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DavidF
07-13-2003, 11:32 PM
Looking for some confirmation (or some enlightenment) from anyone who has some JBL LE5-family mids on the bench. I thought I had picked up on JBL standards on a few things, and felt I had a handle on the black-is-sometimes-positive issue. But now I am confused about drivers that use the quick-disconnect type terminals. I recently had a LE5-12 re-coned. When a gave it a brief test, I noticed that the positive terminal was different than all others I have on hand. At first, I thought this a goof but I realized this may be hard to actually do (reverse the terminal connections). Further browsing of stock JBL networks (Tech Sheets and some networks I have on hand) that use the various 5 inch mids with terminals (LE5-6,10,12, 104H, H-2 etc) I notice that anywhere the polarity is shown on the Tech Sheet, the solid-color positive-connect wire terminates in a male connector to match with the female terminal on the driver. The re-coned driver follows this convention and would therefore match-up to the polarity checks on the Tech Sheet networks. In all other models I have on hand, which I have no reason to they are not stock, I notice that the male terminal on the drivers is the positive terminal (positive connection from battery to male terminal on driver pushes cone outward).

Please, I am missing something here?

DavidF

4313B
07-14-2003, 06:08 AM
Positive voltage to female terminal on the transducer causes inward cone motion. The female terminal on the transducer is "red".

boputnam
07-14-2003, 09:22 AM
In all other models ... I notice that the male terminal on the drivers is the positive terminal (positive connection from battery to male terminal on driver pushes cone outward).

I may be confused by your post (and which is male/female you refer to...), but this quote / your report cannot be correct: Positive signal to positive terminal will make the cone move in. That is JBL convention, certainly for the vintage tranducers you are asking about. But your last sentence (the above quote) makes me think otherwise.

So, either you have mis-identified the gender, are holding the battery upside down, someone has futzed around with your cabinet wiring before you, or I simply don't get it! :bash:

At first read, I thought perhaps the LE5-12 recone kit had "updated" the polarity (as Giskard has pointed out happens to the 123A on recone). Of course, my use of "updated" is horribly insensitive on my part... :spchless:

Give us another report, maybe with pics of the posts, side-by-side? And (very importantly...) what cabinet and network are you working with? The 4312 L/R is positive (odd, but true, and it used the LE5-12) Just a guess.

Alternatively, ignore all this hoopla, and merely take a AA and connect the + to Positive terminal and see the cone action. That takes away all the doubt (and if you're going cabinet positive, begin the wire-cutting and re-soldering to swap gender on them dang "quick" terminals... :p )

Robh3606
07-14-2003, 08:47 PM
Well this will really mess with your head.

I have an original 123A not reconned and it is cone goes out with a positve voltage on the red terminal. Standard polarity.


104H-3 Positive voltage to the male is cone out like Rob says.

LE5-5 Same as 104H-3

2105H Positive Voltage on red terminal cone goes in JBL standard polarity.

Ain't this Fun:banghead:

Rob:smthsail:

DavidF
07-14-2003, 11:12 PM
OK, here is clarification of my issues… somewhat.

Assumed: Pro units (and spill-over into consumer) used Black to identify terminal where positive pulse would cause cone (diaphragm) to move outward. Assumed, again, that JBL would assign this with a positive (+) on schematics and would route a solid color wire to this terminal (black-striped of same color conversely assigned to Red negative (-) terminal. JBL’s bulletin reiterates this convention, a “Positive System” is that with positive pulse to red terminal resulting in outward motion. “Negative System” is that with positive pulse to Black (non-red) terminal resulting in outward motion. I am OK here.

Then I try to apply this to, for now, to two different systems and I begin to lose consistency in the process.

Consumer model L112:

System terminals Red for positive, Black for negative. OK, a concession to market convention in consumer products. Woofer 128H with Black positive terminal. Green wire feeds Black terminal as shown in the schematic below. This makes the system “positive” using a “negative” driver. Positive pulse to Red system terminal results in outward motion of woofer cone. With the Mid I begin to stray. The schematic shows White/Black wire feeding negative terminal with the signal from the circuit. OK, a common reverse connection for the bandpass circuit, or so I first thought. The female connector from the lead mates with the male connector on the driver, which is the “positive” terminal. Therefore, the signal feed from the crossover results in a “positive” connection with the Mid which is in phase with the woofer, contrary to what I thought by reading the schematic. So, I do not follow the schematic assigning the “-“ to the “positive” terminal of the LE5-12.

