4345 power requirements

[Dr.db]

Hello,

what is the optimum power of an amplifier to run the mid-high section of a 4345-monitor?

The 4345 can be used with seperate amps for the 2245 and the mid-high section. There is a lot of talk about the 2245, but how much is actually required to run the midwoofer and horns? Assuming that a active-crossover is used between the woofer and high-mid section at ~290hz....

Best regards,
Olaf

[BMWCCA]

Not sure what's "optimum" but for the past 10-years I've used a Crown PS200 (100-wpc) on the top end and PS400 (200-wpc) on the bottom. Remember Greg's advice to bypass the bi-amp switch for better performance.

Mine play plenty loud and I've never seen the IOC lights on either Crown even flicker. JBL specs call for maximum input power on the upper end of 100-watts but—in typical JBL fashion—call for a 200-watt-per-channel amp to gain that 3dB of headroom.

:dont-know:

[Robh3606]

100 watts should be fine. Ran my 4344 clones that way no issues at all. Would force me out of the room before the amps would clip.

Rob:)

[Dr.db]

100 watts is actually a lot more than I would´ve expected.

I thought you could get away with something like 20-30 watts.
The mid-high section has a higher sensitivity than the bass. And I´ve once read, that you need about 6db less of power in the midrange compared to the bass. In my assumption that would mean aprox. 10db less amp-power for the mid-high-section compared to the bass-section.

[robertg]

For a while I was using a 50w Krell KSA50S for the top end of my 4345 clone. I didn't think more was required.

[Ducatista47]

Twenty-five watt First Watt F5 here. I doubt it has ever been asked to put out five. Very efficient system.

[markd51]

A little bit of headroom is always a nice thing to have on hand.

Or go with the smaller brother, the 7B3.

https://www.tonepublications.com/review/brystons-28b-cubed-power-amplifiers/

[speakermaker]

88979
Ich nutze für den Bass eine Nakamichi PA 7 und für MHT eine Nakamichi PA 5 EII , ich benutze 2123H ,bei denen ich bis auf 200Hz mit der
Ü-Frequenz runter gehe, durch die wandnahe Aufstellung ergibt sich ein durchaus glatter Frequenzgang . Meine 2123 laufen in 15 Litern Volumen.
Grüße aus OWL

[markd51]

I was funnin a bit with my last post, and can understand if splitting the speaker system by bi-amping-etc of course the mids and tweets don't need 100's of watts of power. How much can they take, and as well, how much can your ears take? LOL

Still, headroom (watts and current) provides enough clean power without worry of ever clipping.

[Robh3606]

200 watts is what is recommended on the JBL Techsheet including headroom for a 4345 above 290 Hz. At home? The difference between 25 watts vs 200 watts is about 9dB of additional headroom. So you could only hit 111dB instead of 120dB!

Rob :)

[Dr.db]

Awesome to get to hear what everyone is using with their 4345, thanks!

The Spec-sheet clearly states 200watts (including headroom), can`t argue with that.

I totally believe the 10" midwoofer will handle this kind of power. But I actually doubt it will see this kind of powerlevels in realitiy.
The 2245 is about 3db less efficient than the mid-high-section. Therefor 100watts for the top, 200watts for the bottom. But as I mentioned earlier, mid frequencies are supposed to need aprox. 6db less of power than low frequencies. Or is this snake-oil audio-talk?

[markd51]

Awesome to get to hear what everyone is using with their 4345, thanks!

The Spec-sheet clearly states 200watts (including headroom), can`t argue with that.

I totally believe the 10" midwoofer will handle this kind of power. But I actually doubt it will see this kind of powerlevels in realitiy.
The 2245 is about 3db less efficient than the mid-high-section. Therefor 100watts for the top, 200watts for the bottom. But as I mentioned earlier, mid frequencies are supposed to need aprox. 6db less of power than low frequencies. Or is this snake-oil audio-talk?

What it all basically comes down to in a nutshell, is power handling capacity, and perceived volume at different frequencies.

