Need help to understand power requirements for 4355 and use of external crossovers

[markustubesnow]

So. There's a refurbished JBL M552 crossover on the 'bay for over ~$400

Might one of the new, current production crossovers, like the JBL 223XS, the 234S or 234XS work? They're cheaper than the M552, just sayin'. Might they fill the bill? Or is there something about them that renders them less desireable?

Thanks all. Superb bit of work here...

[markustubesnow]

Replacing the wiring is the easiest thing you can do, upgrading the caps is probably the next easiest thing you can do, but let's step back and put things in order of importance.

Driver status:

The woofers. Are they still 2235H woofers with original cones and mass rings? Have they they had new surrounds put on them or aftermarket kits?

The 2202H, these are very likely fine, as long as there is no sign of visible damage. These speakers have long lasting cloth surrounds and long lasting ferrite magnets.

The 2441 drivers. Likely 50/50 that they will need a rebuild. Original diaphragms are hard to come by, there are the Truextent diagrams at a premium cost and performance change.

The 2405H drivers. Likely damaged or out of spec. Impossible to repair at present. The only solution is to look for suitable replacements with verified performance.

The Networks:

Best option is to pull the originals and keep for collectors value.
Replace with charge coupled networks.

Clean/replace the L-Pads.
Clean/replace the input terminals.

Now you can consider replacing the wire... in my opinion any quality wire will be an upgrade and of little consequence.

How to hook them up:

After all that, you will need an active or line level passive crossover. The JBLs of the era will not likely be at a performance level commensurate with your existing electronics. The JBLs are also balanced with required pro audio drive levels... you will probably get hum and be disappointed. Bryston, Marchand, Pass Labs/First Watt are all top flight crossovers. You will need one that is adjustable or order it per JBL specs.

Now you can think of your amplifiers. Oh yeah, that... both the LP and HP sections of this speaker are 96dB or higher at 1 watt/m. If you do not plan on playing higher than 96dB which is quite possible, you can get away with very few watts. That said, you do need to be able to control the back EMF of the woofers so amps with higher damping factors are better suited.


Widget

Woofers are 2225H rec-coned by someone who knows what he's doing with the correct kits to 2235H.
All drivers are said to be working properly. Will check them at next opportunity.
Regarding the crossover, my preamp does have a balanced output. In your opinion can I get away with something like the current production JBL/Harmon 223XS or 234S? They are 24dB L/R.

[markd51]

Replacing the wiring is the easiest thing you can do, upgrading the caps is probably the next easiest thing you can do, but let's step back and put things in order of importance.

Driver status:

The woofers. Are they still 2235H woofers with original cones and mass rings? Have they they had new surrounds put on them or aftermarket kits?

The 2202H, these are very likely fine, as long as there is no sign of visible damage. These speakers have long lasting cloth surrounds and long lasting ferrite magnets.

The 2441 drivers. Likely 50/50 that they will need a rebuild. Original diaphragms are hard to come by, there are the Truextent diagrams at a premium cost and performance change.

The 2405H drivers. Likely damaged or out of spec. Impossible to repair at present. The only solution is to look for suitable replacements with verified performance.

The Networks:

Best option is to pull the originals and keep for collectors value.
Replace with charge coupled networks.

Clean/replace the L-Pads.
Clean/replace the input terminals.

Now you can consider replacing the wire... in my opinion any quality wire will be an upgrade and of little consequence.

How to hook them up:

After all that, you will need an active or line level passive crossover. The JBLs of the era will not likely be at a performance level commensurate with your existing electronics. The JBLs are also balanced with required pro audio drive levels... you will probably get hum and be disappointed. Bryston, Marchand, Pass Labs/First Watt are all top flight crossovers. You will need one that is adjustable or order it per JBL specs.

Now you can think of your amplifiers. Oh yeah, that... both the LP and HP sections of this speaker are 96dB or higher at 1 watt/m. If you do not plan on playing higher than 96dB which is quite possible, you can get away with very few watts. That said, you do need to be able to control the back EMF of the woofers so amps with higher damping factors are better suited.


