Gryphon Colosseum stopped working

Jan 28, 2018
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#1
I bought a used Gryphon Colosseum stereo amp about nine months ago from a seller who was upgrading to the Gryphon Mephisto Solos. I consider the Colosseum to be a destination amp for me, I plan on keeping it for a long time. I use it to drive a pair of Cantatas.

So, the amp has been running fine for the past nine months. A few times it detected DC on an input but recycled itself and was fine after that. However, a couple of days ago, when I got back from a trip out of town I turned on my source components, waited a bit, and then hit the power button on the Colosseum. The red Gryphon light on top immediately went out and the amp would not power up. I tried turning the bottom AC switch on and off but that didn't make any difference. I contacted Niels at Gryphon service and he told me to check the main AC fuse on the bottom of the unit. I did that and found that the fuse is still good, it has continuity.

We had a brown out when I was out of town but all of my other components are fine, and I can't understand why a brown out would have damaged the Colosseum as it sat in standby mode.

At this point, I guess I'm looking at bringing the amp into a service center, not an easy feat as the shipping container is out in Connecticut, at my mom's house, as I have no storage space. Luckily, there is a service center, SoundSmith, in Peekskill, in New York state. I live in New York City, and don't own a truck or a car but can make it all happen with a rental van. Of course, it's going to cost a lot.

Are there any other fuses that might have blown? Any thoughts from anybody?

For me, 2019 is shaping up to be the year the music died. ;-( At least my classical guitars still work.

Best,

Larry
 
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RogerD

Well-Known Member
May 23, 2010
3,401
83
48
BiggestLittleCity
#2
Just a long shot. Do you have the amp on a separate circuit breaker. Good luck.
 
Jan 28, 2018
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#3
Yeah, the amp is on its own 20amp circuit. I plugged a lamp in where the amp was plugged and it works fine.
 

DaveyF

Well-Known Member
Aug 1, 2010
6,135
133
63
La Jolla, Calif USA
#4
If you had a spike on the line, it may be possible that something was overloaded in the amp, although I would have thought the fuse would protect against that.
If the power cord is one that is detachable, I would suggest you try and unplug it at the iec and then re-connect. Sometimes there can be slightly poor conductivity at the iec connection, leading to power on issues. Making sure the connection there is a good one is worth a try.
 
Jan 28, 2018
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#5
I would have thought the fuse would have protected against any spike but I don't know. All of my other audio equipment appears to be fine, my computer is fine, the TV is ok, I didn't notice that anything was hurt by a surge. The amp was on in standby mode with the top red light on, just like always.

I tried plugging and unplugging the power cord at the base of the amp a number of times but it didn't make any difference.
 
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Aug 10, 2018
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Southern California
#6
Fuses and breakers are designed to literally melt or trip/open (for breakers) due to excessive current draw. They further vary on how long a given current will be allowed before failure of the fuse. The voltage rating has to do with ability to prevent arcing from high voltage breakdown. A voltage spike will typically not blow a fuse but will electrostatically damage other parts which lead to excessive current draw and a subsequent blown fuse. There are other types of devices which are designed to very rapidly interrupt or absorb an excessive voltage spike. These are usually found in power strips and the protection circuits of some equipment. This is why it is recommended to disconnect items from the electrical connections during a lightning storm.

Motors/generators on a line can create large localized voltage spikes if current is suddenly removed. Think of the big flash/arc if you pull the plug on a vacuum cleaner that's still running. This is because high inductance circuits resist a sudden change in current. Pull the plug and the inductor current tries to maintain itself and decrease gradulally, but since that can't be done you instead you get a voltage spike at the plug/outlet junction, causing an arc of current when the high voltage breaks down the air gap.

Perhaps an effect of the brown out you mentioned. Is your equipment on the same electrical circuit as the AC, Fridge, etc?
 
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Aug 10, 2018
94
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Southern California
#7
This is a huge amp. Does the amp use a 240V connection? Perhaps one phase is down. You should measure 120V AC from each phase to the neutral connection and 240V between the two live connections.
 
Jan 28, 2018
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#8
Yes, it is a huge amp and is built like a tank.

The amp is on a 120v connection, a dedicated 20amp circuit. I had two dedicated 20amp circuits installed, each to a hospital grade outlet. The source components are on one 20a circuit and the amp is on the other.

None of my gear is on the same circuits as the fridge or the air conditioners. The fridge is fine and the ACs are too, I assume, I have not tried them.

It’s just strange that the standby light was on when I went to power up, just like normal, and then it went off when I pressed the power switch.

My wife is blaming me for not forseeing a brown out when we went out of town for five days. Sigh. I do unplug during electrical storms but this is winter.
 
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Likes: Lagonda
Aug 10, 2018
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Southern California
#9
I don't think a brown out would cause the damage. The resulting voltage spike/surge as it starts and stops might. The surge might have damaged something in the amp but not blown the fuse. Then when you turn the amp on the application of power to the various circuits may have caused the failure. Does the red Gryphon light still stay illuminated? Some amps have built in diagnostics. The Classe 5100 amp, and others in their line, are an example. If the Gryphon does, you may be able to connect a computer to it to figure out what is being reported.
 
