: 350w @ 2 ohm and 175w@ 4 ohm



cl1986
03-11-05, 09:02 PM
I have an Alpine MRD 301 mono sub amp and an Infinity Kappa Perfect 12.1 4ohm single voice coil.

If i had bought a DVC and wired it to 2 ohms, would this be better than my current setup??

If i buy another Infinity 12.1 and wire them in parallel @ 2 ohms would this be better than the single speaker DVC. Obvoisly it would have to be with more air movement.

If the DVC is better than the single, why are the DVC cheaper, i guess thats why i stayed away from DVC, i thought they were not as good.

maydog
03-12-05, 12:12 AM
If I understand you correctly you planned on wiring both voice coils on the DVC unit in parallel to achieve a lower reactance?

Wiring the coils in parallel will drive down the reactance allowing the amplifier to drive more power to it (if it is 2 ohm stable). But this is probably not as an effective setup as having 2 4 ohm speakers in parallel simply because of the larger effective area of the cones, it will draw the same power but be more efficient and linear (requiring less travel) than a DVC setup. The DVC will be better for space and cheaper as you said. If space is an issue and you want linearity you could try an isobaric setup.

skides1
03-12-05, 04:48 AM
If your amplifier is 2-ohm stable (for real) I say go with the DVC. Alpine's were not noted for high-current useage last time I checked but that could have changed. I used to run a 50x4 Precision Power Pro amp at less than .5 ohms which could juice over 1000 watts continuous for about 2hrs before we either threw up or thermal grease fumes overwhelmed us.

cl1986
03-12-05, 11:57 AM
The MRD-M301 amplifier owes its responsive power output (350 watts with a 2-ohm load) and clean signal response to lightning-fast MOSFET power supplies. The built-in Bass Engine© digital signal processor allows you to shape your own custom sound with a level of fine-tuning previously found only in Alpine receivers. With Bass Engine, you can:

adjust the subsonic filter from 15-50 Hz (in 5 Hz steps) to eliminate ultra-low bass which your sub wastes energy trying to reproduce;
use the digital parametric EQ (which allows you to control the width of the equalization curve, as well as the center point) to improve overall sound;
fine tune time correction, phase, and 3-level bass compensation to maximize the quality of your bass.
As if that weren't enough sound-shaping power, the Bass Compensator feature enhances low-end definition with Alpine's exclusive MediaXpander techology — used in their receivers to optimize playback of compressed media files.

175 watts RMS x 1 at 4 ohms (CEA-2006 Compliant)
350 watts RMS x 1 at 2 ohms
2-ohm stable
MOSFET power supplies
Bass Engine® features:
low-pass digital crossover, 30-200 Hz, 12 or 24 dB/octave
variable subsonic filter (15-50 Hz in 5 Hz steps)
parametric EQ variable from 30-160 Hz
Bass Compensator enhances low-end definition
top-mounted controls with digital readout and cover
speaker- and preamp-level inputs
gold-plated terminals
requires 8-gauge power and ground leads — wiring and hardware not included with amplifier
9-9/16"W x 2-9/16"H x 10-5/8"D
warranty: 1 year

Oh, like i stated i have a 1 single 4ohm voice coil sub. Your saying i would have been better off with 1 dual voice coil sub and wire it to 2 ohm?? The DVC sub was about $30 bucks cheaper and i didnt know you could wire it to 2 ohms until now. So i wasted $30 huh??

Or i could always buy another kappa perfect 12.1 but would the amp have enough power to drive two speakers, im thinking this woudl put about 175w on each then, right now i have 175w on one due to the 4 ohms. Does that make any sense??

I was thinking before i would have to buy another MRD 301 to drive the other one, but that would also only give me 175w on each. I just thought two amps and two speakers would be better than one amp and two speaker, but i guess not. The amp is mono only.

When wiring the sub 2 ohm, does it do anything to the sound of the bass??

maydog
03-12-05, 12:14 PM
Silly marketing material, everything uses mosfet power supplies nowadays... anyway.

