Oh I see. I wasn't sure if the cap was strictly for the protection of the tweeter or if it did serve some acoustic purpose.
The most important thing though is how I should go about protecting these tweeters from future damage if I purchase JBL replacements. I wouldn't want to sink a $60 investment if something happens to my amplifier that stresses out these speakers. Is there something that I could install to prevent power spikes from damaging these fragile tweeters?
And by the way, the set of 410's that I was using previously had the same problem. I guess that I couldn't tell that the tweeters were having issues since the 4" drivers in that model were able to compensate.
Thanks again.
*bump*
Does anyone know of a way to protect these tweeters from damage if I purchase the delicate stock ones?
Otherwise, I'm probably just going to hack up the plastic horn pieces to enable them to fit competent, high-quality tweeters.
Thanks
Does anyone know of a way to protect these tweeters from damage if I purchase the delicate stock ones?
Otherwise, I'm probably just going to hack up the plastic horn pieces to enable them to fit competent, high-quality tweeters.
Thanks
Dabbler, thanks for the recommendation. I will make sure to install an appropriate polyswitch when I get around to it.
I got my amplifier back to working condition last night (I had to find a way to run shielded cables from the balanced input on the amplifier to the unbalanced output of a laptop). Anyway, I had a chance to audition the 810's again and it actually seems like the tweeters are working decently. In comparison with my SP-BL41LR's, the tweeters on the 810's don't seem to be able to reach down low enough to match the woofers in these speakers and or the woofers cannot reach high enough to hand-off to the tweeters.
I checked the crossovers and there is a polypropylene capacitor in series with the tweeters, so I am not worried about that being a problem anymore.
The woofers on the 810's on the other hand are rather poor. From about 100hz to 600hz, the 8" woofers work efficiently, however anything between about 1000hz and 2600hz (where the tweeters come in) is just not represented well. I would say that there is a 1600hz gap in which the speakers are not representing my audio faithfully and where overall volume diminishes. Even at 2600hz, the tweeters are beginning to break up a bit (I do not believe that they should be crossed at 2600hz for an optimally-flat frequency response). I have had multiple people confirm this problem.
Therefore, I propose the following: Since the same exact tweeter is crossed over at 3000hz in the JBL 410's, I would raise the crossover to 3000hz and replace the woofers with more competent (better) woofers that are able to maintain a flat frequency response up to around 2600-3000hz. I don't mind sacrificing a bit of low-end since I have a Paradigm SB-90 subwoofer that will cover anything between about 30hz and 90hz well. Thus, I might look for a woofer that will respond well from between about 120hz and 3000hz if possible.
This SHOULD fix my problem. What do you guys think? Do you have any woofers that you would recommend and could I just raise the crossover frequency by changing out the poly capacitors that are in-line with the tweeters? Finally, since these woofers are not part of horns, am I correct when I say that I shouldn't have to worry as much about their interaction with the horn component?
I could leave the crossover point at 2600hz if you believe that the larger plastic horns in the 810's vs the 410's are somehow optimizing these tweeters for a lower crossover frequency, however I don't see how raising the crossover into the tweeters' "sweet spots" should harm anything.
Here is a rough frequency response graph that illustrates what I am talking about:
Edit: After some searching on Partsexpress, it's VERY hard to find a decent 8" woofer with a relatively flat frequency response up to 2600hz, let alone 3000hz! Since the stock woofer is so inexpensive, I can only imagine that this gap I am hearing is quite substantial!
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tweeter protector lamp - I've seen these used in a few speakers over the years but you need to know how much power the specific tweeter uses to pick the right protector lamp.......
I'm struggling to follow this, but it seems JBL have fitted an 8" 4.4 ohm polypropylene woofer to a horn-loaded puny 5.5 ohm mylar tweeter. I get a crossover around 5000Hz on the 5.5ohm tweeter.
That shunt 0.33mH/30uF trap is an odd thing to fit. It seems to boost output around 1600Hz. If it was like a bextrene KEF B200 bass, you'd probably fit a simple shunt 7uF capacitor across the bass filter and do without the trap and the 33uF.
