4367 and two Crown I-Tech5000HD

[Silvanik]

I need your help, in your opinion, what if I go this way, bypass the original internal 4367 xover and go straight to drivers with two dedicated Crown I-Tech5000HD (with electronic xover properly set) but not using the kind of D2430K protection implemented in M2? I mean, at home listening level I expect to have more clarity and low risk to burn the mid-high driver, substantially more sound quality.Am I wrong?

[Riley Casey]

Direct connection of the very low output impedance of the amplifier to the voice coils will allow the best control of the speakers. The I Tech has output relay load protection that is far more robust than any passive network for DC faults IF you have confidence that you won't introduce any out of band signals ie frequencies below the operating range of the driver. Setting the limiters appropriately in the DSP along with the crossover characteristics would protect against 'accidents' given the large power mismatch between the iTech and the rated power capacity of the speaker. Absent any factory DSP presets this would require a significant amount of acoustic measurement & testing to achieve best results.

[Silvanik]

For the listening setup so far, I made these stands, solid wood and real carbon fiber, height 17cm for optimal alignment according to ears height when sitting. It has to be checked if this height is still good when the 4367's are driven with two Crown and no passive xover.

[Silvanik]

Direct connection of the very low output impedance of the amplifier to the voice coils will allow the best control of the speakers. The I Tech has output relay load protection that is far more robust than any passive network for DC faults IF you have confidence that you won't introduce any out of band signals ie frequencies below the operating range of the driver. Setting the limiters appropriately in the DSP along with the crossover characteristics would protect against 'accidents' given the large power mismatch between the iTech and the rated power capacity of the speaker. Absent any factory DSP presets this would require a significant amount of acoustic measurement & testing to achieve best results.

Of course is my intention to put max attention to the best possible setup of Crown's concerning limiters, xover points and listening volume. Talking about xover setup, what is your suggestion for the specific use with the 4367's? I mean, frequencies, slope and so on. Would you replicate the passive value, 700Hz? And the last, what do you think using the JBL DSP preset available for M2? Should it works with 4367 or is better to avoid it?Many thanks

[rusty jefferson]

Wouldn't want to deter you from what you're proposing but if they are lacking clarity in your living room you may want to look at other parts of your system being a possible source of the issue. The time I spent with a pair in a modest system, I thought they had excellent midrange and treble clarity without even a hint of roughness. They shouldn't have the polite smoothness the 1400 Array have. Also, unless you really know how to properly measure them and more importantly how to interpret those measurements, you're unlikely to improve upon the speakers as they are, not to mention the cost of iTech amplifier(s). If what you're after is the M2 experience......:-)

[Mr. Widget]

And the last, what do you think using the JBL DSP preset available for M2? Should it works with 4367 or is better to avoid it?Many thanks

Using the M2 DSP settings for the 4367 will not be ideal. The speakers are similar, but not identical. The woofers and horns are both different so subtle or perhaps not so subtle changes will be required.


Widget

[sebackman]

+1

They are very different. I have had both. You cannot use the M2 filter settings for the 4367.

The voltage drive in the 4367 white paper will give you some guiding, but remember that passive filers are dynamic as the impedance of the driver changes over the frequency and changes the filter, while DSP normally does not.

I don't think you can take the voltage drive of the 4367 passive filter and create an active copy and achieve the same result. I probably spent 100-200 hours on the DSP setup with my 4367M, albeit using a large format driver instead of the original D2. You will need to create a new active filter for your setup.

The results are very rewarding, but unless you are familiar with acoustics and measurements I would not tamper with the original passive filters. The JBL engineers knew what they were doing.

Have nice weekend
//Rob

[Silvanik]

Wouldn't want to deter you from what you're proposing but if they are lacking clarity in your living room you may want to look at other parts of your system being a possible source of the issue. The time I spent with a pair in a modest system, I thought they had excellent midrange and treble clarity without even a hint of roughness. They shouldn't have the polite smoothness the 1400 Array have. Also, unless you really know how to properly measure them and more importantly how to interpret those measurements, you're unlikely to improve upon the speakers as they are, not to mention the cost of iTech amplifier(s). If what you're after is the M2 experience......:-)

Actually I don't feel any lack of clarity, my idea is only to push 4367's performance to the max just because I already own a pair of I-Tech5000Hd (to be honest I also have one I-Tech9000HD...), thus was thinking about the best way to get it.

[Silvanik]

Using the M2 DSP settings for the 4367 will not be ideal. The speakers are similar, but not identical. The woofers and horns are both different so subtle or perhaps not so subtle changes will be required.Widget

May be you are right, it's better to tailor specific xover and DSP setup for 4367's, I'm used to REW to take measurement even if it's not so easy to get in full control with room acoustics , for sure I need some help from professional but this should lead to best results.

[Silvanik]

+1They are very different. I have had both. You cannot use the M2 filter settings for the 4367.The voltage drive in the 4367 white paper will give you some guiding, but remember that passive filers are dynamic as the impedance of the driver changes over the frequency and changes the filter, while DSP normally does not. I don't think you can take the voltage drive of the 4367 passive filter and create an active copy and achieve the same result. I probably spent 100-200 hours on the DSP setup with my 4367M, albeit using a large format driver instead of the original D2. You will need to create a new active filter for your setup.The results are very rewarding, but unless you are familiar with acoustics and measurements I would not tamper with the original passive filters. The JBL engineers knew what they were doing.Have nice weekend//Rob

I get your point. Do you think it's a big risk to go fully active? A cross point at 700Hz should be not close to the result with passive filtering if not better due to the absence of phase and impedance shift that passive xover for sure introduce?A nice and well sounding weekend also to you!

