The Steel Guitar Forum

Not sure this is the place for this question, but here goes. I've had this amp for a few years, and never had any issues until today when I noticed that one of the power tubes was not working. My question is, do I need to replace all of them or just two? It is the far most outside tube on the left looking from behind the amp. The reverb channel works fine, not sure about channel one.

BTW, I'm new to the site and to the steel, and I'm finding it hard to really dial in the settings. I can dial it in most of time pretty good for my ear with my tele and LP, but with the sho-bud it's been a little tough. Any help would be greatly appreciated.

Marty

Get a tester, or bring them to someone who can test them for you.
Having a tube amp requires a bit more maintenance in this regard,
and good tubes can make a substantial difference in sound.
You'll find that there is a difference in price too and if you're lucky,
you get what you pay for.
NOS (New Old Stock) tubes from companies like RCA and others
are in high demand because they sound better than many made today.
Usually getting a matched pair is better than replacing one, but Im no expert.

The 65 RI may be a bit hard to get good steel tone from sometimes, as its designed primarily for guitar.
Of course if you need to replace tubes, that will make it harder to get a decent sound, period.
Try b0bs method: turn bass full and treble and mids off, then while playing,
add treble and/or mid a little at a time till you find something pleasing.
You'll notice the relationship of bass and volume, so as you turn up the volume, lower the bass a little.

Clete

I've heard of a number of DRRI amps having tube failures ("Hey, just one tube is glowing!") that took out the screen resistor. Those resistors -- one for each 6V6 power tube -- are 470-ohm/1W and they really should be 1K-ohm/5W so that if a tube fails it won't turn its respective screen resistor to toast. It could be that you had a tube failure or maybe those chintzy power tube socket pins need re-tensioning. I had to re-tension those pins a couple of times before a complete re-build (I'm not a big fan of the components and the PCB construction in general, for Fender reissues).

Also, I think sometimes people rock the power tubes back and forth (side-to-side) a bit too much when changing them, and over time this can loosen the socket pins. Even though I'm pretty careful, I now have very solid NOS sockets and worry less about pin tension issues. You'd also be surprised at the variance of power tube pin diameters (new manufacture versus NOS vintage, especially the early JJ 6V6 tubes, but later ones are better). Here's a good thread on how to re-tension socket pins. Remember: there's a TON o' juice that can fry you good, so be careful. http://www.fenderforum.com/forum.html?d ... ber=571400

I had a failure of one EH 6V6 which took out its respective screen resistor which I then replaced with the same stock value. Soon after, I ended up getting rid of that stock circuit board -- I had Ben Fargen do a complete re-build which made this an awesome amp ... a real mid-60's vintage DR Killer -- so I never upgraded the screen resistors, myself, as referenced above.

If you've had a tube failure, check out this schematic/layout page that shows R62 and R63 -- you'll see the screen resistors across from the Fender logo on the circuit board part of this page.
http://support.fender.com/schematics/gu ... ematic.pdf
If I had to guess, I suspect you've had a tube failure ... it's just a matter of whether it took out that screen resistor on its way out the door. ("Come with me to the Land of Toasted Components!").

If the screen resistor for that power tube is not toast, you can just replace your power tubes -- and I would replace both tubes. (And get good ones). You don't want to just pop in another unmatched tube (buy 'em in pairs or measure your tubes for almost the same -- within 5% -- of current draw). Otherwise you won't get the best tone and you may even have a substantial problem with hum. So buy 'em as a duet from a reputable seller.

I prefer NOS (RCA) but I realize those are expensive. I don't like the EH because of my own experience and other reports of numerous failures with them; the failure rate may be somewhat less in more recent days. If you're using your DRRI for steel I'd recommend using the JJ 6V6 because it's really more like a small 6L6 (tonally speaking) and you'll get better headroom; as a bonus, they are bomb-proof and hard to kill -- they can take insane bias settings (ie: current draw in mA). You'd have to re-bias JJ 6V6 tubes because they'll be too cold if you just pop 'em in, using the bias setting from the factory, if replacing stock factory-supplied power tubes. I think it's good for anyone with a tube amp to have a decent bias measurement tool because you can tweak your tone to your heart's content. (My DR is approx. 62-65% of max plate dissapation, not as cool as some like, but not as warm as some other preferences).

