White noise issue with PAS

Ed here with a question for anyone who can answer it. I have had the system for about a week and really like it but for the amount of noise it makes when the master control on the remote is at 12:00 or more. Keep in mind this is without anything hooked up to it yet, just the operating noise of the amps I guess.
It is not offensive at clubs or coffee houses but I do host very intimate home concerts with captive audiences and very quiet musical passages played by musicians (I wont name names)
but trust me they are used to the best.
I think the noise would be a problem at these shows.
I am well aware of gain staging and the best way to acheive the cleanest signal but I hope there may be one of you with a trick I don't know to make this noise less of a problem. Perhaps that is just the way this system is - honestly though when I think Bose I think audiophile quality and this certainly isn't. I also know it is meant for live sound where this type of noise is common in other systems but for 2k...... you get the point. I would have shelled out a little more to have a quiter system. Any thoughts?

Thanks.
Original Post
Hey Ed,

I've heard of similar issues once or twice before, where the system has a lot of hiss by itself. I don't recall exactly what the "fix" was but I do believe that it was a manufacturer's defect and swapping out the Power Stand fixed it.

I'd like to ask you to call our tech support team at 877-335-2673 and tell them what's happening. I think they are going to recommend swapping out your Power Stand for a new one.

There should not be a lot of hiss at the 12:00 position unless your Power Stand is set up next to something noisy and it's bleeding noise into the inputs (like a TV or PC monitor). This does not sound like your situation at all. Am I right?

Steve
You are correct sir. Is the system supposed to be close to dead quiet at 12Red Faceo? Just wondering because the hiss I have is not enough for me to return it if it will only be slightly better or not better at all.
Can anyone at your place who owns one attest to that? If so I will return it and be happier with the replacement. If not i'll still keep it. DId a show with it last night and it was great. Thanks.
Hi Edpas,

I recently did some "testing" listening for hiss.

quote:
Originally posted by ST:
Hi Michael,

I read your post and wandered off to the other room and fired up my System.

I *can* hear a hiss with
- no inputs
- trims off
- Channel Levels on Remote at 0
- Master Volume 1/2 to 3/4 to 12+

It is not very loud. With
- the Master Volume at 1/2 way,
- in a room about 35' x 40'

Within 4 feet I am aware of the hiss

Standing 8 feet away it blends into background noise (although that room is pretty quiet).

Looking at this another way.
- In a live music situation I probably wouldn't notice it.
- If the System is in a playing situation, I doubt you would hear it in the audience.
- If I was playing, or playing background music with the trims set normally and the Levels and Master at 12 1/2 way - at 8 feet away, I wouldn't notice.

That last three conditions describe how I run my System most of the time. The hiss is so far in the background I just don't notice. That's why I had to go and actually listen for it. Tried it with two different Systems - pretty much the same results for both.

Now, I can hear it and am aware of it if I'm within 4 feet and I listen for it. But I would also not be standing with my ears that close to the L1 with all the settings up that high if I was actually playing. Well in tight quarters maybe half-way, but certainly no higher.

If it seems louder to you than what I've tried to describe, can you talk more about the setting in which you are hearing it?


In context: Hiss with no inputs
I haven't mentioned this before, but I have had more hiss on powerup a few times. I think it must have something to do with the initialization of the software when it first powers up, because if I cycle the power (turn it off, wait a few seconds, & then power back up) the hiss is gone. Just my two cents.
Hey guys, and thanks for joining in the discussion.

The hiss of which I speak I suspect is just amp noise of some kind - it's just like my old JBL and power amp rig where when it was on you could hear a hiss coming from the speaker cab. I have only had the system for a few days and fortunately I have had time to play with it and have found that the master on the remote is ultra sensitive. Slight changes in setting have a huge affect on how the system sounds and you have to go easy with it.
I found an acceptable sweet spot where the volume i'll need for my intimate home concerts yields very little noise.(some but not awful).

I have always listened for noise because of an epiphany I had at a music store when I was 15 years old. I was playing electric guitar and used the standard MXR(and other) stomps of the era and was just used to alot of noise. Then the owner showed me the T.C Electronics (new company at the time) Chorus/Flanger pedal. 225.00 in 1981!! I plugged in the Strat to it and to my amazement no noise came from the amp until I actually played something!!! It changed my view of things. So when I buy something expensive ( I did shell out for the T.C in '81 qand still use it to this day) I am listening to hear nothing and when I do hear something it bums me out a little.
I suppose it would cost a lot more money to manufacture a totally noise free system that can cover 300 person venues.
I realise that this is not a home stereo system.


