freestompboxes.org

Just skimmed your latest comments but if the tubes are not oscillating, don't worry about it. All tubes are microphonic to a point and will make noise if you tap on them. The question is whether they are so bad that they start squealing on their own due to the normal vibrations of playing.

I agree with previous posts. Let your tube guy check it over and if he recommends replacing tubes, then let him recommend what tubes to use.

deltafred wrote:Difficult one that.

You checked the amp out before you brought it home so I suspect you might struggle to get Ebay to support a claim. If it were a new amp I would have thought that you might have had a better chance but a used amp is just that and subject to fair wear and tear. Depreciated valves would probably be classed as fair wear and tear.

Well, I decided to give the guy a call since I had his number from picking it up. I told him about the valves, and just asked if there was anything we could work out in a very friendly way. I explained that I thought he seemed a genuine guy, and I was sure that he didn't realise there was a problem. He was saddened to hear that the valves were microphonic and said he had never realised. He told me that he had already spent the money I gave him on a new amp, but that the guy selling his new amp was providing a new set of EL34's along with the ones that are already in there and he could post those to me as he wouldn't need them. So, that is that sorted I guess. I wonder what they will be?

biliousfrog wrote:I used to use HotRox but Watford have a better selection and worked out cheaper.

I used to use Watford Valves, but I always found them to be considerably more expensive. I started using HotRox because they had a reasonable selection, and seemed to be cheaper (needs must unfortunately). I agree with you about the service though.. I did miss the advice from Watford Valves. Maybe it's worth a look back there again, I haven't been on their site in a few years.

phibes wrote:Lets put it this way, my Fender Blackface Bandmaster still has the original preamp tubes running and she was born in the late 60's.

Have you got any opinions from the amp guy at all? I'd just let him pick the valves if he's gonna be working on it. I'm sure he'll have a recommendation and fav to work with.

That's incredible.. are valves made to be as durable these days? Is what musicians are told - replace your valves every two years - just to keep the money rolling in? All the contradicting information you find on the internet is enough to make your head spin.

I haven't spoken to my amp guy yet, I was thinking of giving him a call today for a chat and organising when I can drop it off to him. Normally he has you supply the valves, he only goes ahead and replaces components with his preferred choice usually. But, I'll speak to him first and see what he thinks.

DougH wrote:Just skimmed your latest comments but if the tubes are not oscillating, don't worry about it. All tubes are microphonic to a point and will make noise if you tap on them. The question is whether they are so bad that they start squealing on their own due to the normal vibrations of playing.

Well, yesterday when I was cranking it up a little.. I could hear some subtle oscillation, barely noticeable, but it was there. I could hear the valves popping a little too.. I think they have had it. How he didn't notice this, I don't know. This was only after about an hours playing. Later that night I turned it back on to see if it was present, but nothing. So I guess they must be teetering on the edge.

I would think that the guy you bought it from had no idea that any valves were microphonic, in normal use they have to be pretty bad before they become apparent (tapping them with pencils is probably not classed as normal use ).

I use Watford Valves for customer amps because I require a fast service and some come back if there are any problems. (Watford are FAST and I have never needed to return anything.)

For my own I have a pile of old stock/junk, mostly used that I hunt through until I find something suitable.

sickman82 wrote:

phibes wrote:Lets put it this way, my Fender Blackface Bandmaster still has the original preamp tubes running and she was born in the late 60's.

That's incredible.. are valves made to be as durable these days? Is what musicians are told - replace your valves every two years - just to keep the money rolling in? All the contradicting information you find on the internet is enough to make your head spin.

Musicians are told to replace their valves every two years meaning their POWER valves. Its probably an added bonus to the tech if they want the whole thing, even though they dont need to replace their preamp valves. Power valves will go in a year or two if played a lot. Preamps, even played a lot, can and will last decades.

Tube life is all relative. Heat kills tubes. Power tubes see a lot more heat and wear and tear than preamp tubes.

If you have a high-wattage amp and keep it turned down to occasionally practice, you can get 5-10 years out of a set of power tubes. A touring pro who cranks his amps 4-5 nights a week might go through a set in 6 months. New production tubes are not nearly as robust as the way they used to be made...there was a time when all radios, TV's, stereos, PA systems, theater sound systems, etc. use tubes and there were a household item. Companies like RCA and Philips made and sold tubes because they made and sold what tubes went into. There was a lot more money to be made on tubes and a more care put into making them. Now they are an obsolete product made for a hobbyist market. A good quality RCA or Mullard could outlast a modern tube by 3 or 4 times as long.

