tube rectifier on 100 watt amp

[mixohoytian]

I'm a bit confused:
from what I've seen on the web, 50 watts and higher is usually ss rectification

do 100 watt amps have to be a combination of tube and ss (like the dual rectifier or the weber mods) ?


are there examples of 100 watt heads that have only tube rectifiers?


Thanks

 

[stratotone]

I'm a bit confused:
from what I've seen on the web, 50 watts and higher is usually ss rectification

do 100 watt amps have to be a combination of tube and ss (like the dual rectifier or the weber mods) ?


are there examples of 100 watt heads that have only tube rectifiers?


Thanks

yeah, they need usually at least two rectifier tubes to handle the output. the mesa dual rect can switch BETWEEN solid state and tube rectification, not both at once.

Pete

 

[glpg80]

the problem with tube rectifiers is that they sag, so guys who play heavier music like metal tend to like a tight and agressive tone and low end with defined mids.

tube rectifiers cant deliver this at high volumes the same way high voltage rated diodes can. its also a big ordeal to have a tube rectifier because if the tube were to short or become deffective it can cause some serious stability issues between the circuits and power transformer. theres always that "chance" which makes designing safe tubed rectified amplifiers more complicated.

also, the point behind a tube rectifier is to rectify the sin-wave AC voltage into a regulated DC voltage. for this purpose...technology has come 20x fold. diodes just do it better and have less noise now in doing it.

it can be done to have both, but its not common, i know mesa does it still but no other amplifier companies are coming to mind. also, you cant have both diode and tube rectified at the same time. i guess i should mention this. someone who loved loud blues music could take advantage of the design in having a TR stage but theres alot more negatives than positives.

 

[stratotone]

The main reason solid state rectifiers replaced tubes is because it was cheaper. Price out a tube socket and a rectifier tube vs less than a dollar's worth of diodes.

Rectifier tubes also have more loss, so you get less B+ voltage rectified with tubes versus solid state. This is also why if you buy a replacement 'solid state' rectifier that goes into a tube socket like the Weber stuff you have to be careful - that extra efficiency and voltage can go past some amps' tolerances and you have a busted amp.

You usually aren't going to get a lot of tube rectifier sag until the amp is CRAZY loud... most of what people consider to be tube rectifier sag on a dual recto is the voltage drop IMHO.

Pete

 

[glpg80]

The main reason solid state rectifiers replaced tubes is because it was cheaper. Price out a tube socket and a rectifier tube vs less than a dollar's worth of diodes.

Rectifier tubes also have more loss, so you get less B+ voltage rectified with tubes versus solid state. This is also why if you buy a replacement 'solid state' rectifier that goes into a tube socket like the Weber stuff you have to be careful - that extra efficiency and voltage can go past some amps' tolerances and you have a busted amp.

You usually aren't going to get a lot of tube rectifier sag until the amp is CRAZY loud... most of what people consider to be tube rectifier sag on a dual recto is the voltage drop IMHO.

Pete

thats what i meant by technology improving 20 fold. they do more, for less. and they also do it quite well.

as for the stability - they depend on the PT for a constant voltage and current source. a tube rectified stage is not as stable at high voltages in the same way as diodes are, so rectifier sag is iminent, but the design of the PT is also a factor when tube rectified stages are mentioned. theres a tone change when tube recified stages not being able to keep up causes a different reaction tone wise. PT sag is more of a feeling thing, the amplifier becomes a hell of alot easier to play and tracks alot slower.

either way you go, the volumes that either of these happen you arent playing the amplifier. the amplifier is playing you!

 

[Death by Uberschall]

the problem with tube rectifiers is that they sag

I wouldn't really call it a "problem", but more of a desired effect when used in modern amps.

It just helps a tube amp seem more elastic, organic and breathe instead of sounding sterile at times. I like 'em, wish more builders still used them.

But the reality is that the solid state diode rectifiers were used because they are cheaper, some what more reliable (I never had a tube rectifier fail though) and provided a higher and more even output from the amp which was a benefit to amp builders, epsecially when they were trying to make them louder.

 

[mixohoytian]

thanks for all the info guys
I don't want metal, I want 60s vibe
I got a jtm 45/100 circuit on an amp and it has ss rectifier...thinking of modding it to get more vintage vibe

the metro amp or other kits for the 45/100 use tube retifiers right?
I saw a mod out there, I forget the name, I'll post it monday
it divides the power between tube and ss
or something like that, so you get the sag tone, but w/ the modern efficiency...

 

[mixohoytian]

ok here it is

if I want the sag on 100 watt amp,
should I try this?

http://kendrick-amplifiers.com/Merchant ... _Code=0802


or just have my tech copy the Mesa's method?

 

[glpg80]

thats not a safe mod, and chances are the tone and sag are REALLY dependent of those large 10W resistors used to limit current to the entire circuit of your amplifier.

either look at a new PT to give you more voltage sag from a company like MM, or have your tech copy mesa's dual rectifier setup.

but never run both at once - theres so many wrongs in that i cant even begin to list them all.

 

[mixohoytian]

thats not a safe mod, and chances are the tone and sag are REALLY dependent of those large 10W resistors used to limit current to the entire circuit of your amplifier.

either look at a new PT to give you more voltage sag from a company like MM, or have your tech copy mesa's dual rectifier setup.

but never run both at once - theres so many wrongs in that i cant even begin to list them all.

Thank you so much
I'll have him refer to Mesa's dual recto schematic

 

[glpg80]

not a problem - keep us updated and tell me what you think in switching between the two, id be interested to hear your opinion