# Should all mid range speakers have bass blockers installed?



## corbmonster (Jan 25, 2015)

I have a pair of polk db651 from a previous car, still in great condition. I'm about to put them in my front door until other stuff comes in. Should I use bass blockers? What if they were amplified? What about components? Does the crossover for components block the bass range for the speakers that should be blocked, or does it just separate the highs to tweeters, and send everything else to the woofer?


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## DLO13 (Oct 24, 2010)

corbmonster said:


> I have a pair of polk db651 from a previous car, still in great condition. I'm about to put them in my front door until other stuff comes in. Should I use bass blockers? What if they were amplified? What about components? Does the crossover for components block the bass range for the speakers that should be blocked, or does it just separate the highs to tweeters, and send everything else to the woofer?


Audio crossover - Wikipedia, the free encyclopedia


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## cajunner (Apr 13, 2007)

corbmonster said:


> I have a pair of polk db651 from a previous car, still in great condition. I'm about to put them in my front door until other stuff comes in. Should I use bass blockers? What if they were amplified? What about components? Does the crossover for components block the bass range for the speakers that should be blocked, or does it just separate the highs to tweeters, and send everything else to the woofer?


very few aftermarket component sets come with any bandpass circuit on the midranges.

since most people are using component speakers without subwoofers, (in general, and how companies market their speaker sets) the ability of the woofer to dig down a bit is a necessary attribute, and putting in a passive cut-off for the woofers is almost universally not implemented.

but it doesn't mean you can't do it, but it isn't like tweeter protection in that most transient pops won't kill a midrange.


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## corbmonster (Jan 25, 2015)

Thanks for that link DLO13. Lots of good info in there. That actually answered a few question I was thinking about, but hadn't asked yet.


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## corbmonster (Jan 25, 2015)

The nice high end components, and even coaxial were designed to take the abuse. Would bass blockers be recommended for entry - mid level quality speakers that I would be looking at, or the average non-audiophile consumer. Be it coaxial, or components? I was always under in impression that bass blockers were a good idea for mid range speakers. Especially if you have sub(s) (which I don't, but I will).


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## bbfoto (Aug 28, 2005)

Yes. Even high-end components can benefit by using a HPF if you are running a subwoofer. And if you are using an amplifier to power your Polk DB651 6.5" mids, and that amplifier has a built-in crossover circuit (usually 12dB or 24dB per octave), you could set the amp's crossover to HPF (High-Pass Filter) and adjust it to 70-100Hz so that it will only send frequencies above that to your Polks.

Some head units/CD stereos have Crossovers that you could use as well, but the lower-end models usually will just have a XO for the Subwoofer, but you could check yours. Some of these XO's will work on both the head unit's speaker outputs and on the RCA line outputs, but you'd have to check on your particular head unit as some will only do either/or, etc.

If your amp or head unit doesn't have built-in XO's, then definitely use a Bass Blocker model that is 150hz @ 4-Ohms for your 6.5" Polk's... the Bass Blockers are just a simple capacitor that will net a shallow 6dB/octave rolloff. If it was a steeper slope, i.e. 12dB or 24dB per octave, then you could lower the Cut-Off Frequency to 70Hz-100Hz.

If you don't have a subwoofer at the moment, you will notice a large decrease of midbass when using the Bass Blockers, but they will protect your Polk's until you get the subwoofer installed.

Depending on which amp you choose for your subwoofer, it could have a good XO circuit that will send a Low-Pass (LPF) signal to your subwoofer at say 80Hz @ 12dB/Octave, and then it may also have a set of line output RCAs that use that same Frequency to send a High-Pass signal to your other amp for your front Polk DB651's. Or just use Bass Blockers for the Polks if you will not be using an amplifier for them, or if the amp doesn't have a XO with HPF.


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## corbmonster (Jan 25, 2015)

bbfoto said:


> Yes. And if you are using an amplifier to power your Polk DB651 6.5" mids, and that amplifier has a built-in crossover circuit (usually 12dB or 24dB per octave), you could set the amp's crossover to HPF (High-Pass Filter) and adjust it to 70-100Hz so that it will only send frequencies above that to your Polks.
> 
> Some head units/CD stereos have Crossovers that you could use as well, but the lower-end models usually will just have a XO for the Subwoofer, but you could check yours. Some of these XO's will work on both the head unit's speaker outputs and on the RCA line outputs, but you'd have to check on your particular head unit as some will only do either/or, etc.
> 
> ...


Thanks for that info! I do have some 150 hz bb's. My speakers are not amped yet. They might be in the future though. My plan is to pick out some components for the front, install and amp them. Once I get the components and amp wired, the 651's will go in the rear running off the HU. For now they are going in the front to tide me over till install date.

Edit: I downloaded the manual for my HU ( JVC-AHD79 ), And it does indeed look like I can have some crossover (XO ?) ability with it. It looks like (if I am reading this right). It says that there is a high pass filter, but it doesn't say if it is adjustable. It does say if I turn the sub chanel on, I can adjust the LPF, and anything below the frequency set there only goes to the sub, not the other speakers. So I'll do some playing around. I wish I could install my speakers today. But it has been raining pretty much all week long  And it's spring break  And I'm an apartment dweller. First world problems.


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## sirbOOm (Jan 24, 2013)

Use the crossover on your amplifier / head unit.


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## Victor_inox (Apr 27, 2012)

bass blocker is another name for high pass crossover.


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