Dual and triple rectifiers- what's the effect?

kwk13

Gold Supporting Member
Messages
185
So, the terms Dual and triple rectifiers in the Mesa line don't necessarily have much to do with the type of tone the amp gets (aside from the solid state vs. tube rectification), the "Mesa sound" really has more to do with the preamp? I think that's what I understand so far from theoutput of the thread. The multiple rectifiers are more to give a choice between solid state vs. tube rectifier tone and the number of rectifiers needed to handle the power output?

Thanks for all the help on this stupid question!!
 

AL30

Member
Messages
3,002
Well that was ... entertaining.

Anyway - why the need for the Dual Rectification? I read the posts and your comment on supplying enough current. So, why isn't there enough current? Couldn't this be remedied? Is this a design flaw (I don't mean that to be degrading) or is it actually necessary?

AL
 

Jef Bardsley

Member
Messages
2,952
So, the terms Dual and triple rectifiers in the Mesa line don't necessarily have much to do with the type of tone the amp gets (aside from the solid state vs. tube rectification), the "Mesa sound" really has more to do with the preamp? I think that's what I understand so far from theoutput of the thread. The multiple rectifiers are more to give a choice between solid state vs. tube rectifier tone and the number of rectifiers needed to handle the power output?

Thanks for all the help on this stupid question!!
Right. The rectifier choice has more to do with the attack envelope than the tone, and you'll get the same difference on any amp.
 

scopeboy

Member
Messages
36
Yes kwk13, that is the way I always understood it, anyway.

As for why they use multiple tube rectifiers, I don't think it is easy to get a single rectifier tube that will handle enough current to drive a 100 watt or 150 watt amp. There are only a few types of rectifier tube still in production, and AFAIK the strongest one you can get is the 5AR4/GZ34, which still really is only enough for a 50 watt amp.

So if Mesa wanted a 150 watt amp with tube rectification, they had to use three rectifier tubes, like a previous poster said.
 

John Phillips

Member
Messages
13,040
Yes, exactly - it's because of the current rating of rectifier tubes. A 5U4 - the type Mesa use - is limited to 275mA. (GZ34s are 250mA, 5Y3s are only 125mA for example.)

A 50W amp draws approximately 250mA at full power (bearing in mind that a typical amp is no more than 50% efficient, so the power supply needs to provide 100W, and at a voltage of 400V that would require exactly 250mA - the real figures will vary slightly depending on the voltage and the exact efficiency), so a single 5U4 or GZ34 is only enough for a 50W amp. A 100W amp needs two, and a 150W amp needs three. It doesn't matter how many power tubes are used to produce the power - a 2x6550 amp can produce 100W too, and would still need two rectifier tubes. A 4xEL84 amp only needs one because it's limited to around 45W at most.
 

iggs

Member
Messages
2,619
What's ironic is that the trademark massive, resonant, scooped crunch that they do so well has become called a 'rectifier' (or even 'rectified') sound, when it has almost nothing to do with the rectifier and almost everything to do with the preamp... :)
Even more ironic is the fact that most DualRec guys don't even use the tube recto mode but opt for SS rectifier since it gives a tighter sound and works better for heavy music.

:crazy
 

JPW

Member
Messages
507
Yes, exactly - it's because of the current rating of rectifier tubes. A 5U4 - the type Mesa use - is limited to 275mA. (GZ34s are 250mA, 5Y3s are only 125mA for example.)

A 50W amp draws approximately 250mA at full power (bearing in mind that a typical amp is no more than 50% efficient, so the power supply needs to provide 100W, and at a voltage of 400V that would require exactly 250mA - the real figures will vary slightly depending on the voltage and the exact efficiency), so a single 5U4 or GZ34 is only enough for a 50W amp. A 100W amp needs two, and a 150W amp needs three. It doesn't matter how many power tubes are used to produce the power - a 2x6550 amp can produce 100W too, and would still need two rectifier tubes. A 4xEL84 amp only needs one because it's limited to around 45W at most.
Just curios, but could you use a 5y3 rectifier tube in a germino lead55 lovo running with 6v6's. I heard somebody talk about this before and they used it to make the amp break-up sooner I think? Just curios cause I don't know.
 

kwk13

Gold Supporting Member
Messages
185
I guess what's interesting to me (or should I say confusing then) is why they chose to call the amps "Rectifiers" when in effect (I'm assuming here) that any 100 watt, tube rectified amp would be a "dual rectifier" and any 150 watt, tube rectified amp would be a "triple rectifier". I guess the "dual" they were going for was the switching of solid state rectifier to tube- although that's lost on the "triple" becasue you are really only dual rectifying (tube or SS) three channels? I guess it's really all semantics.

