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Troubleshooting the sub (PB1000) after AVR change

connta

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Recently i switched AVRs, went from Onkyo 646 to Denon x4700h, the results are mixed considering the price of Denon but oh well, life goes on.

In any case, everything was "fine" with Onkyo, didnt really notice anything out of the ordinary. Switched to Denon and when running Audyssey i noticed that the sub level was fluctuating kinda a lot (dont remember it being this way before). Onkyo is in service for 8 years, sub 2.5, and i tinkered a lot, my memory on how things were might not be correct.

So, the problem, on Audyssey SW lvl matching screen lets say the measurement is "centered" around 75 dB it will constantly jump up and down in a span of about 5 dB (72-77 constantly) and then it would go even further at times going down to 70 then back to 80. No clear pattern is observed but it looks like it does a big spike after a dip. It really isnt constant enough to draw conclusions. The spikes are easily felt next to being measured, the windows rattle just a bit when it happens.

Tried different cable, SW2 output on Denon, checked electrical socket with a checker, reports good ground and everything, ran SW signal from REW (thru Denon), unpacked old Onkyo and tried its level signal on SW. It is about the same, it fluctuates kinda a lot. I dont remember it being this way, sure sub will fluctuate the most during test signals but i remember it being around 1 dB for speakers and 3 dB for sub, dont remember sub dipping and spiking +- 10 dB. Watched some calibration process videos online and their subs are more in line with 3 dB fluctuation, didnt see any major spikes like mine.

Then i proceeded to do a near field measurement on the sub trying to avoid the room as much as possible and thats wheen i noticed theres a very slight hiss (rumble more exact) coming from the sub. Its doing so even without a signal cable plugged in. The rumble is present as long as the sub is active (its a SVS PB1000, it has standby) no matter the signal cable, when it hits standby the rumble stops. It is very low, i never noticed it before, you really have to put your ear to the cloth grille, 1 ft away and i cant hear it. Dont remember ever hearing it in 2.5 years with the sub. It doesnt react on volume at the back of the sub, cranked all the way up or down, the rumble stays the same level. The auto standby engages as expected, it isnt influenced by the rumble.

In normal conditions, music, movies, games, i dont really see an issue. Theres a slight out of place LFE explosion from time to time but that seems to be down to the rips/masters since they are reproducible exactly every time. When i hear something like that i rewind the scene couple of times to see if its constant and it always is.

Objectively, i cannot say when the "issue" started, it really isnt apparent in real content. Im not sure if the rumble (hiss) is connected to the spikes and dips during calibration or was it there since forever just not noticed. I do know that i did fumble a bit when changing AVR, i didnt turn off the sub on the hard switch before unplugging the signal cable on AVR side. AVR was on standby (electricity plugged in, video passthru not enabled, no ARC, CEC or anything, red LED). The sub was also plugged in but it might have been on active standby (blue led) or passive standby (red led), cant remember. It sure wasnt hard switched off and it was plugged in. When i pulled the RCA cable on AVR side there was a "pop" from the sub, not too loud but enough to startle me a bit. Sub volume was at ~45% on the dial.

Any help before i take the sub to service would be apreciated. I understand the hiss (rumble) is most likely down to electrical grid not being pristine but i didnt notice it before, neither have i noticed the dips/spikes, could it all be connected? Did i fry something with that cable fumble? There were no changes on electrical side of things, no breakers changed, outlets, etc.

TL;DR Sub fluctuates a lot during test tones, has a slight hiss even without signal cable that isnt influenced by the volume knob. Otherwise works "fine".
 
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bodhi

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I see the same effect in Audyssey lvl check screen, if you have the MultEQ windows app you can make it so it smooths the graph, but why. :) I also had that kind of hum, got rid of it by switching "ground lift" ON (different subs though).

I'm not a betting man but if I were, I'd wager that you just got into your head that something is wrong and then you start paying attention to little things that didn't really bother you before.

Happens to me, just recently I bumped my AVR so that one feet fell out of shelf and the box loudly dropped couple cm. Lo and behold, I heard a HUM that could not have been there before! Because I would have heard it, right? I must have broken it.

