quote:Originally posted by netlohcs: As far as the rules for DB drag. You are correct, there is a rule stating that that the maximum potential voltage is 18 volts DC. Notice that it specifically says DC, and mentions nothing of AC. If you put your voltmeter on DC and measure between the - terminals of the batteries during a burp, your going to get a big fat 0
That's the point I didn't pick up on. Since the higher voltage rail of amp 1 is connected to the lower voltage rail of amp 2, they are at the same potential. The lower voltage rail of amp 2 is referenced to the ground of battery 2. (I already said this stuff...) So the potential difference between the 2 batteries comes from the fact that there is a potential difference between the lower voltage rail of each amp and these are referenced to the 2 batteries. The output of the amp is AC, obviously. However, don't the rails have constant voltage on them and the circuitry in the amp swings back and forth between the high and low voltage rails to produce the AC signal? If this is the case, would the voltage measured across the rails be measurable as a DC voltage? (I'm not to sure about the specifics of how amps work or how they are laid out internally, so I don't even know if that measurement is possible.) If I understand correctly, the lower voltage rail would be at the same potential as the battery - on that amp, since it is referenced to the battery -. If this is indeed the case, then why would you not be able to read a DC potential difference between the 2 batteries?
Again, I've never had an amp apart or had any formal education on how they work, but I have a good understanding of the basics of electricity and have taken E&M. I am currently in Electrical Science. Besides that (and those courses are pretty irrelevant) I've been reading Termpro as well as other online sources for around 2 years absorbing information about a lot of car audio related topics. That includes a few months of reading easily several hours/day when I was injured. I do pretty good with absorbing/recalling information, but I'm always interested in learning more and this is a very interesting topic to me. The questions I asked weren't to say "you're wrong" because if you've done it, you've probably measured the voltage, but my questions are more to form a better understanding of why it's the way it is.
Thanks for all the information you've provided and thanks for dealing with my questions.
As far as the signal problems are concerned, I really don't know much about that subjuct (isolation) but why could you not use transformers? (or maybe there exists something in a smaller form that accomplishes the same thing?) Could you not use small transformers with the inputs wired in series with the RCA input signal and the outputs of the individual transformers wired to RCA outputs to the individual amps? I'm just guessing here, but if you had (for instance) 4 amplifiers that needed a signal, you could use 4 transformers which would each see 1/4 of the signal voltage. In this case, you could use 4:1 step up transformers to bring the voltage back up on the output side. Like I said, this is just me throwing out ideas here. It's been a while since E&M, so I hope I got the transformer stuff right, and even if I did, I'm not sure if it would be a solution to this problem or not.
posted
A transformer only physically isolates a circuit, it does not electricly; the wires do not physically touch, but they act that way.
hope this helps.
I'm semi familiar with op amps, I'd have to dig out my EE books for more info. If they wouldn't work in this situation, something else similar should. For example, op amps can be used in many ways.
quote:Originally posted by DD Cherokee: A transformer only physically isolates a circuit, it does not electricly; the wires do not physically touch, but they act that way.
hope this helps.
I'm semi familiar with op amps, I'd have to dig out my EE books for more info. If they wouldn't work in this situation, something else similar should. For example, op amps can be used in many ways.
Ok... so transformers are out. Op amps.... Like I said, I am not super familiar with all of the types that are out there. If you have the time do some research for us, and get back to us on what you find. This was not the method that I used, but I am sure there are actually LOTS of ways to do this... which is why I posted on this topic
I am very glad that we are all working together now... Isn't learning fun?
-------------------- Nate Scholten Team Sounds And Motion SS 1-2 3rd place 2004 finals -THE BUILD- ~Our Drinking Team Has A Stereo Problem~ Posts: 4253 | From: Rhinelander,WI | Registered: Dec 1999
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posted
Also, just for all of you "non-believers" out there... I will set it all up again sometime next week and take some measurements/pictures, so you can see for yourself just whats going on. Unfortunately like I said I dont have 4 identical amps in stock right now.... Would I make believers out of you if i strapped 3? I'll look around some more and see what I can dig up.
Otherwise, if anyone has some BIG amps just sitting around that they are not using, you can send them to me and i'd be more than happy to try it hee hee
-------------------- Nate Scholten Team Sounds And Motion SS 1-2 3rd place 2004 finals -THE BUILD- ~Our Drinking Team Has A Stereo Problem~ Posts: 4253 | From: Rhinelander,WI | Registered: Dec 1999
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quote:Originally posted by pipebomb: hehe,,, i know i know!!
