# RCA output voltage test on Alpine 9887



## placenta (Feb 2, 2008)

I expect a lot of people to tell me how untechnical this test is. So if you think it's wrong, do you own test. I would love some more professional testing from people that know what they're doing. 

My biggest question.. *why with my deck maxed at 35 volume, could my RCA's only manage about 1.5V RCA output voltage?* Where does that 4V rated signal magically come in? This explains a lot to me about my weak sub output, and why I had to put my sub amp gains up to 1.5V for it to sound halfway decent. 

Watch the video, make the call.

http://74.220.202.31/~bellbott/rcaouts.wmv


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## azngotskills (Feb 24, 2006)

FoxPro5 aka B-squad did the exact same testing on his Pioneer P9 or Eclipse CD8053 and results were interesting ....let me dig up the thread

EDIT: I cant seem to find the original thread but here is his test data. Maybe he can chime in



FoxPro5 said:


> I tested my P9 and here's what I found:
> 
> 12.4v. Hi/tweeter channel. Volume level, voltage
> -20, .1
> ...


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## placenta (Feb 2, 2008)

i gotta go to bed now. looking forward to any replies tomorrow morning.


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## kyheng (Jan 31, 2007)

By looking at your test, maybe we can conclude that Pre-out1, pre-out2 and pre-out3 voltage add together to get 4V? By looking at what you do, I thinking of getting a DMM to measure my P9650 which claims to have 6.5V pre-outs. 
Anyway the HU's psecs are somewhat misleading : with 4V pre-outs or 5V pre-outs...


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## sonicnirvana (Jan 6, 2008)

Couple things come to mind. Maybe you should try a Test CD with a known level. I know many of my CD's levels are all over the place. So that we can all be on the same page, maybe we can find a 0db Test tone WAV file that we all could use. 

Also, do you have the Defeat On? If it is, then one last thing would be to try a reset. I had a previous Alpine HU (not the 9887) that would go flaky and the the levels would get really low. A reset would cure the problem, but then I would lose all my settings.

I will try to test mine tonight and compare to yours. I found a 0 Db 1Khz test tone and will try that.


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## Candisa (Sep 15, 2007)

To my common sense, the only way to measure a sound devices (doesn't matter if it's a head-unit or a linedriver/crossover/amplifier/processor/...) voltage output, is by checking with a scope and some 0dB frequency tracks where the device is on it's limit of just not clipping on any audible frequency... WITH the loads you'll use connected (speakers/subwoofers in the case of an amplifier, linedrivers/crossovers/processors/amplifiers in case of a head-units pre-out, even on the outputs that you're not measuring) and all equalizer/crossover/boost/loudness settings off/flat!

Then, with still the load connected, play a 0dB pink noise track on that volume level and check the output voltage with a scope.

The spec'd output voltage of a head-unit's pre-outs is mostly the voltage it can reach on the least clipping sensitive frequency, maxed out, wich will be a lot higher than what the head-unit will produce playing a non-clipping pink noise track!


Please note that altough a head-units pre-out rms voltage isn't unimportant, you shouldn't pay *too* much attention to it. Sure it helps to minimize the effect of picked up noise in the RCA cables, and having the gains low reduces noise, but good quality, well shielded RCA running as far as possible from everything else and amplifiers with a low noise floor does the same thing!

A headunit with a nice stable flat frequency response is more important than a high pre-out voltage!

greetz,
Isabelle


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## typericey (May 13, 2006)

placenta said:


> I expect a lot of people to tell me how untechnical this test is. So if you think it's wrong, do you own test. I would love some more professional testing from people that know what they're doing.
> 
> My biggest question.. *why with my deck maxed at 35 volume, could my RCA's only manage about 1.5V RCA output voltage?* Where does that 4V rated signal magically come in? This explains a lot to me about my weak sub output, and why I had to put my sub amp gains up to 1.5V for it to sound halfway decent.
> 
> ...


i don't have an answer to your voltage question, but i can relate to your weak sub complaint. i have my 9887 connected to a 4 channel amp bridged to 3 (front stage and sub). the gains for the front stage are at minimum while the gains for the sub are past midway. and the subwoofer volume on the 9887 are on +12 for SQ (normal listening levels) and maxed out at +15 if i feel stupid.