Then I forgot about it for a week and rechecked, yeah, still there when the room is silent and I put my ear right next to the amp. So, 99% it was there before and I didn't care at all.
 

sarumbear

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TL;DR Sub fluctuates a lot during test tones, has a slight hiss even without signal cable that isnt influenced by the volume knob. Otherwise works "fine".
If you feed in a fixed level tone and SPL of the sub fluctuates. You have a faulty unit.
 
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connta

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I see the same effect in Audyssey lvl check screen, if you have the MultEQ windows app you can make it so it smooths the graph, but why. :) I also had that kind of hum, got rid of it by switching "ground lift" ON (different subs though).

I'm not a betting man but if I were, I'd wager that you just got into your head that something is wrong and then you start paying attention to little things that didn't really bother you before.

Happens to me, just recently I bumped my AVR so that one feet fell out of shelf and the box loudly dropped couple cm. Lo and behold, I heard a HUM that could not have been there before! Because I would have heard it, right? I must have broken it.

Then I forgot about it for a week and rechecked, yeah, still there when the room is silent and I put my ear right next to the amp. So, 99% it was there before and I didn't care at all.
Well, i could swear the sub didnt fluctuate more than 3 dB when i first got it and ran some calibrations but maybe i just used slow time weightening on the SPL meter and remember that, that way it stays ~3dB fluctuation. Also its unbelievable to me i didnt notice the hum before but then again it is only audible with your head in the sub and even then, only dead center, bit on the side and its gone. Also, yes, this could all be in my head, it has happened before. :D

If you feed in a fixed level tone and SPL of the sub fluctuates. You have a faulty unit.
Thats why im here, thats why im asking, i'd concur with that statement. But im puzzled as to how that defect doesnt show anywhere? Shouldnt i be getting some anomalies in regular content? I use that lady gaga song "heal me" to tune the bass by ear, it has some deep bass and its constant, i'd expect that a random bass thump should be boomy at some point but i listened the song few times in a row, all good.
 

sarumbear

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Well, i could swear the sub didnt fluctuate more than 3 dB when i first got it and ran some calibrations but maybe i just used slow time weightening on the SPL meter and remember that, that way it stays ~3dB fluctuation. Also its unbelievable to me i didnt notice the hum before but then again it is only audible with your head in the sub and even then, only dead center, bit on the side and its gone. Also, yes, this could all be in my head, it has happened before. :D


Thats why im here, thats why im asking, i'd concur with that statement. But im puzzled as to how that defect doesnt show anywhere? Shouldnt i be getting some anomalies in regular content? I use that lady gaga song "heal me" to tune the bass by ear, it has some deep bass and its constant, i'd expect that a random bass thump should be boomy at some point but i listened the song few times in a row, all good.
Are we using the word “fluctuate” the same way? I meant, when sending a fixed frequency and level signal to the sub, does the SPL output of the sub changes? If it does there’s a fault with it.
 

HarmonicTHD

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Recently i switched AVRs, went from Onkyo 646 to Denon x4700h, the results are mixed considering the price of Denon but oh well, life goes on.

In any case, everything was "fine" with Onkyo, didnt really notice anything out of the ordinary. Switched to Denon and when running Audyssey i noticed that the sub level was fluctuating kinda a lot (dont remember it being this way before). Onkyo is in service for 8 years, sub 2.5, and i tinkered a lot, my memory on how things were might not be correct.

So, the problem, on Audyssey SW lvl matching screen lets say the measurement is "centered" around 75 dB it will constantly jump up and down in a span of about 5 dB (72-77 constantly) and then it would go even further at times going down to 70 then back to 80. No clear pattern is observed but it looks like it does a big spike after a dip. It really isnt constant enough to draw conclusions. The spikes are easily felt next to being measured, the windows rattle just a bit when it happens.

Tried different cable, SW2 output on Denon, checked electrical socket with a checker, reports good ground and everything, ran SW signal from REW (thru Denon), unpacked old Onkyo and tried its level signal on SW. It is about the same, it fluctuates kinda a lot. I dont remember it being this way, sure sub will fluctuate the most during test signals but i remember it being around 1 dB for speakers and 3 dB for sub, dont remember sub dipping and spiking +- 10 dB. Watched some calibration process videos online and their subs are more in line with 3 dB fluctuation, didnt see any major spikes like mine.