Pro model 4412A1

System terminal is Black for signal, Red for return. Solid green wire feeds signal to Black (positive) terminal of woofer under my assumed connection protocol. A “Negative” system feeds a “Negative” driver with the positive pulse resulting in outward motion on the woofer. However, the schematic below, as well as a factory circuit drawing I have, indicates that a positive pulse to the Red terminal will push the woofer cone outward. This means that the woofer is operating in a negative phase. Green wire to red terminal rather than Black (opposite my assumed convention)?

The schematic also shows the Mid to be a positive connection as with the woofer. This jives as the Black/White wire tapped to the Red system terminal feeds the male driver connector, or the “positive” terminal. This driver, also, is operating in a negative phase.

The schematic shows the tweeter with solid yellow wire feeding the positive terminal of the tweeter (confirmed that the 052 has two male terminals the smaller of which is the “Positive”). The yellow wire is tapped to the Red system return terminal (opposite my assumed convention) and this would follow the schematic indicating a “Positive” connection.

So, all three drivers are in phase with each other, but as a system, operating in negative phase. Really haven’t caught on to this quite yet.

I have one LE5-12 in very good shape save dimples in the dust cone that I thought I could match with a re-coned driver. That driver arrived back with a distinctly different surround (not glossy, or doped as the older surround appears) and, as mentioned, different polarity. A brown shoe in a black wardrobe.

It would seem JBL and Microsoft both suffer the bane of legacy in their products.

DavidF

DavidF
07-14-2003, 11:14 PM
Tech Sheet for L112 attached.

David F

4313B
07-15-2003, 06:06 AM
Hi Rob,

All three of your transducers are the same polarity. You applied positive voltage to the male terminal which is the "black" terminal so cone will move out. You applied positive voltage to the red terminal on the 2105 so the cone will move in. All the transducers in the photo are "traditional" JBL polarity. Apply positive voltage to the RED push button terminal or female terminal and the cone will move in.

I don't know about David's recent LE5-12 recone because I just reconed two LE5-12's and they are the same old "traditional" JBL polarity.

The LE5-6, LE5-8, LE5-10 and LE5-12 take the C8RLE510 kit and the 2105H, LE5H, LE5-3, LE5-5, LE5-9, and LE5-11 take the C8RLE59 kit. The polarity doesn't change between drivers.

4313B
07-15-2003, 07:58 AM
Applying positive voltage to the RED terminal of the loudspeaker system will yield the following:

128H cone will move in since positive voltage is going to the RED terminal on the transducer.

LE5-12 cone would move out since positive voltage is going to the male (BLACK) terminal on the transducer.

044 diaphragm would move in since positive voltage is going to the female (RED) terminal on the transducer.

This might be of interest to some. The 044 follows the same "traditional" "JBL polarity standard" of "positive voltage to female (RED) terminal causes inward cone/diaphragm motion". However, the male terminal has a (+) mark stamped into the aluminum frame. If you hook up positive voltage to the male terminal with the (+) stamp next to it you will get outward diaphragm motion. For those of you with L96/L112/L150A systems you may want to try reversing the polarity on your 044 transducers so they follow the 4313 phase convention. See if you prefer the sound. The reversal can be easily done at the point where the leads to the 044 connect to the PC Board. For those with 4313 systems, you may want to reverse the leads going to the 066 to see if you prefer the L96/L112/L150A phase.

Anyway... it's all fun and games until someone loses an eye, then it's just fun...

boputnam
07-15-2003, 08:00 AM
Assumed: Pro units (and spill-over into consumer) used Black to identify terminal where positive pulse would cause cone (diaphragm) to move outward.

DavidF: Thanks for taking the time to clarify your observations - very helpful. I am still reading - and re-reading - your post, but at first glance...

Your first premise is incorrect. The Red terminal on the transducers is the "positive" terminal. Positive voltage applied to the Red terminal will cause the cone to move inward (or "negative" to the industry standard). Swap your color expectations, and maybe things will be more sensical.

Bear-in-mind that it is common to cross phase transducers in the same cabinet of multi-way systems (i.e., two-, three-, four- or five-way). That is, in a three-way cabinet it is not uncommon that the engineers decided the LF and HF would be (say...) running "negative", and the MF would be out-of-phase with them and run "positive". Using the phase cancelling effects in areas of slope overlap between the transducers can improve imaging.

