My "New" 4345 Clones

[BMWCCA]

I can't thank any of you enough for helping me follow up on this. In the post Rob linked to above it would seem that losing the 20-ohm resistor is correct for either 8-ohm L-pad or 8-ohm drivers, at least that's the most sense I can make out of that thread. The 2425J is certainly labeled as 16-ohm but if there's one thing I've learned from this site about vintage JBL drivers, the ohm rating is one fast and loose data point. So, should I check DCR on the driver? The L-pads? Or just run a 20-ohm resistor across the HF output on the crossovers and see how it sounds? Seems like someone must have done it for a reason and "4313B" seems to be the source of the suggestion. I'm sure he has a reason for not commenting in this thread but I did brush this morning and used mouthwash. Honest!

I've checked and traced everything with respect to components on the crossovers and other than this anomaly, everything seems to be correct. I'll just leave the crossovers outside the cabinets until I'm either satisfied with them, or get tired of messing with them.

[Robh3606]

The 2425J is certainly labeled as 16-ohm but if there's one thing I've learned from this site about vintage JBL drivers, the ohm rating is one fast and loose data point.

Not for them it's not. There are both 8 and 16ohm diaphrams available. Forgeting what's on the label you could just as easilly have 8 installed in the drivers. If they measure about 4 ohms you have 8's in them which is why there is no resistor.

Rob

[Mr. Widget]

I'm sure he has a reason for not commenting in this thread but I did brush this morning and used mouthwash. Honest!

I believe he is currently on vacation... or at least taking a forum vacation.


Widget

[BMWCCA]

I believe he is currently on vacation... or at least taking a forum vacation.

Thanks. I'm reasonably certain I'll need a vacation, too, after I get done with this installation! Or maybe I should send my wife and kids on one right now before I start.

There are both 8 and 16ohm diaphrams available. Forgeting what's on the label you could just as easily have 8 installed in the drivers. If they measure about 4 ohms you have 8's in them which is why there is no resistor.

Thanks! Very helpful. I'll check it out as soon as they come inside.

But I did have another thought: The schematic shows the 20-ohm resistor AFTER the L-pad (at least that's what it looks like to me). I suppose it's possible that there's a resistor inside the cabinet since my boxes had outboard crossovers but the L-pads are mounted conventionally on the baffle. That might vindicate the crossover construction if I'm looking at this correctly. Right? Wait a minute; let me check NewHorizon's photo album . . .
What's that little black object on the HF L-pad output in the detail from NewZenith's photo album???

[subwoof]

In one of the earlier posts the TRS issue came up with the ashleys and the improbable use of *both* bal and unbal 1/4 jacks.

The ashley, like soundcraft and so many other manufacturers use an *impedance* balanced output where the signal is on pin 2 ( or 3 ) / tip and since it is driven by the last opamp, is actually 50 to 100 ohms Z.

All that is needed is to put the same value fixed resistor to ground for the other "pin" and the receiving load sees a "balanced" line.

Now this STILL has the potential for ground noise, and the CMRR isn't too great but it allows a lot of feild patching that works without the worry of shorting one side to ground and harming the chip(s).

So just use 1/4 to 1/4 plugs to the 400/200 and observe correct grounding methods and you should be fine.

As for the mystery 20 ohm resistor, OPEN your driver and look at the color on the + terminal. Green is 8, red is 16. The stock 43XX cabs use 16. The picture does look like the little black resistor is there - that's where I would wire it.

sub

[BMWCCA]

So just use 1/4 to 1/4 plugs to the 400/200 and observe correct grounding methods and you should be fine.

As for the mystery 20 ohm resistor, OPEN your driver and look at the color on the + terminal. Green is 8, red is 16. The stock 43XX cabs use 16. The picture does look like the little black resistor is there - that's where I would wire it.

Thanks! Again.
The pics show a red terminal.

The Ashly should show up Wednesday. I've got a bunch of 1/4" TS instrument cords of good quality. Fred Sanford has even offered his tub if I need more. I appreciate the help and that's the way I'm going to hook it up. But I did find it interesting that the newest Ashly XRhyphen1001 talks about:

• Active Balanced Inputs
• Servo-Balanced Outputs
The outputs are low impedance (100 ohms typical) servo-balanced using either connector. A servo-balanced output stage simulates a true transformer output to allow interfacing with virtually any type of load.

Whatever that means.

[subwoof]

Even if you used TRS interconnects it would still work. The crown input jacks ignore it and the ashley doesn't even put a signal on it. Save the $$ and use good quality 1/4 to 1/4 patch cords.

Don't listen to the "oxygen free, directional interconnect" crowd. Their agenda is to make you buy super expensive cables that have dubious claims.


Besides what happens when you open the bag? right..the damn O2 gets in and ruins them. And the only AC / DC direction issues is when you walk into THAT bar by mistake.

