For anyone with a memphis amp....or can answer question

[BlkonBlkFG 10+ year member]

I've got a memphis audio MCA300.4 amp for my interiors...I know what crossover setting I want them at, but how do I set it exactly there?? On memphis amps it shows 40hz on the low side and 600hz on the high side. No numbers at all inbetween. So how exactly do I figure out where I'm truly at?

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[PhatTonyDeMarco 5,000+ posts]

Mathematics, my boy //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

1/4 of the way up would be 175Hz; the middle of those would be 310Hz; and 3/4's would be 455Hz... Hope that helps ya find your sweet spot.

 

[squeak9798 5,000+ posts]

Mathematics, my boy //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif
1/4 of the way up would be 175Hz; the middle of those would be 310Hz; and 3/4's would be 455Hz... Hope that helps ya find your sweet spot.

That assumes that the pot is linear and not logrithmic.

 

[squeak9798 5,000+ posts]

I've got a memphis audio MCA300.4 amp for my interiors...I know what crossover setting I want them at, but how do I set it exactly there?? On memphis amps it shows 40hz on the low side and 600hz on the high side. No numbers at all inbetween. So how exactly do I figure out where I'm truly at?

The frequency itself isn't important.

All that matters is that you set it at the point that sounds the best. Is that at 51hz? Or 67hz? Or 82hz? I don't know...and it isn't really relevant.

Just set it to the point that sounds best and produces the best performance for the speakers in your setup, in your installation, in your vehicle.

Also...without truly listening to it to determine the optimal crossover point, how do you know where you want it set?

So, just set it to a point that sounds the best to you in your setup. Don't worry about what specific frequency that may be.

 

[thch 10+ year member]

you can also use a DMM. turn filter off. play test tone at frequency of interest. turn HU up to a volume setting that gives 14.14V. turn on filter. with same settings, adjust filter to get voltage of 10.00V. this will be the -3dB point, which is the defined cutoff for most audio filters. this will give a scientific crossover point. from here, you may want to adjust filters to what works best.

 

[BlkonBlkFG 10+ year member]

will this be done after i set my gains to their configured voltage? So i set the crossover it a flat setting? and not in the HPF setting?

 

[squeak9798 5,000+ posts]

You will want to set the crossover before you play the speakers at any kind of real volume level. So if you are setting the gain by ear, set the crossover first. If you are setting the gain with a DMM (i.e. with the speakers not connected), then you can do it after you set the gain but before you play the speakers at normal listening levels. For setting the gain...the DMM method is sort of a rough guess anyways...it may need to be adjusted some by ear after you get the xover set and the speakers playing.

Anyways, thch's method was to give you an idea of where a specific frequency is. For example; if you wanted to set the xover to 80hz...you would set the filter to flat or off and play an 80hz tone at a level of 14.14V on the DMM (if you already have the gain set, you would raise/lower the voltage reading on the DMM via the headunit's volume control). You would then engage the highpass filter (i.e. turn it on), play the same 80hz tone at the same volume setting and turn the frequency pot until the reading on the DMM dropped to 10.00V.

However, like I said above....don't concern yourself with a specific frequency. It sounds like you haven't even played the speakers yet, so you honestly have no idea what frequency will provide best performance for your setup anyways. And beyond that....knowing the specific frequency is academic anyways. The specific frequency isn't important as long as the setting you selected provides the best performance for your particular setup.

So don't confine yourself to trying to get the xover set to one particular frequency.

 

[BlkonBlkFG 10+ year member]

Yes, I have listened to the speakers and do have them installed allready. I just want to make sure I can have them loud and safe at the same time. I'm kind of new to the specifics of settings, so im kind of learning as i go along. According to memphis audio's website on their speaker info ratings it says... "These safe power ratings assume use of proper high pass crossover on mid-range. Sugguested crossover frequency for 6.5" is 80Hz @ 12dB."

Thats why I was trying to set them at 80Hz ?

What do you think?

 

[thch 10+ year member]

oh, and the DMM thing works in reverse (usually*) as well. set crossover, turn off crossover, set output voltage to 14.14V. turn on crossover. change frequency until output reads 10.00V.

This can give you valuable information, eg, "my crossover sounds good and is set at 72hz".

in this manner you can set the crossover to what sounds good, then find the crossover point to ensure it is 80hz or higher. if it is not, then you can either raise it to 80hz, or decide to play it at a lower volume (or maybe not, your call).

* there are filters not normally used for audio for which this will not be true. such filters have multiple freqeuncies that are -3dB.

 

[squeak9798 5,000+ posts]

Yes, I have listened to the speakers and do have them installed allready. I just want to make sure I can have them loud and safe at the same time. I'm kind of new to the specifics of settings, so im kind of learning as i go along. According to memphis audio's website on their speaker info ratings it says... "These safe power ratings assume use of proper high pass crossover on mid-range. Sugguested crossover frequency for 6.5" is 80Hz @ 12dB."
Thats why I was trying to set them at 80Hz ?

What do you think?

Set it by ear based what sounds best.

Don't restrict yourself to a single frequency.

If you really must absolutely know what frequency it's set to, then do as thch suggested and "reverse engineer" it and figure out where it's set after you have set it based on what provides you the best sonic performance.

 

[BlkonBlkFG 10+ year member]

So you guys reccomend setting my gains with the digital volt meter? So set the crossover where I think it sounds good, and then set the gain once I have that figured out?

 

[squeak9798 5,000+ posts]

The DMM method for gain setting is a good way to give you an approximation of the highest you should set the gain (within the confines of the accuracy of that particular method).

You could set it by the DMM, and then do some tweaking by ear after you listen to them. You may, for example, need to turn the gain down some after you listen to it with the DMM setting.

 

[BlkonBlkFG 10+ year member]

ok cool...I mean I understand that it will all ultimately depend on my ears, but I atleast want to know where my max setting should be. Its a memphis mca300.4 so I know right off the bat its underpowered b/c the 75x4 rating is at 12v. Memphis told me it does 90x4 @ 14.4v. But for my voltage setting for the max gain i'm going to use the formula of 75x4. I'll set my crossover based on how I think it sounds but atleast use the DMM method for a max gain setting and then adjust down from there.

 

[BassAddictJ 5,000+ posts]

tune it by ear. find where they sound the best, best being as loud as they can get WITHOUT getting disorted, then set it back jsut a hair...

bump for one of my favorite amps //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[PhatTonyDeMarco 5,000+ posts]

tune it by ear. find where they sound the best, best being as loud as they can get WITHOUT getting disorted, then set it back jsut a hair...
bump for one of my favorite amps //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

It's nearly impossible to detect proper distortion in subsonic frequencies... Get a DMM and do it properly, or more so an o-scope.