L-112 as oppossed to L-110

[4313B]

The N110A can be modified to use the 066 or the 044 with excellent results. Both are quite a bit better than the cheaper 033 with the 066 having "better" overall frequency response that extends higher while the 044 has lower power compression and greater power handling. Plus, the 044 doesn't have the "18 kHz" anomaly numerous 066's "suffered" from.

The N212 network shows the minute change in the HF conjugate to use the 066. To use the 044 one has to change C5 to 14.0uF.

As an aside, the L110A was the first JBL loudspeaker to employ bypass capacitors.

[boputnam]

... them networks. I was just looking at them (found the original posting), but it is VERY handy side-by-side with your detailed explanation.

I'm guessing that 18kHz anomaly for the 066's is what makes my Goldens cringe on occasion? (anomaly = spike)

[4313B]

"I'm guessing that 18kHz anomaly for the 066's is what makes my Goldens cringe on occasion? (anomaly = spike) "

Perhaps... You're talking about the 066 in the 4313? A bit too bright? The L166, L212 and 4313 require excellent amplification. The 066 definitely has issues with some amplifiers, it can seem quite strident. The 033 and 044 don't seem to be quite as picky, I don't know why. These are just my observations.

You probably don't have the capacitors in the 4313's bypassed either right? I recently listened to a pair of unbypassed L212's and was actually shocked at how lousy they sounded. Installing bypass caps fixed the situation. It's been quite awhile since I listened to unbypassed JBL's, I'd all but forgotten how lousy they sound.

[boputnam]

The L166, L212 and 4313 require excellent amplification

True, I find.

At the risk of (here I go again...) instigating a severe digression onto amplification preferences, I just migrated from a sizeable Onkyo M-504 165-watt per amp to my QSC CX302's (200 watts per), and the improvement was palpable. The Onkyo clearly lacked low-end, and the high-end was simply not as brilliant (although the specs sure did not reveal it). Nothing else in the rig was altered. The improvement in reproduction and imaging is simply stunner. Icy clear.

And no, the caps in the 3113B's are not (yet) bypassed, but we're working on it...

[4313B]

Schematic showing bypass cap locations in red:

Try AudioCap PPT Theta's from Parts Express and let us know what you think...

[boputnam]

Absolutley - full report to follow.

Well, I guessed it kinda, sorta right (a bold-faced lie... ).

So, now give this "Bypass Newby" the theory? The cap is a high-pass filter, right? So by adding a bypass cap of low value will it reduce the roll-off to the MF (and likewise to the HF)?

Maybe I shouldn't even be guessing here...

OH - and REALLY slick with the colored cut/paste stuff, Dr. Giskard! Impressive (and helpful!).

[boputnam]

Without any input (I know, a bad joke...), I am now wondering whether the bypass cap actually increases the roll-off(s), improving clarity. Maybe it's neither...

What is confusing me is these are in || and not in series.

Point me to something to read...?

I Googled this, which is tantalizing and intuitively sensible. I cannot vouch for it's integrity, but Kevin Ross has never lied to me before... http://www.seattlerobotics.org/encod...97/basics.html

Most compelling is: To summarize, the bypass capacitor is used to dampen the AC component of your DC circuits. By installing bypass capacitors, your DC circuit will not be as susceptable to ripple currents and voltages.

From Kevin Ross:

[4313B]

I've posted so much about bypass capacitors it makes me sick to think about it

You can read about them throughout the JBL library on this site.

http://www.lansingheritage.org/image...ome/page03.jpg

http://www.lansingheritage.org/image...460/page03.jpg

http://www.lansingheritage.org/image...-ti/page06.jpg

http://www.lansingheritage.org/image...est/page07.jpg

http://www.lansingheritage.org/image...xpl/page13.jpg

http://www.lansingheritage.org/image...312a/page3.jpg

http://www.lansingheritage.org/image...ries/page3.jpg

[boputnam]

Doh! My apologies, my (ex..) friend.

But, I apologized up-in-the-front for being a Newby. And, I admit to watching (some of...) this go by long ago, and thought it not relevant.

"As I learn, I find I am increasingly ignorant..." - surely some luminary other than me said this first!

Thanks, heaps for compiling all the Links! In an unintentional way, this vets my suggestion to DonMcR on Forum structure over the week-end. Oh well...