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## Candisa (Sep 15, 2007)

Maybe a bit of an obvious reply, but something that is forgotten very much: connecting the sub in or out of phase can be a world of difference 

greetz,
Isabelle


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## grampi (Jun 29, 2007)

Per my phone discussion with a URS repair tech the other day, you can't measure the preamp output using a DMM. I did the same thing with my 9887 when I got no sound from my system. I inserted a CD, turned the volume up to 35, and with the RCA cables disconnected I checked the preamp output on the jacks on the rear of the 9887 and the DMM read 0 volts AC. It wasn't even reading millivolts so naturally I thought the preamp outs on the HU were dead. They weren't. I sent the unit in the URS for repair and they checked the preouts using an O-scope, and also by connecting it to the same amp I have and the unit checked out fine. They are sending the HU back and obviously have something else wrong with my system and further troubleshooting will be needed. But to reply to the OP, unless you have an O-scope, you can't measure the preouts.


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## chad (Jun 30, 2005)

Candisa said:


> To my common sense, the only way to measure a sound devices (doesn't matter if it's a head-unit or a linedriver/crossover/amplifier/processor/...) voltage output, is by checking with a scope and some 0dB frequency tracks where the device is on it's limit of just not clipping on any audible frequency... WITH the loads you'll use connected (speakers/subwoofers in the case of an amplifier, linedrivers/crossovers/processors/amplifiers in case of a head-units pre-out, even on the outputs that you're not measuring) and all equalizer/crossover/boost/loudness settings off/flat!
> 
> Then, with still the load connected, play a 0dB pink noise track on that volume level and check the output voltage with a scope.
> 
> ...




A breath of fresh air, thank you for not making me type that


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## Candisa (Sep 15, 2007)

:blush:


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## chad (Jun 30, 2005)

grampi said:


> Per my phone discussion with a URS repair tech the other day, you can't measure the preamp output using a DMM. I did the same thing with my 9887 when I got no sound from my system. I inserted a CD, turned the volume up to 35, and with the RCA cables disconnected I checked the preamp output on the jacks on the rear of the 9887 and the DMM read 0 volts AC. It wasn't even reading millivolts so naturally I thought the preamp outs on the HU were dead. They weren't. I sent the unit in the URS for repair and they checked the preouts using an O-scope, and also by connecting it to the same amp I have and the unit checked out fine. They are sending the HU back and obviously have something else wrong with my system and further troubleshooting will be needed. But to reply to the OP, unless you have an O-scope, you can't measure the preouts.


So you got your unit back... and there was nothing wrong with it?


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## Candisa (Sep 15, 2007)

Hmmm, with a DMM, you can't measure real results, since it's not made to measure at a wide range of frequencies, but it should be useable to measure at 50-60Hz (that's what it's made for in AC mode!), so I think it's quite odd that you didn't even measure millivolts with a CD (you should think there has to be some 50-60Hz information in almost any song?), but they did measure output with a scope... 

Did you happen to measure at an output that has a high-pass crossover, or a very very low frequency low-pass crossover activated on?

greetz,
Isabelle


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## durwood (Mar 7, 2007)

Most of the good stuff was already mentioned.

Another thing about DMM's and why you have to be careful when checking AC voltages...they are usually bandlimited to a particular frequency range. Go check out some Fluke specs and you will see what I mean. They can give you bogus data, not to mention you have no idea if the signal is clipping, that's what an o'scope is for. 

One more thing, they have to leave headroom on the outputs for EQ Boost useage if the headunit has it built in.