As to micro-phonics..all tubes will make a thud when tapped with a pencil...the thud isn't the test. A microphonic tube as parts that have come loose and vibrate against one another, causing the tube to oscillate and squeal. So, when tapping with the pencil eraser, a "thud" is normal, feedback and squealing is the symptom of microphonics.

well a light tap shouldn't have an easily audible thud, I don't think. I have not found that to be the case at least.

Sometimes if you tap a 12AX7 that's operating at a high gain with a pencil, they will make a "pong" sound, if it is followed by a high-frequency ringing sound or squeal, then that's a sure sign that the valve/tube is microphonic and needs to be changed with a good one, some valve/tubes are more microphonic than others.......

i'm having a pretty good experience with the GT EL34s in my home cooked JCM800.
clean and very detailed.
winged C are praised all over the internet.i never heard them so i can't comment.

I have used a heap of Winged C EL34's in my repair workshop over the last 10 years or so. They were consistently reliable and always sounded great when correctly burned in and biased.

Sadly, they have been bought out (by Sovtek I think) about 18 months ago and the current production EL34s have higher failure rates, inconsistent gain and tonality and show all the signs of poor quality control.

The Chinese Shuguang EL34's are much cheaper, more reliable (except in circuits where the B+ supply exceeds 450vDC) and sound good.

Never thought I'd be recommending Shuguang EL34s over Winged C. Sad days indeed.

blackbunny wrote:I have used a heap of Winged C EL34's in my repair workshop over the last 10 years or so. They were consistently reliable and always sounded great when correctly burned in and biased.

Sadly, they have been bought out (by Sovtek I think) about 18 months ago and the current production EL34s have higher failure rates, inconsistent gain and tonality and show all the signs of poor quality control.

The Chinese Shuguang EL34's are much cheaper, more reliable (except in circuits where the B+ supply exceeds 450vDC) and sound good.

Never thought I'd be recommending Shuguang EL34s over Winged C. Sad days indeed.

SED wasn't bought out, they were phasing out their consumer audio tubes. Some people in St. Petersburg have said they actually quit making them some time ago and have just been selling off a back stock. My guess is the last several rounds were rushed out to build that back stock before they shut down the machinery for good.

wyatt wrote:SED wasn't bought out, they were phasing out their consumer audio tubes. Some people in St. Petersburg have said they actually quit making them some time ago and have just been selling off a back stock. My guess is the last several rounds were rushed out to build that back stock before they shut down the machinery for good.

Bad news for EL34 lovers. Maybe the poor quality control was caused by someone selling off a large quantity of Winged C valves / tubes that had been rejected by QC over the years!

There seems to be a new range of Svetlana and some Winged C audio valves / tubes on the market here in Australia. Has someone bought the rights to the brands?

blackbunny wrote:

wyatt wrote:SED wasn't bought out, they were phasing out their consumer audio tubes. Some people in St. Petersburg have said they actually quit making them some time ago and have just been selling off a back stock. My guess is the last several rounds were rushed out to build that back stock before they shut down the machinery for good.

Bad news for EL34 lovers. Maybe the poor quality control was caused by someone selling off a large quantity of Winged C valves / tubes that had been rejected by QC over the years!

There seems to be a new range of Svetlana and some Winged C audio valves / tubes on the market here in Australia. Has someone bought the rights to the brands?

Not sure about Oceania, but in the North America, it's been confusing since 2001 when the company's competitor New Sensor took control of the U.S. trademark on the name Svetlana. You can read about it here.

http://www.stereophile.com/news/022304svetlana/

IIRC, the original American importer for JSC Svetlana/St. Petersburg was disgruntled because they lost the rights to CE Distributing (Antique Electronic Supply's wholesale side), so they sold the trademark, and all the brand equity the Svetlana had built, to New Sensor (Sovtek/Electro-Harmonix/etc.), who then traded on that brand equity to sell their own Svetlana-branded tubes.

This is why the real St. Petersburg tubes became known by their "Winged C" logos in the first place.