Tube Rectifier and the Silicon Diodes. Not sure what it is.

[jackieTHEjokeman]

In the back of most of the Mesa's (Stiletto, Rect) You can switch from Tube or Diodes. Do silicon diodes mean that it turns it into a "solid state" amp and bypasses the tubes? Can some put these into laymens terms please. Thanks.

 

[Guitarzan]

Only solid state rectification. The purpose of the rectifier is to turn the AC from your wall to DC that is useable in the amps circuits.

 

[Silverwulf]

+1 to the above. In either mode, you'll still be using your preamp and power amp tubes. The only thing that switch will turn on and shut off is the rectifier tubes in the amp, which are the really big ones you see.

 

[jackieTHEjokeman]

So, the sound can be changed from just a different source of power?

 

[strumminsix]

So, the sound can be changed from just a different source of power?

Yes the sound can change but no the power source is still the same. Reread what Guitarzan wrote cuz he was right on the money. I'll explain it further...

AC = Alternating current
DC = Direct current

Most every electronic items work off of DC since that's the way it works. DC in it's simplest analogy is like a stream of power. A stream goes one direction so the current (see the water analogy continue) is called direct.

When electricity was put into homes it was originally DC. But they soon faced the problem that DC cannot be pushed in great distances. To overcome this, Tesla (scientist not hair-band) came up with AC which can be thought of as a push-pull sort of current.

Think of cutting down a large tree using a handsaw do your run the blade one way then pull it out of the wood and run it back? Nope, you go back and forth. Very similar concept.

AC is able to travel HUGE distances based on design so it became the standard.

Now, amps run on DC (like most everything) so you need to convert AC to DC and that is rectification. This can be done using tubes or diodes.

Hope this helps or is at least informative.

 

[jackieTHEjokeman]

Yeah definently. Thanks.

 

[tele_jas]

When switching to the different rectifier, you may notice a more or less spongy attack when playing. Some prefer the solid state rectifier for harder tones and the classic rock guys and country guys seem to perfer the tube rectifier, but thats not always the case and many also like it the opposite way. To each his own :wink: , I personally like the tube for both.

 

[RR]

Besides the above, here some additional info ... for what its worth.


Using tube rectifier is ancient technology that was pretty much replace with the more efficient, lesser expensive and more reliable solid state in the mid 60's.

Tube rectifier was reborn in the era of all these boutique guitar amp manufactures were popping up all over the place building or replicating "vintage sounding" amps, using recitifier tube(s) to get a "vintage tone".

[my opinion] Randall Smith decide to incoporated this old technology and with the option selecting either tube or solid state rectifier in his amplifiers. If I'm not mistaken, I think actually Randall Smith had a patent on switchable rectifier (solid state or tube). But the patent ran out.

Rectifier tube(s) softens the attack of your playing style. Some call it "sag" which actually is the voltage term. When you play with medium distortion, you "might" be able to "hear" the difference between a tube rectifier and a solid state rectifier.

I think the majority of the guitarists prefer diode mode since it very aggressive. Gives you more edge. It's louder.

Its a matter what you prefer.



I don't want to bring up dead threads but personally I got the impression (my nomenclature) when MESA Engineering had the "Dual Rectifiers" written on the chassis of amplifiers it meant "switchable" rectifiers (solid state or tube(s)). Look at the front panel of Mavereick, Trem-o-Verb, Road King I, II, Blue Angel of course Dual Rectifier. It says "Dual Rectifiers" on the front chassis.

BUT Other MESA Boogies amps with switchable rectifiers (tube(s) / diode) without "Dual Rectifiers" written on the front panels include Stilletos, the two LoneStar models and HeartBreaker.

Then the Triple Rectifiers has "Triple Rectifiers" on the front panel which throw "my nomenclature" out the window. :?

 

[strumminsix]

Then the Triple Rectifiers has "Triple Rectifiers" on the front panel which throw "my nomenclature" out the window. :?

reminds me of spinal tap:
Nigel Tufnel: The numbers all go to eleven. Look, right across the board, eleven, eleven, eleven and...
Marty DiBergi: Oh, I see. And most amps go up to ten?
Nigel Tufnel: Exactly.
Marty DiBergi: Does that mean it's louder? Is it any louder?
Nigel Tufnel: Well, it's one louder, isn't it? It's not ten. You see, most blokes, you know, will be playing at ten. You're on ten here, all the way up, all the way up, all the way up, you're on ten on your guitar. Where can you go from there? Where?
Marty DiBergi: I don't know.
Nigel Tufnel: Nowhere. Exactly. What we do is, if we need that extra push over the cliff, you know what we do?
Marty DiBergi: Put it up to eleven.
Nigel Tufnel: Eleven. Exactly. One louder.
Marty DiBergi: Why don't you just make ten louder and make ten be the top number and make that a little louder?
Nigel Tufnel: [pause] These go to eleven.

