Amp output voltage very low?

[CaptNKILL 10+ year member]

I just installed my Eclipse SC6500 6.5" components and they are running off of a Kicker ZX200.2. They should be getting 70W RMS each, roughly. At 4ohms the voltage at the terminals on the amp should be 16.7V.

I set my HU volume at 25 (out of 35) and I set my gains so things are about as loud as I'm used to. I disconnected the speakers, hooked up the dmm and played a few different test tones (250, 500, 1000) and for some reason the voltage is reading very low. Around 4v at normal listening volume. It takes quite a bit of volume from the HU (around 20) to even get the dmm to read over 1v.

The speaker volume seems fine, its plenty loud... why would my dmm be reading the voltage so low? When I use the same dmm to check the voltage on my Infinity amp (312W @ 2ohm) it reads perfectly.

My multimeter is almost identical to this one:

I've tried setting it to 20vAC and 200vAC without any real difference in output.

I'm not sure if this is related, but I've also noticed that the mid bass seems to be lacking compared to my stock speakers running off of the HU (22RMS, 50W peak). The magnet on the stock speakers is like 1 inch in diameter and the things seem cheesy as hell... I have no idea how they put out as much mid bass as they do, but compared to them, my new $130 Eclipse comps running off of my new amp seem to be lacking in the low end.

When I tested this amp a month ago with some infinity 6x9s I noticed that there was absolutely nothing but highs. There were no mids or mid bass, but I figured it was because I just had the speakers sitting in the trunk. Now, I'm not so sure. My doors are sealed VERY well from the factory, with only a few tiny (less than quarter inch) holes on the inner door panel. So with my comps installed it shouldn't be a lack of pressure for the driver.

Anyone have any ideas for the low voltage or the lack of mid bass? Is it possible for an amp to be defective in a way that causes the mids to be very quiet?

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[king ranch 5,000+ posts]

my kicker did the same thing its a zx1500 and the volts start decreasing on the dmm once i go up to a certain point on the gain about halfway gain and the volts start decreasing. everyother amp the volts continue to go up but just distorted power but the dmm doenst know if its distorted or not so the volts should continue to go up.

 

[CaptNKILL 10+ year member]

my kicker did the same thing its a zx1500 and the volts start decreasing on the dmm once i go up to a certain point on the gain about halfway gain and the volts start decreasing. everyother amp the volts continue to go up but just distorted power but the dmm doenst know if its distorted or not so the volts should continue to go up.

That doesn't sound like the same problem I'm having. When the gains are all the way down I get 0v. As I raise it, it goes up .1, .2, .3 etc... it doesn't have any drops or spikes in voltage. The voltage is just extremely low all around.

I'm no electrician, but it seems like if a multimeter measures voltage and its reading 4v, then your speakers will be getting 4v.

 

[CaptNKILL 10+ year member]

Do people just go to sleep while browsing these forums? All the time I notice users in "currently active users viewing this thread" that just sit there for hours without ever posting... lol

 

[Tehgregzor 10+ year member]

An amplifier's job is to turn voltage into wattage. If you gave your speakers 12 full volts* they would fry. You are giving your speakers low voltage, high wattage. I bet if you tested the wattage it would be close, if not right on.

* depending on amperage

 

[CaptNKILL 10+ year member]

An amplifier's job is to turn voltage into wattage. If you gave your speakers 12 full volts* they would fry. You are giving your speakers low voltage, high wattage. I bet if you tested the wattage it would be close, if not right on.
* depending on amperage

When you set your gains using a DMM you measure the output voltage of the amp. People have been doing this for years.

My sub takes around 24v at 2ohms and the DMM shows that number almost exactly.

My comps should be getting around 16.7v at 4ohms each from my amp (70w) but when I measure it with the dmm, the voltage is around 4v.

I'm not sure what you're trying to tell me.

 

[thevic24 5,000+ posts]

try setting it with a 50 hz test tone, just unplug the drivers. ive had these issues in the past using 200 hz test tones and using a 50hz tone seemed to work out better. also have your car running to give the amps the extra power.

