L 300 Crossover Rebuilding-What Caps Would You Use?

[4313B]

Stick with voltages approved by JBL when using JBL transducers.

G.T. used 9V because it was convenient. JBL never delved into various voltages. G.T. said Ed Meitner also uses diodes which he thinks could be cool since one would then never have to change the battery.

- JBL used 18 volts in the S9500 & M9500.

G.T. said Japan asked for that after a special K2-S9800 was done that way for a certain famous reviewer.

If so I sense a lot of experimenting in the future

Well, have fun then!

Also I saw that JBL, on it's top speaker I believe, used charge coupled for part and didn't for another part. Is there a belief that it is audible in one range and not in another?

I don't know, we just do the whole network and worry about other things.



That's one limitation DIY folks don't have, they can worry about everything and try whatever they want.

[Ducatista47]

G.T. said Ed Meitner also uses diodes which he thinks could be cool since one would then never have to change the battery.

I would be most interested to know more about this.

Clark

[Earl K]

G.T. used 9V because it was convenient. JBL never delved into various voltages.

- I use 6 volts dc on the PLLXO before the amp and anywhere from 1.5 to 3 volts dc on the passives after the amp .
- Therefore, from a certain POV, in total, I'm using pretty standard operating voltages on my stuff ( though, apportioned differently ).

G.T. said Ed Meitner also uses diodes which he thinks could be cool since one would then never have to change the battery.

Hmmmm,

- I've thought some about a diode regulated current feed / though I haven't yet, concluded much of anything .
- Perhaps an inline combo, ( paralleled resistor/diode ) would offer the constant feed/dissipation ratios that I'm looking for .
( Something like ; Extremely High Value "R" with the diodes' voltage rating chosen to be less than half of the final DC potential ) .







psst; Oldmics, Solens' at 9 volts !

[Hoerninger]

G.T. said Ed Meitner also uses diodes which he thinks could be cool since one would then never have to change the battery.

Many years ago KOSS used a diode-capacitor network to provide the polarisation voltage for their electrostatic headphone. The voltage rsp. very low current were extracted from the audio signal (speaker out).

The situation for charge coupling is comparable as the current is extremly low. The circuit may be simpler as only a few volts are needed.

I hope this was helpful.
___________
Peter

[S20RVERT]

All this sounds great. I want to update my LX5's and was looking around the site for help. Now that I read about polystyrene and polypropylene I want this sort of upgrade. My Chicago JBL service center in says he gets his caps form JBL if they have them or finds the best avaliable. Can anyone help me with a Chicago service center that does these modern upgrades? If not Chicago, in the USA? Thanks

[Domino]

Well guys I was seriously considering charge coupling the crossovers in my L300's. About a year ago I changed out the capacitors in the crossovers. I installed Solens and have never been real happy with the harshness in the mids and highs. So I decided to try one more set of capacitors in the passive configuration first. This time I installed Audicaps by Audience. I have about 6 hours on them now and all I can say is WOW! What a difference. I have owned these speakers since new, purchased back in 1977, and they have never sounded so good. Sheer liquidity in the mids and highs. I can not recommend these more. When I asked them about break in they said that after about 6 hours they will start to attain their sound and be totally broken in after about 100 hours. They are right on target. They are not cheap by any means ($45.31 for a 16uf cap) but they are well worth it!

[toddalin]

Well guys I was seriously considering charge coupling the crossovers in my L300's. About a year ago I changed out the capacitors in the crossovers. I installed Solens and have never been real happy with the harshness in the mids and highs. So I decided to try one more set of capacitors in the passive configuration first. This time I installed Audicaps by Audience. I have about 6 hours on them now and all I can say is WOW! What a difference. I have owned these speakers since new, purchased back in 1977, and they have never sounded so good. Sheer liquidity in the mids and highs. I can not recommend these more. When I asked them about break in they said that after about 6 hours they will start to attain their sound and be totally broken in after about 100 hours. They are right on target. They are not cheap by any means ($45.31 for a 16uf cap) but they are well worth it!

I'm looking for some Solens. What values do you have?

[Earl K]

This time I installed Audicaps by Audience. I have about 6 hours on them now and all I can say is WOW!

Did you mean to write "Auricaps" ? Anyways, I'm glad you like them / they do consistently get good press .

FWIW & IME ;
(i) Placing two 6 uF caps back to back, ( with a net value of 3 uF ), results in a different sound than a single 3 uF cap ( from the same manufacturer ) .

(ii) Two caps back to back holding a DC charge ( but disconnected from the DC source ) will sound different than the same pair holding zero DC charge .

(iii) A Pair of caps holding a DC charge ( but not connected to the DC source ) will sound different after the DC source is connected .


(iv) The amount of DC voltage held within the cap pair represents another difference in sound .