I'm going to just grab the schematics and try and decipher them for you...

OK got 'em now, and I agree with Giskard (to do otherwise, I might lose an eye... ;) ). Looking at the L112 schematic, be very aware that the network switches signal path, and uses colored wire for convenience at the transducer end, to wit:

L112
LF: the 128H is negative, and is RED INPUT to GRN to (+) Red terminal = running negative

MF: LE5-12 is negative, and is WHT to Red terminal, HOWEVER the positive signal is pathing from the RED INPUT to the WHT/BLK lead to the (-) Negative terminal = running positive. Look carefully at the schematic and you will see what I mean.

HF: 044 is negative, and RED INPUT paths to YEL to (+) Positive terminal = running negative.

In my self-accused parlance, I refer to this as a "negative" cabinet - referring to the how the LF is running.

4412
Interesting - doing the same exercise, you can see the 128H here is running Positive (RED INPUT paths to GRN/BLK lead to Negative terminal). So, the 4412 cabinet is running "positive", just like it's predecessor the 4312 L/R which I have a pair of, and got me into this mess to begin with!

Time for the good ol' warning: If you're paring the 4412 cabinet most other JBL cabinets, you may have phasing issues.

:banghead:

DavidF
07-15-2003, 09:29 PM
OK guys, one more shot and maybe I will shut up. Rather than try to overthink this matter, which is my problem to date, maybe I can shoot this comment out for rebutts. I now think my problem is not recognizing the use by JBL of negative phase as the "norm". I am assuming that since the Black terminal is, in negative mode, is the "positive" terminal which typically accepts the signal leg of the circuit. What I interpret from your responses (thank you by the way) is that signal path follows with red as hot, black as ground/return. JBL, in normal configurations, feeds the signal through the red terminal. As such a positive pulse will cause the driver to move inward. Therefore, all drivers operate in negative phase (the drum kicks, the woofer sucks, si?) The exception would be operating in positive phase for crossover summation effects or phase correction.

Am I getting warmer?

DavidF

4313B
07-16-2003, 06:41 AM
Don has a response here that relates to this thread as well.

http://www.audioheritage.org/vbulletin/showthread.php?threadid=477

"Therefore, all drivers operate in negative phase (the drum kicks, the woofer sucks, si?)"

Yes. In multi-way systems the phase of the transducers is adjusted accordingly by simply reversing polarity. From Don's post, JBL transducers were designed so that positive voltage to the RED or + terminal resulted in a rarefaction. If you want your older JBL's to match current standards simply switch the polarity on all the transducers. Bo and others have talked about having to do this when mixing JBL systems with other systems.

martinleewin
07-16-2003, 02:12 PM
If JBL (and I suspect all Lansing products) from the vintage in question are phased to each other corectly, but "opposite" to the otherwise conventional and/or modern world... why should we go to the trouble of reversing all the wires inside the cabinet???
When it would be so much easier to stick a label on the cabinet termination indicating "Opposite of Conventional Polarity" and keep the vintage unit in 'stock' configuration to boot?
Understood; that combining multiple multidriver cabinets with some drivers employing switched phase will cause inter-cabinet cancellations and image-shifting if they are close enough to each other. Those who switch back such out of phase drivers for intercab compatibility should also note this change on the cab termination panel so that others will understand (and as a reminder to themselves) what the heck is going on.
I would inquire as to whether it is the voice coil termination or the magnet (or both) polarities which is "opposed" to the popular/modern convention just as a trivia question-- in case I am on Jeopardy and one of those answers come up under the category of "Unconventional Geniuses".
Notice how I avoided the words "positive" and "negative" so far in this message. The words are confusing, and thus counterproductive, if they mean different things to different people. Neither is there "right" nor "wrong". Only what works for them; and then what works best in a larger group situation. I hate to be politically correct-- it just worked out that way for this topic.
To make things worse!!! The electrical polarity conventions are "WRONG". . . at least if you ask a physicist-- who swears that ELECTRONS HAVE A "NEGATIVE" CHARGE... and your battery's (+) terminal is from where the electrons flow (on that last part we have agreed).
That is why I only tell customers things make them go "BATTERY(+) = OUT" {as the basic goal} and how to make that happen in the least problematic and most harmonious way. Then mark wires with a black pen accordingly.
Anything different {from historical or acoustic design origins} is "opposite" to the majority convention. LABEL it as "OPPOSITE" because it may not work best in combinations. Now feel free to experiment for what sounds best to your ear or test apparatus. I might end buying pieces of your customized array and should not have to trust your memory. All I ask is that you DOCUMENT your results for future clarity.
The only exception being dual series-facing subwoofers phased opposite to each other; then in or out becomes up or down?... east or west? I give up... how many subs do you really need, anyway?
Martin W.