 

[CaptNKILL 10+ year member]

try setting it with a 50 hz test tone, just unplug the drivers. ive had these issues in the past using 200 hz test tones and using a 50hz tone seemed to work out better. also have your car running to give the amps the extra power.

I can't send it a 50hz test tone, its an amp for my component speakers with the high-pass set at 80hz...

I did try some bass test tones and the readings weren't much different... just lower because of the high-pass.

 

[CaptNKILL 10+ year member]

So, no ideas as to why a 2 channel amp would be outputting an extremely low voltage when measured by a DMM?

 

[thch 10+ year member]

low signal is my guess. are you sure you don't have a filter on the input signal somewhere. either on the amp, or on the HU. if the HU has balence/fade, it might help to look at it as well. eg, if balence is nearly full left and you're trying to set the gain using the right channel you'll have a hard time.

 

[CaptNKILL 10+ year member]

low signal is my guess. are you sure you don't have a filter on the input signal somewhere. either on the amp, or on the HU. if the HU has balence/fade, it might help to look at it as well. eg, if balence is nearly full left and you're trying to set the gain using the right channel you'll have a hard time.

I've checked everything. My balance is set centered, my fader is all the way to the front (I don't need my rears), my polarity\phase is fine, I tried the crossovers on the HU and the amp at 80, 60 and OFF without any real change.

I thought maybe the amps weren't getting enough juice for some reason (only running 312w rms for my sub right now) so I checked my input voltages on both amps and at my normal listening volume with the car running they are getting 14.1v. So it isn't a lack of power.

All I can think is that the amp is having some sort of problem or maybe that 70w is ridiculously loud for me and I'm simply not turning the gains up enough... which I highly highly doubt. The highest I got the voltage to read was 7.5v while playing a 1000hz 0db test tone at a volume of 27. Normal music makes my ears bleed at that level.

I emailed Kicker about it a little while ago, so hopefully they can give me some suggestions.

I think I might try out a friend's amp tomorrow to see if the speakers sound any different or the voltages read correctly. If the speakers have better mids with his amp and the voltage reads fine then I most likely have a malfunctioning amp.

I have to say, I've been really surprised how little information there is around the web relating to low voltage readings on speaker outputs. It seems like either no one actually bothers measuring with a DMM or no one has the problem. //content.invisioncic.com/y282845/emoticons/crap.gif.7f4dd41e3e9b23fbd170a1ee6f65cecc.gif

Is there any chance that it could be my RCAs?

 

[helotaxi 5,000+ posts]

It's called efficient speakers. It's not a problem. You said yourself that the speakers get loud enough. You're running about 2 watts to them and guess what many times that's all you really need to get enough output for a sane person.

 

[thch 10+ year member]

oh, yeah, there's normally no reason to use a DMM for a speaker amp other then a safety check. nothing on the DMM measures "sounds good" after all! all the DMM does is give an estimate of power, and what you really want is something that sounds good and is safe.

 

[CaptNKILL 10+ year member]

It's called efficient speakers. It's not a problem. You said yourself that the speakers get loud enough. You're running about 2 watts to them and guess what many times that's all you really need to get enough output for a sane person.

I sort of figured it was something like that.

Any ideas as to why they seem to be lacking mid bass though?

The doors are pretty well sealed by a huge steel panel, but there are some small holes, especially right around the speaker (from the old rivets). Would this have a real big effect on the bass output of the speakers? The originals woofers were built directly into the mounting bracket so they were extremely well sealed.

I had my brother listen to my speakers without telling him what I thought and he said the same thing... the speaker's sound isn't very "full" and is lacking in the low end. It sounds like I have the 60-150hz range turned way down on an EQ, but I don't. Turning up the bass on the EQ on my head unit screws with the sound of the sub too much.

I actually found an old Sony crossover network from the early 90s in a pile of my old electronics, but from what I can tell its meant for an active setup and won't work for me. I don't know that it'd help anyway. It seems like the amp just doesn't want to put out any low end at all.

 

[CaptNKILL 10+ year member]

bump