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Thread: tube position: horizontal or vertical

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    tube position: horizontal or vertical

    Greetings, would the position of the tubes in a chassis have any effect on tube rattle? I realize that the common position is vertical and at the back of the chassis, but if a tube, for some design reason was horisontal, would that increase the chances of tube rattle, or is that more in the over all architecture of the amp, and/or the proximity of the tubes to the speaker, and/or the brand of the tube?

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    In general, the common preamp tubes, 12A?7s run quieter horizontal. The other factors you list are usually greater, especially individual variations in tubes.

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    Really, thanks for that. I asked because I have recently purchased a Swart AST Master 112 combo. It's anew amp in their line. The story behind this version is that someone custom ordered a combo usi g the same platform that was used for the AST MkII head. So (I'm assuming here) rather than make up a whole new chassis for what seemed like one order, they just flipped the chassis from the head, putting the tubes in a horiziontal position, facing towards the front of the amp, above the speaker. Looking at the front of the amp, from right to left is rectifier, then power tubes (the amp is shipped with 6V6, but it will take EL34 or 6L6), then pre amp tubes. I'm not sure which ones are rattling, but one or several are. And, they are JJ's. The last time I used JJ's I had a Peavey Classic 30 and the tubes rattled in that amp.

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    Supporting Member Jazz P Bass's Avatar
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    Off Topic.
    I for one am really rooting for you Jared.
    You have been through the mill trying to find an amp that satisfies you.
    Hear is wishing you well & good luck in your search.

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    Haha! You got that right. This is my forth amp since December 2009. First one was a Peavey Classic 30 that just would not stop rattling (and it has a really crappy "2nd" channel), next was a PRRI that farts out really bad when the volume gets up to gigging levels, then was the Mesa LSS with unbelievable rectifier and fuse problems. I finally took that back to the store. I brought it in about a week ago to the shop where I bought it for them to look at it, and see if they couldn't figure out what was wrong with it. They had it for about four or five days, and at the end of the testing, they could find nothing wrong with it. The manager of the store knew about the problems, but was insistent that I had just had a bad run with tubes (3 5Y3's and one set of power tubes and about 6 fuses!!). He none the less suggested that I take it home for a few days to see what happens and if after that, if I don't want to keep it, he'll give me full store credit. So I get it home, and two days later, I'm playing for maybe 1.5 hours, I turn it off for a break, and then come back to about 1/2 hour later and pop! Blew a fuse! So I put the last one I had in, and pop, zip!! Blew the fuse and the 5Y3!!

    I called the store in the morning and said that I'm done with the amp. So I took it in and wondered around the store wondering what I could get for $2200~ in credit. There were no amps that I wanted from them. I ended up leaving with a gorgeous Gibson LP Traditional in Cherry Burst. No problems yet!!

    So yes, I now have the Swart AST Master. Amazing sound, but there is tube rattle!! I tend to think it's the JJs as the last time I had any problems with tube rattle they were JJs as well (in the C30). I called up thetubestore.com today and they said they have more problems with JJ's rattling than with Tung Sols or EH tubes. They also said that it likely wouldn't be the pre amp tubes, but the power tubes.

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    Last edited by Jared Purdy; 02-26-2011 at 06:23 PM. Reason: wrong date!!

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    Found a spare set of new JJ's in my basement. Guess what? No rattle! Hows that for product consistency!

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    Noodle of Reality Steve Conner's Avatar
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    So does this mean you finally have a trouble-free amp?

    Many famous amps mounted the tubes horizontally like that. The AC30, JTM45 and so on. Most smaller tubes are specified on the datasheet as OK for mounting in any orientation.

    A combo amp is a hard environment for tubes because of the extreme levels of vibration. No matter how they are mounted there's always a risk of rattles and microphonics. You can get rubber dampers for preamp tubes, but power tubes run too hot for them.

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    "Enzo, I see that you replied parasitic oscillations. Is that a hypothesis? Or is that your amazing metal band I should check out?"

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    I've seen on some tube rectifier data sheets that the tube prefers a particular orientation when mounted horizontally. I don't know if Swart obeyed these rules or not.