boputnam
07-16-2003, 02:59 PM
...that combining multiple multidriver cabinets with some drivers (and cabinets) employing switched phase will cause inter-cabinet cancellations and image-shifting if they are close enough to each other. Those who switch ... such out of phase drivers for intercab compatibility should also note this change on the cab termination panel so that others will understand (and as a reminder to themselves) what the heck is going on.

That's what I'm talking about ;)

The rest has my head :spin:

boputnam
07-16-2003, 03:32 PM
The only exception being dual series-facing subwoofers phased opposite to each other; then in or out becomes up or down?... east or west? I give up... how many subs do you really need, anyway?

Hilarious! :rotfl:

martinleewin
07-16-2003, 10:48 PM
Well, Bo,
I didn't think I had to add AND CABINETS to "...some drivers employing switched phase will cause inter-cabinet cancellations..." because that is really a Duh! that everyone should know if they can pronounce the word "faze" in passing. Whole cabinet phazing is readily accomplished with the AA when you can see the cones move. A compression driver out of phase, especially one behind a lens, is a dirty lowdown sneaky trick by comparison. Because if, say a mid horn in 1 of 3 opposite phase, sounds good with that cab, a fully in phase parallel cab right next to it will shunt the overlapping mids in an undesireable east-west fashion.
I would expect Microsoft to design that "feature" into computer monitors they sell to specifically interfere with competitive side-by-side comparisons. But I'll bet all Bill's home speakers ARE ALL in the same phase.
Sure, it WOOD be nice if the manufacturer put a correct schematic on the termination panel. But they will just say "you should not buy any other company's speakers but ours" and slap a "no user serviceable parts inside" sticker on the front (if that is the access point) if too many users complained. Product liability risk issue solved. Hey, they put red AND black terminals on the panel... what more would you want? Did you read the manual? It tells you all you NEED TO KNOW to install THEIR speakers in YOUR home, doesn't it?
We who know better should not be guilty of the same disregard for proper labelling. We don't even have a 976-WHOCARES? hotline to handle the complaints.
What REALLY fazes me out is that I can't get my Mac with Internet Explorer and VB to get these silly smilies to work!
Martin W.
Wizard Labs

boputnam
07-17-2003, 07:53 AM
Whole cabinet phazing is readily accomplished with the AA when you can see the cones move.
I've had difficulty with that, particularly for the MF and HF - seems that much of the energy of the AA get's consumed by the network and makes the results less visible.

I've had great luck with the "Cricket" of Galaxy Audio (http://www.galaxyaudio.com/galaxy/Products4.html#TEST EQUIP), thanks to a non-related-party recommendation from Mike Caldwell (http://www.vintageaudiosales.com/). Results are clear and unambiguous.

Mr. Widget
07-17-2003, 10:04 AM
" I've had difficulty with that, particularly for the MF and HF - seems that much of the energy of the AA get's consumed by the network and makes the results less visible. "

Since most systems employ crossovers to filter out the low frequencies from the mid and high frequency drivers the very, very, very low frequency of 0Hz coming out of a battery better be filtered out!

boputnam
07-17-2003, 10:11 AM
the very, very, very low frequency of 0Hz coming out of a battery better be filtered out!
That'd be it! :rotfl:

4313B
07-17-2003, 10:11 AM
"the very, very, very low frequency of 0Hz"

Some days I just skip reading the funny papers and read this forum instead :p :p :p

Thanks Mr. Widget :)

martinleewin
07-17-2003, 11:54 AM
RG; Glad we can be of amusement to you.
BP & Mr. W.; EXACTLY my point... you may have to bust inside or rummage thru a tech lib to figure these things out for yourselves if you are not sure all drivers in a cab are mutually phased. So then YOU know. But will you remember? Scribble or print the schematic and tack it to the back of the cabinet. Staple an envelope flap, thumbtack a sketch or scribble in crayons as you choose.
Now you will always have that ref info when and where you need it. The next owner/user will also appreciated your forethought to save them from the tedious repetition of your research.
Sometimes I upgrade a commercial speaker cabinet for resale with better drivers, alter the crossover specs, and other stuff. I print a new Wizard Labs spec label, laminate and staple it to the back of the cab so customers know what they are getting and what to do with it. Doing so helps the customer get the hookup right the first time and saves tech support calls to my "factory".
Martin W.
Wizard Labs