Thanks for your input. I will aspire to learn all I can about this very cool system. I put a bass through it yesterday and it sounded fantastic. Lots of territory to cover here and I am looking forward to it. Thanks again!
I'm also getting a hiss with no inputs. I have a factory refurbished unit (2 months old), and I could be imagining it, but I believe its hissing more than when I got it a couple months ago.

Until today, I hadn't ever plugged the remote. I am a laptop musician, so I only use channels 3 and 4.

Again, the hiss came with nothing plugged in (except the power cord) and was the same volume no matter what levels I turned channels 1 through 4. It's loud enough that I could hear it 10+ feet away in a fairly quiet room.

So I plugged in the remote and voila! The Master volume level and the hiss volume were directly proportional.

Now up to about 9 or 10 o'clock on the master volume I hear this "only when your ear is pressed up to the unit" hiss. Above 9 or 10 o'clock (and all the way up to Max volume) the hiss increases along with the gain. The hiss still has no correlation to the gain setting on the individual channels, only the master.

I'm not currently performing, but if this is a defect (and I think it probably is) I'd like to get it looked at while my unit is still in-warranty. Not sure if it's a PS1 or an L1 problem (pretty sure it has nothing to do with the bass unit!). Also not terribly thrilled with the thought of having the unit gone for weeks on end...

-mike
Hey Mike,

My gut feeling is that this hiss is a relative issue. Some players are going to accept it for what it is and some will not and perhaps return their units to Bose for a refund.

I'm sure that in the design phase of this the Bose engineers knew about the hiss and made a decision as to what an acceptable level would be given that this is a live sound rig. (correct me if i'm wrong Bose guys).The system was not marketed as a dead quiet amplification source but as I said in an earlier post, we may have expected that from a product with the Bose name on it and at the price point they placed it at.

If a re-design of the system based on customer feedback were ever implemented I would strongly reccomend that they address the hiss issue and either reduce or eliminate it somehow. (Please guys- not with a noise gate!!!) I believe that for most end users who bought the PAS for use as a P.A. the hiss would not really be an issue.

Careful gain staging with outboard gear (i.e. laptop,mini mixer,etc..) will help reduce inherent system noise but if it's got amps in it the noise will always be there. I suppose the Bose folks had to ask the question at some point if customers would shell out say an extra 500.00 bucks for a system with quieter more refined amps and decided that this design was the way to go. Pure speculation, but food for thought.

Best to all,Ed.
Hi Ed,

Thanks for your response. My issue isn't with the very small hiss that's there at very low master volume settings. My issue is with the hiss at master volume settings above 9:00 - it's louder than posts from -at-Bose guys have indicated it should be and seems (subjectively) to be getting worse.
quote:
... My issue isn't with the very small hiss that's there at very low master volume settings. My issue is with the hiss at master volume settings above 9:00 - it's louder than posts from -at-Bose guys have indicated it should be and seems (subjectively) to be getting worse.


I'm having the same problem that Mikeymike described in Jan., '06. A hiss has always been detectable, but this week in the little restaurant where I work, wait staff said it was especially noticeable and annoying. I tried to compensate by setting the L1 Power Stand volume to a little over 10 and the channel gains on the mixer to 2:00 with the master at 9:00. This reduced the hiss to a more bearable level but still more noticeable than in the past. I had the same results when I replaced the mixer with the Remote, plugging directly into channels 1 & 2. I tried swapping out instruments and several other suggestions that I read here on the forum. The only constant was the use of condenser pick-up mics in the instruments. I may have not gotten the gain staging stuff quite right. I have never been able to get a steady green light with the occasional flicker of red on the Power Stand trim light as has been suggested. When I use the mini mixer rather than the Remote, I go from the Main Mix Out - Right to channel 1 of the power stand and Left to channel 2 – I don’t know if this has any bearing since I had the same noise when I used the Remote and plugged directly into channels 1 & 2. I would appreciate any advice.
Ciao,
Jerry
Improper gain staging will ABSOLUTELY create more noise. There are some microphones that I have had the initial gain turned ALL THE WAY UP. Are you turning the phantom power on for a condensor? Seems like a dumb question, but I don't know everyone's knowledge or skill level and I run across people every day who have no idea what phantom power is for. If you're still not getting a strong enough signal, you might want to try some different cables or a different mic.