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## chad (Jun 30, 2005)

Candisa said:


> Hmmm, with a DMM, you can't measure real results, since it's not made to measure at a wide range of frequencies, but it should be useable to measure at 50-60Hz (that's what it's made for in AC mode!), so I think it's quite odd that you didn't even measure millivolts with a CD (you should think there has to be some 50-60Hz information in almost any song?), but they did measure output with a scope...
> 
> Did you happen to measure at an output that has a high-pass crossover, or a very very low frequency low-pass crossover activated on?
> 
> ...


I have generally found that if a meter has the capability of measuring frequency then it has a broad enough response to measure an audio frequency RMS voltage.

BUT... RMS!!!!! RMS voltage will continue to increase well into clipping till it's a square waveform! So without a scope you will not see P-P voltage, the clip point, and so on. 

You need a scope to do it, and a load does not hurt either, even for pre-outs.


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## Candisa (Sep 15, 2007)

chad said:


> I have generally found that if a meter has the capability of measuring frequency then it has a broad enough response to measure an audio frequency RMS voltage.


That makes me wonder even more why he didn't measure a single millivolt on his DMM


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## durwood (Mar 7, 2007)

Candisa said:


> That makes me wonder even more why he didn't measure a single millivolt on his DMM


Depends what he was using-testones or music and at what level?

Here are some examples of why DMM's might not be accurate if measuring higher AC frequencies.

Fluke Model 87



> Voltage AC Maximum Voltage: 1000V
> Accuracy: Fluke 83 V: ±(0.5%+2)
> Fluke 87 V: ±(0.7%+2) True RMS
> AC Bandwidth Fluke 83 V: 5kHz
> ...



Fluke 115



> AC millivolts1 true-rms Range: 600.0 mV
> Resolution: 0.1 mV
> Accuracy: 1.0 % + 3 (dc, 45 Hz to 500 Hz)2.0 % + 3 (500 Hz to 1 kHz)
> 
> ...


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## t3sn4f2 (Jan 3, 2007)

How much is lost from the long RCA run to the trunk?


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## placenta (Feb 2, 2008)

Candisa said:


> Maybe a bit of an obvious reply, but something that is forgotten very much: connecting the sub in or out of phase can be a world of difference
> 
> greetz,
> Isabelle


I've been trying to understand that. How changing phase can change the sound so much. Plus I been changing my crossover slopes too, and I heard that also changes phase?


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## placenta (Feb 2, 2008)

grampi said:


> Per my phone discussion with a URS repair tech the other day, you can't measure the preamp output using a DMM. I did the same thing with my 9887 when I got no sound from my system. I inserted a CD, turned the volume up to 35, and with the RCA cables disconnected I checked the preamp output on the jacks on the rear of the 9887 and the DMM read 0 volts AC. It wasn't even reading millivolts so naturally I thought the preamp outs on the HU were dead. They weren't. I sent the unit in the URS for repair and they checked the preouts using an O-scope, and also by connecting it to the same amp I have and the unit checked out fine. They are sending the HU back and obviously have something else wrong with my system and further troubleshooting will be needed. But to reply to the OP, unless you have an O-scope, you can't measure the preouts.



I had zero volts also, until I found a proper ground in my trunk. If I can't measure them, what was I seeing?


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## chad (Jun 30, 2005)

t3sn4f2 said:


> How much is lost from the long RCA run to the trunk?


Very, very little.


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## chad (Jun 30, 2005)

placenta said:


> I had zero volts also, until I found a proper ground in my trunk. If I can't measure them, what was I seeing?


Whoa, you are measuring from center pin to chassis ground?


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## chad (Jun 30, 2005)

placenta said:


> Plus I been changing my crossover slopes too, and I heard that also changes phase?


Shoulda done a multi quote but oh, well. Please keep in mind that Phase and Polarity are different things, the only correlation is that a polarity change is a 180 degree phase shift.

2 sources can be 1 degree OUT OF PHASE


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## placenta (Feb 2, 2008)

chad said:


> Whoa, you are measuring from center pin to chassis ground?


yes. 
RCA center pin with my Fluke + lead
my Fluke - lead of multimeter went straight to a ground bolt in my trunk


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## chad (Jun 30, 2005)

placenta said:


> yes.
> RCA center pin with my Fluke + lead
> my Fluke - lead of multimeter went straight to a ground bolt in my trunk


But you get nothing from the sleeve to pin?

