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Thread: Tube rectifiers VS solid state, ???

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    Tube rectifiers VS solid state, ???

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    In all tube amplifiers, no matter the age, or maker, the tubes run on DC current.
    A rectifier changes the AC, (* normal house current 110-120 v) to DC current.
    In tube rectifiers, when power is applied, switched on, if there is no 'standby' switch, it warms up slowly and feeds the converted power to the rest of the tubes slowly as it warms up.
    With solid state rectifiers, they are 'instant on' type devices that send power instantly to the pre-amp and power tubes. In amps that have no standby switch, this can be very hard on the tubes, and lead to tube failure, or noisy tubes, micro phonics etc VERY quickly, cutting the life and useful sound by half or more...
    Especially with crappy tubes from China and Russia and any other cheaply manufactured
    factories...
    That is where a stand-by switch is helpful it allows the tubes to warm up before full power is applied to the plates.
    For all those using solid state amps,.... not a problem, no tubes crappy tone right out of the box.....
    For tube amps a VERY important bit of info....
    Not very much current production tubes are ANYTHING like the old stuff,... sketchy quality control, crappy materials, cheap production and not too much in the way of customer service.
    Not all are like that, but 75-85% are....
    Black Plate tubes are not made any more, as much as the tube makers say they are,.....
    They aren't.... that tech died with the engineers that came up with it. Mostly at RCA,GE, and Sylvania... What is touted as 'BLACK PLATE TUBES' now are just plate material painted black.....not really a coating of other materials , just high temp paint....
    Kinda like what a wood stove is painted with....
    Not at all sonicly equal to the REAL thing.
    All the differences are kind of gone when three or four pedals are put in front of the signal before it hits the amp.. the piercing harshness of thin plates, and crappy production is hidden by effects...and anyone who has never experienced the difference for themselves as well as those out in the audience are relly not getting any of that either....

    If anyone has questions please ask, I have a great many manuals and tech books concerning this, so iI I don't know right off, I can look it up...
    S
    Last edited by weakenduser; 01-13-2019 at 10:06. Reason: adding a bit

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    Just another added note, the statement above applies to ALL tube gear, whether Pre-amp,tuner,headphone amp, radio, HAM gear,PAs, and ALL other tubes.... they ALL run on DC current.
    S

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    OK...that info is nice to have for many folks who don't know much about tubes...but you kinda end on a negative note...as though tube with current production tubes is basically going to suck.

    I've got probably 3 or more cases of NOS & vintage used tube. Pretty much any kind of preamp or power amp tube you would find in guitar amps, plus some that are more specific to mics and mic preamps and other types of rack gear that uses more unusual tubes than your typical guitar amp.
    I also have quite a bit of current production tubes, and while I will roll tubes from time to time and try out the vintage stuff, I also use the current production tubes.
    I don't deny that some current production QC is sketchy, but there were plenty of crappy made tubes back in the day too...the big difference, back then there were millions of tubes being made, for everything...these days, the production is more limited. Point being, there was much less focus on "black plates" and this brand vs. that brand back in the day....they were just "tubes".

    This modern day obsession with analyzing vintage tubes down to the color of the ink used to mark them was not prevalent back when tubes were everywhere.
    So I think with a bit of tube rolling, you can find equally good modern day tubes as you can vintage ones, which are getting scarce, and much of what is being sold now are probably used vintage tubes, with very little being NOS, unused tubes....but it became a big business over the last 15 years, so both sellers and buyers started buying myth and legend and looking at all kinds of silly, minor details that could set one tube apart from another.

    I was lucky to buy most of my NOS and used vintage tubes 10-15 years ago before the madness kicked in full-tilt, and mostly I was buying them because there was less modern day production going on, but since then, modern tube production has stepped up and so has the QC.
    Three of my top-shelf, favorite guitar amps are using all modern day tubes...even though I have plenty of the vintage ones on hand, but I see no reason to re-tube them. They sound great as-is...and believe me, I've spent hours and days in the past rolling tubes and trying out stuff, and most times, it was the vintage tubes that didn't measure up, not the current production ones.
    There are a good number of resellers of both vintage and current production tubes that also do their own QC, so you get good tubes no matter which you choose...but these days the crazy mark-up on many vintage tubes is just....crazy! I guess some people just want to pay a lot extra for the myth and legend.

