Dumb hardware

Mike0001

Well-Known Member
Actually, not so dumb, more second-order dumb.

Take an AV Amp that is aware of what speakers are attached each time it switches on and sends its signal accordingly. Eg, if you don't have a subwoofer, it doesn't send a signal to the subwoofer output.

Take a subwoofer that has an intelligent sleep mode, which uses 0.1A but switches on the sub only if there is a signal to its input.

Put the two together and...

I kid you not! :mad:
 

Ezra Pound

Well-Known Member
Does the Amp. only have the auto speaker detect?, can't you tell the Amp. which outputs to turn on. I presume the Amp. only has a phono output that feeds a powered Sub, so I'm not sure why the Amp. doesn't detect the Sub even if it is in intelligent sleep mod, it would only be detecting the phono termination, that would still be in place
 
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Mike0001

Well-Known Member
Does the Amp. only have the auto speaker detect?, can't you tell the Amp. which outputs to turn on. I presume the Amp. only has a phono output that feeds a powered Sub, so I'm not sure why the Amp. doesn't detect the Sub even if it is in intelligent sleep mod, it would only be detecting the phono termination, that would still be in place


I solved the problem by turning off auto-standby on the sub and using one of those power-saver sockets with the amp as trigger and the sub as victim.

All I know is that they don't talk to one another. The amp appears to be aware of what speakers are attached and in a split second it decides there is no sub, before the sub can detect a signal and come to life. Could it be the amp detecting the impedance of what is attached? Dunno.

No, there is no way to tell the amp what is connected. When you set it up, you can tell it whether you have bi-amped the front speakers or are using high front speakers instead, but it then just knows whether rear speakers are there, a sub, etc.
 

gomezz

Well-Known Member
Why would you an amp need an auto-speaker detect anyway? How many times is the speaker config likely to change once it is first installed?

That said I have only just realised (after twelve years) that I *can* get both speaker and headphone output out of my Denon amp if I connect the headphones to the tape monitor output rather than use the headphone socket which has the annoying habit of muting the speaker output without the option.
 
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Mike0001

Well-Known Member
Why would you an amp need an auto-speaker detect anyway? How many times is the speaker config likely to change once it is first installed?

Bi-amping speakers? Adding rear surround speakers? Adding high front speakers? Speaker wires coming loose?

I guess the idea is that you don't have to bother telling the amp what is connected because it knows. The Tannoy sub with its optional sleep mode was presumably something they had not even thought about.
 

Black Hole

May contain traces of nut
Presuming the connection is detected by the impedance on the line, I don't understand why the sub changes its impedance whether on or off. This seems to be the main problem, and could possibly be bypassed by fitting a dummy load in parallel.
 

gomezz

Well-Known Member
Bi-amping speakers? Adding rear surround speakers? Adding high front speakers? Speaker wires coming loose?
The average user is likely to only do one or all of those things once or maybe twice in the lifetime of the system. Perhaps it is a feature aimed at dealers and reviewers who I can see would benefit from it although they are just the people who should *not* need their hands holding - in theory anyway.
 
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Mike0001

Well-Known Member
Presuming the connection is detected by the impedance on the line, I don't understand why the sub changes its impedance whether on or off. This seems to be the main problem, and could possibly be bypassed by fitting a dummy load in parallel.


It's a long time since I studied electronics, but if the impedance remained the same wouldn't that mean the sub was drawing juice even when asleep? I suppose it would not be powered on, though, so that would be a saving.

I have lived with this for a few years and found the work-around I mentioned above, and the other problem is that with slow booting equipment attached to the amp, hummies and things, there is quite a delay before the amp would send any signal to the sub, so I am just guessing that the sub decides there is no signal and stays in sleep mode, the amp then decides there is no sub and doesn't send any signal to it even when the hummies have booted, so they remain in deadlock. Just my guess at what is happening.

Edit: Spurred to investigate online, I found this:

http://www.fixya.com/support/t15854834-tannoy_subwoofer_sleep_mode_problems

So, it may just be that the signal is being sent by the amp but at too low a level. l will investigate further. I could increase the volume on the amp and decrease that on the sub and see if that makes them talk to one another.
 

