Capacitors...

[lpd]

Here's a link to the schematic for the 4333 crossover. I am thinking of replacing the caps. The horn is a 1.5 mf if I read the schematic right and the tweeter has a 1.5 and 1.0 mf cap...the bass driver a 20mf. What voltage should I get for the caps, and and brands you guys use?

[boputnam]

Hey, lpd...

You omitted the Link, but here's a few schematics for the 4333 series.

3133 and 3133A Network Schematics:

[Earl K]

Hi lpd
Your link wasn't posted but Bo fixed that. I think an answer to your question has been previously addressed in this ( or the last ) forum quite a few times . Here's a worthwhile quote on the subject

"If I were you I would just bypass your current stock JBL metallized mylars and NPE's with the 0.01 uF AudioCaps and give that a listen first."

Do a search within the whole forum structure for "Bypass Caps ". This will provide you with a basis of opinion that it's better to start your crossover renewel by bypassing the existing caps with .01 uf polypropylene types and then again "bypassing" the bypass cap with a .005 uf polystyrene type cap. This should "open up" the sonic qualities of your existing caps for cheap money.

Types to buy ? You can test-fly the "bypass" concept by purchasing caps from more mundane manufacturers. Try a local electronics shop for small quantities and for these values. You should still find that the concept offers great sonic improvements even from brands with little to no "Marque-value" .
If you've already done this "Bypassing"and aren't satified with the results then read the 4331 thread for a few " pricey " recommendations. Also do a search for " Dayton Caps ".

I'm personally quite happy with my "no name" main caps ( I actually don't know the type or manufacturer but they are smooth - & "slow" is not such a bad thing on a compression driver ). Because they're at least 20 years old they're likely Mylar types. ( Thats what I get for rummaging around in surplus parts bins). They resemble some of the caps found in 70's & 80s' Altec 1209 type crossovers. Mine are 75 VAC and I've never blown one apart - so I figure just about anything you buy these days ( usually over a 100 volts ) should be fine. I own a lot of Solen 400V "fast caps" but I find they aren't exactly complementary to JBL horn drivers.
I've never tried a "Charge-Coupled" topology to see if Solens sonic signature dissapears like I figure it might ( a worthwhile project to "eatup" my supply ).


regards ,> Earl K

[4313B]

Here's the L300 schematic as well.

"Solen 400V "fast caps" but I find they aren't exactly complementary to JBL horn drivers."

That's always been my experience as well.

"I've never tried a "Charge-Coupled" topology to see if Solens sonic signature dissapears like I figure it might ( a worthwhile project to "eatup" my supply )."

It helped but didn't sufficiently fix the issue in my opinion, but I would really like to hear what your experiences are.



I would just try bypassing the stock JBL mylars with 0.01uF poly and foil. Polypropylene tends to yield excellent transient character while polystyrene tends to yield three dimensionality. The older JBL statement systems such as the L250 and 250Ti used both 0.01 uF polypropylene and 0.005 uF polystyrene.

[scott fitlin]

My experience with caps for JBL and other vintage horn gear is a cap called Xicon! They used to be known as Transcap and they have a smooth sound! They arent expensive, but I have tried some VERY expensive caps that I always found to be TOO bright and forward sounding with JBL and Altec horns!

Xicon caps are available from www.partsexpress.com!

[4313B]

"I have tried some VERY expensive caps that I always found to be TOO bright and forward sounding with JBL and Altec horns!"

Yeah, it's a balancing act to be sure. The polystyrenes should take off some of that brightness and forwardness associated with metallized polypropylenes while adding depth and transparency.

G.T. has said on numerous occasions to use the best polypropylene capacitors one can buy and then just charge couple them. That is the most expensive solution.

I'm pretty much done with funding dielectric research myself

[Earl K]

Hi Giskard

Charge Coupling Solens - "It helped but didn't sufficiently fix the issue in my opinion, but I would really like to hear what your experiences are."

- Truthfully, that determination process is a now a ways off. I've got a lot of other investigations in the queue. I made my last sudy of caps - about 2 1/2 years ago. I find it pretty exhausting - if not downright fatiguing. I listen, at lower levels ( around 70 db ), to just the compression drivers in these studies. It's the only way I can get a solid impression of whats going on - Still that experience has left a lasting resistance to run the gamut again. I will get to it and I'll let you know my impressions if this forum hasn't sunk below the waves .

personal investment grade - polypropylenes ,,,,," That is the most expensive solution. I'm pretty much done with funding dielectric research myself"