What is odd, is that you really shouldn't be expecting an 8" bass to cover up to 5000Hz. That and the plastic horn must sound horrible! 😉
That shunt 0.33mH/30uF trap is an odd thing to fit. It seems to boost output around 1600Hz. If it was like a bextrene KEF B200 bass, you'd probably fit a simple shunt 7uF capacitor across the bass filter and do without the trap and the 33uF.
What is odd, is that you really shouldn't be expecting an 8" bass to cover up to 5000Hz. That and the plastic horn must sound horrible! 😉
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Its a poor design, not really worth tinkering with. One option would be to remove the horn altogether and fit a waveguide and compression driver using mini-econowave crossover. But it lookls like the horn is glued on.
System7, thanks for the helpful post!
And yes, it does appear that JBL hoped that all of the horribleness in these speakers would blend itself into an acceptable mediocrity when combined with a large enough subwoofer lol.
I didn't buy these speakers to serve as part of my primary sound system so I was never aiming for excellent sound however. In fact, I was originally hoping to get some advice as to what I should look at for replacement tweeters to make these speakers sound acceptable. I don't care if I have to ball-park the adjustments because I'm pretty sure that almost anything will improve sound quality lol.
I could replace the horn and tweeter with a waveguide and compression driver first before fiddling with the woofer. What cost-effective driver and horn would you recommend using? Of course, I will measure the hole to find the exact size of horn required. Also, what crossover frequency should I be aiming for when I build a crossover?
By the way, this cheap plastic horn might be glued on, but it WILL come off one way or another. 😉
Finally, the cabinets are actually quite nice (they come with quality speaker cable posts too) and I think that the speakers look quite acceptable from the outside. Just because of this, I think that they are worth fiddling with.
Edit: I found a really inexpensive horn driver that is getting great reviews on Partsexpress:
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=270-069
A guy called speaker-guy posted this recommendation for a crossover:
Build a second order Linkwitz-Riley 2000 HZ crossover for these drivers and hear them come alive!
Step 1: Use 2 - (20 watt, 20 ohm) resistors part number 017-20. Twist them together in parallel getting a 40-watt at 10-ohm load. Solder them across the Driver terminals.
Step 2: Also place a 1.5 mH Coil - Part Number 255-426 across the Driver terminals with the resistors.
Step 3: Because we are creating a second order crossover which inverts the phase 180 degrees, place a 4 uF capacitor (part number 027-421) in-line from the source (+) lead to the (-) terminal on your horn driver. Connect the ground (-) wire to the hot (+) lead of the horn driver
This allows you to couple this horn driver with a speaker / woofer without using a crossover to stop the woofer from going as far up in frequency as it can. The phase is linear complimenting the full spectrum without peaks.
What do you think about combining this with the stock 8 inch woofer?
And yes, it does appear that JBL hoped that all of the horribleness in these speakers would blend itself into an acceptable mediocrity when combined with a large enough subwoofer lol.
I didn't buy these speakers to serve as part of my primary sound system so I was never aiming for excellent sound however. In fact, I was originally hoping to get some advice as to what I should look at for replacement tweeters to make these speakers sound acceptable. I don't care if I have to ball-park the adjustments because I'm pretty sure that almost anything will improve sound quality lol.
I could replace the horn and tweeter with a waveguide and compression driver first before fiddling with the woofer. What cost-effective driver and horn would you recommend using? Of course, I will measure the hole to find the exact size of horn required. Also, what crossover frequency should I be aiming for when I build a crossover?
By the way, this cheap plastic horn might be glued on, but it WILL come off one way or another. 😉
Finally, the cabinets are actually quite nice (they come with quality speaker cable posts too) and I think that the speakers look quite acceptable from the outside. Just because of this, I think that they are worth fiddling with.
Edit: I found a really inexpensive horn driver that is getting great reviews on Partsexpress:
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=270-069
A guy called speaker-guy posted this recommendation for a crossover:
Build a second order Linkwitz-Riley 2000 HZ crossover for these drivers and hear them come alive!