Very odd. Does the cable have the sleeve attached at both ends?


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## placenta (Feb 2, 2008)

chad said:


> But you get nothing from the sleeve to pin?
> 
> Very odd. Does the cable have the sleeve attached at both ends?


you mean the outer metal of the RCA for ground? I couldnt get any readings from that.


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## chad (Jun 30, 2005)

placenta said:


> you mean the outer metal of the RCA for ground? I couldnt get any readings from that.


Exactly, is that outer jacket attached at both ends of the cable?

Gotta run to another building BRB.


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## 60ndown (Feb 8, 2007)

chad said:


> Phase and Polarity are different things, the only correlation is that a polarity change is a 180 degree phase shift.
> 
> 2 sources can be 1 degree OUT OF PHASE


i learned something new today, no idea how to implement it, but i heard it.


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## Candisa (Sep 15, 2007)

chad said:


> Shoulda done a multi quote but oh, well. Please keep in mind that Phase and Polarity are different things, the only correlation is that a polarity change is a 180 degree phase shift.
> 
> 2 sources can be 1 degree OUT OF PHASE


Completely correct. When you are using a 12dB/oct crossover, the drivers will be 180° out of electric phase, wich means, if you are using the right frequency, mount the speakers with the mounting flanges parallel to eachother in a baffle, and the motors of the speakers at the same distance from your ears, you have to switch polarity of one of them, to have them in acoustic phase.

In-car, you can try to predict how the acoustical phase will react, but it due to the different path lengths and angles, it's a matter of experimenting.

For example, I have 18dB/oct crossovers between sub, midbass and mids, and 24dB/oct crossovers between mids and tweeters. *Theoretically*, I should be fine with this slopes...

I have my tweeters on the dashboard, vertically, facing towards the rear. The mids will be right beneath them, so when I connect them the same way as the tweeters (0° phase difference), it should be in phase since a 24dB/oct crossover means a 360°=0° phase switch. 
My midbass woofers will be in my doors, slightly angled, but close to facing eachother. Their axis is on + or minus 90° compared to the mids+tweeters, so it should turn out fine, since a 18dB/oct crossover means a 270°=-90° phase switch. I might experiment with polarity, since I cannot predict if they have to be normally connected (= -90° phase switch), or connected with inversed polarity (=-90°+180°=90° phase switch).
My sub will be in the back, facing forward, so with exactly the same story as the midwoofers, an 18dB/oct slope should to fine... *theoretically*

In practice, it's just a matter of experimenting. Everybody has the ability to create a 180° phase switch on a driver. When you have a crossover/processor with different slope settings, a 90° phase switch on a driver is also possible (uneven order slopes), and when you have time alignment, you could measure (RTA) on what frequency, the frequency response of the driver groups cross eachother and calculate what delay you'll need to create whatever phase difference you want to get in acoustical phase.

greetz,
Isabelle

Fi-ew...


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## placenta (Feb 2, 2008)

chad said:


> Exactly, is that outer jacket attached at both ends of the cable?
> 
> Gotta run to another building BRB.


its the metal that clips to the outer edge of the RCA jack. on both ends.


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## Candisa (Sep 15, 2007)

Are you sure both ends of the RCA cable are connected to the shielding and/or mass-wire? A lot of RCA cables don't have both ends connected to the shielding to prevent ground loops!

greetz,
Isabelle


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## chad (Jun 30, 2005)

Candisa said:


> Completely correct. When you are using a 12dB/oct crossover, the drivers will be 180° out of electric phase,
> Fi-ew...


Only at the crossover point though, it does not shift the phase of the whole passband. 



placenta said:


> its the metal that clips to the outer edge of the RCA jack. on both ends.


Right, are both metal sleeves electrically connected within the cable. I know it sounds like a stupid question, but bear with me.