It's like, walk into a small venue to play guitar in some group with a 85w Fender Twin Reverb cranked to 9, and they'll throw you out of the place on your ear because you'll be killing everyone in the place.

Whereas, it wasn't uncommon for bass amps to be throwing out 600, 800,1000 watts.

Besides too little wattage where you might risk making an Amp clip, which is dangerous for any driver, too much wattage will toast-fry drivers, x-overs, and even L-Pads aren't immune either.

Besides "quantity", good sound does benefit from quality amplification. I'm not of the camp that believes all amplifiers sound the same.

[Ian Mackenzie]

Hi Olaf,

The responses are correct.

It depends on a number of factors such as your listen preferences and the genre of music you listen to. If you have a small room and you only listen to folk music the power demands are going to be relatively small. But if you have a large room and play heavy metal then a margin of headroom is common sense. For example if you play quite loud continuously in a big room the program power could be 50 watts. But the peaks might be 6 dB higher. So that means a 200-300 watt amplifier rating to avoid the possibility of clipping and sending damaging square waves to the drivers.

Technically the mid Lpad gives a -3 dB cut on the zero position. There is also a fixed pad on the output of the 2122. The 2122 filter has some passive voltage gain of about 2db because it’s a bandpass filter.

If you turn the mid L pad up full you reduce power needed for the same sound level by 3 dB or 50%.

I would suggest a minimum of 100 watts be default. But it’s a case by case situation beyond that.

[Ducatista47]

Whenever these massive monitors are discussed re: headroom and clipping avoidance, my first and last thoughts are about being cautious about listening volume. It is not a great idea to drive JBL monitors in the home to any point where you have to worry about clipping. The standard warning in the handouts was that your hearing will be permanently damaged before the monitors will distort. Think about it.

The other thing, those old white papers about clipping damage to the drivers were penned in the early solid state amp era. Those crappy amps would produce really damaging signal when cranked. Use something better and you likely would not hear distortion before the onset of hearing damage no matter how careful you think you are being.

I confess that at many listening volumes I have heard, the first thing I reach for is earplugs.

[markd51]

Whenever these massive monitors are discussed re: headroom and clipping avoidance, my first and last thoughts are about being cautious about listening volume. It is not a great idea to drive JBL monitors in the home to any point where you have to worry about clipping. The standard warning in the handouts was that your hearing will be permanently damaged before the monitors will distort. Think about it.

The other thing, those old white papers about clipping damage to the drivers were penned in the early solid state amp era. Those crappy amps would produce really damaging signal when cranked. Use something better and you likely would not hear distortion before the onset of hearing damage no matter how careful you think you are being.

I confess that at many listening volumes I have heard, the first thing I reach for is earplugs.

Rock Concerts, I've been to quite a few. An ELP concert with the introduction of their Brain Salad Surgery release will make 20 pairs of those 4345 Speakers sound like a 9V Battery Pocket Transistor Radio. Ask me how I know!

https://www.youtube.com/watch?v=wz6Mj8cROJw

[ngccglp]

Hi Olaf,

If there something about the 4345’s sound that prompted the original question?

[Ian Mackenzie]

These things do sound better driven to a level beyond any bookshelf loudspeaker.

The sound gets bigger, not louder. It’s the inherent linearity of the eighteen inch woofer in combo with the other low distortion drivers. Those woofers really couple to the room boundaries. You don’t get the same effect with the DD67000. They have more definition but don’t reach as deep with the same effortless authority.

[Mr. Widget]

what is the optimum power of an amplifier to run the mid-high section of a 4345-monitor?
I have a method I use to determine ideal amplifier power for any system.

1. How sensitive is the speaker?
2. What is the maximum SPL I expect to see?
3. Is this a distributed audio system or Hi-Fi system? Distributed audio get's 3dB of headroom and Hi-Fi 10dB.

The HF section of the 4345 has a sensitivity of 98dB/watt/m
Let's say you want a max SPL at a meter of 106dB... very loud, but not quite rock concert levels.
This is a Hi-Fi system.

