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View Full Version : Is it sacrelege? Am I evil? (long) - 4343 xover mods



4343mod
10-17-2003, 01:44 PM
I have a pair of 4343's, #13602 & 16644.
I bought these off of a friend who drove them with an Acoustat.
(Jim Strickland Trans-Nova amp, before Hafler)
This amp has a big DC pulse on power up. You could actually see the 15's flex outward for a moment! De-mag/re-mag service of the 15's at JBL in Northridge is needed to bring the sensitivity back to spec. Someday I will get to it.

I initially used them with (2) 350W Jeff Rowland Model 7 monoblocks for a year or so, when a horrible thing happened. The cheese rotary switch on the left monitor started shorting at very high levels. The first 2 or 3 times, the Rowland would step into standby, like a thoughtful amp should. Then late one night when I was touching the face of god, inraptured in sonic nirvana, it happened again, and 1 output rail on the rowland went. (12) TO-3 transistors, toast. Rather send the 120-pound amp back to Colorado for repairs, I sold them both as-is to a local dealer. What a shame.

That was the last straw. An incredible system, with almost limitless dynamics taken down by a $.50 part. Yes, these are rated at 150W, and saw 300+W regularly. Very convincing reproduction of concert levels! No, this disaster would never have happened with flea SE tube amps, I know. And I wouldn't need a towel next to the listening chair, either!

It became evident to me that the design of drivers and cabinet were first rate, (obviously) and that JBL cut corners on hardware and internal componets. I, C, and R in the XO's were not up to what these speakers could and did deliver. the (2) 2 Ohm Ohmite series resistors in front of the 2420's were powdered grey from overheating, and that POS rotary switch in the binding post plate was blasted as if it saw arc from a MIG welder. All level controls were ALWAYS set to max; to turn them down, you might as well put cotton in your ears or listen with the flu.

IMO, R is sonically destructive in a crossover. It should be used as little as possible, unless you like a veil between you and the music. Pots are the worst; fixed value parts should always be used when possible.

Now, having seen the crossover schematic, and tanking up ideas with a friend, it became clear the XO slopes were more for withstanding abuse and protecting the horns from distorting, poor quality, low powered SS amps, and less for clean transmission of signal. The 2 big caps in each XO were 'Lytic cans! 25 year-old chemical capacitors are not what premium sound is about! What if I made purist 1st order XO's with beefy, quality (if not premium) parts?

On to the debauchery!
I removed the OEM crossovers, wire, binding posts & plates. I disconnected the pots, though they are still in the cabinets, acting as hole plugs. I made a couple of post plates to accomodate (4) pairs of posts each. These posts are wired directly to the drivers. I then made a couple prototype XO's with air core inductors, Solen metalized film caps, and Mills NI resistors. Some non-NI resistors have found their way into the circuit, as padding for the 2420's. I use a NOS Centralab rotary switch on each channel to select different I values across the 2420, ususally set to .15 or .20mH. All wiring is point2point with Wonder Solder. Wire is garden variety Belden 16 gauge, except the LF circuits, which are Belden 14 gauge.

This arrangement allows for single, bi, tri or quad amping, as well as *gasp* active filtering with an outboard device.

Using the (6) OEM T-nutted holes on the back of the cabinets, I put screws through from the inside, thereby giving me threaded studs projecting from the back. The XO boards are mounted on these studs. No cutting, drilling, or other permenent changes were made to the cabinets. Everything is reversible.

On to the sound!
There is not 1 area of reproduction that has not been improved with these changes. If you have heard 4343's in OEM form, all I can say is imagine upgrading all of your electronics and cables up a couple of levels. That approaches the magnitude of improvement wrought by this. The Bob Harley analogy of "looking through several dirty windows then through 1 clean one" applies here. Macro dynamics have not changed much, but the micro dynamics, the little sparkles and shimmers of detail are stunning. I can hear into the images so much farther and with greater accuity than ever before. The speed of attack and decay is astonishing! Those that have not heard a 2420 horn with a single cap and resistor in series are missing something.

The bass response is more natural. Going from a 2nd order slope with an old, dried up 120uF 'lytic cap and tiny 20 gauge, 5uF inductor to 1st order with a 16 gauge, 9mH ERSE inductor is amazing. The boxiness is gone. The tonality and weight has taken shape like never before. The 15's play louder with less coloration. And the 15's are not even performing at spec sensitivity! Why would anyone use electrolytic caps in a high performance XO? And after 25-30 years, do you think the 120uF value is still stable? No way.

All I can say is the OEM XO's are slow, veiled, garbled, soft JUNK.
What a travisty to put this in front of such wonderful Alnico compression drivers.

I welcome any JBL enthusiast in the Los Angeles area to drop by and have a listen. It may be a sin, but it sounds Soooo good.
Any comments, slander or suggestions are welcome!

Thanks for reading this, Andy Bacon

System info:
244VAC, 2-pole breaker out of a 100A load center into
PowerStat 260V, 30A Variac, stepped down to 220VAC into
Topaz/Square-D 5kVA Ultra-Isolator line noise supressor (transformer) lifted ground, ~120VAC into....

Meridian 588 24-bit CDP, balanced out
Harmonic Technology TruthLink, XLR
Classe' CP-60 pre, balanced out
Harmonic Technology TruthLink, XLR
Crown Studio Reference1 or Krell KSA-200S
Analysis Plus Oval9
JBL 4343 Modded Macro Monitors!

boputnam
10-17-2003, 02:41 PM
Originally posted by 4343mod
What if I made purist 1st order XO's with beefy, quality (if not premium) parts?

On to the debauchery! Whoa... Impressive, and beautiful syntax, besides ! ;)

Any chance you could post a schematic of the final XO, and what slopes you elected to use?

I would love the TasteTest, and will take the offer if I get close enough. Much to think about with my 4345's - regretably, for now I can only imagine the improvements you describe... :( , even though I think I lack for nothing! :)

I think I'm getting that "Audiobeer Sensation"... :eek:

4343mod
10-17-2003, 03:42 PM
I will post the OEM schematic that I got from JBL (don't remember what the model number is for the 4343 crossover) and my 1st order schematic when I find them. They have been burried and have been through 2 moves since I made the changes. I know they are around here somewhere! :)

Thanks, Andy

Ian Mackenzie
10-17-2003, 04:03 PM
Andy,

Excellent work and I admire Can Do Attitude, Enjoy.

Yes, the cheap wire wounds ceramic power resisters scrub the sound somthin horrid compared to the Mills.

Caps have also come along way in the past 25 years and I suspect your newer caps certainly grace the results you now have.

