hey guys, this might be a stupid question, but at least it will clear up some confusion for me.
I have a stereo amp and inverted one channel so it can be bridged. it works well with a 8ohm speaker, but gets really hot with a 4 ohm driver (not much distortion though)
is there any way to "parallel" both channels to one speaker so that both channels share the current.
basically one channel is loud enough, but i only want to run one subwoofer off it and i don't want to waste the other channel (and i want to try preserve the transisters a bit)
I have a stereo amp and inverted one channel so it can be bridged. it works well with a 8ohm speaker, but gets really hot with a 4 ohm driver (not much distortion though)
is there any way to "parallel" both channels to one speaker so that both channels share the current.
basically one channel is loud enough, but i only want to run one subwoofer off it and i don't want to waste the other channel (and i want to try preserve the transisters a bit)
well i already have the speaker so im not going to buy anouther one. i was thinking that if i have the same signal on both inputs (mono) and link the 2 positive outputs ('cause there should be no voltage drop between the two) and have 1 speaker terminal connected to the link and the other terminal to ground output.
could this actually work?
could this actually work?
In theory, yes.
In practice, no.
The AC gains and DC off-set would have to match perfectly, and even then I would want to sum the output currents through a pair of 0R5 resistors.
In practice, no.
The AC gains and DC off-set would have to match perfectly, and even then I would want to sum the output currents through a pair of 0R5 resistors.
Forget your paralleling proposal.
The single amplifier running off the stereo power supply will perform better than having two amplifiers running from a common PSU.
Most cheaper commercial gear is strangled by undersized power supplies. The reason being that a good PSU is more expensive than a good amplifier, so the good PSU goes out the window to save money and weight and volume and case size and distribution costs etc.
The single amplifier running off the stereo power supply will perform better than having two amplifiers running from a common PSU.
Most cheaper commercial gear is strangled by undersized power supplies. The reason being that a good PSU is more expensive than a good amplifier, so the good PSU goes out the window to save money and weight and volume and case size and distribution costs etc.
Hi Dan, nice to see the sun again, what bass driver are you useing? Maybe the members can recommend something that can drive it more appropriately.
well i want to run a car sub with it, i already have the driver so i don't want to get another.
the reason why i wanted to parallel the amp is because it is a cheap amp - its pretty loud but the output transisters are a bit on the weak side.
i got this idea from a friend who wants to build a chip amp - and he was talking about running the chips in parallel to increase the current.
the reason why i wanted to parallel the amp is because it is a cheap amp - its pretty loud but the output transisters are a bit on the weak side.
i got this idea from a friend who wants to build a chip amp - and he was talking about running the chips in parallel to increase the current.
this is where i got the idea for paralleling the amps. this is from a chip amp data sheet and it shows 2 chips connected to each other.
although i can understand the statement of one amp running better off a stereo PSU, in the case of my amp im not too sure, it has a really nice big toroidal transformer in it, and crappy little output transistors.
so how come you can parallel chip amps but not solid state amps??? (just curious)
although i can understand the statement of one amp running better off a stereo PSU, in the case of my amp im not too sure, it has a really nice big toroidal transformer in it, and crappy little output transistors.
so how come you can parallel chip amps but not solid state amps??? (just curious)
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"The AC gains and DC off-set would have to match perfectly, and even then I would want to sum the output currents through a pair of 0R5 resistors."
As others have mentioned, paralleling entire amplifiers can have unpredictable results. But you only really need to parallel the output transistors (and maybe the drivers). Disconnect the rest of the other channel and just parallel the "extra" output transistors. Leave in the emitter resistors and base stoppers (if any). All four outputs must be on a common heat sink or this won't work. If they're not, pull them from the disabled channel and add them to the heat sink of the one you're using.
The reason you can parallel chip amps is because the gains and DC offsets are matched, and the protection circuits have almost no lag time if something does go haywire.
The reason you can parallel chip amps is because the gains and DC offsets are matched, and the protection circuits have almost no lag time if something does go haywire.
i see that thats what they do on the chip amps. thanks for clearing up some of the confusion guys🙂
so now i have a new question, if i just upgrade the output transisters on my amp will i get a higher power output??? or is it a case of making a pc board with thicker tracks for the current?? or does the whole amp need to be redesigned??
so now i have a new question, if i just upgrade the output transisters on my amp will i get a higher power output??? or is it a case of making a pc board with thicker tracks for the current?? or does the whole amp need to be redesigned??
I used to buy a really inexpensive model of 2x75W/4R amp from Pyramid for less than $60. I would replace the 8A outputs with 25A ones, and the 25A FETs in the supply with 50A ones. It didn't put out any more power at 4R, but it wouldn't blow up now, and you could run 2R with it.
If you expect more than this the whole thing will need to be re-designed.
If you expect more than this the whole thing will need to be re-designed.
upgrading the outputs does nothing to change the supply rail voltage and this determines the the maximum output voltage and more importantly the maximum output current.Dan2 said:
If you keep the PSU as is and design the rest to optimise the voltage losses from PSU to speaker you can gain a small amount of extra power. But it is usually only measurable. You won't hear it as louder.
More power needs a complete redesign using new components throughout the amplifier.
well i have already inverted one channel of this amp so i could bridge it, it works great with a 8 ohm speaker but i want to use a 4 ohm speaker. i tried it already and lets just say i almost burnt my finger on the heatsink.....oops!
so if i get output transistors with a higher current rating then the amp should be able to handle the 2ohm load (cos its bridged) right??
so if i get output transistors with a higher current rating then the amp should be able to handle the 2ohm load (cos its bridged) right??
No.
You need about double the SOA to be able to drive the lower impedance load. Increasing the cold Ic rating and having no regard to Vce @ typical output currents achieves little if anything.
Then you need double the current from somewhere to satisfy that lower impedance load.
You need about double the SOA to be able to drive the lower impedance load. Increasing the cold Ic rating and having no regard to Vce @ typical output currents achieves little if anything.
Then you need double the current from somewhere to satisfy that lower impedance load.
No, not necessarily.
Well, what does that tell you now? You tried a 4 ohm load and the heatsink temp is excessive. Now you want to make the condition even worse with a two ohm load?
Run, don't walk to the nearest dumster and throw it away. Save your money and purchase something capable of driving your load requirement without going into melt down. What you have will not
can not nor will it ever survive the punishment you want to give it.
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