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Question about amp and sub compatability

Discussion in 'Mobile Phones / Entertainment' started by Jassen M. West, Jun 9, 2004.

  1. Jassen M. West

    Jassen M. West Supporting Actor

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  2. Brad_Harper

    Brad_Harper Stunt Coordinator

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    Your amp and sub will work just fine together. Just follow the amps installation instructions and you will have no problems.
     
  3. Jassen M. West

    Jassen M. West Supporting Actor

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    thank you [​IMG]
     
  4. David.G

    David.G Stunt Coordinator

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    ah, i disagree with Brad. The 2408 only puts 300RMS at 4ohms and thats bridged. More than likely Visonik rated their amp at a 14.4v setting. Your car only puts out 12V unless you're upped it. So since its overrated i'd put it at around 250-280RMS bridged. The sub takes 450RMS so you'll under power it by almost 200RMS. Thats alot so i wouldn't expect the sub to perform at its potential. Installation is easy since you got a DVC. But i'd watch the sub cause if you underpower it you might run into problems with it later.
     
  5. Jassen M. West

    Jassen M. West Supporting Actor

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    DVC? Whats that and why does that make installation easy? I also should have all the parts in today so i'll be putting it together tonight. I don't want to shake the neighbors with it i just want to add to my enjoyment.

    thanks,
    jay
     
  6. Brad_Harper

    Brad_Harper Stunt Coordinator

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    300W is more than enough to power your subwoofer. Just because the sub is rated for 450W doesn't mean you can't power it with less. 100W would be enough in this case. Speaker wattage ratings indicate the maximum wattage the speaker can handle. So a 450W rated speaker will work from 0 to 450W. Sometimes manufacturers will specify minimum power ratings for decent sound output as powering a subwoofer with a 10W amp will not yield the greatest results.

    I have 2 infinity kappa woofers in my vehicle. There rated at 275W RMS each. I only power them with one monoblock amp rated at 300W into 2 ohms. So only 150W go to each woofer. It gets plenty loud and I have yet to drive the amp into clipping. Don't worry about underpowering your woofer with the amp you have.

    DVC stands for dual voice coil. This means that your sub has 2 voice coils. You have to wire your voice coils in series or in parallel in order to get your sub to work. In your case your sub has two 4 ohm voice coils, so if you wire them in series you will have an 8 ohm speaker, if you wire them in parallel you will have a 2 ohm speaker. In your case you have no choice but to wire the voice coils in parallel and then run the sub off of 1 amp channel. Your amp cannot handle 2 ohm speaker in bridged mode. Just hook it to the left channel speaker output of the amp then connect the left channel RCA input to your. The left channel usually has the mono bass tones. In your case a DVC subwoofer has made the installation a little more difficult.

    Hopefully this has helped you out.
     
  7. Jassen M. West

    Jassen M. West Supporting Actor

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    Thank you Brad and David, you both make great arguments either way. I'm going to try what Brad said to do. I might not have a chance to wire it all tonight but i should have my enclosure done by tomorrow. I'll post my results.
    thanks again,
    jay
     
  8. David.G

    David.G Stunt Coordinator

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    mmm....disagree with the wiring. What are you trying to do, mess with his head, just messing. I think you're looking at the 4208, but i think he said it was the 2408. Its a 2channel amp so both channels are the same. A 2channel amp only has 1 input. the amp can be wired that each channel goes to each voice coil. I don't know what you're talking about with just using the left channel. its a 2ch which means it has a 1 or 2 ch mode. You'll still use it in two channel mode and have each channel going to each voice coil. If you just plugged in the left channel either one you get a 120RMS for that channel. If you brought it down to 2ohm for that channel through the wiring up of the sub it does 225RMS. Remember you're not going to get the 600RMS they say it can do. And RMS is different from peak. You're talk about maximum wattage and if you looked at the sub i think 400RMS not peak. In car audio they usually put both peak and RMS so i'm suprised Audiobahn didn't. I actually looked at the peak power on a different website and its near 800watts. You'll under power the sub by quite a bit and it may not hurt the amp but it will hurt the sub in the long run. Rule of thumb for car audio is a amp RMS rating within 50watts of the subs RMS rating. [​IMG]
     
  9. Jassen M. West

    Jassen M. West Supporting Actor

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    David,

    Is there anything i can do with what i have then? As i have said I'm not looking to win competitions just add a little low end to my music.

    thanks
    --jay
     
  10. David.G

    David.G Stunt Coordinator

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    you will be able to use it an get pretty good response from it but depending on the sub and how each subs is made differently, the sub may run into suspension problems. When they say ???RMS it means they need that to run properly. The sub might not be covered nuder warranty if the sub is underpowered or overpowered depends on the warranty. if that doesn't really to you then you'll be ok, but don't expect the best sounding bass coming from the sub.
     
