so you can see the results using the PAS -versus- JBL.  However, I will require the port’s diameter and length of the enclosure.

Pending on your budget, it will be cheaper to just re-cone the PAS drivers than looking at raw JBL drivers considering you are looking to switch to lab-subs.

Best Regards,

Elliot.
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Sndguy (Joel Ashcraft)

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Re: Replacement drivers for sub cabinets
« Reply #6 on: January 28, 2012, 07:08:42 PM »

Greg
Those 1880's are originally 200w (400w peak), and are larger. We used to have a bunch of these (1994-5). They worked ok in those cabs, but once you get the LABs together, you'll be glad you switched.

We ended up putting evx180s in ours for a while, before going to something else.   Those cabinets were a staple in the club circuit back then, though, as it gave us a decent place to stack tops on.

Let me know if you need more info, I might be able to dig some up. 

Joel


I have been having trouble with some old PAS sub cabinets. Tim and Tim, have helped me through figuring out what might have caused me to have speaker troubles, I got that taken care of. Now, I pose this question to the Brain Trust. The original drivers are ORIGINAL, 25 to 30 years old, been reconed at least once already according to the writing on the back of the speaker. I cannot find a brand on the speakers. I do find a model # but can't bring up anything online anywhere as to what would be the same speaker, in another newer brand. The speakers are 18's with model # LR1880C , Serial #28329 , hand written on the back of the cone is the number 31843. 6-2-2002

The cabinets are trapezoid shaped 32" wide at the mouth/front, 16.5" wide at the back, 25.5" deep/sides, 48.5" tall, 1" inset on the front where the grill covers the speakers, they are front loaded, with a 3" vent port that runs the entire width of the front of the cabinet.

So, should I recone the old speakers, or is there a newer technology, of same specs, that would match the cabinets, that would be better?

Thanks for any guidance. I have talked to parts express, they say recone, a speaker repair service in Nashville says new speakers, I know we cant just drop anything in, done that, doesn't work. So....thoughts?

Posted in another thread below this one, is a picture of these old cabinets should anyone need to see what we are dealing with. Also, I have set the drpa to the settings suggested by Tim and Tim Mc.

Thanks again,
greg pierce
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Stu McDoniel

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Re: Replacement drivers for sub cabinets
« Reply #7 on: January 28, 2012, 08:58:19 PM »

I have been having trouble with some old PAS sub cabinets. Tim and Tim, have helped me through figuring out what might have caused me to have speaker troubles, I got that taken care of. Now, I pose this question to the Brain Trust. The original drivers are ORIGINAL, 25 to 30 years old, been reconed at least once already according to the writing on the back of the speaker. I cannot find a brand on the speakers. I do find a model # but can't bring up anything online anywhere as to what would be the same speaker, in another newer brand. The speakers are 18's with model # LR1880C , Serial #28329 , hand written on the back of the cone is the number 31843. 6-2-2002

The cabinets are trapezoid shaped 32" wide at the mouth/front, 16.5" wide at the back, 25.5" deep/sides, 48.5" tall, 1" inset on the front where the grill covers the speakers, they are front loaded, with a 3" vent port that runs the entire width of the front of the cabinet.

So, should I recone the old speakers, or is there a newer technology, of same specs, that would match the cabinets, that would be better?

Thanks for any guidance. I have talked to parts express, they say recone, a speaker repair service in Nashville says new speakers, I know we cant just drop anything in, done that, doesn't work. So....thoughts?

Posted in another thread below this one, is a picture of these old cabinets should anyone need to see what we are dealing with. Also, I have set the drpa to the settings suggested by Tim and Tim Mc.

Thanks again,
greg pierce
Hey Greg how bout we do a physical check on those drivers.  Simply remove the drivers
and set one on the table.  Take your hands on either side of the cone and physically move the cones up and down to xmax with your hands/fingers being very careful to keep the movement
even.  Do you hear any rubbing of the former (voice coil is wrapped on the former) on the magnet
pole piece? If you hear rubbing there is your problem and recone /replace. If you are moving the cone up and down to max and there is no rubbing sound you probably are ok.   Keep in mind when a loudspeaker gets pounded on for many years the suspension and web tend to kind of wear out and I have seen this exact thing you are describing.
Basically the only alternative is to recone or replace.   Simply get the internal volume of your cabs
and Emminence makes nice loudspeakers like the KILO max you can load up in those cabs and
keep it affordable. 
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Greg g. Pierce

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Re: Replacement drivers for sub cabinets
« Reply #8 on: January 29, 2012, 08:40:07 AM »

Hey Greg how bout we do a physical check on those drivers.  Simply remove the drivers
and set one on the table.  Take your hands on either side of the cone and physically move the cones up and down to xmax with your hands/fingers being very careful to keep the movement
even.  Do you hear any rubbing of the former (voice coil is wrapped on the former) on the magnet
pole piece? If you hear rubbing there is your problem and recone /replace. If you are moving the cone up and down to max and there is no rubbing sound you probably are ok.   Keep in mind when a loudspeaker gets pounded on for many years the suspension and web tend to kind of wear out and I have seen this exact thing you are describing.
Basically the only alternative is to recone or replace.   Simply get the internal volume of your cabs
and Emminence makes nice loudspeakers like the KILO max you can load up in those cabs and
keep it affordable.
Thanks for the info Stu,
I don't hear anything. I took the speakers out yesterday and tested each with a 9v battery, they jump like they are supposed to. Put them back in, tightened them up. Thought the bbrraaapp noise was gone, but I can still get it but under increasingly high volume. I'm now thinking that the 4 clamps that hold the speaker in place may not be enough. I'm going to put some more clamps on all the speakers and try again. I think Im closing in on it.
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Stu McDoniel

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Re: Replacement drivers for sub cabinets
« Reply #9 on: January 29, 2012, 10:03:04 AM »

Thanks for the info Stu,
I don't hear anything. I took the speakers out yesterday and tested each with a 9v battery, they jump like they are supposed to. Put them back in, tightened them up. Thought the bbrraaapp noise was gone, but I can still get it but under increasingly high volume. I'm now thinking that the 4 clamps that hold the speaker in place may not be enough. I'm going to put some more clamps on all the speakers and try again. I think Im closing in on it.
Simply putting a 9vdc battery across the terminals is not going to reveal slight rubbing
of the former on the pole piece Greg.   You have to pull the loudspeaker and place your fingers under the cone and push up to xmax and then let the cone fall back into place and slightly push down on the cone.  Macke absolutely certain you keep the cone movement even when you pull the cone up in the gap.  Any slight rubbing (you will feel it) deams a recone/replacement.
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ProSoundWeb Community

Re: Replacement drivers for sub cabinets
« Reply #9 on: January 29, 2012, 10:03:04 AM »


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