Using contact cleaner in tube sockets

  When you swapped tubes, did the problem happen in the other channel? If it did, then it must be the tube. If it didn't, then it must be something else. I have an MR-71 tube tuner. I have never used contact cleaner for the sockets. This is a good question...is contact cleaner recommended for tube sockets?

The problem was still the same channel after swapping tubes. I just now cleaned the sockets with the contact cleaner. The amp is warming up now and as I'm typing this, it's crackling on the same channel. So the cleaner did not work.

Ugh. I have the same amp. I love it! I just hate the shipping and maintenance costs.  Could be a capacitor or something. Speak to ARC.  You may need to have it sent in for service and have some minor repairs done.  I've done this a couple of times with mine...

I love the sound also! And I just got it Friday, tubes Monday! It was fine at first. This issue started this morning. Or maybe I didn't notice at first due to my excitement. I'd hate to have to return it to the seller.
Mark, was it expensive? I know shipping is not cheap, but the repairs?

@ sgonzalez33

My ARC VT100mkii which I just got, has a crackling from one of the channels. The tubes are new. When I first installed the tubes, it was fine.

New tubes? Installed and biased by someone who knew what he was doing?

You can’t just swap tubes around in a VT100 mkll. At least not the 6922 tubes.
The 6922 input and driver tubes must be biased. Failure to bias the 6922 tubes properly can damage tubes, blow screen resistors, and or damage circuit boards. Damage to the amp especially if the driver tubes are not biased properly.

Courtesy of Abe Collins
http://mycollins.net/audio/artube1.html

http://www.audioresearch.com/ContentsFiles/VT100%20MKII_BiasAdjust.pdf

Scroll down to bottom of page for schematic wiring diagram/s
http://www.arcdb.ws/VT100/VT100.html

http://www.audioresearch.com/ContentsFiles/VT100II_Manual.pdf

Jim

Biased the 6550cs myself. Didn't know the 6922s needed biasing as well. I was sent the amp and tubes separately. New tubes at that.
I guess I'll be opening a ticket with AR and shipping it to them. Any idea what this might cost me?

Were the 6922 individually numbered showing which tube socket they were to  be plugged into? Look near the base of the tubes for V1 through V8. If marked install tubes per diagram in owner manual.

Power tubes should be marked as well. (They are easy to bias if they are not though)
 
http://www.audioresearch.com/ContentsFiles/VT100II_Manual.pdf

Jim

There's no indication they were purchased from ARC and there are no markings. The 6550cs are Svetlanas and the 6922s are Electro-harmonix.
I will have to start with contacting the seller.

 Do you have an ARC dealer within a reasonable distance? If so I would ask him to have a look and see what he thinks. If he is a nice guy, he will help you figuring his good will may earn him a customer in the future. He should be able to check the bias.It could possibly be a bad driver tube. But it could also be something else like a bad cap. 

 I would take any sellers claim of tube life or new tubes with a grain of salt. When I buy a piece I always assume it will need new tubes. If the tubes are bad or not closely matched and you send it to ARC for repair. The first thing they will do is replace all the tubes. ARC tubes are expensive and can really add to the price of a repair. That is why trying to see if an ARC dealer will help is the first thing I would try. Maybe even buy replacement 6922 tubes from a reputable dealer and ask the ARC dealer to install and bias them. Even if there is a small charge it would be cheaper then sending the unit back to ARC. I buy my tubes from Jim McShane. He burns his tubes in a bit before matching them just like ARC. 

 Good luck, I hope it is something simple that can be easily fixed.

Try cleaning the tube pins. Make sure the bottom of the tube (the glass) is clean as well. Use your cleaner and a Q-tip to scrub the tube pins. 

I have always wondered why ARC neglected to mention in the owner manual that came with the VT50, VT100, Vt100 mkll, and VT200 that when replacing the small driver and input signal tubes they would need to be biased. There is no mention of it at all. Nor is there any mention the difficulty of preforming the biasing of the small signal tubes. It’s nothing like biasing the power tubes. Biasing the power tubes is a cake walk compared to biasing, correctly biasing, the 6922 tubes. Especially the driver tubes.

I would not be surprised if the seller of the OP’s Vt100 knew the new 6922 he bought for the amp and shipped with the amp needed to be biased once installed in the amp.

The reason ARC tubes for the VT100 are so expensive is because each section of each 6922 must be tightly, closely, matched to adjust, set, the bias to within ARC specs. Many tube vendors do not spend the time to match their 6922 tubes that will meet the tightly close matching that is needed. The closer, the tighter, the 6922 tubes are matched the easier it will be to bias the tubes within specs. Even then it can be a PITA. Biasing the 6922 tubes is not for the novice. Lethal DC voltage is present at points the multimeter probes will be connected.



Owner manual. No mention when retubing the 6922 tubes they must be biased.
http://www.audioresearch.com/ContentsFiles/VT100II_Manual.pdf

Could also be a loose pin in the socket. I had that same problem in an Octave V70se and it was loose pins in one socket

For cleaning tube socket female contacts and male tube pins I use  isopropyl alcohol.                                                          


 

jea48

I have always wondered why ARC neglected to mention in the owner manual that came with the VT50, VT100, Vt100 mkll, and VT200 that when replacing the small driver and input signal tubes they would need to be biased ... Biasing the 6922 tubes is not for the novice. Lethal DC voltage is present at points the multimeter probes will be connected.

An owner's manual and a service manual are two different things. As you note, biasing the 6922 tubes is not for a novice. The owner's manual does clearly state: "Refer servicing to your authorized Audio Research dealer or other qualified personnel."

cleeds,

"Refer servicing to your authorized Audio Research dealer or other qualified personnel."

As a rule retubing an amp should not require sending it back to the factory or to a qualified manufacture service center.

ARC should have made mentioned in the owner manual retubing the 6922 tubes required they would have to biased.

There used to be pictures on the Net showing VT100s with burned circuit board traces damage. Just a guess many were due to the user just installing new power tubes and 6922 tubes thinking they only needed to bias the power tubes. If you read the manual what would think?
Look no further than the OP of this thread.

For several years Upscale audio would not sell tubes to owners of ARC VT series power amps. Guys were blowing power tubes and damaging their amps and blaming it on the tubes Upscale audio sold them.

jea48

As a rule retubing an amp should not require sending it back to the factory or to a qualified manufacture service center.

Neither of these is a requirement for the VT-100, so I'm not sure what your point is.

ARC should have made mentioned in the owner manual retubing the 6922 tubes required they would have to biased.

Again, an owner's manual is not a service manual. They are two different things.

Thanks all for the input. I found a shop near me in New Haven CT that deals with ARC. I'm just going to take it in and have them take care of it. It will probable have to go to ARC. Thankfully the seller gave me a partial refund.

The best product hands down, first clean with 99% isopropyl alcohol
Craig make excellent small swabs. 
To protected long term over 10 years ,  and enhances tube socket conductivity 
As well as every thing  audio is  called Stabilant-22,   I have used many 
Many ,it is not messy has several applicators it comes with.
Check it out .it has been out for years even  NASA has been using it for years. 
Check it out.

Just a note the chances the bias will stay as set when shipped is slim as the vibration and knocking around during shipping will most likely change the bias a small amount so always better to do it locally with a reputable tech if the amp is not easily user biased. 

I chased a very similar noise for about a year on my tube pre-amp. Even replaced the tube sockets with gold plated versions. About $1,000 later it was ultimately a bad ground.  

Duder, did you switch tubes  switch channel's. 
 Is the cracking now comning from different 
Channel.  You should  Hope it is.