Doctor_Electron
07-18-2003, 05:40 AM
NOTICE:
This is a Dr_Electron-length post.
Several years ago, I undertook a project to re-wire my pair of 4410's, since the crossovers looked like low-rent rats' nests, and I do not trust sonically anything less than soldered connections inside the cabinets.
Unfortunately, I got in a hurry and did not thouroughly document the wiring during the demolition phase of the project, or save the cheesy original wires.
When ready to put it all back together, I requested and received the tech specs PDF for the 4410L,R from JBL Pro customer service @ Northridge, and immediately noticed a couple of odd things about the wiring diagram (in view of my several previous & successful, pain-free speaker re-wires, & experience working on JBL, etc. components going back to the early 1970's).
First was the apparent anomaly of the 127H woofer & 104H-2 being shown connected "in-phase"; with second-order butterworth networks the mid is normally connected 180 degrees out from the woofer. I again contacted JBL, and was "assured" that they "did things differently on different types of systems".
So I went with their #^!^&*%* advice.
Anomaly # 2 was the interconnection of the mid and high drivers' L-Pads "low" terminals, with no connection to "signal common". Again contacting JBL, I was told that the controls were meant to be "interactive", and that the drawing was correct. However, I distinctly recalled that the mid and high output levels as originally wired could be completely turned off (as in every other of the numerous JBL's I had owned). The "interactive" topology did not allow this, and IMO also caused an unaccectable vagueness in tonal balance no matter the %&*&*!# "interactive" settings.
I wound up connecting the L-Pads' common junction to "signal common", and judged the result to be satisfactory (& typical).
Now, back to the phasing questions: With the 127H & 104H-2 drivers connected in-phase, the sound was so horrendous that over a period of time I thought that my CD player, and/or power amp had gone south.
I recall discussing that can of worms with Robh on the phone at the time. He was addressing issues of trimming the values of the fixed padding resistors in some newly acquired JBL's, which were essentiall identical to the 4410's, save port locations, cabinet geometries, and use of fixed pads. As I recall, we weren't able to help each other much at the time on either set of issues.
After much suffering hearing very sick sound, experimenting, documenting & re-documenting every change, as well as trying repeated CD & amp swapping, I satisfactorily addressed the phasing quandary by rigging up a phase-reversal switch with leads long enough to reach the typical listening position, fed the mid and later the high driver through the switch (wiring routed out through the port(s), and finally resolved the problem(s) through listening evaluation. The results were profound and pleasing.
Final verdict: 127H & 035tiA are connected in-phase; the 104H-2 connected out-of-phase.
HOW ABOUT THEM APPLES?
Of course, now I start a notebook for any project (duh, learned that back in '75 on an R&D job supporting engineers, but got lazy & complacent with experience), and document EVERYTHING!
NOTE: Any such audible phase testing must be done from the listening position, as the sound waves are going through normal 360 degree (peak, null [180 d.], peak) wave propagation as they travel from the baffle to the listener. Evaluating / adjusting driver phase at closer distances does not give a real-world sonic result.

boputnam
07-18-2003, 06:55 AM
Doctor_Electron

Thanks for that.

I have found that many (but not all...) three-way systems are phased with the MF out-of-phase from the LF and HF. Certainly so for the 4312 L/R, but the 4313B has both the MF and HF phased together, and out-of-phase with the LF. So, it all depends, and in the end, it's how it sounds that matters.

The reason I have devoted so much time to this issue, is that building my own cabinets with seemingly "ideal" compliment of transducers was yielding wobbly results - which I came to discover were polarity and phasing related.


I satisfactorily addressed the phasing quandary by rigging up a phase-reversal switch with leads long enough to reach the typical listening position... THAT has me ROFL - what a clever idea. It is so hard to A/B systems meaningfully - this sounds patentable!

;)

4313B
07-18-2003, 06:59 AM
The phase reversal switch is documented in the JBL Loudspeaker Instruction Manual dating back to the 70's.

