Tube rectifiers VS solid state, ???

[weakenduser]

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

 

[weakenduser]

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

 

[miroslav]

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.

 

[ecc83]

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.

 

[miroslav]

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.

 

[ecc83]

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.

 

[miroslav]

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.

 

[Guitargodgt]

I hate recto tubes. Silicon is my jam.

Although I fully admit I prefer germanium when it comes to transistors for fuzz circuits.

 

[ecc83]

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.

 

[miroslav]

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.

 

[ecc83]

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.

I "imply" nothing. I am sure, as you say the designers are top blokes. I have said several times that my views on the switches are not shared by many but they are supported by some in the industry.

There is no evidence that the SBS prolongs valve life. In radios and PA amps power valves lasted a decade, often two or more (you could NOT kill a 6V6!) but in a guitar amp in constant, hard use a year is good going sometimes. Why? Because the valves fail catastrophically due to being overdriven. That last is not a "bad" thing, it is what players DO to amps and the fact must be taken into account by the makers(I spent a good deal of my time trying to bugger amps!)

Many valve amp circuits are simply clones of older designs complete with mistakes. The uneven PI anode loads is one example. Often power valves are given G2 resistors too low in value and G2 failure (under clipping) is the #1 failure mode. Some circuits have no G2 Rs at all!

But let us leave this in peace? We shall not agree and you like the SBS convenience.

Dave.

 

[weakenduser]

having close to 35 years of tube knowledge, and close to that in amp building and with both in mind, I half agree with both of you guys,.... a standby switch in a modern guitar amp is a big benefit to those who want to take a break for 15-30 minutes for lunch, or other things, but is not an essential component for amp operation. However, the subject of this thread is to discuss the benefits and pitfalls of the rectifier in any amp, or actually any tube gear.
The original designers of tube gear, the engineers at Western Electric in the late 20s and early 30s, at least here in the US, used the only thing that was available then, a tube rectifier. Solid state and whatever that brings was not around till the late 40s early 50s,...
Leo Fender used some of the original WE info to begin building his Guitar amps.... and still no solid state existed... The sbs was not introduced till mid to late 50s...
And an added note, sorry about my rant on NEW production tubes, I was mainly referring to the Pre-amps and it does relate to how shitty most of the cheap Chinese and Russian brands are.
S

 

[miroslav]

However, the subject of this thread is to discuss the benefits and pitfalls of the rectifier in any amp, or actually any tube gear.

Yeah...no problem. You kinda brought up the standby switch in your first post...and ecc83 picked up on it, and I also responded.

Anyway, I'm not really sure what discussion you're looking to have regarding tube vs. ss rectifiers....?
You seemed to suggest in your fist post that tube were better than ss...but that modern tubes suck...so...what is it that you want to discuss exactly?
I thought you were just providing some background info on rectifiers and NOS vs. current production of tubes.

 

[weakenduser]

Sorry for the miss direction.....
I do think overall a tube rectifier is much better for the life of any tube operated gear. Speaking from experience, I have seen a lot of amps with solid state rectifiers that when new power tubes were installed, had 20-30% less usable life than an amp with a tube rectifier that had power tubes installed during the same week. overall the tubes seemed to just sound better as well.... and
as a whole new production Power tubes are generally OK, as really they do not provide tone, only pushing out the signal to the output section.
It is the Pre-amp tubes that are the most important to the tone and feel of any amp anyway.
With the introduction of effects, even premium tubes of ANY kind are totally overshadowed by the change in the signal, and all the tonal differences are pretty much lost, except at lower wattages and volumes. this is especially true in a recording situation.
By the way, I joined this board in the early years, and after a computer crash, lost all the info needed to sign back in using my original handle of .'UpstateNY' I think it was in 2002 or 2003
S

 

[miroslav]

my original handle of .'UpstateNY' I think it was in 2002 or 2003

What part of upstate?
I'm in the Middletown/Orange County area...though I use to live up in Columbia County, just north of Red Hook/Rhinebeck.

 

[weakenduser]

6 miles south of Lake George.... about a mile from exit 19 off the northway....
Lived in Kingston for a couple of years before moving up here.

 

[RFR]

Power tubes are generally OK, as really they do not provide tone, only pushing out the signal to the output section.
It is the Pre-amp tubes that are the most important to the tone and feel of any amp anyway.

As a player (not an amp tech) I partially disagree with this.
Power tubes are quite important to a good 'tube sound'
Relying on just preamp tubes for the saturatuon never sounds as good as when the power tubes are cooking.