    I've never seen a preamp or power tube data sheet that I can remember, for any of the popular guitar amp tubes, that disallowed any mounting position.

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    Tube rattle is part of my "sound". Just kidding, but glad you're sorted.

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    Yes Steve, I think that I have finally nailed it!! I wasn't aware that those VOX and Marshall amps' tubes were horizontal. It was the first time I had seen it, and it looked odd to me. I was on thetubestore.com yesterday looking at the tube dampeners they have , teflon and titanium. Interesting. I'm going to leave it the way it is for now, and if no rattels, that's good for me!

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    Noodle of Reality Steve Conner's Avatar
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    Quote Originally Posted by Ken Moon View Post
    I've seen on some tube rectifier data sheets that the tube prefers a particular orientation when mounted horizontally. I don't know if Swart obeyed these rules or not.
    I think with directly heated rectifiers, they like the long axis of the anode box to be vertical, to reduce the chances of the filament sagging into the anode and blowing the tube up.

    The problem is that different manufacturers put the guts at different angles relative to the pins, so even if Swart got it right for the brand of rectifier he supplies, it's not guaranteed to be right for the replacement. With indirectly heated rectifiers it should be a non-issue. I wouldn't worry about preamp tubes, or short stubby power tubes like the 6L6 and 6V6.

    I've seen in the KT88 datasheet: If mounted horizontal, pins 4 and 8 should be in the same vertical line. But this is only a "recommendation". I always thought it was because of sagging grids, but in the Morgan Jones book, he says it's to get the hotter parts of the envelope at the sides for even cooling.

    Riz: I always wondered whether microphonics were responsible for some of the tube mojo.

    Jared: Great, glad to hear you finally got something solid, touch wood I always loved the look of the Swart amps, but have never heard one in person.

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    "Enzo, I see that you replied parasitic oscillations. Is that a hypothesis? Or is that your amazing metal band I should check out?"

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    Old Timer olddawg's Avatar
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    I have a homebuilt 18 watt Marshall clone chassis that I picked up second hand. It was originally in a combo but I mounted it in a headbox with all of the tubes laying horizontal since I was too lazy to remount the sockets. The amp sounds great, but I have noticed that as they get some use the EL84s rattle like a bitch.

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    I thought I'd just add to the discussion the fact that when tubes (especially power tubes & rectifiers) are in a horizontal position, they're more "vulnerable" to possible damage when the amp is being transported. Even HARDER on tubes (and reverb springs, when that pertains to your rig), is putting casters on a combo amp, and rolling it on hard surfaces.....TUBE KILLERS!!

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    Tubes in combos generally have a shorter life expectancy due to all the vibration. EL84s are especially vunerable. Treat them like strings.......change when its time.

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    Quote Originally Posted by Jared Purdy View Post
    Yes Steve, I think that I have finally nailed it!! I wasn't aware that those VOX and Marshall amps' tubes were horizontal. It was the first time I had seen it, and it looked odd to me. I was on thetubestore.com yesterday looking at the tube dampeners they have , teflon and titanium. Interesting. I'm going to leave it the way it is for now, and if no rattels, that's good for me!

    Before you spend rediculous money on dampers, go to a hardware store and check out some O rings of the proper diameter. Don't use the black ones. Use the red. The red "usually" will not melt. Worth a try for 20 cents apiece rather than 20 dollars or more for botique dampers which are frequently the same thing repackaged IMHO.

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    Speaking of Peavey Classic amps; ironically Peavey patented the construction where mounting axis of tubes and the speaker are in parallel to minimize microphonics. Guess it wasn't so effective after all...

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    PV classic lead ch

    [QUOTE=Jared Purdy;203720]Haha! You got that right. This is my forth amp since December 2009. First one was a Peavey Classic 30 that just would not stop rattling (and it has a really crappy "2nd" channel). I had a PV Classic50 for awhile in the 90s. Just did not work with my LP Jr. Then I played one later with a strat and it became clear the lead ch was designed for low output pickups. Worked great that way.

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    I built a Marshall 18w clone that still has the same tubes from when I built it over 15 years ago!

    Vintage Mullard preamp tubes and a pair of those EI EL84's from back when those were good.

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