For steel, you want a "harder" set -- later break-up, for max headroom. Also, for steel, the DRRI benefits from having a speaker with a higher wattage rating (the stock Jensen, for instance) but other 50-100W speaker choices from other makers sound a bit better; a speaker choice that has an ever-so-softened high-end response may be better for this amp that has the non-switchable bright cap of 47pF. The reissues tend to be a bit more brittle sounding than the vintage DRs, or the re-builds -- such as what Ben Fargen did for me. I can get a great tone for both standard guitar and steel, even with the 47pF bright cap intact and using either a Reverend All-Tone 1250 (50W) or Weber 12F150 (also 50W) -- one in combo, other in extension cab, and with Weber Z-Matcher. But even a stock DRRI -- with stock PCB-construction -- can be good with steel if you tweak 'em right, IMHO.

Just as an aside, a stock DRRI used for steel could well be optimized by installing JJ 6V6 power tubes, biased to approx. 55% of max plate dissipation (not as hot as some lead guitarists might prefer) and with something like a Jensen Neo 12-100 speaker because it's not as dark as some choices but has a very smooth top-end ... and has (obviously) less speaker break-up compared to lower wattage speakers. YMMV.

Edit -- I thought of something to add: trying different makes of both preamp tubes and power tubes can do a lot to make tonal adjustments that don't involve removing your amp chassis and messing about in there. They are getting a bit more expensive, but there are so many excellent NOS preamp tubes can brighten or soften high-end response for use with different electric instruments. I was reluctant to discover this -- mostly because of cost -- but the really good NOS stuff does sound superior to my ears (*sigh* -- the $$).

The early to mid 60's shortplate Mullard 12AX7/ECC83 preamp tube has a bigger midrange and warmer tone compared to some common stock tubes. RCA grey shortplate 12AX7 preamp tubes (same era) may also be a good choice (the RCA 7025 tubes will be a bit brighter). Hungarian Tungsram preamp tubes are also good, but are getting pretty rare. Tubes such as Amperex Bugle Boys (Holland) and others with plenty of high-end extension would not be the best choice, especially if you use a brighter-sounding NOS power tube such as the still-common Philips 6V6.

The RCA blackplate (earlier) or 60's greyplate 6V6 is nicely warm but breaks up earlier ... I play at mostly living room volume levels, so that's not an issue. Playing out, I would put in a fairly hard set of JJ 6V6 power tubes. You can play the tone-balance game by putting somewhat brighter-toned preamp tubes with warmer-sounding power tubes, or vice versa. For max warmth, use a fatter, less bright NOS power tube with warm-sounding preamp tubes. And for reverb and phase inverter slot choices, I really like the Mullard 12AT7 tubes which are still really, really reasonable in cost!

You can get a bit more tightness and perhaps a tad more headroom (a harder set of JJ 6V6 tubes will still do more for headroom) by replacing the rectifier tube with a solid state plug-in but watch your plate voltage if you use another power tube besides the JJ. Raising your B+ would obviously increase your headroom but you'd probably be better off by having no more voltage drop than what the stock rectifier provides ... so you'd want to use a solid-state rectifier plug-in that maintains the 17V drop that a standard 5AR4/GZ34 rectifier tube will provide -- basically, reducing sag (if you like that tighter response) without raising B+ ... and Weber has a nice Copper Cap solid-state rectifier plug-in (the WZ34) which, in addition to using the JJ power tubes and warmer-toned preamp tubes, might be a good way to go. I can almost hear some say: "Just buy a Twin!" (or a Peavey steel amp) ... but I would try tweaking your Deluxe. I've learned that with tube amps, there are many things that can be done to make fairly surprising (and beneficial) tonal tweaks.

Isn't the far left tube the rectifier?

Bill A. Moore wrote:Isn't the far left tube the rectifier?

Correct -- looking at the rear of your map, it's the one farthest to the left.