Step 1: Use 2 - (20 watt, 20 ohm) resistors part number 017-20. Twist them together in parallel getting a 40-watt at 10-ohm load. Solder them across the Driver terminals.
Step 2: Also place a 1.5 mH Coil - Part Number 255-426 across the Driver terminals with the resistors.
Step 3: Because we are creating a second order crossover which inverts the phase 180 degrees, place a 4 uF capacitor (part number 027-421) in-line from the source (+) lead to the (-) terminal on your horn driver. Connect the ground (-) wire to the hot (+) lead of the horn driver
This allows you to couple this horn driver with a speaker / woofer without using a crossover to stop the woofer from going as far up in frequency as it can. The phase is linear complimenting the full spectrum without peaks.
What do you think about combining this with the stock 8 inch woofer?
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I'd dump the horn idea altogether. Especially for a speaker with a mere 89dB sensitivity. Just my opinion though.
In essence you need to measure the hole in the baffle and figure what better tweeter you can fit. Maybe a 104 or 110mm jobbie would do it. Don't know. But most tweeters get near 90dB.
You could do worse than fit a waveguide Monacor DT-300 IMO. Pad it a bit to get the efficiency down though.
Vifa C17WH-
The polypropylene bass ought to be OK with a lowish crossover.
In essence you need to measure the hole in the baffle and figure what better tweeter you can fit. Maybe a 104 or 110mm jobbie would do it. Don't know. But most tweeters get near 90dB.
You could do worse than fit a waveguide Monacor DT-300 IMO. Pad it a bit to get the efficiency down though.
Vifa C17WH-
The polypropylene bass ought to be OK with a lowish crossover.
Oh cool. I'll see if I can get that Monacor to fit in the baffle. I'll be out of town next week, however I'll have the Monacors (or something similar) in by the time I get back so I will keep you updated on my progress.
Should I build a basic 12db L-R crossover at 2000hz to interface with the 8" woofer?
Also, if I ever upgrade the bass woofer, should I look for something that does not need a boost at 1600hz and that blends with the Monacor at 2000hz?
Thanks again
I think it's doable with the Monacor DT-300! 🙂
Monacor DT-300
2kHz crossover. I'd regard the waveguide as optional. It will make for midrange shout that might be annoying and you probably don't need the level. The bass should be OK and smooth enough rolling off around 2kHz too, if it's like most polypropylenes. This IS diyaudio, so who knows how it will work out, but a 2kHz 2nd order Linkwitz-riley filter with an oversized bass coil should be about right.
But to me, a broken speaker is just a box ready to put some good drivers in. 😀
Monacor DT-300
2kHz crossover. I'd regard the waveguide as optional. It will make for midrange shout that might be annoying and you probably don't need the level. The bass should be OK and smooth enough rolling off around 2kHz too, if it's like most polypropylenes. This IS diyaudio, so who knows how it will work out, but a 2kHz 2nd order Linkwitz-riley filter with an oversized bass coil should be about right.
But to me, a broken speaker is just a box ready to put some good drivers in. 😀
If you can remove that horn without breaking the box then you have a few options to work with. In that diagram it appears it might be fixed by screws from the inside?
System7, you are the man! It's great when people gets excited about diy work.
Dabbler, I'll make sure to check and see if the horn is held in place by screws when I measure the baffle tomorrow. If not, it's only plastic so I bet that I could break it apart without damaging the box (the boxes are made in the US). If the Monacor doesn't fit or doesn't work out for some reason, what other options do you know of?
Thanks again.
Dabbler, I'll make sure to check and see if the horn is held in place by screws when I measure the baffle tomorrow. If not, it's only plastic so I bet that I could break it apart without damaging the box (the boxes are made in the US). If the Monacor doesn't fit or doesn't work out for some reason, what other options do you know of?
Thanks again.
Oh, too kind! 😱
The monacor will work out, for sure. You will find an oval hole behind the plastic horn, which looks like it is just held by 4 plastic pins glued to the baffle. Can't quite see how big the hole is, but the DT-300 is basically a huge 116mm diameter so will probably cover the gap on its own. With the waveguide you are bound to be able to cover it.