Better yet, with the system OFF, what's the resistance between the pin and sleeve (shield) at the amplifier?


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## Candisa (Sep 15, 2007)

chad said:


> Only at the crossover point though, it does not shift the phase of the whole passband.


True, but on what points is being in phase important to have a nice blend?  

greetingz,
Isabelle


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## chad (Jun 30, 2005)

Candisa said:


> True, but on what points is being in phase important to have a nice blend?
> 
> greetingz,
> Isabelle


Bingo!

Phase is really only relavent if you have another source to compare it to. 

The best one is the folks that complain about the phase response of a particular enclosure and stand on that as an argument. Is it in phase with the next passband? Yes? Roll with it!


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## grampi (Jun 29, 2007)

chad said:


> So you got your unit back... and there was nothing wrong with it?


They're shipping it out today. They said their was nothing wrong with it as it was checked out both by checking with an O-scope and connecting it to a known working system.


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## grampi (Jun 29, 2007)

durwood said:


> Depends what he was using-testones or music and at what level?
> 
> Here are some examples of why DMM's might not be accurate if measuring higher AC frequencies.
> 
> ...


I was using just a regular ol' music CD and I had the volume control maxed out. I wasn't looking for 4 volts, I was looking for ANY voltage to see if the preout circuit was dead. I mistakenly thought it was because my DMM read absolutely 0 volts. It apparently depends on what DMM you're using as to whether or not you'll see ANY voltage.


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## grampi (Jun 29, 2007)

placenta said:


> yes.
> RCA center pin with my Fluke + lead
> my Fluke - lead of multimeter went straight to a ground bolt in my trunk


I took my readings straight from the female RCA jacks on the back of the HU. Positive to the center pin jack, and the negative on the outer portion of the jack, and I read 0 volts.


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## placenta (Feb 2, 2008)

grampi said:


> I took my readings straight from the female RCA jacks on the back of the HU. Positive to the center pin jack, and the negative on the outer portion of the jack, and I read 0 volts.


next time try ground to a bolt in trunk instead. i had exact same experience. and it took me a few bolts to find one that worked.


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## nauc (Sep 12, 2006)

i scoped and DMMed my 9833 rca outs, got 5v at 50hz, 100hz, 400hz, 1k, and 10k

need to do my 9887


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## grampi (Jun 29, 2007)

placenta said:


> next time try ground to a bolt in trunk instead. i had exact same experience. and it took me a few bolts to find one that worked.


Why would that make any difference? The HU is grounded to the chassis.


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## placenta (Feb 2, 2008)

my amp is bad. im going to update my master thread...


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## grampi (Jun 29, 2007)

placenta said:


> my amp is bad. im going to update my master thread...


At least you know what's wrong with your system now. I'm over 3 months into my install and still don't know what's wrong with mine. My 9887 just got a clean bill of health and I've replaced the amp. I've either got a problem with my RCA cables or my passives. I don't know what else the problem could be. This crap is driving me nuts!


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## placenta (Feb 2, 2008)

grampi said:


> At least you know what's wrong with your system now. I'm over 3 months into my install and still don't know what's wrong with mine. My 9887 just got a clean bill of health and I've replaced the amp. I've either got a problem with my RCA cables or my passives. I don't know what else the problem could be. This crap is driving me nuts!


im depressed yet relieved at the same time. not knowing is the worst.


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## grampi (Jun 29, 2007)

placenta said:


> im depressed yet relieved at the same time. not knowing is the worst.


I know what you mean. Not knowing is the absolute worst!


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## FoxPro5 (Feb 14, 2006)

The real reason why I measured mine was to see how much voltage the deck was putting out at various volume levels, not to prove the manufacturers are liars. As I've found with a couple different decks, they really don't start kicking until around 90% max volume.

Also, keep in mind that with my tests on the P9, as I later learned, you don't see a full 4v until you've maxed out the EQ.