Jan 28, 2018
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#10
The top red Gryphon light will not go on. Perhaps there is a fuse for that, I don’t know. The amp has a lot of built in diagnostics but I don’t think I can access them myself.
 
Jan 28, 2018
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#12
I’m not sure what you mean by pulling the AC connection. The amp definitely detects a DC offset on input, that has happened a couple of times to me.
 
Aug 10, 2018
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Southern California
#13
I mean, first disconnect the speakers and left/right input connections, then pull the AC plug out and then plug the AC back in. Try to turn on the amp without signal or speaker connections. This will test for a DC offset on the input or a short on the outputs.
 
Aug 10, 2018
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Southern California
#14
If the amp will power up without any input or speaker connections, then try connecting the speakers. If all is well then try connecting the left/right input wires. If that causes a failure, the problem is with the preamp or whatever Is driving the amplifier.
 
Aug 10, 2018
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Southern California
#15
Large power amps will often have these protection circuits since they are capable of destroying pretty much any speaker hooked up to them. Especially large solid state amps which are DC coupled. Any sort of DC offset at the input will be amplified. Let's say there is a small 100mV input offset. That can be amplified by a factor of 100 to 1000, which would do some serious heating up of a speaker voice coil which may have an AC impedance of 8 ohms but at DC it might only have a resistive value of a fraction of an ohm. a gain of 100 for a 100mV offset would result in 10V on perhaps a .1 ohm resistance would be a potential 1000W.
 
Jun 26, 2014
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#16
I think you have done everything possible.
My Colosseum did something very similar and needed a significant repair.
I hope I am wrong of course.
It takes quite a lot for these amps not to work.
 
Jan 28, 2018
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#17
Thanks, everybody. I’ll try some of the tips and report back.

My heart sank after reading the post above.

The sound was so sweet, I miss it so much. I, and other people, have been amazed by the uncanny realism of vocals, the separation of instruments, everything. Sigh.

I’ll get it fixed because nothing compares to class A amplification. My rebuilt Sumo Gold ran for eight solid years and just dropped a channel every once in a while due to heat. I thought Class A amps were pretty much bulletproof, I guess I was wrong.

This amp is not that old and the previous owner told me he ran it in low bias all the time. In the winter, I run it on high bias, the heck with the electric bill, which really isn’t that bad.
 
Aug 10, 2018
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Southern California
#18
Larry, Please don't be disillusioned. I've owned nothing but Class A solid state amps for the last 20 years. Accuphase, Luxman, Pass (2 versions), all running at full bias all the time. They're typically heavy because they have lots of heat dissipating area. They wlll be typically very warm but not so hot that you can't keep your hands on them for many seconds. For this reason, they shouldn't be inherently less reliable. But any electronic device can fail. In linear (non-switching) amplifiers, like yours, it is most often the large capacitors after 15 to 20 years or so.

Believe me, tube power amps are way more problematic. Let's hope the problem is elsewhere.

The expense of servicing your amp will be due to its bulk: shipping, handling, etc. In the end, if it costs a couple thousand, compare the cost of the joy you get from your system to the pleasure you obtain from a nice car after paying auto insurance, depreciation, etc. which can typically be 10 to 20K per year. No rock chips, door dings, spilled drinks either. I'm assuming you can afford this since you have the amp in the first place.
 
Aug 10, 2018
94
36
18
Southern California
#19
Large power amps will often have these protection circuits since they are capable of destroying pretty much any speaker hooked up to them. Especially large solid state amps which are DC coupled. Any sort of DC offset at the input will be amplified. Let's say there is a small 100mV input offset. That can be amplified by a factor of 100 to 1000, which would do some serious heating up of a speaker voice coil which may have an AC impedance of 8 ohms but at DC it might only have a resistive value of a fraction of an ohm. a gain of 100 for a 100mV offset would result in 10V on perhaps a .1 ohm resistance would be a potential 1000W.
BTW, what I write here, about large power amps, is not meant to imply a flaw. It is meant as a fact and the reason why sophisticated protection circuits are used in them. The discussion of DC coupling and amplification is a design feature. The only "flaw" or "fault" discussed above would be a DC offset present in the signal supplied by the preamp, DAC, or other up-stream device. A large power amp without such protection circuits would be an incompetent, careless, and reckless design.
 
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Aug 10, 2018
94
36
18
Southern California
#20
Yes, it is a huge amp and is built like a tank.

The amp is on a 120v connection, a dedicated 20amp circuit. I had two dedicated 20amp circuits installed, each to a hospital grade outlet. The source components are on one 20a circuit and the amp is on the other.

None of my gear is on the same circuits as the fridge or the air conditioners. The fridge is fine and the ACs are too, I assume, I have not tried them.

It’s just strange that the standby light was on when I went to power up, just like normal, and then it went off when I pressed the power switch.

My wife is blaming me for not forseeing a brown out when we went out of town for five days. Sigh. I do unplug during electrical storms but this is winter.
o_O Rule number 1 is to not complain to your spouse when your expensive toy breaks. ;)
 

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