Damping Factor/Slew Rate/Muddy Sound Question

[JonnieBlaze 0]

Just for background information: I use to have two 12 inch Cerwin Vega's (bought in '03, no idea was model) rated for 400w rms. They are 4 ohms, single voice coil. I have them in a sealed enclosure. It was not made to spec, but it was the closest premade box I could find to spec. I think each woofer wanted something like 2.1 ft^3 or something. Lastly, I bought a cheap amp..Boss Ripper 995. Below are the specs on the amp:

2- Channel MOSFET Power Amplifier

Power Max (2 Ohm) 500w x 4

Power RMS (4 Ohm) 260w x 4

Power Bridged: 1000w x 2

Tri-Mode

VU meters [power level]

Cooling fans

Remote subwoofer level control

Line and speaker level inputs

MOSFET power supply

Line outputs

Variable high & low pass crossovers

Fain control

Power and Protection LEDs

0~180 degree variable phase shift control

Bass Boost 0 - +18 dB

S/N Ratio: > 105 dB

T.H.D. 0.01%

Now to the issue. I remember this setup being very muddy and not very tight sounding. In my own mind, I decided it was the size of the woofers and to get a quicker tighter sound I needed something smaller that would move faster...such as 8 inch woofers. But I'd need several of those to make up for the lost surface area and excursion of the 12's. So I decided 4 eights should do the trick. But then I talked to a guy that installs system for a living and he tells me about the dampening factor and slew rate of amps. He says my boss amps lacks any good dampening and slew rate and that's why I get the muddy sound. The amp just can't recover quick enough after a hard hitting bass note. He said my Cerwin Vegas would sound much better if I just get a better amp.

So now I'm kinda stuck. I was looking at Kicker amps because they are right in my price range. To power two 8 inch woofers i was going to use one Kicker 750.1 But they dont list slew rate or dampening factor and their tech support doesnt know it either (waiting for the R&D lab to call me back) I want the best bang for my buck. I know there is always something better out there but I dont need the best of the best. I just want something that will give me the tighter bass. Suggestions?

Something else to note, on JL Audio's website (out of my price range..), their amps have better dampening factors at higher ohm loads:

>500 @ 4 ohm / 50 Hz

>250 @ 2 ohm / 50 Hz

Would this be the same for all amps? Comparing a kicker amp hooked up to a sub at 4 ohms and the same amp hooked up to a sub at 2 ohms, would the 4 ohm setup have the better feel because it has the higher dampening factor? Because if the 4 ohm load gives a tighter feel to the bass, then I wont go with a mono amp and run it at 2 ohms.....I'll get a 2 channel amp and give each sub its own channel at 4 ohms.

Sorry for the length of this post..I just really need some answers.

[///M5 2,833]

Neither idea is right.

8's won't be any quicker or faster or whatever you want to call it than 12's or even 18's for that matter. However, his slew rate comment isn't what is happening either. You have a few issues.

1- your amp is junk, you are probably driving it into clipping which surely doesn't help

2 - your box, your box, your box ---99% of all issues are install related and I am sure yours is

3 - your expectations of the CW might be a bit high although that is surely not your fundamental problem

[Thumpper 266]

with a conventional amplifier the damping factor changes drastically with

the frequency and resistance between the amp and the woofer

the ONLY time damping factor makes a real difference is if you are dealing with

an "effective" damping factor

there is only one possible way to acheive a true high effective damping factor

and that is with the use of true high current servo's

there are very few car audio amplifiers with high quality current servo's

and they are usually high priced....

I would go on line and find a used JBL/Crown BPX amplifier if you were after

seriously tight bass on a low budget...they have an effective damping factor

almost 20X higher than the conventional class D amplifier

here is an article on damping factor..pay close attention to the last paragraph

http://www.monstercable.com/mpc/stable/tec...tor_Article.pdf

[JonnieBlaze 0]

1- your amp is junk, you are probably driving it into clipping which surely doesn't help

Agreed. I need a better amp. Thats what I was asking about

2 - your box, your box, your box ---99% of all issues are install related and I am sure yours is

Again I agree. But with it being sealed and very close to the manufactor spec for a sealed box, shouldnt this have a very small effect? Seal boxes have the capability to get lower but not neccessary as loud as ported right? and they also have more tolerance for error because of the air acting as a spring keeping the sub from damage?

