Tubes 101....are you tube paranoid?

Wayner · « **on:** 18 Aug 2012, 06:54 pm »

Yesterday, I lost a tube in my AVA FET Valve preamp. I have never experienced a tube failure in this preamp before, so even for me, there was a learning curve and to be honest, a little nervousness.

This failure began earlier in the day, with sounds that seemed to waffle about in the low frequencies, yes the tubes were playing their own music, I guess. I was suspicious, but I really was eyeing up another component up stream (another tubed phono preamp). Then at about 4pm yesterday afternoon, in the middle of a record, it became distortion city.

I de-activated the phono preamp and went to Frank's SS phono stage built into my FET Valve. The results were the same. I confirmed this with the FM tuner, the preamp was to blame for this.

Normally, I would have just changed tubes, but this distortion was in both channels, and that usually points towards a power supply (or a rectifier tube as in the Ultravalve power amp, so I decided to give Frank a call.

He too, thought for a moment that I should send the unit in, but I did mention tubes as the culprit and he commented that the heaters are in series and 1 tube failure may show up in both channels, heard as distortion.

Sure enough, 10 minutes later and it was rock and roll again. The new tubes fixed the problem (there are only 2 tubes in the FET Valve.

Now there are some rules about using tubed equipment. One is that tubes are going to fail. We don't know when or why or how, but they will die. Rule 2 is to always have a complete set on hand when this happens.

Perhaps this is maybe for newbies or for those thinking about purchasing tubed equipment, and the truth is, perhaps tubes are not for everyone, but the fact is life does go on after a tube failure.

The important part is to recognize that there is a problem and take care of it. Tubes can last for decades or a day (or less), it's the nature of the beast. But do not let the fear of "tube death" keep you from enjoying great 2 channel sound.

Wayner

srb · « **Reply #1 on:** 18 Aug 2012, 07:27 pm »

Quote from: Wayner on 18 Aug 2012, 06:54 pm

One is that tubes are going to fail. We don't know when or why or how, but they will die. Rule 2 is to always have a complete set on hand when this happens.

Tubes can last for decades or a day (or less), it's the nature of the beast.

I brought this up in a past post relating to some Vincent Audio components, designed in Germany and manufactured in China. I had been offered a good deal on a few Vincent Audio hybrid components, but they used soldered-in tubes.

Even though they state the life of these small signal tubes is 15,000 hours, I couldn't ignore the fact that not every tube will last that long and there would have to be some premature failures. I didn't want to take the chance of being one of those unlucky owners.

Steve

bregez · « **Reply #2 on:** 18 Aug 2012, 07:27 pm »

I had a power tube (EH 6CA7) fail in my ST70 the other day. It was making some strange static sounds then some really loud white noise type sound with random pops and “crackling”, I looked over at the amp and the one tube was glowing bright red. I quickly turned off the amp. Which brings up another question, can tube failure potentially take out a speaker driver? Tube failure is a serious buzz kill; it is good to always keep a set of backups.
Brad

milford3 · « **Reply #3 on:** 18 Aug 2012, 07:45 pm »

Our old Philips TV with 14TX12OU/22 tubes. They (tubes) failed every six months or so. Tubes DO fail.

Wayner · « **Reply #4 on:** 18 Aug 2012, 07:47 pm »

Speaker Failure? Well, if you are playing distortion at high levels, I'm not sure what will happen. Personally, I think that tubes are kind to us all, in the fact that they certainly send us a message that something is wrong. If we ignore the message, things might escalate. However, there is good reason enough for me not to leave tubed equipment on 24/7 as many advocate. The good news is that Frank's equipment is designed to take advantage of the strengths of tubes, and the power of solid state as in the hybrid series of products (amps, preamps, DACs).

Wayner

SteveFord · « **Reply #5 on:** 18 Aug 2012, 08:02 pm »

Soldered in tubes seems like a real bad idea to me, too.
Makes it hard to tube roll, for one.
Every so often one will croak but I've never had one damage a speaker.
Whenever I see one of the threads about removing speaker fuses I always think of tube failure or stupidity on my part.