Off I go (but at dialup speed - DSL has crapped-out big time...)

[GordonW]

Thought I should add... just for the record, IMHO, the 120Ti is probably a better OVERALL speaker than the L112, due to the more neutral sounding upper midrange and highs. In fact, the ONLY speaker in the whole Ti line that I thought was a little bit "compromised", was the 240Ti, with it crossing the 104H right into the LE15... the lower mids were just a range that neither of those drivers seemed to want to do much with, IME. The 250Ti, with the 8" midbass, neatly solved THAT problem posthaste!!

However, that said, I'd like to see a mod on a 120TI, using a 104H-2 or -3 in there (paper cone), with whatever crossover tweaks would be advantageous to match it in with the system. To me, while the poly material used by JBL is head-and-shoulders better than that used by say, Dynaudio or Vifa drivers, it still doesn't have that "effortless lower mid snap" of a good felted paper driver, IMHO...

This brings up an idea, that I've been harboring in the back of my head for years... the "Super 250Ti". Say, a 2235 woofer, a 2118 or 2123 midbass, a 104H-2 (or in lieu of that, a Polydax/Audax 12P25 or PR17, ala GoldSound), and either the Ti dome or a 2404. Man, that with a 2404, with an appropriate crossover, could be deadly...

Regards,
Gordon.
who likes his midbass/lower mid transient attack behaviour set at KILL level... :-)

[4313B]

Well yeah, the 120Ti is definitely a "better" loudspeaker than the L112, but that doesn't mean everyone will like it better. The landscape is littered with "better" stuff that fell by the wayside for whatever reason. I know more than one person who'd take an old L100 over a 120Ti any day.

As for the 240Ti, it's all filter related. Each of the transducers are more than up to the task. It certainly isn't as "lacking" as say the old Athena S99 I happen to like it whereas my buddy wasn't inspired by it at all. I did build an L96/L112-type system that used the LE14H instead to compare against the 240Ti and it ended up kinda like the 120Ti versus the L112, both had their merits. It was just for fun because I had a bunch of drivers laying about but some woman ended up buying the pair because she thought they were great. Who'd a thunk it!

You can try a 104H-2/104H-3 in place of the 104H and see if you prefer it. They are all electrically similar with the 104H-2/104H-3 having slightly flatter response and the 104H having slightly lower distortion.

"who likes his midbass/lower mid transient attack behaviour set at KILL level"

Yeah well, I think everyone here knows by now what a fan I am of the 112/2108/2121/2122/2123/2202 transducers so I won't go on about them yet again

[4313B]

Originally posted by boputnam
Doh! My apologies, my (ex..) friend.

But, I apologized up-in-the-front for being a Newby. And, I admit to watching (some of...) this go by long ago, and thought it not relevant.

"As I learn, I find I am increasingly ignorant..." - surely some luminary other than me said this first!

Thanks, heaps for compiling all the Links! In an unintentional way, this vets my suggestion to DonMcR on Forum structure over the week-end. Oh well...

Off I go (but at dialup speed - DSL has crapped-out big time...)

Huh? Sorry if you feel I brushed you off. Perhaps it's because I get lazy? Anyway, here is my take on bypass caps:

From an acoustic point of view mylars to me sound very smooth and warm but they seem to lack excellent high frequency response. By bypassing them with polypropylene one gains the benefits of polypropylene's excellent high frequency characteristics and transient characteristics. By bypassing with polystyrene one gains the benefits of excellent high frequency characterisitics, depth and openness. By itself polystyrene can appear too laid back and lacking in transients. By itself polypropylene can seem too up front and strident. Mixing these dielectrics, as was done in the L250, 250Ti, and XPL200/XPL200A, seems to yield the best overall presentation.

From a cost/size point of view mylars are usually quite cost effective and they usually come in a smaller package than a poly.

Now here is something quite interesting:

"Do not use bypass capacitors in the signal path. A single capacitor for DC blocking/AC coupling creates a simple path with one time constant. The signal quality will be compromised if a bypass or multiple bypass capacitors are added to a signal path capacitor. Bypass capacitors were used in the past to bypass low quality film capacitors or electrolytic capacitors. The bypass was the lesser of two evils. With the advent of better quality film capacitors the need for a bypass capacitor was eliminated. Bypass capacitors create multiple signal paths with multiple time constants. These time constants are very short but they can still be heard as a smear or overall loss of focus."