I would turf the 120 uf electros (they sound cloudy & soft) and others and replace with a Solen or AEON and bypass with film & foil for starters, Hovland is better again but need to redraw on your mortgage got those.

I accept 1st order slopes do have better transient transfer function and I hear this in my Century 100's but not sure on the final result with the 4343 response.

Bo's 4345's xovers and my soon to be complete 4345 diy have tapped inductors to eliminate the fixed pads and power disipation issues.

I find the variable faders however are useful for fine tuning the balance though, particularly when you have 4 drivers to trim and wifey who likes to move your cabinets around for the visitors in advance. The newer 100 watt faders from PartsExpress appear to be very good quality, but have not taste tested with Mills in comparison (nichrome wire vs well wire of some sort??)


What is the Analysis Plus Oval9?

Have fun......

Ian





:smthsail:

JonFairhurst
10-17-2003, 04:11 PM
A sin? No. More like an act deserving sainthood.

Painting black and white cow colors on a Paragon is a sin. Putting the best available components under the hood just makes the best use of an already great speaker.

4313B
10-17-2003, 05:59 PM
"Painting black and white cow colors on a Paragon is a sin."

Ooops! :slink:

Guido
10-17-2003, 06:04 PM
Originally posted by 4343mod
I welcome any JBL enthusiast in the Los Angeles area to drop by and have a listen. It may be a sin, but it sounds Soooo good.
Any comments, slander or suggestions are welcome!

Thanks for reading this, Andy Bacon



For me it's too far to test it :D

Anyway thanks for that post. Could you help us with a schematic of your mod X-over?

This would be highly appriciated for shure!

4313B
10-17-2003, 06:09 PM
I would love to hear a pair of biased 4343B's :yes:

There has to be a way to get the good caps at a decent price. A Dayton 3.0 uF MPP goes for $1.67 and does sound a bit better than the Solen MPP that goes for $1.95 but the AudioCap PP&F that goes for $18.64 just blows them both completely away. It's just such a high price to pay, especially if you bias them. :( Just off the top of my head I would imagine a pair of biased 4343 networks would run nearly a grand?

Tom Loizeaux
10-17-2003, 06:19 PM
I found your post on replacing the crossovers in your 4343s very interesting - since I have recently aquired and re-habbed a pair myself. Following advice I got here on the JBL Forum, I added bypass film/foil caps throughout the crossovers. I also only run these in the bi-amp mode, therefore going around the largest caps.
I did not do a "before/after" test, but I find the results very satisfying.
I wonder how much more detail and accuracy I might still find if I completely re-did the crossovers from scratch.
Wouldn't putting jumpers accross the rotary switches, replacing all the caps and resistors, and hard wiring past the pots do the same job?

I'm interested in hearing responses.

Tom

Guido
10-17-2003, 06:19 PM
Hey Giskard,

is this what you call a AudioCap PP+F ?

I buy 3,3 uF for approx. 8 USD.

If you have a bigger order then maybe I can help.

4313B
10-17-2003, 06:26 PM
Hi Guido,

AudioCap (http://www.partsexpress.com/pe/showdetl.cfm?&User_ID=16005983&St=4526&St2=-43275473&St3=-77728599&DS_ID=3&Product_ID=16025&DID=7)

They are from the Reliable Capacitor (http://www.capacitors.com/index.html) company.

*****

The price for them is just too high, especially for 10% tolerance, but they sound so damn fine.

I've been told the Audyn-Cap is quite good and $8 sounds much better. :p

Guido
10-17-2003, 06:45 PM
Normal price here is appr. 14 USD.

So if anyone needs big caps in higher amount (think of the shipping Europe > USA) then I will be glad to help.

Just drop an PM

mikebake
10-17-2003, 08:16 PM
Ian, what Parts Express fader are you refering to? Perhaps a link?

Ian Mackenzie
10-18-2003, 01:45 AM
Mike,

Partsexpress.com

Item 260-265 which I sourced locally

Ian:smthsail:

Ian Mackenzie
10-18-2003, 01:48 AM
These guys have some values of the Hovlands on special:

They are a smooooooth wipped cream on the slots and affordable in those values

http://www.welbornelabs.com/hov.htm

Ian:smthsail:

4313B
10-18-2003, 03:03 PM
I see no problem at all with trying out 2003 technology in your old JBL loudspeakers. Just a few responses to some of your statements and answers to some of your questions though -

"JBL cut corners on hardware and internal componets. I, C, and R in the XO's were not up to what these speakers could and did deliver."

They were fine for that era.

"IMO, R is sonically destructive in a crossover. It should be used as little as possible, unless you like a veil between you and the music."

Capacitors and inductors are far more troublesome than resistors. They, and not resistors, are the truly pathetic passive components.

"it became clear the XO slopes were more for withstanding abuse and protecting the horns from distorting"

The 4343's are Studio Monitors. The higher order filters do offer increased protection and bandwidth limiting but they also offer greater control over dispersion characteristics and that is one of the design criteria of the Studio Monitors. They didn't want vertical dispersion running completely amok. More recent JBL Studio Monitors employ 24 dB/octave filters in order to tightly control each transducer within its intended bandwidth.

"Why would anyone use electrolytic caps in a high performance XO?"

Because they were a viable solution 25 years ago. Just like using a 2231 or 2121 was viable. The newer 4344 and 4345 used newer technology and paralleled mylar capacitors bypassed with polypropylene capacitors to get the necessarily large values. They also used the newer 2235 and 2122. The electrolytic capacitors, the 2231 and the 2121 were no longer viable solutions for the task at hand.

"And after 25-30 years, do you think the 120uF value is still stable? No way."

And neither are the compression diaphragms, nor the spiders and compliances, nor the magnetic assemblies. Stuff wears out.

"All I can say is the OEM XO's are slow, veiled, garbled, soft JUNK."

They were excellent for their era.

"What a travisty to put this in front of such wonderful Alnico compression drivers."

It isn't a travesty, the 4343 was nothing short of excellent for it's era.

boputnam
10-18-2003, 03:27 PM
Originally posted by Giskard
And neither are the compression diaphragms, nor the spiders and compliances, nor the magnetic assemblies. Stuff wears out.
Yup.

Giskard - a great post. :yes: An excellent perspective on the Studio Monitor and it's evolution. You've got an irreplaceable and invaluable experience with JBL stuff. :thmbsup:

Mr. Widget
10-18-2003, 03:53 PM
I agree that Giskard's post addresses many points that have been discussed on various threads, but does so very clearly and succinctly.


Originally posted by Giskard


"All I can say is the OEM XO's are slow, veiled, garbled, soft JUNK."

They were excellent for their era.




