I would like to bridge a 4 ohm stable amplifier into 4 ohms.. that means 2 ohms per channel.... Are the only limiting factors the transformer and the power disipation of the output devices? I was planning on doing a 6 channel amplifier with 1 HUGE heatsink... Which means all the devices will be mounted on the one heatsink.... so, if I was to bridge 2 channels, the other 4 will be unused, and therefore generate no heat... also, the transformer will have all available power... 🙂 So..... could I put extra transistors on 2 of the output channels so just those 2 channels will be used when bridging into 4 ohms?? Basicaly, i want an amp, that will give ~800watts RMS into 4ohms.. why?? Well, to totally trash all these peoples "1000watts RMS" subs.. 🙂 lol
Could a subwoofer (15inch) really handle 1000watts RMS CONTINUOUS (sine wave) WITHOUT ripping itself apart? I know at some frequencies it will... but at the lower frequencies... ITS GOING TO BURN!!! lol
"two ohm stable"
"2 ohm stable"
two ohm stable
2 ohm stable
^^^^^^^^
They are there so people can find this info if they search... I could't find ANYTHING!! lol
Could a subwoofer (15inch) really handle 1000watts RMS CONTINUOUS (sine wave) WITHOUT ripping itself apart? I know at some frequencies it will... but at the lower frequencies... ITS GOING TO BURN!!! lol
"two ohm stable"
"2 ohm stable"
two ohm stable
2 ohm stable
^^^^^^^^
They are there so people can find this info if they search... I could't find ANYTHING!! lol
It is difficult to answer in general. Just take to the account that every branch of your bridged amplifier will have to deliver 2 x higher peak current into the load (compared to single, non-bridged amp).
I will answere at your second part question.
Yes , a single 15" speaker can do easy this job only if you can't run on clipping and if you will use a high-pass filter ( 18 or 24dB/oct) at 20 or 25 Hz.
But if you wanna be the best , use more speaker at less power.
Four 10" /8ohm speakers at 2 x 500w/4ohm will give a better response .
Yes , a single 15" speaker can do easy this job only if you can't run on clipping and if you will use a high-pass filter ( 18 or 24dB/oct) at 20 or 25 Hz.
But if you wanna be the best , use more speaker at less power.
Four 10" /8ohm speakers at 2 x 500w/4ohm will give a better response .
PMA said:
I'm sorry, I don't really understand what you are saying... I would liek to be able to bridge 2 out of the 6 channels into 4 ohms... the other 4 will only be used bridged into 8 ohms minimum, or not bridged at all... 🙂 so, double the output devices to increase the thermal transfer, or whatever.. lol anyway, yeah... 🙂 thanx for teh help so far.. 😀
SkinnyBoy said:
You probably know this, and maybe the way you put it is just that.
But you do not "bridge" into a certain impedance like when you parallel speakers.
In fact, if you could say that you "bridge" then you do it into the larger impedance really. Your bridged amp will not be as tolerant of lower impedances (i.e.: 4 ohms) as the unbridged amps, quite the opposite.
You may have to do a bit more than doubling the devices, like lowering the supply voltage, correcting any internal protections or increasing the heatsink area.
Carlos
carlmart said:
Ahh... not I am even more confused.. forget it, I'll just only bridge into an 8 ohms speaker.. 🙄 lol
What's the application?
In general, bridged amps have a number of disadvantages some of which get worse into low impedance loads. Consider:
A bridged amp has twice the Vce drop as a non-bridged amp which means it's going to run a lot hotter.
Bridged amps have double the output impedance which means half the damping factor. This is especially an issue for a low impedance subwoofer.
Roughly speaking a bridged amp has twice the distortion of the same amp not bridged. Most forms of distortion usually rise as the impedance drops. It's not uncommon for THD to roughly double at high power levels as you cut the imedance in half. A bridged amp multiplies that by two again.
Bridged amps often don't clip as cleanly as non-bridged amps.
So, if you don't mind two power supplies, it would make more sense to design a non-bridged 4 ohm amp to deliver however much power you need for the subwoofer(s) and then power the other channels from perhaps different rail voltages if necessary.