  11. Brad_Harper

    Brad_Harper Stunt Coordinator

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    David: RMS stands for Root Mean Squared and is the term used to approx the DC value of a sine wave. Now for audio the DC value lets the user know how much continuous power an amplifier can output or the cont power a speaker can handle.
    As I have said in many posts underpowering a woofer will never damage it so long as you are not getting into amplifier clipping (distortion).

    Jassen: DO NOT WIRE EACH VOICE COIL TO THE SEPERATE AMPLIFIER CHANNELS!!!!
    This in the long run could damage your speaker. What you have is a 2 channel amp (stereo) if you wire each voice coil to the seperate channels then they could receive different signals. Bass sometimes is in stereo and having the voice coil receive 2 different signals could cause damage. What I suggested is hook the voice coils up in parallel (2 ohm load) and hook the woofer up only to the left channel. The right one will be left unused. Then only hook up the left RCA preout from your deck to the amp. Left preout contains all the mono information so your woofer will receive the mono bass from the headunit.

    A DVC sub is really for installations that have multiple subwoofers because depending on how they are wired they allow you to customize the load the amp will see. Seeing as you only have 1 woofer you cannot fully utilize the amp you bought. YOu will be ready in the future if you want to add another woofer.
     
  12. David.G

    David.G Stunt Coordinator

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    man why you keep on talking about the left channel. If he does that he gets one channel of power at 2ohm. If you want to get it mono, then bridge it and wire it in series. He is running into a hard install since the amp can't go to 2ohm, but i wouldn't wire it to one channel. And with a car amp, there is no left or right channel for more bass output so i'm not sure what you're talking about. The left is the same as the right on car audio. It has one RCA input and the EQ for the amp effects both channels.
     
  13. David.G

    David.G Stunt Coordinator

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    man why you keep on talking about the left channel. If he does that he gets one channel of power at 2ohm. If you want to get it mono, then bridge it and wire it in series. He is running into a hard install since the amp can't go to 2ohm, but i wouldn't wire it to one channel. And with a car amp, there is no left or right channel for more bass output so i'm not sure what you're talking about. The left is the same as the right on car audio. It has one RCA input and the EQ for the amp effects both channels.
     
  14. brentl

    brentl Screenwriter

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    I was trying to read the PDF to see if the lowpass filtering works on both channels.

    If it does just set the low pass between 40-60Hz and run each voice coil to an amp channel and you car will rock.

    Whil it's true that if you can get and amp that matches max input of the sub there is less chance of a problem you still won't have a problem running 150 watts into this sub.

    Just be careful that when you push it you listen for distortion because you could ruin your subwoofer pretty quickly with a square sine wave.

    B
     
  15. brentl

    brentl Screenwriter

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    I was trying to read the PDF to see if the lowpass filtering works on both channels.

    If it does just set the low pass between 40-60Hz and run each voice coil to an amp channel and you car will rock.

    Whil it's true that if you can get and amp that matches max input of the sub there is less chance of a problem you still won't have a problem running 150 watts into this sub.

    Just be careful that when you push it you listen for distortion because you could ruin your subwoofer pretty quickly with a square sine wave.

    B
     
  16. VinhT

    VinhT Second Unit

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    David, I know you want to be the car guy to go to on this board, but there is some misleading information that you are giving out.

    I have never heard anyone say this. Is it common practice? Sure. Why? Just to stay safely within the thermal limit of the driver. Or perhaps because people advise others that they need to match power ratings in order to enjoy their sub. In reality, just don't go too far over what the manufacturer recommends. However, everything under will do just fine as long as you have your input sensitivities set up correctly.
     
  17. VinhT

    VinhT Second Unit

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    David, I know you want to be the car guy to go to on this board, but there is some misleading information that you are giving out.

    I have never heard anyone say this. Is it common practice? Sure. Why? Just to stay safely within the thermal limit of the driver. Or perhaps because people advise others that they need to match power ratings in order to enjoy their sub. In reality, just don't go too far over what the manufacturer recommends. However, everything under will do just fine as long as you have your input sensitivities set up correctly.
     
