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Author Topic: Which I-Tech Amps For Sub Duty  (Read 2399 times)

Mario Pollio

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Which I-Tech Amps For Sub Duty
« on: February 03, 2020, 02:11:20 pm »

I just purchased a pair of JBL 5628 subwoofers as part of a large home theater set up that uses JBL M2's coupled with Crown I-tech 5000HD's. My question is, which I-tech amp would you use to power the 5628's to get the most out of them? Some have suggest an I-tech 12000HD to power them, which would give each sub 4,500 watts into the 4 ohm load. I'm sure that would work, but the subs are capable of handling a lot more power than that. What other I-tech/JBL 5628 configuration could I do with these subs? Is it wise to run a single I-tech bridged into each sub, or is that demanding too much of the amp (bridged into a 4 ohm load)? How does the I-tech 4x3500HD do for sub duty?

I know there are a lot of other amp options to power these, I just want to stick with the I-tech family of amps since that's what I have already with my M2's. I like the way Audio Architect works integrated with the amps, I'd like to retain that for my subs.

Here's a link to the subs I ordered

https://jblpro.com/en-US/products/5628
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Tracy Garner

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Re: Which I-Tech Amps For Sub Duty
« Reply #1 on: February 03, 2020, 03:23:44 pm »

I just purchased a pair of JBL 5628 subwoofers as part of a large home theater set up that uses JBL M2's coupled with Crown I-tech 5000HD's. My question is, which I-tech amp would you use to power the 5628's to get the most out of them? Some have suggest an I-tech 12000HD to power them, which would give each sub 4,500 watts into the 4 ohm load. I'm sure that would work, but the subs are capable of handling a lot more power than that. What other I-tech/JBL 5628 configuration could I do with these subs? Is it wise to run a single I-tech bridged into each sub, or is that demanding too much of the amp (bridged into a 4 ohm load)? How does the I-tech 4x3500HD do for sub duty?

I know there are a lot of other amp options to power these, I just want to stick with the I-tech family of amps since that's what I have already with my M2's. I like the way Audio Architect works integrated with the amps, I'd like to retain that for my subs.

Here's a link to the subs I ordered

https://jblpro.com/en-US/products/5628


Find an iTech 8000 and run it discrete. 2x2100 @8ohm and enjoy.

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Mario Pollio

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Re: Which I-Tech Amps For Sub Duty
« Reply #2 on: February 03, 2020, 03:40:39 pm »


Find an iTech 8000 and run it discrete. 2x2100 @8ohm and enjoy.

You think an 8000 would be better than a 12000?
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Paul G. OBrien

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Re: Which I-Tech Amps For Sub Duty
« Reply #3 on: February 03, 2020, 04:07:04 pm »

Something doesn't add up, the blurb on speakers website quotes ridiculous power handling figures... like something you would expect from a car audio manufacturer. The actual spec sheet has more sane numbers.. 1000w per driver long term but even that is with an AES test signal which means continuous sine wave power would be 500w rms. The drivers will of course take more power on short duration peaks but not at all frequencies, this being a ported box excursion maximum occurs right in the middle of the pass band around 55-60hz. So Tracy's suggestion is a good one that won't leave much on the table, powering one box per channel on a iT12k would allow roughly 3dB more headroom on high crest factor material only but also makes the system capable of instantly destroying the drivers without some pretty clever limiting in place, but even if the drivers don't die I'm not confident the building would survive.. you do realize you are talking about a pair of boxes capable of generating up to 140dB at sub bass frequencies.
« Last Edit: February 03, 2020, 04:09:29 pm by Paul G. OBrien »
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David Sturzenbecher

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Re: Which I-Tech Amps For Sub Duty
« Reply #4 on: February 03, 2020, 04:22:00 pm »

You think an 8000 would be better than a 12000?

Power wise these are the exact same amplifier.  The 12000 just has upgraded processing...with better limiting.
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Tim McCulloch

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Re: Which I-Tech Amps For Sub Duty
« Reply #5 on: February 03, 2020, 04:28:50 pm »

JBL does real long term power handling tests - if you ever get a tour of JBL in Northridge, CA one the brief stops will be the "soundproof" testing room where they perform these tests.  They extrapolate peak numbers from the results of that testing...

You don't need to throw thousands of Watts at loudspeakers.  Seriously, I think the urban myth was started by amplifier manufacturers (like the transducer manufacturers LOVE line arrays..).