Widget

Mr Widget, may I ask a question for educational, and knowledge's sake about the mention of Charge Coupled Crossovers, and let's say for these types of 4300 Series Speakers, which appeared to use a myriad of electronics, inboard and outboard.

In simplified layman's terms, and let's say for this particular 4355 Speaker, is this type of network a simple "plug and play" replacement for the original goodies, meaning that once you make all connections to Drivers and L-Pads, would this speaker then be like say a simpler L-100/L-200/L-300 Speaker, you now have two Binding Posts at the rear, plug in an Amp of choice, and play away?

Or no? That the CC network merely replaces the 3155 Network, and one still needs an outboard unit for the low frequency drivers?

The 4355 is actually what, a 4-way system, correct?

If the answer to my questions are no, are there other options? Couldn't a simpler 4-Way Crossover be built? Wouldn't such be known as to what values of inductors-caps ect would be needed?

Maybe I know not of what I speak, but isn't this particular speaker's bass drivers wired in such a unique way that only 4 ohms is present? What if they weren't?


Hope you haven't minded these questions.

[Mr. Widget]

Woofers are 2225H rec-coned by someone who knows what he's doing with the correct kits to 2235H.
All drivers are said to be working properly. Will check them at next opportunity.

Good luck, it is just that with any 30 year old plus gear, in my experience even when presented as mint or "properly working" it is rarely up to original spec without having a true expert getting "under the hood" and replacing or adjusting bits and bobs.

Regarding the crossover, my preamp does have a balanced output. In your opinion can I get away with something like the current production JBL/Harmon 223XS or 234S? They are 24dB L/R.

My preamp is also one with balanced outs... I still sometimes have hum issues with pro gear.

I would suggest buying a cheap JBL or other pro active crossover and get the speakers running. Any active crossover that will let you set ~290 Hz at 12dB, 18dB or 24dB/octave will get you started. You can and will likely upgrade later if you keep the speakers.

Lastly, I posted the detailed driver list etc. post earlier to put things into perspective as you were asking about wiring etc. If they were my speakers, I'd go down the checklist in that order and then look at the "upgrades". Also, realize these speakers were virtually never deployed where the rack didn't also include 1/3 octave or parametric EQ which were used to balance the speakers in the purpose built mixing/monitoring suite.

After you get them up and running, like most of us here, you will likely appreciate their dynamics and find them very satisfying at first, I'll be curious about your feelings about them after an extended period. If you are fortunate enough to get a really good set, they will bring hours of fun, probably a bit of frustration, and then you will need to decide if they are worthy of the real estate that they take up.

Please keep us posted on your journey.


Widget

[Mr. Widget]

Mr Widget, may I ask a question for educational, and knowledge's sake about the mention of Charge Coupled Crossovers, and let's say for these types of 4300 Series Speakers, which appeared to use a myriad of electronics, inboard and outboard.

In simplified layman's terms, and let's say for this particular 4355 Speaker, is this type of network a simple "plug and play" replacement for the original goodies, meaning that once you make all connections to Drivers and L-Pads, would this speaker then be like say a simpler L-100/L-200/L-300 Speaker, you now have two Binding Posts at the rear, plug in an Amp of choice, and play away?

Or no? That the CC network merely replaces the 3155 Network, and one still needs an outboard unit for the low frequency drivers?

The 4355 is actually what, a 4-way system, correct?

If the answer to my questions are no, are there other options? Couldn't a simpler 4-Way Crossover be built? Wouldn't such be known as to what values of inductors-caps ect would be needed?

Or no.

First to be educational to those who haven't been carefully reading this and other audio forums for the past couple of decades. Let me back up; an 8 ohm 1200Hz crossover is not an 8 ohm 1200Hz crossover. In all high quality speakers built today, you have filters, padding, response tweaking, and impedance massaging components that are specific to the drivers, the cabinets, and even the physical layout of the drivers on the baffle.