Then i proceeded to do a near field measurement on the sub trying to avoid the room as much as possible and thats wheen i noticed theres a very slight hiss (rumble more exact) coming from the sub. Its doing so even without a signal cable plugged in. The rumble is present as long as the sub is active (its a SVS PB1000, it has standby) no matter the signal cable, when it hits standby the rumble stops. It is very low, i never noticed it before, you really have to put your ear to the cloth grille, 1 ft away and i cant hear it. Dont remember ever hearing it in 2.5 years with the sub. It doesnt react on volume at the back of the sub, cranked all the way up or down, the rumble stays the same level. The auto standby engages as expected, it isnt influenced by the rumble.

In normal conditions, music, movies, games, i dont really see an issue. Theres a slight out of place LFE explosion from time to time but that seems to be down to the rips/masters since they are reproducible exactly every time. When i hear something like that i rewind the scene couple of times to see if its constant and it always is.

Objectively, i cannot say when the "issue" started, it really isnt apparent in real content. Im not sure if the rumble (hiss) is connected to the spikes and dips during calibration or was it there since forever just not noticed. I do know that i did fumble a bit when changing AVR, i didnt turn off the sub on the hard switch before unplugging the signal cable on AVR side. AVR was on standby (electricity plugged in, video passthru not enabled, no ARC, CEC or anything, red LED). The sub was also plugged in but it might have been on active standby (blue led) or passive standby (red led), cant remember. It sure wasnt hard switched off and it was plugged in. When i pulled the RCA cable on AVR side there was a "pop" from the sub, not too loud but enough to startle me a bit. Sub volume was at ~45% on the dial.

Any help before i take the sub to service would be apreciated. I understand the hiss (rumble) is most likely down to electrical grid not being pristine but i didnt notice it before, neither have i noticed the dips/spikes, could it all be connected? Did i fry something with that cable fumble? There were no changes on electrical side of things, no breakers changed, outlets, etc.

TL;DR Sub fluctuates a lot during test tones, has a slight hiss even without signal cable that isnt influenced by the volume knob. Otherwise works "fine".
The fluctuation is normal on the MultiEQX screen. Don’t worry. Mine does the same, the results are fine and I confirmed the then many times over with REW.

I presume it is the pink noise signal causing the fluctuations, but I am not 100 percent sure.
 
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connta

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Are we using the word “fluctuate” the same way? I meant, when sending a fixed frequency and level signal to the sub, does the SPL output of the sub changes? If it does there’s a fault with it.
I'll check with pure sine waves, only checked with sub cal noise. Yes, it fluctuated a lot, so much so that a clear green box was unatainable with Audyssey SW level matching.
 

LTig

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Then i proceeded to do a near field measurement on the sub trying to avoid the room as much as possible and thats wheen i noticed theres a very slight hiss (rumble more exact) coming from the sub. Its doing so even without a signal cable plugged in. The rumble is present as long as the sub is active (its a SVS PB1000, it has standby) no matter the signal cable, when it hits standby the rumble stops. It is very low, i never noticed it before, you really have to put your ear to the cloth grille, 1 ft away and i cant hear it.
Do you still hear this rumble ehen you disconnect the sub from the AVP (only mains connected)? If yes the sub is faulty, if not you might have a ground problem.
 
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connta

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Ok, update, the sub is fine most likely. Pulled it out in the middle of the room, its steady as ever, like +-1dB. Back to old position, it fluctuates like before.

Tried a sine wave at the original position first, different frequencies fluctuated differently so that was an indicator it is the room after all. Since the room is pretty big, dead center should be close to free field measurement and it was. I'll have to rearrange some stuff and rework the room, its overdue i guess.

Gonna go to my local SVS dealer today to see if there is any hum on their showroom units. The hum doesnt sound that concerning, it is totally possible i just didnt notice it. My MLP is around 4m from the sub, there is no humanly way you can hear it there.
 

MCH

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Hi @connta

The rumble you are describing is exactly my experience with my two SVS SB1000 subs. The rumble is there whenever the sub is on, be it connected to a source or not and independently of the volume. The only setting that reduces it is the crossover frequency: the rumble gets lower when you reduce the xover frequency with the knob on the back.

