Hi all!
I am in the process of finalizing my design of a MTM DIY speaker. I have the cabinet modeled, crossover pretty close to final, but what I am now concerned with is amplification. I know this can be a controversial subject, but I hope I can at least get a better understanding of things.
My crossover should have a final impedance of 4ohms. From my understanding, the woofers usually are the ones who determine the power handling and impedance of the speaker. I am using 2x DA RS150 8ohm woofers in parallel, and a DA RS28 4 ohm Tweeter. The combined RMS handling of the woofers should be 80watts (40 watts each), and the tweeter is 80 watts at 4ohms on its own. I am looking to use the Anthem MRX740 AVR and then the Emotiva BasX A3 3 channel amp for the three MTM speakers I am trying to build. I am looking to make these speakers into a LCR set up for music and home theatre. The BasX amp can push 200watts RMS into 4ohm with all channels driven (or 140watts into 8ohms).
I am afraid this might be over kill for these speakers though... I have heard that it can be beneficial to run speakers 1.5x above their RMS for dynamics as long as you are not listening to it too loud as to use all its power for too long which may fry the voice coil or cause mechanical damage. I generally don't like to listen to anything much above 90-105db for very long, and music usually is comfortable for me at around 90-95db. Would this be a good, or bad pairing?
Any thoughts or suggestions? TIA
I am in the process of finalizing my design of a MTM DIY speaker. I have the cabinet modeled, crossover pretty close to final, but what I am now concerned with is amplification. I know this can be a controversial subject, but I hope I can at least get a better understanding of things.
My crossover should have a final impedance of 4ohms. From my understanding, the woofers usually are the ones who determine the power handling and impedance of the speaker. I am using 2x DA RS150 8ohm woofers in parallel, and a DA RS28 4 ohm Tweeter. The combined RMS handling of the woofers should be 80watts (40 watts each), and the tweeter is 80 watts at 4ohms on its own. I am looking to use the Anthem MRX740 AVR and then the Emotiva BasX A3 3 channel amp for the three MTM speakers I am trying to build. I am looking to make these speakers into a LCR set up for music and home theatre. The BasX amp can push 200watts RMS into 4ohm with all channels driven (or 140watts into 8ohms).
I am afraid this might be over kill for these speakers though... I have heard that it can be beneficial to run speakers 1.5x above their RMS for dynamics as long as you are not listening to it too loud as to use all its power for too long which may fry the voice coil or cause mechanical damage. I generally don't like to listen to anything much above 90-105db for very long, and music usually is comfortable for me at around 90-95db. Would this be a good, or bad pairing?
Any thoughts or suggestions? TIA
What I like to do before I build an amp is to cross and balance the driver or speaker close to the way I intend to use it, then connect the amp output to my oscilloscope. I use them for a time at the expected levels and I can easily see the Voltage rail requirements. In cases where current is uncertain it is easy enough to measure that too using a sense resistor.
Running a speaker system at double its RMS rating with typical music program for extended periods isnt likely going to hurt anything. You will probably see a tiny bit of power compression and TSPs will drift a bit, but it wont be that noticeable IMO. The VCs found in most modern drivers (even cheap ones) use very capable materials and adhesives, which are immune to the kind of temps they'll be seeing.
I know it's a whole can of worms basing things off of modeled measurements vs real measurements, but my issue is that I do not currently have an amp and would like to order the Emotiva, but what I am concerned about is wasting my money on it only to find out it is way too over powered for my speakers.
In a ballpark guess, is it relatively safe to assume that the speakers RMS is equivalent to the woofers combined RMS of 80 watts assuming the impededence curves look reasonable? (They are 8ohm speakers in parallel to make them 4 ohms.) And secondly, assuming I'm not cranking it to 120db for long periods, is the 200rns at 4ohms of the amp "safe" for these hypothetical speakers?
Thank you for your input! So you don't think this amp is way overkill for these diy speakers? I am just having trouble finding an external 3 channel amp that does less than 200rms at 4ohms. From your understanding, is it safe to assume the RMS for these speakers is 80 watts? (dual 8ohm into 4 ohms parallel load that have 40watt RMS each and a 4ohm 80watt tweeter).
Assuming your bass drivers are nominal 8 Ohm and 88dB at 2.83V, then two of them in parallel, with a baffle step compensation of 4dB, need 1W for 87dB. With 64W into 4 Ohm you reach 105dB. The point is, at 64W have you reached xmax or not? This answer depends on the tuning you have chosen, I use Unibox to find out the SPL a driver can sustain without distortion in the intended box. With a single driver I usually find that the driver runs out of excursion before the specified power handling.
Having said that, between an underpowered amp and an overpowered one, the latter is to be preferred, because the former can run easily into distortion when trying to drive the speaker to a high SPL.
Ralf
Having said that, between an underpowered amp and an overpowered one, the latter is to be preferred, because the former can run easily into distortion when trying to drive the speaker to a high SPL.
Ralf
Hmmm... That is a great point. I just ran the drivers in parallel through winISD with my previously designed vented box tuned at 67hz. The xmax is hit at 93hz at only 90watts (16.8V) giving around 102db of max spl at 77hz. I guess that answers my question pretty quick. I understand its based off of how much power I give the drivers, but 200rms per channel sounds like I would be playing with fire pretty easily haha. I guess I will have to find a different amp, or perhaps consider a series crossover or different drivers.
Thank you, Ralf!
Also, even if the amp in theory is overkill, just don't turn the volume control up to '12'.
The nice thing about overkill amps is that you can play the speaker at the level it can handle, without the amp running out of steam.
You'll easily hear when the speaker starts to distort.
There really isn't a compelling reason to limit amp power, unless you have teenagers in the house that would turn it up all te way in an effort to lift off the roof.
Jan
The nice thing about overkill amps is that you can play the speaker at the level it can handle, without the amp running out of steam.
You'll easily hear when the speaker starts to distort.
There really isn't a compelling reason to limit amp power, unless you have teenagers in the house that would turn it up all te way in an effort to lift off the roof.
Jan
