OK - Need Amp help

Thread Tools
 
Search this Thread
 
  #1  
Old 04-13-2002 | 12:14 AM
Silver_2000's Avatar
Thread Starter
|
Senior Member
Joined: Mar 2000
Posts: 6,798
Likes: 0
From: TEXAS
OK - Need Amp help

Guys -

I have a system I had professionally installed almost 2 years ago that I want more oomph from. As I started researching I am releasing the Alpine (mrvf357 ) v12 5 channel AMP I was sold doesn’t have near enough power to drive any of the speakers near their optimum.

I have a single JL 10w6 which calls for 250-300 amps RMS and the V12 is only putting out 100 watts.

I have Boston acoustics Rally RC61 components in the front and RX87 5x7's in the rear. Both sets will handle up to 80 watts each and the V12 is only feeding 30 each.

I don’t have a lot of space for separate amps but I can find a 5 channel that will drive the sub well....

The issue is that I dont understand all the terms and how they apply. ohms, bridged, nonbridged, etc etc.

Can you guys that know this stuff help me figure out the best thing to do here ???

The alpine mrd752 is looks like it puts out 75 watts x 4 and 250 watts which looks about right but it is $600 so I want to be sure before I buy...
here are the specs for the MRD752
RMS Continuous Power (Watt) (at 12.0V 20-20kHz /* 20-200Hz 0.3% THD): 4 Ohm Stereo (0.08% THD) 75W x 4 + 250W*; 2 Ohm Stereo (0.3% THD) 100W x 4 + 250W*; Bridged 4 Ohm (0.3% THD) 200W x 2 + 250W*
Geesh

Thanks in Advance
Doug
 

Last edited by Silver_2000; 04-13-2002 at 12:26 AM.
  #2  
Old 04-13-2002 | 12:27 PM
trashguy's Avatar
Senior Member
Joined: Apr 2001
Posts: 906
Likes: 0
From: staten island,nyc
im no expert,but as far i as i know
bridged is using the amp for more than channel(speaker)
ohm are the range for subwoofer setting
the lower the harder bass i think.
anyone else???
 
  #3  
Old 04-13-2002 | 12:34 PM
andrewjhaley's Avatar
Senior Member
Joined: May 2001
Posts: 518
Likes: 0
From: Houston, TX
The Alpine you've selected is perfect for the power requirements of your stereo.

Stereo - Each speaker has a different signal.

Mono- Each speaker has the same signal.

Ohm - A measure of resistance in a Voice Coil of a speaker. The higher the ohm, the more resistance in turn means less power from the amplifier. The lower the ohm means more power from the amplifier. Most amps are safe to 2 ohms. Each speaker has a rated ohm. Your really speakers are most likely 4 ohm. Almost every componet speaker, any kind of driver, are 4 ohms. Your JL w6 is a 6 ohm speaker. But it is dual voice coil, meaning you can run a wire that goes from the 5th channel of your new amp to the. Run a wire from the + lead on the amp to the + on the subwoofer, then to the - on the other side of the w6, then from that -, to the + on the other side of the sub, from that + to the - on the amplifier. This causes the resistance to be cut in half. Its also bridgeing your voice coils together. The load will be cut down to 3ohm on your amplifier. Causing it to put out more power, probably around 350 which is perfect for the w6, but it will still be very safe for the amplifier also.

Stereo vs Mono:
The terms stereo and mono are often used when referring to amplifier connections. A stereo amplifier has two independent channels, one left and one right. The left and right signals of the stereo signal are similar but not exactly the same. The two channels are used to give the audio a sense of depth. If one instrument or voice is only produced in the left channel, it will seem to originate from the left side of the listening area. If a particular sound is only slightly louder in one of the channels, that sound will seem to originate off center slightly toward the channel in which the sound is louder. If you have two speakers but supply mono signal to both of them, there will be no sense of separation or depth. If a mono signal fed to both channels of a stereo amplifier, with a speaker on each channel, the output will mono. If a stereo signal is fed to the same amp/speaker set up, the output will be stereo. If a speaker is bridged onto a stereo amplifier, the output of the speaker will be a mono output, even if the signal fed into the amplifier is a stereo signal. Even if 2 speakers are bridged onto the amplifier, the output will still be mono because the output from each speaker has the same content.


Channel - An output off of the amplifier where 1 set of '+.-' are connected.

Bridged- It it NOT necessary to bridge an amplifier to make it produce maximum power. If an amplifier is 2 ohm stereo stable (and therefore 4 ohm mono stable), it will produce the same power into a 2 ohm stereo load as it will into a 4 ohm mono load. Later, I will explain why this is.