Wayner · « **Reply #6 on:** 18 Aug 2012, 08:16 pm »

Quote from: SteveFord on 18 Aug 2012, 08:02 pm

Soldered in tubes seems like a real bad idea to me, too.
Makes it hard to tube roll, for one.
Every so often one will croak but I've never had one damage a speaker.
Whenever I see one of the threads about removing speaker fuses I always think of tube failure or stupidity on my part.

Or changing to a higher then recommended fuse(s) in the amplifier......

Listens2tubes · « **Reply #7 on:** 18 Aug 2012, 10:57 pm »

I had a rectifier pop a fuse due to shorting. Took it out and it tested fine. Put it back in popped the fuse again. Went to a slo-blo fuse and watched the tube become a camera flash. I now use solid state rectification with a 30 second delay. Mainly because vintage Mullard 1959 wide base 5AR4's are super overpriced. Side benefit is tighter bass.

Devil Doc · « **Reply #8 on:** 19 Aug 2012, 12:16 am »

Thanks for the reminder. I've got to order some 6CG7s for my
first aid kit.

Doc

bregez · « **Reply #9 on:** 19 Aug 2012, 02:13 am »

Quote from: Wayner on 18 Aug 2012, 07:47 pm

Speaker Failure? Well, if you are playing distortion at high levels, I'm not sure what will happen.

When the power tube initiated failure it sent a loud crackle and pop to the speaker, I was just wondering if highly sensitive speakers would be susceptible to damage. At the time I was using some Dynaco A-25's whose drivers are somewhat robust (from what I am told).

Brad

SET Man · « **Reply #10 on:** 19 Aug 2012, 02:56 am »

Quote from: Wayner on 18 Aug 2012, 06:54 pm

.....

He too, thought for a moment that I should send the unit in, but I did mention tubes as the culprit and he commented that the heaters are in series and 1 tube failure may show up in both channels, heard as distortion.

......
Wayner

Hey!

Hmmm.... good point. I will keep that in mind

Take care,
Buddy

ArthurDent · « **Reply #11 on:** 19 Aug 2012, 04:26 am »

Quote from: SteveFord on 18 Aug 2012, 08:02 pm

Every so often one will croak but I've never had one damage a speaker.
Whenever I see one of the threads about removing speaker fuses I always think of tube failure or stupidity on my part.

A wise consideration from my pov. I've had (2) 6CG7 Mazdas fail in my T-8. The 1st maybe a month or so from installation, and thanks to Frank's guidance in tracking down the problem (post blowing fuses in both Dahlquist DCM-7s) I replaced it with another. 4 purchased originally. Then a couple of months ago, something around a year later maybe I experienced the same problem of channel dropout, then major static/distortion shot thru both channels. Sadly one of the problems for us less experienced tube folks is remembering past experiences. Again both speaker fuses blew, again I emailed Frank for advice and was easily guided to the problem ( as well as finally remembering the prior experience). So at this point I'm back to the OEM Sovtek 6N1Ps the unit came with. Not quite as warm as the 6CG7s, but less prone to failure. A similar experience was had by another here on AC who runs Frank's gear and purchased the tubes from the same source. Of course when my unit was purchased the Sovteks were stock, now due some chasis design revisions the 6CG7s are, though they are not the short ones like the Mazdas.

I need to get some backups from Frank at this point, as while I still have (2) of the Mazdas left, I hesitate to install them. Though I suppose there's not really any reason not to, let them fail and be done with it. I will say it hasn't deterred me from tube rolling, simply hasn't encouraged me either. I would support Steve's contention that removing speaker fuses may not be a good idea where tube gear is in play.

pmarun · « **Reply #12 on:** 19 Aug 2012, 04:44 am »

I bought a spare set when I bought my first tube amp 5yrs back, did some tube rolling and was thinking, maybe I didn't need those extra tubes. Looks like that is not the case. Everything going good so far, but good to know that I have my backup. Just in case.....

Wayner · « **Reply #13 on:** 19 Aug 2012, 11:48 am »

Quote from: bregez on 19 Aug 2012, 02:13 am

When the power tube initiated failure it sent a loud crackle and pop to the speaker, I was just wondering if highly sensitive speakers would be susceptible to damage. At the time I was using some Dynaco A-25's whose drivers are somewhat robust (from what I am told).