Therefore you need ~7 watts to hit your goal of 106dB at a meter and should use a 70 watt amp to give yourself 10dB of headroom.

With this system, I have never had clipping issues or blown drivers.

Obviously you need to match the speaker to the task. If you have a speaker with a sensitivity of 85dB/watt/m and you want 110dB at a meter, you will need ~300watts to hit 110dB and 3000watts to give yourself the headroom. This speaker is most likely not going to give you the SPL you require. At best there will be far too much dynamic compression and very likely you will have thermal failure.


Widget

[Dr.db]

@markd51:
To simplifiy it: When bassdrivers and middrivers have the same sensitivity, the bassdriver will still require a multiple of the power of the middriver for the same level?


@Ian:
I get the idea of the continuous programm power and the occasional peaks being far greater. Good point.
But how do you feel about the frequency depending power requirements? Is the difference between the bass and midregion really only the 3db in sensitivity?
You suggested a minimum of 100watts for the HF. When using these 100watts for the HF, how much do you suggest for the 2245 in this circumstance?

@ngccglp:
Nothing wrong with the sound. I was just wondering if using a little class-a amp with 20watts will work.


@widget:
Your example of 106db SPL at a meter with 10db-headroom indicates 70watts for the HF-section. Sticking to this example, this would indicate 140watts for the 2245, correct?

[Mr. Widget]

@widget:
Your example of 106db SPL at a meter with 10db-headroom indicates 70watts for the HF-section. Sticking to this example, this would indicate 140watts for the 2245, correct?Yes, but I would go with 200 min as any EQ down there will drastically increase your power requirements. Not to mention 200wpc amps are pretty common.


Widget

[Ian Mackenzie]

Hi Olaf,

To answer you question we need to look at how things were done back in that era.

This range of Jbl pro monitors were targeted at the recording industry where high continuous SPL were required and reliability was important.

Those requirements are somewhat more demanding that our vintage legacy listening habits as we will see but the same principles apply.

John Eargle was consulting to JBL at the time and had considerable input on how monitors were used in the industry.

Referring to The Handbook of Recording Engineering a whole chapter is devoted to studio monitors with design examples using bi amp techniques.

I unfortunately don’t have a copy of the text to paraphrase but it was laid out like this.

See next post

[Ian Mackenzie]

To calculate power you work backwards using:
Loudspeaker driver sensitivity
Loudspeaker driver power rating
Listening distance
Available amplifier power
Crossover points

So let’s make some assumptions

The listening position back then was four metres from the monitors in a large control room (a 12 dB reduction in spl taken at 1 metre)

The mix engineer needed 103dB at the desk
The rated sensitivity of the 4345 was 95 dB ( with the Lpads at zero position)

The engineer required a 6 dB margin of dynamic headroom.

In this situation this is what we have:

95 dB @ 1 metre for 1 watt
105 dB @ 1 metre for 10 watts
115 dB @ 1 metre for 100 watts

A 10 dB increase in SPL required x10 amplifier power.

A doubling of the distance is a -6 loss in spl.
Therefore, @ 4 metres the above spl figures become:

83 dB @ 4 metres for 1 watt
93 dB @ 4 metres for 10 watt
103 dB @ 4 metres for 100 watts

See next post

[Ian Mackenzie]

The amplifier requirements back then were a limitation and Jbl was a pioneer in Biamping.
The approach taken at the time was a 300 hertz crossover point was a 50/50 split in the amplifier power rating and a 800 hertz crossover point was a 75/25 in the power rating.

In the text reference is made ( and documented elsewhere) that two 50 watt amplifiers in Biamp operation deliver the equivalent of a 200 watt amplifier.

Why is this?

A 200 watt amplifier must deliver 40 volts rms into an 8 ohm load to deliver 200 watts

A 50 watt amplifier must deliver 20 volts rms into an 8 ohm load to deliver 50 watts.

The voltage crest factor of 6 dB or 20+20 volts =40 volts is the reason behind this calculation.

A doubling of voltage gives four times or a 6 dB increase in rms power to the load.

