Rectifer Tubes...What's their purpose?

[Gitfiddler]

Swapped out the original rectifier tube in my Heritage Patriot amp and replaced it with a new JJ and I noticed a fairly dramatic difference in the amp's overall tone.

 

Do recitifier tubes generally have that much to do with an amp's tone??

 

Most builders these days have gone to solid state recitfiers. Is that for reliability or tone?

 

 

Can some of you amp experts chime in on the purpose of the tube rectifier, especially in a point-to-point, handwired amp like the Patriot or other similar amps?

 

 

Thanks.

[H]

The rectifier converts AC wall current to the DC used by the other tubes, capacitors, etc.

 

The big capacitors visible on a PTP amp 'smooth' the pulses of DC from the rectifier to make things more stable for the other components.

 

Some rectifiers are a little more efficient which could increase internal voltages and change the sound a little but your sound mostly comes from the combination of the other components in the circuit.

 

Solid state rectifiers don't need a heater current from the PT and are very efficient. The main difference in audio terms is that tube rectifiers produce the effect known as 'sag', and SS rectifiers don't.

[rockabilly69]

There's a big effect is they are dying, but I don't hear much effect going from one brand to another. Like H said the big caps smooth out the

pulses from the rectifier. My TopHat amp uses a fast /slow switch with a solid state rectifier that simulates the sag of a rectifier tube, and it

does that very well. I like having the choice!

[Gitfiddler]

Thanks for the responses. There might have been more of an impact on tone because of the obviously older rectifier I swapped out. It looked much older than the amp and likely put in by the former owner. The amp sounds crisp and bright with the new JJ.

[High Flying Bird]

Components in the amps power supply have, to me, odd effects on the tone. KBP was telling me some things one day and lights were going off in my head.

[H]

Gitfiddler, it may be worth getting the bias for the power tubes checked if your amp is making a noticeably different sound after changing the rectifier.

[Thundersteel]

On some amps, Mesa for example, there is a switch to choose between tubes or diodes for rectification.

[H]

 

Components in the amps power supply have, to me, odd effects on the tone. KBP was telling me some things one day and lights were going off in my head.

Maybe you have some light-emitting diodes in there, Ron

[Gitfiddler]

 

Gitfiddler, it may be worth getting the bias for the power tubes checked if your amp is making a noticeably different sound after changing the rectifier.

 

 

Excellent suggestion, H! Thank you.

[Hfan]

the amp in question is a Heritage so it has the external test points for bias adjustments, and therefore I suppose, you can test the bias externally if you have a meter, nice feature.

[High Flying Bird]

Maybe you have some light-emitting diodes in there, Ron

Those lights are not near that bright.

[mars_hall]

Rectifiers turn AC voltages/currents into DC. Think of it as supplying a continuous level that can be used by another tube as a reference, which it needs. An analogy would be the sound level difference between tremelo and a straight note; it's either changing or continuous. You can get more work done if what you are trying to pull isn't always changing direction. The solid state rectifier is better at keeping the direction constant.

 

The post about sag tells the best story to note here. A solid state rectifier gives more of an instantaneous and uniform supply of electrons across a continuous power supply curve. This means the voltage seen by the power tubes is pretty much constant. You have to get close to saturation of the tubes (full crank) before warmer harmonic clipping starts to kick in. Saturation occurs when either the highest or lowest voltage the tube can be supplied with during a cycle is approached. If the voltage can't go higher or lower than its supply, it will clip at that point and harmonics will come into play by the squaring of the peaks.

 

A tube rectifier is less reliable and not as efficient at keeping up with the demand for electrons the other amp tubes need to stay out of saturation, those highest and lowest peaks being approached (overdrive). The result is the voltage seen by the other tubes will momentarily drop during the peaks (sag) sending the tubes into a momentary premature saturation (overdrive). Right after the sag at the peak ends, if there is no further demand that the rectifier tube can't supply or keep up with, it recovers and the sound/power curve return to normal non-clipping mode, a phenomenon that otherwise would not take place with a solid state rectifier. This tube rectifier supplied sag adds a degree of warmth most associate with the vintage tube distortion sound.

[Steiner]

Rectifiers turn AC voltages/currents into DC. Think of it as supplying a continuous level that can be used by another tube as a reference, which it needs. An analogy would be the sound level difference between tremelo and a straight note; it's either changing or continuous. You can get more work done if what you are trying to pull isn't always changing direction. The solid state rectifier is better at keeping the direction constant.

 

The post about sag tells the best story to note here. A solid state rectifier gives more of an instantaneous and uniform supply of electrons across a continuous power supply curve. This means the voltage seen by the power tubes is pretty much constant. You have to get close to saturation of the tubes (full crank) before warmer harmonic clipping starts to kick in. Saturation occurs when either the highest or lowest voltage the tube can be supplied with during a cycle is approached. If the voltage can't go higher or lower than its supply, it will clip at that point and harmonics will come into play by the squaring of the peaks.