[pos]

I don't have first hand experience with the I-Tech amps, but I doubt connecting a D2430K directly will go smoothly.
There is a reason why JBL includes a passive network (-10dB pad and 1st order 1kHz HP filter) in the M2, despite the added costs, and despite the ample DSP capabilities of the amps.
Two reasons in fact: mitigate risks for the compression driver (including, among many others, human error), and avoid noticeable hiss at the listening position...

If you want to experiment your safest bet might be to keep the existing passive network for the compression driver, and go full active on the woofer side.
But even that requires a lot of work and measurements to get right (ie comparable to the passive solution).

[Silvanik]

I don't have first hand experience with the I-Tech amps, but I doubt connecting a D2430K directly will go smoothly.There is a reason why JBL includes a passive network (-10dB pad and 1st order 1kHz HP filter) in the M2, despite the added costs, and despite the ample DSP capabilities of the amps.Two reasons in fact: mitigate risks for the compression driver (including, among many others, human error), and avoid noticeable hiss at the listening position...If you want to experiment your safest bet might be to keep the existing passive network for the compression driver, and go full active on the woofer side.But even that requires a lot of work and measurements to get right (ie comparable to the passive solution).

I am aware of needed job to get a good balance out of the totally new driving mode but at same time convinced that any passive xover always limit the full potential of any sound system. Of course the full active solution is much more expensive thus not easy for a manufacturer to propose it to the market, but I already own a pair of Crown I-Tech5000HD, this is why, if is not there a real big cons (which in case I would understand) I'm very attracted to give this approach a try.

[Riley Casey]

If you know the transfer characteristics of the existing passive crossovers you can certainly duplicate those in the DSP as a starting point. If you have DSP settings for a similar model with similar drivers you can use those as a starting point. You may see a pattern here. This is going to be the beginning of an adventure not a plug and play solution. On the other hand passive networks have inherent limitations that active DSP crossovers and high powered low output impedance amplifiers don't. If you don't know with certitude the characteristics of the passive networks you can measure those with your transfer function software of choice by tapping the signal at the driver terminals thru a resistive pad to attenuate and isolate the signal arriving at your audio interface. If you don't have a lot of experience in speaker testing & design currently you will when you're done.

Of course is my intention to put max attention to the best possible setup of Crown's concerning limiters, xover points and listening volume. Talking about xover setup, what is your suggestion for the specific use with the 4367's? I mean, frequencies, slope and so on. Would you replicate the passive value, 700Hz? And the last, what do you think using the JBL DSP preset available for M2? Should it works with 4367 or is better to avoid it?Many thanks

[Robh3606]

You have a well engineered speaker. I would leave it be the chances of you improving it are limited at best. Don't fix what's not broken.

Rob

[Earl K]

Hi Silvanik,

My advice ( if you want to go 100% active-DSP ) would be to contact Harman International > get a recommendation from them for a qualified Synthesis technician for your area and then contract that person to design for you the crossover topology and DSP settings for your iTech-HD amps ( to drive your 4367 speakers ).

Ignoring that advice, your two amps can easily be used to drive the internal passive crossovers in a Passive BiAmp mode. The improvement here will be incremental, but should still be audible.

The next level of improvement would be to go with a pretty straightforward active crossover arrangement as the 4367's lowpass ( using the built-in DSP//crossover capabilities of your iTech amps > of course, you need to disconnect the existing LowPass for the woofer before hooking up the LF amplifier, as well as, removing the connecting buss-bars on the back of the box that connect the Hi + Low crossover sections ).
- Maintain the HF section as a Passive Biamp arrangement ( with a separate amp driving the builtin HiPass crossover )
- The audible improvement here should be substantial ( if done correctly ) by removing the power-robbing passive parts between the amp and the woofer.
- IME, this arrangement offers the best sonics of all 3 possibilities ( I find that generally, compression drivers benefit from the use of passive components > in the home environment ) .

I think your problem here in this conversation, is that "you-don't-know-what-you-don't-know" ( IOW, you're drastically under-estimating the amount of work and knowledge that's required to get good results ).
- Others have tried to gently tell you just how out of whack your expectations are, so maybe it's starting to sink in.

Here's a ( quite basic ) first pass at creating a usable LowPass for the 4367 ( 4 different bits of software were involved just to get to this result > which ate up 3-4 hours of my time, mostly in the curve-matching exercise and learning some new software > [ "AudioArchitect" ] ).
- Yes, to achieve the "acoustic crossover of @ 700hz", does require an "electronic crossover" to be set to @ 500hz .

I've also ( zipped ) this configuration file ( called a ".device" file ) for this lowpass and have included it here.
- Unzip it, load this file onto a memory stick > then load that file into your amp(s) dsp section > all assuming that those iTechs can accept USB memory sticks and this sort of file .