4345 power requirements

[Robh3606]

If you remove passive crossover you will find with professional test equipment that the passive crossover was contributing to the end result due to the behaviour of the filter elements and their impact on the drivers behaviour. Some of the effects are not so much voltage but effects on the dynamic behaviour of the drivers.

Hello Ian

I have a question on this. From my understanding you are speaking about analog active crossovers where you just did the curves for those 3 systems. If you look back on the all of the analog crossovers used by JBL including the DX-1 to use the crossovers for different systems all you did was change the cards.

The card themselves were primarily passive components used to adjust the crossover slopes and add some tailoring of the response. A notable exception is the op amp in the DX-1 LF card where you could add bass boost on a couple of the older statement systems like the K2 9500. You also had an option in the 5234/35 of adjusting the LF response with several different Q filters available with an internal selector switch. This option was independent of the cards unlike the DX-1.

The purpose of the cards was to obviously provide the correct voltage drives for each system. The only thing the cards change is the voltage drive. They don't take into account any issues with respect to the different drivers used in multiple systems aside from providing a voltage drive that delivers the same acoustic response as the passive system.

The only way they can address dynamic issues from the drivers would be to adjust the voltage drive to account for any changes between the passive and active versions.

So how would you address dynamic issues with individual drivers with an analog crossover? There are no notch filters available with any of these cards to address specific driver issues. They are all crossover slopes, LF tailoring for in room response, or providing a curve for CD compensation/Power response but little else.

Doing something different?

Rob

[Ian Mackenzie]

Hi Robert,

I can’t comment on those examples without a detailed look at the original passive voltage drives and the active voltage drives.

In the example of the Everest it’s quite a sophisticated system and there were a number of changes.

So we designed a new crossover from scratch with sophisticated functionality for those systems. We then scaled that up to a chassis that can be customised for virtually any loudspeaker.

Of course anyone can do whatever they like but it won’t be what the original engineer/designer intended. Not even remotely. I will talk about that in the Webinar.

There are things you can do actively that you just can’t do with a passive system. Often an engineer will design a system as an active or ideal design. Then adapt it to be a passive system to gain market acceptance. But it will have some compromises. The market doesn’t know what the ideal system was during development so that doesn’t matter.

The key is to engage the original engineer/ designer when converting a passive system to an active system. This applies to any brand or design. If you look at the M2 it was not released with a passive version. But the active design is quite unique. An passive version would have been quite a different take on how it was implemented. That’s where l am coming from.

[markd51]

I was there for that concert as well as the one ELP did at the Long Beach Arena a couple weeks before. Did you spot me in the audience?

I seen ELP at the now long gone Chicago Ampitheater. I think they were set up in quad sound, and had something like $2M in the sound system. About all I do remember, was massive stacks of JBL drivers everywhere. Huge Bass Bins and Horns.

I had a broken seat, bummed me out for the first ten minutes, the usher brought me a crap cratchety old wooden chair to sit on, but after they started playing, I really didn't give a shit.

I smuggled a pair of 10x50 binoculars into that concert, and recall that Carl Palmer was a blur! And I've seen and witnessed some of the greatest drummers that have ever lived, being a drummer myself and studying for 5 full years at Frank's Drum Shop in Chicago.

I once sat right next to Buddy Rich, and arm's length away at a Drum Clinic at Frank's, on his drum stage. That was fall 1967. At that point, I had been studying for 1-1/2 years. I'd say Carl's proficiency came mighty close to Buddy's.

I recall coming home that evening after the concert, spinning a bit of ELP to compare, and my system then, with 2 Mac MC-2105 Amps, and 4 L-65 Jubals, my system sounded "very weak"! I'd say that concert might've caused permanent hearing damage, I wasn't hearing right for 3 days after.

Sure wish I had been smarter back then, and at least brought a pair of ear plugs along.

[toddalin]

I seen ELP at the now long gone Chicago Ampitheater. I think they were set up in quad sound, and had something like $2M in the sound system. About all I do remember, was massive stacks of JBL drivers everywhere. Huge Bass Bins and Horns.

