Sometimes you read a thread just for fun and to learn a thing or two but this thread isn’t fun. There is unbalance and not enough respect. A pity really, I read all posts and many knowledgable members have provided valuable and helpful input and get a too harsh reply in return.
Sometimes others know their stuff and you have to accept that. I am the last person on this forum that should start about the tone but it would be a good thing to count to ten if you are helped by people in their spare time for free and you don’t get the expected replies.
Sometimes others know their stuff and you have to accept that. I am the last person on this forum that should start about the tone but it would be a good thing to count to ten if you are helped by people in their spare time for free and you don’t get the expected replies.
I was very frustrated from the very get go because some people were stuck on things that were not part of my question and when I tried to steer them back to a discussion of the behavior of a parallel topology they started to get nasty. It's not a question about knowledge, it's a question of "scope".
Like being in a peer review at work... you got to keep things in scope.
OTOH, some people have been very helpful and observant, thanks for that.
I'm looking into setting up a parallel configuration. I don't need to be told that I should do bridged or anything else.. and for sure I don't need to be told that I'm lying or have any other ulterior motives.
I was clear at the onset: output impedance based on damping factor specification, load impedance, gain, current drive and a way to calculate the proper values for the in-series resistors.
By the time I posted, I had read quite a bit on the literature available on the Internet. I know enough about electronics that I don't need to be told I am a troll/student/ignoramus/bragging and I am looking into transient behavior, not steady state.
What I have learned so far:
(1) It's better to increase the capacitance of the power supply to handle transients.
(2) The power loss the in line resistors will negate much of the gain of having additional current drive available.
(3) Damping factor will be affected by the in line resistors.
So, perhaps, running a parallel set up just doesn't make much sense and is the reason why we don't see it very often.
Given the facts, then my options are simple:
(1) Put two Z-amps in the Z-rack and run them bridged.
(2) Use a mini-monitor so the effects with damping at 20Hz won't make any difference.
(3) Use a different, more powerful amplifier from the collection, but this won't fit into the Z-Rack.
(4) Get some power resistors, some wires, plugs, a reasonably priced scope and have some fun and risk one of the Z-amps.
I think I will do (1), (2) and (4) above.
Why?
How else can I match them?
I suppose the more High End the amp is, the better matched the components and channel behavior would be. But having two channels share a circuit board would minimize many of the possible differences. At the very least the channels would have very closely matched gain characteristics, huh?
(1) I think something is lost in the meaning... I know loads draw current, my wording is likely being misconstrued here. The idea is to provide current available to keep the voltage from sagging at high power transients.
(2) Yes, upping the capacitance in the power supply works, but as I posted in the beginning, I have the amps and I want to use them as a "black box". Not opening them. I'm pretty sure I have pointed this limitation out already -for my application.
(3) In general, when you have the ability to change the amplifier, you are quite correct. Heck, if you think about it... if you're gonna change the amp what would be easier to do?
(3a) increase the power supply capacitance (and the transformer)
(3b) increase the power supply voltage.
Now, (3b) transcends the use of a parallel configuration for sure and might smoke some components for sure, while (3a) might be easier. Actually, won't (3a) also put components in danger? Maybe they'll will overheat by putting out too much power?
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Another thing you might do with multiple amplifiers, and this may already have been mentioned upthread, is to bi-amplify, or possibly tri-amplify your speakers. This wouldn’t have to be done with an active crossover, although that’s generally the best way. It might also be doable via your speakers existing passive crossover. In which case you would have to seperate/isolate each driver’s relevant crossover network. Be warned, that your speakers crossover design may not easily lend itself to such a separation. It’s not uncommon to find that the tweeter’s network is cascaded off of the midrange’s network, and so is not a simple separation. For that reason, I suspect it‘s more likely that you will be able to cleanly separate the woofer’s network from that of the tweeter and midrange, than to separate all three.
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Yes, but the speakers I want to do this with don't allow bi-wiring/bi-amping at all. Otherwise, that would have been my first crack at it. I was indeed thinking of switching speakers with my wife's office, her english mini monitors allow bi-wiring and they sound awesome under such conditions (*) but she likes the way they sound.
I used to run the big PSBs in our den's HT biwired/biamped and they sounded awesome. Those speakers have truly separated paths.
Now, going off a tangent, it's interesting that some speaker designers don't allow for even bi-wiring at all.