On the one point quoted above I would only like to add that there is no way to truly compare an original 4343 or any other vintage speaker to a newly modified one since they do wear out.

scott fitlin
10-18-2003, 04:10 PM
Its a fact there are technically superior resistors, capacitors, and semiconductors available today then there were just 20 years ago!

What JBL was doing 20 years ago and beyond was in fact some of the VERY BEST available at any cost!

But consider this! Vintage speakers used the best parts available at the time.

Vintage speakers were voiced for the music and electronics of the time!

As has been said already, Stuff wears out! Even if you had a BRAND NEW never been used 43xx pair of speakers, the caps dry out, the surrounds dry a bit!

Considering how sought after, and that they still around at all, JBL vintage designs are, its a serious testament to how GOOD JBL was and still is!

JonFairhurst
10-18-2003, 07:57 PM
>> "IMO, R is sonically destructive in a crossover. It should be used as little as possible, unless you like a veil between you and the music."

>"Capacitors and inductors are far more troublesome than resistors. They, and not resistors, are the truly pathetic passive components. "

You're both right. The Cs and Ls are problematic. Why? Because of non-linearity, and... parallel and series parasitic resistance.

The worst resistance is the resistance that isn't shown in the schematic.

4313B
10-18-2003, 09:51 PM
Well if placing the resistor pads in the passive crossover network bothers you then use active filters and their level controls instead.

*****

"The worst resistance is the resistance that isn't shown in the schematic."

Yeah, the resistance she puts up when you tell her you are thinking about buying a pair of 4350's to put in the living room can be quite daunting.


"What JBL was doing 20 years ago and beyond was in fact some of the VERY BEST available at any cost!

But consider this! Vintage speakers used the best parts available at the time.

Vintage speakers were voiced for the music and electronics of the time!

Considering how sought after, and that they still around at all, JBL vintage designs are, its a serious testament to how GOOD JBL was and still is!"


Good points Scott. Especially the one about the voicing as we all know how much empirical design goes into a typical JBL loudspeaker.

4343mod
11-11-2003, 12:55 AM
I feel so bad for not being able to post back sooner- my ISP went south, my PC's HD siezed, and my GF crashed my car all in the last 4 weeks. Damn sunspots! :P

I thank you all for your thoughtful comments and compliments! I didn't expect praise! At all! Thanks again!

My bad, the largest value in the OEM XO is 72uF, not 120 as I stated. I confused the 4343 with another non-JBL monitor.

boputnam, Guido,
Here is the 1st order schematic I threw together in Visio2000. The values given are the actual ones I'm using. The OEM XO schematic is given elsewhere on this site, and is the same document I have.

Ian Mackenzie:
I'll include a pic of the Analysis Plus Oval9.

Tom Loizeaux:
Your suggested mods to your existing crossovers would net the best results from them, but IMHO 1st order slopes offer the best time/phase response and the most coherent images. Lower power handling is the only downfall. (IMO!)

Giskard:
Yes, I and C is more troublesome than R, but my point was that I and C can't be discarded when building a filter for a wide-bandwith driver. IMO it is better to get I and C as close as possible, thereby dismissing the need for excessive R. And potentiometers are a convienence, but make for a poor resistor compared to a fixed value.
Your point about diaphrams, spiders, etc wearing out is well taken, but their degeneration is acelerated when USED. Chemical caps degrade over time on the shelf. If you don't play your speakers, the moving parts pretty much don't wear. Chemical caps start to degrade the day their made and continue to do so regardless of use or lack of.
JBL did cut corners on their parts selection, and saying the parts used were "viable for the time"...well, Bose and Kenwood can say that about the junk they make today, can't they? Paralleled film caps could have been used in 1976 for the larger values, and the horrid performance at audio frequencies and the poor life of 'Lytic caps was well known even then. The 4343 was to be a no compromise design, yet it was compromised. :( My friend insists the selection of the 'Lytics was purposefull, and the inherent distortion, coloration, whatever one likes to call it, was intentionally used to soften and warm up the bass and mid bass response. Maybe.
The 4343 was indeed nothing short of excelent for it's era, but it could have and should have been made better. The POS $.50 rotary switch for instance should have been pitched and a quality one used instead.

{{hard to see here, but the I values on the HF rotary switch are .1, .15, .23 and .3 uF.}}

4343mod
11-11-2003, 01:14 AM
Here ya go Ian :)

Ian Mackenzie
11-11-2003, 01:43 AM
Wow,

Will ya look at that dang python speaker lead.

That's the sort of snake you would only find in Bo's backyard..muhahahah.

Seriously, Can you give some details? It looks like a flat braid not unlike some heavy auto audio cables.

Ian



:eek:

boputnam
11-11-2003, 07:52 AM
Originally posted by 4343mod
Here is the 1st order schematic I threw together in Visio2000. The values given are the actual ones I'm using. Hey, Andy... Welcome back! :wave:

Sounds like some real trouble you been through! :duck:

Looking at the schematic, two things?

- you're running the 4343 passive? Not biamped, right? :hmm: What is the crossover-point between the 2231A and the 2121?

- the original network had the LF out-of-phase with the remainder of the transducer assemblage. Have you tried that, but prefer them all "in phase"? Just curious (and it's been a while since we had a polarity thread... :rotfl: )...

4313B
11-11-2003, 10:30 AM
"Yes, I and C is more troublesome than R, but my point was that I and C can't be discarded when building a filter for a wide-bandwith driver. IMO it is better to get I and C as close as possible, thereby dismissing the need for excessive R. And potentiometers are a convienence, but make for a poor resistor compared to a fixed value."

JBL felt the same way and began using fixed resistors in the Lxxt and Ti series loudspeakers. That was sometime in the early 80's.

"Your point about diaphrams, spiders, etc wearing out is well taken, but their degeneration is acelerated when USED. Chemical caps degrade over time on the shelf. If you don't play your speakers, the moving parts pretty much don't wear."

I've got a dozen drivers sitting here looking at me that JBL had stored in a warehouse that have sagging suspensions and rotted compliances. They are brand new, never been used, and very expensive transducers. JBL just credited me for every last one of them.

"JBL did cut corners on their parts selection, and saying the parts used were "viable for the time"...well, Bose and Kenwood can say that about the junk they make today, can't they? Paralleled film caps could have been used in 1976 for the larger values, and the horrid performance at audio frequencies and the poor life of 'Lytic caps was well known even then."

JBL began using poly bypass caps in ~ 1980-81 with Consumer systems and ~ 1981-82 with Pro systems. The L110A is generally regarded as the first production loudspeaker system to employ the topology.

