Originally Posted by markustubesnow
Hmmm. My wife once commented that stamps or coins might be an interesting collectible. I was only at the 4333A stage then. 4345's and stacks of plain plywood boxes topped with horns came later.
"Audio is filled with dangerous amateurs." --- Tim de Paravicini
So thanks you two for making me feel sorry for participating, sorry I cannot keep up with the self annointed hoi poloi.Replies #2 and #3 were sufficient... helpful as the rest was intended.
There are two sets of speaker inputs for each speaker.
One pair of terminals goes to the woofers directly (IIRC). The other goes to the internal, passive crossover (drives -only- the 12", the horn and the tweeter). They are electrically separate.
That is why you will need an electronic crossover and a 2nd amp. One amp to power the woofers and one amp to power the crossover and the remaining speakers. The electronic crossover accepts your preamp signal, and then it sends LF to the woofer amp and everything else (above 290-300Hz) to the amp for the MF/HF/UHF network and drivers.
I (sort of) humbly suggest you stay out of rewiring, crossover updating, or other value reducing endeavors, until you understand how it all works and you get some satisfactory sound out of them. They worked just fine in state of the art recording studios at the time... weenie cables and all. Might have to check connections at or inside drivers if some element isn't playing (and L-pads if not working properly).
Attachment 89023
If you subsequently wanted to go bonkers with the passive crossover portion
http://www.audioheritage.org/vbullet...l=1#post415320
It's no wonder why my post count is so low here
To re-hash, although the 3155 Network is supposedly present, this is only a dividing network to provide proper frequencies to all other drivers "other than the Bass Drivers:, correct?
And that is why a external crossover is still needed, to "only" provide the required low frequencies suitable to drive Woofers, correct?
My ignorance only shows because I never owned such a pair of speakers, and how the internal networks are engineered and laid out. I no doubt would've known this by simply reading the factory brochure had I had such in front of me.
I'm not as experienced as some or many here, but don't place me in the mongo category just to make yourselves feel high and mighty
Don't stop commenting and sharing your thoughts. I've found them thought provoking and stimulating.
This:
Right? This is pretty much what I was thinking. And I was able to read the factory brochure for the first time last week. It does not say an external crossover is required. It does say bi-amplification is required. Perhaps they assume that any experienced user/sound engineer would already be aware of the need for an external crossover so they don't think it's necessary to mention it.
The 4350 and mildly updated 4355 were never intended for consumer use. The documentation certainly assumes the reader understands the difference between passive and active networks, balanced electronics, and how to use an external equalizer and measurement equipment before powering up the speakers for music playback....This is pretty much what I was thinking. And I was able to read the factory brochure for the first time last week. It does not say an external crossover is required. It does say bi-amplification is required. Perhaps they assume that any experienced user/sound engineer would already be aware of the need for an external crossover so they don't think it's necessary to mention it.
As has been stated before, these speakers are anything but plug and play.
Widget
Hi Mark,
My prior post was to convey a sense of being open minded about your new possessions.
Sometime ago a friend who has been a Quad owner of thirty years heard a similar 4 way Jbl system to the 4355 and was impressed. Some people stack Quads to improve the dynamic range. A more elegant approach is a more efficient loudspeaker.
If you go to the forum library there is a whole section on the 4350/4355 and how they came about.
It’s worth a read to get a perspective on the strengths of this system.
My approach with these multi way systems is to respect the design by using it correctly in the first I instance. A lot of users skip that step and then end up being disappointed.
An important consideration is to understand how to deploy the 4355/4350 in a domestic setting.
The majority of vintage users simply put them on the floor. However in a professional application they are inverted and mounted overhead or SOFIT mounted into a wall. This was common practice.
One of the benefits of the above approach is to control the behaviour of the loudspeaker in the room below 250 hertz and to position the mid high frequency array such that it fires directly to the listened well clear of any larger flat surfaces like a floor.
Why is this important?
The baffle on the 4355 is huge and larger than any other jbl monitors. That’s good and bad.
A loudspeaker baffle has a huge impact on the low frequency behaviour of a loudspeaker once placed in a real acoustic environment. Such large baffles act as an acoustic reflector in the environment and couple to room boundaries very easily. In comparison a small or narrow baffle was as a diffraction lens.
So what does this mean?
The science behind this is saying keep this loudspeaker away from room boundaries.
That is not going to be very practical in a domestic living room. However some relief can be obtained by placing the system on a suitable support to get it off the floor. Like two crates to evaluate the effect. Bringing the enclosure out from the wall behind it will also have an effect.
Subjectively the effect is ghosting of the bass, mid bass and midrange. The loudspeaker will sound dull, blurred and lifeless.
That is my tip before you make any lasting impressions.
The next most important thing is the active crossover.
If your used to the transparency of the Quads a mass market electronic crossover is a No No.
Those drivers deserve better and it can be done without a huge outlay. The link below is to a small business that is making modules that can be easily used to build up a high quality active crossover and they offer support too. The actual integrated circuits used a very good audio grade that are used in premium hifi equipment.
Noise and transparency is the problem with active crossovers. They tend to scrub the sound of all the fidelity. The problem is hidden in that many users assume the active crossover is transparent and they are none the wiser. Wrong.