As an FYI, if this tube fails by shorting out, it can take out the power transformer with it -- if there are no diodes in-line with this rectifier tube. The tube will simply not pass current if it fails open: you'll have no sound coming out of your amp -- "Hey, what's up?! I see lit up tubes back there, but no sound!" -- put in a new rectifier tube and all is fine.

Stout rectifiers are a good thing. Some Chinese 5AR4 tubes -- not too long ago -- routinely died after little use, but I think things have gotten better. The JJ rectifier is more stout, although I think the best tube rectifier is the Mullard (getting very expensive). The JJ is probably the best value when on a budget. It is interesting how there can be slight variations of sag between different makes and eras of rectifiers. If you really want to drive yourself crazy with tube-rolling, you can add rectifiers to the mix ... not just preamp and power tubes.

I choose not to do this -- I just installed a Mullard in my DR and forgot about it. I had a JJ in there before that.

The left-most tube, looking from the back, of a Deluxe Reverb is indeed the rectifier. If you had a rectifier tube fail, get a NOS rectifier tube. Modern tubes are not comparable. In 40 years, I have had exactly one NOS rectifier tube fail while I was playing it, in countless tube amps. I wish I could say the same for modern issue tubes. I gave up.

As far as rectifier tubes go, without a doubt a nice NOS Mullard GZ-34 (equivalent to a 5AR4) doesn't drop as much voltage as the other appropriate tube for a DR - 5U4 - which means, other things being equal, it delivers a higher voltage to your power tube plates. Agreed that this is nice for pedal steel, but not so much agreed that this is necessarily good for your Deluxe Reverb, especially if it's running new import tubes. The potential problem, IMO, is that Deluxe Reverbs (even the reissues, I think) tend to push 6V6 power tubes well past their plate voltage design limits even with the lower-duty 5U4. This wasn't so much a big deal with good NOS tubes since these old golden-era American-made tubes were heavily over-designed anyway. Deluxe Reverbs did push even them pretty hard, but they are very tough on these newer tubes. Putting a real efficient GZ-34 or a solid-state rectifier in a DR tends to really sock it to 'em.

So I would use a good NOS 5U4 rectifier in any Deluxe Reverb unless I was very sure about the hardiness of the power tubes. RCA, Sylvania, Phillips, pretty much anything that is from the 'good' years - 50s-80s - and has been tested at high voltages. BTW, a new Mullard is nothing like a NOS Mullard, IMHO.

A Deluxe Reverb is my favorite guitar amp, bar none. It's great for clean pedal steel in relatively low-volume situations if you do a few things:

1. Have a good high-headroom speaker.
2. Have really good output tubes - to me, this means NOS 6V6. I tend to use Phillips-Sylvania 6V6GT from the 70s-80s because they are readily available and don't cost an arm and a leg. My favorites are the 70s-80s GE tubes, but they're getting hard to find.
3. Deal with the hot signal from most pedal steel guitar pickups. I typically put a 5751 in the first Vibrato channel position (2nd tube from the right, looking from the back, this is assuming you use the Vibrato channel, and not the Normal channel). This lowers the gain a bit and tends not to distort as much. You can also lower the gain by using Input 2, you can do both if it still distorts.

A DR is great for practicing and relatively low volume rehearsals or gigs, providing you don't have a loud stage volume. Or if you like a distorted sound, well, that's not hard with a Deluxe. But I had to give up using my DR for 'normal' PSG gigs a long time ago - IMO, they just don't cut it in a 'normal' (i.e., LOUD) band mix without getting pretty ratty.

Strictly my opinions, based on my experience. You may be looking for something different than me, so YMMV.

Like i said, Im no expert,
but theres a few here...see what I mean

:!:Expert:
Someone whos not afraid to touch a hunk of electrified metal that just may kill you, because they know what theyre doing (Ken Fox for example).
if you DONT REALLY KNOW WHAT YOURE DOING, please dont try it at home,
Billy dont be a hero
be safe

If you like tube amps, a good tech is a good friend!
Clete

Yeah, Clete is right - unless you know what you're doing, don't go poking around inside a tube amp. If you're going to do anything more than replacing the rectifier tube or try some different preamp tubes, you probably need to get someone to look at it.