In the car stereo world, a lot of guys have found they get significantly better bass by NOT bridging the subwoofer amp(s). Even though most of these amps are rated to run bridged into 4 ohms they're not very happy doing it.
In general, bridged amps have a number of disadvantages some of which get worse into low impedance loads. Consider:
A bridged amp has twice the Vce drop as a non-bridged amp which means it's going to run a lot hotter.
Bridged amps have double the output impedance which means half the damping factor. This is especially an issue for a low impedance subwoofer.
Roughly speaking a bridged amp has twice the distortion of the same amp not bridged. Most forms of distortion usually rise as the impedance drops. It's not uncommon for THD to roughly double at high power levels as you cut the imedance in half. A bridged amp multiplies that by two again.
Bridged amps often don't clip as cleanly as non-bridged amps.
So, if you don't mind two power supplies, it would make more sense to design a non-bridged 4 ohm amp to deliver however much power you need for the subwoofer(s) and then power the other channels from perhaps different rail voltages if necessary.
In the car stereo world, a lot of guys have found they get significantly better bass by NOT bridging the subwoofer amp(s). Even though most of these amps are rated to run bridged into 4 ohms they're not very happy doing it.
Yeah, its kewl.... I really just wanted an amp that would do 800watts continuous into 4 ohms using only +-50volts... but its ok.. 🙂
I see no particular reason not to bridge two amps. Make sure each channel is very stable into a 2-ohm load and that you get your grounding right - this is important. Otherwise, just check that each channel will work on its own into a 2-ohm load: current, power dissipation, protection, power supply. I'd recommend using a single psu for both channels so as to avoid grounding complications.
I'm not sure I agree about the distortion issues that nv_avphile talks about. I think a bridged amp may well be less distorted.
traderbam said:
Now now.. we don't want to start an arguement.. 🙄 As for power disipation, all 6 channles will be mounted on 2 heatsinks, which means when I bridge 2 channles, they will be on opposite sinks, and only the bridged channles will be running, so the whole heatsink will be used for cooling.. lol wow,I ama bad typer.. 🙄
So much power...
SkinnyBoy,
It's very difficult for an amp to drive 2 ohm loads.
It has to be a good one.
If you bridge it, it's going to be worst.
For example, if a non-bridge amp is stable at 2 ohm loads (a good one), if you bridge it, you can only drive 4 ohm loads.
That's the general rule.
So, before you do something to your amp, if you have the money, buy a Krell (they are normally stable to 1 ohm loads).
I know, it's expensive...
Why do you need so much power inside your home?
Are you going to give a live concert?
Don't be so excited with power, because in Audio, power is not linear, and that's why volume pots have to be logarythmic (if they are linear, they have some trick to make the log).
So, 100 watts RMS in fact is 2 times (yes, double) the power of 10 watts RMS.
Seriously!
For me, the important is the capability to drive speakers (the current).
I would prefer a good 50 watts RMS amp that doubles the power figure until 2 ohm loads than other of the "usual" type that has 100 watts RMS / 8 ohms and 140 watts RMS / 4 ohms.
SkinnyBoy,
It's very difficult for an amp to drive 2 ohm loads.
It has to be a good one.
If you bridge it, it's going to be worst.
For example, if a non-bridge amp is stable at 2 ohm loads (a good one), if you bridge it, you can only drive 4 ohm loads.
That's the general rule.
So, before you do something to your amp, if you have the money, buy a Krell (they are normally stable to 1 ohm loads).
I know, it's expensive...
Why do you need so much power inside your home?
Are you going to give a live concert?
Don't be so excited with power, because in Audio, power is not linear, and that's why volume pots have to be logarythmic (if they are linear, they have some trick to make the log).
So, 100 watts RMS in fact is 2 times (yes, double) the power of 10 watts RMS.
Seriously!
For me, the important is the capability to drive speakers (the current).
I would prefer a good 50 watts RMS amp that doubles the power figure until 2 ohm loads than other of the "usual" type that has 100 watts RMS / 8 ohms and 140 watts RMS / 4 ohms.
yeah, I know..... I just wanted to be able to get some STUPID amount of power into a 4ohm car subwoofer.. thats all.. 🙄 lol thanx for all the help everyone.. 🙂
- Status
- Not open for further replies.