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jbldriven
03-06-2006, 08:37 PM
I have a set of 2245h in mint condition purchased in the original boxes sealed 3 months ago. I have run the woofers in loaded horn cabinets from bentwood. I am using Bryston 4b in mono block to drive each sub. Bryston claims the 4 B puts out 800 watts into 8 ohms strapped. The JBl woofer is rated at 600 watts continuous pink noise. The cone started to separate from the voice coil approximately 1/8 around diameter. I had a jbl dealer remove the dust cap and recement the voice coil. When the dust cap was off the repair tech said the coil showed evidence of slight over heating. I seen the apparent discolouring on the coil ( not that i have seen an original coil to compare ) and wished i had take a picture to verify. The recementing seems to worked fine. I have a couple of questions to be answered.
1. Could there be a faulty glue connection which caused the seperation?
2. I checked out the JBL Pro Vintage section and I am not shure what this woofer is rated for. The Theile parameters are 300 watts contiuous sine wave and the jbl vebage says 600 watts Pink noise. Can someone tell me what the RMS wattage rate is before they melt down.
3. If the wattage rating is 300 watts what should i replace the 2245's with. I need a driver that has a low resonence 25 hz. . These cabinet reproduce down to 20 hz and lower, no problem.

I am using altec 416 8b mid bass loaded bentwood horn, JBL2482 bentwood mid horn and JBL2410 with 2301 masher on highs - controlled with a JBL DSC 280 crossover. Parasound six channel amp (80 watts per channel) driving each driver from the mid bass to high. and two bryston 4b's on sub bass.

Mr. Widget
03-07-2006, 01:06 AM
The 2245H is a wonderful woofer that was designed before today's extreme bass and power levels were anticipated. You are obviously over driving the woofer... don't take it personally, movie theaters and pro sound companies across America ran into this problem and have switched over to the newer 2242H. It is also what JBL now supplies in their top of the line Synthesis systems. The 2242H can handle significantly more power and abuse. It also has less dynamic compression (the loss of SPLs as the driver heats up) so it will play more loudly after 30 minutes than most other woofers of similar power and sensitivity ratings.


Widget

Mike Caldwell
03-07-2006, 06:16 AM
Hello
Are you using a high pass filter on the the subs to prevent over excursion of the speakers from sub low frequencies. You should ba able to program it in the 280. I would suggest 25hz.

Mike Caldwell

gene
03-07-2006, 07:59 AM
hello. can the 2242h cone be install in the 2245h frame. also I had my crossover custom built from dss sound labs I have 2245h/2202h/2425h/2404h the crossover freq is 200-1200-5000 and has a 95 db at 1 watt . what do I have to change in the crossover to bring every thing up to 99 db at 1 watt. the jbl 2245h is 95 db at 1 watt and the 2242h is 99 db at 1 watt:blink:

Robh3606
03-07-2006, 08:25 AM
can the 2242h cone be install in the 2245h frame.

Simply no. Different gaps and motors.



what do I have to change in the crossover to bring every thing up to 99 db at 1 watt.

On an electronic crossover??? You can adjust the gain on the drivers or overall for the channel. That's artificial. You can't change the basic driver effciency unless you horn load or in the bass or you get the drivers to couple which adds 6DB and room gain which is variable and frequency dependant. Other than that, unless I missed something that is set in stone.

Rob:)

gene
03-07-2006, 08:45 AM
Thanks Robh 3606 for the info on the woofer. my crossover is passive

jbldriven
03-07-2006, 08:02 PM
I still haven't found out what the correct RMS wattage rating is on the 2245h. Will it take 600 watts rms

Robh3606
03-07-2006, 08:08 PM
Use the data sheet here:

http://www.jblpro.com/pages/components/2245h.htm

No if you look they define the 600 continuous music and 3dB above the sine/RMS so it's a 300 watt woofer which is probably what the T/S has it specified at with PE.

Rob:)

jbldriven
03-07-2006, 08:11 PM
Hello
Are you using a high pass filter on the the subs to prevent over excursion of the speakers from sub low frequencies. You should ba able to program it in the 280. I would suggest 25hz.