"The 4343 was to be a no compromise design, yet it was compromised. My friend insists the selection of the 'Lytics was purposefull, and the inherent distortion, coloration, whatever one likes to call it, was intentionally used to soften and warm up the bass and mid bass response. Maybe."

Like all JBL systems the 4343 was finished up with significant empirical fine tuning. All loudspeaker systems are a balance/compromise. The laws of physics demand it.

"The 4343 was indeed nothing short of excelent for it's era, but it could have and should have been made better."

Not at it's price point.

"The POS $.50 rotary switch for instance should have been pitched and a quality one used instead."

I believe that switch was upgraded to a $.75 switch in the 4344/4345/4430/4435 systems.

4343mod
11-11-2003, 10:33 AM
Here is a LONG read from their site, www.analysis-plus.com
They have graphic simulation analysis snapshots on the site; might want to check them out.

White Paper on Cables (Report 981)

A Measurably Better Audio Cable
Analysis Plus Inc., provides leading-edge research and technology in the field of electronic systems and components. Many of our customers are major names in high-end audio and home theater equipment. These manufacturers rely on us for our skills, reputation, and expertise during all phases of product development.

Our recent innovations in audio cable design were prompted by the realization that we could substantially improve the state-of-the art in cable design and performance. Along with our background in electrical engineering, we are also audiophiles and wanted to create the best cables available anywhere--period!

What Makes a Good Audio Cable?
While testing audio cables for several well-known manufacturers, we learned that their criteria for what supposedly made one cable perform better or worse than another was remarkably inconsistent. One manufacturer's claims countered and negated the claims made by a different manufacturer. Yet each one purported to be the best! As we studied the available literature, we quickly realized that the source of the problem was a lack of hard evidence supporting all the hype. None of the manufacturers offered documented, measurable evidence that it was producing a superior cable. Instead, we found claims of allegedly superior components or materials used in cable construction.

For example, a few leading manufacturers claimed that the most important factor for a cable was low capacitance, using the justification that cable capacitance shunts upper frequencies to ground. In order to lower the capacitance, these companies increased conductor spacing to simultaneously achieve a goal of increased inductance. This approach had drastic side effects, however. Merely decreasing capacitance without taking other realities of signal transmission into consideration increased the noise pickup and introduced a blocking filter. Both of these effects would obviously degrade sonic performance rather than improving it.

Another cable manufacturer advertised that its cable "employs two polymer shafts to dampen conductor resistance", but offered no evidence to prove it. Still another audiophile company claimed that because its cable was flat, "with no twist, it has no inductance". In general, inductance can indeed be reduced by making conductors larger or bringing them closer together. However, physics shows that, in reality, no cable can be built without some level of inductance, so this claim is without scientific merit.

To convey musical information effectively, a cable must provide a structured, low impedance path for the desired signal. This became our goal at Analysis Plus, Inc. We began by applying our expertise in electromagnetic computer simulation and design to rigorously test and study a broad range of audiophile cables currently on the market. Based on what we learned, we then set about designing our own approach to audiophile cables, relying on solid, measurable data rather than subjective claims.

Cylindrical Cable Conductors and Skin Effect
Most of the popular loudspeaker and musical instrument cables on the market employ cylindrical (a.k.a. round-diameter) cables as conductors. Unfortunately, cylindrical cable designs have a number of serious drawbacks, including current bunching, skin effect phenomenon, and frequency effects that lower the performance of the cable.

It's a common misconception to think about electrical transmission in cables in terms of direct current (DC) alone. Even experienced electrical engineers frequently ignore the ramifications of frequency on cable performance. In the case of DC, current is indeed uniformly distributed across the entire cross-section of the wire conductor, and the resistance is a simple function of the cross-sectional area. Adding the frequency of an electrical signal to the equation complicates the situation, however. As frequency increases, the resistance of a conductor also increases due to skin effect.

Current density at DC Current density at higher frequency
Skin effect describes a condition in which, due to the magnetic fields produced by current following through a conductor, the current tends to concentrate near the conductor surface (see figure 1b). As the frequency increases, more of the current is concentrated closer to the surface. This effectively decreases the cross-section through which the current flows, and therefore increases the effective resistance.1

The current can be assumed to concentrate in an annulus at the wire surface at a thickness equal to the skin depth. For copper wire the skin depth vs. frequency is as follows:

60 Hz = 8.5 mm, 1kHz =2.09 mm, 10 kHz =0.66 mm, 100 kHz =0.21 mm.

Note that the skin depth becomes very small as the frequency increases. Consequently, the center area of the wire is to a large extent bypassed by the signal as the frequency increases (see Figure 2b). In other words, most of the conductor material effectively goes to waste since little of it is used to transmit the signal. The result is a loss of cable performance that can be measured as well as heard.

Current Bunching
Current bunching (also called proximity effect) occurs in the majority of cables on the market that follow the conventional cylindrical two-conductor design (i.e., two cylindrical conductors placed side-by-side and separated by a dielectric).

When a pair of these cylindrical conductors supplies current to a load, the return current (flowing away from the load) tends to flow as closely as possible to the supply current (flowing toward the load). As the frequency increases, the return current decreases its distance from the supply current in an attempt to minimize the loop area. Current flow will therefore not be uniform at high frequencies, but will tend to bunch-in. This can be seen in Figure 2b, which illustrates typical current density distribution in a cross-section view of a pair of cylindrical 12-gauge wires at 20 kHz. The density shadings are shown in color, with red being the highest current density and purple the lowest current density.

The current bunching phenomenon causes the resistance of the wires to increase as frequency increases, since less and less of the wire is being used to transmit current. The resistance of the wire is related to its cross-sectional area, and as the frequency increases, the effective cross-sectional area of the wires decreases. In order to convey the widest frequency audio signal to a loudspeaker, you want to use as much of the conductor cross-section as possible, so excessive current bunching is extremely inefficient.

Disadvantages of Rectangular Conductors
As a means of bypassing the skin effect and current bunching problems associated with cylindrical conductor designs, some cable manufacturers have developed rectangular conductors as an alternative. These designs typically use a one-piece, solid core conductor.

Computer simulation showing the magnitude (volts/meter) of the electric field between two solid rectangular conductors. The conductors have a cross section area equivalent to a 10 gauge conductor. The spacing between the two conductors is 2mm with a voltage of +1 volt applied to the top conductor and -1 volt applied to the bottom conductor.

Computer simulation showing the magnitude (volts/meter) of the electric field between two hollow oval conductors. The conductors have a cross section area equivalent to a 10 gage conductor. The spacing between the two conductors is 2mm with a voltage of +1 volt applied to the top conductor and -1 volt applied to the bottom conductor.

