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Topic: Whats wrong with my amp? (Read 2722 times) previous topic - next topic
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Whats wrong with my amp?

hi, im new to this forum and iv come here as i cannot find anything online to help me sus this out. i have a rather odd but large set-up. im running a Denon AVR 1908, which is running 24 speakers and 5 subwoofers - i know others will say thats wrong but its been running them all sweet as a nut now for about a year and a half, until this problem occured about 3 weeks ago. i will try to explain it as best i can.

3 weeks ago i noticed that my right channel had some slight crackling, this happened when listening to the radio, CD, etc all sources. i assumed it would go away itself assuming it was just static, but instead it steadily got worse and louder and became echoy, to the point where it was like listening to a half tuned radio station. so i then assumed it could have been a lose connection. i then disconnected all speaker cables, cut all the ends off and made fresh ones. hooked them all up again and it stopped crackling.

however, i put it on 2 days ago, and i noticed instantly that the bass was alot deeper than normal, i was running my MP3 player through the amp at the time so i just assumed it was the quality of the track, i dozed off, and when i woke up a few hours later, the bass was seriously loud, some of my surround speakers were actually making popping noises and the sound was echoy, i tuned it to the radio and all i got was complete static like there was no station tuned at all. last time it did this rather than switching it off and taking the plug out (which didnt help) i just ripped the plug out while it was on, and it seemed to solve it.

yesterday, it went just as bad, crackling started within seconds of it being on. so i ripped the plug out again, waited a few seconds, plugged it back in, and im sorry for my choice of words here but what happened next i s**t myself. a few bangs down my subs and complete static, i got the fright of my life.

iv tried changing the fuse in the plug it doesnt help. iv got it on now and its running like normal, for now. its only every so often this happens and im confused as to why?

yes i know this amp isnt designed to power all these speakers, but its never bothered it before.

iv read up on a few posts people had with denon amps and apparently the micro processor is a common failure in these amps, and for repairs the full main board would need replaced. but iv always known denon amps to be rather good so this would surprise me if it was an internal defect.

can anyone tell me whats causing this??

Whats wrong with my amp?

Reply #1 –
I'd say the controller for effects went berzerk. But yeah, when you connected all these speakers you probably helped.
TAPE LOADING ERROR

Whats wrong with my amp?

Reply #2 –
Quote from: hlloyge on
I'd say the controller for effects went berzerk. But yeah, when you connected all these speakers you probably helped.

fixed it. amp is not faulty after all

Whats wrong with my amp?

Reply #3 –
Please don't be a "fixed it".

How did you fix it?
Who are you and how did you get in here ?
I'm a locksmith, I'm a locksmith.

Whats wrong with my amp?

Reply #4 –
Quote
yes i know this amp isnt designed to power all these speakers, but its never bothered it before.
It's your amp and it's up to you, but depending on how the speakers are wired, you may be operating your AVR outside of it's specified operating conditions.  You can potentially overheat it and/or damage it. 

You need to understand what happens to impedance when you connect speakers in series or parallel.    When you connect two equal-impedance speakers in parallel the total impedance is half.    i.e. 2 8-Ohm Speakers in parallel is 4 Ohms.  This results in twice the current and twice the power (assuming the same applied signal/voltage).    Put enough speakers in parallel and you'll overload your amplifier.  Another way to think about it is that the 1st speaker isn't affected by adding the 2nd speaker in parallel...  It still receives it's original power and the 2nd speaker receives the same power also.

Two equal impedance speakers in series is half the total power (each speaker gets 1/4th the original power).        Series wiring is "safer" because you are getting less power from the amp and putting less stress on it.    But, if the speakers are not identical strange things can happen to the frequency response because speakers are not like resistors and the impedance varies over the frequency range. 

You can wire 4 identical speakers (or 16 speakers) in a series-parallel combination where the net impedance (and total power) is unchanged and the power is divided equally among the drivers.

If your subwoofers are active (with each having it's own built-in amplifier) this isn't an issue.    The line-level subwoofer output on your AVR can probably  drive 10 line-level inputs.    You do need to make sure they are all in-phase or the soundwaves will cancel and more woofers can result in less bass.

Whats wrong with my amp?

