Learn the Basics before having fits about answers you don´t like.
As in Ohm´s Law.
Ha Ha, this joke belongs in Cal Weldon´s thread 😉
You managed to quote the two IRRELEVANT parameters, quite a feat.
Think gain matched within 0.1% and offset within 10mV or less and we might be talking 😉
Then please apply it.
Maybe a refresher course wouldn´t hurt.
Starting to think you have your own definition of "Physics"
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Forget it. I ask for a couple of simple questions... people go off on a tangent and they can't let go of it. I mean, people really spend time and effort on such things.
I suppose I shouldn't bring up the time invariant inductive circuit resonance at this time..
I didn't expect the Spanish Inquisition here of all places... What is this... the forums over at ASR too slow nowadays?
Let me explain why "voltage has nothing to do" here... something so fundamental that it's right there yet you don't see it.
In general
Pmax(t) = ( Vmax )( I(t) )
And for peaks, again the classic problem taking into account a perfect circuit:
Imax = Pmax / Vmax
However, the circuit too can reach its current maximum due to heat, internal component power dissipation, design characteristics, low load impedances...
Meaning at it is possibly to reach Imax when Vmax has not been achieved: When you get into peaks. where the POWER than one channel can deliver is reached, you will see that I becomes Imax... meaning... no more power. If you try to push it harder, it just won't.
In this case, it is not the power supply holding back the delivery of power, but other parts of the circuit.
Under such circumstances, if you can deliver more current, as in having a second amplifier that can deliver current, then you can hold the voltage up to to Vmax and you will be delivering more power indeed.
Do you now understand my point?
Can you refute it?
Now, don't be nasty, just tell me, is my analysis wrong... and if so. WHY? Please don't just give me Ohm's Law because that is not in discussion in this thread, it was NEVER meant to be so, the whole point of my bringing this thread up was to discuss the output impedance of a parallel topology and its ability to deliver more current, and power, on peak transients, not on a steady state, RMS, condition.
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So far, some 100 posts on that.
You certainly can´t complain [shrug]
Funny you complain about somebody "insulting" you (which he didn´t), precisely by insulting him.
Sadly you don´t understand your own contradictions.
A tiny personal doubt: that "EE" after your name, are those name initials (as in, say, Edward Eustace) or are used to hint you are an Electrical/Electronics Engineer?
Dude, I'm really DONE with you. This is enough.
You can not address the point, you will not address the point, instead you insult me.
EE is there because E was taken.
For the first time in 12 years, I'm going to ignore someone on these forums... adios.
How would English say: One picture is worth a thousand words.
If you are that sure just go buy two 0.1 Ohm resistors or whatever you have calculated, tie 2(3,4) amps to the load, power it up, crank up the volume and enjoy the result. This will prove you right (or wrong). Be grateful and share the results, video clip preferred.
If you are that sure just go buy two 0.1 Ohm resistors or whatever you have calculated, tie 2(3,4) amps to the load, power it up, crank up the volume and enjoy the result. This will prove you right (or wrong). Be grateful and share the results, video clip preferred.
Just measure the current.... into the speaker, and out of each amp when using multiples. Then you will see.
Current is the consequence of the voltage (potential) difference between two points, but only if there is a load to conduct the current.
It seems that you didn't see my previous post, where I mentioned the reasons for paralleling the output transistors; related to the ideal voltage source...
What techtool suggested above is also a completely valid approach to understanding what's going on.
I started with the theory but then spent many years playing with amplifiers, loads, tone generators and oscilloscopes.
Seems like we're talking past each other.
What happens when the load is so low and the gain (peak) is so high that it puts stress on the circuit's ability to provide enough current to maintain the voltage to the load?
In vernacular... clipping. Or... brownouts.
Now, what happens if you have two amplifiers in parallel that share the load?
My thought here is that they both will drive enough current to maintain the voltage at the output and not clip.
OK, perhaps... the question in my mind then... how does an amplifier see the load when it is in parallel with another amplifier? Assuming that both amplifiers are perfectly matched so the don't drive each other.
A truly entertaining thread! So much so that i feel obliged to contribute🙂
It is interesting to observe a relatively naive question being asked, and the deluge of straight forward, helpful, advice that resulted. And yet 100 posts later the single obvious approach being set aside as uncceptable.
I will not add further to the preceding other than to say:
The common sense answer has been sitting there on the table for most of the discussion.
dreamth posted a schematic of the output stage and I note current limiter to protect the output stage. dreamth posted advice that this can be bridged, I personally would simply leave the amp unopened and drive them in bridge. To the extent of bridging, I totally agree with dreamth's advice. The output devices are quite rugged and the protection around them good, if somewhat conservative.
The limitation on output power in bridged mode is a result of the overcurrent protection rather than the power supply from my cursory inspection of the schematic. The current limit is 3A which seems to me to be on the low side (look at the schematic posted). Slipping this up to 4A or even a touch more would not strike me as a scary thing to do. You could run the math on the SOAR of the output device if you wanted.
Current limit aside, I would immediately bridge the thing and give it a try. Comments on this:
Lets see if this common sense advice can get torched too 😉
It is interesting to observe a relatively naive question being asked, and the deluge of straight forward, helpful, advice that resulted. And yet 100 posts later the single obvious approach being set aside as uncceptable.
I will not add further to the preceding other than to say:
- Parallelling power amplifiers is not "a thing" for extremely good reason. If the manufacturers used 1% precision parts in manufacture (not a given) then you could be looking at in the region of 0.3 volt of difference between channels at peak output (for 30V peak output), that is a Amp through your external resistors.