(*) I used to run them in my main system with two stereo amps... you can imagine the cabling! ;-)
In which case, as Marcel said early in the thread, your only option looks like bridging of amplifier pairs. Which requires applying a differential input signal across the pairs. If successful, power delivery to the load could potentially increase by a factor of four, but there are some potential issues in implementation which you may not be up to addressing on your own.
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Please don't quote the entire post just above yours. This thread is bad enough, we don't need to read things twice.Endless arguments from people who don't know forum rules, procedure, form and etiquette put the thread at high risk of closure.
Just reread the thread. It's been explained to you several times, including me.
Reread the tutorial. Look at the recommended parts! That's your answer.
"having two channels share a circuit board would minimize many of the possible differences." Not so much. Look at my posts again!
"At the very least the channels would have very closely matched gain characteristics" Not necessarily. Reread the excellent advice you've been given.
Sorry, but I've read the entire thread and I don't see that advice.
Why wouldn't a pair of channels sharing the same chassis, same power supply and same circuit board have different gain characteristics and different output impedance?
Honestly, point out the place where this was explained...
Resistor tolerances, transistor variations. They are analog and will not match exactly.
G²
G²
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A stereo amplifier (especially a vintage unit) would not be built with closely matched (0.1%) high stability resistors. Amplifiers designed for paralleling would most definitely have this feature.
Look at the TI applications sheet, and look at the resistors specified for the feedback loop. I guarantee you these units were not built with 0.1% resistors.
OK, fair enough. So it comes down to the quality (and cost) of the BOM?
If I took a DIY Aleph 5/60 it might work (on account of quality been important here)... or maybe an OEM Krell... but I'd be nuts to do that. Is that why the application notes call for such -relatively- large resistance on the output resistors? To allow for the differences in channel operation? I mean, putting a 1ohm down from a 0.02 output resistance seems excessive otherwise.
Now, let me really be nuts.... how about driving something like a pair of low powered F5s? Most of the time it would be loafing but during those peak times when it needed drive, it would be able to deliver current. That's why I brought up this thread to begin with.
I know, I know, the F5 Turbo V3 would make more sense (something I'm sort of dreaming of), but...
So, I guess I'm back to square one... but now I understand the limitations and the why.
Thanks.
PS- I still want to get the scope and the resistors... why not?
Not really and I expected better insight from you.
What they say is, actually:
Which we have all been saying from day one.
That does NOT mean current will actually increase by paralelling amplifiers (what TonyEE wrongly says and confirms multiple times) since he does not change load impedance.
Period.
Plain wrong.
They conveniently "forget" to consider balancing resistors will actually INCREASE output impedance.
Notice they MUST NOT be included in the feedback loop.
Which is absolutely NOT the case here, not sure why would anybody use this example in this thread.
Again (for the Nth time 🙄 ), tonyEE said current will double in the same speaker, quadrupling the power.
He even "showed the equations" 🙄
Sure thing.
They also increase source impedance and waste power, but who´s counting?
And of course do not double, even less quadruple power.
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You caught him LYING red handed 😉
Why am I not surprised?
Lying through the teeth, trolling and stubbornly arguing against Truth sometimes ends up triggering that.
That said, nobody was rude here.
Peer review...what a fancy expression to use on DIY audio!
That's how you get those PHD titles this days..you get reviewed on DIY audio, you start quoting your reviewers putting it down on paper with the help of a printer...and that's it! You get your " teacher of logics title" :
That's how you get those PHD titles this days..you get reviewed on DIY audio, you start quoting your reviewers putting it down on paper with the help of a printer...and that's it! You get your " teacher of logics title" :
Why do you have to ridicule so much? I don't poke fun at you. You sure seem to like spending lots of your time ridiculing stuff.
"Peer reviews" are common in what I do. As a matter of fact, I did a peer review for someone last week and I had one done for my stuff. We are in the middle of an integration effort.
Peer reviewing is not a joke, it's a way for teams to work together and it builds some thick skin and the ability to give and take, strictly in a professional way, not ever insulting the other person's ability or motives. It's an awesome, very efficient way to find the best solution.
In any event, my questions have been answered by others who provided constructive criticism.
"Peer reviews" are common in what I do. As a matter of fact, I did a peer review for someone last week and I had one done for my stuff. We are in the middle of an integration effort.
Peer reviewing is not a joke, it's a way for teams to work together and it builds some thick skin and the ability to give and take, strictly in a professional way, not ever insulting the other person's ability or motives. It's an awesome, very efficient way to find the best solution.
In any event, my questions have been answered by others who provided constructive criticism.
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