Thanks for all the great info! I've just always been curious what the meaning was and I think I get it now.
 

sosomething

Member
Messages
2,682
I guess what's interesting to me (or should I say confusing then) is why they chose to call the amps "Rectifiers" when in effect (I'm assuming here) that any 100 watt, tube rectified amp would be a "dual rectifier" and any 150 watt, tube rectified amp would be a "triple rectifier". I guess the "dual" they were going for was the switching of solid state rectifier to tube- although that's lost on the "triple" becasue you are really only dual rectifying (tube or SS) three channels? I guess it's really all semantics.

Thanks for all the great info! I've just always been curious what the meaning was and I think I get it now.
Not quite, because as John stated a SS rectifier (the kind most amps use) is perfectly capable of handling 100 watts of power and more. Marshalls, for example, use SS rectifiers - thus making them (even the 200-watt Majors) single rectified designs by any definition.
 

scopeboy

Member
Messages
36
The name is just a marketing tag. If you expect it to mean something, that's like asking what kind of shells a Dodge Caliber fires. ;-)

They probably called the original Dual Rectifier by that name because, hey, it had two rectifier tubes and nobody had bothered doing that before: they just used solid-state rectifiers once they got beyond what a single 5U4 rectifier could handle. Once they had a dual rectifier, hey, why not go one better!

Designs from the "original" tube era hardly ever used multiple rectifiers to handle higher currents. Once you got above what a single 5U4 or whatever could take, it was time to go to mercury vapour rectifiers like the 866. Then silicon diodes came along and killed tube rectifiers.
 

John Phillips

Member
Messages
13,040
Marshalls, for example, use SS rectifiers - thus making them (even the 200-watt Majors) single rectified designs by any definition.
Actually the Major - certainly the very earliest ones, I think they may have changed later - does use dual solid-state bridge rectifiers in parallel, for the same reason... the diodes available back then couldn't handle enough current. If you look at the schematics, only one bridge is shown, but it's labeled 8xA10D10.

:)
 

sosomething

Member
Messages
2,682
Actually the Major - certainly the very earliest ones, I think they may have changed later - does use dual solid-state bridge rectifiers in parallel, for the same reason... the diodes available back then couldn't handle enough current. If you look at the schematics, only one bridge is shown, but it's labeled 8xA10D10.

:)
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Thanks John. :)
 

VacuumVoodoo

Member
Messages
1,547
There's one small thing they missed in the DR design which if implemented would make a difference in sound between tube and SS rectification substantially larger.

I'll provide info on this in PM if you're interested. You must promise you won't pass it on to R.S. It's just too basic :);)
 

VikingAmps

Member
Messages
391
I guess what's interesting to me (or should I say confusing then) is why they chose to call the amps "Rectifiers" when in effect (I'm assuming here) that any 100 watt, tube rectified amp would be a "dual rectifier" and any 150 watt, tube rectified amp would be a "triple rectifier". I guess the "dual" they were going for was the switching of solid state rectifier to tube- although that's lost on the "triple" becasue you are really only dual rectifying (tube or SS) three channels? I guess it's really all semantics.

Thanks for all the great info! I've just always been curious what the meaning was and I think I get it now.
Its not true at all that any 100 watt tube rectified amp needs 2 rectifier tubes. There are 100 watt amps that use a single rectifier tube. They will sag a bit more than using 2 rectifiers for the same power but thats not necessarily a bad thing. Mesa could have used a single tube rectifier for thier 100 watter but decided on 2 probably for a tighter sound, reliability and perhaps some marketing hype. You gotta admit it looks cool to see a row of 6 or 7 power tubes.
 

Random Hero

Member
Messages
3,331
Its not true at all that any 100 watt tube rectified amp needs 2 rectifier tubes. There are 100 watt amps that use a single rectifier tube. They will sag a bit more than using 2 rectifiers for the same power but thats not necessarily a bad thing. Mesa could have used a single tube rectifier for thier 100 watter but decided on 2 probably for a tighter sound, reliability and perhaps some marketing hype. You gotta admit it looks cool to see a row of 6 or 7 power tubes.
Or 9 tubes, in the Triple.
 

jessekates

Member
Messages
156
Thirdly, in the Blue Angel there is one rectifier tube, and it isn't switchable (I think it might have been on the earliest models). But it's still a Dual Rectifier because it uses separate tube (for the power stage) and solid-state (for the preamp) rectifiers. The purpose of this is to guarantee that the preamp has greater headroom than the power stage, so the power stage clips first.
I owned and loved a Blue Angel for about 7 years and never understood why it was called a "dual rectifier" until now. Thanks for clearing that up!
 




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