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View Full Version : Active vs. Passive (specific application)?



BIG-SMOOTH
03-10-2007, 11:13 PM
I'm going to order a Memphis Belle next week and I need to order my new front stage, but I'm a bit unsure as to which route to go. The amp is rated at 75x4@4ohms or 230x2@4ohms bridged. Should I just order the raw drivers and run active with 75 watts to each speaker or order the full set with crossovers and put 230 watts to each side? Obviously I would have more control and tuning abilities with the active setup, but I'm concerned that I won't have adequate power going to the mids to really make them shine. The comps I'm looking at are the CDT M6 with drt-26 tweeters.

On the other hand, I'm still considering the ID Chameleons which are available in 2 ohm models which would allow me to put 75x2 to the tweeters and 115x2 to the mids, eliminating my concerns if I went that route.

What do you guys think? Eliminating the passive crossover on the CDT set saves me a bit of money, I just don't see 75 watts doing that midbass justice.

helotaxi
03-10-2007, 11:38 PM
You'll probably be suprised how much 75W really is on components. I would say give it a try active and then if that doesn't work for you order the crossovers.

MiniVanMan
03-11-2007, 03:27 AM
It really depends on the driver you use. 75 watts will be fine for the Seas CA18RNX. The RS180 might be a little starved though.

Also, don't worry about impedance. You can take the 8 ohm version of the Dayton RS180 and do a direct comparison with the 4 ohm, and you won't hear much of a noticeable difference.

Here's a link to explain how impedance, and speaker sensitivity actually works.

http://www.diymobileaudio.com/forum/showthread.php?t=31

For an out of the box DIY driver that will sound good with little tuning, the Seas CA18RNX, or the P18RNX are hard to beat. The CA18 is a better driver when using limited processing because it rolls off on the high end naturally, and doesn't need a low pass crossover. It's also very sensitive and will get get decently loud off your 75 watts (about 40 actual because it's 8 ohms).

If you have a head unit that has a high pass crossover so you can bandpass your mids (i.e. high pass at 80hz from head unit and low pass at 2.5k from the amp), then your speaker selection increases greatly. If your head unit doesn't, then you're relegated to using the amps crossover as a high pass (the Belle doesn't band pass that I know of), so you'll need a speaker like the CA18 that rolls off naturally.

BIG-SMOOTH
03-11-2007, 11:40 AM
I appreciate the help, but I'm not looking a different comp set. I'm basically just wanting opinions on whether or not 75 watts is going to be enough for the M6 midbass.

helotaxi
03-11-2007, 12:25 PM
Only one way to tell. What may be enough for one person may be totally inadequate for another. Just so you know, it is quite rare to actually use more than 25W on the front stage. The amp may be rated for quite a bit more but it just isn't used with music.

lrgnation
03-11-2007, 05:49 PM
the amps rating doesnt make sense to me..

75x4=300
230x2= 460

Why would it be 160 higher on 2ch if its still 4ohm. wierd..

You would probably want about 150 to each m6. and the drt-26 would be fine 75w. Like you stated. See how it is active 75x4. And if its not that good than you should get significant more power with the passive crossover.

BIG-SMOOTH
03-11-2007, 06:06 PM
[QUOTE=lrgnation;2837780]the amps rating doesnt make sense to me..

75x4=300
230x2= 460

Why would it be 160 higher on 2ch if its still 4ohm. wierd..


75x4@4ohms
115x4@2ohms
230x2@4ohms

When running a 4 channel bridged at 4ohms, each channel is seeing a 2ohm load.

BIG-SMOOTH
03-11-2007, 06:09 PM
Conventional amps work differently than the JL's that you are using in your setup. Ideally I would love to run a JL Audio 450/4 for an active front stage and a 1000/1 for the sub(s), but the best price I've been able to find from an authorized dealer was $1200 for the pair which is a bit more than I care to spend right now. That would give me...

75x2 to the tweeters
150x2 to the mids
1000x1 to the subs

Would be perfect if I had the budget for it. :(

mattmcss
03-11-2007, 06:10 PM
I will be running a belle just like you in my next setup, with the cdt M6 mids and Es-01 tweets, but i'm running them passive through their x-overs. So they will be bridged, I hear the M6 is a strong midbass performer so I'm opting to give them more power.