In the 80s I spent a bit of time with Mike Soldano. After the popularity of his SLO head rose, people were requesting a rack mount preamp version.
Mike was reluctant to do this, saying it would never sound as good.
But public demand prevailed.
It was the exact same front end as on his amps, but didn't sound the same. Half of what made a Soldano a Soldano was missing.
Of course you can factor in all the rack gear that was in vogue at the time as contributing to it not sounding the same. But long story short, the rack 'SLO' never took off like the amp. It just didn't have that sound.

Anyway, I think power tubes are a big part of the sound. Much like an electric guitar doesn't sound good without an amp. Maybe not that extreme, but I think you get my point.

 

[cfg]

Guitar player with anecdote here. I've owned a decent number of amps over the years, some tube and some SS rectified, and I've played many others. My go to amp today is an SS rectified Blackstar HT40 with an EVM12L, and I recently bought a Peavey Delta Blues (loaded with an EVM15L) which is SS rectified, and no slouch either, although a different flavor than the HT40, preferring Strat's more than the Les Paul that the HT40 favors. Prior to buying the HT40 (initially because the price made it too good to pass up), I was solidly in the "must be tube rectified camp", not because I hadn't AB'd a large enough sample of both to form some kind of opinion, but because I bought the tube rectified is better argument without applying a sufficiently critical ear and/or overcoming my biases and prejudices that came from reading. I can't add anything more useful here than to say that my SS rectified HT40 - with one cord and no pedals - inspires me to play more often and better than any other amp I've owned or played, and that has to count for something. I'm open to the idea that there's a tube rectified amp out there that would have me retire the HT40, but I haven't heard it yet.

 

[ecc83]

Sorry for the miss direction.....
I do think overall a tube rectifier is much better for the life of any tube operated gear. Speaking from experience, I have seen a lot of amps with solid state rectifiers that when new power tubes were installed, had 20-30% less usable life than an amp with a tube rectifier that had power tubes installed during the same week. overall the tubes seemed to just sound better as well.... and
as a whole new production Power tubes are generally OK, as really they do not provide tone, only pushing out the signal to the output section.
It is the Pre-amp tubes that are the most important to the tone and feel of any amp anyway.
With the introduction of effects, even premium tubes of ANY kind are totally overshadowed by the change in the signal, and all the tonal differences are pretty much lost, except at lower wattages and volumes. this is especially true in a recording situation.
By the way, I joined this board in the early years, and after a computer crash, lost all the info needed to sign back in using my original handle of .'UpstateNY' I think it was in 2002 or 2003
S

I would like to see the methodology that finds that 20-30% reduction in valve life. The idea that a valve rect "brings HT up slowly" won't wash because Vrects heat up faster than power valves and by the time the latter are emitting HT is well established. Sound qualities are so subjective that no meaningful data can be obtained but note that in any given amp chassis a valve rect will give slighlty less HT voltage than a pai of diodes. Is a correction made for Va, bias and escpecially VG2? Of course not.

In the thousands of YT vids showing the "night and day" differences between valves never do they use a "flat" reference microphone. Never is there a before and after DC voltage conditions table. Never a gain difference check and NEVER an SPL meter so we know things are being compared at the same sound levels.

It would very interesting (to me at least!) for some undergrad to do a well controlled test of the common guitar amp Wive's Tales. Trouble is, no matter HOW impeccable their research, the vast majority in the business would still dismiss it! Such research would need a good wedge of funding and would hardly be in the interest of the major guitar amp mnfctrs and DEFINITELY bad for many "boutique" builders!

Dave.

 

[weakenduser]

For the most part I stand by my comments, and with the understanding that all of it sort of depends on the tastes of the player. Having said that there are exceptions to every rule.... some power tubes do make a difference as anyone who has an amp freshly re-tubed will tell you...
especially if it is a 6L6 amp and the old tubes had 150 hours on them, and were EI or Groove tubes, etc and the re-tube installed Vintage Black Plate RCA tubes. Yes, HUGE difference, but for the most part the power tubes only add punch and volume, and in some circuits can add a bit of extra feel to the amp,... but for the most part after 15-25 hours, not really any tone benefits to speak of..... This statement also depends on ....Guitar electronics, type and size of the speaker, volume and picking or strumming dynamics, IE hard or soft.....
Tubes can also be questionable right out of the box, and even a slew of testing on several machines, will not guarantee how they will perform in an amplifier.
One more critical fact,..... any amp, solid state, tube or combination will react poorly to any fluctuations in AC power,.... a drop of 3-4 volts can make a world of difference...or a spike of the same in higher voltage....
If any of you has ever played a club that has power fluctuations, you know exactly what I am talking about....Hey how come my amp sounds so shitty tonight ??? it was great at our rehearsal...????
Check the voltage you are plugging it in to.....
S