So taking the above figure of
103 dB @ 4 metres for 100 watts

Therefore,
103 dB @ 4 metres for 2 x 25 watts (crossover 300 hertz) will deliver equivalent output of a 100 watt amplifier.

Then Biamp using two identical 100 watt amplifiers would give a 6 dB headroom factor.

109 dB @ 4 metres for 2 x 100 watts ( crossover 300 hertz)

112 dB @ 4 metres for 2 x 200 watts (crossover 300 hertz)

115 dB @ 4 metres for 2x 400 watts (crossover 300 hertz)

L pad adjustment to max on mid, +3 dB on horn and slot will
reduce the mid high array amplifier power to 200 watts

Note these outputs are far above the capability of a typical hifi loudspeakers regardless of price from 30-20,000 hertz.

See next post

[Ian Mackenzie]

So it’s a matter of looking at your maximum desire spl at your listening position and scaling your amplifier power rating from there.

The thing to remember is that if your looking to go louder your power amplifier rating will go up very quickly. 6 dB is a noticeable increase in loudness. 10 dB is considered twice as loud. That would require 4 x and 10 x the amplifier power rating respectively.

A few things to note:

Turning up the Mid Lpad to full and the horn and slot to + 3 dB will increase the mid high array sensitivity to 98 dB. So your amplifier power requirement is half in that scenario. But you loose adjustment of the L pads.

Modern recordings are more dynamic than older analogue recordings. So the 6 dB headroom factor is a reasonable allowance.

High power digital amplifiers are relatively inexpensive. So you can put a 300 watt or 400 watt digital amp on the 2245H and then use your nice HIFi amplifier on the mid high frequency array. There are numerous high quality hifi amplifiers out there in the 100 watt range.

IMHO you are going to subjectively notice a high power amplifier more on those woofers.

My suggestion is use the best power amplifier or integrated amplifier you can afford on the mid high frequency array and you will be well rewarded. The mid high frequency array is analytical enough to be able to discern subtle differences in amplifiers and signal path electronics not to mention the source.

I currently use an Ortofon Black and a Purple Heart mc cartridge on my VPI Prime with a Parasound JC3 and JC2 with an AC23+ power amp rated at 160+160 watts and it’s superb. My digital Yamaha pro power amp rated at 800+800 watts is on the woofers.

There could be the odd error in my calculations. Let me know if you spot any.

Buyers Guide Comments on power amplifiers
I am not here to plug Parasound but the A23+ does have useful features such a independent level controls and balanced/unbalanced inputs on the rear. I think it’s the equal of my Pass X250.5 and more neutral sonically. If you want to hear how your recordings were recorded as intended by the producer the Parasound 23+ is your amplifier. That is what l hear when l play some re released albums. The combo of the 4345 and the Parasound 23+ brings you closer to the original recording. The Pass 250.5 is nice and refined but it’s warmth and zing are best left out if you want to experience the evolution of recordings over the last five decades.

Meaning the Parasound is very good value for money and a great match for this genre of loudspeaker.

https://www.soundstageaccess.com/index.php/equipment-reviews/980-parasound-halo-a23-plus-stereo-mono-amplifier

[markd51]

And then I'll share my opinion on such speakers as all the 4300's, 4400's, and so many other great JBL Speakers that have been made over the last 60 years.

And that's why fix what isn't broken? For all the work the designers-engineers and the end testing and adjusting, aneoic chambers, hosts of JBL critics listening, and here you smarter folks have to split the shit out of the work they did, thinking you'll break on through to the other side.

Will you?

But like earlier, and not fussing with bi-amping, tri-amping, using a mixture of who knows what Amps to get a job done, maybe just go buy yourself a good high quality Amp, be it a Stereo, an Integrated, or a pair of Monoblocks?

And I'm not talking some cheapo D class that weighs 4.5 lbs, a pair of Mac 601's, you want a very nice integrated, go for the Gryphon Diablo, Bryston 14B3, or 7B3 Monos, or there's multiple dozens more, Parasound, etc.