(v) The big bad Solen signature sound of old / does disappear when they are wired up in series, & when those serial-pairs hold a DC charge .

<.

[4313B]

They are not cheap by any means ($45.31 for a 16uf cap) but they are well worth it!

Pick your poison...

[Domino]

My mistake. They are the Auricaps. I may still try charge coupling in the future but for now I'm gonna stick with these.
The Solen values that I have are (2) 16uf with a .47uf across each. (2) 1uf, and (4) 1.5 uf.

[4313B]

My mistake. They are the Auricaps. I may still try charge coupling in the future but for now I'm gonna stick with these.

It's probably best that you just stick with what you have after spending that kind of money on capacitors.



For those who want to stick with the non-biased topologies you might want to know that both Greg at JBL and Jeff at Sonicap suggested using the RelCaps with JBL compression drivers back when we were discussing such things.

Here's yet another page on capacitors for all of you folks out there with those terrible sounding JBL's running bypassed capacitors for the past 28 years:

http://www.10audio.com/sonicap_oimp_multicap.htm

Oops, it appears the RelCaps aren't all that after all. Oh well. :dont-know

I am sure engineers have a very good reason, and a couple of them have tried to educate me on this subject. I respect the science and electrical theory on this subject, and my technical background helps me to understand it fairly well. But there is one small problem: the bypasses all sound bad! They add a quality that at first sounds like an increase in air and detail, but after a couple of hours becomes an intrusive harshness and discontinuity in the upper treble. Remove the bypass: all of the detail is present but without that grating and annoying sound. The high frequencies are cleaner, smoother, and much more enjoyable. It doesn't matter if the bypass cap is Teflon®, polystyrene, or common polypropylene, the results are very similar. And to be avoided.

It's no wonder why JBL's are so maligned by the GP and I would definitely suggest that everyone remove all those bypass capacitors from their stock JBL networks. It is very easy to just snip the leads to the bypasses without having to rip everything apart. Those folks with JBL's older than ~ 1980 are "safe" because those networks didn't use bypass capacitors. That's probably why the older JBL's sound so much better than anything after ~ 1980. For those with Everest II's and any of the K2 Series, any decent speaker repair shop should be able to build you a nice pair of normal networks without the biased and bypassed capacitors so you can start to enjoy your systems.



Better yet, just go totally active and play with the much smaller and cheaper capacitance values in the active filters instead.

[Chas]

I'm looking for some Solens. What values do you have?

Todd, FYI:

http://www.solen.ca/v1/

[Ian Mackenzie]

As also noted in the article there are no blanket recommendations.

On bypassing I think it depends on when the capacitors were made and what they are. ie mylar.

The older metalised mylar lacked high frequency detail and bypassing helps restore that. It was better than nothing in other words. With the more modern caps you need to be a lot more careful.

That guy used too large a bypass cap. 0.1 is way to large with 8.00uf so I would take that aspect of the article with a grain of salt...he really had no idea. A value 0.01 would have worked better.

But I have encountered the cheese grater effect using metalised polypropolyne to make up the exact value with a Hovland.

It really was horrible.

My resident favourite no holds barred capacitor is the Mundorf Silver Oil.

In the same network I have the Sonicap Gen 1 shunted on the horn network. I am not happy I accepted that recommendation. The point being that while in direct A/B you may guess two capacitors are close what goes on inside them can cause a conflict when used in the same filter, either bypassed or in another location of the filter.

You should always use the same capacitor through the network if you can. Particularly the mid and high frequency filters.

The Mundorf Silver/Oil is Over Kill in most systems unless you need to compare just how bad other capacitors sound.

My suggestion is what you dont know won't hurt you. Don't A/B and you will believe what ever you put in there will be the Bee's knees.

Conclusion: Of the three capacitors evaluated in this application, the Mundorf silver/oil was objectively the best performer. It provided the best clarity, resolution, and transparency. However, if I was doing this project without the agenda of evaluating different capacitors, I would use the Sonicap Gen I because the small improvements I heard when substituting the Mondorfs were really only apparent on direct comparison. The Sonicaps offered the same level of musical enjoyment for far lower cost.

[Robh3606]

Why are you guys putting any stock in what's on the internet?? Who gives a damn what someone else thinks. Any Tom, Dick or Harry can put up a web page.

Build up a biased set for a small 2 way like the L20t's and use that to experiment with. When you find your favorite your done.

Those folks with JBL's older than ~ 1980 are "safe" because those networks didn't use bypass capacitors. That's probably why the older JBL's sound so much better than anything after ~ 1980. For those with Everest II's and any of the K2 Series, any decent speaker repair shop should be able to build you a nice pair of normal networks without the biased and bypassed capacitors so you can start to enjoy your systems.

LOL

Rob

[speakerdave]

Unfortunately some people are not going to get the ironical sarcasm.

David