A solid rectangular conductor of this type is undesirable because the sharp corners produce high electric field values that over time can break down the dielectric, causing a failure of the cable (see Figure b). In general, cables with solid conductors are prone to shape distortions and kinking due to their poor flexibility. This becomes an especially important issue with rectangular cable designs. The sharp corners from rectangular conductors tend to chafe the cable dielectric if the cable is repeatedly flexed or put under stress, and this chafing can lead to a short that could conceivably damage your loudspeakers.

The Hollow Oval Cable Solution
After many computer simulations and other exhaustive tests, the engineers at Analysis Plus, Inc., reached an innovative solution that flew in the face of conventional wisdom on audio cable geometry. Our engineers determined that a hollow oval cable constituted the best possible conductor design. Here's why.

The primary advantage of an oval conductor design rather than cylindrical conductor geometry is that the oval shape allows more of the return current to be closer to the outgoing current, thus reducing the negative effects associated with excessive current bunching.

Figure 1 illustrates that at DC the current is uniformly distributed across the cross-section of the wire, but as the frequency gets higher, the current is distributed near the surface. Since the center part of the conductor is not used at high frequencies, we can simply eliminate it. By using a hollow conductor, we help minimize the change in resistance with frequency and the cable becomes more efficient.

Advantages of a Braided Conductor
Along with the innovative hollow oval conductor design in our Oval cable product line, we also determined that a braided conductor was superior to solid core conductors for two significant reasons.

4343mod
11-11-2003, 10:34 AM
Characteristic Impedance Complexity
Another parameter that is critical in cable design is characteristic impedance. But because of its complexity, this important factor is often misunderstood.

The characteristic impedance of a cable is given by Z = [(R + jwL)/(G + jwC)]1/2 where R is the series resistance, L is the series inductance, G is the shunt conductance, C is the shunt capacitance, and w is the angular frequency (w = 2pief).

Note that this is not a simple number for a cable, but one which changes with frequency. It is also important to note that R, L, G, and C also change with frequency, making the impedance of a cable even more frequency dependent.

Z is a complex number, and it is common practice in the cable industry to simplify the situation by assuming a loss less transmission line and, in turn, assuming that R and G are zero. While this may be a valid approximation at high frequencies, it is not valid at low audio frequencies if you plan to construct an accurate model of a cable.

For example, stating that a speaker cable has a constant, characteristic impedance of 10 ohms across the entire frequency range of 20 to 20,000 Hz is a drastic oversimplification that, in the end, is simply untrue. The same type of statement is also inaccurate when applied to loudspeakers, as the table below shows. A speaker only has a constant impedance of 8 ohms at a single fixed frequency. To state otherwise is to ignore the complexity of impedance changes as signal frequency changes.

Minimizing Impedance Mismatch
Our Oval cables minimize frequency changes and boast a low impedance to reduce reflections at the high end of the audio frequency range.

Conventional cylindrical cable, due to its geometric limitations, typically has an impedance of about 100 ohms at the high end of the audio frequency band, thereby causing an impedance mismatch at high frequencies. In an attempt to eliminate impedance mismatch, some audiophile cable companies introduce passive components into their cables. However, these components can do more harm than good by introducing another possible source of pollution (or distortion) to the signal.

As shown in Figure 3, Analysis Plus, Inc., Oval cables minimize the change in resistance with frequency. Our exclusive braided conductor, hollow oval design also minimizes the frequency dependence of the inductance L as shown in Figure 4. By minimizing current bunching and skin depth problems, we minimize unwanted distortion, maximizing transparency and realism.

Frequency Blurring
To minimize frequency blurring, it is important that the speaker cable parameters do not change with frequency. Ideally, the resistance and inductance would remain constant as the frequency of the signal changes. Figure 3 and 4 show that Analysis Plus, Inc., Oval cable minimizes the change of R and L with shifts in frequency, thus minimizing frequency blurring.

Wave Good bye to EMI
Electromagnetic Interference (EMI) is commonly encountered when multiple electronic devices are operated in close proximity to one another. Almost everyone has heard or seen the interfering effect of a vacuum cleaner, lawnmower engine, hair dryer, or blender on a radio or television. These are examples of EMI, which can also significantly degrade the performance of a hi-fi system. How does EMI get into your system? AC wiring is one route. But even when this entry point is eliminated by using power conditioning components, EMI still gets into the signal path. Speaker cables are frequently the culprit.

As discussed on page 29 of Henry W. Ott's Noise Reduction Techniques in Electronic Systems, loudspeaker cables generally comprise the longest parts of a system and therefore act as antennae that pick up and/or radiate noise.

While all real-world cables fall short of ideal behavior in eliminating the problems of EMI, our Oval cables perform closer to the ideal than any other cable currently on the market. To reduce EMI, it is important to have a low inductance. Our Oval cables exhibit low inductance which helps reduce noise and therefore improves the final sound.

Figures 5 and 6 show the superiority of Analysis Plus cable to other cable designs. The two plots in the graph represent measured data taken using a digital oscilloscope and a signal generator to produce a test signal. The purple waveform shows the source signal at the amplifier. The green waveform shows the signal after transmission to the speaker through a cable. For best performance, a cable should not distort the signal--the source signal and the signal at the speaker should show similar if not nearly identical waveforms.

Imagine how much music you have been missing simply due to inferior cable!

The Best Test Instrument--Your Ears
Finally, we turn our attention to human hearing. After all, our end goal at Analysis Plus, Inc., is to bring our customers the best sound possible, and your ears are the ultimate judges of our success.

The faintest sound wave a normal human ear can hear is 10(-12) Wm(-2). At the other extreme of the spectrum, the threshold of pain is 1 Wm(-2). This is a very impressive auditory range. The ear, together with the brain, constantly performs amazing feats of sound processing that our fastest and most powerful computers cannot even approach.

As long ago as 1935 Wilska 2 succeeded in measuring the magnitude of movement of the eardrum at the threshold of audio sensitivity across various frequencies. At 3,000 Hz, it takes a minimal amount of eardrum displacement (somewhat less than 10-9 cm or about 0.01 times the diameter of an atom of hydrogen) to produce a minimal perceptible sound. This is an amazingly small number! The extremely small amount of acoustic pressure necessary to produce the threshold sensation of sound brings up an interesting question. Does the limiting factor in hearing minimal level sounds lie in the anatomy and physiology of hearing or in the physical properties of air as a transmitting medium?

We know that air molecules are in constant random motion, a motion related to temperature. This phenomenon is known as Brownian movement and produces a spectrum of thermal-acoustic noise.

