Hello friends,
I am currently building a pair of DIY passive subwoofers for my home (mostly for TV and movies) with 200 watts RMS for each sub.
Since I am building a passive sub, I had bought miniDSP 2x4 HD version along with REW UMIK-1 mic for measurement. I will use them to measure the raw response of the subwoofers (after dialing in the gain) and correct/enhance the responses using house curve. Now, coming to selection of amp part is where I am stuck, class D or class AB. Given the RMS ratings for my subwoofers, I potentially look at these 2 right now - Crown xls 1002 (class D) or Crown xli 800 (class AB). With the below understanding of the pros and cons, could you please enable me to make an informed decision on my purchase? I really count the expert opinions here.
Option 1
Crown xls 1002 (350 watts, RMS?)
Pros:
1. Class D design, runs cool and draws little power, just about 18 watts at idle and 25 watts right below clipping
2. Sound quality (from what I've heard reviews about xls series is really good for subs)
3. Has additional DSP features (which I wont use as I have advanced DSP equipment, miniDSP)
Cons:
1. Due to its inbuild DSP capabilities, I believe it limits the output signal down to 48khz even though the input signal has a higher bandwidth (from miniDSP)?
Question - Do I really need to worry about the negative on limiting the output signal to 48khz?
Option 2
Crown xli 800 (300 watts, RMS?)
Pros:
1. Class AB sound quality is warm and better than class D
2. Since there is no inbuilt DSP on this amp, what is fed in comes out clean as output
Cons:
1. Highly inefficient as it draws 38 watts in idle and between 240 and above during normal operation and dissipates enormous amount of heat.
Option 3
Would I do better if I make an DIY class AB amp which puts out below 100 watts RMS? The idea behind this thinking is that with the miniDSP I have the capability to boost the input signal using EQ (on house curve by applying low shelf) and the amp would only need little power to make the subs play at desired levels of SPL (say 75 db)
With the above summary and given the fact that xli 800 which can consume lots of power, I feel crown xls 1002 would be better equipment for me. However, I am not certain on the signal bandwidth limitations I have highlighted in cons.
Please advise.
Thanks
I am currently building a pair of DIY passive subwoofers for my home (mostly for TV and movies) with 200 watts RMS for each sub.
Since I am building a passive sub, I had bought miniDSP 2x4 HD version along with REW UMIK-1 mic for measurement. I will use them to measure the raw response of the subwoofers (after dialing in the gain) and correct/enhance the responses using house curve. Now, coming to selection of amp part is where I am stuck, class D or class AB. Given the RMS ratings for my subwoofers, I potentially look at these 2 right now - Crown xls 1002 (class D) or Crown xli 800 (class AB). With the below understanding of the pros and cons, could you please enable me to make an informed decision on my purchase? I really count the expert opinions here.
Option 1
Crown xls 1002 (350 watts, RMS?)
Pros:
1. Class D design, runs cool and draws little power, just about 18 watts at idle and 25 watts right below clipping
2. Sound quality (from what I've heard reviews about xls series is really good for subs)
3. Has additional DSP features (which I wont use as I have advanced DSP equipment, miniDSP)
Cons:
1. Due to its inbuild DSP capabilities, I believe it limits the output signal down to 48khz even though the input signal has a higher bandwidth (from miniDSP)?
Question - Do I really need to worry about the negative on limiting the output signal to 48khz?
Option 2
Crown xli 800 (300 watts, RMS?)
Pros:
1. Class AB sound quality is warm and better than class D
2. Since there is no inbuilt DSP on this amp, what is fed in comes out clean as output
Cons:
1. Highly inefficient as it draws 38 watts in idle and between 240 and above during normal operation and dissipates enormous amount of heat.
Option 3
Would I do better if I make an DIY class AB amp which puts out below 100 watts RMS? The idea behind this thinking is that with the miniDSP I have the capability to boost the input signal using EQ (on house curve by applying low shelf) and the amp would only need little power to make the subs play at desired levels of SPL (say 75 db)
With the above summary and given the fact that xli 800 which can consume lots of power, I feel crown xls 1002 would be better equipment for me. However, I am not certain on the signal bandwidth limitations I have highlighted in cons.
Please advise.
Thanks
48kHz is fine, especially for a sub. For option 3, higher input level does not mean power requirements change. At the end of the chain, the amp needs to deliver enough power to drive the speaker to desired output levels. Higher output from miniDSP just means lower gain is required from the amp. (Sorry if I misunderstood what you were saying there.)
The only real concern I'd have with the DSP amp is to make sure the receiver you're running from has enough delay to accommodate whatever delay the DSP amp adds by default on top of the miniDSP (assuming you're running the miniDSP off an AVR sub preout).
The only real concern I'd have with the DSP amp is to make sure the receiver you're running from has enough delay to accommodate whatever delay the DSP amp adds by default on top of the miniDSP (assuming you're running the miniDSP off an AVR sub preout).
Speaking only of class-D amps, are there amps that take digital input? (I suspect the mini-dip company has them.)
The whole matter of amp power has been discussed here a lot, usually to calm down screwball excesses. In short, you ought to estimate or measure power need for playing real loud in your room before buying an amp. Not easy to do because you need to decide how much distortion you accept for brief occasional peaks. Hint: you need an LED vu-meter that reveals short peaks in amp output. You can test power used at say 85bBC and estimate up from there.
You might just build the speakers and use any old amp you have sitting around (or second-hand old amp). Try 100 watts and see if that isn't all you ever need.
