Gain setting with DMM

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thedeal7235
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Post by thedeal7235 »

i say put it up to to the 200 in that setting, cuz, ur one amp 150 by2 @4ohms, needs to measure at 24.5v ac, and the other @ 2ohm stereo? like stipud typed out, will be measured at 34.6v ac-
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neverman
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Post by neverman »

Being that I'm already hooked up and running I should be able to measure this actively correct? Meaning I don't need to disconnect my speakers at all as the dmm's impedance shouldn't effect the output dramatically?

What voltage out am I looking for?

ZPA0.5 driving eton DA hex components. I seem to remember this being a 6 ohm nominal set?

ZPA0.5 bridged driving a pair os SS-10's wired in parallel 2 ohm I think, maybe 1 ohm with dual voice coils? I forget... been a long ass time since they were installed.
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stipud
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Post by stipud »

Yes, you can do it with your speakers hooked up. I don't recommend it however, since -0dB test tones are very hard on them, by running them full out. They could easily overheat the voicecoil and be damaged. I have seen many tweeters blow from test tones.

Now this brings up an interesting issue regarding the ZPA's multi impedance operation. With no speaker hooked up, it is probably running in 4 ohm mode (there should be an LED that turns on if it's in 1 ohm mode). As such, you would have to set the gains assuming 4 ohms. Then when the amp flips to 1 ohm operation, the power supply lowers the voltage and increases current to compensate. Your gains should in theory be in the same place either way. The Xenon, which switches from 1-4 ohms falls under this as well.

So your gains set would be...
sqrt(1000 watts * 4 ohms) = 63.24v in 4 ohm operation

And when it switched modes...
sqrt(1000 watts * 1 ohm) = 31.6v in 1 ohm operation

With your component set up front, you can set the gains assuming 4 ohms. Either way the equation has to balance out.

For example, we know that when we halve impedance, we halve power:
sqrt(250 watts * 4 ohms) = 31.62
sqrt(125 watts * 8 ohms) = 31.62

Either way, the gain is set to the same voltage. Similarly we can work backwards to find the 6 ohm wattage:
31.62 = sqrt ( X watts * 6 ohms)
31.62^2 = X watts * 6 ohms
31.62^2
--------- = 166.6 watts
6 ohms

And of course:
sqrt (166.6 watts * 6 ohms) = 31.62
packersfan
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Post by packersfan »

I need some help please as my amp keeps clipping and shutting off. I have a PHOENIX GOLD 6.5" 240w COMPONENT SPEAKERS and RSD65CS Phoenix Gold RSD250.2 200-Watt 2-Channel amp running to my stock hu from a 09 ford escape and am using a inline level adaptor and it has 2 dials on it which raise the volume? How do i set the gain on the amp and the inline adapter properly that the amp does go into fault all the time or having the speaker levels high at low volume? :?: :?:
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Post by Bfowler »

most loc's recommend that the pots be set at max....did it come with instructions?
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Post by packersfan »

no instructions, max would make the levels real high?
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Post by packersfan »

any one?
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Post by fuzzysnuggleduck »

You should probably use a DMM as guided in this thread and measure the output from your LOC and set it to around 8VRMS.
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packersfan
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Post by packersfan »

As of right now the loc is only at 1/4 and the gain on the amp is set at halv aprox 4 volts i believe.If i turn it clockwise torwards 8 volts speakers shut off and think the protective circuit kicks in. so what do i do, turn the inline level adapter to 1/2 or 3/4 then measure the speaker terminals on the amp, and whatever voltage that is set the gain to it?
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Post by fuzzysnuggleduck »

You should measure the voltage on the LOC outputs and see where you're at.
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packersfan
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Post by packersfan »

i can olnly reach the pots on the adapter, where would i read the voltage on that?
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Post by fuzzysnuggleduck »

packersfan wrote:i can olnly reach the pots on the adapter, where would i read the voltage on that?
You seem to have it figured out already in the other thread, but I meant measure the A/C voltage on the RCA cables coming off the LOC (adapter). Same method you use to measure speaker terminals.
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Post by packersfan »

then what after that?
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Post by fuzzysnuggleduck »

It was more of a diagnosis issue. I was just curious as to what RCA voltage the LOC was providing because the amp has a usable range of input voltage. The gain knob on the amp is there to tell the amp what voltage to expect, basically.
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packersfan
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Post by packersfan »

system sounds good but cant even get to 1/2 way on volume, if i turn doen the gain speakers shut off. Gain is around half way. basically every click from the beginning gets louder. I cant quite it down like it was in stock?
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Post by walker01s10 »

Need alittle help

Woofer JL 12w6 dual 4ohm voice coils
I can wire them 8 ohm or 2ohm

Amp Ti 600.2

If I wire the sub 8 ohm then hook it bridge to the amp would that give me a 4 ohm load?