Yep, I'm also afraid for my pocketbook in that regard. Though I think nothing of spending inordinant amounts of cash on different brands and models of compression drivers - all in the name of personal research. At least with diaphragms and drivers, I find the differences are pretty obvious and measurable. FWIW, I wouldn't have thought that I'd like a 2410/175 diaphragm in the 2426 motor ( & of course, this is an unsanctioned matchup and can't be warrantied ). This combo reminds me of an Altec 802-8D which has/had - I think - an underweight diaphragm when first introduced - hence the ease at which it was prone to " breaking or popping " the internal coil leads.
"Delicate sound from a delicate mechanism".

regards ,>Earl K

[Tom Loizeaux]

My response to these capacitor questions comes from a limited amount of experience with "tweaking" my 4343s' crossovers. I replaced a 4uf cap that had a broken lead with a similar type 3.9uf and paralled a .1uf Dayton with it. It was actually an original bypass cap that paralled a larger cap.
Then I added Dayton film/foil caps as bypass caps on all of the caps in the original crossover. I put .47 caps accross 72uf and 52uf caps, .22s accross the 20uf, .1 accross the 13.5uf, and .01s accross all the 1uf to 4 uf caps.
The idea is to "speed up" the transiants of the stock caps with significantly smaller value, high quality film/foil capacitors.
I never A/Bd differant makes of bypass caps but just went with the Daytons because I felt they would do the job.
If I wanted to replace original caps and not add bypass caps, I may have gone to AudioCap or some equivalent "high end" componant.
Again, without A/Bing the before/after sound, I find the completed crossovers to be very open, clear, and with plenty of attack and edge. The 4343s also exhibit a special smoothness that I find very satisfying.

Tom

[lpd]

I'm a little confused here. The 1.5mf caps on the schematic is that a .15mf or a 1.5mf because the size difference is huge. I'm thinking of going with solen caps.

Thanks.

[Earl K]

Hi lpd

(a) Circuit Cap Values

LF - the caps in that leg of the circuit are;
2 , 20uf caps
MF - the caps in that leg of the circuit are;
2, 16.5uf caps ( if you have the 3133a crossover - only one if you have the 3133 )
1, 1.5uf cap
HF - the caps in that leg of the circuit are;
1, 1.5uf cap
1, 1.0uf cap

(b) Replacement Priority(s)

If your going to replace caps. - I think the most audible effects are found in replacing those that are in series with the signal - especially that 16.5uf cap. in the horn circuit. - then the 1.5uf and 1.0uf in the tweeter circuit - then the 1.5uf in the horn circuit followed by the 2 parrallel caps in the woofer circuit.

regards <> Earl K

[Earl K]

Hi All

I've moved my post here ( where maybe it's more appropriate ) - away from the Cloning The 4435 Network thread . The original following quotes/thoughts from Giskard on charge-coupling are located at the above link.

by Giskard
"This past week I built a pair of charge coupled networks using Dayton metallized polypropylene capacitors for mains and no bypass capacitors. ,,,, These things got very clear."

Thats interesting - do you still use this crossover ?

by Giskard
"Overall the sound quality of the unbypassed, non-charge coupled metallized polypropylene's wasn't as good as the stock metallized mylar bypassed with polystyrene and polypropylene. (Duh! We've only known that for over twenty years now) Charge coupled, the metallized polypropylene's were slightly better than stock, with lower distortion, better top end, and exceptional attack, but not as much depth and warmth."

I'm experiencing something very similar right now. As some may remember my system is biamped. I've replaced the DC blocking caps on my compression drivers. The old caps were those unknown type, red-ended tubular types that you/Gisakrd once caught a glimpse of . The replacement caps are metallized polypropylene in oil ( AC motor-run, made by Mallory - more "dumpster-diving" - metaphorically ) . I haven't charge-coupled these yet ( I will this week ) but based on a comparison of their sonic signatures , my old caps must be a Mylar type. The comparitive difference is quite stark. The old caps actually seem to offer a type of spectral compression/limiting in the midband area that keeps my compression drivers from jumping into my face. This apparent "torque" decrease does help the compression driver work in closer concert with the paper coned tranducers. It now seems my whole kludged together MTM setup has been "balanced" around the speed signature of these old caps. FWIW, the new caps are certainly closer sounding to " a straight -wire ". Too bad that, because in fact I'm looking for some actual filtering/slowing-action to help in the blending/voicing of the disparate component types.

I also bought "paper & oil" AC motor-run caps. Interesting, but they didn't have quite enough of the "soft-compression" signature I was looking for. In fact , they are a lot more "straight wire" than I expected. They are quite charming on trombones and tenor saxes/voices but certainly not as "clear & accurate or fast" as the Mallorys'. Lets say they are like filtering the polyproylenes through an MP3 algorithm. Bypassing them with a mix of Solens and other mystery-bin poly-types created something truly horrid . Well, actually, if one is an electric quitar player, it's a dielectric combo that might be useful for creative expression.

by Giskard
"I would say warmth is what was lacking most though."