Many people feel that they have to connect every amplifier they own in a 2 ohm mono load. These are generally the same people who have owned (and destroyed) many amplifiers. This is because very few amplifiers are capable of safely driving a 2 ohm mono load. Later, I'll explain why 2 ohms mono is dangerous to most amplifiers.

Bridging an amplifier simply means using two output terminals both of which have signal on them (there's usually one each from the left and right channels of the amplifier). It is usually done to increase the power output to a speaker or to utilize both channels of a stereo amplifier if you only have one woofer.

Ex: When 2 channels of STEREO audio output from the amp are crossed and connected doubling the power of the amplifier. It is caused by hooking the speaker wires to '+' on one channel, say the right channel, and '-' on a different channel, say on the left channel

Non - Bridged - Simply means for a 2 channel, 4 channel or 5 channel amp. That each channel will be independent of eachother. The 5th channel is usually dedicated for a subwoofer and is always a mono channel, because its just one and not 2 different channels which cause it to be stereo.
 
  #4  
Old 04-13-2002 | 12:35 PM
andrewjhaley's Avatar
Senior Member
Joined: May 2001
Posts: 518
Likes: 0
From: Houston, TX
Anything else, or something not clear, email me.
 
  #5  
Old 04-13-2002 | 10:46 PM
WaveBlaster785's Avatar
Senior Member
Joined: Mar 2002
Posts: 1,075
Likes: 0
From: MD
The alpines are nice amps because they are regulated, but 75x4 250 Watts for 600$ is REDICULOUS....Look around CBRStereo.com or onlinecarstereo.com for something that is 4 channel with a sub amp, so basically a 5 channel, kicker makes a nice amp, so does Rockford....don't pay all that money for 250 watts, heck, my head unit is almost that much wattage....Just my humble opinion, but alpine amps, while underrated are well overpriced....
 
  #6  
Old 04-13-2002 | 11:13 PM
Silver_2000's Avatar
Thread Starter
|
Senior Member
Joined: Mar 2000
Posts: 6,798
Likes: 0
From: TEXAS
I dont want to fill the truck with AMPS there is little enough space....

I dont see a multichannel amp at https://www.onlinecarstereo.com that puts 250 watts to the sub for less than 600

Rockfords 5 channel that only puts 100 watts to the sub is $589.00

JL has one that puts 250 watts to the sub for $599.00

I may be missing something or misunderstand but it looks like you have to spend that much to get decent power for the sub channel. I could get a 300 Sub amp and use the 5 channel alpine as a 4 channel but the newer high power amps will put more power to all 5 channles than what I have now...

Still confused.

Doug
 
  #7  
Old 04-14-2002 | 02:46 PM
andrewjhaley's Avatar
Senior Member
Joined: May 2001
Posts: 518
Likes: 0
From: Houston, TX
Set a budget for yourself. I dont use the rear speakers in my L at all. You could buy a nice 4 channel amp for 350 online, or you could get a 2 channel amp to just power the fronts for 250. Then buy a seperate amp for your subwoofer for another 250. All in all, set a budget for whatever you do. If you get an additional amp, youll have to take into acount wires and installation cost if your not doing that yourself. It would be totally pointless to buy a 5 channel amp and not run the 5th channel because you have another amp for the sub, big waist of money and power.
 
  #8  
Old 04-15-2002 | 10:56 PM
p_ferlow's Avatar
Senior Member
Joined: Jan 2001
Posts: 975
Likes: 0
From: W. Van., BC, Canada
If you have the space go with a 4 channel and a 2 channel or mono amp for the subs.

This way you can always upgrade one or the other to go bigger without having to trash a REALLY expensive 5 channel amp every time.
 
  #9  
Old 04-21-2002 | 08:43 AM
isaiah4031's Avatar
Member
Joined: Jan 2002
Posts: 51
Likes: 0
The alpine is a good amp as well as the others. No one says you have to run full RMS power to a speaker in order to make it perform. The 250w sub section is fine for the w6. wire it in parallel (+ from both sides of sub to amp and - from both sides to amp) giving a 3 ohm load. Not the optimum for power, but it will give the sub about 350 watts or so. The alpine amps are regulated so you get the same power regardless of voltage input.

Other amps to look into Soundstream 705, Concept, ADS
I know there isn't much room, but 2 amps will give you the flexibility you desire. A 50w x4 and class D amp for the sub. Memphis makes their studio line that is only 6in w and less than 12" long.
 



Quick Reply: OK - Need Amp help



All times are GMT -4. The time now is 07:30 PM.