The phase also depends on where the loudspeaker will be located with respect to the listener. Up front in your face or across the room.

*****

It is interesting to note though that the L80t/L80t3, which is the Home version of the 4410, has all the drivers in phase as well. No wonder that whole series sounded goofy. Dr. Electron has solved the mystery :) Actually, I did have a discussion with G.T. about that many years ago and there WAS a reason but I can't remember the specifics now, I really didn't care then and I guess the information didn't "take".

martinleewin
07-18-2003, 10:09 PM
Dr. Electron (great name!) shirley illustrated my point of documenting the before so that the during is simpler to accomplish for a satisfactory after.

You indicated an opposite phased midrange driver is common in JBL systems. I have not found this to be the case with the (non-JBL) mostly-cone (some piezo tweeter) transducer systems I am more familiar with. Is this because of the the fact that JBL used midrange compression drivers more often than most manufacturers in their speaker systems?

I know that compression vs. cone transducers are significantly faster on transient response. And that pure conehead designers may set their cone transducers rearward as the cone depth shortens in order to align the effective driver propogation planes with respect to equal time domain starting points. A compression driver with horn already accomplishes this (perhaps too much?) by positioning the midrange well to the rear of the cabinet face.

Many designers use an intermediary smaller cone midrange to bridge the time domain gap between the sluggish woofer and the much quicker (and often more forward) tweeter. IMO 2-way systems rarely sound "in phase" through the critical midrange because of the comparative difference in driver speed no matter how good the frequency response is.

Is there something about compression/horn transducers which prompt the designer to set them in opposite phase-- vs. simply mechanically positioning them to an equal planar source position?

And since I know far less about compression driver theory and construction... can the forum members provide links describing compression driver;
operating principles
acoustic properties
construction details (material properties, cross section or cutaway dwg)
care and feeding...
so I could better understand their behavior?

I think this topic was worth visiting again for the knowledge gained.
Martin W.
Wizard Labs

DavidF
07-18-2003, 11:18 PM
Watch them Nulls! I can only think of two influences that may cause a horn to act differently than a cone relating to the crossover design. One is the longer path of the source (group delay) and the other the directivity of the sound wave (power response). The reversal of adjacent drivers is more to do with the summation of the response in the area of the crossover and even this effect is limited to certain crossover design models. For instance, a three-way system on a second order Butterworth may cause a huge null at the crossover frequencies. Reversing the phase of the mid reverses the influence of phase cancellation and provides a smoother frequency response. In any event, the reversed-phase mid is by no means universal for all applications. You have to convince me (I am easy to convince) that horn compression drivers are more (or less) responsive than cones in terms of transients. Would it be more appropriate to state that for a given sound pressure level the driver/horn is using far less energy and effort at a significantly reduced distortion level? A cone has the potential to deliver all the bite and sparkle of a horn. Given that, the driver/horn system has the headroom to sustain accurate dynamics at SPL levels that cones can not match. The remaining differences are probably open to endless debate.

David F

martinleewin
07-19-2003, 11:05 AM
DavidF, Thanx for the clarification on the midrange opposite phasing being needed to address the crossover phase shift response.

re; "You have to convince me (I am easy to convince) that horn compression drivers are more (or less) responsive than cones in terms of transients. Would it be more appropriate to state that for a given sound pressure level the driver/horn is using far less energy and effort at a significantly reduced distortion level? A cone has the potential to deliver all the bite and sparkle of a horn."

I am not in a position to convince by means of test data. My opinion was based on some limited listening test examples. Perhaps when I get some realtime analysis software to run pulses with high enough data acquisition rates to evaluate some example drivers I would be able to quantify and substantiate that widely held belief.
Your statement " Given that, the driver/horn system has the headroom to sustain accurate dynamics at SPL levels that cones can not match." does support my premise at the loud end of the amplitude range, doesn't it?

Martin W.

DavidF
07-19-2003, 09:28 PM
Martin,

Your statement " Given that, the driver/horn system has the headroom to sustain accurate dynamics at SPL levels that cones can not match." does support my premise at the loud end of the amplitude range, doesn't it?