If you replace power tubes, the bias may or may not be correct. At the very least, you need to know what to look for if the bias is set very wrong, which means you turn the amp off and have someone competent set the bias. Ideally, every time the power tubes are replaced, the idling plate current should be measured and adjusted to taste, or at least a reasonable 'safe' operating point. Again, not something you can do yourself unless you know what you're doing inside a tube amp.

Whatever you do, don't ever replace the fuse with a higher rated fuse. When testing amps, I've even used a bit smaller value when I thought it had problems - better to blow too quickly than too late. Replacing with a higher-rated fuse or a fuse that blows more slowly than spec can lead to serious damage to an amp.

Gee Dave! You mean I shouldn't be using a .22 Long Rifle rimfire cartridge for a fuse?

Um, yes.

You'd be amazed how many people take an old fuse and wrap it with metal foil, or use a 15-20 amp fuse to rid themselves of that pesky "blown fuse syndrome". Frequently seen with blown transformers.

Dave, when I got my '56 Pro Amp, the blown fuse was covered with foil!. And I actually did read somewhere of someone using a cartridge as a fuse. I think it was in a car's fuseblock.

Dave Mudgett wrote:Yeah, Clete is right - unless you know what you're doing, don't go poking around inside a tube amp. If you're going to do anything more than replacing the rectifier tube or try some different preamp tubes, you probably need to get someone to look at it.

This is good advice. While it is true that some amplifiers have bleeding resistors to drain the high-voltage filter caps when the amp is off (and some folks strum a few chords as they turn the power off, with standby switch also off), those filter caps have enough high-voltage in them to kill you ... at the very least, give you a rather nasty shock. I once watched a friend open his amp and mess about in there -- I asked: "Have you drained the caps?" ... I have a special wiring set-up for this, with the proper resistors, and I've even done this wearing rubber gloves since I've been (mildly) shocked in the past (non-musical / household electrical, long ago).

Anyway, he replied: "Nah ... I think it's OK ... it's been off for awhile." Then a bit later, he starts re-tensioning pins with a stout bamboo dental pick sort of thingie -- yeah, OK, it's wood rather than metal, but even sweat (water+salt=conductive!) could possibly furnish a path for zappage and who wants to take a chance? Especially when one is not really sure of the drained condition (or not) of those filter caps. Also, at various times he had both hands on the chassis which, in case of zappage, would provide an electrical path right across his heart ... which is bad.

So, yeah ... it's good to be familiar with common ailments and repair strategies but if you are the least bit unfamiliar with the usual safe practices of opening an amp and servicing it, definitely take it to a tech! And you definitely don't want to grab stuff willy-nilly like this guy (who was lucky):
http://www.youtube.com/watch?v=oJblXWup ... re=related

Dave,
I used to work for a company that made Disco equipment. Neon dance floors, spots, and STROBES. We used the landing light strobe bulbs made for 747s. I was making a run of ten, under pressure to fill an order. Each had two big oil-filled 660 volt can caps. When I finished wiring one, I grabbed the chassis by the caps to put in on another bench. They were handy handles. I had forgotten to put in the bleeder wire! Every muscle in my body straightened out instantly! I flew backwards from the bench, and threw the chassis so hard into the wall, that I bent the heck out of it. I had one of those caps in each hand. I think I'm lucky to still be here! I've double/triple checked everything since then.

Yeah, I've had my share of shocks doing electro-physics and electrical engineering experiments over the years back when doing that kind of stuff. One 500 VDC electro-deposition experiment, I made the mistake of grabbing the wrong plate while unknowingly having my other hand on a ground. That was a high-capacity supply - if I hadn't set up a limiter on the circuit, I might not have gotten up.

I actually don't know too many EEs or electronics techs who haven't gotten blasted occasionally. But you do learn to be careful and to keep one hand in the pocket, as they say.

Got my first good shock when I was around 2/2 1/2 years old. Remember it very clearly! I somehow got my fingers into the outlet in my parent's bedroom. I saw the blue light!