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    If your guitar amplifier has a standby switch the best thing to do with it is leave it ON and turn the amp on and off with the main power switch.

    This is especially the case if your amp HAS a thermionic, i.e. valve rectifier as it is these that are most likely to suffer damage from the standby switch.

    No other piece of valved electronic gear was fitted with a sb switch. Millions of radio sets and TVs were made and never a one had the useless devices. High fidelity amplfifiers never did. One tiny exception, some Public Address amplifiers. This was simple because these were often run from lorry supplies and the HT was turned off to save battery drain but keeping a fast start.

    I will agree that there is much dross out there regarding valves. Definitely caveat bloody emptor!

    Dave.

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    Quote Originally Posted by ecc83 View Post
    If your guitar amplifier has a standby switch the best thing to do with it is leave it ON and turn the amp on and off with the main power switch.

    This is especially the case if your amp HAS a thermionic, i.e. valve rectifier as it is these that are most likely to suffer damage from the standby switch.
    I think you're overstating something that is really not true.
    I've used amps with standby switches for years, and have never suffered any "damage".
    The only potential damage could occur when people flip the standby switch off/on/off in too rapid succession...but a properly designed/fused amp will be able to handle that, and you might just blow the fuse. So just avoid the rapid standby off/on/off...and you will never suffer any damage from it.

    The real benefit of the standby IMO is for live performance use and/or in the studio when you need to change guitars or try out a variety of pedals, etc...and then you can just flip the amp on standby and go about your business. Without it...what are you going to do, keep powering your amp down?
    That's going to create potentially more issues...and you also don't want to turn off the amp's volume every time if you have the amp dialed in just where you want it. So the benefit of the standby (not even mentioned the warm-up/warm down) outweighs the rare occasion someone may improperly use it and maybe cause some kind of damage.

    Oh....AFA the actual title of this thread...
    Each type of rectifier has it's use in shaping the response of the amp when you play...so it's not just about which type is better for the power tubes.

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    Quote Originally Posted by miroslav View Post
    I think you're overstating something that is really not true.
    I've used amps with standby switches for years, and have never suffered any "damage".
    The only potential damage could occur when people flip the standby switch off/on/off in too rapid succession...but a properly designed/fused amp will be able to handle that, and you might just blow the fuse. So just avoid the rapid standby off/on/off...and you will never suffer any damage from it.

    The real benefit of the standby IMO is for live performance use and/or in the studio when you need to change guitars or try out a variety of pedals, etc...and then you can just flip the amp on standby and go about your business. Without it...what are you going to do, keep powering your amp down?
    That's going to create potentially more issues...and you also don't want to turn off the amp's volume every time if you have the amp dialed in just where you want it. So the benefit of the standby (not even mentioned the warm-up/warm down) outweighs the rare occasion someone may improperly use it and maybe cause some kind of damage.

    Oh....AFA the actual title of this thread...
    Each type of rectifier has it's use in shaping the response of the amp when you play...so it's not just about which type is better for the power tubes.
    I agree that there are good and bad implementations of SB switches. There are also design/legal/marketing problems. Putting the switch in the AC side of a full wave circuit is the worst news for the valve rectifier. The solution is to have it post the first smoothing capacitor so that the rect valve does not have to cope with the peak current demand of the caps and the hot power valves. The problem here is that switches rated at 300V DC and above are not common nor cheap. Most often manfctrs use a 250V component and take the chance. I have never read of a problem with a 250V rated switch having 450V+ on it but it IS uncomfortable to use a component out of its ratings. There is also the issue of a capacitor left charged to peak AC for the unwary service tech!

    The "muting" point is well made but there are at least two other ways to do that. One very easy one for a valve amp is short the speaker jack.

    The guitar amp public love their stand by switches! I know this because the company I worked for produced a 20W EL34 amp without one and the moaning was palpable! In practice all the player needed to do was pull the input jack. That put -100V or so on the 34's grids and shut them up.

