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charlesB Unregistered guest | I'm sorry to waste your time, but what exactly does bridgeable mean? I'm very new to this. Thank you |
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Bronze Member Username: Sublime420Ca Us Post Number: 23 Registered: Jan-05 | its means that u could take a two channel amp that does like 400 watts on each channel and wire it so it does 800 watts to 1 channel. |
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charlesB Unregistered guest | Is that difficult to do? and if not... would this amp be suitable for two 15" subs? http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=18797%26item%3D5740827021 %26%26 1 x 1200 Watts Max at 4 Ohms Bridged the subs are 800 max each i believe |
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Gold Member Username: GlasswolfNorthWest, Michigan USA Post Number: 7145 Registered: Dec-03 | "What is "Bridging"? Bridging an amplifier refers to configuring a two channel (stereo) amplifier to drive a single load with more power than the sum of the two original channels combined. For an example, a 100 watt per channel at 4 ohms amp may put out 400 watts(one channel at 4 ohms) after bridging. There are important things to know about running an amplifier in the bridged mode: An amplifier running in bridged mode has one output channel to which a load (speaker) can be connected. It is no longer a two channel (stereo) amp as far as input signals and loads are concerned. If the amp you want to run in bridged mode does not have built in facilities for doing so, you should not attempt to use it in this manner (unless you are thoroughly sure of what you are doing). If you run bridged amplifiers, you must pay close attention to speaker phasing (see next item). Otherwise, you may have "hollow" or "weak" sound. You must pay close attention to speaker wiring. The manufacturer will state which terminal is really the "positive" connection when bridged. The speaker output signals of a bridged amplifier are floating; such connections must never be connected to any grounded device (such as an external accessory power meter, for example). If you do make such an illegal connection, one amplifier channel is basically short circuited (worst case result is a blown amplifier!). Amplifiers running in bridged mode are generally limited to speakers with impedance ratings of no less than 4 ohms (in other words don't use a 2 ohm speaker load unless the manufacturer specifically allows it). Bridged amplifiers work basically as follows: A single input signal is applied to the amplifier. Internal to the amp, the input signal is split into two signals. One is identical to the original, and the second is also identical except it is inverted (sometimes called phase-flipped). The original signal is sent to one channel of the amp, and the inverted signal is applied to the second channel. Amplification of these two signals occurs just like for any other signal. The output results in two channels which are identical except one channel is the inverse of the other. The speaker is connected between the two amplifier speaker output terminals. In other words, one channel "pulls" one way while the second channel "pulls" in the opposite direction. This allows considerably more power to be delivered to a single load. If we had our perfect amplifier, upon bridging it we would have a single channel amplifier with exactly four times as much power as any one channel of the amplifier in "normal" stereo mode, assuming a 4 ohm speaker load. This is because the effective output voltage available to drive the speaker has doubled as a result of bridging. A doubling of voltage on a given load results in a fourfold increase of power delivered to that load. If we used a 4 ohm load on the perfect bridged amplifier, the output power would be a very substantial eight times the normal stereo single channel 4 ohm output! These numbers should give some clues as to why real world amplifiers cannot meet such expectations. Once again, we are back to limitations of the power supply. In reality, most amplifiers in bridged mode will put out about 3 times the power as any one channel of the amp in normal stereo mode. The fourfold increase cannot be achieved because the power supply is unable to provide the current required for such performance. With 2 ohm loads, the situation is compounded. The amount of current required to drive a 2 ohm load when in bridged mode will tax the amplifier's power supply to its absolute limits. Not to mention, the output stage may not be able to safely handle the extra heat that will be dissipated. Bottom line: stay away from 2 ohm loads if you are running an amplifier in bridged mode!" from: http://www.wickedcases.com/caraudio/amplifiers.html note, bridging an amp with two subs is pointless since you can put one sub on each of two channels and get the same total power. The exception is if these are two 4 ohm single coil subs, and you have a bridgeable 4 channel amplifier. then you put one sub on each of two bridged channels for full power. |
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charlesB Unregistered guest | But the two subs are 8 ohms each. So I would wire them in parellel to a bridged 4 ohm channel, right? Or can I just wire each to a 4 ohm channel not bridged? |
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Gold Member Username: GlasswolfNorthWest, Michigan USA Post Number: 7149 Registered: Dec-03 | ah ok, two 8 ohm subs.. that's another exception. yes bridge a stereo amp and wire the subs in parallel. that'll give the subs all the amp's power. |
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charlesB Unregistered guest | Ok think i got it! Lastly, would this Lanzer amp be a good choice for what i need (subs are 800 max each)? http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=18797%26item%3D5740827021 %26%26 |
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Bronze Member Username: Sublime420Ca Us Post Number: 24 Registered: Jan-05 | get something else. lanzars no good. |
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Gold Member Username: GlasswolfNorthWest, Michigan USA Post Number: 7152 Registered: Dec-03 | use the RMS rating for both the subs and amp power. ignore max or peak ratings. |
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charlesB Unregistered guest | Ok I have found this JBL GTO1201.1 http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=18797%26item%3D5741967721 %26%26 puts out 787 watts x 1 at 4ohm Does this look like a good buy? It's a little expensive but I'm willing to pay it if it's good quality. If not, any suggestions to a similar (maybe cheaper) amp? |
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Bronze Member Username: Sublime420Ca Us Post Number: 27 Registered: Jan-05 | thats a better amp. |
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Gold Member Username: GlasswolfNorthWest, Michigan USA Post Number: 7168 Registered: Dec-03 | the JBL GTO series amplifiers are very nice amps. |