A CC or charge coupled network is simply a network where you use twice the capacitors and insert a DC voltage between them. (It is a little more complicated than that, but not much) This is a design topology that was created by Ed Meitner and used to good effect by Greg Timbers on a number of his designs.

Regarding the 4355 and it's 3155 network, it was no accident that JBL did not include a passive filter between the dual 2235Hs and the 2202H in these speakers. The components to do this are very large and costly and will not work as well as using an external active filter. Yes, the 4355 is a four way as JBL plainly describes it, and yes it is a 4 way with a three way passive network and dual sets of inputs for bi-amplification. In the 4330 and 4332 speakers they left out the woofer to mid filters and included dual sets of binding posts for bi-amplification, and in the 4345 and others they had a switch to allow for bi-amplification. In the JBL Everest 2 speakers they were all designed with bi-amplification as an option and for these speakers you remove a jumper which deletes the filter between the dual woofers and the HF section. If possible multi-amplification is often desirable though it requires a fair amount of user involvement to get it right.

I hope I have satisfactorily answered your questions... to me it feels as though we have flogged this one thoroughly to death. Maybe its helpful?


Widget

[markd51]

I should of perhaps further asked, that a Charged Coupled Crossover is basically a more sophisticated type of a "Passive Crossover"? Correct? It looks like Kenrick has gone down such paths.

[speakerdave]

Woofers are 2225H rec-coned by someone who knows what he's doing with the correct kits to 2235H.
All drivers are said to be working properly. Will check them at next opportunity.
Regarding the crossover, my preamp does have a balanced output. In your opinion can I get away with something like the current production JBL/Harmon 223XS or 234S? They are 24dB L/R.

Are the 4355's in question reproductions?

[markd51]

Or no.

First to be educational to those who haven't been carefully reading this and other audio forums for the past couple of decades. Let me back up; an 8 ohm 1200Hz crossover is not an 8 ohm 1200Hz crossover. In all high quality speakers built today, you have filters, padding, response tweaking, and impedance massaging components that are specific to the drivers, the cabinets, and even the physical layout of the drivers on the baffle.

A CC or charge coupled network is simply a network where you use twice the capacitors and insert a DC voltage between them. (It is a little more complicated than that, but not much) This is a design topology that was created by Ed Meitner and used to good effect by Greg Timbers on a number of his designs.

Regarding the 4355 and it's 3155 network, it was no accident that JBL did not include a passive filter between the dual 2235Hs and the 2202H in these speakers. The components to do this are very large and costly and will not work as well as using an external active filter. Yes, the 4355 is a four way as JBL plainly describes it, and yes it is a 4 way with a three way passive network and dual sets of inputs for bi-amplification. In the 4330 and 4332 speakers they left out the woofer to mid filters and included dual sets of binding posts for bi-amplification, and in the 4345 and others they had a switch to allow for bi-amplification. In the JBL Everest 2 speakers they were all designed with bi-amplification as an option and for these speakers you remove a jumper which deletes the filter between the dual woofers and the HF section. If possible multi-amplification is often desirable though it requires a fair amount of user involvement to get it right.

I hope I have satisfactorily answered your questions... to me it feels as though we have flogged this one thoroughly to death. Maybe its helpful?


Widget

Thank you,
Some of my questions that I pose are just hypothetical ones and as if I am somehow placing myself in the original poster's shoes by asking a number of my questions in hopes he also benefits and gains knowledge.

Somewhere along the line in a youtube vid recently, I seen custom made passive crossovers for either the 4355, or 4350, might've been by Kenrick in Japan.

Very possibly all they are though, is some form of cloning of the requisite and factory 3155 Dividing network?

I understand, and I'm fully on board that if they were mine, I'd surely wish to do the right things, and not hack such a special pair of speakers with some unorthodox makeshift components in hopes of getting proper joy from them.

[markustubesnow]

Sorry for the 90 degree tilt. First picture I've uploaded here, and I obviously don't know what I'm doing.

