Need help with weird crossover design on JBL KIT-speakers?

[Earl K]

While I enjoy some aspects of the "new" sound from the tweeters I also experience a very annoying sharpness during "S"-sounds in recordings, for example in vocals or in crash drums. When litsening to some recordings this is simply umbarable!Might this be due to the fact that these new caps let "too much" information pass into the tweeter? I mean, I haven't changed the XO-frequency, just upgraded the caps to better ones. Any suggestions on how to solve it?

Yes ( here's one ) !



- Those two caps are perfectly setup to "DC bias" .

- ( IME ) the presence of DC within a cap can help reduce ( and sometimes, even eliminate ) inexplicable sources of "newly-found" sibilance .

- An explanation of sorts ; a cap holding a charge of DC voltage becomes much less "self-resonant" when it's asked to pass AC signals.
- These " high-Q resonances" are heard when they get triggered by the appropriate ( frequency dependent ) signal .
- This ( statement, if accepted ) can help explain the ( not-so-often ) reported phenomena of an observed, "capacitor break-in period" .
- This also assumes that one will accept the statement that subjecting a cap to a significant AC load, will have the net effect of the capacitor acquiring a residual polarization ( ie; some DC offset where the cap never fully returns to "zero" / which is a "memory effect" of sorts / and you can blame gravity if you must "blame" something for this "asymmetrical" behavior in real world circuits ) .

- To implement; ( with the speaker un-plugged from the driving amplifier and the tweeter disconnected from those 2 caps ) add 1.5 volts dc ( obtained from a AA battery ) to the central junction of the 2.2 caps by applying the "+" voltage to the junction of the two caps ( the "-" side of the battery is connected to the minus side of the crossover network ) .
- Remove battery ( after 24 hours ) and allow the 2 caps to continue holding/storing the dc charge .
- Reconnect the speakers, as well as the network and get back to listening .

- If this seems like too much voodoo for you to accept / well, simply ignore this post ( keeping in mind that it also took quite a while to prove the world wasn't flat ) .

cheers

BTW; I (obviously) disagree with that part of Ruediger's assessment that there's nothing to be done .

[4343]

DC bias can be applied to the center junction of your two caps in series through a high value resistor, at least 1.5 Mohm, from a 9V battery the way JBL does.

[M1k@el]

4343

Earl K

That's something that I'll definitely look further into. If one can improve the sound just by applying a voltage over the caps that's a great solution!

Thanks

victoriobenatti

I feel like this is something I'll experiment with in the future since I study and don't really have the money (nor the time) to play around with different amps right now

Ruediger

Can You name an example recording?

Yes, every singe one of them! But just to give you some examples, Painkiller (Judas Priset), A momentary lapse of reason (Pink Floyd) and strangely every single record by Dire Straits! This leads me to believe that there is indeed something that can be done about those over-emphasised S-noises. Remember, I didn't experience the noises with the old caps

(Although I must agree with you that there are some recordings which are just BADLY mastered, I for one can not understand why so many people regard tracks by Katie Melua as audiophile-grade. According to me they are some of the most badly mastered tracks out there, blurry instruments which are barely audible coupled with moddy bass which makes me wonder if the recordings were done in a cave(?) But the most annoying thing is by far her over-reverbed voice which yield those S-sounds making every single track umbarable.)

But back to topic

I've done some research and concluded that the best thing to do right now is to build a new pair of N8000 networks. After all, they are very simple in their design and should therefore not be too expensice in parts.

http://www.jblproservice.com/pdf/Net...06 Network.pdf

The biggest advantage with building these will (I think) be that they attenuate the 2410 whist also taking care of the 077, I hope that this will make the crossover between them much smoother. With my current setup, the 2410 is not crossed over at all at high frequencies since it only operates off the LX13. This can't be good if there is a 077 connected as well, right?

[Mr. Widget]

...and strangely every single record by Dire Straits! This leads me to believe that there is indeed something that can be done about those over-emphasised S-noises. Remember, I didn't experience the noises with the old caps

It seems simple to me, you need a proper crossover.


Widget

[M1k@el]

It seems simple to me, you need a proper crossover.Widget

Yep, and they're on their way home to me now

[M1k@el]

Ok so thought I'll make an update on my progress

I've gone one better than my previous filters and have just finished my N8000 clones. Only problem is that the L-pad is only accessible by taking out the bass reflex tube. No big worry though since I've dialed the in 077's the way I like them by now.



The harsh and sharp sound is COMPLETELY gone now! The speakers sound much more coherent and I simply love the sound now.

[Mr. Widget]

Great news!

I hope you enjoy them for long time... or at least until the upgrade bug bites.


Widget

[M1k@el]

Great news!

I hope you enjoy them for long time... or at least until the upgrade bug bites.


Widget

I guess I get bit by the bug quite often to be honest

I do experience some distortion from the woofers when playing very deep bass, and to be honest I feel that the speakers are a little down on bass in general. Can this be due to demagnetization of the Alnico magnet? I just discovered that the woofers have actually been reconed by a previous owner, thus converted to the 2235(?):s.

AFAIK, there is a place in the US which specialises in remagnetizing speakers. Maybe I should contact them and send the woofers on a trip across the pond to breathe new life into them

[Mr. Widget]

I feel that the speakers are a little down on bass in general. Can this be due to demagnetization of the Alnico magnet? I just discovered that the woofers have actually been reconed by a previous owner, thus converted to the 2235(?):s.

I would confirm the cabinet size and tuning first... It is possible that mags need charging, but it is also possible the woofers don't have their mass rings or that you don't like 2235 woofers.


Widget

[M1k@el]

I would confirm the cabinet size and tuning first... It is possible that mags need charging, but it is also possible the woofers don't have their mass rings or that you don't like 2235 woofers.


Widget

How do I confirm whether they have mass rings or not? That's something I've never thought of.

I played a Hiphop track with very deep bass just to hear how the woofers responded, I must say I was a bit disappointed. The fast and dry bass become thin, farty and slow. In other words, all the opposite of what JBL-bass should be

.. and added to that came some distortion as well. It seems as though my woofers simply can't handle that type off deep bass.

EDIT:

Did some searching and found that the 2235H have the mass ring installed on top of the voicecoil and that it should weigh 35 grams, let's just hope that my reconed ones have them as well!