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## t3sn4f2 (Jan 3, 2007)

FoxPro5 said:


> The real reason why I measured mine was to see how much voltage the deck was putting out at various volume levels, not to prove the manufacturers are liars. As I've found with a couple different decks, *they really don't start kicking until around 90% max volume*.
> 
> Also, keep in mind that with my tests on the P9, as I later learned, you don't see a full 4v until you've maxed out the EQ.


LOG curve.


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## FoxPro5 (Feb 14, 2006)

grampi said:


> I was using just a regular ol' music CD and I had the volume control maxed out. I wasn't looking for 4 volts, I was looking for ANY voltage to see if the preout circuit was dead. I mistakenly thought it was because my DMM read absolutely 0 volts. It apparently depends on what DMM you're using as to whether or not you'll see ANY voltage.


No, it depends on the music because the waveform, which drives the voltage, is constantly in flux. 

Plus, you need to consider the RMS of the music track. Repeat the test with a "hot" track and you might see some voltage. But if you use a well recorded track say from 1985, then it might be at -20 dB. 

Redo your test with a 0dB sine at 50 hz that you made from NCH Tone generator.


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## FoxPro5 (Feb 14, 2006)

t3sn4f2 said:


> LOG curve.


Sir yessir! My point exactly. Totally parabolic and ****, dude!


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## FoxPro5 (Feb 14, 2006)

And the DMM my be sort of invalid, but it still can be reliable.


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## rekd0514 (Sep 24, 2006)

I dunno if this was mentioned already or not, but don't Alpine decks have to have their subwoofer pre out maxed to 15 to see full pre out voltage. I remeber reading that a few times. Sorry if we have already established this.


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## chad (Jun 30, 2005)

rekd0514 said:


> I dunno if this was mentioned already or not, but don't Alpine decks have to have their subwoofer pre out maxed to 15 to see full pre out voltage. I remeber reading that a few times. Sorry if we have already established this.


I do not believe it was established but very true.

I don't want to tell you where my sub gain on my amp is at  But let's just say I tune with the sub control down a bit in case something needs it. Or, I just wanna cut loose.


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## placenta (Feb 2, 2008)

chad said:


> I don't want to tell you where my sub gain on my amp is at  But let's just say I tune with the sub control down a bit in case something needs it. Or, I just wanna cut loose.


come on, tell us where its at.. 

i always feel like im talking to a red haired guy when you post..


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## chad (Jun 30, 2005)

placenta said:


> come on, tell us where its at..
> 
> i always feel like im talking to a red haired guy when you post..


Pinned


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## FoxPro5 (Feb 14, 2006)

<---- that guy's sub wanngs, yo!


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## placenta (Feb 2, 2008)

chad said:


> Pinned


what does pinned mean? oh i thought you mean about your hair.. LOL gain pinned.. got it.


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## sonicnirvana (Jan 6, 2008)

OK, I have run some bench tests on all of my Alpine HU's. Used a 1 Khz Sine wave at 0db. I ran them all through the scope and the DMM for the front outs only. Used the scope to check for clipping, the DMM to get RMS voltage. Bottom line is my 9887 can put out 4 Volts.

Here is the weird thing. When I measured it in my truck, my 9887 clipped at Volume 24, Imprint OFF, Defeat ON. On the bench, no clipping at max volume. Maybe some crappy RCA's? Dunno. I am actually in the process of replacing my RCA's which is why I have the HU out, so I will check it again with the new Knu RCA's.

Anyway here are the results I got. Keep in mind that the Scope is going to show peak to peak voltage, whereas the DMM is RMS. So divide the DMM/RMS by .707 and you will get the scope readings. If you are getting 0 volts with a DMM at full output, something is wrong. Also, my sub output rocks, so I didn't feel the need to measure it. FWIW my 9857 clips at volume 31...


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## placenta (Feb 2, 2008)

Thanks for the tests and confirmation that there's nothing wrong with 9887 RCA outputs.

funny how I bet most people never go above volume 30 on their 9887.. and thats only 2.34V.. so whats the point of having 4V then?


