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Is there way to check the actual frequency output of an Amp or DSP?

 

The situation I am having is I run a stock HU to a DSP to amps to speakers.

 

I have blown a new set of high-mids that are supposed to be high-passed at 500HZ. Since they blew, rather fast too , the consensus is that I am running too low of a signal to them. Therefore since my DSP is set at 500 and up, how can I test that and see if this is really what’s happening or if the DSP is wrong? 
 

I don’t want to run this again and have the same thing happen. 
 

Should I also have the amp HighPassed at 500hz even though the signal to the amp is already “supposedly” set at 500hz? 
 

In this situation not only is the signal high passed at the DSP but I also have inline filters before the mids. Seems like one or both should have prevented a blown speaker or in my case 2 blown speakers. 
 

Something ain’t right and I can’t put my finger on it. 

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If you measure with a multimeter at the speaker outputs from the amp in question, and play a sweep, once you fall below 500 hz, the voltage will start to decrease. That's one way to check. 

2011 Chevy Silverado under construction

My build log here. Check it out! 

 

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3 hours ago, Fuzz said:

Is there way to check the actual frequency output of an Amp or DSP?

 

The situation I am having is I run a stock HU to a DSP to amps to speakers.

 

I have blown a new set of high-mids that are supposed to be high-passed at 500HZ. Since they blew, rather fast too , the consensus is that I am running too low of a signal to them. Therefore since my DSP is set at 500 and up, how can I test that and see if this is really what’s happening or if the DSP is wrong? 
 

I don’t want to run this again and have the same thing happen. 
 

Should I also have the amp HighPassed at 500hz even though the signal to the amp is already “supposedly” set at 500hz? 
 

In this situation not only is the signal high passed at the DSP but I also have inline filters before the mids. Seems like one or both should have prevented a blown speaker or in my case 2 blown speakers. 
 

Something ain’t right and I can’t put my finger on it. 

 

If the inline filters belong to the mids lower frequecies won't pass no matter what. Most likely you just overpowered.

 

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That’s what I am thinking. I basically have two failsafes and still, poof!

 

I am nervous now to try again. The manufacture warrantied the speakers but suggested a crossover rather than the inline filters, that they made for these speakers… Pretty much said there must be something wrong with the DSP, but they don’t know I have been running this same system with another brand of speakers without any problems. 
 

I feel like my signal is safe because the 2” mid drivers blew but not the Tweeters that are on the same channels. Both behind their inline filters. 
 

probably these can’t handle the power, but really it’s not all that much. 100 watts to the 2” and 1” drivers. 

 

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2 hours ago, Fuzz said:

That’s what I am thinking. I basically have two failsafes and still, poof!

 

I am nervous now to try again. The manufacture warrantied the speakers but suggested a crossover rather than the inline filters, that they made for these speakers… Pretty much said there must be something wrong with the DSP, but they don’t know I have been running this same system with another brand of speakers without any problems. 
 

I feel like my signal is safe because the 2” mid drivers blew but not the Tweeters that are on the same channels. Both behind their inline filters. 
 

probably these can’t handle the power, but really it’s not all that much. 100 watts to the 2” and 1” drivers. 

 

Crossover point is defined as -3db

Which corresponds to a voltage change of 1/√2

So what you do is turn the crossovers off / down / up / etc. Make them not filter anything

Play a 500hz sine wave at some arbitrary volume with the speakers disconnected, and measure acV (10v for example)on your amp's output. Write that number down, divide it by √2, then there's your -3db point (7.1v for example)

Now play 500hz again, at the same volume, after setting your crossover. If the voltage is higher than the number you just calculated, the HP is set <500hz. If the voltage is lower than calculated, then the HP is >500hz. If everything matches up, then you're set where intended.


Note that not all multimeters to higher frequency stuff, so YMMV. 500hz is *usually* in spec, but you're pushing the limits there. I usually use this method to set low pass filters on subs / mid-bass drivers. in the 50-120hz range

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3 hours ago, pnutz37 said:

What year and type of vehicle? What DSP? I'm assuming you're running high level to the DSP?

I am having issues with this type of set up and I'm just trying to figure out if you're having the same.

17 tundra 

Alpine PXE 0850 

never had this problem till installing new speakers.  I do not think it’s my signal, since other speakers held up just fine for well over a year. 

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3 hours ago, Fuzz said:

17 tundra 

Alpine PXE 0850 

never had this problem till installing new speakers.  I do not think it’s my signal, since other speakers held up just fine for well over a year. 

The issue that I have (And you may have similar - i'm in a 2017 VW Golf). Some of the newer stock head units need to see a certain resistance at the speakers when sending the signal. When using high level to DSP this changes. My DSP does not offer enough resistance for the head unit therefore it sends more signal to achieve the volume I'm set at. Then I get all sorts of distortion for my front stage.

 

This occurs in newer BMW cars and the shop I go to has a few work arounds to combat this issue. Most of them involve getting the correct DSP or a DSP amplifier. I do know some of the Audiocontrol DSP's (LCi 2 Pro and LCi 7) work for this as well.

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  • 3 weeks later...
On 5/2/2022 at 6:20 AM, Fuzz said:

Pretty certain I’ll be working with a new HU soon enough. 

To follow up on this. I got my new DSP installed and there still is distortion coming through from the stock headunit after about 15 on the volume (The volume goes to 30). This is with the eq flat as well. Anything louder than 15 would go to distortion. 

Because it's a VW there's a chance I can use VCDS (Their coding interface) to gain access to the head unit and actually flatten the eq vs what the display says.

 

It's been an expensive and frustrating rabbit hole. In the end it works, no distortion on any channel and feel comfortable sending it.

 

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