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May 11, 2020

Re: What could cause audio drop? L1 MII/B2 with T1

Hi ajb,

quote:
Originally posted by ajb:
Same exact issue here on the 4th of July. Both Model II / B2 dropped for a few seconds, came back on. This happened five times, with a T1 in play. Played another gig that night, minus the T1, not a single problem. Played a wedding last weekend with the T1, and the Model IIs on different circuits. Same problem with dropouts. So my T1 is now in the hands of Bose repair. More to come, I'm sure...


Please let us know how this turns out.

Thanks.

ST
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Apr 16, 2015

Re: What could cause audio drop? L1 MII/B2 with T1

I read the power considerations page yesterday. There are no specifics. I read that each T-1 Model-2 requires 6 amps, is this correct? Where are the specs regarding sufficient power supply ratings ?
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Re: What could cause audio drop? L1 MII/B2 with T1

Hi partydjz,

I am very sorry that you and others are experience audio dropouts. We definitely understand that your equipment has to be absolutely rock solid.

The user manual states 5 amps or greater, so six amps is a good approximation. For that reason, we recommend only up to two L1 MII’s on a single 15A circuit breaker in the US.


A quick review of three POSSIBLE causes of audio cutting out follows. That will help us determine what is going on.

1. If there is a non-Bose B1/B2 cable, OR if the B1/B2 cable has a defective, loose connection, audio can intermittently mute. It may happen with loud music because the speaker will be vibrating and shake the loose connection. This will sound like a clean muting of all audio for a second or so. There will be no visual indication.
Fixable by tightening the screws in the connector.

This would only happen on one L1 MII at a time. If two dropped out, this is not the issue.



2. Very low, out-of spec, AC power (less than ~105 VAC on a 120V system, or less than around ~215 V on a 230 V system. The manual states 110 and 220 for good measure) coupled with high signal level. This can be caused by a low power source, or one where the outlets are a very long distance from the electrical panel, extra equipment on the same electrical branch, power sags or dropouts, long or multiple extension cords, or small gauge extension cords.

In this case loud music increases the current draw, and the voltage drop over the extension cord will lower the voltage enough to cause a reset of the T1, or the L1 MII base.

If the T1 resets, the LED’s (input trim level, mute LEDs) will turn off. The LCD display will remain blue, but be blank until the unit restarts.
The L1 MII base can reset but it does not show on the indicators.

In either case the answer is to ensure the power supply is solid, and dedicated to the audio equipment, and to have as short cords as possible with large wires.
Also be aware that separate wall outlets may still be on the same breaker.

If there are intermittent voltage sags or outages in your area (as there are in parts of Florida, for example), it is possible that some equipment that does not use a lot of power (like mixers) will continue to operate, and equipment requiring high power, like amplifiers, may not be able to produce audio.

Those outages can happen any time, but are less likely to repeat, or unlikely to happen only at loud parts of the music.



3. Defective units: If the first two are not the cause, then either the T1 or base unit may be defective, and you should contact customer service.


I hope this helps.

Bill-at-Bose
(edited to add signature)
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Re: What could cause audio drop? L1 MII/B2 with T1

Hello Bill,

I had a very similar experience in mid June.

During sound check, I was preparing to set the gain for a fellow musician's acoustic Takamine guitar that has a factory pickup with preamp (possibly Fishman). Not realizing that his volume control was almost at maximum he played a solid strum which caused the T1 and L1 Model II to momentarily shut down.

As I turned my attention to the T1, the display back-light was on but the LCD was completely blank. I believe that the power indicator on the power stand was red momentarily but I'm not certain on this point. I'm also not sure if the T1's back light momentarily turned off or not.

After the system reset itself, and, with the guitar volume control turned down, there were no other issues and the rehearsal proceeded without any other incidents. There were no issues during the concert the next day and I have used this system at least a dozen times since without any issues.

My systems are always connected to an older Furman AR-1215 voltage regulator and there were no other devices sharing this AC circuit. The room is a small rehearsal space in the theatre department of a local university; I have never experienced any power issues in any of their facilities. I strongly believe that this momentary shut down was directly related to the extreme output level of the guitar preamp.

Lastly, I have no desire to attempt to reproduce this event as a test but if you would like to test this out in your lab I would recommend a very strong signal with a very fast attack.
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Re: What could cause audio drop? L1 MII/B2 with T1

Hi, Mark,

Thanks very much for the information.

Bill
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Jul 13, 2009

Re: What could cause audio drop? L1 MII/B2 with T1

Well, I'm not feeling any better.

I received my T1 back from Bose Repair while I was on vacation. I just got off the phone with Bose (after a 35 minute hold) and found out that they cannot answer my simple question: Was something wrong with the unit?

I need that answer. If something was wrong, and it was repaired, then I know where the fault was, and I can confidently re-introduce the T1 to my setup. However, if nothing was wrong, then that means the problem exists elsewhere in my system, and I have NO ideas. All I know is that the issue happened with the T1 and did not happen without it.

I find it hard to believe that a company cannot answer that simple question: What was wrong, and how was it fixed?

I am very disappointed in this experience, and it will make me rethink the decision to use the T1.
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Apr 2, 2015

Re: What could cause audio drop? L1 MII/B2 with T1

I've reached out in a private message to see if I can find any additional details.
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Jul 13, 2009

Re: What could cause audio drop? L1 MII/B2 with T1

It's official. I am DONE with the T1 Tone Match. I sent it back to Bose for repair, they did something to it (but refuse to tell me what) and it's been fine for the month since I got it back. But two dropouts at last night's wedding have made my decision for me. I'm almost to the point of not being a Bose DJ anymore, that's how fed up I am.

So, anyone want a recently refurbished, slightly used T1 ToneMatch?
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Feb 13, 2017

Re: What could cause audio drop? L1 MII/B2 with T1

This won't be short. The hypothesis is that there's a low line voltage condition that is occurring. When you are using a ToneMatch connection to the L1M2, the T1 gets it's power from a dedicated power supply from inside the L1. Now, the L1 is quite tolerant of low line voltage conditions, but we believe the T1 to be more sensitive and could cause the T1 to reboot itself. So, we need to define a low voltage condition. The L1 requires a minimum voltage on the line. There are some scenarios that could cause low voltage conditions - bad venue power, other (unseen) devices on the circuit, long extension cords, bad power connections, could introduce an resistive load on the AC line, causing the voltage to sag. Sag=bad. It doesn't appear at first glance that Andy is using inferior techniques, in fact he's a seasoned DJ like our buddy Cap. To fix the immediate issue, Andy is going to try running the external T1 power supply and use a TRS Y-Cable and feed his two L1M2s using the Master Output on the T1 (not using the Tonematch port). As well, there's a good chance that the some popular line conditioners Andy is using between the L1s and the AC outlet could be causing some trouble. In general, we recommend a direct connection between the L1s and the AC mains. Depending on how curious Andy is about the causality, we should find out which of the two paths were the culprit... or I could be wrong on both accounts!
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May 24, 2011

Re: What could cause audio drop? L1 MII/B2 with T1

ya, the T1 is not the issue.

I would recommend running the T1 with hard power and using a custom cable 1/4 TRS to split (dual) 1/4 TRS to each of the L1s. Thais what I do.

I will say that from previous experience, the L1 does not do well with low voltage, regardless of what people say or the specs say.

Low voltage can be bad power from a venue or using low gauge extension cables or too long of runs.

I hope this helps. I had a similar issues a coupe years back and even once this year. All of was related to low voltage.

Go buy a Kill O watt. It will help out out as you can "read" the power.