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## Diru (May 23, 2006)

placenta said:


> Thanks for the tests and confirmation that there's nothing wrong with 9887 RCA outputs.
> 
> funny how I bet most people never go above volume 30 on their 9887.. and thats only 2.34V.. so whats the point of having 4V then?



I little less than 3db.





By the micky fricking way, when you youtsssss are measuring the output of these forementioned head unit pres, are you terminating them into the correct non-reactive impedance loads. Cause If you are not then your numbers are invalid.

I did not say incorrect, just invalid. Depending on the output impedance of some decks may and could change these fancy fricken numbers your tossing out there as the gospel.

Errors as great as 50% could happen.

Meaning to the world at large your measurments are up to 3db`s off the mark.

Which means not a damned thing unless your name is Chad and this is only car audio.......


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## FoxPro5 (Feb 14, 2006)

sonicnirvana said:


> OK, I have run some bench tests on all of my Alpine HU's. Used a 1 Khz Sine wave at 0db. I ran them all through the scope and the DMM for the front outs only. Used the scope to check for clipping, the DMM to get RMS voltage. Bottom line is my 9887 can put out 4 Volts.
> 
> Here is the weird thing. When I measured it in my truck, my 9887 clipped at Volume 24, Imprint OFF, Defeat ON. On the bench, no clipping at max volume. Maybe some crappy RCA's? Dunno. I am actually in the process of replacing my RCA's which is why I have the HU out, so I will check it again with the new Knu RCA's.
> 
> Anyway here are the results I got. Keep in mind that the Scope is going to show peak to peak voltage, whereas the DMM is RMS. So divide the DMM/RMS by .707 and you will get the scope readings. If you are getting 0 volts with a DMM at full output, something is wrong. Also, my sub output rocks, so I didn't feel the need to measure it. FWIW my 9857 clips at volume 31...


Thanks for posting your results. Great info right there. Glad to see I haven't been taking crazy pills all along.


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## t3sn4f2 (Jan 3, 2007)

placenta said:


> Thanks for the tests and confirmation that there's nothing wrong with 9887 RCA outputs.
> 
> funny how I bet most people never go above volume 30 on their 9887.. and thats only 2.34V.. *so whats the point of having 4V then?*


Preamp headroom for low recordings when using your head unit with a less then perfect amp that needs at least the standard 2 volt input voltage to maintain an inaudible noise floor by keeping the gains down.


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## lostdaytomorrow (Jan 26, 2007)

Diru said:


> I little less than 3db.
> 
> 
> 
> ...


I don't understand this post. 

Is that a personal attack on Chad also?


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## Diru (May 23, 2006)

Diru said:


> I little less than 3db.
> 
> 
> 
> ...





lostdaytomorrow said:


> I don't understand this post.
> 
> Is that a personal attack on Chad also?


 

No its not an personal attack on Chad.

The post in only about the importance of making measurements correctly.

But , in the end this is just car audio.

Just as more or less the same as the reference "It's only 2 meters" to Chad and myself, plus a few more that won't or choose not to reveil they are amatuer radio hobbiest[i.e. Ham radio operators].

Further more, I enjoy pissing into a strong breeze, cause I'm crazy like that.


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## chad (Jun 30, 2005)

Diru said:


> Further more, I enjoy pissing into a strong breeze, cause I'm crazy like that.


And I've finally convinced to close his mouth while doing so! Tough for him to hold his breath for that long though


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## placenta (Feb 2, 2008)

placenta said:


> my amp is bad. im going to update my master thread...


wanted an update in here since its a 9887 RCA thread... McIntosh cannot find anything wrong with my amp so far with their bench tests. 

On the 9887 deck... im using an aftermarket subaru harness. That harness had a black ground wire. I hooked the deck to it, rather than run the decks black to a separate ground. Theres no way this could cause an intermittent noise is there?


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## grampi (Jun 29, 2007)

placenta said:


> wanted an update in here since its a 9887 RCA thread... McIntosh cannot find anything wrong with my amp so far with their bench tests.