Mike Caldwell

I tried that and seem to loose the Kick drum punch. I tried rolling off at24 db per octive at 21 hert. I believe that my problem originated from Rap play by a younger family member during a party. I should have eq'd out some bass as his music is extremely bassy. The jbl dealer agreed this may have been the cause, possibly even from Suare wave effects used in rapp. I preffer regular music rather than rapcrap. Kids today you gotta loveem

jbldriven
03-07-2006, 08:14 PM
The 2245H is a wonderful woofer that was designed before today's extreme bass and power levels were anticipated. You are obviously over driving the woofer... don't take it personally, movie theaters and pro sound companies across America ran into this problem and have switched over to the newer 2242H. It is also what JBL now supplies in their top of the line Synthesis systems. The 2242H can handle significantly more power and abuse. It also has less dynamic compression (the loss of SPLs as the driver heats up) so it will play more loudly after 30 minutes than most other woofers of similar power and sensitivity ratings.


Widget

What is the power rating for 2245 ---600watts rms

Mike Caldwell
03-07-2006, 09:41 PM
Normally a high pass filter will actually tighten up a system by reducing cone over excursion and by preventing the power amp from wasting power trying to amplify frequencies outside of the speakers design. Most kick drum thump/punch is in the 50hz to 70hz range. In most music there is not much in the area around 20hz. Special effects, synthesizers, true pipe organ recordings can be the exception. I think the low B on a bass guitar is only something like 32hz. I'm not familiar with your speakers but how do they state the 20hz rating, many are not flat down to their low end cut off but are rated to say -3db at 20hz some will even rate them at a lower db level cut off per a given frequency.


Mike Caldwell

Mr. Widget
03-07-2006, 10:39 PM
What is the power rating for 2245 ---600watts rmsNo, as Rob said it is 600 watts program... 300 watts rms. The 2242 is 800 watts rms, and has greater sensitivity.


Widget

Ian Mackenzie
03-08-2006, 12:04 AM
I am surprised about the thermal damage, it could be from a previous user.
or possibly your amp is bleeding dc into the driver but that is unlikely

Even with 800 watts, that is well within the dynamic capability of these woofers according to Greg Timbers original 2245 subwoofer article. If you are attempting to use it for Pro sound reinforcement they might be unsuitable.

You might also check the tuning of the boxes, they should be tuned b/n 28-30 hertz for the 2245. I have never heard of horn loading the 2245 if I ead your post correctly!

Ian

norealtalent
03-08-2006, 04:12 AM
I recently purchased 10 identical factory JBL kits and 8 of 10 had faulty glue joints at the cone to coil former. There were many large gaps where the glue didn't touch one or the other. The two good ones were NOS, the 8 bad were freshly ordered. What does that say for anything else coming out their doors nowadays? I know mistakes happen but 100% garbage is inexucesable for any reason. They should never have made it by QC and the fact that they did is indicative of quality being sacrificed for the bottom line.

Maron Horonzakz
03-08-2006, 07:45 AM
When you let the bean counters take over a company the quality always goes down.

A Vanderkruk
03-08-2006, 07:52 AM
I have some 2245h as well with separated voice coils, is there a good aftermarket kit avaiable?
Andrew

jbldriven
03-08-2006, 06:59 PM
Use the data sheet here:

http://www.jblpro.com/pages/components/2245h.htm

No if you look they define the 600 continuous music and 3dB above the sine/RMS so it's a 300 watt woofer which is probably what the T/S has it specified at with PE.

Rob:)

Thanks Rob

jbldriven
03-08-2006, 07:17 PM
Normally a high pass filter will actually tighten up a system by reducing cone over excursion and by preventing the power amp from wasting power trying to amplify frequencies outside of the speakers design. Most kick drum thump/punch is in the 50hz to 70hz range. In most music there is not much in the area around 20hz. Special effects, synthesizers, true pipe organ recordings can be the exception. I think the low B on a bass guitar is only something like 32hz. I'm not familiar with your speakers but how do they state the 20hz rating, many are not flat down to their low end cut off but are rated to say -3db at 20hz some will even rate them at a lower db level cut off per a given frequency.