 

[tele_jas]

Novice question here.. is that same as the Pentode/ Triode? it says normal for tube and hi-power for diode. is that same as ahalf power switch? and what does the spongy and bold switch on the back of rectifiers do?

Thats the same thing as Pentode/Triode :wink: And the bold/spongy switch is the "half power" switch or variac you are talking about. Like I said, the pentode/triode thing is more of a feel thing, but there is an audialbe difference when doing an A/B comparison but I bet most people couldn't tell what setting one is on just by hearing one.....It is more of a feel thing.

 

[mloiaco]

The terms Diode, Triode, Pentode, etc. refer to the number of elements inside of a vacuum tube.

In terms of the Stiletto or the Road King, Pentode/Triode refers to the number of active elements in the EL34 power tubes.

I won't bore anyone here with the details of tube operation, but I will try to explain the difference between triode and pentode in idealized scenarios, and in layman's terms.

---------------------------------
Diode (TWO ELEMENTS:
The path of the electrons inside the tube is:
cathode (-), plate (+)

Your rectifier tubes are diodes. They rectify (convert AC into DC) because the plate can only attract electrons from the cathode when it is (+) charged. Since the plate is driven by AC (periodic (+)/(-)), it only attracts electrons during the (+) periods. Therefore, although the (-) periods will cause the output to be 0, it certainly eliminates the (-) part of the AC. Thus we have DC (although it is inefficient DC since we have these idle periods).
-------------------------------------
Triode (THREE ELEMENTS):
The path of the electrons inside the tube is:
cathode (-), control grid (-), plate (+)

Comment: By introducing a (-) control grid, we make it more difficult for the electrons to reach the plate. You can think of this as one way of controlling the volume of your amp as follows: When you turn the volume knob up, you reduce the (-) charge on the control grid, thus making it easier for the electrons to reach the plate. Note that even a small change in the grid voltage has an enormous effect on the number of electrons that reach the plate.
---------------------------------------------
Pentode (FIVE ELEMENTS):
The path of the electrons inside the tube is:
cathode (-), control grid (-), screen grid (+), plate (+)

The fifth element is a *pair* of (-) charged "beam confining" shields which help to "shape" the ribbon of electrions and keep them focused on the path between the cathode and the plate (otherwise, some electrons would fly off to the sides of the tube, away from the plate).

To summarize:
1. Your rectifier tubes are diodes.
2. EL34's are pentodes, but your Stiletto or Road King can operate them in triode or pentode mode. In triode, there is only a control grid between the cathode and the plate. In pentode, there is an additional screen grid and a beam confining shield.
3. The result is that triode mode is looser, scoopier, creamier, more forgiving, and sounds more "airy." While pentode mode sounds more pointed, tight, and clips much higher than triode.

Personally, on my Road King, if I'm using EL34s for a clean or vintage-near-clean sound, then I use triode. Otherwise, I use pentode.

If you want to learn more about tubes, I recommend:
1. http://www.vacuumtubes.net/How_Vacuum_Tubes_Work.htm
2. At the end of the Road King owner's manual (which is available on Mesa's website), there is a great article by Randal Smith called, "On Triodes, Pentodes & Irishmen"
3. Randall Smith's article "Class A Explained."

 

[Bren10]

First off... to RR:
I don't really understand what you're talking about in terms of nomenclature. But, there's something that you failed to mention and therefore might not fully understand. So, if I tell you, maybe it will help... or... maybe not.
The Lone Star models (and others you mentioned) have switchable rectifiers but only one of each. The Dual and Triple Recs have a seperate rec tube for each output tube pair. The Road King is this way too, I guess. So, The Single Rec and RectoVerb have 1 rec tube, the Dual Rec has 2 as does the Roadster, and the Triple Rec has 3. Maybe this helps?

And now to Anomaly:
The rectifier switch is deffinitely NOT the same as "Petode/Triode" and also NOT the same thing as "Half Power".