Are the 4355's in question reproductions?

[markustubesnow]

Yes, I know the room is a mess. It's a working writing studio.
See if I can get these photos to load properly.

[speakerdave]

Fabulous workspace.

[speakerdave]

I really understand the logic of your choices. You have cozy-up speakers and include-everybody speakers. When you get the the 4355's set up with some amps you'll have blast-off speakers whenever needed.

For my 4345's I used JBL/UREI 6260 for the woofers and Audio Research VT60 for the midrange/treble (with TAD beryllium, but that's another story). With two 2235's each side, 300 watts into a four-ohm load would be handy for the occasional countdown and not very hard to find; Bryston is good. I believe I still have a JBL/UREI 5234A here somewhere, with handloaded cards for the 4345/4355. Not the last word in sound quality, but it will get you going. If you'd like to borrow it, PM me.

[markustubesnow]

But I am pulling the plug.

Why? What was it someone said? "Biting off more than I can chew...?" Yes, I think that's where I was headed.

Frankly, my spirit is feeling much more at peace with this decision than the anxious feelings I was having when I was anticipating everything involved. Your counsel has helped me feel confident making this decision.

For those who are interested, here are some considerations:
1. The speakers are very big. Just getting them fitted into my music room was going to be a hassle.
2. The cost and expense of the speakers is only the first step of several steps. I'd be looking at many more dollars to get them up and running correctly with decent crossovers and amps.
3. There's always the question of the condition of the drivers. A potential headache I really don't have the to appetite to address. The unknowns make what should be quite a bit of fun a bit too stressful.
4. Many of you asked keen questions that reflect your greater experience and understanding. Very helpful for me to see the bigger picture.
5. My wife. Yeah, she'd put up with it. But the prospect wasn't exactly contributing to the harmony in the household.
6. The fact of the matter is I'm actually very content with my existing equipment and two "opposite" systems. I'm sure the 4355s would be better than what I have but to get there it's quite a climb.

Thanks, all, for your generous sharing of wisdom, perspective and insights. Frankly, I feel like I've avoided a potentially costly (in money, time and energy) journey.

[Riley Casey]

Discretion, valor, etc.

If the room pictured is where you intended you use the 4355s this is a good choice. These monitors were intended for use in large studio control rooms where the listening distance was usually 15 ft minimum from the listening area behind the console and the speakers in their soffits. These were never meant to be listened to in the near field with so many drivers needing to combine their outputs in the voice range. The size and component choices were specifically for listening at high SPLs in a fairly large space and your room just doesn't look like that.

But I am pulling the plug.

...

Thanks, all, for your generous sharing of wisdom, perspective and insights. Frankly, I feel like I've avoided a potentially costly (in money, time and energy) journey.

[markd51]

Well, we tried.
One question you never clearly answered, perhaps doesn't make much difference in some ways, but does in some other ways.

Are those Cabinets original JBL, or repros?

That's OK if you want to pull the plug, and no harm, foul, or bad feelings, at least not by me, and with trying to help in what ways that I could.

In life, we've all had to pull some "plugs", bit off more than we could chew, that Time share in Sannibel Island, that nice Ranger Bass Boat, that Motor Home, that House, that Amplifier, that Shotgun, that Turntable, on and on.

Don't forget that in the interest-prospect of throwing in the towel on such a project, and that you've chosen another direction, there might be 3 dozen other members here chomping at the bit to take up such a project, and have your problems to sort through.

There's no doubt members here that eat such problems like a kid eats candy. And I say that with my highest respect of them.

Thus, do seriously consider offering your Speakers to members here first, before you select other avenues.
You'll most likely come out of this fully healed, and get a clearer picture of where you might like to head down the road?

Who knows, maybe a pair of Tannoys, Martin Logans, Magnepans, KEF, B&W, etc are in your future, something else for you will be a better personal fit, and that it is something that doesn't quite interrupt your lifestyle, and harmony.

Best of luck!