Hiss in T7 on power-up

Ron S · « **on:** 29 Jan 2005, 05:21 am »

Hi all!

Been a while since I frequented this forum, but only because I've been so happy with the performance of my T7 working with my Odyssey Extreme Monos and RM40's.

About a month or so ago, I noticed a significant (LOUD) hiss when turning on the T7, but it lasted only a few seconds. Lately, the duration of the hiss is getting longer, lasting almost 30 seconds! (guesstimate-seems like forever). Is there a known issue that could cause this?

Aside from having to get up off my keester to turn on the dang thing, I'm in love with the sound that the T7 gives me.

Any ideas would be welcome...

Ron

Dan Kolton · « **Reply #1 on:** 29 Jan 2005, 02:41 pm »

Ron,
The best idea I can think of is to call or e-mail Frank VanAlstine. I'm sure he can help you. I agree with your evaluation of the T7. I love mine too!

jackman · « **Reply #2 on:** 29 Jan 2005, 04:30 pm »

It sounds like you have a bad tube or a tube ready to go. Mine is totally silent at all times and sounds great like yours. Are you using original tubes? I tried some NOS tubes and some were noisy. Swapped back the originals and they sounded great again.

Good luck, Frank will take care of your question, I'm sure.

J

avahifi · « **Reply #3 on:** 30 Jan 2005, 05:43 pm »

Is it a one channel or two channel problem? If a one channel noise then with the unit turned off, swap the line tubes from channel to channel and see if the hiss follows a tube. If not, call me at 651-330-9871 for more help.

Frank Van Alstine

Ron S · « **Reply #4 on:** 6 Feb 2005, 02:08 am »

Hi Frank,

To my surprise (kudos to your knowledge of your product), it *is* a one channel problem. It's only coming from the right side. I never noticed it because I tend to sit on the right side while watching TV. Not only that, but after further investigation, I notice a low level hiss *all* the time if I put my ear up close to it.

I'm very unfamiliar with the inner workings of the T7, though. Knowing what we now know, is it useful to try and switch tubes, or is a replacement needed? In either case, is there some sort of schematic on your website that can walk me through it?

Thanks for your help...

Ron

jackman · « **Reply #5 on:** 6 Feb 2005, 04:48 am »

Ron,
It's very easy to swap tubes, just unscrew all of the screws holding on the metal top of the unit and remove the tubes and swap them or switch the right for left. If the sound comes from the other side, it's the tubes. Just don't poke around with the unit while it's plugged in> Also, VERY IMPORTANT, make sure the unit is unplugged when you swap tubes. If you are in Chicago, I can help you out. Just let me know. Tubes are cheap also. If it is a tube, a replacement is less then $15 and they last a very long time.

J

Ron S · « **Reply #6 on:** 25 Feb 2005, 11:01 pm »

Ok, got my new TV today, so had things moving around in the rack. Took the opportunity to open the T7 and switch the tubes...

First, OMG! Frank, could you *put* any more screws on the thing? (Best Chandler Bing imitation).?

Second, the hiss definately follows the tube, now on the left side. How do I order a replacement? Also, I recall some people saying there were different tubes available in posts of yore. Is there a possibility that a different tube than the stock one would provide an increase in performance?

Thanks for the help, guys! On my way to getting it fixed, yay! Err, forgot about all those screws I'll need to redo

jackman · « **Reply #7 on:** 25 Feb 2005, 11:03 pm »

AVA has tubes at a good price. I like the stock tubes best. Bought several NOS ones at various price points but kept coming back to the originals. Just my opinion, but I'd stick to the original variety.

I suspected it was the tube. I had a tube go bad about a year ago. It happens. Luckily they are cheap and easy to replace (if you have a power screwdriver!).

J

dave1010 · « **Reply #8 on:** 16 Sep 2005, 01:53 pm »

I would use the original tubes, and then play with other tubes with the J.J. as a reference. Also, be careful about fingerprints all over the tubes, I hear they hate that! [/list]

markC · « **Reply #9 on:** 16 Sep 2005, 08:45 pm »

Just in case you were not already planning on doing so, I'd definatley replace both tubes, not just the faulty one. Since they're cheap enough, no sense running one old and one new. The non faulty tube will likely fail soon enough. Tubes are not like semi-conductors-they do wear out. Oh, and as I'm sure you know, they don't sound like semi-conductors either.

avahifi · « **Reply #10 on:** 18 Sep 2005, 01:37 pm »

If you choose to replace a pair of tubes, remember to keep the good old one as a spare.

Right now a set of two JJ Electronic 12AT7/ECC81 or 12AX7/ECC83 tubes are available from us for $29 plus $8 shipping and handling in the continental USA. Specify which tube type you need.

Frank Van Alstine