In 1933, Sivian and White3 experimentally evaluated the pressure magnitudes of these thermal sounds between 1kHz and 6 kHz. They observed that throughout the measured spectrum the root-mean-square thermal noise pressure was about 86 decibels below one dyne per square centimeter. The minimum root-mean-square pressure that can produce audible sensation between 1 kHz and 6 kHz in a human being with average hearing is about 76 decibels below one dyne per square centimeter, but in some people with exceptionally acute hearing may approach 85 decibels.

These figures indicate that the acuity of persons possessing a high sensitivity of hearing closely approaches the thermal noise level, and a particularly good auditory system actually does approach this level. Furthermore, it is not likely that animals possess greater acuity of hearing in this spectrum, as their hearing would also be limited by thermal noise.

What this means is that the human audio system is extremely sensitive, and that small things like cable design are important to maximize the listening pleasure. At Analysis Plus, Inc., we're committed to doing our part by bringing you the best-sounding audiophile cables on the market.

4343mod
11-11-2003, 10:53 AM
Giskard:
I've got a dozen drivers sitting here looking at me that JBL had stored in a warehouse that have sagging suspensions and rotted compliances. They are brand new, never been used, and very expensive transducers. JBL just credited me for every last one of them.

Ah yes, foam surrounds, of course. Thanks again for foiling my seat of the pants intuition with your detailed knowlede of the period. Giskard, you are a credit to this forum! :D

boputnam:
I am running them passive with 1 amp. I believe the pass between LF and MF is close to 200-250 Hz, thogh I have not tested it. I have not tried inverting phase on any of the drivers, BUT I WILL now that you mention it.

An aquaintance well versed in JBL drivers and DIY SET amps gave me the values to try, and that's what I'm using. I did ask him about inverting phase on the band pass sections, as many designers do, and he dismissed it. That was about 2 years ago. His name is Blaine Spears, and since he is not a computer user, I'm sure he isn't on this forum. Pitty, he has tons of knowedge and a great design and listening ethic, IMO. But I'm going to try it, it will take about 5 minutes to switch back and forth. Thanks for the tip. -Andy

Mr. Widget
11-11-2003, 11:03 AM
" What this means is that the human audio system is extremely sensitive, and that small things like cable design are important to maximize the listening pleasure. At Analysis Plus, Inc., we're committed to doing our part by bringing you the best-sounding audiophile cables on the market."




Hmmmmmmmmmmm.

4313B
11-11-2003, 11:17 AM
"human audio system is extremely sensitive"

Actually the human audio system is for shit. It is barely adequate for basic survival and that's about it.

4343mod
11-11-2003, 11:35 AM
Originally posted by Giskard
"human audio system is extremely sensitive"

Actually the human audio system is for shit. It is barely adequate for basic survival and that's about it.

That is right, and why we built shelter and moved indoors, leaving the wild to the beasts. Out there, we were merely food!

Whoa, this thread has gone anthropo! :lol:

4313B
11-11-2003, 12:02 PM
We really do strive to morph various threads into shadows of their former selves :p

Now, about those lions, tigers, and bears...

pangea
11-11-2003, 02:46 PM
Originally posted by 4343mod

...{{hard to see here, but the I values on the HF rotary switch are .1, .15, .23 and .3 uF.}}

- 4343mod

Hi, I have two questions, if you'd like to answer them.

1. You mean mH, not .1, .15, .23, .3 uF?
2. The 2420 is a 16 Ohm driver, right, and do you know if I can use it with a 2445J?

BR
Roland

4343mod
11-11-2003, 05:22 PM
Originally posted by pangea
- 4343mod

Hi, I have two questions, if you'd like to answer them.

1. You mean mH, not .1, .15, .23, .3 uF?
2. The 2420 is a 16 Ohm driver, right, and do you know if I can use it with a 2445J?

BR
Roland

Pangea- yes, I meant Mill-Henries. Duh-doowie! :banghead:

I thought the 2420 was a 16 Ohm driver, but the spare D16R2421 diaphrams I got from JBL measure resistance at around 6 Ohms. Maybe Giskard or someone can figure if 6 Ohms Resistance might = 16 Ohms Impedance? I'd guess the [16] in D16R2421 would mean 16 Ohms, but I dunno.

As far as 2445J goes, I don't even know what that is. Is that a horn assy? A lens? Giskard? :confused:

4313B
11-11-2003, 05:43 PM
The D16R2420 diaphragm (2420) is a "16 ohm" diaphragm and has a DCR of 5.9 to 7.0 ohms.

The D8R2421 diaphragm (2421A) is an "8 ohm" diaphragm and has a DCR of 2.9 to 3.5 ohms.

The D16R2421 diaphragm (2421B) is a "16 ohm" diaphragm and has a DCR of 5.9 to 7.0 ohms.

The D8R2425 diaphragm (2425H) is an "8 ohm" diaphragm and has a DCR of 2.9 to 3.5 ohms.

The D16R2425 diaphragm (2425J) is a "16 ohm" diaphragm and has a DCR of 5.9 to 7.0 ohms.

The D16R2445 diaphragm (2445J) is a "16 ohm" diaphragm and has a DCR of 7.3 to 8.6 ohms.

The horn loads the compression driver and affects the impedance. Different horns load differently.

4343mod
11-11-2003, 06:03 PM
Wow, so my 2420's aren't 2420 anymore, they are 2421B?
How does the OEM horn that is fitted to the 2420 respond to a D16R2421 diaphram? Sometimes I really do learn something new everyday...Like today! ;)

boputnam
11-11-2003, 08:31 PM
Originally posted by 4343mod
As far as 2445J goes, I don't even know what that is. Is that a horn assy? A lens? Giskard? :confused: I'm confused by your question (I should go back and review this Thread, but...) just to be sure you get an answer - the 2445J is a compression driver, with the large diaphram (factory titanium) that some feel is smoother than the smaller diameter siblings. JBL Pro - 2445J CD - Link (http://www.jblpro.com/pub/components/2445J.pdf)

Me? I'm quite fond of the 2421B's, with newly replaced diaphragms (D16R2421B), that I did only a few months back. :thmbsup:

Sweet. :)

Oh, and they take the identical horn/lens assembly, the 2391 JBL PRo - Acoustic Lens Family - Link (http://www.jblpro.com/pub/obsolete/Acoustic_Lens_Family1.pdf)

(NB: there is a typo in the spec sheet - that is the 2308 Lens...)

4343mod
10-10-2004, 03:53 AM
Well folks, been a long time... and things still work!
Not one driver burnout on the shallow slopes, and we do party hard sometimes.

