Crown amplifiers for subs

[martyh]

Hello, has anyone tried one of these crown CDi amps for subwoofer use? The cinema chain we build for has been installing a version of these for a few years now. The onboard dsp and crossover functions are intriguing. I’ve watched them EQ their systems and the user interface via a laptop looks easy to work with. The 275 watt stereo version can be had for under 600 U.S.
Thanks, Marty

http://www.crownaudio.com/amp_htm/cdi.htm

[Owen Bartley]

Marty, I know a lot of people use Crown amps for subs, I'm just not sure about that specific model. Another favourite are the Behringer Europower line which can be had for pretty good prices too, and are a good bang for the buck amp.

[a1161979]

Although crown are great amplifiers i would lean towards QSC

QSC amplifiers seems to have a stronger following than Crown, also although i cant remember where i saw it but QSC amplifiers seem to be better at delivering power into low Frequencies than similar Crown models. The cinema company i workerd for once used local maufactured amplifiers for the mains/surrounds (Australian monitor) yet we allways used QSC amplifiers for the LFE and never had problems...

In fact the subs had the problems... ahhh memories of the first screening of U571... Out of four driver two rattled afterwards and one was completly gone

[jeffreybehr]

Hmm...1400 Watts in 4 Ohms, mono, from the 'little' one. Wow. FOURTEEN parametric eqs and 6 different slopes for low-pass certainly ought to get a power-hungry SW system running well.

Three-year transferable warranty, too.

[ccdoggy]

remember that when looking at those wattage numbers that it is not consistent throughout the frequency spectrum. typically sloping down the lower you go. Thus some amps will output less power at sub levels then others even though they may both be rated at 1400 watts.

[eyekode]

martyh wrote:

Hello, has anyone tried one of these crown CDi amps for subwoofer use? The cinema chain we build for has been installing a version of these for a few years now. The onboard dsp and crossover functions are intriguing. I’ve watched them EQ their systems and the user interface via a laptop looks easy to work with. The 275 watt stereo version can be had for under 600 U.S.
Thanks, Marty

http://www.crownaudio.com/amp_htm/cdi.htm

I also think the Crown XTI series will work well. I believe it has a very similar on-board DSP. And you can buy "B" stock for 400$ shipped off ebay. But what I am really interested in is a "low" power class-D amp. I don't need more then 500W, but I really need it to be efficient. Looks like a BASH plate amp is my best bet.

[a1161979]

ccdoggy wrote:

remember that when looking at those wattage numbers that it is not consistent throughout the frequency spectrum. typically sloping down the lower you go. Thus some amps will output less power at sub levels then others even though they may both be rated at 1400 watts.

Yes this is correct, not to mention rating are often false, for example the EP2500 could only produce 1900 watts at 20Hz into a four ohm load instead of the rated 2400

I have been looking and i wish i could find it but i read somewhere (i think it was Prosoundweb) that Crown aplifiers when compaired with other didnt perform aswell in the lower frequencys. This was however their lower line up, i am not going to fight with the larger I tech series which to be simply honest are mean mean amplifers

[jeffreybehr]

All of these less-power-at-lowest-frequencies stories may be true, but if one uses it ONLY for low frequencies, it may well be able to deliver close to its 1KHz-rated power. Besides that, most of us VERY RARELY use that much power from an amp, so if I choose to use a 1000 in stereo driving FOUR 8-Ohm drivers in parallel for a 2-Ohm load per channel and it's able to deliver 'only' 500-600 instead of 700 Watts per channel, it'll do just finely, TYVM.

We'll see. BTW my now-just-a-fantasy project is an infinite-baffle super-subwoofer system built into a wall that backs into my highly accessible attic. I'll be using at least 6 (and maybe 8) Sonic Craft SC300 12" drivers that are highly suitable for such IB use. Here's a pic of that wall with some very rough indications of where the drivers probably will go. The goal is excellent energy in the 15 - 30Hz range, and I believe such a system will do the job.

http://i89.photobucket.com/albums/k2...0w_w8holes.jpg

[a1161979]

jeffreybehr wrote:

All of these less-power-at-lowest-frequencies stories may be true, but if one uses it ONLY for low frequencies

Id like to take the time to point out this is in the DIY Subwoofer section and the title is Crown Amplifers for subs... i would presume that being a subwoofer the OP would in fact only be using it for low frequencies

Now if he really needs that much power is a different argument and off topic

[martyh]

Hi,
Thanks for all of the replies. The thing that intrigued me most about these amps was the built-in dsp. For a couple of hundred more than the cost of a behringer dcx I could have the dsp and two channels of amplification. Since posting I’ve learned that the dsp is as flexible as I thought it might be but the amplifier topology is suspect. I thought it was “class I” but it class ab/b with a switching supply. In the end it seems that using a dcx with my existing QSC 1400 amps may be the best option. I’m really not keen on trying out a switching supply with class B operation.