Mike Caldwell The dsc 280 can only be set by max 24 db per octive. It doesn't have a high pass filter, unless i am wrong. As for the response i will have to reffer you to Bentwood for the data. They will be coming to complete the real time anylis for phase alignment, offset and response measurements, with in the next coulple of days , I can post the results. The cabinets do produce extreme lows which can be heard in the brick house next to my detatched brick "play room". My wife doen't like when you interfer with the tv sound.

jbldriven
03-08-2006, 07:35 PM
I am surprised about the thermal damage, it could be from a previous user.
or possibly your amp is bleeding dc into the driver but that is unlikely

Even with 800 watts, that is well within the dynamic capability of these woofers according to Greg Timbers original 2245 subwoofer article. If you are attempting to use it for Pro sound reinforcement they might be unsuitable.

You might also check the tuning of the boxes, they should be tuned b/n 28-30 hertz for the 2245. I have never heard of horn loading the 2245 if I ead your post correctly!

Ian Yes they are horn loaded. The cabinet is designed for the 2245 T/s parameters. As for the amps they are 16 year old Bryston 4bs on monoblock. I live west of toronto and had to tend to buisness in area of Bryston Plant. I took the amps in for a check up today as they have a 20 year warr. I arrived at the plant at 7:30 am to be greeted by Cam the service manager. Cam gave me a grand tour. Everthing is hand built by personnel that care about the product. I spoke to some of the employees and sensed a really estatic workforce. The management obviously is do some right resulting in a product the evryone is proud of, including the consumer. I purchased the 3 amps used 1 year ago. They ran theme thru there testing program and the reults are still up to the original requirement. They even hooked up my Parasound HCA rated at116 or 118 db signal to noise to find out each channel was performong at 95 to 98 db. The para has a 60 hz bzz that i can't seem to get rid of.
I hope i can sleep tonight. I know i'll be dreaming of 3 more brystons to replace my Parasound.

jbldriven
03-08-2006, 07:39 PM
I recently purchased 10 identical factory JBL kits and 8 of 10 had faulty glue joints at the cone to coil former. There were many large gaps where the glue didn't touch one or the other. The two good ones were NOS, the 8 bad were freshly ordered. What does that say for anything else coming out their doors nowadays? I know mistakes happen but 100% garbage is inexucesable for any reason. They should never have made it by QC and the fact that they did is indicative of quality being sacrificed for the bottom line.

Thanks for the information. I wish i took a digital picture when the dust cap was off to show you what the discolouration was. I have no idea what a correct colour is for the voice coil. Is it possible that you could post the picture of a virgin coil. Thanks

jbldriven
03-08-2006, 08:07 PM
I Have a HCA 1206 80 watt six channel amp. I have cleaned the output relays and checked the solder joints . There still is a 60 herz buzz coming from my horns similar to the sound emited from a flourescence light. The sound doesn't get loader with volume. Parasound wants me to send it 3000 miles. Tried cheater plugs, grounding, different outlet with no success. It is sometinghing in the power supply. I had the unit hooked up at the bryston plant and the signal to noise was 95 to 98 db in the six channels which is substaintially worse than the 116 on there spec. I have disconnected the inputs and the buzz was still there. :bouncy: Is there a common problem with these amps. People have mentioned a problem with the transformer mounting but can't tell me the fix.:bouncy: Will i have to try a rope on for fishing:(

Mike Caldwell
03-08-2006, 08:35 PM
The high pass filtering can be applied in the EQ section by selecting the type of filter you want for a certain frequency. You would want a "shelf" filter.


Mike Caldwell

scott fitlin
03-08-2006, 08:49 PM
I Have a HCA 1206 80 watt six channel amp. I have cleaned the output relays and checked the solder joints . There still is a 60 herz buzz coming from my horns similar to the sound emited from a flourescence light. The sound doesn't get loader with volume. Parasound wants me to send it 3000 miles. Tried cheater plugs, grounding, different outlet with no success. It is sometinghing in the power supply. I had the unit hooked up at the bryston plant and the signal to noise was 95 to 98 db in the six channels which is substaintially worse than the 116 on there spec. I have disconnected the inputs and the buzz was still there. :bouncy: Is there a common problem with these amps. People have mentioned a problem with the transformer mounting but can't tell me the fix.:bouncy: Will i have to try a rope on for fishing:(Power supply de-coupling capacitors! I had one let go, the little ceramic disc caps that filter all the power supply noise over to ground, exactly what I heard, BZZZZZZZZ.