Brad

I run Dynaco A25XLs (modified) on my Ultravalve and experienced a 5AR4 failure, with no problems to the speakers. I think rectifier tubes like to fail at turn-on. I also always turn the volume completely off when I do fire things up, preamp first, then amp. I reverse this process at shutdown.

Wayner

rcag_ils · « **Reply #14 on:** 20 Aug 2012, 10:15 pm »

why were the tube heater wired in series, just curious.

Elizabeth · « **Reply #15 on:** 20 Aug 2012, 11:19 pm »

A comment from a tube paranoid person: me
I like the idea of tubes. And have an Audio Research Sp-15 with a three tube phono section. And a VAC Standard with four 12a(2u and 2x 7) tubes. But no tube amp for me.
I just do nto want to worry about tubes.
Then the cost. I can blow a fortune on stereo, but cringe over paying through the nose for tubes.
Now if i had a garagefull of NOs audio tubes i would be singing a totally diffrent tune.

Part of the issue is buying tubes is so fraught with issues.
The 'right' tube etc..

So it is as if tubes have marginalized themselves out of my experience.
Any over compartmentalized knowledge based. secret understanding guru/genius needed field is going to lose all non-crazy folks.
It certainly lost me. ((like Wine. WTF is all that different wine FOR in a grocery store??? I do not buy much wine, but one seems to need a damn PhD in 'Wine' to even find a bottle In a Supermarket!! for God's sake! without feeling like a moron))
If perhaps i had a person i could personally trust in tubes and such. But as it is it is a minefield IMO.
So this is one tube fearful person's confession.
I can manage a search for a few spare 12 AU7 or 12 AX7s.. but the rest? nope.
(( i also have a crazy SinglePower MPX3 headamp with a half dozen adapters and various tubes to toy with. It sits in the closet. Too much to contemplate. I use my Rudistor RPX33 SS headamp. WAY easier. never confusing.
So this is a message from the other side of tubedome.
It seems inviting. But then all the info overload just gets scary.

simon wagstaff · « **Reply #16 on:** 21 Aug 2012, 12:53 pm »

I have had a three tube failures in my U70. The first two were quite spectacular, sparks and glowing and stuff.

The last one just occurred a few days ago and was quite different. I had been feeling disappointed in the sound of my system. couldn't really put my finger on it. More distortion, things didn't sound clean. I messed with a bunch of stuff and then noticed that one of the new supposedly super chinese gold tubes I had just gotten wasn't lighting up, nothing going through it. it was sort of weird that there is a totally dead tube in one of the sockets and I still got sound. Have sent it back for a replacement, but I am not impressed by these super gold chinese tubes.

bunky · « **Reply #17 on:** 21 Aug 2012, 01:31 pm »

Tubes dont last forever nor do the tires brakes and shock absorbers on your vehicle.i dont get paranoid over tube failure but i always carry spares.

eclein · « **Reply #18 on:** 21 Aug 2012, 02:43 pm »

The last tube integrated I had (wasn't a Van Alstine) got extremely warm and I eventually traded it away because it worried me that I'd fall asleep or accidentally leave it on when out somewhere and start a fire. The manufacturer and folks I trust told me it was ok and I just never got comfortable with it, ended up it was an issue that hadn't come to light yet and some were melting or leaking goo so my paranoia was real.

The last year or so I've been running solid state amplification and tubes in a pre but I'll have another soon as the sound is just my favorite. My problem is cost of the initial unit as they are a bit more most of the time. I just gotta save up for another and I will!!

Wayner · « **Reply #19 on:** 21 Aug 2012, 07:26 pm »

Frank's FET Valve amps can take the worry out of owning a tube amplifier. It is a hybrid, using MOSFET output transistors for awesome power and control, and using tubes to effectively amplify small signals. Tubes in the hybrid amps will last for years, as they don't see any real loads.

Frank also has the new Synergy line of SS amps, for the tube sound lover, without the tubes. These amps are getting really good reviews, are certainly low in cost compared to other comparable amps and with the double die option ($99), can handle virtually any speaker made.

Wayner