Matching levels is just a question of adding resistances to the highpass filter. Several different ways to do that based on the Re of the tweeter.
Keep reading Troels on the 1st order tweeter FILTER he later favours with the DT-300. He has conveniently already calculated the LCR Fs tweeter correction for you:
Vifa C17-
And a bit of strengthening of the plastic waveguide:
C17mk4
A hobby is, after all, an INTERESTING waste of time. 🙂
The monacor will work out, for sure. You will find an oval hole behind the plastic horn, which looks like it is just held by 4 plastic pins glued to the baffle. Can't quite see how big the hole is, but the DT-300 is basically a huge 116mm diameter so will probably cover the gap on its own. With the waveguide you are bound to be able to cover it.
Matching levels is just a question of adding resistances to the highpass filter. Several different ways to do that based on the Re of the tweeter.
Keep reading Troels on the 1st order tweeter FILTER he later favours with the DT-300. He has conveniently already calculated the LCR Fs tweeter correction for you:
Vifa C17-
And a bit of strengthening of the plastic waveguide:
C17mk4
A hobby is, after all, an INTERESTING waste of time. 🙂
Hey system7,
I have both good and bad news... I was able to remove the plastic horn and tweeter from one of the cabinets REALLY easily! It was simply attached with some thick tape. Also, the cabinets look plenty thick and well-built.
The bad news is that I'm left with another roughly-square hole where the horn was. The space measures approximately 164mm side to side and 224 mm diagonally... I could probably fit a 6.5 inch woofer in there with room to spare. The Monacor with wave guide is only 169 mm side to side, so I do not know if I will be able to screw it in without cracking the MDF cabinet.
I'm left with a couple options I guess. I could purchase some MDF cut to size and glue it to the existing cabinet as a mount for the Monacor DT300. I could also look at purchasing a regular horn-mounted tweeter that would fill up the entire gap. Also, if there is such a thing as a tweeter with a larger waveguide, I could mount that in the existing hole. While I'm in there, I could also separate the woofer's compartment from the tweeter's compartment (if you think that matters).
What do you think?
Finally, I used an online calculator to generate a "proper" Linkwitz-Riley 2000hz crossover for an 8 ohm tweeter and a 4.4 ohm woofer. I received the following values: 4.98uf for C1, 1.27mH for L1 / 9.05uf for C2, .7mH for L2 (C1/L1= high pass, C2/L2= low pass). Do these look correct?
http://www.diyaudioandvideo.com/Calculator/XOver/
As for the first order filter, would this create a nice roll-off at the high end for the tweeter?
I was thinking about padding the tweeters a bit to reduce efficiency, but should I add resistance to the high pass filter at the same time?
Sorry about all of the questions. The nuances of speaker design are fascinating!
I have both good and bad news... I was able to remove the plastic horn and tweeter from one of the cabinets REALLY easily! It was simply attached with some thick tape. Also, the cabinets look plenty thick and well-built.
The bad news is that I'm left with another roughly-square hole where the horn was. The space measures approximately 164mm side to side and 224 mm diagonally... I could probably fit a 6.5 inch woofer in there with room to spare. The Monacor with wave guide is only 169 mm side to side, so I do not know if I will be able to screw it in without cracking the MDF cabinet.
I'm left with a couple options I guess. I could purchase some MDF cut to size and glue it to the existing cabinet as a mount for the Monacor DT300. I could also look at purchasing a regular horn-mounted tweeter that would fill up the entire gap. Also, if there is such a thing as a tweeter with a larger waveguide, I could mount that in the existing hole. While I'm in there, I could also separate the woofer's compartment from the tweeter's compartment (if you think that matters).
What do you think?
Finally, I used an online calculator to generate a "proper" Linkwitz-Riley 2000hz crossover for an 8 ohm tweeter and a 4.4 ohm woofer. I received the following values: 4.98uf for C1, 1.27mH for L1 / 9.05uf for C2, .7mH for L2 (C1/L1= high pass, C2/L2= low pass). Do these look correct?
http://www.diyaudioandvideo.com/Calculator/XOver/
As for the first order filter, would this create a nice roll-off at the high end for the tweeter?