[eyekode]

martyh wrote:

Hi,
Thanks for all of the replies. The thing that intrigued me most about these amps was the built-in dsp. For a couple of hundred more than the cost of a behringer dcx I could have the dsp and two channels of amplification. Since posting I’ve learned that the dsp is as flexible as I thought it might be but the amplifier topology is suspect. I thought it was “class I” but it class ab/b with a switching supply. In the end it seems that using a dcx with my existing QSC 1400 amps may be the best option. I’m really not keen on trying out a switching supply with class B operation.

What do you see as the issue? Don't think a switching supply has the power reserves of linear supply?

[martyh]

eyekode wrote:

What do you see as the issue? Don't think a switching supply has the power reserves of linear supply?

I don’t know that there is anything wrong with a switching supply per se, or, class B for that matter. I think that both of those options are sometimes used more because they are inexpensive than because they sound better for a given application. Considering that I haven’t heard from anyone who has actually used one of these amps in a home setting, I’ll probably just stick with the older amps and get the dsp via a dcx.

[Bob_99]

martyh wrote:

Hi,
Thanks for all of the replies. The thing that intrigued me most about these amps was the built-in dsp. For a couple of hundred more than the cost of a behringer dcx I could have the dsp and two channels of amplification. Since posting I’ve learned that the dsp is as flexible as I thought it might be but the amplifier topology is suspect. I thought it was “class I” but it class ab/b with a switching supply. In the end it seems that using a dcx with my existing QSC 1400 amps may be the best option. I’m really not keen on trying out a switching supply with class B operation.

I was also looking at the Crown supplies because of their dsp but this post makes me ask, does it make a difference what class amp or whether it is a switching supply when dealing with low frequencies? It's been a while since I've studied amplifiers and have forgotten what little I use to know. Interesting though to see things like class 'H' and 'I'.

Bob

[jeffreybehr]

After reading the specs, I e-mailed crown with some questions. Here's Crown's response.

"Mr. Behr,

<< what's the calculated -3dB point on the hi-pass pole(s)? >>
The amplifier's DC protection will disable the power supply at 7Hz.

<< Do you have a Power-Bandwidth spec for it? >>
We guarantee the frequency response from 20Hz to 20KHz. Because of slew rate limiting the response begins to roll off at (roughly) 29KHz at 6 dB per octave.

<< will the amp operate correctly driven by an unbalanced signal >>
Yes. This is common practice. There is a limit of 15 feet (5 meters).

If you have any further questions, please write.

David Engstrom
Crown Technical Service Department
(800)342-6939
(574)294-8224"

I ordered a CDi 2000; we'll see. With a power rating of a kiloWatt per channel into 2 Ohms, it sure ought to drive that IB supersub.

[a1161979]

jeffreybehr wrote:

After reading the specs, I e-mailed crown with some questions. Here's Crown's response.

"Mr. Behr,

<< what's the calculated -3dB point on the hi-pass pole(s)? >>
The amplifier's DC protection will disable the power supply at 7Hz.

<< Do you have a Power-Bandwidth spec for it? >>
We guarantee the frequency response from 20Hz to 20KHz. Because of slew rate limiting the response begins to roll off at (roughly) 29KHz at 6 dB per octave.

<< will the amp operate correctly driven by an unbalanced signal >>
Yes. This is common practice. There is a limit of 15 feet (5 meters).

If you have any further questions, please write.

David Engstrom
Crown Technical Service Department
(800)342-6939
(574)294-8224"

I ordered a CDi 2000; we'll see. With a power rating of a kiloWatt per channel into 2 Ohms, it sure ought to drive that IB supersub.

Have i read that wrong or do these amplifiers have a wall at 7Hz? Bossobass over at AVS with his argument that sealed boxes with proamps are the best for infrasonics has just failed Very interesting... So the people building sealed subs for 10hz and down are gaining nothing

Presumably if crown does this then many others probably do aswell Very interesting

[Ricci]

Most amps have some sort of filter below 10hz. Usually 5-8hz.

[ISLAND1000]

I use the Crown XTi 4000. It has awesome response at 10Hz, I can see it and feel it. The DSP is sensational. Pick a curve, any curve, it'll do it.