I've discussed this with G.T. and in theory this is true. Unfortunately in practice it takes one helluva capacitor to live up to the task. Hovlands, Jensens, etc., they all claim to be "the one". They are all excellent, excellent capacitors but they are also all different in their sonic signatures. Given time and money, lots of money, one could sort out which of these "super caps" sounds best with which JBL loudspeaker system.

Let's take a 5234A with it's 100 uF NPE output caps. I can't imagine swapping it out for a film and foil poly cap. Primarily because it wouldn't fit in the chassis, secondarily because a 100 uF film and foil would cost damn near the same as the whole 5234A!. Solution? Pop in a very nice film and foil bypass cap and enjoy the result. The 5235 did just that. I challenge anyone to take a 5234A and a 5235 and listen for any smearing or loss of focus going on with the 5235 because bypass caps were employed. For that matter, I challenge anyone to take two pair of L250's, one pair without bypass caps, and one pair left stock, and A/B them with the hope of detecting smearing or loss of focus. Ain't gonna happen. And JBL transducers don't lie, they are extremely verbatim.

From a theoretical point of view, highly linear bypass capacitors (poly and teflon are extremely linear) help reduce the non-linearity (time lag aka hysterisis, dielectric absorbtion) found in larger, less expensive capacitors such as NPE's and mylars. Doing this helps reduce distortion and improve transient character. Biasing, or charge coupling, is an extension of this, helping to further reduce distortion.

I wish I could still find a couple of decent websites on dielectrics and bypass caps but I can't seem to any longer. There used to be a few.

[boputnam]

Thanks. I've re-researched all your posts and couldn't find much, per se, on the theory, so I 'preciate the post.

"Do not use bypass capacitors in the signal path."

I found that, too. Makes sense, but what surprised me was the effect is reportedly "audible". I was thinking the slight difference in time constant might not be as audible as was the improved HF response - i.e., the improvements mask the "noise". Maybe the effect is more audible in lower frequencies? I can't know.

I'd be real interested in seeing a response curve w/wo the bypass caps - I'm curious what is done, if anything, to the crossover slopes. Maybe there is no change...?

And, I'm mystified about caps in || versus series. My brain cannot cipher what them little electrons make of it all...

I know a few techs out there - I'll see what I can gather-up on this.

[4313B]

"Thanks. I've re-researched all your posts and couldn't find much, per se, on the theory, so I 'preciate the post."

Probably lost in the previous forums.

"I found that, too. Makes sense, but what surprised me was the effect is reportedly "audible". I was thinking the slight difference in time constant might not be as audible as was the improved HF response - i.e., the improvements mask the "noise". Maybe the effect is more audible in lower frequencies? I can't know."

I think one would have to compare the best of the "super" caps, bypassed and unbypassed, to come to any conclusion. When I think of doing all "super" caps in a 250Ti I cringe. It would cost over a thousand of dollars (why would one do the "super" caps and not the "super" coils as well). A better bet would perhaps be to do a partial and then biamp or triamp. Passive networks are just too goofy to spend such an enormous amount of money on. I'd rather put "super" caps as bypass caps into active gear where it makes a whole lot more sense and is significantly more cost effective. I don't know, maybe I'm wrong. JBL still sticks with poly bypassed mylar and NPE, even in their high priced systems, and they sound extremely fine.

"I'd be real interested in seeing a response curve w/wo the bypass caps - I'm curious what is done, if anything, to the crossover slopes. Maybe there is no change...? "

No change, you're talking adding a 0.01 uF to say a 4.0 uF which yields a 4.01 uF, the caps themselves vary more than that.

[boputnam]

from a PhD Physicist friend, and acoustician:

High-value caps are built in such a way that they have parasitic series inductance (and resistance too) that becomes "important" at high frequencies. These elements isolate the capacitor from the rest of the circuit at high frequencies, so the capacitor can't either filter or pass current as it is expected to do. Smaller-value caps have simpler structures and remain effective caps at higher frequencies. So putting a little HF cap in parallel with a big LF cap extends its usefulness to higher frequencies.

More as it comes in.