Both Long Beach and the Ontario Jam were in their quad set-up and they ran the music around you. Pink Floyd also used to do this and had a quad set-up for the "Wish You Were Here" tour I saw at the Los Angeles Sports Arena.

I would say that my living room bests any concert that I've ever been too, as any good system really should. Concerts are never ideal.

[markd51]

I know I can't talk shop with some of the masterful minds here who probably forgot more than I'll ever know about speaker design, JBL's history, the particular speakers they made over the years.

OK, in a nutshell, a passive crossover lacks. Is that the case with all speakers past and present? That the crossover is "shortchanging the specific drivers? If so, then in what way?

L-Pads were a compensatory device, but good or bad? Or like what I understand were a mere band aid. That there's better ways to fine tune a mid or high frequency driver if one is willing to swap out crossover components.

One issue at hand, seems to be integration of the drivers, their crossover points, etc. And it seem the more drivers with a speaker, the more monkey wrenches to screw the pooch, and a high liklihood of thing going south, correct?

I have to question, is it then cutting hairs, and chasing the dragon? I can understand the desire to squeeze the best performance for such speakers. How much can be gathered, gained, heard, good for the drivers, or bad, and all the numerous other shortcomings in a specific system, amplification, room acoustics, source components, wiring-cabling, and in the end, can the end user justify the costs? Or the time invested as well? We're only here for a cup of coffee.

Is it then trying to make a silk hat out of a pig? Is there an end to the means? Or per end user, was the honkin huge JBL speaker a mistake? That another speaker might've served an individual better?

How much does one want to toss? $20K, $30K, $100K, $200K? Cable rolling, tube rolling, amp rolling, speaker rolling. We are a sick bunch, aren't we?

Like I was once told back in '74, "what do you want, bells and whistles, or good sound?" And what will it take? That was the old man manager "George" at MusiCraft on Oak street in Chicago, where he took me upstairs, and I blew $2400 dollars that morning on Amps and a Preamp, at age 19.

I had just dumped a $1250 Marantz 4400 Receiver ten mnutes earlier that broke under warranntee, the CRT went to shit, and I was through with that junk.

I thought of such myself. Go back to a Sansui 7 Reciever, and at 66 years of age, I think maybe it's time I stop chasing the dragon. Maybe I'll spend some money at the weed dispensary, and visit 1974 all over again and say Fug Eeet!

Everything's on sale! Maybe just dead weight I'm carrying around too!

Thinking of spending $4K to $5K on a shunyata line conditioner, somebody slap me please.

[Riley Casey]

Your local food bank could probably put $4-5K to better use than an AC line conditioner. Hows that for stopping you?

Jeez, I thought the hocus pocus around speaker cables was bad...

[QUOTE=markd51;436861...

Thinking of spending $4K to $5K on a shunyata line conditioner, somebody slap me please.[/QUOTE]

[Ian Mackenzie]

On the topic of the crossovers and Mr Widgets early post this is my perspective.

Active crossovers were originally used in early all analogue pro PA systems.

In the audio amateur hobby space, the active crossover application is a continuum spanning at one end simple bi-amp operation of bi-amp capable loudspeaker systems to serious audio amateur projects at the other far end which are fully active. In the middle is the thinking customer as Nelson Pass affectionately calls them who are a bit more adventurous. This user will start out in a bi-amp situation with a consumer or pro loudspeaker like a JBL 4333 and then upgrade the compression driver to a two inch driver or perhaps a combination of a different driver and horn and possibly an improved woofer.

This would normally require a re-design of the existing passive crossover and the EQ on the horn. However, this is a barrier for the vast majority of audio amateurs without engineering skills and specialised test equipment.

The active crossover can bridge this barrier with pre-engineered crossover points and EQ for a specifically recommended driver / horn upgrade or an adjustable module is available with a reasonably competent measurement tool as a package. The user is offered some tutorials on how to setup and adjust the module with the measurement package.

The serious audio amateur is a user who has the desire to mould his or her own loudspeaker project and will acquire a variety of drivers for the project. Adjustable modules are provided along with competent measurement tool as a package. Technical/engineering support is available on request.

The users are not left to figure it out for themselves by way of recommendations for particular situations and technical support on request so the user is steered in a direction that will most likely succeed.