I initially bought one SB1000 and thought it was faulty. I made a video and SVS kindly sent me a replacement amp plate, as according to them the plate might be faulty, and the rumble with the new plate was less (subjective impression) but still there. Then I bought a second SB1000 and it has exactly the same issue. This makes me pretty confident that it is not 3 faulty amp plates but something common to the product. What I find surprising is that before yours, I could not find any other reports on the issue. Note that subjectively the loudness of the rumble is different with the 3 different amp plates

May I ask you to try to play with the xover knob and see how it affects the rumble? Also, may I ask you as well to please post a solution if you ever find one? I find the rumble very annoying specially at night when watching films with relatively low volume…

Thanks!

More insight here:

 
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connta

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Hi @connta

The rumble you are describing is exactly my experience with my two SVS SB1000 subs. The rumble is there whenever the sub is on, be it connected to a source or not and independently of the volume. The only setting that reduces it is the crossover frequency: the rumble gets lower when you reduce the xover frequency with the knob on the back.

I initially bought one SB1000 and thought it was faulty. I made a video and SVS kindly sent me a replacement amp plate, as according to them the plate might be faulty, and the rumble with the new plate was less (subjective impression) but still there. Then I bought a second SB1000 and it has exactly the same issue. This makes me pretty confident that it is not 3 faulty amp plates but something common to the product. What I find surprising is that before yours, I could not find any other reports on the issue. Note that subjectively the loudness of the rumble is different with the 3 different amp plates

May I ask you to try to play with the xover knob and see how it affects the rumble? Also, may I ask you as well to please post a solution if you ever find one? I find the rumble very disturbing specially at night when watching films with relatively low volume…

Thanks!

More insight here:

Hello MarcosCh i have stumbled onto your thread in the search prior to posting mine and yes, the xover knob is the only thing actually influencing the said hum like you described. If i set it to 80Hz the hum is gone on my unit. I figured that out immediately just didnt write about it since it was already a WoT and i also forgot. :)

I dont think there is a solution, probably a unit to unit variance. It took me 2.5 years to notice mine is doing it, without deliberately listening for it (and with a sick noise floor) i can hear it but in normal situations, no way. I suspect it is down to electrical grid. I live in a huge 3 apartment house, electrical installation isnt the greatest, had a problem with HDMI losing connection on any resolution above 4k60hz 4:4:4 and only one cable type that i bought out of at least a dozen works, they all work at my friends house. :/ I only figured that one out because i noticed that a light switch on another floor than mine is tripping a HDMI handshake loss yet with set of two "select" cables it now does 4k120hz 4:4:4 passthru without a problem (with all other cables even direct connection is flaky, passthru you can forget about). What compensates for what exactly in that situation, i got no clue. I also suspect these electrical problems are down to not every outlet and light is connected the same way. On EU grid, "it doesnt matter" what orentation you connect null and phase, for 98% of uses. But those 2% are sensitive things like computers, TV, AVR's, high output HDMI, etc. In other words, stuff that can give you nightmare problems. :D I dunno any more rly...

When were your subs purchased? Im also based in EU, maybe we can track em to a "not so great" batch. Im gonna make a trip to local SVS dealer see if there is a similar situation on their showroom pieces, will post results.
 
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MCH

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Hello MarcosCh i have stumbled onto your thread in the search prior to posting mine and yes, the xover knob is the only thing actually influencing the said hum like you described. If i set it to 80Hz the hum is gone on my unit. I figured that out immediately just didnt write about it since it was already a WoT and i also forgot. :)

I dont think there is a solution, probably a unit to unit variance. It took me 2.5 years to notice mine is doing it, without deliberately listening for it (and with a sick noise floor) i can hear it but in normal situations, no way. I suspect it is down to electrical grid. I live in a huge 3 apartment house, electrical installation isnt the greatest, had a problem with HDMI losing connection on any resolution above 4k60hz 4:4:4 and only one cable type that i bought out of at least a dozen works, they all work at my friends house. :/ I only figured that one out because i noticed that a light switch on another floor than mine is tripping a HDMI handshake loss yet with set of two "select" cables it now does 4k120hz 4:4:4 passthru without a problem (with all other cables even direct connection is flaky, passthru you can forget about). What compensates for what exactly in that situation, i got no clue. I also suspect these electrical problems are down to not every outlet and light is connected the same way. On EU grid, "it doesnt matter" what orentation you connect null and phase, for 98% of uses. But those 2% are sensitive things like computers, TV, AVR's, high output HDMI, etc. In other words, stuff that can give you nightmare problems. :D I dunno any more rly...

