tube paranoia

[redgibson]

So my band has a gig playing a wedding coming up and I keep having this thought in the back of my mind... my tube amp is working great, no problems. (HRDx) But... what are people's experiences travelling / gigging with tube amps? Should I get a backup set of tubes to be prepared just in case? Power tubes? Rectifier? Both? I just want to be prepared as possible in case the crap hits the fan ampwise... aside from having 2 amps. (go solid state?? um... I would be hard sold but open to suggestions...) Whats the deal folks? :-) Looking forward to turning it up to a decent volume level for a change in a big hall (200 people at the wedding!)

[deeaa*]

I always keep a single preamp tube in my gear case. They very seldom just blow, but sometimes the tremors and such of traveling may be the last straw and you notice some ugly buzz or something, and then it's good to have a spare tube at hand. I've changed a preamp tube 2-3 times just before a gig for said reason - they would have worked but some buzz or something.

As for power tubes...I don't know, in my experience they go bad slowly OR they blow catastrophically - in either case a spare wouldn't help much. You usually need to bias power tubes anyway. So if they sound fine and seem fine, they probably are for a while still. And if they suddenly blow, well, they'll probably do so because the OT blew and a spare wouldn't help.

In general, I trust a basic tube amp a lot farther than an SS job. Hardly ever meet SS amps more than 10 or so years old and working fine, whereas simple toob amps can be 20-30 years no problem whatsoever.

I used to never have a backup amp till the final years of my active gigging, which is when I started carrying along a Tech-21 Tri-AC pedal that I could have plugged straight to PA instead and have 3 ok sounds to play with.

SO I would recommend one preamp tube and possibly some suitable pedal or gadget that would make it possible for you to play everything D/I - not as good but just enough to get by.

Funny story: on one gig I somehow broke my channel switch on my Fender Twin once, and played the entire (rock-heavy) gig with basically a clean sound. Hardly ever have I gotten such good comments on how damned good my guitar sounded the entire gig - simply because I could not use distortion channel at all, or any other effects built on that. Just played a li'l crunchy clean all the way thru and even for hardrock it finally worked better than my elaborate drive channel settings ever did, for the audience that is. I myself found it really hard to play metal riffs with a clean sound....

...in the end the audience doesn't much care what you sound like as long as they hear you OK.

[Eric***]

Funny story: on one gig I somehow broke my channel switch on my Fender Twin once, and played the entire (rock-heavy) gig with basically a clean sound. Hardly ever have I gotten such good comments on how damned good my guitar sounded the entire gig - simply because I could not use distortion channel at all, or any other effects built on that. Just played a li'l crunchy clean all the way thru and even for hardrock it finally worked better than my elaborate drive channel settings ever did, for the audience that is. I myself found it really hard to play metal riffs with a clean sound....

...in the end the audience doesn't much care what you sound like as long as they hear you OK.

That's pretty funny, and that last sentence seems like signature material.

[tunghaichuan***]

So my band has a gig playing a wedding coming up and I keep having this thought in the back of my mind... my tube amp is working great, no problems. (HRDx) But... what are people's experiences travelling / gigging with tube amps? Should I get a backup set of tubes to be prepared just in case? Power tubes? Rectifier? Both? I just want to be prepared as possible in case the crap hits the fan ampwise... aside from having 2 amps. (go solid state?? um... I would be hard sold but open to suggestions...) Whats the deal folks? :-) Looking forward to turning it up to a decent volume level for a change in a big hall (200 people at the wedding!)

It is a good idea to have a spare set of tubes on hand. You don't need a rectifier tube as the Hot Rod Deluxe has solid state rectifiers. You would need a spare set of power tubes and preamp tubes. It also might be a good idea to get a bias measuring tool. This plugs into the amp so that you can rebias the amp. Of course if you're performing, you may just want to replace the tubes and wing it. The only downside is that if you have tube failure, it may not be the tubes that caused it and plugging in a brand new set might damage the tubes, or the amp, depending on what is wrong with it.