I have been away from the board so long, too busy to breathe for WAY too long but now I have some me time & I aim to make some improvements! :)

Yes, it's time to start over again. The Solens & cheesey air cores are starting to sound kinda screetch, and the rotary switch will go, since I rarely go off .15 mH anyway. I'm pushing some shapes around in CAD again, with better chokes and caps, seperate bi-wired 12 dB/octave for the LF, some mild MF/HF value changes, and a simpler, more user friendly pad/shunt bridge for the Mills smear sticks. I'm going to try to reduce contact points and simplify cap/choke switching too.

This time we'll use Baltic Birch instead of Fir and it's going to probably look like a sloped cigar box, with 2 levels, resistors on top and everything else underneath.

2121 & 2231A: Can anyone recomend a source for recone besides JBL pro? They want way too much money to rebuild these, I think there are better (more sensitive) parts in the JBL family to replace these with anyway? Si or no?

4343mod
10-10-2004, 04:22 AM
Originally posted by 4343mod
I will post the OEM schematic that I got from JBL (don't remember what the model number is for the 4343 crossover) and my 1st order schematic when I find them. They have been burried and have been through 2 moves since I made the changes. I know they are around here somewhere! :)

Thanks, Andy

I found that original 3143 XO (4343) schematic & can scan & post it if anyone is still interested.

Earl K
10-10-2004, 07:28 AM
Hi

You might luck out and find what you need on eBay. For instance here's what turns up today on a search for a 2122H (http://search.ebay.com/JBL-2122h_W0QQsofocusZbsQQsbrftogZ1QQsocolumnlayoutZ3Q QfromZR10QQsotrZ2QQsosortpropertyZ2QQsosortorderZ2 ) .

A couple of good looking 2121h mids just sold this week for @ $ 155.00/pr .

Reconing a 2231 with the 2235 kit is the way to go . You increase the Xmax by trading in the .6" deep coil winding of the 2231 for the .75" deep coil of the 2235. The 2235h kit is a good value - available to authorized recone centers only.

<. Earl K

4343mod
10-10-2004, 12:18 PM
Earl,
Thanks for the tip on the 2235 kit. I'd like to get away from foam surrounds if at all possible. Maybe that means different drivers all together. Foam just doesn't seem to hold up to my environment too well.

Mr. Widget
10-11-2004, 10:42 AM
Originally posted by 4343mod
I'd like to get away from foam surrounds if at all possible. Maybe that means different drivers all together. Foam just doesn't seem to hold up to my environment too well.

Foam will last 10-15 years period.

All of the drivers that I can think of including those by other manufacturers that use rubber or a cloth surrounds do not have the LF extension of the 2235 and it's sensitivity. There are plenty of drivers that go lower, there are plenty that are more efficient, but the 2235 represents an excellent blending of these two factors.

If you are hell bent on getting away from foam surrounds, you can get a cloth surround 2225 kit for your woofers, but you will likely want to add a sub.

Widget

4343mod
10-11-2004, 03:31 PM
Thanks Widget.
Actually, I could sacrifice some extension for more sensitivity, then I would need less padding on the 2420, always a good thing in my book. I'm thinking subs are going to become essential anyway to get the levels I want <50 Hz. Is there a kit available that can offer ~100dB voltage sensitivity and the same power rating for these 2231 baskets? I was even thinking about going to 16 Ohm 15's and adding 2 more, and paralleling 2 for an 8 Ohm load and +3dB response, then working on a sub solution.

Thanks again for all the info guys! The JBL parts list & history is so vast, I'm impressed with your knowledge! All of you! :)

4343mod
10-11-2004, 03:37 PM
Oh, yes, regarding the life span of foam: I'm sure that is true. But how does one know that the kits one pays to have installed aren't NOS and been sitting on a shelf in a hot warehouse for 10 years? Then your "brand new" kits are already half way dead just from drying out on a shelf. Possible?

4343mod
08-01-2005, 12:28 PM
Bump! :p

Lancer
08-01-2005, 12:31 PM
Yes... It is possible...

Replace your drivers having foam surrounds with a 1500FE, ME150HS, or 1500AL. None go as deep as the 2231 or 2235 but they don't rot as fast either. EQ is the best bet to fill in the very bottom end when using those drivers. The LE14H-3 is the only driver I can think of right now besides the W1500H that can go real deep. The W1500H is probably not a great replacement driver for the large format 4-ways... well, on second thought, it might actually work with a 2122 and a lower crossover frequency...

ogmios
10-11-2005, 09:52 AM
I just got a pair of 4343 given to me. I've refoamed the 2121's sucessfully, they sound great. But the 2231's are weird. One is blown, but seems to be original cone. I know the baskets are original 2231, but the other 15" that still works has been reconed and I like it. I need help figuring out what it was reconed with.

Can anyone tell me which cone kit has a soft felt dust cap, and paper surrounds. The original 2231 I think has a hard dust cap and foam surround.

I love the subtle, gut wrenching thing it does, and I want to recone the bad 2231 as whatever the other one is.

My guess is 2225h, but does that have a soft dust cap?

Thanks, wonderful site, been lurking a few months.

Earl K
10-11-2005, 10:36 AM
Hi

(a) Recone your 2231s' as 2235s'. They'll give you the very best VLF from your 2231 frames . Yes they have foam surrounds, but as you said, you're experienced in replacing these things .

OTOH :
(b) If you truly believe that a speaker like the 2225 will give you the bass you like , then buy a pair on eBay ( this will cost about the same as a single 2225h recone ). This will be a less expensive education if it doesn't work out .
- The 2225 has a free air resonance set to one octave higher than the 2235 ( 40 hz versus 20 hz ) .

(c) Pics of your mystery speaker would help (some) the identification ( an electrical anlysis of its' TS parameters would be the best ) .
- The 2225 has a hard paper dust cap and the cone has many ribs ( just like the 2231 ).
- You may have some aftermarket recone kit of unknown origin .
- Look for any printed markings on the underside of the black cone. They'll help the reconers here identify the recone kit .
- It is also possible the recone kit you have is a 2205 or some generic version of it . With a stated free air resonance 1/2 way between the 2225 & the 2235 ( 30 hz ), it may be creating decent enough VLF . This kit is no longer available . ( BTW ; The 2205H looked just like a 2225H ).

Recap > go with point "A" .

:)

ogmios
10-11-2005, 10:49 AM
Big Thanks Earl. I'll go with the 2235 recone. I hope it's still available somewhere as soon as I have some cash.

I will try to take a picture of it if you are interested. I just saw a pair of 2231A on ebay that had white cones?!?!? I'll get a pic of both tonight after work. I don't really have electric parameters other than resistance.

I guess it's possible they were both reconed. The original owner is in the family, so I know that he had jbl do it, if he had them worked on.