I'll save space, but as I touched upon, quality power will be the key to getting the best sound from JBL. Are there better speakers out there than a pair of 4345's? You bet there are. Don't ever think the 18" can go so low, and be so authorative. Dynaudio has made 6" Bass Drivers that can handle 300 watts.

And a pair of $45K-$65K pair of Dynaudios? Yeppers I've heard them, world class speakers.

[Ian Mackenzie]

Hi Moe,

Nicely put.

What l would say is that Greg Timber’s has endorsed a number of small but important changes to these systems that collectively offer real improvements. That’s simply because Jbl marketing compromised the execution of the designs.

So your argument is with Greg. When l last met Greg we were messing with Biamping and we decided to set up an original 4331 in Biamp mode. Once correctly adjusted and placed up on crates with some room correction we compared the DD67000 to the 4331.

This is the thing. We got the 4331 to sound way better than it had any right to with high quality bi amp crossover and some careful measurements and adjustments to the response. So it was a line ball comparison to the DD67000.

That my boy is not screwing with the design. We simply were getting more out of those vintage drivers by using our smarts.

What my last few posts were about was an attempt at a layman’s explanation of how much power do you need.

Time for some pancakes and maple syrup.

You all enjoy your weekend.

[markd51]

Hi Moe,

Nicely put.

What l would say is that Greg Timber’s has endorsed a number of small but important changes to these systems that collectively offer real improvements. That’s simply because Jbl marketing compromised the execution of the designs.

So your argument is with Greg. When l last met Greg we were messing with Biamping and we decided to set up an original 4331 in Biamp mode. Once correctly adjusted and placed up on crates with some room correction we compared the DD67000 to the 4331.

This is the thing. We got the 4331 to sound way better than it had any right to with high quality bi amp crossover and some careful measurements and adjustments to the response. So it was a line ball comparison to the DD67000.

That my boy is not screwing with the design. We simply were getting more out of those vintage drivers by using our smarts.

What my last few posts were about was an attempt at a layman’s explanation of how much power do you need.

Time for some pancakes and maple syrup.

You all enjoy your weekend.

I can understand that....somewhat! LOL

Here it came, charged coupled X-overs, and of course today, we have more in the way of better Caps, Inductors, and other electro parts than Carter has pills. Or do we?! LOL

I'm sure somebody out there has a design and might build me 4 Charged Coupled X-overs for my 4 L65's. I'm sure they'd lighten my bank account too.

No doubt my 4430's pale in comparison to a pair of 4345 Monitors in some aspects, but then again, maybe they have qualities that they don't too, but I'm not about to hack them to ribbons to try making them something they aren't.

Before I do something like that, I'd rather dig down, and look into other speakers, other designs. Would I be stupid to have a pair of B&W 802D3's in house, Wilson Sophias, big Magnepan's, Martin Logans, no of course not.

All of them hole great merit. Just loan me $20K, will ya?! LOL

I am aware that this is what a clean pair of 4345's will cost as well, a good $20K give or take a few cents or so. Truly a speaker that sure would be nice to see JBL re-issue, but at what cost? Probably $70K.

I remember once trying to fit a pair of different bass drivers in my Jubals. They might've been 2216? Or 2212?
Beautiful looking driver, might've fit the front baffle, had not the L-shaped Port tube been in the way interfering with the driver's huge magnet.

Those drivers were on free loan, but I brought them back. Wasn't about to take a hatchet to a very clean pair original bought pair-quad of L-65;s just for kicks. They still have their 126A's, LE5-5, and 077's stock.

[Ian Mackenzie]

Moe,

You can build up a 4345 clone for around $5,000 (estimate)

The 4430 is a very good loudspeaker.
But newer updated woofer like the 2216nd would significantly improve the midrange clarity.
Adding a Radian Be one inch driver would also improve its performance. When l get a chance l might try that....Lol

[markd51]

Moe,

You can build up a 4345 clone for around $5,000 (estimate)

The 4430 is a very good loudspeaker.
But newer updated woofer like the 2216nd would significantly improve the midrange clarity.
Adding a Radian Be one inch driver would also improve its performance. When l get a chance l might try that....Lol

I think I once posed these same questions about an upgrade to Bass Drivers in the 4430, and pin-pointed the 2216nd as a possible upgrade replacement?