BIG-SMOOTH
03-11-2007, 06:12 PM
I will be running a belle just like you in my next setup, with the cdt M6 mids and Es-01 tweets, but i'm running them passive through their x-overs. So they will be bridged, I hear the M6 is a strong midbass performer so I'm opting to give them more power.

I'm thinking that is probably the best option. Slightly less tuning abilities and a bit more money in exchange for quite a bit more power.

ngsm13
03-11-2007, 06:20 PM
CDT Makes EXCELLENT xovers, designed very well for their drivers. And, ya know... they would know best ;).

nG

BIG-SMOOTH
03-11-2007, 06:47 PM
CDT Makes EXCELLENT xovers, designed very well for their drivers. And, ya know... they would know best ;).

nG

I'm sure the crossovers are of high quality, but if going active didn't have an advantage over them I'm sure the guy I'm buying them from wouldn't have recommended buying just the raw drivers since it means a smaller sale for him. Plus he runs active in his personal car using CDT comps. djdilliodon is the dealer i'm referring to.

ngsm13
03-11-2007, 06:52 PM
Indeed.

Just letting you know that CDT makes particular well designed xovers.

I know Don, have done business and pointed business his way for years and years.

nG

BIG-SMOOTH
03-11-2007, 08:59 PM
Indeed.

Just letting you know that CDT makes particular well designed xovers.

I know Don, have done business and pointed business his way for years and years.

nG

Yeah, I've dealt with Don before also. Bought a set of HD-642 comps off him a few years ago, but I sold the vehicle before I ever got to install them. He's definitely a good guy to deal with. I had him on AIM for over an hour the other night going over all my options. Not too many dealers would spend that kind of time with someone for a $280 sale.

I'm just going to go with a passive setup. I have no intention of competing with the truck so the super fine tuning really isn't THAT necessary anyway. I guys I'll have to get ahold of Don again and see how much extra for the crossovers.

lrgnation
03-12-2007, 12:20 AM
Conventional amps work differently than the JL's that you are using in your setup. Ideally I would love to run a JL Audio 450/4 for an active front stage and a 1000/1 for the sub(s), but the best price I've been able to find from an authorized dealer was $1200 for the pair which is a bit more than I care to spend right now. That would give me...

75x2 to the tweeters
150x2 to the mids
1000x1 to the subs

Would be perfect if I had the budget for it. :(


thats what i started thinking. would be a 2ohm load. got it now!

mattmcss
03-12-2007, 11:18 AM
Don hooked me up a sweet deal with the ES-01 tweeters with xovers and the M6 mids, ask him about that combo if you haven't already picked something up.

BIG-SMOOTH
03-12-2007, 03:51 PM
Don hooked me up a sweet deal with the ES-01 tweeters with xovers and the M6 mids, ask him about that combo if you haven't already picked something up.

I want to be able to mount them as a braxial so that wont work for me.

BIG-SMOOTH
03-12-2007, 03:53 PM
I talked to Don again and he swears that 75x4 running active is more than enough for the M6's so I guess I'll try it out that way and if it doesn't seem adequate I can always order the crossovers later.

azula
03-12-2007, 04:32 PM
what's the difference between active and passive? pardon the newbie question....lol

Megalomaniac
03-12-2007, 04:39 PM
what's the difference between active and passive? pardon the newbie question....lol

simple answer is:
active is crossover before the amp
passive is crossover after the amp

azula
03-12-2007, 04:53 PM
simple answer is:
active is crossover before the amp
passive is crossover after the amp



that does make sense, thanks man

helotaxi
03-12-2007, 06:17 PM
The above explanation is part of the answer but not always the case. Active filtering is always going to be before the amp but passive may not always be after it. Active filtering requires power input because it uses some kind of powered circuit to do the filtering. Most use op amps. Passive filters can be used at any time on the signal and use passive components (caps coils and resistors) to achieve the filtering. Preamp passive filters aren't very common though.

alphakenny1
03-12-2007, 06:29 PM
what's the difference between active and passive? pardon the newbie question....lol

read the sticky's ;).