How comes my amp...

[ryan]

sorry to post another q about my amp, but ive finally managed to get it sorted out, BUT
i was wondering why my old amp that was a 2 channel 800W MAX gave my subs more volume than my new amp that is 1600w max and 900w RMS?
heres the new amp and i have 2 of the following subs:

http://www.gear.ie/Products/ItemSpecs.aspx?ItemId=147

http://www.sony.co.uk/view/ShowProduct.action?product=XM-D1000P5&site=odw_en_GB&pageType=TechnicalSpecs&category=ICA+Amplifiers


thanks guys

 

[ryan]

i was just looking at the spec of them both,
and the sub is 4 OHM and the amp only powers 500W at 4 ohms,
but im sure tom said there was a specific way to wire my subs so that they would work as 2 ohm?
i think it was along the lines of-
negative from amp to both speaker negatives and positive from amp to both speaker positives?
am i correct?

 

[ben]

if im correct,

you need to run the amp bridged. in order for this to work it needs to be a stereo aplifier rather than a MONO block amp. (it needs to have a left and a right channel, rather than positive/ negative)

if it is a stereo amp, it will have two sets of terminals per channel, these will be marked + and - left channel and + and - for the right

left right
+ - + -


to bridge the amp, which will half the resistance from 4 ohm down to 2 ohm and there fore effectively double the power (because the resistance is halfed) you will need to;

connect the positive terminal from the left channel to the left terminal on you sub,
and the negative terminal from the right channel will need to be connected to the negative terminal on your sub

this is how both of mine are set up in my 1.4 so i know it works, but dont blame me if it doesnt

 

[Tom]

Either its still wired wrongly or you've just not set the amp up correctly.

A 4ohm speaker is still 4 ohms even if the amp is bridged.

 

[Anonymous]

i know that the speaker still gives a resistance of 4ohms,

i was saying that the resistance in the circuit through the amp will be reduced from 4ohm to 2ohm,
this is half the resistance,
which means that the power to the speaker(s) is doubled.

this should increase the volume,
provided the speakers can handle the extra power that is

 

[Tom]

The impedance seen by the amp stays the same.

Bridging essentially doubles the voltage output of the amp. More volts = more power. Simple.

 

[Anonymous]

were those links there before? or am i blind?

that amp cannot be bridged, it is a mono amplifier designed specifically for sub woofers.

what head unit do you use? do you know what the power output is?

 

[Anonymous]

i think thats kinda what i meant, i think

 

[Anonymous]

just a thought, if you are running two subs@ 4ohm, does that mean that the impedance doubles to 8ohm? which would ean that the power was effectivly halfed? i thought i knew about this kinda stuff but im really confused now

 

[Tom]

You can run them in series which gives a nominal 8ohms or parallel which gives a nominal 2ohms.

And if you run them out of phase they will sound dire.

 

[Anonymous]

ahhh, that rings a bell.

with regard to the phase,

if you mount the subs in the same box facing each other and then deliberately run them out of phase, it will sound fine, it just means that the same SPL level will be acheived and you can use a box half the size which is good if space is limited

 

[Tom]

Isobaric loading.

 

[ryan]

so how do i run them in parallel to achieve the 900w RMS i am after ?

 

[Anonymous]

bump

 

[Anonymous]

sorry

 

[Tom]

Well tell us how its wired.

 

[ryan]

at the moment, speaker one is wired to the positive and negative on the amp terminal one (speaker output)
speaker 2 is also wired in the same manner
so im presuming this is the original way?

 

[Tom]

So why didn't it work when you wired it like that before?

 

[ryan]

because the amp i had before never worked in the first place, cos some dick head off ebay sold me it broken, so i ordered a refurbished one thats exactly the same and it works
discussin with paypal now for a refund