Reply #5 –
Quote from: DVDdoug on
Quote
yes i know this amp isnt designed to power all these speakers, but its never bothered it before.
It's your amp and it's up to you, but depending on how the speakers are wired, you may be operating your AVR outside of it's specified operating conditions.  You can potentially overheat it and/or damage it. 

You need to understand what happens to impedance when you connect speakers in series or parallel.    When you connect two equal-impedance speakers in parallel the total impedance is half.    i.e. 2 8-Ohm Speakers in parallel is 4 Ohms.  This results in twice the current and twice the power (assuming the same applied signal/voltage).    Put enough speakers in parallel and you'll overload your amplifier.  Another way to think about it is that the 1st speaker isn't affected by adding the 2nd speaker in parallel...  It still receives it's original power and the 2nd speaker receives the same power also.

Two equal impedance speakers in series is half the total power (each speaker gets 1/4th the original power).        Series wiring is "safer" because you are getting less power from the amp and putting less stress on it.    But, if the speakers are not identical strange things can happen to the frequency response because speakers are not like resistors and the impedance varies over the frequency range. 

You can wire 4 identical speakers (or 16 speakers) in a series-parallel combination where the net impedance (and total power) is unchanged and the power is divided equally among the drivers.

If your subwoofers are active (with each having it's own built-in amplifier) this isn't an issue.    The line-level subwoofer output on your AVR can probably  drive 10 line-level inputs.    You do need to make sure they are all in-phase or the soundwaves will cancel and more woofers can result in less bass.


all my speakers are running from the 4 main front channels. i have nothing connected to the centre or surround. my subs are individually connected to the main sub out. iv ran them like this for over a year and its never been an issue. and this time it wasnt an issue either. all i did to fix the problem was reset the micro processor. it sounds as good as new again. i wanted to avoid this as it takes me over an hour to set up and fine tune all my settings again, and i simply couldnt be bothered with this all again. but in the end rather than sending it away for costly repairs (which didnt need done) i just reset it. job done.

id give a run down of the full setup but its massively complicated to explain how iv done it. plus i do not want to end up making a post a mile long for you to read. if others are mind blown just by looking at how iv set it up, then explaining it will be even worse. but it works thats all i care about.
iv messed around with audio equipment since i was a lad over the years iv come to learn alot about them, as you say Ohms, ratings, amplifiers etc. i know how to overload an amp but i also know ways to hook up more speakers than stated it can handle and still not over load the amp. IM NOT TRYING TO SAY OR PRETENDING TO BE A MR KNOW IT ALL, its just been years of trial and error, tweaks etc etc iv learned from. i knew when i got this AVR what i wanted to do. i was looking into getting another one with a USB port for my external music players, phone, etc, but as USB compresses data it would not get the very best quality anyway. which is key to me.

when i first got this AVR it did lack a bit of "omph" compared to what it said in the specifications of what it could do. so i did some modifications to the main board which has enabled me to have the extra power needed for the AVR to drive all speakers. and the best bit is i can still add even more speakers to it if i wanted. although 24 is more than enough. i love my audio, and my setups. i like bass, volume, clarity, and quality. if an amp struggles to produce even half decent mids and highs i get rid of it just as quick as i get it. it will sound impossible i know that iv been able to do it, but you would have to see it to believe it. and hear it. it makes all other 7.1 and 5.1s look like dinky toys.

thanks for your replies but i wasted your and my time with this post. if admin are reading this feel free to delete it. thank you
 

Whats wrong with my amp?

Reply #6 –
Quote from: Neo63 on
i was looking into getting another one with a USB port for my external music players, phone, etc, but as USB compresses data it would not get the very best quality anyway. which is key to me.


As an aside, USB transmission does not "compress data". USB delivers the digital data to your system. If the player sending the "digital bits" is sending lossless audio (e.g., equivalent to CD, 16/44.1 or even hi-res audio if you have that, 24/96 or 24/192), then the USB vehicle as a means of transmission will deliver such "digital bits" equivalent to the original CD or hi-res files. And if your internal or external DAC will handle such bits, you're OK.  The transmission can be USB, S/PDIF, ethernet, or even WIFI without any degradation of the audio being transmitted.