tips on bi-amping for newbie

[pyonc]

Hi,

I've recently purchased a 4343 in good condition from a JBL member here.
My goal in the near future is to use bi-amp for these babies.
Can anyone give me a step-by-step guide on bi-amping of 4343 in plain English? I see some threads on this in this form, but as a beginner in this audio world, I find some technical terms such as crossover, etc, rather diffcult to understand. Thanks for your kind and easy-to-understand counsel in advance!

[jcrobso]

To Bi-amp you need an electronic crossover, see the links for an examples, there are other on the market as well.
http://www.mcmelectronics.com/product/555-3141
http://www.sweetwaveaudio.com/sales/rane/ac23b.php

info here.
http://www.scrounge.org/speak/xvrprim.htm

In simple terms you use the electronic crossover (EC) after the preamp, the signal goes from the preamp to the EC the low output of the EC goes to the bass amp, then to the low frequency driver(woofer) bypassing the built in crossover network. The high of the EC goes to the HF amp and from the amp to the high frequency speakers.
There are benefits to by-amping, but there is also costs, the cost of the EC and an additional power amp. Look a the controls on the EC, there are many, it is just as easy to get a bad sound from an EC as it is to get good sound. This is just about as simple as I can make it, setting up a by-amp system with an EC is not hard but it is not simple. :blink:

[pyonc]

To Bi-amp you need an electronic crossover, see the links for an examples, there are other on the market as well.
http://www.mcmelectronics.com/product/555-3141
http://www.sweetwaveaudio.com/sales/rane/ac23b.php

info here.
http://www.scrounge.org/speak/xvrprim.htm

In simple terms you use the electronic crossover (EC) after the preamp, the signal goes from the preamp to the EC the low output of the EC goes to the bass amp, then to the low frequency driver(woofer) bypassing the built in crossover network. The high of the EC goes to the HF amp and from the amp to the high frequency speakers.
There are benefits to by-amping, but there is also costs, the cost of the EC and an additional power amp. Look a the controls on the EC, there are many, it is just as easy to get a bad sound from an EC as it is to get good sound. This is just about as simple as I can make it, setting up a by-amp system with an EC is not hard but it is not simple. :blink:

Thanks for your kind advice.
Let me ask you one more. If you look at the back of the 4343, you have four terminal inputs for biamp. The one set of black, red terminal input in the lower section is intended for just single amp mode, which I use right now. So, if you want to set it to bi-amp, first you adjust the switch from the INTERNAL CROSSOVER to Exernal Crossover, right? And then? Hooking the power amps with the speakers? What about the EC frequency adjustments? Don't you have to touch the wiring of the woofer, etc inside the back, which I read somewhere in related threads here...

[Mr. Widget]

Let me ask you one more. If you look at the back of the 4343, you have four terminal inputs for biamp....Post a photo please... not all of us remember what every JBL crossover looks like... and sometimes there are differences within a model. A photo would help clarify things. :)


That said, why do you want to bi-amp? What are you hoping to gain?


Widget

[pyonc]

Post a photo please... not all of us remember what every JBL crossover looks like... and sometimes there are differences within a model. A photo would help clarify things. :)


That said, why do you want to bi-amp? What are you hoping to gain?


Widget

Thank you for the reply, and asking this fundamental question, Widget.
I'm curious if you're against bi-amping. The main reason I want to bi-amp is to get 'better sound' than now, as they say. Almost everyone in this forum says if you do biamp for 4343, you'd get "better sound". And there're lots of threads here on the argument for bi-amping. So, the consensus among the forum members, I believe, is you should do it. I listen to jazz (CDs and LPs) all the time, I'd like to get more targeted, clear and dynamic sounds of keyboards, horns and percussions, etc from each of this low, mid, high, and ultra-high driver of 4343 through bi-amping. Currently my 4343 is in sigle amp mode, namely the speaker wires simply hooked to the black and red terminal inputs with the switch set to internal crossover on the back. I see the mark System Crossover 300hz on top. What does this mean when bi-amping? See the attached pics.

[richluvsound]

I think you'll also read that bi-amping for critical listening requires a very good quality xover . Marchand, Bryston , Pass labs , Deqx.

Have you considered Charge Coupling the networks ? Many here have used this upgrade with more than glorious results .

You will gain tighter definition around the 300 hrtz range from external and thats about it .

Others may have other opinions though. Even with an expensive 2- way external you will still have the network the original internal dividing the signal between the 2122 and the 2405 ...

Sure you can go for it with the 5235 ,but you will also read a great deal about that option here too. Why put more 20 year old electronics in the signal path though !

Rich

[jcrobso]

This means that the passive crossover in the box is at 300Hz, if you bi-amp you must set the EC at frequency that is higher than 300hz.
I do bi-amp my big SR system, I use an EC set at 100hz to feed the sub and the mains are passive.

