Bass blockers

JetMech

I just installed a pair each of DB461 and DB691 speakers in my car. The fronts sound pretty bad if any volume is sent to them. I understand a set of bass blockers will help them out but don't know which ones I would need. Are the values of the bass blockers related to the lower end of the speaker's frequency response range?

exalted512

The values of the bass blockers are related to what frequency it will start cutting out the bass.
-Cody

ben62670

An active XO is better. The capacitor style uses cheap caps that have a negative effect on SQ.
Ben

JetMech

SQ=Sound Quality?

The crossover is an idea...

Anyway, since that speaker's range is 75Hz-22kHz, do I want to filter everything below 75Hz, be it with a crossover or a blocker?

ben62670

Yes SQ is sound quaility. 80hz, and above would be a good XO point.

JetMech

Cool, thanks for the helpful info. I'm off to look at crossovers!

awe-d-o-file

To best help you we need to know what is powering these four speakers. Also I assume you have a sub, what's powering that and do you have an independent volume or level control for the sub? What you should do is leave the head unit bass controls close to flat (don't crank the bass) and the loudness control off, this way you'll be less likely to overdrive the four speakers with bass they really can't handle and shouldn't be trying to produce anyway. This will allow the amp driving them to play louder and clearer, bass uses the most power. Then adjust the subs volume/level so you have a bass level that you like. (if you have a sub)

Bass blockers, which are a crossover of sorts, can work fine if you are powering the four speakers from a head unit or an amp w/o a built in crossover. Bass blockers are just a non-polarized electrolytic capacitor. You can buy caps for a lot less money than Bassblockers at places like parts connection who I believe also sells bass blockers. You said the speakers are rated to go down to 75hz. A crossover for 75hz doesn't stop or eliminate from 74 and below. It reduces the sound below 75 at 6db per octave in the case of a bass blocker/ cap which is referred to as a first order crossover. So at 37.5 the sound is only 6db lower and so on. An octave is half or double of a given frequency. You really want to remove the
bass so I would say try at least 100hz or even higher if you're powering them from a head unit only. Here is a chart to select the right capacitor value for your needs.



Freq / cap value in microfarads
75 531
80 497
85 468
100 398
120 331
125 318
150 265

4 OHM


75 265
80 249
85 234
100 199
120 166
125 159
150 133


8 OHM

Note 8 ohm values are half of 4 ohm values- 50V rated caps will be fine, 100V only if you have a very high powered, high dollar amp


Good luck!!

JetMech

Right now the haead unit is stock and I was planning on replacing it soon but that may have to wait a couple months. In the meantime I ordered some 600Hz bass blockers. I don't have a sub yet and am not sure if I will. The car is a 1996 so I don't know how much I want to put into it.

ben62670

600 is way to high!

JetMech

That's what the guy at Crutch recommended. I see them as temporary anyway until I get a better head unit.

ben62670

The guy at cruchfield was way off. Are you sure that they are not 60hz?

JetMech

Nope, he said 600. I don't even see any that low on their site. Here is what it says under the product info:

If you like it loud, protect your speakers from bass distortion and enjoy cleaner sound with Bass Blockers. Each Bass Blocker handles up to 50 watts RMS with a 6 dB per octave roll-off. You'll find some general guidelines below for matching Bass Blockers to speaker size. For smaller speakers (3-1/2"s, 4"x6"s, 4"s), the 600 Hz Bass Blockers work well with low-powered systems, while the 800 Hz Blockers are a better choice for high-power applications.

Speaker Size Cut-off Frequency

6-1/2", 5"x7"/6"x8" — 150 Hz
5", 5-1/4" — 300 Hz
3-1/2", 4", 4"x6" — 600 Hz (low power)
3-1/2", 4", 4"x6" — 800 Hz (high power)

These models do not have quick-slide connectors. Cut-off points are at 4 ohms. If you use 8-ohm speakers, the cut-off point is half the listed frequency.

ben62670

Polk's are a little better than needing a 600hz bass blocker. 150 maybe, but even that is way to high in my book.
Here are the specs for your speakers
Overall Frequency Response 75Hz-22kHz
Nominal Impedance 4 ohms
Power Handling (continuous) 40 w
Power Handling (peak) 120 w
Efficiency 91 dB
I am telling you the guy at crutchfield got dropped on his head;)

JetMech

Haha, that's funny!
Yeah, they seemed high to me too. But I took the guy's word for it...
Like I said though, they're only temporary so I'm not that upset.

ben62670

Well you still have the backs for fill. Are the 4x6's in the dash, or door?