To give you an idea of the noise factor, I was at an establishment last night with piped in music. There was this buzz happening loudly thorugh their speakers. I asked what the music source was and they said a computer. I asked how often they had the buzz and they said "a lot lately". So I went back to their workstation, turned down the master volume of the sound system and turned up their computer volume. Music was just as loud, no buzz.

When I go into a store and the crew says "our acoustic room's system just makes so much noise" I know exactly what to do. So I show them how to set the gain properly and then, whatdya know, the hiss goes WAY down. I won't say away, because any system is going to have electrical noise in it and an amplifier/speaker combination just amplifies whatever it gets. But you can reduce the noise floor with a stronger input signal.
I have had an issue with hiss on more than one of my L1's forever. but it's intermittent. Sometimes just a quick power cycle (turn off, wait 15 seconds, turn back on) will reset the computer in the powerstand & clean up the hiss.

Worth a try if it only seems to happen sometimes.
Thanks everyone for responding. I’ve been using the Bose L1 with a B1 since 2003 with pretty much the same rig. I’ve never had the noise I’m getting now. Somewhere along the line I think that I lost whatever ‘gain staging’ I had set and I don’t remember how I got it to the acceptable level. However, I could be way off base.
Maybe, if I describe my equipment someone will come up with an “aha, I see what the problem is …” My normal set-up is a midi accordion with the Limex Pro Mic system (using preset 55 made no difference). This consists of 14 mini condenser mics (10 treble, 3 bass and 1 vocal). I usually run the accordion and a module or arranger keyboard through a mini mixer (to get some reverb). From the Mixer to the L1- I described in my initial post. I did swap out my regular cables with Monster cables, bypassed the mixer and went directly into the L1, and just about every other suggestion that I read on the forum Except – change the mics. That’s something that I’ll have to keep constant.
Let me add here that I just unplugged the accordion mics from the L1, and the noise dissipated. So, at this point it looks like it’s the mics – incidentally, the noise didn’t change with the phantom on or off or with the mic gains turned down to zero on the accordion.
It would seem that I need a lesson on gain staging - on an elementary level.
Ciao,
Jerry
10 treble mics. Hmmmm. Try turning down the HIGHS. Almost all electrical components have some level of self noise. Sometimes things get noisier with age. Dirt and moisture could also cause noise.

If you are lucky it will be a simple problem of too much boost of the highs, and a slight cut will "fix" it.

Clean all connections with contact cleaner.

O
Yesterday I set up for my evening gig. My rig is just vocal, Variax, and Porch Board. At power up I was hearing a low volume hiss from my L1. It was so quiet as to be pretty much undetectable a few feet in front of the stage. Long story short, I had inadvertently turned on the unneeded phantom power on channel 1. I pushed the button, and the sound is clean again. I just wanted this post to warn others of that possibility if you hear a hiss.
Respect
Andy
ed,
I have gone many rounds with tech support about this issue. The noise is indeed inherent to the system. In bars, hardly noticable. In concert, annoying.

Are you using MI or MII? I own the MI's and have always noticed a high-frequency rise on-axis and a drop off-axis. Every Bose tech support phone answerer responded with "hardly noticeable", yet the company was compelled to create an entirely new version of the MA12 (L1) to correct this. Hardly noticeable?

These types of interactions have been a source of frustration for me in dealing with Bose. A similar situation related to the quality of the B1 cable supplied with the system was finally resolved by the individual who makes aftermarket B1 cables. These cables need to be wired very specifically to avoid interference with the sensing technology over longer runs. No one at Bose has been willing to discuss this with me.

I returned a B1 because it was making noise and simply wanted to know what was wrong with it: no response. They replaced it: much appreciated, but why the secrecy?

I have really enjoyed my Bose products. I have not enjoyed the politics involved with the sharing of information. Bose does a huge disservice to its products, its employees and its customers by allowing this "we know better" attitude to cast a shadow over its accomplishments.
quote:
Originally posted by Sarkis:

Are you using MI or MII? I own the MI's and have always noticed a high-frequency rise on-axis and a drop off-axis. Every Bose tech support phone answerer responded with "hardly noticeable", yet the company was compelled to create an entirely new version of the MA12 (L1) to correct this. Hardly noticeable?