JBLGUY
03-08-2006, 09:17 PM
Hey JBLdriven....maybe that hum is coming from your pants......i've seen your type before in truck stops and bathrooms.

unplug your underwear

:shock: :wtf:

jbldriven
03-09-2006, 02:50 PM
The high pass filtering can be applied in the EQ section by selecting the type of filter you want for a certain frequency. You would want a "shelf" filter.


Mike CaldwellThanks i'll read the manual and give it a try.

jbldriven
03-09-2006, 02:54 PM
Hey JBLdriven....maybe that hum is coming from your pants......i've seen your type before in truck stops and bathrooms.

unplug your underwear

:shock: :wtf:What your talking about is a serious problem. The above mention problem results in deeper bass than most speakers can produce.

jbldriven
03-09-2006, 02:55 PM
Power supply de-coupling capacitors! I had one let go, the little ceramic disc caps that filter all the power supply noise over to ground, exactly what I heard, BZZZZZZZZ.. How was you problem deteched

scott fitlin
03-09-2006, 03:21 PM
. How was you problem detechedI had a crossover that had a really bad buzzing sound. Very loud 60hz type sound, BUUZZZZZZ! This shouldnt be! Checked everything, found nothing, took it to a tech, he found the problem. replaced faulty cap, no more noise.

jbldriven
03-09-2006, 05:46 PM
I had a crossover that had a really bad buzzing sound. Very loud 60hz type sound, BUUZZZZZZ! This shouldnt be! Checked everything, found nothing, took it to a tech, he found the problem. replaced faulty cap, no more noise.The crossover was electronic correct? I am shure the buzz is in the parasound not the DSC 280.

scott fitlin
03-09-2006, 05:57 PM
The crossover was electronic correct? I am shure the buzz is in the parasound not the DSC 280.Yeah, active electronic xover. BUT, the noise you describe could be PS decoupling caps gone bad, cold solder joint, broken lead, etc!

These caps are used to filter PS noise over to ground, and if you had one that wasnt doing its job, you would hear loud 60hz buzz.

Im thinking this could be the problem with your amp.

jbldriven
03-09-2006, 06:06 PM
Thanks i'll read the manual and give it a try.

Can't find the seting in the eq. Can you give more dtails for finding the shelf function. Taht is for the dsc280

jbldriven
03-09-2006, 07:05 PM
Yeah, active electronic xover. BUT, the noise you describe could be PS decoupling caps gone bad, cold solder joint, broken lead, etc!

These caps are used to filter PS noise over to ground, and if you had one that wasnt doing its job, you would hear loud 60hz buzz.

Im thinking this could be the problem with your amp. The problem willbe finding a tech locally i can trust

Mr. Widget
03-09-2006, 08:47 PM
The crossover was electronic correct? I am shure the buzz is in the parasound not the DSC 280.Easy enough to figure out. Disconnect the input from your amps. No noise... the problem is up stream... still have noise, there's your problem.


Widget

stevem
03-10-2006, 11:44 AM
Can't find the seting in the eq. Can you give more dtails for finding the shelf function. Taht is for the dsc280

If I understand correctly, this is not in the EQ section, but in the crossover section. You want to set the woofers with a lower crossover (high pass) point of 15 to 18 Hz, and then choose a slope. Start out with 12 db/octave and see what you like.

jbldriven
03-10-2006, 08:35 PM
If I understand correctly, this is not in the EQ section, but in the crossover section. You want to set the woofers with a lower crossover (high pass) point of 15 to 18 Hz, and then choose a slope. Start out with 12 db/octave and see what you like. If i understand you correctly that is the current configuration that i'm using 18hz @ 24db roll off. This setting still allow lower frequencies to the woofer but at a reduced level. At 24 db per octive the graph on the display still shows respone below 18hz I don' think i can exactly cut it off at 18.

I have to show respect for my woofers

stevem
03-10-2006, 09:58 PM
If i understand you correctly that is the current configuration that i'm using 18hz @ 24db roll off. This setting still allow lower frequencies to the woofer but at a reduced level. At 24 db per octive the graph on the display still shows respone below 18hz I don' think i can exactly cut it off at 18.

I have to show respect for my woofers

You should be OK with your current settings. You shouldn't need much better LF attenuation at normal playback levels. You'll still get low end response, but your woofers won't be moving excessively. Hope this helps.