Black Hole

May contain traces of nut
I could increase the volume on the amp and decrease that on the sub and see if that makes them talk to one another.
That sounds along the right lines. I had a vaguely similar problem with some wireless headphones - the signal from the TV jack was at too low a level to keep the transmitter awake in quiet passages, but boosting the volume meant blasting the sound out when unplugging (if I forgot to reduce the sound first).

In any case, isn't it better to source at maximum (undistorted) level and attenuate at the final stage?
 
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Mike0001

Well-Known Member
That sounds along the right lines. I had a vaguely similar problem with some wireless headphones - the signal from the TV jack was at too low a level to keep the transmitter awake in quiet passages, but boosting the volume meant blasting the sound out when unplugging (if I forgot to reduce the sound first).

In any case, isn't it better to source at maximum (undistorted) level and attenuate at the final stage?

Thanks, BH. Getting there...hampered by the fact that the sub takes 15 minutes to reach sleep mode.

Tried +10dB on the amp, then went to +20dB before the sub reacted. I wonder whether this will really be a solution. I can see the sub switching itself on and off depending on the LFE level! I may revert to Plan B, which I know works!

Anyway, the amp is detecting the sub, you were right, so that part of the mystery is solved.:)
 
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Mike0001

Well-Known Member
That sounds along the right lines.

Sadly, it is hit and miss. Sometimes the sub switches on, even at +20dB at the amp, other times it remains off. Actually, equalization sets the sub level at -15dB (it depends what gain you have set physically on the sub) and changing -15dB to +10dB doesn't always bring it out of sleep mode.

I have reverted to the power-saver switch triggered by the amp. The sub's sleep feature wasn't something I bought it for, so I am not too worried about disabling it.

On the positive side, however, I have discovered that I like the sub volume a lot higher than Audyssey equalization sets it at, so after this discussion, my listening experience has improved. Thanks guys!

So that you could make a big thing of it on the box to try to fool people that it is a feature that will save them time on a daily basis.

Possibly. Much of technology seems to be like that. I don't recall this feature being prominent in the spec when I bought it, though. It was all about watts per channel, number of channels and number of HDMI inputs.

My previous Yamaha receiver used to auto-detect the speakers at setup. It would send a test tone to each, then decide there was no input at its microphone. This Onkyo doesn't even send a test signal to any missing speakers if some of its 9+2 are missing. (I only have 5+1, by the way.) 9+2? 7+2? I don't have enough speakers to test those. I noticed that one of my blu-ray disks is detected as 7+0, though. I don't think I would like 7 full sized speakers surrounding me, except in a cinema. :eek:
 

Black Hole

May contain traces of nut
"ABS" on the tail of a car was useful in the days when it was rare, it warned those given to driving too close behind that this particular driver might jam his brakes on at any moment, not having to apply due consideration to skid risk etc. Besides, being an expensive but otherwise invisible option, they needed something to show off to their golfing buddies. I don't put it in the same category as pre-sale feature inflation.
 

gomezz

Well-Known Member
Have you not asked them why their kit is too clever for its own (or rather its owner's) good?
 
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Mike0001

Well-Known Member
Have you not asked them why their kit is too clever for its own (or rather its owner's) good?

I now think the problem may lie with the subwoofer, or a feature of it. It just isn't consistently switching on. Sometimes you can increase the amp volume on the sub channel and trigger it but at other times it doesn't work. As I thought I made clear above, and as BH pointed out, the amp probably is not blanking the sub channel as I originally thought, just the powered channels.

Anyway, I prefer Yamaha amps, but a suitable one wasn't available when I bought this. All the modern ones are internet enabled so they can download firmware updates. There are issues with this older model in that it sometimes blocks HDMI HDCP content. There is no way to update it, though.

http://www.securityforcesoutheast.com/pdf/Onkyo-TX-SR608_manual.pdf
 
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