B.
The whole matter of amp power has been discussed here a lot, usually to calm down screwball excesses. In short, you ought to estimate or measure power need for playing real loud in your room before buying an amp. Not easy to do because you need to decide how much distortion you accept for brief occasional peaks. Hint: you need an LED vu-meter that reveals short peaks in amp output. You can test power used at say 85bBC and estimate up from there.
You might just build the speakers and use any old amp you have sitting around (or second-hand old amp). Try 100 watts and see if that isn't all you ever need.
B.
I am sorry but i don't quite understand this. Isn't the miniDSP where I get to set the delay which gets relayed to the amp as default configuration? I will get to determine this parameter after several iterations of measurements and I would for sure, disable the dsp capabilities in crown XLS 1002 so the sub gets the delay params from miniDSP. Why do I need to check/set the delay settings in AVR (marantz sr 5013). Please explain if you could.
Yeah i had this in my mind but as you pointed out it's cumbersome to simulate things to find out how much power do I need at what listening levels. Either i need to borrow or buy second hand stuff to make this happen which isn't easy option for me unfortunately. Thanks
OK, to start, are you powering other speakers from the AVR internal amps? If so, your AVR is still going to be responsible for setting delay between the main speakers and between mains and subs, which means the total delay required on the main speakers to match the total delay applied to the subwoofers needs to be within range for the AVR. (On the AVR you will see it shown the opposite way, so the speaker with lower distance will have a higher delay applied to it).
Even if you are not using the DSP on the XLS, the input is digitized prior to being turned back to analog for output, and may be processed somehow such as for gain. There will be some additional delay in this process. The AVR has a max limit for delay it can apply. It will probably be ok but just something to keep in mind as a potential downside to using an Amp with DSP after a miniDSP.
Thanks for the explanation. Assuming the delay which the crown XLS adds into the output is a fixed value, the only way to figure out how much delay we need to factor in to compensate for the delay in the output is to measure the signal with another amplifier (without dsp) that puts out same watts as the XLS amp and see how much delay the miniDSP would additionally need to match the response curve of the crown? I think it is just not a straight forward thing for sure but i do not know if it will degrade the sound quality of I go ahead with this set up.
In general, the way the measure the power output capacity from a class D and class AB amplifier are different, the class AB tend to use sinewave as input signal for 5min while class D tend to use burst signal. If you are able to match the peak power from both class, so both will be equivalent for piratical purpose.
checking the owner manual I see:
Crown xli 800 (class AB)
1 kHz (EIA) with 0.5% THD = 300W per channel @ 4ohm, this means that once the input is a sine wave with crest factor of 3, it means that your peak power is the double = 600W per channel.
Crown xls 1002 (class D)
There is no clear in indication about how the power was measure, so always assume as peak power.
350W per channel @ 4ohm
So, the XLI 800is the best option for peak output power.
XLS 1002 is the best option if you think about power consumption, class D has much higher efficiency.
checking the owner manual I see:
Crown xli 800 (class AB)
1 kHz (EIA) with 0.5% THD = 300W per channel @ 4ohm, this means that once the input is a sine wave with crest factor of 3, it means that your peak power is the double = 600W per channel.
Crown xls 1002 (class D)
There is no clear in indication about how the power was measure, so always assume as peak power.
350W per channel @ 4ohm
So, the XLI 800is the best option for peak output power.
XLS 1002 is the best option if you think about power consumption, class D has much higher efficiency.
No, you shouldn't need to use any other equipment. You will already be using REW to time align the subs for best response with the miniDSP controls. Once you do that, you will want to adjust the sub delay (distance) in the AVR to get optimal matching between the sub and main L&R(possibly C) in the crossover region. It's also advisable to align the main speaker channels distance manually with REW as D&M AVRs have apparently been using a distance to delay formula that is incorrect for years (see this thread -- there is also a thread on AVS about MultEQ-X which contains some information iirc).
Who
Thanks, should i consider XLS 1502 then (525 watts)? My subwoofer is rated at 200watts RMS, specs attached mentions for short term and long term power
Thanks, should i consider XLS 1502 then (525 watts)? My subwoofer is rated at 200watts RMS, specs attached mentions for short term and long term power
Thanks for the useful info. I think the ideal way is to adjust the determined numbers to see room for improvements.
Since there are no clouding issues related to delay, sound quality, or anything else, the only question, which seems to have scant attention here is power required. There's a long history at this forum of unsubstantiated views of how much power is needed and this thread contributes to that history by overlooking the topic, post #3 excepted.
So I'd say (again), figure out how much power you need by experimenting in your room.
B.
So I'd say (again), figure out how much power you need by experimenting in your room.
B.
Thanks @bentoronto, its when I almost zero in on my purchase of crown xls 1002, this confusion had come up. I have read good things about this amp for subwoofer channel but little did I know about it being bridged or independently used for dual subwoofers. With 350 watts claimed for 1002 model, would it be a better fit for driver with 200 watts RMS? and thats the answer I am looking for.
Sorry, I've lost track of the details and somebody else can be more helpful in light of the size of your room, etc. But I would point out that you couldn't hear differences in quality for driving a subwoofer among any competently designed amp made in the last 40 years, and I'd say 50 another day.
Experimenting with a borrowed amp and software oscilloscope is the way to go. But hard to imagine needing more than 200 watts, but just my guess.
B.
Experimenting with a borrowed amp and software oscilloscope is the way to go. But hard to imagine needing more than 200 watts, but just my guess.
B.