Well, still trying some tests with speakers
& still not a lot of luck. I have contacted the Outlaws and have been doing a few different checks for Steve. I have disconnected all of my Studio v.3's & checked all wiring.

There are no shorts in any in wall wires. I have connected the fronts & the center with different wires to eliminate the in wall wires. I have been running the system at -05 db with the same material for the same period of time and have still encountered the amp dropping channels.

I have not had the circuit breaker trip again but have had the channels drop out at various times when moving around the amp's outputs. I have left the 950 set to 7 channel stereo throughout all of the testing.

With only 2 speakers playing at a time, it takes longer for the 770 to drop out compared to when all 7 channels are playing at -05 db. I played it at 00 db for a few minutes - cuts out very quickly. I have measured the top of the amp with an infrared
heat gun & it gets to about 160 degrees with any 2 channels running, above those respective channels.

It measures that temp. all across the top of the amplifier with all 7 channels playing at -05 db. I don't know if I have to run it with fans or what. The equip. rack it is in is adjacent to another room & open to the back with plenty of room above the amp.

Is there a way to post some pictures of my setup here? Maybe someone will spot something that could be causing this???

This may have been mentioned before, but what's your electrical situation? In other words, how much stuff do you have on the same circuit as the 770? If you've already tripped a power breaker, then this whole thing may be related to your electrical system. Also, just running two channels and getting better results would point towards that sort of problem.

Maybe some of the more technical electrical guys around here can talk a bit more on that...

Jas1: Hopefully your saga of trouble will come to a happy solution soon. You have been great about coming back to this post and keeping us up-to-date. I appreciate it!

As to pictures, you would need to host them elsewhere and reference them from your posting here.

Jason J has a point. There are some power issues that could affect this, even if they are rare. The easiest test is for sufficient voltage under load. Either while your audio gear is operating at the –5db level, or while all your video/audio gear is off but you run a toaster or a 1600/1800 watt hair dryer on high on that circuit, CAREFULLY* measure the supply voltage. The toaster/dryer test will provide a constantly large load, whereas your audio gear will draw a varying amount depending on the moment-by-moment demands of the audio signal. If the circuit measures between 110vac and 120vac under load, it is unlikely that you have significant mains power issues. If it immediately or over time falls to 97vac or something, that would be a definite source of trouble. *Only perform the measurement if you are certain you can do so without causing harm.

I doubt you’ll find a power problem, but who knows until it is checked?


[This message has been edited by bestbang4thebuck (edited April 27, 2004).]

Wow, weird problem. It actually sounds like the voltage is too high if all channels run hot. This is a way long shot, but could the amp be wired for 100V operation and running at 115? I don't even know if Outlaw offers that voltage option, but I do think something is runnin up the B+ lines. I guess it could also be possible that the bias is too high in the output stage, but this seems unlikely as all channels seem to have the problem and all the amp modules would be built and tested seperately. 160 is way hotter than my 755 runs. It is warm to the touch, but 160 is basically untouchable. It really sounds like it is going back to outlaw for return. I will be very curious what the final outcome will be.

The air above my 750 gets up to around 95F when it's been heavily driven for an extended period of time (couple hours) in a space that is more enclosed than I would like. I don't know what the surface temp is, but I don't think it's close to 160 - probably closer to 110 or less.

------------------
gonk -- 950 Review | LFM-1 Review | Pre/Pro Comparison Chart | Saloon Links

Oil Can - you an a&p mech too???

Yes, I got my license in 1974.

Jas1 since you have been doing some voltage testing I would suggest one other. Check the AC voltage at the speaker terminals while playing loud passages or test tones. My speakers are pretty inefficient, dipping to 3.6 Ohms at certain frequencies an I have never had a heating problem even after many hours of loud playing. While playing LOUD I have measured the voltages by placing the meter across the biding posts and setting the meter to capture the highest voltage. This loud playing will ussually give reading peaks about 20 VAC which works out to around 100 watts or 5 amps. Doing this may give you some idea of how much current individual speakers are pulling which may in turn help diagnose the problem. You could also use this method to check at the speakers first and then at the amp to see if the wiring is adding much of a load.

If this process of diagnosing is flawed I am sure someone will post with corrections

It has been a while since I have been back to report on my 770 issues. I have gone over the speaker connections, ran new wires across the floor, used different power sources, measured resistances, voltages, etc., etc., while operating the 770.

We have played a few movies now and the 770 works great for that. Without a constant loud volume, it works great.

I have accepted the fact that this amplifier does not dissipate enough heat to play music at the levels that I have been testing it at without a thermal shut down occurring. I will continue to do some testing as advised by you guys that are offering your help.

I have had a few conversations with the Outlaws and they have been supportive.
But the ball is in my court as they have offered to check it if I want to send it back. I am in Canada & with all the shipping
& duty issues, I don't know if I will.

I suspect that if they do test it they may find it OK for what they are using as a test system. I would like to have someone test it with the same speakers, 2 runs of 14 gauge wire to each, with the same material & volume levels to compare apples to apples. The material I have been using (to stay consistent) is Metallica - Master of Puppets at -05 db.

Even though I have an open back rack, with 8" + clearance above the 770 and at normal room temperature, I am planning to run a vent from the rack to a bathroom fan somewhere in the ceiling, or have a duct to the cold air return installed. That may cure it.

Of course, my visits to my B&M store, who sold me my Paradigms as well as many other pieces of gear over the years and who wanted to sell me Anthem product, see my with my hat in my hand("We told you so"). Would the Anthem stuff thermally shut down? I don't know.
The 950/770 combo is impressive for movies, and I think that they certainly compare to the AVM 20 or the Anthem power amps, (forget the difference in price) after spending hours listening to them in the store.

I suppose for a true apples-to-apples comparison, someone would need to mimic your setup exactly, including the exact music that you’re playing when the 770 overheats.

But for a kind of Red Delicious-to-Gala apple comparison, one might only need to have the same load impedance that your speakers provide driven by a 950/770 combo in the same mode and at similar electrical levels.

My speakers are 6-ohm nominal x 7, driven by a 950/770 combo. In what way could you measure the output level of your 770 that leads to overheating?