I have a Crown XLS1000 and a XLS1500 for use in an organ system. These power big speakers for the pedals. Some of the lowest organ stops go down to around 16 Hertz.
I've built speakers that will reproduce the lowest sounds. BUT....
Contacted Crown. The XLS series of amps have a built-in rolloff of 12 dB per octave below 20 Hertz. Presumably this is to reduce rumble and other noises common to Hi Fi or PA systems.
I've been advised that most amps have this limitation.
Does anyone know of an amp series that doesn't have this "limitation" built-into their design? Such an amp might help us get better SPL in our speakers for those last four or five lowest notes.
Bach On
I've built speakers that will reproduce the lowest sounds. BUT....
Contacted Crown. The XLS series of amps have a built-in rolloff of 12 dB per octave below 20 Hertz. Presumably this is to reduce rumble and other noises common to Hi Fi or PA systems.
I've been advised that most amps have this limitation.
Does anyone know of an amp series that doesn't have this "limitation" built-into their design? Such an amp might help us get better SPL in our speakers for those last four or five lowest notes.
Bach On
Bach On,
Seems that a HP at 20 Hz is pretty common even on the more expensive PA amps. Since your amp's rolloff is only 12 dB per octave, the filter would only be cutting about 5-8 dB at 16 Hz, you can EQ that back in, or set the level louder on your organ's low notes. In combination with a narrow band boost around 16 Hz, the rolloff the amp has built in will become steeper, a good feature for your BR, keeping excursion in check below Fb.
You also could check on the AVS forum and see what they are using for amplification, many there are posting response down to the single digits.
http://www.avsforum.com/forum/155-d...9-class-d-amps-flat-subsonic-performance.html
Art
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Eq won't help much at high power levels. You'll need an amp that has the power supply
to support such low frequencies, which means large capacitance for linear supplies,
or else a switching supply instead.
Regardless of the small signal response, most amplifiers with linear supplies will be down about 2dB at 20 Hz compared to 100 Hz at rated load impedance unless they were overdesigned intentionally for hi-fi use. To minimize this delta, use an amp rated for 2 ohms and run it at 8. That drops the low end pole frequency created by the load and the supply caps down by a factor of 4. The real (dirty little secret) reason most amps intentionally roll off the low end at 20 or 40 with the input coupling caps (or other filtering) is so that the input pole frequency dominates. If it doesn't, it won't clip cleanly at low frequency.
Amps with switching supplies are a mixed bag. Some are better than others at low frequency. The Crown XTi1000 was notorious for sucking at 20 Hz. The XLS's seem to be better, and the iNukes do surprisingly well.
Amps with switching supplies are a mixed bag. Some are better than others at low frequency. The Crown XTi1000 was notorious for sucking at 20 Hz. The XLS's seem to be better, and the iNukes do surprisingly well.
I believe the Cerwin Vega CV2800 / CV5000 are rated -3dB @ 5Hz, or if you really want to hit the lowest notes, I believe the Crown M600 and its variously named identical alternatives are good for DC... (Josh Ricci has posted a response graph of the latter somewhere on Data-Bass forum.)
I think BossoBass is offering his A14K amps that roll off at 2Hz as well, also posted on DB forum, and one of the guys on there has posted a 'tweak' to the iNuke amps that removes the rolloff they have, but it's a soldering iron job.
Notnyt on AVS has a thread where he was testing amps and their responses but I've not checked in for ages so am not sure what he's tested now. I am hoping the CV5000 will get done at some poiint, purely out of self-interest! lol
I think BossoBass is offering his A14K amps that roll off at 2Hz as well, also posted on DB forum, and one of the guys on there has posted a 'tweak' to the iNuke amps that removes the rolloff they have, but it's a soldering iron job.
Notnyt on AVS has a thread where he was testing amps and their responses but I've not checked in for ages so am not sure what he's tested now. I am hoping the CV5000 will get done at some poiint, purely out of self-interest! lol
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Allen and Rodgers are two well known organ brands. They both made amps for their instruments. But the amps were not really powerful. They would produce sounds for that lowest octave without any significant rolloff.
The problem is that most modern speakers seem to want more power.
Bach On
The problem is that most modern speakers seem to want more power.