Or should I wire the woofer 2 ohm then hook it bridged to the amp and if I did this what would the out put be??

4 ohm bridged is 600watts

Or how should I hook it up and try to figure out what the gain should be set at.
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deathcloud
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Post by deathcloud »

I don't know about the ti 600.2 but for the zx350 it says it can handle 2 ohms (current limited) which means I believe that the current is limited to 400 rms.

Now I don't want to tell you that you can do it because it doesn't say it can handle 2 ohms in the manual but with that sub you are going to be able to only wire it 2 ohms or 8 ohms.....

Someone else can verify it for me if you can run a sub at 2 ohms on the ti 600.2 or if you can't. But I dunno if the current gets limited. I don't want you to blow up your amp either by it trying to draw too much and then get too hot and fry.

But if you can then wire your sub for 2 ohm and then bridge the ti 600.2 and then DMM it for 36 volts and you should be set.
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walker01s10
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Post by walker01s10 »

I was kinda thinking the same thing wire the sub 2 ohm then bridged to the amp.

sqrt(600*2)= 34.64 volts
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deathcloud
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Post by deathcloud »

Yea u have the right idea. I just dont kno if u can go down to 2 ohms with that amp. Im sure that a lot of people here have had that amp and can tell u if it is possible. For fear of damaging the amp i would wait and see what people say before u try it.
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walker01s10
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Post by walker01s10 »

Well I'll be hooking them up today this way since no one else has responded and see what happens. And to try to be on the safe side I'm going to lower wattage alittle.

sqrt(2*500)= 31.62

Now if anyone else could answer this question that would be great or have an idea of what I should do please tell me.

Deathcloud thanks for your input
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Stryker
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Post by Stryker »

You can wire it for 2 ohms. I ran a 600Ti with a 2ohm sub load for 5 years and never had a problem. Gain was set at around half and I used some bass boost too. You should have no problems. Your sub will see about 600 watts and possibly more with musical peaks. Just remember you will generate more heat and draw more current off your electrical system as this is an A/B class amp and they are not terribly efficent at 2 ohms. If I was you I would strap 2-600's to your one sub and run 4ohm's to each amp. I'm a power hungry mutha :) GL hope this answers your question.
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Post by oldskoolmseriesfan »

with my ms275
sqrt*(75wx4ohms)=17.32 volts right?

and do I have my bass -mid- and treble set to flat? Im assuming yes, but just want to make sure.
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stipud
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Post by stipud »

oldskoolmseriesfan wrote:with my ms275
sqrt*(75wx4ohms)=17.32 volts right?

and do I have my bass -mid- and treble set to flat? Im assuming yes, but just want to make sure.
Yes and yes.
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Post by oldskoolmseriesfan »

HOLY CRAP :shock: :shock: :shock: What a difference, it is insanely loud and clean :metal: I only have front stage at the moment and cant wait to get some low end to blend with my punchy 6.5's :dj:
I actually understand this, now that Im back in school :lol:
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ShockTherapy
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Re: Gain setting with DMM

Post by ShockTherapy »

VW337 wrote:Find the rated power of your amplifier per channel.

Do the math to calculate the target voltage you need in order to adjust properly with your DMM.

root(wattage * speaker load) = voltage


Now, play a 60 Hz or 50 Hz 0dB sine wave, and turn your HU up to just below clipping, which should be about 3/4 - 7/8 of the way up. Set your DMM to Volts AC, and measure across the amplifier's speaker output terminals while the speakers are disconnected. Turn to gain up until you get to your calculated Volts AC.

I appreciate this tutorial. Now I was wondering... You say to take the rated wattage and multiply that by the speaker load. I'm an electrician so I understand most of this. My birth sheet for my amp shows that the Arc audio 4150CXLR is rated at 80x4 at 4ohm but actually produces 108x4. Do I use the rated output or the actual output? I assume I would use the actual output but wanted to clarify.
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