Load issue??? [SOLVED]

Snow day today so I'm in the home studio. Earlier, I was playing my Mark V, Ch3 Extreme @ 45 watts volume between 10 & 11 o'clock, using TorpedoLive. About 30 minutes into playing, I experienced a rush of white noise for a few seconds and then the amps 4A fuse blew. Installed a 3A to be safe and re-routed to an 8ohm cab. All is working fine again but I'm hesitant to connect back up to the TL. Any ideas on this?

Hi BigDog,

we answered your message on the Help Desk.

Please remember we are based in France and can't answer the questions when it is night here.

guillaume_pille":y3sq9vc3 said:

Hi BigDog,

we answered your message on the Help Desk.

Please remember we are based in France and can't answer the questions when it is night here.

Click to expand...

I have a new Torpedo Live inbound. Would you care to share the answer to the question for the benefit of the rest of us?


Steve

guillaume_pille":1qniyq9o said:

Hi BigDog,

we answered your message on the Help Desk.

Please remember we are based in France and can't answer the questions when it is night here.

Click to expand...

Did receive the reply. I posted here for any local input as well as contacting the help desk. I will post the reply and results when I have a chance to test. So far I've pulled the chassis out to access and test the tubes, which I will do next.
Thanks

Well, right now I asked a few question to BigDog and didn't received an answer yet.

We found that the Mesa Dual Rectifier was a little weak when pushed hard but we have no problem with the Mark V so far.

So the first thing is to test with the cabinet under the same conditions (same volume, same time) to see if the amp can take it.

Some people think that any amp can be pushed at max volume with no problem. I am afraid that is not always possible.

In the present case the fuse was blown and everything seems to be fine, an external cause like a power surge (sorry if this is not correct english, I am talking of a short increase of the network voltage) is possible. Happens often on stage.

Anyway, right now it is hard to understand what happened.

There is no real difference between the Torpedo Live load impedance and a speaker cabinet impedance.

Cross posts.

Ok Chris.

Test; One power tube is now bad. Replaced tube, connected cab and played for an hour with no issue. I will test with the Torpedo tonight.

Please keep in mind that:

1- the max volume of an amp is usually way before the max position of the knob
2- playing the amp at high volume (even on a loadbox) will shorten the life of the tube

I alway recommend to use the amp at the same volume that what you could use at a rehearsal level, if you have to play often. Otherwise the tubes will get old quite soon.

If the the unit is rated for 100 watts @ 8ohm, you certainly would not want to dime a 100 watt amp through it. The amp will peak higher than that and then comes trouble.

Meanwhile, I got mine today. I am just using it as a throughput DI for sending a signal to the FOH mixer and using a cab. Great way to control the signal quality/tone/EQ to the FOH.

Steve

Never have maxed the master volume. Have it set just the same, between 10 and 11 o'clock, when playing with a cab or the T-Live.
It turns out, after all, a power tube on the MK V went bad when using the T-Live. Re-tubed, back in business.

BigDog":dytqdd1d said:

Never have maxed the master volume. Have it set just the same, between 10 and 11 o'clock, when playing with a cab or the T-Live.
It turns out, after all, a power tube on the MK V went bad when using the T-Live. Re-tubed, back in business.

Click to expand...

I saw where you were at half power, so it should have been well safe. I was making more of a general statement. I had the same thing with an Ultimate Attenuator, running a 100 watt Super Lead at full tilt. Blew the fuses in it several times. Come to find out I was exceeding the design of the attenuator.

The Ultimate Attenuator shows a 30 Ohms load to your amp, this could be an issue in some case. We keep a "real" 8 Ohms load in our products so we don't have to face this kind of issue.

The downside is we have to design our product to dissipate more.

With most 100 W amps, when you have huge amounts of distorsion, you can have more than 150 W RMS (not peak, RMS) at the output. For example the Marshall 410 sends 150 W RMS when maxed, a Dual Rectifier nearly 160W.

When going to those levels, most power supplies won't behave correctly for a long time, and the tubes will suffer form accelerated aging.

I don't know the Mark V schematics, but if the 45W mode is done by using only 2 power amp tubes instead of 4, playing at high volume will be very demanding for those 2 tubes.