Unfortunately I can't ask as the poor guy's is in a vegitative state, and the previous owner who got them from this guy doesn't know anything about them, he keeps calling them "Fisher"s LOL.

ogmios
10-11-2005, 10:57 AM
I definitely don't want "higher" resonance. This baby is LOOOW and I definitely don't want to mess that up.

They must not be 2225 recones if the dust cap was solid.

Tom Loizeaux
10-11-2005, 08:00 PM
I agree that you should re-cone the 2231 with a 2235H cone. You'll love the sound and it will deliver what has made the 4343 a great speaker. Once the re-cone has broken in, compare it to your other 15. You will probably want to re-cone it with a 2235 cone at some point.
Other then carefully using "upgrades" for the 4343, its very difficult to change componants, or anything in the crossover, and get performance that equals, let alone exceeds, the original.
Get your 4343s restored and listen to them for a while.

Tom

speakerdave
10-11-2005, 08:33 PM
I just got a pair of 4343 given to me . . . . Thanks, wonderful site, been lurking a few months.
Welcome to the forum, and please stick around so some of that can rub off.

David

LE15-Thumper
10-11-2005, 09:05 PM
Yes... It is possible...

Replace your drivers having foam surrounds with a 1500FE, ME150HS, or 1500AL. None go as deep as the 2231 or 2235 but they don't rot as fast either. EQ is the best bet to fill in the very bottom end when using those drivers. The LE14H-3 is the only driver I can think of right now besides the W1500H that can go real deep. The W1500H is probably not a great replacement driver for the large format 4-ways... well, on second thought, it might actually work with a 2122 and a lower crossover frequency...

Where might a JBL'er find pics and specs on these new Consumer drivers ?
Lotsa info on the pro out there.
I hate to wake up Giskard again !!! I miss that cantankerous walking JBL encyclopeadia. ;)

Mr. Widget
10-11-2005, 10:34 PM
I believe they have all been posted here at one time or another.

http://audioheritage.org/vbulletin/showthread.php?t=6557&page=1&pp=15

http://www.harman-japan.co.jp/products/jbl_cons/1500al.htm

http://audioheritage.org/vbulletin/showthread.php?t=6006


This is what I could turn up without trying too hard.

Widget

4343mod
01-12-2006, 12:33 PM
Hey folks, well I finally did it. I have been dreaming about this since the JBL DSC280 speaker controller (x/o) came out in the mid 90's. The passive x/o's are sitting on a shelf in the other room, and the 4343's are now being driven by (2) Behringer Ultradrive DCX2496 digital active x/o's in mono into a Rane 100WPC 6 ch. amp and the existing Crown 800WPC 2 ch amp. When the DSC280 came out, it's street price was in the $4000 range with a 20/48 DSP engine. I got these 24/96 boxes which use the Analog Devices SHARK DSP for $260 each shipped. I finally put my telecom relay rack to good use! I just have to find a better place for my preamp.

The final word in inner detail and resolution is lost, but SO MANY other things are right, its a no brainer- the DCX's are pretty awesome. Being able to adjust every driver parameter with a laptop from the listening position is priceless, and more fun than I've had in a long, long time. The 2121's are singing better than ever.

Andrew Bacon

glen
01-13-2006, 01:05 AM
Sounds like a sweet setup.

What settings have you arrived at from your listening position tweaking?
Crossoer points?
slopes?
phase shifts?
time delay?

Give us the birds-eye low-down on this caper!

4343mod
01-13-2006, 12:46 PM
I just took 1/2 hour to put it all in, and when I hit the post button, it asked me to log in AGAIN and vB lost my post. This has happened before, and I forgot to copy my reply to clipboard BEFORE hitting the post button. Argh!

:bs:I'm going to go kick somebody.

PM me if you want to come over and hear it for yourself! :)

4313B
01-13-2006, 12:50 PM
One always has to remember to do a Ctrl-A followed by a Ctrl-C before hitting that post button!

glen
01-13-2006, 02:39 PM
... forgot to copy my reply to clipboard BEFORE hitting the post button. Argh!

Some times I'll actually compose my post in another program (notepad, or email) before dropping it in to the reply message body. This also allows me to bounce around on the internet without worrying about closing the "Reply to thread" window by accident.

4343mod
01-14-2006, 04:45 AM
Some times I'll actually compose my post in another program (notepad, or email) before dropping it in to the reply message body. This also allows me to bounce around on the internet without worrying about closing the "Reply to thread" window by accident.

Sorry for not getting back quicker, had a run in with the local constable. j/k
Instead of writing it all down again, I'll post a couple new pics. That one I posted is 7 weeks old, and since then I sold the Tascam CDR. My nephew and 2 nieces love the rig, but skoffed when I didn't download MP3 much less be able to play their lists, so this is as it stands TONIGHT. I hate mp3 still, but it sure is fun, and some of my "old school" faves I have on CD sound just as good, if not BETTER for "noise shaping" funk. Go fig! 1983 Anthrax DeathRider at the click of a button!

Anyway, I hesitate to add bunk posts that will be deleted, but pics are nice, no? Thanks Mods! ;)

4343mod
09-09-2008, 12:27 AM
Hey folks, I stopped by for some search advice on driver replacements for some L100's (LE25, LE5-2) and thought I'd check in on my pet thread.

It's been too long...
But since then...I got a TOUR OF THE JBL FACTORY and I stood IN and PLAYED in the ANECHOIC CHAMBER at the Balboa facility... I love my job.
Now I can die a vintage JBL lover and be content.
The poor guy who toured us stood up to comments like "Is your convention red black and black red nowadays?" and other smartassery. (no, it isnt)

It's nice to see the old thread again, the system has grown. Will upload newer pics to a server soon. Thanks for looking at this thread again! :)

Maron Horonzakz
09-09-2008, 08:55 AM
Use a flash this time!!!;)

herki the cat
05-11-2010, 04:20 AM
QUOTE=4343mod;86285]I just took 1/2 hour to put it all in, and when I hit the post button, it asked me to log in AGAIN and vB lost my post. This has happened before, I forget to copy my reply from the clipboard BEFORE hitting the post button. Argh! :bs: :)[/QUOTE]


herki:
I :dont-know: how it happens but when i am looking at the preview of a PM composition and i forget to step down away from preview changes to the text composition box to punch in the text changes ... unintenional "submit replys" do frequently occurr. Never happens in replying to a forum post. BTW, i had to learn to never forget to hit the "Save button" in closing a forum "Edit Post" event.

Maybe Don can fix the PM software to function like the forum reply system.:bouncy:

The solution i have now been using to prevent inadvertant" PM send" is to have my own "Usher ID" in the recpients button so i can retrieve my original text to finish up and then change the "recepient's User ID" ... works like a charm.