[Bloozcat]

I could make an arguement for a spare set of tubes or for a backup amp.

If I was playing through my 65 Band Master head, the most I'd be worried about is probably just a pre-amp tube, or worst case, a speaker. But, the Band Master is a direct wired eyelet board circuirt, not a printed circuit board. I've had a circuit board tube amp go wonky in the middle of a song before, and it wasn't the tubes, it was the circuit board. Happened to my friend with a normally reliable Peavey Classic 50 2-12 as well.

In reality you can only worry about so many things. A spare set of tubes and/or a backup amp, and you're probably covered. But, weird things can always happen, no matter how remote the chance.

[kiteman]

How about taking the tubes out before shuffling the amps around?

Just a thought.

[redgibson]

Good feedback everyone , thanks- I forgot it didn't have a tube rectifier. I liked the idea of the direct box (like a sansamp or something) in case of emergency straight to the PA. Spare set of tubes is probably a good investment as well. I thought if you bought a matched pair of tubes that match the color on the groove tubes already in your amp you're good to go sans-biasing?

One more thing I noticed- i read blue color in the tubes means they're underpowered. I never thought to look or notice before, I played over lunch and they were... predominantly blue glow with amber in the bottom of the tube. Do they ship underpowered or should i not worry about it or check it after an hour of serious playing at serious volume?

[tunghaichuan***]

Good feedback everyone , thanks- I forgot it didn't have a tube rectifier. I liked the idea of the direct box (like a sansamp or something) in case of emergency straight to the PA. Spare set of tubes is probably a good investment as well. I thought if you bought a matched pair of tubes that match the color on the groove tubes already in your amp you're good to go sans-biasing?

The preamp tubes are cathode biased (self biasing). Your Hot Rod Deluxe is a fixed bias amp. I'm not sure if it user adjustable or not. Some fixed-biased amps have a bias adjustment pot built into the circuit.

Cathode biased amps for the most part don't need to have the bias changed when the tubes are changed, although it is a good idea.

But since your amp is fixed bias, you should have the bias adjusted every time you change power tubes.

One more thing I noticed- i read blue color in the tubes means they're underpowered. I never thought to look or notice before, I played over lunch and they were... predominantly blue glow with amber in the bottom of the tube. Do they ship underpowered or should i not worry about it or check it after an hour of serious playing at serious volume?

The only color you need to worry about is cherry red. If the anodes in your tubes (metal part in the center) start to glow cherry red you either don't have enough negative bias voltage or none at all. When this happens your tubes are probably not going to live much longer.

You don't need to worry about blue glow in tubes:

http://www.jacmusic.com/html/article...w/blueglow.htm

http://thetubestore.com/blueglow.html

http://www.netads.com/~meo/Guitar/Tubes/blue_glow.html

[oldguy]

Your Hot Rod Deluxe is a fixed bias amp. I'm not sure if it adjustable or not.

But since your amp is fixed bias, you should have the bias adjusted every time you change power tubes.

That seems confusing somehow.......

[kiteman]

That seems confusing somehow.......

I think he means resistor wise. You can change resistors to change the bias.

[tunghaichuan***]

I think he means resistor wise. You can change resistors to change the bias.

Kiteman is correct. In a fixed bias circuit there can either be a resistor which sets the negative bias voltage to a predetermined level or there can be a pot which can be adjusted within a certain range. These days, the resistor needs to be changed or the pot needs to be adjusted every time the tubes are changed out. Back in the good old days when tubes were manufactured in the West, it was not as critical. RCA/GE/Sylvania/Tung-sol/et al. made tubes to very tight tolerances and very strict quality control. Nowadays, not so much.

Also, as tubes age, their bias voltage requirements change as well.