[Doc Mark]

Morning, Pyonc,

When I read your questions, it reminds me of me, quite a few years back! ;):D I still have much do learn, as do we all. But, if I may offer a suggestion? Try to find some basic books which describe the information you are seeking. If you don't understand the basics, then many of the terms that we will use to help bring you up to speed will not be understood, either. Nothing wrong with not knowing, as nobody will ever know it all, and each of us is on our own personal learning curve. But, do yourself a favor, and before jumping into waters that may well be way over your head, learn the terms, meanings, and jargon of the basics. After that, it will be much easier to answer your questions, and in fact, you may well find your own answers in your studies. Best of luck, and have fun learning and getting your system setup as you wish it to be! Take care, and God Bless!

Every Good Wish,
Doc

[Mr. Widget]

I see the mark System Crossover 300hz on top. What does this mean when bi-amping? See the attached pics.It is simply JBL's way of telling you that the design calls for a 300Hz crossover. There is an internal crossover set to that frequency, when you go into bi-amp mode, that circuit is removed, and you replace it with your active crossover and two amps. The other crossover components that divide the frequencies to the compression drivers are all still in the circuit as they should be. Simplistically what you do is send all frequencies above 300Hz to the top pair of binding posts and all frequencies below 300Hz to the bottom pair of posts.

This is the simple part... read on!

I'm curious if you're against bi-amping.On my shelves of gear in the basement I have at least 5 electronic crossovers. I have bi-amped and tri-amped many of my systems over the years... so no, I am not inherently against bi-amping.

The main reason I want to bi-amp is to get 'better sound' than now...That's a good reason, and it is possible to improve the sound of these speakers by bi-amping.

Almost everyone in this forum says if you do biamp for 4343, you'd get "better sound". And there're lots of threads here on the argument for bi-amping. So, the consensus among the forum members, I believe, is you should do it.So you are prepared to trust a bunch of strangers you have never met? :D

First off, just because a pile a yahoos on the internet tell you that X will happen if you do Y, it just doesn't make it so. That said, I'll give you this yahoo's opinion on the matter.

As Rich said, there is cost and complexity involved in going with a multi-amped system. Is it worth it and will it improve the sound of your system? Not necessarily. As a newbie, the likelihood of your nailing it and getting it right the first time is low. How do all of these other newbies do it? There is a lot of placebo effect out there in audioland. I bet if many owners heard their systems in a blind comparison, they'd prefer the factory crossover to their "improved" system, but it is a hobby, and if they "think" it sounds better, then I guess it does. :)

OK, so on to the complexity. Obviously you will be adding an amp and the crossover. This adds the inconvenience of power on/off sequence and number of switches to fool with, but all in all not a big deal. What typically is a bigger deal is that with a multi-amped system you also increase the likelihood of adding a grounding issue, gain structure issue or both. Most multi-amped systems I have heard have gain structure issues and many have grounding issues. Both of these mean noise. If you set up the system correctly and you are using high quality gear, you should be able to add these bits and not increase the noise floor... but it just isn't that simple. It gets worse when you start mixing home audio and pro audio gear... they have different grounding schemes and different line levels.

OK, the cost. If your primary system is made up of a decent preamp and a good power amp, and you add a Rane, or an old JBL pro unit, or a digital Behringer, or even the pretty decent Ashly XR-1001, you have just taken the output of your pre and run it through a grunge circuit... why would you want to do that? Now if you are not using a decent preamp and amp, STOP! Stop reading this, and go improve your electronics before proceeding. And don't short change your source. Assuming you are using CDs, I recently bought a new DAC... a much bigger improvement than adding an active crossover. ;)

OK, so you want to continue... I would get a Marchand, Pass Labs, or Bryston crossover. All of these are moderately expensive, but if you don't go this route you are stepping backwards. There are a couple of vintage alternatives that I have had excellent results with, and they are relatively inexpensive, but relatively rare (with patience they are available). My first choice is the John Curl designed Symmetry ACS-1 or ACS-2. Second choice is the Dahlquist DQ-LP1. Both of these vintage (all vintage pieces should be as well) should be checked out by a tech and old caps replaced as needed. I am sure there are some other older crossovers that are good, perhaps the old Crown units, the old Luxmans and Pioneers might be good choices too, but I have never heard them myself. (Just writing this I remembered two more crossovers I have downstairs :))

After the crossover is chosen, the next step up is the new amp. This is likely the area of greatest improvement. Here you get to pick an amp that will handle the mids and upper end without being burdened by the bass. I would continue using a big beefy SS amp for the woofer and get a nice tube amp for the top end. This can be a wonderful upgrade.