Yes, and then again, no. Think this through for a minute. Take a Klipsch woofer in reflex cabinet compared to installed on a folded horn. I would expect the transient characteristics to be the same, save around the resonance frequency. However, for the same sound levels, the horn loading is going to significantly reduce the excursion requirements. Now if we push a baffle-mounted cone driver to the point where its breakup causes audible distortion and compression effects all the while the horn-loaded driver, at the same SPL, will be operating at much lower distortion levels. Therefore, the horn-loaded driver may seem to be displaying better transient characteristics. This is not due to better transient characteristics but rather cleaner and more accurate output through the horn mouth. In my modest space, I would not be able to tolerate testing this upper limit “horn benefit” to test the theory. Now if you start off on focused wave propagation mathematical models, you will quickly leave me behind.

What do you think?
David F

martinleewin
07-20-2003, 11:07 AM
Now, David, you are bringing up particular design elements and extreme usage which will distort a typical listening picture.
1. A Klipsch-type speaker, with its long folded wave path, introduces substantial delay for the reflex loaded driver(s). This is another design characteristic with its own pros and cons best left for another discussion. Not that that will stop me, though.
re: "Take a Klipsch woofer in reflex cabinet compared to installed on a folded horn." I accept your generous offer to take it off your hands. How about if we split the shipping charges?
"I would expect the transient characteristics to be the same, save around the resonance frequency."
Measured at the driver--perhaps, but no data presented as support. Not having any real design knowledge or measurement data, I must surmise your point is based on the cabinet's air pressure load within the resonant band will inhibit the driver's transient ability. Measured at the listening point--add aroundabout 10 mS delay for a folded horn design. A systematic complication of another sort. Now you need to employ Boseian engineering calculations. I (personally) find this design to be great for increasing driver "space" and low end response while causing multitudes of phase errors within the cabinet's range when not all the drivers are similarly delayed. My ear is particularly sensitive to phase errors induced by artificially extended wavepaths mixed with direct paths. My ear will "buy into it" at longer wavelengths and then objects to the mix when it approaches the midband and above.
"However, for the same sound levels, the horn loading is going to significantly reduce the excursion requirements."
Absolutely. Horn-loading EITHER type driver increases efficiency by decreasing excursion requirements WITHIN the effective HORN BW.
2. Basing an evaluation upon results obtained at maximum safe operating limits is neither prudent nor a fair representation of a speaker system's typical usage and best acoustic performance. I can not afford to damage that many voice coils to test a theory. Something I feel is best left to "pro" audio designers and road concert "sound" engineers to determine the maximum SPL vs. distortion so close to the end of life point. Would anyone care to donate some specimens for evaluation? You can have them back when we're done.
Where were we? Oh, yeah...
Transient response is often a secondary design consideration compared to efficiency and spectral compensation. Good transients alone do not guarantee "good sound". But better-appreciated designs will exhibit TRANSIENT characteristics at least equal to their FREQUENCY response characteristics. Then getting multidriver systems to work together (in or out of PHASE as a whatever works option) and then getting the DELAY times to coincide in a cohesive fashion... and you've got the perfect? Compromise.
I don't blame speaker designers for their limitations. I blame Newton and his darned First Law of Motion. It has, so far, kept anyone from designing the perfect flat, fast, and (inherently) in-phase single driver capable of full audio bandwidth.
I suppose that is why guitarists can be so much happier with their speakers-- a la a D130 or Celestion Greenback vs. all the rest. That is because we only care about three or four octaves; which is more than the chords some players know. + we expect DISTORTION and often demand more! Count me as a Celestion fan because their distortion is available in greater amounts and varieties (though SWR had to order a "special" [clean] version for their acoustic guitar amps) as catalog items. Stick 'em in a box with five or six sides, plug into your amp of choice, and play! It ain't no big deal. Want it louder? Just add more speakers and boxes and amps. If the sound sucks, it is probably not the speaker's fault.
Clean and full range speakers are for keyboardists and PA guys to worry about. Home audio enthusiasts, and especially Audiophiles, suffer from the same afflictions when they fail to achieve sonic Nirvana.
Martin W.
Wizard Labs

martinleewin
07-20-2003, 03:23 PM
Well, if you're going to go by the INSTRUCTIONS (to find whatever works)... should that be a bass or tenor male vocalist?

As far as "Utilize the phase condition which yields the most natural reproduction."... I thought this board was G-rated! Did Jim Lansing study at the same school as Masters & Johnson and Dr. Ruth? Sorry, I misread "condition" as "position". Never mind.
They call me Mellow Yellow,
Martin