3 - your expectations of the CW might be a bit high although that is surely not your fundamental problem

I know they are not the best, but in all honesty I'm not too interested in making them much better. They've been out of the car for two years and they'll probably stay that way. My concern is with the new woofers. I'm still going to go with the 8's but I want to make sure I dont mess up the install this time. That why I'm looking for help with the amp decision.

[///M5 2,833]

Pick your subs before your amp...always.

8's won't be any faster than larger drivers, if that is your reasoning it is flawed.

[JonnieBlaze 0]

What I want is something that will reproduce the 80Hz to 100Hz range very accurately. This is what you feel when your at a concert and the drummer is using the kick drum. You feel it pound in your chest.

I've never been able to replicate this.

My goal was to use 8's (sundown's E8s seem to be some of the best around?...I thought the 8s would play these frequencies better without being overly loud, just accurate) and install them in the board behind the back seat of my car where the stock speakers are. I would build the sealed enclosure (or whatever box would be better to achieve this goal) under the speakers hanging down into the trunk space. That way they are not stashed in the trunk and you can clearly hear/feel them without putting the back seats down.

For anything under the 80Hz range maybe I will one day get some 12s or something and place them in the trunk.

Any suggestions for achieving this?

[JonnieBlaze 0]

I would go on line and find a used JBL/Crown BPX amplifier if you were after

seriously tight bass on a low budget...they have an effective damping factor

almost 20X higher than the conventional class D amplifier

So would this amp be something you'd suggest: JBL Amp

I just didnt think JBL was very good. I thought Kicker was higher quality than JBL. However, I just got done talking to Kicker's R&D lab and they dont have any dampening or slew rate specs. At least this JBL lists the dampening factor.

[KU40 173]

for that range midbass drivers are what you want, not subs. what are your other speakers in the car?

[///M5 2,833]

for that range midbass drivers are what you want, not subs. what are your other speakers in the car?

x1000000000

Subs playing above 50hz are suspect in the first place.

[JonnieBlaze 0]

I dont have the car yet. I'm trying to find something better on gas so I'm sure it'll be some sort of sedan...I just want to be ready for it.

Now, hypothetically, say I was putting it in my blazer. Upfront I have two 4.5" Boston Accoustics and two 6.5" Boston Accoustics. Its not very much and its all coming from the headunit but it does ok. I would love not to have subs taking up all my space if this 80Hz-100Hz was achievable without them. I'd probably still get some small 8's however just to round it all out.

So what's the story on midbass? Do they need enclosures too? What would be a good budget midbass driver? I was looking at four 8inch woofers for 240...so I guess 'budget' to me is about 60 a piece.

[KU40 173]

most midbasses made for car use don't require enclosures because they know that you'll most likely be putting them in doors, which are usually IB. But if you have the room for enclosures up front, they'll help a little. But for your blazer........hmm. you could do something like a dedicated midbass in the doors in the factory spot, then keep your 4's up in the dash to handle midrange and treble. Might not be ideal for imaging to have them separated like that, but it would likely give you the most midbass for the easiest install. You'd want to make sure and sound deaden your doors, and cover up all of the holes on the door skin (not the ones on the bottom of the door that let water drain out), as this will create a true IB situation and you'll get much better response.

You may want to measure the depth you have available in the door. Some door-mounted speakers have a problem with hitting the window on the inside. You may also want to measure outwards from the speaker location to see if you can fit a spacer in there to give you more depth behind the speaker. You'll just have to see how far you can go forward before you hit the door panel. Like in my explorer, i just made some 3/4" baffles and the extend my speakers out so that they almost touch the panel but allows them enough room for the basket and motor to not hit my window.

[Thumpper 266]

I just didnt think JBL was very good. I thought Kicker was higher quality than JBL.

um...OK.....

here have a look at this

http://jbl.com/car/team_jbl.aspx?Language=...&Region=USA

I have had 10,000 worth of kicker in one install...

not knocking but my kicker system was not even close to the SQ quality of my JBL system

[JonnieBlaze 0]

Dont they hit the inside of your door panel when you extend them out so far? Or do midbass speakers not have very much excursion?

Any recommendations on midbass drivers?

[JonnieBlaze 0]

I have had 10,000 worth of kicker in one install...

not knocking but my kicker system was not even close to the SQ quality of my JBL system

Haha...you've proved your point. I didnt know JBL was good quality equipment. For some reason I related them to equipment you'd get at Walmart. But these crown amps are starting to look pretty good to me.

[///M5 2,833]

Definitely don't knock the Crown/JBL amps they are real nice, albeit rather large.

