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Old 3rd October 2005, 19:02   #16
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Default DVC sub on two channels of amp

Guys,
Can I connect a single DVC sub with one coil on one channel of amp ( say left) and anonther coil on other cahnnel of amp independently.

E.g.

instead of bridging the amp let it deliver the juice seprately.

Are their problems associated with it. Will the o.P reduce or increase. is the physical inertai of sub is better handeled being on independent channels or both voice coils drive the sa,e diphram so the load on diaphram is increased with one coil driving it in and another out.


And most imp. Will it burn out in such a case or can i experiment and see..
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Old 4th October 2005, 00:13   #17
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thanks guys... I've been using photobucket which I guess doesnt have a thumbnail option. Imageshack seems to be better for large pics.... again, thanks
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Old 4th October 2005, 10:04   #18
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Quote:
Originally Posted by pranil
Guys,
Can I connect a single DVC sub with one coil on one channel of amp ( say left) and anonther coil on other cahnnel of amp independently.

instead of bridging the amp let it deliver the juice seprately.
..
ofcourse.

lets consider 3 cases (assuming each coil is 4 ohms and 2 channel amp).

1. DVC sub each coil to one channel. Each channel "sees" 4 ohms. amp is very safe. Sub is run a bit lower sensitivity.

2. DVC sub both coils in parallel (2 ohms) then amp is bridged and sub is connected to amp. amp sees an "effective impedance of 1 ohm per channel". Amp will run hot. lesser amps will shut down or blow up at higher volumes. At lower volumes and short durations (for testing) the amp wil heat up but should be safe for a bit. In my days there used to be a company called Precision Power tht built amps that could be safely used at 1 ohms. I am told that Tru Tech amps are also capable of this.

3. DVC sub both coils in series so the sub is now 8 ohms. amp brideged. each channel of the amp sees 4 ohms. the amp will run as safe as option 1.
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Old 4th October 2005, 11:52   #19
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I'd just like to add here Navin, that not all subs are dual 4".

For example the GTO1202D is a dual 2 ohm sub. 2+2. One problem with that is, if connected in parallel AND bridged, the effective impedance "seen" by the amp is 0.5 ohms!

But 2 ohms to each channel (as Pranil wants to do) is quite safe.
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Old 4th October 2005, 12:55   #20
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sure Sam. subs such as the one you mentioned are made just for the kind of application pranil's got.

pranil, in short 4 ohms per channel for a car amp is safe, 2 ohms and your making the amp work hard, 1 ohms and most amps dont like it at all.
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Old 4th October 2005, 20:14   #21
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Guys,

Lets take two cases :

a) DVC Sub with 4 Ohms Voice Coils : Load = Series 8 Ohms ; Parallel 2 Ohms..As I wrote earlier the problem with this configuration is the impedance. In Series it presents 8 Ohm load which results in lower power extraction from the amplifers. And 2 Ohm load will cause bridges amplifers to starin. As most amplifiers available are not stable below 4 Ohms in bridged mode. So the amps which can deal with these subs should be stable down to 2 Ohms at least.

b) DVC Sub with 2 Ohms Voice Coils : Load = Series 4 Ohms ; Parallel 1 Ohms..In series these subs with present 4 Ohm load which is perfect when used with bridged amplifiers. When paralleled, 1 Ohm load is very tough for average amplifers to handle and they will run in protection mode. To take 1 ohm load the categaory of amplifers are expensive.

As far as the powering the coils seperately is concerned, thats also not a great idea. First its a drop in the power in the amps and most important is that the output of two channels is not linear, There will be difference in output of the two channels and the subwoofer coils should get the same power else it can lead to damage of the subwoofer. There are no amplifiers available with individual L-R level controls. So bridged is the way to go.

Sam, wiring a DVC 2 Ohm sub in parallel will give a load of 1 ohm not 0.5 ohms.

Navin you are right we have lot of 1 ohms stable amplifiers Audison VRx entire lineup, Audison LRX 1.400, TRU Technology HAMMER and more.
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Old 4th October 2005, 20:30   #22
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Quote:
Originally Posted by Sam Kapasi
I'd just like to add here Navin, that not all subs are dual 4".

For example the GTO1202D is a dual 2 ohm sub. 2+2. One problem with that is, if connected in parallel AND bridged, the effective impedance "seen" by the amp is 0.5 ohms!