Hey now... we will have none of that
Not yet at least
-------------------- Nate Scholten Team Sounds And Motion SS 1-2 3rd place 2004 finals -THE BUILD- ~Our Drinking Team Has A Stereo Problem~ Posts: 4253 | From: Rhinelander,WI | Registered: Dec 1999
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quote:Originally posted by DD Cherokee: A transformer only physically isolates a circuit, it does not electricly; the wires do not physically touch, but they act that way.
They act as if they touch when you feed AC through them (the signal), but not DC, right? So I thought you could produce the same AC signal through a transformer no problem while not having any trouble resulting from the constant (DC) potential difference between the input and output side. There is no path for current to flow like there would be if just using a normal RCA cable. If you're an EE, you obviously know more about this subject than me, but I'm not seeing how a tranformer would allow DC to flow from input to output or vice versa. I'd like to know about op amps though, and how they may be applicable. I've only heard of them, but not studied them.
And to netlohcs, I would love to see 3 amps strapped. It would be a more conclusive proof of concept (to me anyway) because it would show that it doesn't rely on pairs of amps in any way.
Also, you never commented on what I said about the potential between the batteries. Did you measure the potential when the amps were on? After my thinking about transformers for the signal side of things (which may be wrong), I think can see how the potential between the batteries could be zero. The power supply basically consists of a way to switch the 12V very quickly, a transformer to step up that voltage (which is essentially square-wave AC), then a way to rectify the output of that tranformer, right? Then that rectified voltage is your rail voltage, correct? If so, I'll have to think a little more on this and see if I can envision what is happening here. It's about time I break out the pencil and paper and start drawing because it's becoming difficult to see everything that's going on in my head right now.
quote:Originally posted by netlohcs: If you put your voltmeter on DC and measure between the - terminals of the batteries during a burp, your going to get a big fat 0
If this is the case, why does the signal need to be isolated? Is there an AC volage between the batteries? If so, then I can see why tranformers would not work for the signal isolation.
quote:Originally posted by netlohcs: If you put your voltmeter on DC and measure between the - terminals of the batteries during a burp, your going to get a big fat 0
If this is the case, why does the signal need to be isolated? Is there an AC volage between the batteries? If so, then I can see why tranformers would not work for the signal isolation.
There is No DC voltage present. There is AC voltages between the batteries, but it is only while the amplifiers are playing.
-------------------- Nate Scholten Team Sounds And Motion SS 1-2 3rd place 2004 finals -THE BUILD- ~Our Drinking Team Has A Stereo Problem~ Posts: 4253 | From: Rhinelander,WI | Registered: Dec 1999
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quote:Originally posted by team basket kase: What about optical isolation? Or would that have the same effect as op-amps?
Hmmmm... very interesting idea See, many heads are better than one.
What 12V companies create optical signal processing? I know Zapco did at one point (still does?) Anyone else?
-------------------- Nate Scholten Team Sounds And Motion SS 1-2 3rd place 2004 finals -THE BUILD- ~Our Drinking Team Has A Stereo Problem~ Posts: 4253 | From: Rhinelander,WI | Registered: Dec 1999
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posted
I thought of Lanzar opti-drive amps when I posted. There should be parts available for this at the electronics stores. Or of course, parting out "downed" amps, etc. I will try a search on the net, see what I can find.
posted
29 suppliers) - Optocouplers are capable of transferring an electrical signal between two circuits while isolating the circuits from each other........ still looking!
quote:Originally posted by TeamPSI: Netlochs is right...
I already have modules to do this...
Heeeeyyy now, no holding out on us.... Share the module love (or at least send me an email hee hee)
-------------------- Nate Scholten Team Sounds And Motion SS 1-2 3rd place 2004 finals -THE BUILD- ~Our Drinking Team Has A Stereo Problem~ Posts: 4253 | From: Rhinelander,WI | Registered: Dec 1999
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quote:Originally posted by TeamPSI: Cant do it man!
You may be seeing a few pretty soon though!
Awwww
I'm sure we will be seeing these pretty soon though. If this type of setup is deemed "legal", any competitor that was running quads with strapped pairs per coil can simply buy one of these isolators, split their batteries into two seperate banks, and be right back to where they were, while staying within the "4 electrical conductors per sub" rule.
Oh wait... this was supposed to be a "what if" post, wasn't it? Dang it
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posted
My theory on this, as an electrician, is that you COULD do it, butyou'd need a very precise phase variation circuit to modify the phase going in so that the signals would be complimentary. In this instance, the voltage would stay the same, since the output voltage would be identical on the amps, but the current would double (1 strapped pair compared to 2 strapped pair) which would cause the aforementioned melting of the tinsel leads (Current causes heat, not voltage) so if you strapped 4 amps, you may end up with coils that look like a puddle of melted solder in the bottom oc the gap.
It IS doable, but I'm just not sure how wise it would be.