I was thinking about padding the tweeters a bit to reduce efficiency, but should I add resistance to the high pass filter at the same time?
Sorry about all of the questions. The nuances of speaker design are fascinating!
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That space is begging for a horn, especially if you want to use these for home theatre.
It looks like the RCF H100 would fit perfectly.
Or if you're on a budget: Pyle Pro PH715 1" Bolt-On Constant Directivity Horn 292-2576
Connect a good cheap compression driver and youre good to go, with potential to upgrade to a higher efficiency woofer in the future.
It looks like the RCF H100 would fit perfectly.
Or if you're on a budget: Pyle Pro PH715 1" Bolt-On Constant Directivity Horn 292-2576
Connect a good cheap compression driver and youre good to go, with potential to upgrade to a higher efficiency woofer in the future.
Impedence is not fixed, it varies. These calculators are based on a theoretical flat frequency response and impedence so you wont get a "proper" LR crossover.
Your best bet if you are keen to play around this stuff is to grab a bag of cheap components, try a few crossovers based on these calculators then measure and re-adjust until you get close to what you want. You may not get a great result but you will learn something.
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Hey, thanks a bunch guys! I finally got everything I needed to upgrade my speakers and made the modifications to one of the two. I then set it up next to the other in my living room and the difference is incredible! Gone is the sense that the mid-range is lacking. Now, there is a real presence to my music!
I had to use 25 ohms of resistors just to get the horn compression driver to match the inefficient woofer though. I feel that the entire setup would work much better with a more efficient woofer. I'll have to keep my eyes open for one. Also, highs seem to be lacking a bit on the PDS442. I wonder what would be causing that?
I chickened out and purchased a Dayton Audio 2000hz crossover with a 4ohm option for the woofer. It seems to be working fairly well with this driver combo tho. I am positive I could have gotten better performance with a custom crossover but I just didn't have the time, patience, or money to build one and then try out different combinations of inductors and capacitors.
I am using a PDS 442 Pyle Pro compression driver and a Pyle Pro PH810 horn. The PH810 horn actually dropped in really easily with a bit of shaving to the housing opening. Anyway for the extra $130, I'd say this was definitely a worthwhile upgrade.
I had to use 25 ohms of resistors just to get the horn compression driver to match the inefficient woofer though. I feel that the entire setup would work much better with a more efficient woofer. I'll have to keep my eyes open for one. Also, highs seem to be lacking a bit on the PDS442. I wonder what would be causing that?
I chickened out and purchased a Dayton Audio 2000hz crossover with a 4ohm option for the woofer. It seems to be working fairly well with this driver combo tho. I am positive I could have gotten better performance with a custom crossover but I just didn't have the time, patience, or money to build one and then try out different combinations of inductors and capacitors.
I am using a PDS 442 Pyle Pro compression driver and a Pyle Pro PH810 horn. The PH810 horn actually dropped in really easily with a bit of shaving to the housing opening. Anyway for the extra $130, I'd say this was definitely a worthwhile upgrade.
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Here's another update:
I spoke with a tech support employee at Parts Express and he noted that some of the problems that I am experiencing with my audio at around 2500 hz might be related to a bump in response present in many 2 way speakers crossed with a 2nd order crossover. He recommended that I build a zobel network for the woofer with a 33uf capacitor and an 8 ohm resistor and that I add an l-pad to the tweeter in order to bring it in line with the sensitivity of the woofer. I just ordered those things and will keep you guys updated on my progress next weekend.
I spoke with a tech support employee at Parts Express and he noted that some of the problems that I am experiencing with my audio at around 2500 hz might be related to a bump in response present in many 2 way speakers crossed with a 2nd order crossover. He recommended that I build a zobel network for the woofer with a 33uf capacitor and an 8 ohm resistor and that I add an l-pad to the tweeter in order to bring it in line with the sensitivity of the woofer. I just ordered those things and will keep you guys updated on my progress next weekend.
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