JetMech

In the dash. It's a 96 Buick Century Wagon and the 6x9s are wayyyy in the back in the liftgate. The front doors have those map pockets in the bottom so if I'm lucky I could put a 3" max speaker in each front door...

ben62670

With the Polk's I would go with 150hz bass blockers, and go a little lower if you amp them. I should clarify things just a little on the bass blockers. The chart he was reading is just one chart, and doesn't apply to all speakers. If you have some old crappy worn out paper cone drivers 600 wouldn't be that unreasonable. Also being in the dash it raises the XO point a bit. Its been a while since I have been into the car gear, but I think 150hz would be good for the dash especially seeing your 6x9's are so far back, and most likely blocked by something before it gets to your ears. Hopefully others will chime in.
Ben

JetMech

I was going to change my order but they shipped already. I'll just have to deal with them for a month or so. No biggie.

ben62670

Well stick around. I am sure others will chime in Cody, and a few others really know their stuff in car audio. They can help with future upgrades.
Ben

JetMech

Oh I will...cuz I'll have plenty more questions when that happens.

ben62670

All right bro. Take it easy, but take it!
See you around.
Ben

exalted512

Its still a 4x6. While I think 600Hz is high, especially for my tastes, its not way off base. I would recommend at least 200Hz.
-Cody

ben62670

exalted512 wrote: »

Its still a 4x6. While I think 600Hz is high, especially for my tastes, its not way off base. I would recommend at least 200Hz.
-Cody

The man the myth the legend:D
Would this also pertain to an active XO?

Jeff Beaird

exalted512 wrote: »

Its still a 4x6. While I think 600Hz is high, especially for my tastes, its not way off base. I would recommend at least 200Hz.
-Cody

Don't you mean ... Way off BASS..?:D

exalted512

ben62670 wrote: »

The man the myth the legend:D
Would this also pertain to an active XO?

I'd recommend you invest in better speakers before a deck with active XOs;)
-Cody

JetMech

Jeff Beaird wrote: »

Don't you mean ... Way off BASS..?:D

:eek: Wow, that was LOW!

exalted512 wrote: »

I'd recommend you invest in better speakers before a deck with active XOs;)
-Cody

Better speakers? I thought these were pretty good.

exalted512

Theres no such thing as a good 4x6
-Cody

JetMech

exalted512 wrote: »

Theres no such thing as a good 4x6
-Cody

Good point, but that's all that will fit in the front. BUT, I think I can fit a 6" in each of the back doors so maybe that will help.

Installer4life

The DB series is a good speaker and if you don't want to spend a lot of money on custom installation then these will do. If you upgrade your headunit make sure and get one with a built-in high pass filter. These are usually 12db/octave slopes and allow you to pick from 3 or 4 frequencies. This is much better than the Bass blockers (and I agree 600hz is way to high). It will protect your speakers but at a sacrifice of sound quality. Forget putting speakers in your rear doors if you want to install them in any door make sure its the front doors.

sponger

I'm going to have to agree with other responses in that bass blockers are not the answer.

If anything, it sounds to me like they're probably underpowered, as is the case with most after market speakers running off of head units.

That is, I'm willing to bet that if you sealed your front doors with sound deadener, installed a modestly powered amplifier and ran the speakers full range, they probably would sound a lot better than they do right now.

On the other hand, if you installed an amp, you could then take advantage of the high pass filter that is built into most stereo amps.

So, get some brown bread or dynomat or whatever and seal the front doors. Then install an amp. Might as well get a 4 channel amp so you can send adequate power to those 6x9's.

You will hear a phenomenal difference in sound.

JetMech

Would sealing the front doors do any good if I don't have any speakers in them? I was only considering adding speakers in the rear doors because I don't have any place to put them in the front doors. And yes, the bass blockers ARE blocking too much of the bass IMO, but they are better than what I had and will suffice until I get a decent head unit. Once that better head unit is installed, the bass blockers will come out.