I'm not up to a lot of the technical jargon such as cubic foot cab size requirements, damping-porting and whatever else required physically, but gathered that such could be a hit or miss unknown swap without further enhancements-adjustments and mods made electronically to the Crossover Networks?

Yeah, beautiful looking drivers those 2216nd's are! Look massive.

Yep, maybe one day someone will delve into such a project with hard core measurements to back up such mods and them being worthy ones and not too complicated.

[Chas]

I don’t have a definitive answer for the OP, but I do use a choice one of three pairs of monoblocks:
Mark Levinson No. 434, 125 Watts.
DIY KT120 based 100 watt tube amps.
DIY 6L6GC based 18 Watt tubes amps.

They all work just fine for me.

[markd51]

As for the wants of going bi-amp, I'm quite sure a pair of these beautiful "Hernia Makers" would be the cat's meow, and look quite lovely sitting between a pair of the majestic 4345's! The price of admission is a shocker though!

Maybe one day they'll come with a smaller brother, and a more sane price. LOL

https://www.youtube.com/watch?v=fTWjZz5Zgug

https://www.youtube.com/watch?v=GOOASnJ5D9g

For many decades, I always felt the McIntosh-JBL pairing was a match made in heaven!
I don't think too many here will dispute my claims!

[Mr. Widget]

Since I think we have pretty well answered the original topic I’ll continue this OT discussion about multi-amping vs. going with a single amp channel per speaker.

There are very good reasons to choose either route. I first biamped my system in the late ‘70s and have had many different bi, tri, and quad amped systems since. Along the way I have learned a lot. There can be very real benefits going the multi-amp route. On the other hand, tearing apart a well designed system and going multi-amp is a very easy way to spend a ton of money and sonically take a giant step backwards. You don’t need to know how many volts are required from the power supply to generate a specific power level with a given amp/speaker combination, but if you aren’t willing to do your homework, you should find a really good full range amp and use the passive network.

Nelson Pass wrote in the introduction to his XVR-1 analog active crossover owner’s manual:

Some audio products are designed for anybody who can put batteries in a flashlight. This product is not like that.

Some audio products are designed so that you don’t have to study the manual. This product is not like that, either.

Some audio products are designed so that you plug them in and you don’t have to fool around with them for a year before the system is greatly improved....

His description is specifically about his rather complicated crossover, but it holds true for going active with any active crossover.

The bottom line is that at the theoretical level a multi-amped system with very short cables between the amps and individual drivers is without a doubt the best way to go. That said, in the real world this is not always a possibility and a pair of well designed speakers with a high quality amp can also exceed your expectations.


Widget

[markd51]

Since I think we have pretty well answered the original topic I’ll continue this OT discussion about multi-amping vs. going with a single amp channel per speaker.

There are very good reasons to choose either route. I first biamped my system in the late ‘70s and have had many different bi, tri, and quad amped systems since. Along the way I have learned a lot. There can be very real benefits going the multi-amp route. On the other hand, tearing apart a well designed system and going multi-amp is a very easy way to spend a ton of money and sonically take a giant step backwards. You don’t need to know how many volts are required from the power supply to generate a specific power level with a given amp/speaker combination, but if you aren’t willing to do your homework, you should find a really good full range amp and use the passive network.

Nelson Pass wrote in the introduction to his XVR-1 analog active crossover owner’s manual:

Some audio products are designed for anybody who can put batteries in a flashlight. This product is not like that.

Some audio products are designed so that you don’t have to study the manual. This product is not like that, either.

Some audio products are designed so that you plug them in and you don’t have to fool around with them for a year before the system is greatly improved....

His description is specifically about his rather complicated crossover, but it holds true for going active with any active crossover.