In a cathode bias circuit, there is also a resistor, from the power tube(s) cathode(s) to ground. This circuit is self adjusting, so it is not as critical to reset the bias every time tubes are changed out. However, I usually like to check it anyway just to make sure the tube isn't dissipating too much power.

Sorry for being unclear.

[tunghaichuan***]

That seems confusing somehow.......

Sorry Oldguy, I meant user adjustable. Fixed in my post.

[oldguy]

Thanks for explaining, Tung, that makes it easy to understand!

[redgibson]

I think I need to sit down with a "Tube Amps Explained" book or something. This is all very good information I just don't quite understand half of it. I like the way they sound / react! Now I have to figure out how they work. Thank you everyone. BTW, the wedding went great without a hitch. Packed the dance floor and got a cheering rowdy crowd. It was a great confidence booster :-)

[otaypanky***]

A spare set or power tubes and a pre amp tube are good things to keep in your gear kit. If it's an important gig I'd tote along a small amp as a spare. You can always mic it.
Just a suggestion regarding the volume going up since you'll be playing in a big hall ~
I'd suggest you keep it just like you always do, maybe even lower, but certainly not louder. People are going to attend the wedding and reception, you just happen to be there. Folks will want to talk and catch up with old friends and family. I suspect there will be people there of varying ages. Older folks may not have such good hearing. There's nothing more boring than sitting around a big table staring at people and not being able to have a conversation because it's too loud. I heard B.B. say in an interview something like "If you're shouting at someone it doesn't take long before they stop listening. But if you whisper something to them, they'll lean in to hear what you're saying."
Intensity without the volume is powerful. Anyway, just my 2 cents.
'Hope it all goes well and have fun

[ZMAN]

I would say that if you are getting paid for these gigs, it would only make sense to have a back up amp. By the time you got around to finding and fixing the tubes, you would have pissed off just about everyone at the gig.
Especially a wedding. You wouldn't have to pay a lot for one just have one that would plug in and go all the time. Maybe a solid state. You might lose some on the tone but it would rescue the evening.
There are a ton of really nice SS amps with the equivalent of a 40 watt tube amp, that could model as well.

[redgibson]

ZMAN you're probably right on. Maybe a roland cube 60 or something just to get by. i guess a backup is not your ideal amp scenario its a shit hit the fan! scenario. Something's better than nothing :-) I'll hunt around. but I'll carry some tubes as well. Accruing lots of GEAR... my spine!

[Duffy]

Roland has the cube 80 now. Also Fender Super Champ XD is equal to approx 45 ss watts volume stock, more w the ragin' cajun speaker. Also Peavey Bandit.

[TradAmpGuy]

A few points. Extra tubes are always a good idea. Dont worry about taking the tubes out when traveling, tubes are a lot more rugged than people give them credit for. Heck they were bouncing around in the backs of cars since rock and roll went on the road One caveat though, they dont like to be bounced around when hot, let them cool down at the end of the night before you start loading them in the car/truck. Also, dont forget some spare fuses. While a fuse blowing usually means that there is something wrong more than a bad fuse, sometimes they do just blow.

The HRDx is a fixed bias amp and it does have a pot for adjustment. I've done a few of them. If you do go the Groove tube rating method and keep buying the same rating tubes remember, tubes change over time. If you get the same rating tube it should work fine as long as the bias hasnt been adjusted to an older set. In that vein, the bias should be checked/adjusted every year or two so depending on how often you use the amp so that you get the best tone from your tubes. A good cleaning at that time wouldnt be a bad idea either. I did a tube swap on a HRDx that had the original tubes and it was idling at only 20mA/tube. The amp sounded brittle and harsh. Put in a new set of JJs and set the bias at 35mA, cleaned it up (pots, jacks, sockets) and it sounded real nice. Fender BTW recommends 30mA per tube which still sounds a bit cold to me.

As far as a good read on tube amps I liked "The Guitar Amp Handbook" by Dave Hunter.