I just Fried fairly expensive AVR which is NOT mine

[restorer-john]

So either a complex modelling using analogue electronics, or accurately montior the current in a micro and implement in software.

The classic uPC1237HA SIP protector IC has been practically industry standard for around 35 years in analogue, conventional amplifiers and covers AC power on/off detect, DC offset trigger, over current (set by signal conditioning time integration RC or active), turn on mute delay and configurable reset/latch time. The IC is still made today and if correctly implemented, amplifiers using it are set and forget style protected.

Over temp wasn't really much of a problem in the good old days, because everything sold was compliant with FTC reqs, which meant overheating an amplifier in a domestic situation was virtually unheard of. Not these days, sadly.

Toshiba also had the TA-7317 SIP9 which is functionally virtually identical.

I'll take those ICs anyday over some stinkin' micro monitored system full of bugs and likely to lockup needing a firmware update when you least expect it.

 

[thin bLue]

Oh, my! Soooo many comments!!! Thanks a Lot! I'll try to answer little by little.
Please be patient. Sorry!!!!

 

[thin bLue]

Meh, I used to run my amps into 0.25ohm each when I was competing, with impedance rise I got approx 0.8ohm and 7k per pair of strapped 5k rms amps I was chasing world records and was third in the world at one point in the late 2000’s

WOW Do you have some Pics of them? It would be interesting!

 

[thin bLue]

For bettors!

Damage report: I think it should be treated as confidential until the repair and billing is completely finished. Please wait a little longer. We already know information about some things(not full-detail yet), but we can't disclose them to the public.

 

[thin bLue]

@thin bLue ... any chance of taking the cover off and looking around inside for the "smoke source" and posting a picture?

If he can't do that, a flash light can be used to see inside through the vents. One's nose is also a great diagnostic tool with respect to equipment that has smoked out.

Yeah the professor at uni would do that.

One day in electronics lab, the prof was helping Lutz with this breadboard, and I saw the waveform on the scope.
Dr. E. Had his nose on the board like a bloodhound on the scent.

I asked if I could help…
They said please…

And I slammed the box down as I flipped the power switch on, which made it go from passive to powered.
Dr E. said, “what did I you to make it work?”
I said, “The contacts get corroded and slamming it cleans them.”

After Lutz left, Dr. E said, “That was quite a magic trick, but what did you really do?”
I said, “I turned on the power switch.”
He said, “why did you slam it down?”
I said, “to obfuscate the causal mechanism So I coudl flip the switch up.”
He said, “well done Holmz… well done.“

It was immediately delivered to the owner in the afternoon of the same day (I fried it at dawn), and the owner immediately put it in the service center. So, unfortunately, we lost the chance to directly observe its internal organs.

 

[SynthesisCinema]

Arcam`s AVR30 flagship receiver at 6600$ went into smoke after running B&W 800 serie D3 or D4 speakers on other forum and there was lot of burned parts. Even expensive Anthem MCA525 power amp had issues with 2ohm loads, remember @peng the thread at Audioholics? So if that kind of product can´t do it then are people really expecting 3500$ av-receiver to pass this kind of torture test as no one with some brain activity wouldn´t run such type of speakers with A8A or any receivers as they are not what they used to be back in the days!

Yamaha actually printed the dynamic power specs for 2Ω on earlier gen models which aren`t that different from current ones. A3080 is RX-A6A and A8A that died in this test probably has marginally larger power supply to power the two extra channels, at least bigger caps. Still at the back of the unit of A8A we see 4Ω min for front L/R!

• Dynamic Power (IHF) [RX-A3080] Front L/R (8/6/4/2 Ω) ........................................ 175/220/295/410 W

Yamaha has aggressive protection circuits, but for some reason they didn´t activate on this test. Gene couldn´t pass the 4/8Ω dynamic power tests and in the 7 channel multich test protection activated limiting power output probably to keep the unit cooler than competition and to have that reliability Yamaha is known from. Still plenty of power for 2ch 4Ω loads, actually more than any competitor shows on 1kHz power vs. distortion tests so they haven´t skimped on power supply size if someone is worried.

Audioholics test of A6A:

Even with the nannies turned off, Yamaha has built in protection to limit power with multiple channels driven as you can see the distortion rise to 10% (hard clipping) with 4 channels driven. I’ve seen this type of behavior before on other Yamaha receivers we’ve tested. With 7CH driven, the RX-A6A limits power to 52 watts. This is not surprising as Yamaha has always set their limiters very conservatively. It’s unlikely you would trip this limiter with real program material, however.

Editorial Note About Dynamic Power Testing: The Yamaha RX-A6A is the first receiver I’ve been unable to perform CEA 2006 short dynamic burst testing since the nannies prevented the receiver to be driven into the distortion threshold for high dynamic transients.

 

[RKV1]

For bettors!

Damage report: I think it should be treated as confidential until the repair and billing is completely finished. Please wait a little longer. We already know information about some things(not full-detail yet), but we can't disclose them to the public.

I have outputs to win, dual emitter resistors to place and output Zobel resistor to show. "No problem found"/ firmware update as a 50 to 1 long shot but closing fast.

 

[audiofooled]

The classic uPC1237HA SIP protector IC has been practically industry standard for around 35 years in analogue, conventional amplifiers and covers AC power on/off detect, DC offset trigger, over current (set by signal conditioning time integration RC or active), turn on mute delay and configurable reset/latch time. The IC is still made today and if correctly implemented, amplifiers using it are set and forget style protected.

