Have you ever heard of an amp fail like this?

geowak · « **on:** 14 Nov 2015, 05:27 pm »

Just had a integrated tube amp fixed recently. The repairman stated that I must have put in a bad tube since the wiring was fried under the tube socket and it caused a complete transformer to fry.

I have been using some RCA, GE and Sylvania NOS tubes without any problem before, now I will be very wary of using them. The ones I tend to get are the military NOS versions of 12AX7, such as the 12AX7A or 12AX7WA. Also have used some NOS 12BH7A.

The companies/tubes I have used are Sylvania JAN 12AX7A, GE 5751, GE 12AX7A 7025, Sylvania 12BH7A.

Has anyone ever experienced a tube failure that resulted in a blown transformer? Also any problems with any of these NOS tubes listed? Right now one of the old Sylvania tubes are the ones I suspect as the culprit.

DaveC113 · « **Reply #1 on:** 14 Nov 2015, 05:31 pm »

Yes, I had a preamp's PT fail some years ago. It was one of the dual-chassis Anthem Pre-1s and it wasn't very reliable so I just sold it to PCX. I had to fix it twice before, after the PT went I gave up on it.

This can be an issue with tube gear, tubes can fail... but you're better off with NOS tubes than current production imo. Not all SS gear is reliable either, I had NAD amplifiers that failed on me (and lots of other people!) before.

Mark Korda · « **Reply #2 on:** 14 Nov 2015, 07:26 pm »

Hi Geowac, this may be a stupid question but were your speakers hooked up during any tube switching? I read your question and looked in this tube amp book under transformers. Without a lot of whys, the last sentence said operating an amp without a resistive load, your hooked up speakers, it is common to see the amp eat many power tubes as well, prior to transformer damage.......just something to check on the list I guess...take care......Mark Korda

SteveFord · « **Reply #3 on:** 14 Nov 2015, 07:58 pm »

Geowak,
You'd better get a tube tester and check for shorts before you stick one in there.
A tube from any manufacturer can be bad and things can get bounced into garbage during shipping.

pehare · « **Reply #4 on:** 14 Nov 2015, 10:41 pm »

usually it's an output/power tube that might cause that problem if the amp isn't fused like audio research amps...strange that a driver/pre 12ax7 would do such damage...what brand/model amp is it?

geowak · « **Reply #5 on:** 15 Nov 2015, 01:24 am »

Well thanks all... for the response. The speakers were connected. The amp is fused, it also is a PTP amp. Since the company is replacing the transformer they are just charging me for the time to rewire and put in a new tranny (plus shipping both ways). I think that is great customer service. I have a friend who has a tube tester, so every tube will be tested going forward.

Since I am thinking it was a tube, not the company I will not mention the name. I don't want to damage the rep of the manufacturer, since they are standing by the gear.

mlundy57 · « **Reply #6 on:** 19 Nov 2015, 06:42 pm »

Quote from: geowak on 15 Nov 2015, 01:24 am

Since I am thinking it was a tube, not the company I will not mention the name. I don't want to damage the rep of the manufacturer, since they are standing by the gear.

Actually, I consider it a big plus when a company stands behind it's products and letting people know who it is is a testament to the company's integrity. Problems are inevitable for any manufacturer. How they deal with it is what sets some apart from the others.

Mike

rollo · « **Reply #7 on:** 19 Nov 2015, 06:48 pm »

Quote from: geowak on 14 Nov 2015, 05:27 pm

Just had a integrated tube amp fixed recently. The repairman stated that I must have put in a bad tube since the wiring was fried under the tube socket and it caused a complete transformer to fry.

I have been using some RCA, GE and Sylvania NOS tubes without any problem before, now I will be very wary of using them. The ones I tend to get are the military NOS versions of 12AX7, such as the 12AX7A or 12AX7WA. Also have used some NOS 12BH7A.

The companies/tubes I have used are Sylvania JAN 12AX7A, GE 5751, GE 12AX7A 7025, Sylvania 12BH7A.

Has anyone ever experienced a tube failure that resulted in a blown transformer? Also any problems with any of these NOS tubes listed? Right now one of the old Sylvania tubes are the ones I suspect as the culprit.

Yes my Consonance 211 amps were toasted [ one] when the 211 failed. The wax in the trannie melted. Consonance stood by and supplied me with all new parts for their cost.
Today still sounding great however now use hybrid class "D".

charles