This is the driver that JBL also used in the 4880a subwoofer from the VerTec line.

edit PS... after reading a bit of Josh Ricci's writings regarding amount of power needed for ELF, I can see why larger amps might be perceived as beneficial if the ELF lasts longer than it takes to reach the power sag of the amplifier.  Since I don't know the program content you want these for, you *may* benefit from a larger amp, but my experience is that we run out of excursion before we run out of amplifier.
« Last Edit: February 03, 2020, 04:38:53 pm by Tim McCulloch »
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"Practicing an art, no matter how well or badly, is a way to make your soul grow, for heaven's sake. Sing in the shower. Dance to the radio. Tell stories. Write a poem to a friend, even a lousy poem. Do it as well as you possible can. You will get an enormous reward. You will have created something."  - Kurt Vonnegut

Steve-White

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Re: Which I-Tech Amps For Sub Duty
« Reply #6 on: February 03, 2020, 04:56:20 pm »

I am setup to drive pairs of 2269H in ported enclosures and do it with Crowm MA5000iís.

An iTech 8000 for HT duty should rattle the fillings out of your teeth at 24 hz.

I have a pair of MD7 enclosures in my den.  Got a great deal on them and was like king for 2269Hís, so I picked up 4 of them and pulled the 2269Hís for single enclosures.

I kept 2 of the MD7 enclosures & gave the other 2 to a pal.  Mine are loaded with JBL 2245H 18ís.  My buddy put McCauley 6174ís in his pair.

Vintage Phase Linear Dual-500 on mine in the den and it gets better uncomfortable real easy.  Turned up, not full power - about -6db and I can only tolerate about 4 minutes before turning it down.  Thatís clean thundering bottom end - itís overwhelming - no brag there either.

No disrespect meant here - but that system is bigger than mine and whatís in my den is overkill and really dangerous if misused.  4 x 2269Hís powered up will destroy a 300 seat night club with band or DJ.

Have fun with it - come back once itís all setup and tested and you have unleashed it.

In a good way - I donít think you know what you have - prepare to be blown away!
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Mario Pollio

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Re: Which I-Tech Amps For Sub Duty
« Reply #7 on: February 03, 2020, 06:42:54 pm »

Something doesn't add up, the blurb on speakers website quotes ridiculous power handling figures... like something you would expect from a car audio manufacturer. The actual spec sheet has more sane numbers.. 1000w per driver long term but even that is with an AES test signal which means continuous sine wave power would be 500w rms. The drivers will of course take more power on short duration peaks but not at all frequencies, this being a ported box excursion maximum occurs right in the middle of the pass band around 55-60hz. So Tracy's suggestion is a good one that won't leave much on the table, powering one box per channel on a iT12k would allow roughly 3dB more headroom on high crest factor material only but also makes the system capable of instantly destroying the drivers without some pretty clever limiting in place, but even if the drivers don't die I'm not confident the building would survive.. you do realize you are talking about a pair of boxes capable of generating up to 140dB at sub bass frequencies.

The different power ratings were obtained with different levels of "torture testing." The higher power rating numbers were tested for 2 hours. Those lower numbers you quoted are for 100 hours of torture testing. From my understanding, it's pretty rigorous stuff these drivers are put through. I don't think an I-tech 12000HD would destroy 4 2269h drivers unless you are intentionally trying to blow them. Normal content shouldn't harm the drivers. Our ears, that's a different story. And yes, I do realize that very well. I don't think I'll ever feel the need for "more bass" with these things. At full tilt, I to am worried about the structural integrity of my house. Isn't it exciting  ;D :P

Power wise these are the exact same amplifier.  The 12000 just has upgraded processing...with better limiting.

Interesting, I didn't know that. So the benefit of an 8000 over a 12000HD would be price, I'm assuming.


JBL does real long term power handling tests - if you ever get a tour of JBL in Northridge, CA one the brief stops will be the "soundproof" testing room where they perform these tests.  They extrapolate peak numbers from the results of that testing...

You don't need to throw thousands of Watts at loudspeakers.  Seriously, I think the urban myth was started by amplifier manufacturers (like the transducer manufacturers LOVE line arrays..).

This is the driver that JBL also used in the 4880a subwoofer from the VerTec line.

edit PS... after reading a bit of Josh Ricci's writings regarding amount of power needed for ELF, I can see why larger amps might be perceived as beneficial if the ELF lasts longer than it takes to reach the power sag of the amplifier.  Since I don't know the program content you want these for, you *may* benefit from a larger amp, but my experience is that we run out of excursion before we run out of amplifier.