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posted
from what I've heard the planet audio TT series amps can be strapped as many times as you want. and planet audio claims that their amps are stable to 0.3 ohms for burps
-------------------- What do you get when you argue with a moron?
quote:Originally posted by Sassmaster: My theory on this, as an electrician, is that you COULD do it, butyou'd need a very precise phase variation circuit to modify the phase going in so that the signals would be complimentary. In this instance, the voltage would stay the same, since the output voltage would be identical on the amps, but the current would double (1 strapped pair compared to 2 strapped pair) which would cause the aforementioned melting of the tinsel leads (Current causes heat, not voltage) so if you strapped 4 amps, you may end up with coils that look like a puddle of melted solder in the bottom oc the gap.
It IS doable, but I'm just not sure how wise it would be.
Phase variation circuit? ummm.... huh? You would definitely want the phase of each amp to be exactly the same... so i'm not sure exctly what you are referring to here.
We are wiring amplifiers in series, you understand that, correct? (not trying to be an ass at all, just honestly asking)
As far as the voltage/current thing.... Every time you double voltage, you also double current, assuming the load through which the voltage is applied stays constant. We know that any given amplifier can produce a maximum voltage, and also has at some point, a limit on how much current can be produced (if this wasn't true, you could just keep lowering the impedance seen by the amp more and more, and keep getting more power out of it).
Sadly, this isn't the case, which is why we need to be concious of how much current we are asking these amps to produce.
Lets say we have two amplifiers that we want to strap together, each one is designed to be bridged into a 4 ohm load, and is capable of producing 100 volts rms. This would equate roughly to 2500 watts.
(v^2)/R=Watts (100^2)/4=2500
We can then determine that this amplifier is capable of applying 25 amps through the load.
Watts/V = I 2500/100 = 25 amps
Now say we "strap" 2 of these amplifiers in series, giving us 200 volts of potential to work with. We know that our amplifiers are only capable of pushing 25 amps of current through the load. We can then determine that we need an 8 ohm load.
V/I=R 200/25=8 ohms
however, with this setup, we will be delivering 5000 watts to this load.
(v^2)/R=Watts (200^2)/8=5000 Watts
Anyways, I hope that made sense, and didn't waste too much of your time.. i'll shutup for now
-------------------- Nate Scholten Team Sounds And Motion SS 1-2 3rd place 2004 finals -THE BUILD- ~Our Drinking Team Has A Stereo Problem~ Posts: 4253 | From: Rhinelander,WI | Registered: Dec 1999
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posted
actually, every time you double the voltage, you don't double the current, you need to do a little studying of ohm's law... watts = volts times amps, if you doubled the voltage, with the same power, you'd cut the current in half, and if oyu doubled the wattage, you'd either double the voltage OR the current. if you doubled both it'd quadruple the wattage.
you really need a lesson in basic electrical theory.
P=EI Power (watts) = Energy (volts) X Intensity (current, in amps)
so from your example, 25 amps X 100 volts equals 2500 watts, which is true.
50 amps times 200 volts doesn't equal 5000 does it?
no it equals 10,000
25 amps times 200 volts or 50 amps times 100 volts.
the 2 do not rise linearly in relation to each other.
if you double your wattage so 2P you'd need to either have to double the voltage or current. not both.
Amplifiers are basically voltage regulated, variable frequency power supplies, where you can vary the frequency output by inputting a lower level switching signal. the voltage stays the same no matter what load, so if you're paralleling 2 sets of amplifiers, you will have the same voltage as if you just had one set of amplifiers. but the current would double.
if you're wiring the amps in series, you'd have the same current, but your voltage would increase, but since the voltage is regulated, there is a very finite limit to the increase.
read up a little on electrical theory.
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posted
I think you've pretty much missed the entire point of this thread sassmaster.
"if you're wiring the amps in series, you'd have the same current, but your voltage would increase, but since the voltage is regulated, there is a very finite limit to the increase."
A finite limit? No sir... the only limit to the total potential voltage is how many amplifiers you have (and wire in series).
Like I said, I don't think you understand this thread very well. Did you even read the whole thing?
-------------------- Nate Scholten Team Sounds And Motion SS 1-2 3rd place 2004 finals -THE BUILD- ~Our Drinking Team Has A Stereo Problem~ Posts: 4253 | From: Rhinelander,WI | Registered: Dec 1999
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posted
This is too easy. Look at the old booster amps. They were nothing but transformers.Wire as many amps as you wish in phase just to keep it simple. Add a 1 to 1 transformer or so to the speaker outputs. series the output of the transformers together.
you now have electrical isolated outputs which can be added together.
-------------------- My 45's want fit in that slot! Posts: 1169 | From: Rowlett, TX, USA | Registered: Jun 2000
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