Midbass recommendations will depend on the processing you have, the mounting location, what drivers you will use with them, and of course your budget.

[JonnieBlaze 0]

Midbass recommendations will depend on the processing you have, the mounting location, what drivers you will use with them, and of course your budget.

Budget: Around 50 or 60 a piece

Mounting Location: Don't have the car yet..so no idea. The only place upfront that I know of would be the doors. If that didnt work I guess I'd be forced to put them in the back above the rear seats.

Other Drivers: Well I'm hoping to get a couple of the Sundown 8 inch woofers. Aside from them I'm not sure what other speakers I'll be choosing for the car.

Processing: Right now I have nothing. Should I pick the drivers out first then go from there?

[KU40 173]

Dont they hit the inside of your door panel when you extend them out so far? Or do midbass speakers not have very much excursion?

Mine don't hit the panel, but like I said it's close. and they only have a few mm of excursion, not 20+ like the big subs. But of course there are drivers like the Adire Extremis that I think have something like 10 mm excursion, but like I said you just have to plan for that. I was able to use spacers because mine wouldn't hit, but you may not be able to. so that's another thing to keep in mind when figuring out the depth you can use.

[///M5 2,833]

You need to know what space you have before you can choose anything.

[DevilDriver 28]

To answer the question about what specifically causes subwoofers to sound sloppy, people look for a lot of reasons but it really comes down to what happens in the frequency domain (ie. frequency response). Flat response in the subwoofer range, especially transitioning into the midbass, is really what is key to good, even performance from your subwoofer. A common mistake people make is to allow the low frequency performance of a driver to practically swamp the response above 50-60 Hz (particularly when we consider the transfer function/cabin gain of your vehicle).

The primary negative detractors will be the inductance of the voice coil, the enclosure, the vehicle's transfer function, the power on tap, and the midrange/midbass driver's own performance. All of these things need to be managed appropriately to achieve the response you're looking for. There are secondary detractors (like mass, BL, and others) but these can easily be accounted for or even avoided if the primary detractors are taken care of.

[JonnieBlaze 0]

You need to know what space you have before you can choose anything.

I was just looking for suggestions so I can start looking on my own. I'll find out later what will fit or not..I dont even have the car yet. I just want to start looking at what you all recommend as good midbass drivers.

The primary negative detractors will be the inductance of the voice coil, the enclosure, the vehicle's transfer function, the power on tap, and the midrange/midbass driver's own performance. All of these things need to be managed appropriately to achieve the response you're looking for. There are secondary detractors (like mass, BL, and others) but these can easily be accounted for or even avoided if the primary detractors are taken care of.

As for this 'vehicle transfer function'...is this the same as the vehicle's resonant frequency or what not? If i remember correctly, is this when you take a woofer in a sealed enclosure, put it in the middle of your car, and start playing frequencies until you find the frequency that's the loudest on the meter? That would be your vehicle's resonant frequency and it's the loudest because not only is the woofer playing that frequency, but your car is vibrating at that same frequency therefore amplifying the sound?

Edited May 23, 2008 by JonnieBlaze

[JonnieBlaze 0]

Alright...

Well I found these for midbass drivers: CSS SDX7. Anyone know if they are any good (they say woofer but would they actually be midbass)? They are out of my price range, but I'm not sure what to look for so its kinda hard finding good ones. If anyone has some recommendations let me know please. I dont care about size or anything, I just want to be able to look at a a few.

Secondly, back to the top of the thread. The JBL Crown amp was suggested previously for the subs. What is another amp that has good dampening factor that would work well with midbass drivers? JL and JBL/Crown are the only companies I can find that list dampening factors....I was just curious as to some other ones.

Thanks for everyone's help so far

Edited May 26, 2008 by JonnieBlaze

[JimJ 11]

I wouldn't worry about an amp's DF, to be honest.

[JonnieBlaze 0]

really? I mean that'd be a huge relief if you're serious.

you wouldnt happen to have any recommendations on midbass drivers would you?

[JimJ 11]

I'd go on Madisound and just browse

Read some reviews on Zaphaudio.com, but I'd look at all the drivers I could in the price range.

I don't think I'd buy anything until I had the vehicle there to take measurements.

[JonnieBlaze 0]

Thanks for the help. I'm looking around a bit now just to get an idea of what my options are.

About this madisound website...are those speakers for mobile use or are they more for home audio? Or does it matter?

And no, I'm not buying anything till I know what will fit in the car I get....lol. I just want to know what's out there.