Fireworks in an Audio Research VT200

From the above posts, sounded like no speakers were damaged in any incidences. I have heard drawback of ARC amp - using one pot to bias 4 or more tubes leaving one tube to work much harder than others. Other brand, like Jadis or Sonic Frontiers, give each tube individual trim pot to bias the tube and consequently reduce load differences. Not sure how true this statement is.

So the 6C33 in BAT/Tenor also arc easily like 6550? I would think if it is good enough to be in a Russian Mig, it should be build like a tank. I ask because I now own VK-150, would like to keep my house and speakers intact. What can user do to prevent arcing short of changing tubes every other week?

My VT200mk2 stopped John Denver during an immense crescendo with a tube arc & an impressive white flash of blown resistor underneath -yes that smell is quite pungent - AR do fireproof their resistors. The 6550s were about 1200 hrs in but I replaced the lot. Leonard at AR is very helpful.
Maybe I should keep a fire extinguisher at hand given the above tales! Doa nt of you have experience with tube rolling in VT200mk2?
Doctor from durham, england

Hi
I have repaired several ARC VT 200 amps with this situation.
It typically starts when one of the output tubes shorts and causes an arc in the plate or cathode ciucuit. It burns away some of the conducting trace ( hence the fireball) and sometimes takes out a resistor on the cathode or screen.The related tube should be tossed out and replaced.

I WOULD NOT CONTINUE TO USE THE AMP IN THIS CONDITION.....

Right now it is an easy and inexpensive fix.
Best to keep it that way.
Good luck.

Mike

The 200 banks several tubes onto one adjustment

I have had that happen quite a few times with various ARC amps. Usually it is a tube arching.
Sometimes it will take out a resistor. I would definately check the tubes at least.

Excitement is not uncommon with tube amps. 6550s, KT-88s and especially 6C33Bs can arc across grids and take out other devices in the system. My BAT VK-60s which use 6C33B power tubes have been far less reliable than the ARC Classic 150s I enjoyed for years which used 6550 tubes. In any case it is unwise not to atleast pop the top and look for other damage before changing a blown tube and restaring your system. Sniffing the box for a cooked resister at the very least should be done. The Bats have fuses attached to each power tube and still take out resisters when they blow. I have been advised to only employ UL fuses because they are more precise. Also power amps should be checked out once in a while to ensure that the power supply voltages still meet manufacturers specs. Good luck.
Jeff

I've had tubes blow in an ARC CA-50 & a VT100 with a loud electrical snap & a puff of smoke. In all cases the amps still worked with one tube unlit & exploded resistors next to the unlit tube. Replaced the tube & resistors & life was good again. (In one instance the resistor I "retrofited" wasn't "flameproof" & when it "blew" a very brief wisp of flame was visible.) These were all non-ARC sourced svetlana 6550c's. This has occurred once in the CA-50 & twice in the VT100 (different tube locations) I always check the adjacent resistors when suspecting a tube problem...

I would certainly like to hear about what caused this problem as I use a VT 200 in my system. My first thought was non-standard output tubes, but I assume this not to be the case. These amps are pretty picky about what they will accept in the way of tubes and tube matching. I certainly agree that I would by no means continue to play the amp until the cause can be determined. Despite the cost, I would suggest returing the amp to ARC for repair. ARC is pretty good about making repairs at no charge or at cost if they believe there may have been a component defect. Good luck.

Kurt,

A year ago I was actually told by Counterpoint that they never had an amp catch fire. Hm!

The ARC amps my father had when i was a kid were D-60's and believe it or not, solid state. They'd been installed in a custom cabinet by the high end audio shop he got them from. I was listening to Neil Young at an ear bleeding level and luckily I happened to walk back in from the yard just in time to see that the whole thing was on fire...right underneath dad's oracle turntable. No idea why this happened (whether there wasn't enough circulation in the cabinet or what) but i think about that fire every time i leave the house with my COUNTERPOINTS on.

I'm hoping someone can provide a reason here why not to worry. Then maybe they can talk to dear ol' dad.

Funny you should ask. I was relaxing....... reading a magazine with a little Ella Fitzgerald playing in the background the other night when all of a sudden WWHAM, HOLY MOTHER OF GOD!!!!!!!!!!!! My entire living room lit up with a wonderful lightning display comming from my ARC VT200. I unplugged it (After I came back from the bathroom), called my local dealer and took it to a Very reputable local tech that they recommended. He fixed the amp (he thought), I brought it home and the second time I turned it on guess what.............. Well the amp is back in the shop and I am wondering what the hell is going on.

Funny you are having the same troubles. I would like to hear what you come up with on this, so please follow up.

Oh yeah, this all happened about six months after the amp had come back from ARC having been fully retubed and gone over.

I am becomming very frustrated as you can imagine.

I would definitely call ARC or your local ARC dealer ASAP. My guess is the flash you saw was a fuse that popped.

Okay Guys, you officially have me scared!

I always thought that this only happened to "power" amps manufactured components from so-so companies.
(This happened to me with a Counterpoint amp one time, as one of the tubes blew and a foot tall flame shot out of the top).

I do not consider ARC to be a so-so company, in fact, I own two ARC components. I own a LS-2 preamp (with one tube) and a PH-3 phono preamp (with 3 tubes).

Question: Has anyone ever had an incident with a tube preamp, (in particular an ARC preamp) where the unit either blew up the tubes or caught fire.

I ask, because I sometime leave them on when I am not home. The units sound best when left on for an hour or more before listening (as most tube unit do).

Thanks for your input!

Agree with Cytocycle. Do NOT continue playing. I set fire to a wood cabinet because of a pair of faulty ARC amps and almost burned my father's house down.

Call Audio Research ASAP, they have excellent support