Now, the next downside... setting it all up. Without test gear, really good ears or both, setting up a multi-amped system is not trivial. You need to pick the frequency and slope that best matches your system, second order (12dB/octave) at 300Hz? That is suggested. Will it be best? Maybe... testing and listening come in here... and then, you need to balance the drivers. Carefully listening you should be able to do this, but you also need to balance them left and right. Even the simple task of getting these levels all balanced isn't trivial.

Is this whole process fun or painful? It can be both... I set up my first tri-amped JBL system about 30 years ago and have had a hell of a great time screwing up ever since. :applaud:


Widget

[4313B]

Can anyone give me a step-by-step guide on bi-amping of 4343 in plain English?You might want to read these since this is where many folks started:

The 5234A Electronic Frequency Dividing Network is designed for ... (http://www.jblpro.com/pub/obsolete/5234a.pdf)

JBL 5234A INSTALLATION AND SERVICE MANUAL (http://www.jblproservice.com/pdf/Vintage%20JBL-UREI%20Electronics/JBL-5234A%20manual.pdf)

5235 manual.pdf (http://www.jblproservice.com/pdf/Vintage%20JBL-UREI%20Electronics/JBL-5235%20manual.pdf)

[Robh3606]

And on the other side of the fence

Just go for it!

Have a listen and make up your own mind if it was worth it or not. You are going to have fun doing it as long as you don't cook something so take your time.

Rob:applaud:

[jcrobso]

You see that this can get complicated very fast!:biting:
My fist experience with an EC was in 1968 I built a EC from a construction project in Audio magazine. Everything went will until we powered off the amps, this was way before protection circuity. The turn off transient dumped the power supply thought the JBL 375 driver and wiped out the voice coil!:shock::(
JBL was very nice fixed one, but I had to pay for the other one. JBL called me at home to ask me how I did this. One month later in Audio JBL put a article advising the use of a capacitor in the HF section.
The moral of the story is to all wise make sure that you have a DC Blocking capacitor in the HF section. I'm fairly sure that all JBL bi-amp speakers have this.

[Mr. Widget]

And on the other side of the fence

Just go for it! Other side? :D

I don't believe I ever said don't do it... I simply, perhaps not so simply, stated a number of conditions required to make it work well. :bouncy:


Widget

[pyonc]

Morning, Pyonc,

When I read your questions, it reminds me of me, quite a few years back! ;):D I still have much do learn, as do we all. But, if I may offer a suggestion? Try to find some basic books which describe the information you are seeking. If you don't understand the basics, then many of the terms that we will use to help bring you up to speed will not be understood, either. Nothing wrong with not knowing, as nobody will ever know it all, and each of us is on our own personal learning curve. But, do yourself a favor, and before jumping into waters that may well be way over your head, learn the terms, meanings, and jargon of the basics. After that, it will be much easier to answer your questions, and in fact, you may well find your own answers in your studies. Best of luck, and have fun learning and getting your system setup as you wish it to be! Take care, and God Bless!

Every Good Wish,
Doc

Thanks for the advice. Actually, I've Robert Harley's Complete Guide to High-End Audio on the shelf, which I turn to sometimes, depending on the topic. Still, I'm often stuck by these technical terms, too. Looks like doing is believeing in this audio world.

[pyonc]

It is simply JBL's way of telling you that the design calls for a 300Hz crossover. There is an internal crossover set to that frequency, when you go into bi-amp mode, that circuit is removed, and you replace it with your active crossover and two amps. The other crossover components that divide the frequencies to the compression drivers are all still in the circuit as they should be. Simplistically what you do is send all frequencies above 300Hz to the top pair of binding posts and all frequencies below 300Hz to the bottom pair of posts.

This is the simple part... read on!On my shelves of gear in the basement I have at least 5 electronic crossovers. I have bi-amped and tri-amped many of my systems over the years... so no, I am not inherently against bi-amping.
That's a good reason, and it is possible to improve the sound of these speakers by bi-amping.
So you are prepared to trust a bunch of strangers you have never met? :D

First off, just because a pile a yahoos on the internet tell you that X will happen if you do Y, it just doesn't make it so. That said, I'll give you this yahoo's opinion on the matter.

As Rich said, there is cost and complexity involved in going with a multi-amped system. Is it worth it and will it improve the sound of your system? Not necessarily. As a newbie, the likelihood of your nailing it and getting it right the first time is low. How do all of these other newbies do it? There is a lot of placebo effect out there in audioland. I bet if many owners heard their systems in a blind comparison, they'd prefer the factory crossover to their "improved" system, but it is a hobby, and if they "think" it sounds better, then I guess it does. :)

OK, so on to the complexity. Obviously you will be adding an amp and the crossover. This adds the inconvenience of power on/off sequence and number of switches to fool with, but all in all not a big deal. What typically is a bigger deal is that with a multi-amped system you also increase the likelihood of adding a grounding issue, gain structure issue or both. Most multi-amped systems I have heard have gain structure issues and many have grounding issues. Both of these mean noise. If you set up the system correctly and you are using high quality gear, you should be able to add these bits and not increase the noise floor... but it just isn't that simple. It gets worse when you start mixing home audio and pro audio gear... they have different grounding schemes and different line levels.