    I understand the company has not since omitted the SB switch on any subsequent valve designs even though the chief designer hates the bloody things!

    "Sag" can be done by the grossy inefficient practice of inserting resistance in the HT rail of a solid state rectifier. Much more can be read about this in the books by Merlin Blencowe.

    I know I am on a hiding to nothing here but the fact remains that valve guitar amps are and were just about the only common piece of valve technology that had such switches and the reasons are lost in the mists. There are several theories, muting being one but nothing definitive.

    Dave.

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    Like I said...when it's well designed in the circuit, with the right quality/spec components, it works fine...and while I do get some of the "letting the tubes warm up" reasoning, for me, and probably most players is the muting that makes it a very useful feature...and there's no mists surrounding that perspective.

    I have a Savage Mach12X (super amp) that originally came without one...and it was always a PITA in the studio, because often I will try out 4-5 guitars when doing a couple of tracks...and I don't want to touch the volume knob on the amp.
    So, I kept looking at it...it's a combo with a top faceplate, like a typical Fender Deluxe amp...and I could visualize a spot next to the power switch where a standby could be added, but I didn't want to start drilling holes and maybe mucking it up.

    Anyway, I was talking to Savage Amps about it, and there was some other thing (don't recall what)...so they told me to send the chassis to them, and they would check it out...and they suggested that rather than drilling another hole for a standby switch, they could swap out the power switch and make it a dual operation Off-Standby-On switch, using the same existing hole...which I was very happy about. I had also explained to them what the PITA was with not being able to mute the amp during guitar swaps, etc...and wouldn't you know it, once they saw the opportunity to easily add the standby without having to retool the faceplate and chassis, they said they loved the idea, and were going to include it on all their subsequent amps.

    Long story-short...it works great, and yeah, it's a very high voltage switch. Sure, they cost a few bucks more, but when you have a top-shelf amp...it's not a big deal. When you're trying to design inexpensive tube amps...then you have to cut corners to add in features, and also use cheaper components.
    I've got several other high-ends amps with standby switches, and the switches and everything else in them is top quality...so not much worry about anything being damaged or falling apart on me.

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    I hate recto tubes. Silicon is my jam.

    Although I fully admit I prefer germanium when it comes to transistors for fuzz circuits.
    My home studio ---> www.nerolstudio.com

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    I have to wonder Miroslav why that no doubt excellent but expensive amplifier was originally designed without an SB switch? Perhaps the designer was, like "our" bloke, technically averse to them?

    There is nothing "low quality" about the switches I spoke of, just that they are rated by the mnfctr at 250V, aspersions need not be cast. The guitar amplifier market is one of THE most competetive and not everyone can have "boutique" gear. Any silly bugger can build fabulous kit if you give them a blank cheque.

    The mute function is the only useful thing about SB switches and I have already shown two alternative ways to do that. Or, if swapping guitars is required, get a Neutrik Silent plug cable.

    But, I repeat, I know I am a lone voice here!

    Dave.

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    Quote Originally Posted by ecc83 View Post
    I have to wonder Miroslav why that no doubt excellent but expensive amplifier was originally designed without an SB switch? Perhaps the designer was, like "our" bloke, technically averse to them?
    I'm not sure what you're implying here?
    I can't speak for the amp designers...but when I consider that some high quality amps that get no grief from users about their design and component implementation, come WITH standby switches and not some other way to mute or to provide a stepped power up/down process...
    ...I'm pretty confident that the builders new what they were doing, and if there was any danger of some damage occurring with the use of the switch, it went into their though process.
    These are not assembly-line, mass produced amps...but ones that often cater to some very selective players, so the builders are not going to half-ass a design just to please some "misguided" need for a standby switch.

    There may be other options for muting...but the standby switch has been the go-to choice for like the last 60+ years of amp building...so I think its safety has been well vetted.
    The "silent cable" might work for some...but it's just a solution at the guitar end. If you have to swap out pedals, etc...you would need multiple silent cables and some fumbling around. A standby switch is just makes it all too easy...plus it lets you lower the power/heat consumption at the amp when you're taking a break, without having to shut off the amp...and most people feel it's kinder to the tubes.

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