  18. David.G

    David.G Stunt Coordinator

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    i'm not sure you're getting it either. I don't care baout being the car audio guy. I only check this every once in a while. Most of you guys do know stuff about car audio but more of what gets by and not what is always good for stuff. For one, a 2ch amp has one set of only on set of RCA inputs. If it has two ones an output for master/copy. So yes a HU will have different RCAs for different frequencies but he's talking about plugging a RCA into the left one??? there is no left one on the amp just one RCA. If he bridges the 2 channels and run it at 40hms we'll get the full RMS that the amp can make. Running in series means running the (+) of 1ch. and the(-) of the 2ch channel. then on the sub wire it to its respective leads. But with the pair left over run a wire from one to the other. I believe thats the correct way to run it in series. it gives it a 4ohm load. Thats what he needs to do with that sub not running it off the left channel only(or the right one). he's not running it in mono with hooking it up to one speaker. its reading a 2ch @ 2ohms and you may run into problems with this since the 2nd channel isn't running also a 2ohms, not a mono at 4ohms. You are correct there is no magic number for running a speaker at but there is a number for what is good for the speaker. Running a speaker at RMS will give it the best results. Anything over or under will created different scenarios for the results. People usually try to match up the RMS ratings on the amp and sub for optimal results but since most of you are wanting optimal results and just results then underpowering it is ok. I would not do this but thats me. Both of us are more correct in certain areas, but as far as connecting it to one channel....THATS A HUGE NO! BRIDGE CHANNELS 1 AND 2 AND WIRE THE SUB IN SERIES.
     
  19. David.G

    David.G Stunt Coordinator

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    i'm not sure you're getting it either. I don't care baout being the car audio guy. I only check this every once in a while. Most of you guys do know stuff about car audio but more of what gets by and not what is always good for stuff. For one, a 2ch amp has one set of only on set of RCA inputs. If it has two ones an output for master/copy. So yes a HU will have different RCAs for different frequencies but he's talking about plugging a RCA into the left one??? there is no left one on the amp just one RCA. If he bridges the 2 channels and run it at 40hms we'll get the full RMS that the amp can make. Running in series means running the (+) of 1ch. and the(-) of the 2ch channel. then on the sub wire it to its respective leads. But with the pair left over run a wire from one to the other. I believe thats the correct way to run it in series. it gives it a 4ohm load. Thats what he needs to do with that sub not running it off the left channel only(or the right one). he's not running it in mono with hooking it up to one speaker. its reading a 2ch @ 2ohms and you may run into problems with this since the 2nd channel isn't running also a 2ohms, not a mono at 4ohms. You are correct there is no magic number for running a speaker at but there is a number for what is good for the speaker. Running a speaker at RMS will give it the best results. Anything over or under will created different scenarios for the results. People usually try to match up the RMS ratings on the amp and sub for optimal results but since most of you are wanting optimal results and just results then underpowering it is ok. I would not do this but thats me. Both of us are more correct in certain areas, but as far as connecting it to one channel....THATS A HUGE NO! BRIDGE CHANNELS 1 AND 2 AND WIRE THE SUB IN SERIES.
     
  20. Brad_Harper

    Brad_Harper Stunt Coordinator

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    Ok David I know you are just trying to help and I am sorry if my previous posts seemed condescending, but I think you are a bit confused what I was trying to say.

    In Jassen's case he has a 2 channel amp that can be bridged to mono with 4 ohms or run down to 2 ohms on each channel.

    The input signal to the amp comes from the headunit preouts. The preouts consist of 1 left signal and 1 right signal at minimum. This is why you have two RCA connectors. Higher end head units will have subwoofer preouts and maybe even front and rear preouts that can be faded. Worst case though is 1 set of preouts that are non fadeable.

    The input to a two channel amp has a left and right input (same as headunit preout). Left input gets amplified by the left channel and the right by right channel. Bridging sums both channels together creating a mono signal. Each amp channel has no affect on the other, meaning I can run a speaker off the left channel and not off the right without issue. The left signal coming from the headunit preout will contain the mono information for bass tones. So if Jassen hooks up his woofer to the left channel only with just the left RCA connected he will get the proper output. Obviously he needs to use a crossover to filter out the high frequencies.

    Because Jassen has a DVC sub his options with only 1 woofer are limited. He has to hook the voice coils up in parallel or in series. This means he will have either a 2 ohm speaker or an 8 ohm speaker. His amp cannot handle a 2 ohm bridged load and 8 ohm bridged would be very weak power wise, so his only real option is to hook a 2 ohm load to 1 amp channel for the 300W output. The right channel doesn't care that it is not being powered. A waste of a channel but there isn't much he can do without buying another sub.

    Hopefully this has cleared some things up.
     

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