OK, the cost. If your primary system is made up of a decent preamp and a good power amp, and you add a Rane, or an old JBL pro unit, or a digital Behringer, or even the pretty decent Ashly XR-1001, you have just taken the output of your pre and run it through a grunge circuit... why would you want to do that? Now if you are not using a decent preamp and amp, STOP! Stop reading this, and go improve your electronics before proceeding. And don't short change your source. Assuming you are using CDs, I recently bought a new DAC... a much bigger improvement than adding an active crossover. ;)

OK, so you want to continue... I would get a Marchand, Pass Labs, or Bryston crossover. All of these are moderately expensive, but if you don't go this route you are stepping backwards. There are a couple of vintage alternatives that I have had excellent results with, and they are relatively inexpensive, but relatively rare (with patience they are available). My first choice is the John Curl designed Symmetry ACS-1 or ACS-2. Second choice is the Dahlquist DQ-LP1. Both of these vintage (all vintage pieces should be as well) should be checked out by a tech and old caps replaced as needed. I am sure there are some other older crossovers that are good, perhaps the old Crown units, the old Luxmans and Pioneers might be good choices too, but I have never heard them myself. (Just writing this I remembered two more crossovers I have downstairs :))

After the crossover is chosen, the next step up is the new amp. This is likely the area of greatest improvement. Here you get to pick an amp that will handle the mids and upper end without being burdened by the bass. I would continue using a big beefy SS amp for the woofer and get a nice tube amp for the top end. This can be a wonderful upgrade.

Now, the next downside... setting it all up. Without test gear, really good ears or both, setting up a multi-amped system is not trivial. You need to pick the frequency and slope that best matches your system, second order (12dB/octave) at 300Hz? That is suggested. Will it be best? Maybe... testing and listening come in here... and then, you need to balance the drivers. Carefully listening you should be able to do this, but you also need to balance them left and right. Even the simple task of getting these levels all balanced isn't trivial.

Is this whole process fun or painful? It can be both... I set up my first tri-amped JBL system about 30 years ago and have had a hell of a great time screwing up ever since. :applaud:


Widget

Thanks a lot for your kind and detailed explanation on this. I'll try to do so according to your advice and get back to you someday. Reading your explanation, however, I'm afraid I have to stay with single-amp mode for the time being until I get a better sense of the working of this bi-amp, and acquire the right gear you mentioned for this. And I'm expecting to go thorough more pain than joy once I decide to move on to bi-amping...

[pyonc]

This means that the passive crossover in the box is at 300Hz, if you bi-amp you must set the EC at frequency that is higher than 300hz.
I do bi-amp my big SR system, I use an EC set at 100hz to feed the sub and the mains are passive.

Got you! Thanks for the easy explanation.

[richluvsound]

Thanks for your input Widget ...

you have a far greater understanding than I on this subject . I was trying to help based on my experience - experience gleaned from many hours trawling, asking questions here, and trying to implement that advise .

Rich

[pyonc]

And on the other side of the fence

Just go for it!

Have a listen and make up your own mind if it was worth it or not. You are going to have fun doing it as long as you don't cook something so take your time.

Rob:applaud:

Thanks, Rob. I'd rather be cautious before jumping right into bi-amping at this point, even though it's worth it.

[pyonc]

You might want to read these since this is where many folks started:

The 5234A Electronic Frequency Dividing Network is designed for ... (http://www.jblpro.com/pub/obsolete/5234a.pdf)

JBL 5234A INSTALLATION AND SERVICE MANUAL (http://www.jblproservice.com/pdf/Vintage%20JBL-UREI%20Electronics/JBL-5234A%20manual.pdf)

5235 manual.pdf (http://www.jblproservice.com/pdf/Vintage%20JBL-UREI%20Electronics/JBL-5235%20manual.pdf)

Thanks for the info. Actually I recently bought 5233, 5234 on ebay without knowing at all about the exact function of this twin. The reason I purchased them was I read in JBL material that dividing network like this was necessary for biamplification of 4343. Just for the sake of future use. The 5233 shows 800HZ, and the 5234 shows 500HZ on the left, and 1200HZ on the right. I'm not sure what this is all about. Frankly, I regret buying them...

[4313B]

Frankly, I regret buying them...Pass them on then.