I purchased these modules late last year but have not had an opportunity to evaluate it yet. All you need to do is put in in a metal chassis. There are organisations that do that with custom milled holes for the connector.
These modules will out perform the common Ashly analogue crossover.
You can also try the DBX drive rack or the BSS Blue digital crossover but they are more complicated to set up.
As l have stated keep an open mind and above all give it a fighting chance.
https://www.xkitz.com/collections/ac...i-amplifiers-1
Hey markd51. Wasn't personal... There's just a lot to sort through and it seemed like there was a lot of information flying around. Thought some focus might be helpful.
The 3155 crossover is better than the prior version but uses Mylar capacitors bypassed by small value polypropylene caps.
Great back in that era. But again they muffle the sound (yes you can actually hear it) and you might be tempted to move them on. There are forum members around who can help you sort the crossover. The wire is fine.
They have a big sound. But beyond that the more you understand this loudspeaker the more you will get out of it in terms of musical enjoyment.
Thank you for consideration and also the technical info behind these Studio Monitors.
If anything, and if I was in the original poster's situation, I'd probably take a step back. And as well, let's for say if such speakers were acquired personally I bought them with an offer that I just could not refuse, I loved them, but perhaps at current day they weren't a fit. Then I'd maybe sit on them for a length of time, contemplate what my options were.
Maybe in the end, I might possibly conclude that I bit off more than I could chew, and I'd release them to their "rightful owner". I am well aware, that speakers such as these will never depreciate!
I gather Mr Greg Timbers was associated with this design throughout. They are like a rare Duesenberg, Auburn Speedster, maybe copied, but never aagin to be truly duplicated and realized.
Again my apologies, I am often said by some to be a quite condescending person, I try very hard not to be.
I thought I could offer some food for thought and some small shred of help and ideas.
I cannot afford to play with the big boys, such as some owners of some certain audio forums who have a wall of McIntosh worth a million clams. I'll omit his name here. He'll buy a pair of L-300's for a paltry $5K, buy a Ferrari 458 Italia like I bought a Polish Sausage on Maxwell St, the finest of firearms, watches, homes (2) Mac 2.5KW Amps, piece of cake. Such people, God bless them, but I'm not one who likes some person rubbing their wealth (or their knowledge) in my face either. It's more a turn off to me.
Again, and to the original poster, I hope my comments have not caused a reluctance of the more knowledgeable members assisting you and then this thread gets flushed down the toilet.
I'll try hard to write less, and listen-read more.
I'd say roughly, I probably have about $30K invested in my system. That's quite far for someone like myself. I'm just an old hack who earned his living working on Trains for 30 years.
Agreed… and although you need no approval from me, you have a very fine system and are obviously concerned to get the most out of it. That comes through loud and clear
As has been stated, there’s a lot involved in just getting such a system as the 4355 just functioning at a basic level, let alone upgrading. That seemed like step 1.
Hoping we haven’t deterred the OP from exploring, experimenting, and coming back with questions, feedback, opinions, and pictures (of course)!
funny… I think the only stereo items I’ve bought new were my L150As and my preamp… oh, and a set Koss Pro headphones and a JCP receiver, haha (high school, making $2/hr)
Geez. Where to start. So much useful information and well-written technical explanation. I'm blown away by your willingness to guide and educate me.
I have been wondering if I've bit off more than I can chew. It would help if my listening room didn't have ~4,000 LPs in IKEA Expedit shelving taking up virtually the whole end of the room (on the end near my preamp, DAC, turntable and amplifiers) and another ~1,500 LPs and hundreds of books in shelving on the other.
I'm thinking I might need to place these speakers on rolling dollies. That would get the bottoms about 8 inches off the floor, somewhat to address Ian's very helpful comments about why they used to be mounted in soffits in the studios.
I followed the link to the 3155-equivalent charge-capacitor network (is that the correct term?) and sent the image to the local Tech for an estimate. In the meantime I followed the link to the Xkitz crossover. Those look awesome and they're not too expensive.
Best regards, all, and many thanks.
Hello Markus
I think we are giving you way to much information. The best thing is to keep it simple. I have attached a thread that has the 4350 Manual. It will work fine with 4355's. Don't get hung up on the active crossover. Just use a conventional analog 24dB L/R like a JBL M552 to get you started. You can do all the refinements mentioned at a later date. Just get them working first!
Dollies are a great idea!
http://www.audioheritage.org/vbullet...highlight=4350
"I could be arguing in my spare time"
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
So, ideally, and "keeping it in the family" so to speak, the missing link would be the JBL Dividing Network?
I looked it up on the 4355 Brochure, the model number eludes me at the moment.
This?
file:///C:/Users/Owner/AppData/Local/Temp/5234a_manual.pdf
Or some more modern form-equivalent that would share the same specs as far as rolloff. Which is what, 12db per octave? Or 18db?
After that electronically, the rest seems easy, two Amps of personal choice, and a good hank of some decent DIY Speaker Cable.
I know there's lot of inexpensive Crown Amps with various models-lines that could work, many now have RCA inputs, and I would think would be compatible with a PreAmp.
I'd prefer something without cooling fans if they can be avoided.
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