- Consider the resistance of your crossover. This will be good parts of an Ohm. Then ask yourself about whether you need to be that fussed by the damping factors of the ampifier. A low output impedance for a power amplifier is a good thing, but it is only part of the overall system.
- Music is not a sinewave, and has a really significant crest factor. While there is supply rail droop in ant unregulated linear power supply as you find in a power amp, on music signals this is generally modest, and parallelling a power amplifier in an effort to reduce this is missig the point. If there is a 10% droop (a LOT for a music signal) and parallelling the aplifiers somehow makes this zero, this is only a 0.9dB change in output.
The common sense answer has been sitting there on the table for most of the discussion.
dreamth posted a schematic of the output stage and I note current limiter to protect the output stage. dreamth posted advice that this can be bridged, I personally would simply leave the amp unopened and drive them in bridge. To the extent of bridging, I totally agree with dreamth's advice. The output devices are quite rugged and the protection around them good, if somewhat conservative.
The limitation on output power in bridged mode is a result of the overcurrent protection rather than the power supply from my cursory inspection of the schematic. The current limit is 3A which seems to me to be on the low side (look at the schematic posted). Slipping this up to 4A or even a touch more would not strike me as a scary thing to do. You could run the math on the SOAR of the output device if you wanted.
Current limit aside, I would immediately bridge the thing and give it a try. Comments on this:
- Protestations on "damping factor" are red herrings - in this situation you are doubling the effective output impedance, which will still likely be less than your speaker wire impact, let alone crossover.
- Protestations on distortion are likely only true to the extent that the ampifier will be running at higher currents but at the same output level (power) things will be largely the same.
- There is no need to open the box to gain this increase in power.
- The amplifier includes reasonable protection, so it will take a heroic effort to brreak anything if doing something as convetional as bridging it.
Lets see if this common sense advice can get torched too 😉
Notionally yes.
With qualifications.
If you are lucky and parallelling the amplifier works, and you can get everything macthed perfectly. (totally possible if you are careful) then:
1. The Maximum voltage you can get across the speaker will be the same between one amplifier set up and two amplifiers in parallel. * and ***
2. The total current through the speaker will be the same between one amplifier set up and two amplifiers in parallel.
- One way or another this "total current" has to come from the amplifier(s). Thank you Mr Kirchoff.
3. The current delivered by each amplifier will be notionally half in the parallelled set up compared to the single amplifier set up. **
* OK, there might be a very modest increase in voltage achievable with two amplifiers - refer previous post, this will likely amount to a fraction of a dB.
** The accuract of current sharing will depend how large a matching resistor you stick in series with each output.
*** The fact you will love voltage across your matching resistors will effectively offset the gain in output voltage achieved by parallelling the amps.
OK, so you postulate that there is not much to be gained by paralleling an amplifier and the preferred approach will be to bridge... or perhaps just to get a "bigger" amp to begin with. The damping factor damage from bridging is much less of an effect than the damage of those output resistors.
That's a fair enough answer.
The question was not "naive".. just a question. There is a fair amount of documentation on paralleling an amplifier but it is not something often seen done. Why? I won't go over most answers, since they did not really answer my questions. Some did, as you.
I have already ran these amps bridged. They actually sound OK. But, let's face it, there is little challenge on wiring it up and flipping a switch. If I went that route, I'd buy Bose soundbars forever. Not my style, rather take the challenge.
I'm still curious about the equations behind how amplifiers in parallel see the load.
Thanks.
Time to dig out the A5/60s I think.
BTW, the speakers I plan to drive are a pair of Elac UniFi B5.2s that I just got two weeks ago.
Thanks for the answer.
BTW, is that a typo? Should that be "lose"?
Which, btw, is a killer point. I had reasoned that power would be lost through that resistors. Hmm.. true, so whatever power I might gain on transients... meaning that two amps can deliver a bit more current on peaks to keep the voltage from sagging... we still need to take into account the power lost in that output resistor.
So not much is gained, if at all.
TS is not that eager to perform a very simple experiment,
perhaps understanding the outcome.
perhaps understanding the outcome.
Much ado about nothing: it appears it was all about bragging.
Mouser, 1%, 100W, wirebound resistors are ~18 bucks each, part number :
Mfr. Part #
HSC1001R0F
Mouser Part #
279-HSC1001R0F
There is also another 1%, 100W, wirebound resistor, but these are ~160 bucks each
Mfr. Part #
RH1001R000FE01
Mouser Part #
71-RH1001R000FE01
Do you know why such a difference?
BTW, I go rid of my old Tektronix analog scope a long ago... I've been thinking of getting a new one... since I don't plan on doing anything RF, I figure 100 Mhz and two channels is likely enough. Any ideas? It'd be nice if it had an USB interface so I take snapshots of the screens and perhaps some programming.
My recent experience with scopes at work is completely out of scope (*) for my personal needs. At the office(s) we use very expensive scope nowadays. They are full blown computers on their own.
(*) That . is . a . bad . pun!
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Such reactions from people with incredibly low reaction scores!
Would it be possible to put a lid on it?
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This one is an overkill
The cheaper one will do. Maybe get 4 x 8 ohms, so you can play with 16/8/4 ohms (stereo, both channels driven) combinations..?
If paralleling the amps, make sure they don't oscillate. You could add a bit of capacitive load... just as a simulation of speaker wiring capacitance.
The cheaper one will do. Maybe get 4 x 8 ohms, so you can play with 16/8/4 ohms (stereo, both channels driven) combinations..?
If paralleling the amps, make sure they don't oscillate. You could add a bit of capacitive load... just as a simulation of speaker wiring capacitance.
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