Yes, I've seen footage of that "soundproof" room. Cool stuff to say the least. Yup, this driver is used in there G28 and S28 array subwoofers as well. Very serious stuff. The D2 drivers in the M2's are also used in their VTX arrays.

I just want to match the right amp to the sub to get the most out of them. Not like I will ever need them to their maximum potential, but I like lots of headroom. It's nice to have lots of effortless SPL while the speakers and amps are just coasting.

I am setup to drive pairs of 2269H in ported enclosures and do it with Crowm MA5000iís.

An iTech 8000 for HT duty should rattle the fillings out of your teeth at 24 hz.

I have a pair of MD7 enclosures in my den.  Got a great deal on them and was like king for 2269Hís, so I picked up 4 of them and pulled the 2269Hís for single enclosures.

I kept 2 of the MD7 enclosures & gave the other 2 to a pal.  Mine are loaded with JBL 2245H 18ís.  My buddy put McCauley 6174ís in his pair.

Vintage Phase Linear Dual-500 on mine in the den and it gets better uncomfortable real easy.  Turned up, not full power - about -6db and I can only tolerate about 4 minutes before turning it down.  Thatís clean thundering bottom end - itís overwhelming - no brag there either.

No disrespect meant here - but that system is bigger than mine and whatís in my den is overkill and really dangerous if misused.  4 x 2269Hís powered up will destroy a 300 seat night club with band or DJ.

Have fun with it - come back once itís all setup and tested and you have unleashed it.

In a good way - I donít think you know what you have - prepare to be blown away!

I have a pretty good idea of what I have, but have yet to experience it first hand in this situation. My original plan was to get 2 SUB18's (single 2269h driver per enclosure) but the 5628's were actually cheaper! So it was a no brainer. Here's the room these monsters will be going in. I just have to be careful not to put anyone into cardiac arrest with these things.
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Tim McCulloch

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Re: Which I-Tech Amps For Sub Duty
« Reply #8 on: February 03, 2020, 07:34:35 pm »

One of the things JBL doesn't directly document is power compression, but Josh Ricci considers 4-5dB to be acceptable.  I'm a bit more sanguine.  If I'm turning almost 4x power into heat and not cone movement, it doesn't accomplish anything.

I did some testing for my employer (and hence won't be discussing specific numbers) and I encourage you to do so.  Simply that a voice coil will survive is not indicative that volts & current are being turned into *linear* amounts of SPL.  This is one of the reasons I say we don't need megawatts of power unless we're trying to warm the room with voice coil heat.
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"Practicing an art, no matter how well or badly, is a way to make your soul grow, for heaven's sake. Sing in the shower. Dance to the radio. Tell stories. Write a poem to a friend, even a lousy poem. Do it as well as you possible can. You will get an enormous reward. You will have created something."  - Kurt Vonnegut

Mario Pollio

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Re: Which I-Tech Amps For Sub Duty
« Reply #9 on: February 03, 2020, 07:46:56 pm »

One of the things JBL doesn't directly document is power compression, but Josh Ricci considers 4-5dB to be acceptable.  I'm a bit more sanguine.  If I'm turning almost 4x power into heat and not cone movement, it doesn't accomplish anything.

I did some testing for my employer (and hence won't be discussing specific numbers) and I encourage you to do so.  Simply that a voice coil will survive is not indicative that volts & current are being turned into *linear* amounts of SPL.  This is one of the reasons I say we don't need megawatts of power unless we're trying to warm the room with voice coil heat.

Are the power ratings JBL provides the maximum power the driver will take before it blows, or is it considered a maximum amount of power the driver can take while not power compressing gobs of power and farting away in the process? I know the driver is very hard to blow due to over excursion, as one of the effects of differential drive.
 
This is a quote from data-bass that tested the 2269h driver.  "Additionally a magnetic braking effect can be induced when one of the coils enters the other coils gap and is repelled by an opposing magnetic force. This does not sound good when it happens. Even though no parts are making physical contact it is a form of clipping of the signal and is quite audible. However it does produce a driver that is immune to mechanical over excursion"

So basically, the amount of power that the driver can take before power compression and the amount it can take before actually blowing are probably vastly different.
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Re: Which I-Tech Amps For Sub Duty
¬ę Reply #9 on: February 03, 2020, 07:46:56 pm ¬Ľ


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