I just pulled my amp out of my vehicle yesterday and sent it in to be checked out and my biggest fear is they'll say there's nothing wrong with it. If that's the case, I'll be at a complete dead-end with my system. 

I'm not getting any output whatsoever from the amp to either my comps or my subs.

I've checked the preamp output signal from my HU by plugging in my Radio Shack mini-speaker right on the back of the HU so I know that's not the problem.

I've checked the preamp signal at the amp end of the RCA cables and the cables are good. 

I know the amp is receiving the remote turn-on signal as it turns on and the display window displays all its info. 

I know the amp is receiving power as I checked the power reading right at the amp's POS and NEG terminals. 

I took an ohm reading at the speaker outputs of the passive crossovers. The readings are the same for both channels; the mids read 3.5 ohms, and the tweets read .9 ohms. Not quite sure why the tweets are only reading .9 ohms, but I'm guessing it has something to do with the crossover. There doesn't appear to be any indication of a short.

I took an ohm reading of the subs (two 8 ohm subs connected in parallel) and they read 3.8 ohms. Again, no problem indicated there either.

I checked all of the possible different settings on the amp that would have an effect on its output and this didn't help.

Unless I'm overlooking something, I have checked my system from end to end and the only possible problem I can see is there is something wrong with the amp. If they tell me there's nothing wrong with the amp I'm done. If that ends up being the case, this problem is beyond my troubleshooting abilities and I will have no choice but to take my car to someone else to see if they can figure out what the problem is. I have never in my 20+ years of being involved with car audio had a problem that's been so perplexing.


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## placenta (Feb 2, 2008)

Dude, sounds like my headache too.. I think "grounds" can be the unknown source of many problems. I know my amp ground is solid, its under a big bolt with all the paint scraped off.. I am learning toward a deck problem now.


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## grampi (Jun 29, 2007)

placenta said:


> Dude, sounds like my headache too.. I think "grounds" can be the unknown source of many problems. I know my amp ground is solid, its under a big bolt with all the paint scraped off.. I am learning toward a deck problem now.


I was thinking ground problem too until I took my voltage measurement right at the amp's POS and NEG terminals and I read the system voltage. Is it possible to have a good enough ground for it to read like a good connection and yet not be a good enough of a ground for the amp to actually work? The last time I went to Lowe's I was looking for some of those star lock washers because those things really bite into the metal and make an excellent ground connection, but they didn't have any. I will look around at some other places and see if can find some of those. Maybe it's a grounding problem.


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## placenta (Feb 2, 2008)

Another cool thing I found out about the 9887. The crossovers affect the speaker outputs also, not just the RCA's. I never knew that. I found out when I attenuated my front RCA crossover to keep the voltage off, and my front stage off speaker outputs disappeared.


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## gangstajpimpin (Nov 25, 2008)

up..i have the same problem


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## raresvintea (Sep 17, 2010)

Sorry for reveleaning an old thread. An guy said that when he tested on bench, at home the max non clip volume was 31, but on the car there was much lower.

On my player when i hit 23/31 the sound becomens distorsonated. What can i do this way? To run another power from battery? Or what can i do?


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## placenta (Feb 2, 2008)

whoa. my 4 year old thread.


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## kyheng (Jan 31, 2007)

raresvintea said:


> Sorry for reveleaning an old thread. An guy said that when he tested on bench, at home the max non clip volume was 31, but on the car there was much lower.
> 
> On my player when i hit 23/31 the sound becomens distorsonated. What can i do this way? To run another power from battery? Or what can i do?


AC-DC convertor usually can supply a constant and stable power but does not mean a car electrical can supply that especially you are using the wire from stock....


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## chad (Jun 30, 2005)

kyheng said:


> AC-DC convertor usually can supply a constant and stable power but does not mean a car electrical can supply that especially you are using the wire from stock....


I have my specs around here from testing mine. It draws like, less than an amp when you dont use the speaker outs....and mine never clipped driving a 600 ohm load. 

Sent from my Sony Tablet S using Tapatalk 2


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