 

A tube rectifier is less reliable and not as efficient at keeping up with the demand for electrons the other amp tubes need to stay out of saturation, those highest and lowest peaks being approached (overdrive). The result is the voltage seen by the other tubes will momentarily drop during the peaks (sag) sending the tubes into a momentary premature saturation (overdrive). Right after the sag at the peak ends, if there is no further demand that the rectifier tube can't supply or keep up with, it recovers and the sound/power curve return to normal non-clipping mode, a phenomenon that otherwise would not take place with a solid state rectifier. This tube rectifier supplied sag adds a degree of warmth most associate with the vintage tube distortion sound.

 

I really enjoy your electronics perspective mars_hall. A true education without having to travel the long road.

[High Flying Bird]

I really enjoy your electronics perspective mars_hall. A true education without having to travel the long road.

No doubt a, "Thank you Spock," moment. I must have a tube scrotum. I got's plenty of sag these days.....

[Steiner]

No doubt a, "Thank you Spock," moment. I must have a tube scrotum. I got's plenty of sag these days.....

 

Bird - You're your nuts.

[bolero]

rectumfier's...they keep your butt warm

 

no lie: I am frying up 3 ham steaks ass I type this...peameal bacon, in fact

[bolero]

I believe SS rectifier's will slightly increase the amp's power output

 

weber sells copper cap rectifier's that are supposed to simulate/replace a tube rectifer but are more reliable. I had one in a matchless DC30 & it sounded good to my ears

[JAM]

As stated, the rectifier basically converts the AC line current coming into your amplifier to the DC voltages that are needed. It's AC opposite is called an inverter.

 

Swapping the rectifier tubes can change the sound/tone of an amp, sometimes dramatically.

 

Bit of a myth that tube rectifiers are unreliable. SS Diodes are very reliable, and to some, the inference is that tubes are less so. Actually, the tube can last a very long time and those which do fail short of their intended service life do so usually from a manufacturing defect. But actually, if you blow the tube in an amp, it's much easier to replace than it's equivalent solid state component - you just swap them out.

 

Care should be taken whenever swapping rectifier tubes as a 'hotter' tube will effect all the components downstream such as the transformer, which you can overpower.

 

cheers!

 

Jim

[High Flying Bird]

As stated, the rectifier basically converts the AC line current coming into your amplifier to the DC voltages that are needed. It's AC opposite is called an inverter.

 

Swapping the rectifier tubes can change the sound/tone of an amp, sometimes dramatically.

 

Bit of a myth that tube rectifiers are unreliable. SS Diodes are very reliable, and to some, the inference is that tubes are less so. Actually, the tube can last a very long time and those which do fail short of their intended service life do so usually from a manufacturing defect. But actually, if you blow the tube in an amp, it's much easier to replace than it's equivalent solid state component - you just swap them out.

 

Care should be taken whenever swapping rectifier tubes as a 'hotter' tube will effect all the components downstream such as the transformer, which you can overpower.

 

cheers!

 

Jim

Good advice. I don't know much about electronics overall but I spent 15 years as an R&D tech for an aerospace company. I got to work on power supplies with an old school engineer. He told me that you had to know what arena you were working in to understand the consequences. Bob Martin died a few weeks ago. He was a good teacher. Ask questions before blowing out your rectumfryer.

[Gitfiddler]

 

As stated, the rectifier basically converts the AC line current coming into your amplifier to the DC voltages that are needed. It's AC opposite is called an inverter.

 

Swapping the rectifier tubes can change the sound/tone of an amp, sometimes dramatically.

 

Bit of a myth that tube rectifiers are unreliable. SS Diodes are very reliable, and to some, the inference is that tubes are less so. Actually, the tube can last a very long time and those which do fail short of their intended service life do so usually from a manufacturing defect. But actually, if you blow the tube in an amp, it's much easier to replace than it's equivalent solid state component - you just swap them out.

 

Care should be taken whenever swapping rectifier tubes as a 'hotter' tube will effect all the components downstream such as the transformer, which you can overpower.

 

cheers!

 

Jim

 

 

 

Thanks for the clear explanation, JAM!!

 

I knew I wasn't imagining a dramatic tonal change when swapping the rectifier tubes.

Now the first thing I'm going to do is put the originals back in their respective amps...and crank it up!!

[rockabilly69]

The dramatic difference is usually only heard when the rectifier tube is failing:) I've had this happen more than once!

[Gitfiddler]

 

The dramatic difference is usually only heard when the rectifier tube is failing:) I've had this happen more than once!

 

 

Yep, that's why I've got a new Sovtek GZ34 on the way.

[HANGAR18]

When I read this thread, I thought to myself that that there is enough talent within the HOC to produce a Heritage Owner's Club brand of guitar amplifier.

 

When ya'll were talking' about the combination of solid state and tubes working together, I thought to myself, "So that's why Alex Skolnick was trying to produce a signature model amp with both solid state and tubes".

 

Then I found this video (below) and thought, "If a Heritage Guitar Signature Model Artist comes up with his own amplifier, would that be the same thing as the HOC producing their own amplifier?"