But 2 ohms to each channel (as Pranil wants to do) is quite safe.
a. Pranil is using (as far as I know) a 20w x 2 amp. I dont think its going to be 2ohm stable.

b. How is a 2+2 ohm a .5ohm load in either series OR parallel?

c. 2ohms to each ch of any stereo (2ch) amp isnt safe as you have to tune the gains separately to match the output EXACT!! Else you will damage the sub. And on such 2ch amps, there is only one gain pot. As you know, amp channels on these amps are almost NEVER matched by the mfr.
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Old 4th October 2005, 22:19   #23
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Geez he wants to use a 20W rms amp to drive a sub. Pranil is this true?

ok while you will get sound out of the sub you wont get good sound.

since a speaker converts electrical energy into mechanical energy lets delve into the physics of the sub and the electronics of the amp...

car subs usually have a high BL (force factor) mated to a high Mms (moving mass). this is nesscary to get lowFs. this is akin to a big caddilac car. now powering that car with a 3 cyl maruti engine will move it but it wont be nice.

to move a sub like this your amp has to be able to swing volts into an reactive load and this means that the amp should not be restricted by it ability to dump current. I am a bit doubtful about the 20W rms amp's capabilty to so this well.

now this is as simple as i can make it. if you have an applied maths background i can PM you the polynomials used to define the mechanics of a dynamic transducer (in this case you 12" sub).

gunbir, 2+2 ohms parallel = 1 ohm. but a bridged amp will see 0.5 ohms in each channel.

i forgot pranil was using a 20W amp. BTW my sub amp has individual level controls for all 4 channels. I bridge it and run 2 subs of it. and it was built in 1987 or so.
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Old 4th October 2005, 22:37   #24
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I will most probably end up using both channels bridged delivering 40 watts to the speaker and dont laught . I am using the HU's 22 watt ( may be ) to drive my front 6" components now.

See budget and a wife can make a man very bad things.


But I did not want the answer to the power delivery I am Electrical engineer myself and can figure out the Ohms and amps although thanx for the fast response. May be I wasmisunderstood. what I meant was will the sound become less in terms of quality or better for DVC when both coild are driven seprately using two seprate stereo channels left and right.. Will at gigher volumes it will lead to confilct of interests in two coils when they are not moving in same direction .


i.e. will the soundstage improve or reduce.


There is someting missing here because if it was only question of matching the impedence any manufacturere could offer the same sub in diffrent imedences instead of all this putting in series and parallel.

Last edited by pranil : 4th October 2005 at 22:38.
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Old 4th October 2005, 23:46   #25
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Quote:
Originally Posted by pranil
I will most probably end up using both channels bridged delivering 40 watts to the speaker and dont laught . I am using the HU's 22 watt ( may be ) to drive my front 6" components now.

See budget and a wife can make a man very bad things.


But I did not want the answer to the power delivery I am Electrical engineer myself and can figure out the Ohms and amps although thanx for the fast response. May be I wasmisunderstood. what I meant was will the sound become less in terms of quality or better for DVC when both coild are driven seprately using two seprate stereo channels left and right.. Will at gigher volumes it will lead to confilct of interests in two coils when they are not moving in same direction .


i.e. will the soundstage improve or reduce.


There is someting missing here because if it was only question of matching the impedence any manufacturere could offer the same sub in diffrent imedences instead of all this putting in series and parallel.
High volume or low volume, if the two voice coils are wired in phase they will move in the same direction. If they are wired out of phase, they will cancel each other out. Even if you connect each coil to two separate amps, make sure they are wired in phase. Simple.
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Old 5th October 2005, 10:09   #26
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...and that the the votage across both coils is exactly the same.

given you got a DVC sub with 2 coils of 4 ohms I would advise using the amp bridged across any one coil. you can short the terminals of the other coil it will reduce Qes and hence Qts and hence give a bit more bass extension in the same box. leaving the other coil open will do no harm either.

If the coils are 2 ohms each then put them in series. OK.

Sorry. we did not want to discount your enginering knowledge. BTW which college did you study in?
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Old 5th October 2005, 11:02   #27
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Its always advisable to use both the coils. More over in one of the car we are powring Hertz ES300D with 75 Watts and it rocks the car in the sealed box (Sensitivity Working )

Pranil i would suggest that you bridge the amp and you use 4 Ohms SVC or 2 Ohm DVC Sub (coils wired in series) with high sensitivity with the amplifier.

Last edited by Autophile : 5th October 2005 at 11:04.
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Old 5th October 2005, 11:07   #28
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I think he already dot a 4 ohm DVC sub JB. what would you suggest if this is the case.

pranil using 1 coil will reduce sensitivity by 3db.
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Old 5th October 2005, 11:16   #29
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Sorry then his amp will be struggling..8 Ohms and 1 Ohms is too much for that amplifer to handle in both extremes and 20 W per coil is not at all advisable...he has to either change the sub or the amplifier, which ever convenient for him.
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Old 5th October 2005, 11:30   #30
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...that is why i suggested 1 coil useage of the sub. might be the only rational way one can mate this amp and sub.
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