When were your subs purchased? Im also based in EU, maybe we can track em to a "not so great" batch. Im gonna make a trip to local SVS dealer see if there is a similar situation on their showroom pieces, will post results.
Thanks for the feedback. Mine were purchased ca. one year ago.
Hm, i don't know if it is related to the quality of the electricity supply/installation or not, but i have other audio devices plugged to the same and other outlets and they all are dead silent. If the svs is extremely sensitive to those things i blame it to svs design not the electricians job.
Well, anyways, i keep the two subs with the low pass set so i cannot hear the rumble from the listening position and don't think much about it, but i find it a shame... A project i have on the list for when I run out of projects is to leave the amp plate in place but feed the subs with an external amp to see if it goes away, but at the moment i don't have a spare amp to test it.... btw, if someone can recommend a cheap, ideally balanced, amp for this task...
Thanks again!
 
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connta

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No problem, thats why we're here.

Also no "bad batch" im afraid, mine was purchased 2.5 yrs ago, so i guess its safe to say it is due to the design. It is probably very sensitive to electrical wiring or you have a very bad setup in that regard, any other electrical problems? Do you possibly get HDMI video cutouts on your devices, are you using HDMI 2.1 as 4k120 or 8k60 possibly?
 
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connta

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Ok, "bad news", went to the dealer and showroom models also have a hum and they even have voltage regulator on their power line. The silver lining, my hum seems to be even less than theirs, ha! No wonder i didnt even notice it in 2.5 years, a normal user (one who plug'n'play) would probably tell me im crazy if i told him theres a hum. It really isnt audible until your ear is next to the grille.

Well, tbh im kinda used to NOTHING living up to expectations any more. I mean you cant even buy a single HDMI cable and be sure it works in every situation, always. I have like 30yr old SCART's that are well and alive today. Got at least 5-6 brand new HDMI's that are finicky, one works on LG tv but not on Samsung, one cuts out, other has horizontal lines...
 

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It really isnt audible until your ear is next to the grille.
such_a_shame.jpg

I said it before, i say it again, we suffer more in imagination than reality. ;)
 
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connta

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Im necroing my own thread to update, the sub "croaked" some 6 months after i wrote this, the hum increased gradually until it was totally audible at all times. Took it to a repair center and even tho my country/dealer only abides by the EU warranty of 2 years the good people of SVS accepted the unit for repair under warranty. Shout out to them and a rep whos name i think was Dave, guy answered a support call on a sunday, i mean how often do you see that?
 

MCH

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Im necroing my own thread to update, the sub "croaked" some 6 months after i wrote this, the hum increased gradually until it was totally audible at all times. Took it to a repair center and even tho my country/dealer only abides by the EU warranty of 2 years the good people of SVS accepted the unit for repair under warranty. Shout out to them and a rep whos name i think was Dave, guy answered a support call on a sunday, i mean how often do you see that?
Sorry to hear that. I hope they can repair them. I ended up using the two i have as passive with an external amp. I am very satisfied with the result and i don't have any noise whatsoever anymore:

 
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connta

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It has been handled, the sub is back and working like before. There is still a hum when you put your ear to the grille but as i already confirmed back then thats "by design", the showroom models have it also. Tho since it took me 2.5 years to actually notice it, meh, it is what it is. Truth be told my sound floor is sick, under 20 dB, so i hear everything. Had a woodworm eating my furniture recently, i heard him munching and took him out, yet this hum cannot be heard if youre right in front of the sub standing up, it is that low. You gotta crawl down and put your ear to the grille to hear it. For all intents and purposes it is a non issue if it stays on this level.

Ill have to check out that mod of yours in detail when time permits, i might even copy it down the line!
 
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