The bottom line is that at the theoretical level a multi-amped system with very short cables between the amps and individual drivers is without a doubt the best way to go. That said, in the real world this is not always a possibility and a pair of well designed speakers with a high quality amp can also exceed your expectations.


Widget


What you say makes great logical sense, and I basically linked such a Milionaire's state of the art system for mostly giggles and amusement purposes only.

A true reference system within more sane end costs could be put together-accomplished for a lot less money, take up a lot less real estate, and a lot less back strain also. This then leaves money to be used elsewhere in a system.

Which as many would say, such is only as good as its weakest links-components.

Let's say within the McIntosh Line-Up, and going single and simpler Stereo Amps, or Monos driving the 4345 Full Range. Such could be a McIntosh SS MC-452, with a respective 450 wpc on tap, various Monoblock Amps they have made, and if tubes are your preference, and you're not looking to wake the dead, a simple MC-275 could do the trick?
Or their more massive and powerful MC-2301 Tube Monoblocks. Or older MC-501 Monoblocks.

This list could be endless, and I'd probably be correct that running full range with a very good quality Amp and PreAmp just might net much greater sonic gains and pleasure as you touch upon rather than running the gamut with separate and an incompatible mix of various "dopey Musician's Friend" Amps, external crossovers, wiring, and all sorts of complications, which might defeat the end goals, and be a cluster you know what mess that in the end got you going backwards.

I have zero doubt, that my "lowly" bought new pair of Bryston 7BSST2 Monoblocks, while not looking very imposing like some Amps, and like the ones I link to above, would very pleasingly drive a pair of perfect condition 4345's with aplomb, just like they do with my pair of 4430's.

When I first got those Amps, they were a major disappointment, coming from McIntosh Amplification. I sure didn't know that those new Amps would need a good 200 hours of break-in time to strut their stuff. They were quite thin, lean and cold. Like I almost took the bass drivers out of the 4430's.

No, I won't ever claim Bryston is the best Amp of all, but I will say they have worked out much better than very well, control those 2235H Bass Drivers with clean, tight uncolored definition, and non-muddied response, the mids and highs have excellent uncolored clarity-precision, and focus, these are not warm amps, but IMO very accurate and very quiet-clean amps. An with an unbeatable 20 year warrantee.

No, there's no big blue eye candy meters like McIntosh, and akin to like what Ashley Roachclip once said on a Cheech and Chong Record-Acapulco Gold Commercial. "Hey Man, whatayou want, Good Grammer, or Good Taste"? LOL

Same holds true with Audio gear, what do you want, good looks, or good sound?

I've been slowly but surely working my system up piecemeal, state of art cabling here and there, and soon I think a dedicated line service and a nice Shunyata Power Conditioner for source components will be in my future.

I'm now running a $900 Phono Cable to phono stage and a $900 Cable from Phono Stage to PreAmp, both pure OCC Silver, compliments of Audio Sensibility in CA.

[Ian Mackenzie]

One of the reasons people can come un stuck with a passive to active crossover conversion is the assumption the passive network is textbook design. In a quality designed passive loudspeaker the crossover filters are custom calibrated to the specific drivers and placement on the baffle.

The engineer then voices the crossover in a real room listening situation and makes further adjustments. Sometimes this will involve a panel of golden ear people to advise on system at various stages of the final iteration.

So plugging in an active crossover with only text book crossover settings is going to be a step backwards.

So how do you go about accurately setting up an active version of a loudspeaker?

That will be the topic of a series of Webinars l will be hosting in a few months time.

[Robh3606]

So how do you go about accurately setting up an active version of a loudspeaker?

All you have to do is match the voltage drives to the individual drivers. So you measure the output of the passive crossover, create a target curve from that measurement and set-up an active curve to match it. As long as you can get a good measurement of the curve you should be good to go.

Rob:)

[speakerdave]

All you have to do is match the voltage drives to the individual drivers. So you measure the output of the passive crossover, create a target curve from that measurement and set-up an active curve to match it. As long as you can get a good measurement of the curve you should be good to go.