- Did you ever recover that lost warmth ?

My system has lost apparent warmth and the front to back imaging has also taken quite a hit - I guess I should expect this when a compression driver is allowed to "straight-arm" the listener - like a rambling fullback in mid-stride. I've had to resort to using a 2123h instead of my usual le10 mid/bass to recover/invent/ some warmth. And I do love the neutrality of the le10 as a midbass driver but so far it just won't "shake-hands" with any polypropylene cap/compression driver combo . I like these Mallory caps and hear great promise in them which is why I haven't just turfed them and gone back to my mystery cap setup. Among the things that I like; - the apparent "Q" of my 45° horns changed when the polypropylene caps where intalled ( this also happened with the paper/oil type ) . Horn "Q" went down - and apparent midband dispersion went up.

by Giskard
" Needless to say, I will be installing some good film and foil bypass caps this week. Hopefully the Daytons won't respond negatively like Solen's do when bypassed."

- Did you do ever do this and how did the Daytons respond to the bypassing?


- I'm going to try blending dielectric types in a charge-coupled topology this coming week. ( One dielectric type on side"A" - the other type on side "B" ).

- Last week I found I could submerge the sonic signature of the polypropylene cap if I "swamped it" with huge values of the "Mylar" type. A 6 to 1 mix ratio made the polypropylenes' signature dissappear . This is what has led me to try blending different types - even with the predicted "timing" errors - though the class A charge-coupling ought to remedy that drawback. Has anyone ever tried this ?

regards <> Earl K

[Ian Mackenzie]

Earl,

Very interesting comments about you cap blending experiements.

I had a similar experience when I tried my mockup 3145 network with the 2308/8 and slot.

For days I had sleepless nights at the rasping sound from the horns. I could just hear Jon saying..told ya so those 2307's........Seas shell sound...well this was way worse.

Well, one night I did some critical listeniing and the sound from the 2307 sounded clipped and rough as rags. (I checked the network over and over for shorts and faults but nup , no mistakes)

What I had was in the horn high pass was Holvands in parelleled with a metallized polypropylene (mid price rang part) to get the right values, thinking the Holvands would make the lesser expensive caps sound great.

As a last resort I pulled it all apart and parrelleled the a pair of Holvands to get 8uf and then used a Axon Musiccap (metalised polypropylene )12 uf for the other series capacitor.

The difference was chalk and cheese, clean, smooth and uncoloured sound. I am saving up for Hovlands all round and I suspect the 2307/08 has had its reputaiton some what spoiled by mid fi caps in the past.

Ian

[4313B]

The stock JBL MM bypassed with MPP isn't a bad combination and the price is great. In the L250 and 250Ti G.T. added the MPS bypass caps as well and I've used this configuration of MM bypassed with MPP and MPS in every JBL system I've built since. Very economical and highly effective.

Over the years we've tried other combinations and I have to say (G.T. concurs) that the very popular Solen's are WAY too hot for JBL transducers. Electro-Cap was the MM capacitor of choice for many years but they were bought by RTI Electronics back in the mid to late 90's and I've yet to see them come back in the U.S. market.

On the question of the Dayton capacitors - I find the MPP less obnoxious than the Solen capacitors but even so...

I did bypass the Dayton MPP with Dayton PP&F and the result wasn't very nice. I replaced the Dayton PP&F with the AudioCap PP&F and the difference was astounding. The AudioCap is simply fantastic. I'm still waiting for my AudioCap PS&F to show up but for now the Dayton MPP bypassed with AudioCap PP&F is pretty impressive. I would prefer to use a top quality MM instead of the MPP but I haven't been able to find another source since the demise of Electro-Cap.

I have to agree with G.T. that the best course would be all biased PP&F but that is one very expensive proposition, especially in the larger systems that use large value capacitors. Incidentally, G.T. does not feel that the series capacitors are more critical than the parallel capacitors, he finds both equally affecting.

MM = metallized mylar
MPP = metallized polypropylene
MPS = metallized polystyrene
PP&F = polypropylene and foil
PS&F = polystyrene and foil

[GordonW]

Giskard (or any of you other folks, naturally), you ever auditioned the GE 40L, 41L and 42L -series poly caps that Madisound sells, for bypass, etc? I've used those things, and so far, so good, I think...

Regards,
Gordon.

[Earl K]

Hi Gordon

No, I haven't tried those GE caps.
Since I'm in Toronto, I'm forced to buy local (Cdn) solutions .
Shipping - border/brokerage costs force this direction - so much for NAFTA .

Does "GE" mean General Electric ?

My paper in oil "Motor Run" caps are General Electric .

regards <. Earl K