JBL K2 S5500 Crossver Upgrade?

[kelossus]

Never thought I'd own a pair of these without importing from Japan but low and behold a pair showed within a 3 hour drive. Didn't get them for cheap but sometimes you'll pay the $$$ if you want something.

Got these home but accidentally snapped a binding post in the back of my ute and the battery had completely disintegrated, the original battery holder was toast. A set of binding posts later and new battery holders these things are up and running and sound great! I couldn't help but notice the crossover components could do with an upgrade. At this point I am considering a complete re-cap with Jantzen cross-caps and Elko electros for the bigger values, also replacing the ceramic resistors with MOX types. While I'm there I think I will change the resistor values in the attenuation network as I would like to pad the horn down a bit further. My room isn't massive at 13.5 ft by 23ft so a little less horn, or at least the option would be great.

I would like to replace the iron core inductors in the compression driver network but the original network is quite small so I don't think I'll be able to. I will at least replace the iron core in the woofer network as it's on a separate board with plenty of real estate.

The Australian Distributor for Jantzen is going to perform the work and he said if it were him he would build whole new networks without charge coupling. Myself being a GT fan wants to keep them as he designed, so I will.

The crossovers seem to built to a budget so I think some new caps and resistors should prove worthwhile.

Very little info on these early K2's online and pretty much no listening impressions on this site. Most of the reading I have done came from French forums oddly enough.

Any advice and thoughts on this potential upgrade would be great.

[Robh3606]

Nice speakers!

Be really careful handing off a system like that for anyone to make changes or to "upgrade".

First off don't go swapping out the inductors unless you know the DCR values and can look at it in a simulator to see if there are any significant changes with the new parts. Some of those inductors could have significant DCR values by design and if changed you will re-voice the speaker.

If you really want new networks leave the stock networks alone. Build new ones and have the originals safe and sound.

If it were me looking to purchase a system like that I wouldn't touch it with a 10 ft pole once I found out the original networks had been "upgraded"

Rob

[kelossus]

Nice speakers!

Be really careful handing off a system like that for anyone to make changes or to "upgrade".

First off don't go swapping out the inductors unless you know the DCR values and can look at it in a simulator to see if there are any significant changes with the new parts. Some of those inductors could have significant DCR values by design and if changed you will re-voice the speaker.
If you really want new networks leave the stock networks alone. Build new ones and have the originals safe and sound.

If it were me looking to purchase a system like that I wouldn't touch it with a 10 ft pole once I found out the original networks had been "upgraded"

Rob

I know what you mean. Aware of DCR matching in regards to the inductors and series resistors are added to make up whatever difference there may be. As with changing electro's, ESR is noted.

I really don't think JBL selected the capacitors based on anything other than cost saving. They are budget bennic style film caps and the larger values electrolytics are ALCAPS found in every budget speaker of the time. Nothing high end here. Just working to a budget keeping the bean counters happy. Giskard recreated numerous JBL networks and never mentioned the importance of keeping the original capacitors, from reading his posts he used anything from Solens to Jantzens. As long as you match the values closely I think using a higher quality capacitors isn't going to harm a thing.

Would be willing to bet GT didn't voice the network based on the capacitors selected and I doubt he would recommend building the network with cheap caps if you were willing to spend more. I might be completely crazy for such assumptions but JBL have never really used quality parts in the networks.

Apologies if I come off argumentative and I understand the desire to keep them original. The thing is these were built to a budget, clearly seen in the lightweight brass binding posts and crossover components. Drivers and cabinets are top quality.

[Robh3606]

Giskard recreated numerous JBL networks and never mentioned the importance of keeping the original capacitors, from reading his posts he used anything from Solens to Jantzens. As long as you match the values closely I think using a higher quality capacitors isn't going to harm a thing.

I don't see your post as argumentative just wanted to make sure you had your eyes open so to speak. Everything is done on a budget so I understand where you are coming from.

What matters in the end is that the voltage drive of the "upgraded network" is the same as the original. Giskard/4313B was able to come up with equivalent networks for several systems by using this method.

Rob

[Earl K]

Here's a nice ( Japanese ) blog showing all the guts of the S5500 .

( I have Google translate set-up for automatic translation services & the text in this blog translates pretty well > for Japanese ) .



I too would be replacing caps and ( at least ) some coils if I owned those beauties ( FWIW ) .

I'd be inclined to simply have that Jantzen rep build all new ( non CCed ) external networks using his recommended parts ( since I have no clue what DC-biased Jantzens sound like ).

If the Jantzens don't work out ( IOW; maybe they change the voicing too much for your liking ) then I would then install the recommended Solen's within the HF ( horn ) circuit ( using the original networks ) and then give those an audition .

I use ( very lightly ) DC-Biased Solens ( less than a volt ) and know what they do in a horn circuit ( Uber clarity ) on my Altec 288-8K drivers.

[kelossus]

I too would be replacing caps and ( at least ) some coils if I owned those beauties ( FWIW ) .

I'd be inclined to simply have that Jantzen rep build all new ( non CCed ) external networks using his recommended parts ( since I have no clue what DC-biased Jantzens sound like ).

Thanks for the link, I hadn't seen that write up.

Interesting thought, I would never have considered ditching the CC'd networks but the reduction in capacitor values would allow for more premium parts. While also leaving the original networks completely untouched. I do remember a post where Giskard mentioned building a CC'd network with the Jantzen crosscaps and it worked out well.

So here is the predicament, is charge coupling with cheaper capacitors better then building a standard network with premium parts?

[Mr. Widget]

So here is the predicament, is charge coupling with cheaper capacitors better then building a standard network with premium parts?

Let us know what you think once you've given it a go.

I agree with Rob. If you want to play with these vintage speakers, build complete replacement networks... CC'd or not, and then AB the factory network with your "upgraded" network.


Widget

[kelossus]

Let us know what you think once you've given it a go.

I agree with Rob. If you want to play with these vintage speakers, build complete replacement networks... CC'd or not, and then AB the factory network with your "upgraded" network.


Widget

If you had to hinge a bet would you say the rebuilt network remaining CC'd, using high quality parts would be superior to the original? This is assuming the DCR and ESR of all the components are matched to the original network.

[Robh3606]

If you had to hinge a bet would you say the rebuilt network remaining CC'd, using high quality parts would be superior to the original? This is assuming the DCR and ESR of all the components are matched to the original network.

You have a really big advantage of having the original networks. You can measure the ESR/DCR's if you want.

You can also have your builder measure the voltage drive of the stock networks into a dummy load and compare the new networks too that.

If they match you should be good to go and any differences will be about the differences between the networks and not because the voltage drives don't match.

Rob

[kelossus]

If the original parts can't be improved upon maybe it's not worth changing anything.

[Mr. Widget]

If the original parts can't be improved upon maybe it's not worth changing anything.

If they were my speakers and they pleased me, I spend my time listening to them and leave them stock.


Widget