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Crown XLi vs XTi for DIY 18" Sub
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sebna View Drop Down
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Points: 20 		Post Options Post Options   Thanks (0) Thanks(0)   Quote sebna Quote  Post ReplyReply Direct Link To This Post Posted: 03 November 2023 at 1:12pm
Originally posted by Earplug Earplug wrote:

Do you play to elephants?  LOL

Only creatures that can really appreciate anything under 25/30Hz.    


Tactile :)
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sebna View Drop Down
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Points: 20 		Post Options Post Options   Thanks (0) Thanks(0)   Quote sebna Quote  Post ReplyReply Direct Link To This Post Posted: 04 November 2023 at 1:44am
Another question if you would know the answer guys:

If I would like to bridge XLI 3500 into 8ohms. Would that impedance curve be a problem?


According to specification of BMS for this driver it never dips below 8ohm however measured impedance according to linked database (on the same page there is also the impedance graph from BMS specification) it dips to 5.7ohm.

Would it be a problem for xli 3500, which does not support anything lower than 4ohm so 8ohm bridged?

In addition, driver is rated at 1500W RMS and 3000W peak power handling. How big of a risk would be running it by bridged XLI 3500 which is 2700W into 8ohm and peak probably over 5000W. 

From my very limited understanding, it is good to have over powered AMP vs capabilities of speakers as risk of clipping of amp is more dangerous and have potential to happen easier than over-driving 1500W peak 3000W driver in home setting, especially with 4 of them in the room?

Or, on the other hand - do I even have to worry about clipping amp rated @1000W per channel (with peak probably at 1200W) driving 1500W peak 3000W driver in home setting etc. as I would not be driving them that hard or loud due to being in a home setting and having 4 of them?

Which is a better option? I have enough amps to use them bridged or not.

Also would running them bridged give me more headroom for dynamics and well needed headroom in low end registers 30hz and below (where power of amps naturally drops and where power is most needed if someone wants to reproduce below 30hz)?

Thank you, trying to understand it better.

Thanks


Edited by sebna - 04 November 2023 at 1:56am
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Conanski View Drop Down
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Points: 2757 		Post Options Post Options   Thanks (1) Thanks(1)   Quote Conanski Quote  Post ReplyReply Direct Link To This Post Posted: 04 November 2023 at 3:59am
Originally posted by sebna sebna wrote:

From my very limited understanding, it is good to have over powered AMP vs capabilities of speakers as risk of clipping of amp is more dangerous and have potential to happen easier than over-driving 1500W peak 3000W driver in home setting, especially with 4 of them in the room?

Or, on the other hand - do I even have to worry about clipping amp rated @1000W per channel (with peak probably at 1200W) driving 1500W peak 3000W driver in home setting etc. as I would not be driving them that hard or loud due to being in a home setting and having 4 of them?

Which is a better option? I have enough amps to use them bridged or not.
Thanks

You have some separate DSP processig for this setup correct? Does it include limiting?

With subwoofers the biggest danger is always overpowering, you can damage them with too much peak excursion or theremally from too much steady state power, clipping an amp is another way to put more power into them(unintentionally) but it's not instant death like it is with mid/hi drivers. 

1000w per driver is nothing to sneeze at so you should try it that way first, if you get the amps into clipping and the drivers aren't complaining then try them bridged. But there is something you need to be aware of, in sealed boxes the drivers will need a fairly large EQ boost to be flat into single digits, that will quickly eat up amp headroom and driver excursion, so you really need to model your proposed design to see how it will perform at the lowest frequencies, I suspect the drivers will hit excursion limitations long before they get close to power limitations.
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sebna View Drop Down
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Points: 20 		Post Options Post Options   Thanks (0) Thanks(0)   Quote sebna Quote  Post ReplyReply Direct Link To This Post Posted: 04 November 2023 at 9:05am
Originally posted by Conanski Conanski wrote:

Originally posted by sebna sebna wrote:

From my very limited understanding, it is good to have over powered AMP vs capabilities of speakers as risk of clipping of amp is more dangerous and have potential to happen easier than over-driving 1500W peak 3000W driver in home setting, especially with 4 of them in the room?