The old ashley "servo" balanced is exactly what I described. Now if it is true servo active balanced, the output stage would be much more expensive to make and there would be signal on both pins 2 and 3. The REAL pro stuff is made this way since they could be running a cable that is 1000 ft+.

Since those outputs are full active, you can use *either* pin with reference to ground for an unbalanced output and if you want to be sneaky, run pin 2 to channel 1 and pin 3 to channel 2 of any amplifier and you have just put it into bridge mode...

Isn't electronics fun!

[BMWCCA]

As for the mystery 20 ohm resistor, OPEN your driver and look at the color on the + terminal. Green is 8, red is 16. The stock 43XX cabs use 16.

I may have misunderstood. Did you mean open the 2425J and check the color on the diaphragm + terminal? Obviously I replied that the input terminal on the driver housing was red. Then I realized I'd never seen a green one . . .

[subwoof]

the color of paint in question is between the screw terminals on the + lead of the diaphram. There are pix on this site of this. I find it hard to believe previous owners installed 8's. These *are* clones.

sub

[BMWCCA]

the color of paint in question is between the screw terminals on the + lead of the diaphram. There are pix on this site of this. I find it hard to believe previous owners installed 8's. These *are* clones.

Thanks for setting me straight, once more. I was told they have the D16R2425's in them. I think I'll leave that check for after I've lived with them as-is for a while. Not that I know anything about it after 27 years of marriage to the same woman, but I think I remember Dr. Phil, or Oprah—or maybe it was Judge Judy—say that part of starting a new relationship is establishing a mutual trust. I'll go under the assumption everything is as was stated and hopefully have little sorting to do to hear these in their best form possible.

Couldn't find a link to a picture of a diaphragm terminal color code on LF, but I can see a little green paint here:

FedEx tracking says they had some problems with freezing fog at their Memphis hub on Friday. I think the Ashly's on a truck, creeping it's way east.

[Mr. Widget]

I have twelve pairs of 3145 networks to build right now (various driver specs as well as 4343 versus 4344 and 4345 enclosures to make it nice and hard) as well as six pairs of 3155 networks so I am a bit busy. This past weekend was spent doing a rush job for an expo in Japan.

Doesn't sound much like a vacation...


Widget

[BMWCCA]

I never liked that version and canned it years ago after the 4355 equivalent cc network slaughtered it. I thought that was common knowledge. I have a new version that I am currently tweaking with various driver sets (2121 versus 2122 versus 2123 and 2421A/2425H versus 2421B/2425J) using LEAP.
I simply wasn't following this thread. I have twelve pairs of 3145 networks to build right now (various driver specs to make it nice and hard) as well as six pairs of 3155 networks so I am a bit busy.

Thanks for your comments. Actually, I never found any thread in which this version was disparaged or superseded. I'd appreciate a link to a better version. I was unable to find that common knowledge during hours of what I thought was fairly exhaustive searching on this site. I've tried to cover any reference available through site search or Google and don't recall anything more current than this 3145 CC version.

Searching now using "3155" I see you built a CC version for Rick about two years ago, but I can't seem to find a schematic. I see it mentioned in other threads, but no links. I even found one of your posts from 12/07 talking about all the networks you were completing/shipping, including one biased 4345, though I don't find much discussion. Then I found a thread from a year-and-a-half ago where Rick seems to be offering the networks in various configurations. So is the "new" version available in schematic like the old "canned" one that got "slaughtered" by the new one, or does one order such a piece through you, or Rick? Nice foilcal in that thread, by the way!

Thanks again for any and all help, guidance, and/or clarification—past, present, and future!

[BMWCCA]

I'm sure! Unfortunately it isn't available yet. These networks really aren't meant to be plagarised by just anyone at this point in time. I find it pretty irritating that you got stuck with an original version.

Plagiarized seems a harsh a harsh description. I appreciate your concern, but from the threads on this site, it would seem the networks I have were the bee's-knees in design here at the time they were built from schematics you freely posted on this forum a few years ago. I don't really see how either of the past owners could have sold them to me with anything else if nothing newer existed. If there's no new application currently available, please just let me know when it might be and in what form and we can discuss how to get my 4345's updated, whenever.

Surely Dave wasn't the only one to build these networks from the schematic posted here, and they were always credited as what they were from the beginning of NewZenith's ownership-bliss thread. It's hard for me to tell how they were described in NoRealTalent's for-sale thread prior to that because no trace of it remains.

I'm not here for the human drama, angst, or arguments. I'm here for the enjoyment of music, JBLs, and the camaraderie. If I wanted petty disputation, I already have a wife and three kids! I've always been impressed with how freely everyone shared information and supported each other on LH. Now all of a sudden I seem to have become slightly mired in a bit of innuendo and obfuscation—for whatever reason.