Bach On
I've posted in your threads before but inukes have proven to handle infrasonics well.
This is a bench test that shows a drop of only about 1db by 10hz.
How to extend the high pass filter below 20hz in DCX2496 - AVS Forum | Home Theater Discussions And Reviews
You can also read here about how to use filters cleverly to implement a sub-20hz HPF despite the DSP not allowing crossovers below 20 with the inukes.
This is a bench test that shows a drop of only about 1db by 10hz.
How to extend the high pass filter below 20hz in DCX2496 - AVS Forum | Home Theater Discussions And Reviews
You can also read here about how to use filters cleverly to implement a sub-20hz HPF despite the DSP not allowing crossovers below 20 with the inukes.
The Old Macro-Techs (Look at my avatar) will have no problem playing 16 Hz as their -3 dB points are in the single digits.
There are plenty of amps out there that are "3dB down" in the single digits, yet CLIP at 60% of the power at 20 Hz as they do at 1 KHz. Crown macrotechs are a little better than that - probably more like 90% - but it's still less.
Actually, I benched my Crowns and they will deliver their rated specs down to 10 Hz. So I can assure anyone that is looking for amps to deliver power below 20 Hz, the old Crowns will do it. If you have the amperage, to feed the almplifier properly, the old Crowns will do it.
For the little amps Bach On is using at the moment an old MA 2400 will get the job done.
I think some of the QSC models have a 5 Hz filter. (i'm not thinking about the switchable filters, but the inbuild infrasonic)
Will deliver rated specs at 10 Hz. But they will still put out a bit more a 1 KHz. Don't tray this with a new Crown, however.
I own the old Macro-Tech and Powerbase amplifiers so those are the ones I've tested.
You should get anywhere from 860 - 825 watts from an MA 2400 unclipped signal from 10 Hz - 5 Hz under a 4 ohm load stereo mode. The Old Macro-Tech amplifiers are 1 ohm stable in Parallel-mono. You can expect 1720 - 1650 watts under a 2-ohm load (Parallel Mono) or 1720 - 1650 watts under an 8-ohm Bridged Mono from an MA 2400 from 10 Hz - 5 Hz. You do not need anything bigger than a MA 2400
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I was given the information on the newer Crown XLS series. That came from Tech Support at Crown. They do have substantial roll-off below 20 Hz.
Is the MA 2400 solid state, tube, pixie dust, or what? I notice that they are much heavier. Do they tend to hold up? Are they prone to over heating.
I'd like to buy ONE for running our big bass boxes. Looks like used would be our only option. I've seen $450 to $797 on eBay today. But I'll keep looking around.
Anyway, thanks for the lead.
Since the MA2400 doesn't have any crossover circuitry like the XLS series, I'd need to purchase some sort of crossover for each speaker.
Any other specific models others can recommend? I'd love to find a new model that doesn't have this roll-off.
Bach On
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The Crown Macro-Tech Series (Research Crown Macro-Tech Series on Crown’s Website) was a touring amplifier. It was designed for the professional touring market. It requires power to drive so, if you cannot supply a minimum of 20 amperes in order for an MA 2400 to operate properly, this amplifier is not for you. It is possibly the only amplifier available on the used market that is Class AB that will offer 2000 watts of continuous power. Amplifiers that offer 2000 watts and greater are usually class H or more so class D in this day in age.
Crown is very generous with their information when it comes to specification sheets, user manuals in addition to service manuals. I would recommend you download the service manual to get a good understanding on what this amplifier will present before shopping on ebay.
I am not into home audio so what necessities you require to suit your home audio needs in an amplifier other than raw power below 20 Hz I cannot offer. The most I can tell you is the Crown MA 2400 (Old Macro-Techs of that era pre-dating the I-Tech Series in general) will have no problem delivering it advertised wattage under 20 Hz long-term in an 8, 4, 2, or 1-ohm load for your home subwoofer.
There's also tecron which was a division of crown. There amps are rated to dc.
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Ah yes, thank you, that was one of the names I was trying to think of earlier when I mentioned the M600! I do want one at some point, would be cool to have that much power with no roll off 🙂 but they weigh as much as the moon and most are in the US, so shipping is a killer...
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