You can drive both speakers with the one amp. The sound would likely be better than one DVC speaker and one amp. Basically the power output of the amp will be evenly divided between the speakers provided that they are evenly matched. What you will lose by going to higher power levels on one amp is accuracy of the reproduction, probably not an issue (or even noticable) as it sound like you are looking for loudness. It will also run hotter, which could be an issue depending where it is mounted.

cl1986
03-12-05, 12:19 PM
yeah Kmart stuff has mosfet supplies, LOL.

So will they sound any different at 2 ohm?? or hit different or just be louder and better and i wasted money on a single voice coil??

D148L0
03-14-05, 11:58 AM
Silly marketing material, everything uses mosfet power supplies nowadays... anyway.

You can drive both speakers with the one amp. The sound would likely be better than one DVC speaker and one amp. Basically the power output of the amp will be evenly divided between the speakers provided that they are evenly matched. What you will lose by going to higher power levels on one amp is accuracy of the reproduction, probably not an issue (or even noticable) as it sound like you are looking for loudness. It will also run hotter, which could be an issue depending where it is mounted.

:yeah:
You know what you are talking about, maydog. I hope you can stick around and help others. This section could use members like you.

cl1986
03-14-05, 08:15 PM
Oh, so it will be more accurate with one speaker than two hooked up to get 2 ohms.

I am totally confused on ohms. I thought i knew what was going on.

Isnt ohms a measure of resistance? How would hooking up two speakers cause less resistance, hence 2 ohms??

I guessing its less resistance but more power or amperes used??

maydog
03-14-05, 11:33 PM
Technically speaking, the reproduction will be more accurate at lower power levels. You may hear audiophilies talk about total harmonic distortion, the hotter the amplifier and the closer the output runs to the rails the more distortion occurs. Realistically, if the amp can handle 2 ohms you will not notice any difference in sound quality, the distortion would really have to be analyzed by instrumentation to tell.

Now for the speakers, driving the same power level into one speaker vs 2 - the one speaker will travel further. The further the speaker traveles from the center the more resistance it will meet which again causes distortion. But again, in a car enviroment only the audiophile types will probably say that they can tell the difference.

Long story short - you cannot go wrong with any setup. My preferred option would be to use 2 speakers hooked in parallel driven from the one amp. This leaves the option later to add another amp and drive the speakers separately when the hearing loss kicks in.

maydog
03-14-05, 11:42 PM
Oh, so it will be more accurate with one speaker than two hooked up to get 2 ohms.

I am totally confused on ohms. I thought i knew what was going on.

Isnt ohms a measure of resistance? How would hooking up two speakers cause less resistance, hence 2 ohms??

I guessing its less resistance but more power or amperes used??

You can hook the speakers up in two different configurations. If you consider the coils to have a + and - terminal then you can either hook them up to the amp like:

series amp+ <-> + - <-> + - <-> amp-
parallel amp+ <-> ++ <-> -- <-> amp-

Not a very good diagram I understand, just hook + to + and - to - and the effective reactance of the coils (ohms is used for simplicity) comines to 1/2 the original value.

Think that at a given voltage (drive) level a given amount of current will pass thorugh the speaker coil, now you have two coils hooked up to that drive. Each speaker will have the same current, so the supply is driving 2x the current at a given voltage so the effective resistance seen by the amp is 1/2.

If the speakers were to be hooked in series, then the voltage driving each is halved and the current driving them is reduced resulting in a larger effective resistance.

cl1986
03-15-05, 12:24 AM
awesome!! someone finally understands my question and answered beautifully.

Thanks man.

skides1
03-19-05, 01:56 AM
Lets educate ourselves shall we? http://www.caraudiomag.com/specialfeatures/0111cae_anatomy/index.html
Hey maydog,
why do you say low power=better sound? That is not actually true- I have a Harmon Kardon amplifier that is rated for only 45watts per channel @8 ohms and wieghs 60lbs (hence perception of low power). High end equipment is rated lower in the manual to achieve a low thd (total harmonic distortion) with super clean sound. My HK really puts out much more and is durable to 1 ohm = 500 watts, but the thd goes up exponentially. The baddest amplifier for high current (low resistance) usage is Rockford Fosgate. I have seen a 25x2 produce 300x2 @2ohms on a bench. An IASCA(international autosound competition association) cheater secret. Just like stated earlier:

Amp a = 100x2@8ohms
200x2@4ohms
400x2@2ohms
800x2@1ohms (this will smoke almost ANY cheap amp)
1600x2@.5ohms
3200x2@.25ohms (this is only possible with 5 4ohm or 10 8ohm parallel per channel and is common with competition cars trying to win a 100 watt class- Pioneer, Alpine, Audiobahn, doesn't even come close to cutting the mustard )

skides1
03-19-05, 02:54 AM
http://www.the12volt.com/installbay/forum_posts.asp?TID=48298&KW=parallel Found some great info sites:
http://www.the12volt.com/ohm/page2.asp
Check the parallel calculator:http://www.the12volt.com/caraudio/boxcalcs.asp#par

D148L0
03-19-05, 02:57 AM
That is a great site. I have been a member for about 2 years... I have recommended and linked it several times here.

D148L0
03-19-05, 03:08 AM
3200x2@.25ohms (this is only possible with 5 4ohm or 10 8ohm parallel per channel and is common with competition cars trying to win a 100 watt class)

Not true. I can give you an unbelievable amount of speaker configurations that would yield the same resistance. As a matter of fact, a few years ago there was this demo at one show (I don't remember the brand) where a single amp was pushing soemthing like 32 speakers. Lesson? Ohms are not everything...

skides1
03-19-05, 03:19 AM
That was just an illustration only was the wrong word to use. Your right- there are many configs that can do this. 10 8ohm drivers ranging in size from 18" to .25" with each only using it's frequency specific power, will still net around 8 ohms total .had 16 speakers on one amp netting close to .5 to 1 res before. I agree ohms are not everything- a 100 watt Jensen with a 14ga power wire, and 10amp fuse will fry or not even turn on @.25 ohms but a 200 watt ppi with a 4ga power wire, 120amp fuses x2, two 6 inch custom fans installed in the amp, 15.5volt stinger regulated power supply could push close to 1600 watts @ .25 for about 45 min before the fire department shows up.

skides1
03-19-05, 04:17 AM
Here it is:
1-50x4@4ohms high current, cooled amp, 4 ga power
2-4 4ohm DVC subs wired parallel to 2 channels of amp netting 1ohm (mine spec'd @ .5 to .8) and around 300x2rms from 15hz to 70.
3 4 -6.5 Quart midbass, 4 4 inch mids, 4 Quart dome's (2ohm-Ithink) much like this set times two: http://www.mbquart.com/2003/en_US/products/prod_detail.asp?isArchive=true&cat=&series=premium%20series&strt=1&model=PSC+316 custom crossovers equals a crippler.

cl1986
03-19-05, 11:16 AM
http://www.the12volt.com/installbay/forum_posts.asp?TID=48298&KW=parallel Found some great info sites:
http://www.the12volt.com/ohm/page2.asp
Check the parallel calculator:http://www.the12volt.com/caraudio/boxcalcs.asp#par

Thats some pretty cool calculators.

But i only get about half of them to give me a correct answer. What power number do u use, max rms, or what.

I have a digital amp reading on my amp and have seen it at 12 amps before. I plugged this into the one equation along with the 175w it can do and got like 1.2 ohms or something. I know the calcs dont lie, whats changing or going on there?

The other i put in 12 amps and 14.4V and that gave me the 172w that i was expecting.

cl1986
03-19-05, 11:21 AM
oh, one more question.

Two seperate speakers, if you go switching the wiring on the speaker they cancel out each other and result is very little bass produced. How does a DVC not cancel out the bass in the same way?

wouldnt two subs in series do the same thing and cancel out or do u invert one in the box and let the magnet stick out? This would make sense, but why woudl anyone want 8 ohms??? Really cheap amp??

maydog
03-19-05, 04:22 PM
Lets educate ourselves shall we? http://www.caraudiomag.com/specialfeatures/0111cae_anatomy/index.html
Hey maydog,
why do you say low power=better sound? That is not actually true- I have a Harmon Kardon amplifier that is rated for only 45watts per channel @8 ohms and wieghs 60lbs (hence perception of low power). High end equipment is rated lower in the manual to achieve a low thd (total harmonic distortion) with super clean sound. My HK really puts out much more and is durable to 1 ohm = 500 watts, but the thd goes up exponentially. The baddest amplifier for high current (low resistance) usage is Rockford Fosgate. I have seen a 25x2 produce 300x2 @2ohms on a bench. An IASCA(international autosound competition association) cheater secret. Just like stated earlier:

Amp a = 100x2@8ohms
200x2@4ohms
400x2@2ohms
800x2@1ohms (this will smoke almost ANY cheap amp)
1600x2@.5ohms
3200x2@.25ohms (this is only possible with 5 4ohm or 10 8ohm parallel per channel and is common with competition cars trying to win a 100 watt class- Pioneer, Alpine, Audiobahn, doesn't even come close to cutting the mustard )

You say I am wrong about low = better sound? Then whay do you also say that - "High end equipment is rated lower in the manual to achieve a low thd (total harmonic distortion) with super clean sound." That is what I was getting at. For any given amplifier, its output will be more linear abound is bias point, low deviations from that point (low power) are much more linear than large deviations (high power).

Now if you want to just be redicuously loud - just wire up a bunch of matched speakers in parallel (in the proper enclosure of course). Wire up a bunch of batteries in parallel use a large copper bus to an amp and throw the amp in liquid nitrogen.

I am glad that you can find an online calculator helpful, personally I do not need one, I have designed enough amplifiers (not car audio) to understand what is going on.

Your table is not really true either, the higher you go in power levels, the less efficient your supply within the amplifier will be, eventually it will start to experience voltage droop and really mess with the sound. In a perfect world it would be linear, but not here.

cl1986
03-19-05, 04:42 PM
Lets educate ourselves shall we? http://www.caraudiomag.com/specialfeatures/0111cae_anatomy/index.html
Hey maydog,
why do you say low power=better sound? That is not actually true- I have a Harmon Kardon amplifier that is rated for only 45watts per channel @8 ohms and wieghs 60lbs (hence perception of low power). High end equipment is rated lower in the manual to achieve a low thd (total harmonic distortion) with super clean sound. My HK really puts out much more and is durable to 1 ohm = 500 watts, but the thd goes up exponentially.



No the HK rating is always done in rms per channel and probrably at 8 ohms. Others just use the max output and get rated at like 200w per channel. I dare u to buy some 45w max speakers and hook them up to your HK. Although it would be funny!!

I just bought a 700w MRD-301 from alpine. It actually puts out only 150w at 12V. Theres a big difference between 700w and 150w. But it is sold as 700w. To me, they should all be sold as 150w and same with speakers, no one goes by the max anyway.

Your argument doesnt make any sense anyway. Someone always makes something bigger and better. You could get a cheap amp and let it draw 10 amps of power and let it produce 50w, and then get a giant amp turn the gain way down and still let it draw 10 amps, and the 100w that it makes will sound better and less distorted than the cheap one. I didnt go through the numbers but u know what i mean.

What maydog means is if you use "common sense" the lower level will be better. Not sure if you have any of that.

The wattage thing is like a 5hp shopvac, ya right, id like to see the motor cut my grass thats 2 feet tall, not going ot happen. I think those shop vac motors produce less than a third hp.

D148L0
03-19-05, 05:18 PM
Thats some pretty cool calculators.

But i only get about half of them to give me a correct answer. What power number do u use, max rms, or what.

I have a digital amp reading on my amp and have seen it at 12 amps before. I plugged this into the one equation along with the 175w it can do and got like 1.2 ohms or something. I know the calcs dont lie, whats changing or going on there?

The other i put in 12 amps and 14.4V and that gave me the 172w that i was expecting.
It is not a good idea to use 14.4 V in your calculations. A lot of brands use that value to increase their wattage ratings, but in real world applications you will rarely see 14.4 V. The best thing is to use a multimeter and read the actual output.

maydog
03-19-05, 05:19 PM
I did not mean to jump on anyone so I am sorry for any offense. I was crabby since I had just spen 3 hours underneath a dripping, snowy, STS on a cold garage floor replacing sway bar bushings. A shower and snack have changed my outlook.