So, let me ask this as objectively and innocuously as I can: What can I do to make these 4345s as up-to-date as possible? And how can I get people to be honest with me about them? I'm really a bit confused by the silly turn this whole odyssey has taken. Hopefully we can manage to get past it and look back on the entire history of these beautiful 4345's to this point as a humorous diversion out of the past.

Thanks again! I can't wait to hear them sing.

[Ian Mackenzie]

Not to open old wounds, but if I'm not mistaken, David Brink was previously known here as NoRealTalent and was the original owner of these Riessen reproductions cabinets. I'm told he built the networks using the schematic created by Giskard and Greg Timbers. You might also remember ex-member Steve Gonzalez once referring to Dave as, "my best Friend on the planet and fellow JBL nut".

I'm not privy to the inner working of this site or anything about the "recent unpleasantness" but I do know that as recently as two-weeks ago I was able to find both Steve Gonzales and NoRealTalent in the member section here in order to search for their posts from their profiles. Today they are only listed as "guests", if you are able to find a post attributed to either. Both ex-LH-members are on AK and you can see one of the versions of the networks (and the 4345s in the background) in this thread there: http://www.audiokarma.org/forums/sho....php?p=1494601

During the ownership of the last two members, there were component swaps a-plenty, as mentioned on LH and elsewhere. What I have right now are essentially a stock pair of 4345 with respect to the components. Without stooping to repeating rumor and innuendo, or breaking any confidence, I believe the first owner was unhappy in some way with the finish of the cabs (I, on the other hand, am quite pleased with it), and passed them to the second owner who swapped them back and forth with the first owner—as well as some components—until deciding to sell them in preparation for selling the house they were in and possibly returning to school. I have no reason to believe there's anything more to it than that—or possibly the love of the chase. Search for "4345 Bliss" and you'll see that at least the last owner was happy with them as recently as a year ago!

FWIW, the networks that came with the 4345s I bought are these:



Thanks for the offer. Nice to see SMAART is now available for the Mac OS (not that I could afford it). Is a "GEQ" something special in an EQ (excuse my stupidity; I'm trying to learn)? Or will a Soundcraftsmen Pro-EQ-44 third-octave unit work?

I recall this saga from years gone by. The problem was the builder had great difficulty reading a schematic and being ousted by the Pope he had troubles obtaining information on things like what is a tapped "choke"?

If it is the 2nd equivalent version as I recall the L Dcr values are so sensitive to proper operation it was not user friendly to build.

The 1st equivalent (Gregs & Giskards) was a charm to build and was quite tolerant in terms of L Dcr.

An 8 ohm compression driver will work but makes L pad adjustment a PITA.

The accuracy of the voltage drive curves (dips and peaking) moves around a bit depending on the L Pad position but there is so much slack in those Pads they need dialling in with a Db meter and sine.

Everyone who sells these seems to regret it if the new owner gets a handle on setting them up properly!

[BMWCCA]

I recall this saga from years gone by. The problem was the builder had great difficulty reading a schematic and being ousted by the Pope he had troubles obtaining information on things like what is a tapped "choke"?

If it is the 2nd equivalent version as I recall the L Dcr values are so sensitive to proper operation it was not user friendly to build.

The 1st equivalent (Gregs & Giskards) was a charm to build and was quite tolerant in terms of L Dcr.

An 8 ohm compression driver will work but makes L pad adjustment a PITA.

The accuracy of the voltage drive curves (dips and peaking) moves around a bit depending on the L Pad position but there is so much slack in those Pads they need dialling in with a Db meter and sine.

Everyone who sells these seems to regret it if the new owner gets a handle on setting them up properly!

Thanks Ian,

I believe we've resolved the 16-ohm driver question. Short of removing the diaphragm to check, 16-ohm is confirmed by the listing of the D16R2425 and the proper resistor on the L-pad. I'm not familiar with the first vs. second version of the crossovers but these follow the schematic of the version posted in the 4345 Reference thread. What can I say? I wasn't there at the creation. I'll check the setup with as much instrumentation as I can muster but I must say I'm intrigued (and comforted) by the suggestion of setting them up using the L7 A-B methodology!

I don't know a "tapped choke" from an artichoke, or "voltage drive" from "iDrive" but I do appreciate helpful suggestions over dredging up past unpleasantries. I don't have any hidden agenda, much less any knowledge of these systems to share. I'm just trying to get the most out of them so I can enjoy the music. I will share what I can. I don't need to buy a Mensa card to know I can understand a new concept if given a chance and a good teacher. I've shared the expertise I do have with thousands over the years, hopefully without making them feel badly about their ignorance on the topic.

I'm not interested in continuing a saga, though history does intrigue me and may answer some questions. I just want to hear the music! Thanks for any help you can offer to get these inanimate objects functioning at their best-possible level. I really do appreciate it.