Over temp wasn't really much of a problem in the good old days, because everything sold was compliant with FTC reqs, which meant overheating an amplifier in a domestic situation was virtually unheard of. Not these days, sadly.

Toshiba also had the TA-7317 SIP9 which is functionally virtually identical.

View attachment 254959


I'll take those ICs anyday over some stinkin' micro monitored system full of bugs and likely to lockup needing a firmware update when you least expect it.

There's also this:

 

[peng]

Arcam`s AVR30 flagship receiver at 6600$ went into smoke after running B&W 800 serie D3 or D4 speakers on other forum and there was lot of burned parts. Even expensive Anthem MCA525 power amp had issues with 2ohm loads, remember @peng the thread at Audioholics? So if that kind of product can´t do it then are people really expecting 3500$ av-receiver to pass this kind of torture test as no one with some brain activity wouldn´t run such type of speakers with A8A or any receivers as they are not what they used to be back in the days!

Yamaha actually printed the dynamic power specs for 2Ω on earlier gen models which aren`t that different from current ones. A3080 is RX-A6A and A8A that died in this test probably has marginally larger power supply to power the two extra channels, at least bigger caps. Still at the back of the unit of A8A we see 4Ω min for front L/R!

• Dynamic Power (IHF) [RX-A3080] Front L/R (8/6/4/2 Ω) ........................................ 175/220/295/410 W

Yamaha has aggressive protection circuits, but for some reason they didn´t activate on this test. Gene couldn´t pass the 4/8Ω dynamic power tests and in the 7 channel multich test protection activated limiting power output probably to keep the unit cooler than competition and to have that reliability Yamaha is known from. Still plenty of power for 2ch 4Ω loads, actually more than any competitor shows on 1kHz power vs. distortion tests so they haven´t skimped on power supply size if someone is worried.

Again, please be reminded that a single number spec with no qualifications is not that useful. Either we make sure we overkill (that is, think that we are..), or look for the impedance and phase angle vs frequency graph so you won't be mislead by a single number such as 4 ohm nominal, 2 ohm dip.

For example, if the 2 ohm dip is a wide one, like an octave or more, even 1/2 octave, those Yamaha's 400 W dynamic ratings will not do you any good because it could be for only 20 ms or a little longer and it could be at very high distortions as well, thereby endangering those diamond tweeters.

There is another way, that is, use the volume dial wisely. For example, if one us the RX-A3080 to drive a pair of SVS Ultra tower with volume set to -10, then after upgrading to a pair of B&W 800 d4, dial the volume down to -25 then you can listen to those speakers all day with no fear.

Assuming the protection system sense only current but not impedance, then any AVR can drive 2 ohm speakers as long as you dial the volume down enough, accordingly. That's based on electrical theory, Ohm's law, power formula don't lie, people do, or they told you half the story after the fact..

In practice though, I would not use any AVR to power my B&W diamond speakers, not even the baby 804 d4 let along the gigantic 800 d4.

 

[smile nya]

hello. I am the owner of the A8A in this fun case.

In Korea, Yamaha's A/S is the best among all AVR and home audio amplifier companies.
I wasn't too worried about the overall damage etc.
As expected, fortunately, the repair was completed in one day after I left it (it took two days to bring the parts), and I brought it well.

I've been using the Yamaha a8a instead of the Denon x3800h for the past few days and I'm enjoying it.

The service center informed me that the broken part was the amplifier board of the front L/R. Perhaps sparks flew on the board, and since L and R share the same board, they repaired it together. Parts cost about $140. Service cost is about 50$
Unfortunately, I did not see the repair process myself.
Thin blue also directly paid for the after-sales service.

This work is a bit of a happening, and I think it is a passion to measure hard.
The unfortunate thing is that the measurement of the A8A could not be partially completed due to that, and Thin blue promised to re-measure sooner or later.


I've heard a little bit, but I'm looking forward to the finished result.
Because in our community in Korea, he is the rising 'amp measurement reviewer'.
Have a nice day everyone.



*It may be awkward because I use a translator because I am not good at English.

 

[restorer-john]

*It may be awkward because I use a translator because I am not good at English.

No excuses needed.

Sounds like they just did an entire amp module replacement. Pretty standard these days for so-called technicians, but it does ensure you have a perfect unit, not a patched lot of vaporised tracks and a charred PCB.

 

[TheBatsEar]

the broken part was the amplifier board of the front L/R. Perhaps sparks flew on the board, and since L and R share the same board, they repaired it together.

Cheers for the update.
Hope this incident doesn't diminish the fun you have using the A8A.

 

[smile nya]

No excuses needed.

Sounds like they just did an entire amp module replacement. Pretty standard these days for so-called technicians, but it does ensure you have a perfect unit, not a patched lot of vaporised tracks and a charred PCB.

Thank you for your kind and detailed explanation!
In fact, the device is working fine without any problems.

Have a good day!

 

[smile nya]

Cheers for the update.
Hope this incident doesn't diminish the fun you have using the A8A.

I want the A8A to be well-received, but if not, I want the Yamaha to do a little more.
I am also concerned because I have learned that a newer, more expensive product does not guarantee good quality.
have a nice day!!!

 

[GXAlan]

@thin bLue : Any updates to your RX-A8A measurements? Can you post what you already were able to measure before damage?

 

[thin bLue]

Yamaha RX-A8A Review

람쓰 the member of our community kindly purchased it himself with his own money and asked me to measure it. I fried it. Then Repaired. Further more he just provide another Brand New One!!! And I made some mistake in measurements that made me to retest them. So he asked to Yamaha Korea lent their...

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