Rob:)

The voltage drive of the passive crossover is calibrated into an eight ohm load. What load is used in setting the active crossover? Do you drive through an amp into an eight ohm load?

[Ian Mackenzie]

All you have to do is match the voltage drives to the individual drivers. So you measure the output of the passive crossover, create a target curve from that measurement and set-up an active curve to match it. As long as you can get a good measurement of the curve you should be good to go.

Rob:)

Hi Rob,

That’s the basics but doing it by Joe Citizen is a leap of faith. At least the was the view of Nelson Pass and Greg Timber’s when we met to talk about an active crossover for specific loudspeakers,

Greg was quite specific on how to go about it.

[Ian Mackenzie]

The voltage drive of the passive crossover is calibrated into an eight ohm load. What load is used in setting the active crossover? Do you drive through an amp into an eight ohm load?

Come along to the webinar

[Robh3606]

The voltage drive of the passive crossover is calibrated into an eight ohm load. What load is used in setting the active crossover? Do you drive through an amp into an eight ohm load?


Take a look here. Curious to hear what Greg has to say about how to do it.

Rob :)

http://www.audioheritage.org/vbulletin/showthread.php?23763-Bi-amping-the-JBL-Model-1400-Array

[toddalin]

Rock Concerts, I've been to quite a few. An ELP concert with the introduction of their Brain Salad Surgery release will make 20 pairs of those 4345 Speakers sound like a 9V Battery Pocket Transistor Radio. Ask me how I know!

https://www.youtube.com/watch?v=wz6Mj8cROJw


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? ;)

[Ian Mackenzie]

On the subject of voltage drives there are several challenges

1. Accurate data collection
2. Curve fitting the active voltage drive
3. Design of the active filter

It might look straight forward but it’s not once the effect of the passive crossover is fully investigated.
A passive crossover interacts with the drivers as they are electro mechanical devices When the loudspeaker engineer/ designer finalises the passive loudspeaker design these interactions are accounted for.

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.

This is where the skill of a engineer is required to interpret and make the correct decisions in the design of the active system.

Typically the passive crossover has some problems and you don’t want to make the mistake of copying those problems. But then you need to address what changes need to be made.

We went through that exercise with the DD65000, DD67000, DD66000.

The challenges are unique to each loudspeaker such as the 4345, 4343 and the 4344mk11.

As mentioned this is a great topic for a webinar which l will look at a bit later in the year.

[speakerdave]

I think you mean one translates a curve from one system to another, guided by reference to new raw data, but not sure. There was a time, after a year or so of reading literary theory, I thought I would eventually be able to penetrate anyone's patois, if I wanted to bad enough, but no. I still hold out hope that I will eventually understand Don Lancaster and Douglas Self, but this is kind of like reading Helena Petrovna Blavatsky.

As Giskard, Lancer, 4313B said more than once: "It's beyond the scope of these forums." Or maybe just me. But still, it's remarkable that you would take a shot at it.

[Ian Mackenzie]

It’s a case of what you don’t know you don’t know.

There is a difference between an audio amateur (a dangerous one) and a world class engineer like Greg Timber’s. I trust you respect that.

[speakerdave]

It’s a case of what you don’t know you don’t know.

There is a difference between an audio amateur (a dangerous one) and a world class engineer like Greg Timber’s. I trust you respect that.


Oh yeah. That's certain. If I could buy his work, I would.

[Dr.db]

Hi Ian,

thanks a lot for your very detailed answers, really appreciate the time you put into it!



The approach taken at the time was a 300 hertz crossover point was a 50/50 split in the amplifier power rating and a 800 hertz crossover point was a 75/25 in the power rating.


This answers my question to 100%, thanks!
Using 300hz as a crossover it is an even power-distribution on both sides. The difference in the required power is only caused by a difference in sensitivity.
Your example of the 800hz crossover and 75/25 power split is what I had expected as well for the 300hz crossover. But 300hz seems to be to energy-intensive, great you brought this example up!

[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.