Sarkis, Yes, there is definitely some rise in the high frequencies on axis with the L1 Model I. For you, a discerning listener, it is clearly more than "hardly noticeable".
My guess is that our tech support and sales team was trying to present as balanced a view as they can. (I'm in engineering, not tech support, so I can't speak for them directly).

For the majority of folks who use the L1, the system is such an incredible improvement in dispersion pattern on the live stage that it just blew away the systems they had used before, and characteristics like you describe are viewed as a small part of the big picture.
I guess I'm agreeing with you that it is not possible to tell someone that an audio characteristic will be "barely noticeable" or even "incredibly obvious" to them, since the listener will make that judgement for themselves, based on their own skills and priorities.
Perhaps if they had said that "most users" find it barely noticeable, it would not have felt to you like they were trying to deny what your ears told you was true.
quote:
These types of interactions have been a source of frustration for me in dealing with Bose. A similar situation related to the quality of the B1 cable supplied with the system was finally resolved by the individual who makes aftermarket B1 cables. These cables need to be wired very specifically to avoid interference with the sensing technology over longer runs. No one at Bose has been willing to discuss this with me.

I'm happy to discuss this (although I know it's late). It's possible that you experienced a slight time delay between our engineering work and the information that got to tech support.

Here's what happened: We had received complaints of L1 sound dropping out intermittently, and as you can find on the forum (no secrets here!), we had a problem with the screws coming loose in the B1 cables, and immediately implemented strict manufacturing changes to fix the issue. I haven't searched, but I believe people have not had this problem any more with recent B1 cables.

When the issue with longer B1 cables came up, our first thought was that it could be the same loose connection problem.
If I remember right, Mark from Audiopile (who is definitely one of our favorite people) had found that larger guage wires were less susceptible to the problem. Hilmar and I looked into it further to find the root cause, and found the rather subtle issue that, depending on the wire gauges and how the wires were paired in the cable, loud bass signals (in the speaker pair of wires) in extra long cables could capacitively couple into the sensing pair of wires. When it happened, the L1 "thought" you were changing your B1 configuration and would mute.

So we looked at capacitance per foot with different wire guages, and with twisted vs untwisted pairs in the same cable, and looked at our sensing algorithm, and did two things to solve the problem:

We had Mark at Audiopile send us some samples to our new spec, we checked them, and they worked well. This gave a method for our customers who needed a long B1 cable to get one that worked.
The second thing we did was redesign the L1 software so that it could "filter out" the effects of momentary crosstalk and not cause the problem. That way future L1's would not have the issue.

So, with Mark's help we found and implemented two solutions to make the extra long B1 cable work, a use of the system that affects only a relatively small number of our customers.

quote:
I returned a B1 because it was making noise and simply wanted to know what was wrong with it: no response. They replaced it: much appreciated, but why the secrecy?

I don't know what you arranged with your B1. Typically our phone tech support is not set up to repair customer's units and give them a report on the failure mode. We have to send a unit right to engineering to do that. This is more an issue of logistics rather than secrecy (goodness, what would we have to hide?) Your unit may have been sent to our remanufacturing plant in South Carolina, where it gets stored with other units, then when enough are collected they get looked at and remanufactured, if appropriate. We track types and quantities of failures, so we can take corrective action on any common ones. But we don't typically track them per user.


quote:
I have really enjoyed my Bose products. I have not enjoyed the politics involved with the sharing of information. Bose does a huge disservice to its products, its employees and its customers by allowing this "we know better" attitude to cast a shadow over its accomplishments.

Bose ain't perfect, but as far as I know we try to be as open as possible on this message forum, with private posts, and with our tech support. Many of our customers, including yourself, have benefitted from community support on this forum, response from design engineers on the forum, and the offer of personal emails from the engineering team here at Bose.

We are always open to suggestions on how to improve.

Sincerely,
Bill
quote:
Originally posted by Bill-at-Bose:
The second thing we did was redesign the L1 software so that it could "filter out" the effects of momentary crosstalk and not cause the problem. That way future L1's would not have the issue.


Thanks Bill. Is the redesigned L1 software included in the preset updates, or if not, is there a way we can load it into an L1 Classic or earlier L1 MkI?

Add Reply

Likes (0)
Having trouble signing in?

We recently updated our sign-in procedure and if you have old sign-in data cached, this can create a problem. Please:

  1. Clear your browser cache and cookies
  2. Then close the browser (not just the window)
  3. Open the browser and try again
Thank you

Please make sure that your profile is up to date
×
×
×
×