Or, on the other hand - do I even have to worry about clipping amp rated @1000W per channel (with peak probably at 1200W) driving 1500W peak 3000W driver in home setting etc. as I would not be driving them that hard or loud due to being in a home setting and having 4 of them?

Which is a better option? I have enough amps to use them bridged or not.
Thanks

You have some separate DSP processing for this setup correct? Does it include limiting?

With subwoofers the biggest danger is always overpowering, you can damage them with too much peak excursion or thermally from too much steady state power, clipping an amp is another way to put more power into them(unintentionally) but it's not instant death like it is with mid/hi drivers. 

1000w per driver is nothing to sneeze at so you should try it that way first, if you get the amps into clipping and the drivers aren't complaining then try them bridged. But there is something you need to be aware of, in sealed boxes the drivers will need a fairly large EQ boost to be flat into single digits, that will quickly eat up amp headroom and driver excursion, so you really need to model your proposed design to see how it will perform at the lowest frequencies, I suspect the drivers will hit excursion limitations long before they get close to power limitations.


Thank you, that is great info.

For DSP purposes I will be using MiniDSP Flex Balanced version. I am not sure but I don't think it has limiting functionality (XLi amps don't). I will check that.

Originally posted by Conanski Conanski wrote:

But there is something you need to be aware of, in sealed boxes the drivers will need a fairly large EQ boost to be flat into single digits, that will quickly eat up amp headroom and driver excursion...

In terms of Amp headroom. Would bridging it into 8ohm for 3700W RMS be the answer to over come it or at least increase the original headroom "some" fold? I understand now that I might hit other limiting factors first but just purely on Amp level?

I came across such opinion:

Quote
The advantage of bridge is that it delivers the same power as a single ended amplifier with only half the rail Voltage. (40V RMS into 8R = 200 Watt) 40V RMS from a single ended amplifier requires + – 60V rails, whereas 40V RMS from bridged amps only requires + – 30V rails. With bridged amps the speaker is powered from both + – V rail supplies at the same time, instead of alternate between supply rails as with a single ended amp. Therefore Bridge amps make more efficient use of the rail supplies. Also the maximum Voltage across the transistors is half by comparison to single ended amp. Bridge is the most effective method to drive a speaker. The only disadvantage is higher cost.

Does it makes sense, is it true, does it matter with my implementation? How does it impact use with home 230v circuit if at all?

I will start on cab design soon - so I will be modelling all those parameters soon. What I should have said is that I will start researching how to model a sub cab as I have never done it before.

Would you have any reply to my question about measured impedance curve for 8ohm driver diving to 5.3 ohms and if it would be a problem for 8ohm rated XLi 3500 when bridged into 8ohm?
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Earplug View Drop Down
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The impedance seen by the amp will depend on the cabinet. The specs are for free air. Very different when put in a cab.

You need to check that when deciding on a design.


EDIT:- Also, try not to overthink this. Everything will be a compromise. Often you won't know until you build & test. That's how most good systems are made.   Smile

And does B&C have a recommended cab design for the driver?




Edited by Earplug - 04 November 2023 at 10:06am
Earplugs Are For Wimps!
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sebna View Drop Down
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Points: 20 		Post Options Post Options   Thanks (0) Thanks(0)   Quote sebna Quote  Post ReplyReply Direct Link To This Post Posted: 05 November 2023 at 3:29pm
Originally posted by Earplug Earplug wrote:

The impedance seen by the amp will depend on the cabinet. The specs are for free air. Very different when put in a cab.

You need to check that when deciding on a design.


EDIT:- Also, try not to overthink this. Everything will be a compromise. Often you won't know until you build & test. That's how most good systems are made.   Smile

And does B&C have a recommended cab design for the driver?

As far as I know they only recommend optimal volume rather than exact design.

Would box design / simulation tools show me predicted impedance?
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