Here are some general guide lines:
1)"Half Power" is achieved by using less output tubes. So, If you have a 100 watt amp that uses 4 output tubes, "Half Power" will use 2. You may have a switch or you may just have to take two of the tubes out (Don't do that unless you know what you're doing).
2)"Pentode/Triode" is a way to change the character of your output tubes. Switching to "Triode Mode" does indeed lower the output but that's not the goal. The goal is to induce a faster onset of output tube distortion. FYI: any loud amp wiull still be really load in either mode.
3)Tube rectifiers can't produce the same amount of juice that Solid State ones can. That would explain the "Normal" and "High-Power" designations. The Solid State or "Silicon Diode" rec is gonna' give you more Boom Boom just because it can get more juice to the tubes. Although, I agree with tele_jas. This will be more of a feel issue than a volume one. By the way, to re-iterate what mloiaco said, the tube rec is still a "Diode"... just not a silicon one.

 

[cnumb44]

Let me see if I can muddy it up even further. I see it as 3 types of power altering techniques for tube amps.

Type one - changing the number of power tubes that are being used. When you go from full to half power (100W to 50W) you use fewer power tubes (4 versus 2).

Type two - changing the active elements within a power tube. Moving from pentode to triod also reduces the power output of the tube, but it really changes the sonic characteristics. On the old fenders you could go from pentode to triod and it changed your output power significantly (60W to 25W I think).

Type three - changing the line voltage at the input transformer. On the LSC there is an option for full or tweed power, and that is essentially a variac that lowers the actual input transformer voltage.

So if you are in 50W mode and using tweed, you are really getting about 33W of power out of the 2 tubes you are using.

I hope that makes sense and that I haven't messed up anyone's mind. The terminology gets confusing and this is just how I think about it.

 

[Bren10]

Jerry, I totally agree with everything you're saying. Let me just say one more thing to clarify what I was saying about the "Pentode/Triode" subject.

It is true that in "Triode" mode, you will have less output and volume. Also, (This is the part that I think is Important to understand) your output tubes will break up a lot sooner. So, if "Poorly Maintained Plexi" tone is what you want, have at it. I personally love that sound.

Anyway, cheers to all

 

[RR]

First off... to RR:
I don't really understand what you're talking about in terms of nomenclature. But, there's something that you failed to mention and therefore might not fully understand. So, if I tell you, maybe it will help... or... maybe not.
The Lone Star models (and others you mentioned) have switchable rectifiers but only one of each. The Dual and Triple Recs have a seperate rec tube for each output tube pair. The Road King is this way too, I guess. So, The Single Rec and RectoVerb have 1 rec tube, the Dual Rec has 2 as does the Roadster, and the Triple Rec has 3. Maybe this helps?

Yes Bren10 I'm aware of of the LoneStar models and Road Kings switchable rectifiers and I'm aware for each rectifier tube is to power a pair of power stage tubes. Yes I did fail to mentioned each tube to power a pair of power stage tubes.

If you read carefully I mentioned that the LoneStars Models has rectifier tube(s) .

BUT Other MESA Boogies amps with switchable rectifiers (tube(s) / diode) without "Dual Rectifiers" written on the front panels include Stilletos, the two LoneStar models and HeartBreaker.

Is this where I mislead you?

My point is that look at the chassis of Maverick, Trem-o-Verb, Road King I, II, Blue Angel ...

Now what does it say on the front panel of these amps? => "Dual Rectifiers" written on the chassis of ALL these amps. Look for yourself. Look at E-Bay, MESA Boogie site of discountinue amps...

Now what does that means? Does it mean it has two tube rectifiers? Nope, not necessarily. Could it mean its switchable rectifier either tube or solid state (diode). That's a good possiblity. And this is what I mean about my nomenclature. These amps mentioned has both rectifiers solid state or tube.

Did I say if a MESA/Boogie amp doesn't have "Dual Rectifier" it does not have switchable rectifiers between tube(s) or solid state? I did not say that! Maybe you got mislead I said that. Re-read my post.

I say my nomenclature fails because "Tri-Rectifier", what does that mean? Three rectifier tubes? Yes that's possibility. Could it mean switchable for diode/ tubes(?)/ or what else? Nope.

So, The Single Rec and RectoVerb have 1 rec tube, ...

I never knew Single Rectifier and RectoVerb has a rectifier tube? Is this true? But I'm not familiar with these two amps.