Seriously, I am surprised that any amp would be derated by a factor of 100 or more, unless it was intentional done so for competitioun uses as you speak of. THe dc-dc converter within the amplifier uses inductors which saturate at high current levels and the output drive mosfets have a current limit as well. Derating is common to maintain sound quality levels and reliability of a product. But designing something to handle 100 times the current of its advertised / intended use is rediculous and highly cost prohibitive.

cl1986
03-19-05, 06:16 PM
It is not a good idea to use 14.4 V in your calculations. A lot of brands use that value to increase their wattage ratings, but in real world applications you will rarely see 14.4 V. The best thing is to use a multimeter and read the actual output.

My car also has a digital votage reading and it is always at 14.4V or withing .2 volts, so how do u mean in "real world", i thought the gauge was real world?? the amp has the meter also, and reads 14.4V when the engine is running, but that is real world, i mainly listen to my car stereo WHILE driving. Why else would u have a car stereo??

No, he is right, Harmen Kardon recievers are usualy like 35w or 45w per channel. Hes talking about home stereo reciever though. The almost are "de-rated". I almost bought one, but they were UGLY, so i bought the sherwood reciever that is made by same company, less quality amp, and is rated at 85w per channel. That 85w shook my whole house when hooked up to the home theatre sub system.

Still dont know why they dont make something like a home theatre sub with 5.25" speakers and get the same bass as a 12" car speaker, NE1??

skides1
03-24-05, 10:15 PM
I definatly was not trying to argue, just debate. I enjoy the opportunity to talk about this stuff because 99.9% of the people I spend my day with don'ta clue plus pursuit of the perfect system (home and car) is my hobby. The H/K I have may be ugly but I have never seen a reciever that at +10db (boosted) source attenuation has zero noticable amplifier clipping (distortion). On the statement about my calculations regarding the PPI and Quart setup: That was an IASCA competion vehicle and a launching pad the head of R&D for the company Q-forms and let me tell you, It was capable of winning an SPL and sound quality competion with a few adjustments.

skides1
03-24-05, 10:25 PM
cl1986,
On the real world voltage: measure it with your A/C on max, your rear defog on, High beams on, heated seats and your wipers on high- then tell me you get 14.4volts. An amp which is specd out @14.4 is actually cheating on RMS ratings (or prob doesn't have a regulated power supply) because such amps energy output is directly related to the voltage supplied. Regulated supplies will put out the same from 11-16v. read(stable).

skides1
03-24-05, 10:56 PM
Maydog,
On the lower power better sound- I was just trying to say that all these factors are objective- meaning: I don't put any trust into the mfg ratings. Whenever I buy amps, I either want 1. a serious spl monster where durability doesn't matter (highly unstable-unregulated) or to squeeze every bit out of what I have,(Rockford, US amps, PPI) 2. A durable 20yr lifespan product with spectacular sound quality (sorry to say-Bose, Mcintosh, H/K, Xtant) 3. an amp for my girlfriend-. (Pioneer, Sony, etc.) Just my opinion.

skides1
03-24-05, 11:31 PM
Check out these mfg's: http://caraudiomag.com/specialfeatures/0202cae_amp/

cl1986
03-25-05, 09:51 AM
cl1986,
On the real world voltage: measure it with your A/C on max, your rear defog on, High beams on, heated seats and your wipers on high- then tell me you get 14.4volts. An amp which is specd out @14.4 is actually cheating on RMS ratings (or prob doesn't have a regulated power supply) because such amps energy output is directly related to the voltage supplied. Regulated supplies will put out the same from 11-16v. read(stable).

That doesnt make any difference, ive had fan on high, heated seats on, all that, it still is 14.4V, my alt in my eldo is a delco 120 amp and i had it on a machine it produced over 150amps while pulling about 8 hp. Ive never seen my voltage lower than 14.2V except after my battery was drained dead in the alignment shop, after a couple days it went back up to normal. Basically the alt is more than capable of working fine even with everything on. But who in the world would have heated seats and A/C running at the same time?? Thats about the only two things that really draw power, everythign else is minimal. Wipers, hardly any power. But i know what ur thinking, but it just doesnt matter.