Is your amp really a tube amp?

[DaveyF]

In the new Absolute Sound, JV comments on the new Siltech amp that is a hybrid tube/ss amp. Apparently it is a game changer.
Anyhow, looking at many of the current crop of tube amps, it would appear that many/most of them use a ss power supply and many other ss parts.
This is something that has been evident in tube amps and tube preamps for some time now....
My question is how much of today's tube gear is truly all tubes...tube power supply and tube front end, etc. To the more technically inclined, I ask what is the
definition of a "tube amp"?

 

[rbbert]

Only slightly off-topic, but it's hard to take seriously (any more) Valin or Harley calling something a "game changer". Between the two of them isn't this about the tenth "game-changing" component in the last couple of years?

And they haven't even reviewed (yet) something like Steve's Shunyata power supply/conditioning setup; just imagine what hyperbole they'll need to use to describe that!

 

[DaveyF]

Only slightly off-topic, but it's hard to take seriously (any more) Valin or Harley calling something a "game changer". Between the two of them isn't this about the tenth "game-changing" component in the last couple of years?

And they haven't even reviewed (yet) something like Steve's Shunyata power supply/conditioning setup; just imagine what hyperbole they'll need to use to describe that!

Interesting observation and one that I concur with. It seems that a lot of reviewer's these days see NOTHING whatsoever wrong with any of the gear that they review. Hyperbole is the order of the day.

 

[JackD201]

The "purist" will say a "true tube amp" will have tube input/driver, tube power and be tube rectified. Personally, I consider the first two to be enough to be considered a true tube amp as opposed to it being considered a hybrid.

 

[Phelonious Ponk]

The "purist" will say a "true tube amp" will have tube input/driver, tube power and be tube rectified. Personally, I consider the first two to be enough to be considered a true tube amp as opposed to it being considered a hybrid.

This is the way things are defined in the world of guitar amps, FWIW. tube rectifiers have their value, and their proponents, but an amp is not considered "hybrid" unless one of the main sections - pre or power - is SS.

Tim

 

[DaveyF]

The "purist" will say a "true tube amp" will have tube input/driver, tube power and be tube rectified. Personally, I consider the first two to be enough to be considered a true tube amp as opposed to it being considered a hybrid.

Interesting, Jack. So why is that not more tube amps (in the audio world and NOT the pro audio world, Tim) do not use a tube rectifier...and it seems have gone away from tube inputs/drivers?
BTW, my guitar amp has the ability to have a tube rectifier in the output or a ss rectifier. Apparently the ss gives off slightly more power at the cost of purity.

 

[microstrip]

In the new Absolute Sound, JV comments on the new Siltech amp that is a hybrid tube/ss amp. Apparently it is a game changer.
Anyhow, looking at many of the current crop of tube amps, it would appear that many/most of them use a ss power supply and many other ss parts.
This is something that has been evident in tube amps and tube preamps for some time now....
My question is how much of today's tube gear is truly all tubes...tube power supply and tube front end, etc. To the more technically inclined, I ask what is the
definition of a "tube amp"?

Davey,

Are you referring to the Siltech SAGA? If so it is really a game changer- it uses many battery power supplies, a control unit , a tube voltage amplifier and a current power buffer - as far as I know each using different type topology. Not easy to class in conventional categories.

 

[microstrip]

The "purist" will say a "true tube amp" will have tube input/driver, tube power and be tube rectified. Personally, I consider the first two to be enough to be considered a true tube amp as opposed to it being considered a hybrid.

I agree with this perspective - a pragmatic way of considering mainly the devices that have gain. Many units considered as pure tubes have solid state elements in the biasing circuits.

 

[JackD201]

If I'm not mistaken, they give the same power but the SS is less likely to sag. So it's more about being able to provide enough DC when needed for peaks. I'm not so sure if there is a big difference when working within nominal range. The only tube rectified amps I own now are my 300B SETs. I guess it is just assumed that I have to have speakers that can play well with only 8 watts or so. In other words, specialized speakers. With amp builders faced with the likelihood that their amps will be driving speakers with less sensitivity and less linear impedance, anything that would lessen sagging, which sounds like compression, makes sense. Working backwards from targeted output say, 100wpc, imagine what a tube rectified power supply would look like. Now imagine something an amp with output like a Sigfried or a REF750.

If I'm reading you right, I think you are saying todays tube amps are starting to sound more like SS amps and that this might be one of the reasons. I suppose that could be partially true but my bet is that it is more because of the current production tubes available. In the meantime SS on the whole has become far more liquid than just 10 years ago. Like with tubes, my bet is that this is in large part due to the faster and more stable transistors today.

 

[DaveyF]

Davey,

Are you referring to the Siltech SAGA? If so it is really a game changer- it uses many battery power supplies, a control unit , a tube voltage amplifier and a current power buffer - as far as I know each using different type topology. Not easy to class in conventional categories.

Micro, I am referring to the SAGA. JV raves about it...however,these days he raves about everything he reviews. I have not heard this amp so I cannot say how I would like it, BUT like I said above, JV says it's a game changer!

Jack, an amp that puts out say 100 watts/ch with a tube rectified supply would be very interesting, I wonder how that would sound A 750/watt ch amp would be even more interesting....BUT I guess we're not likely to find out, LOL.
However, I was not specifically talking about the current sound of tube amps and their similarity in sound to current ss designs, although you bring up a good point.

 

[mep]

Interesting, Jack. So why is that not more tube amps (in the audio world and NOT the pro audio world, Tim) do not use a tube rectifier...and it seems have gone away from tube inputs/drivers?
BTW, my guitar amp has the ability to have a tube rectifier in the output or a ss rectifier. Apparently the ss gives off slightly more power at the cost of purity.

Same reason that ARC doesn't use them in their tube amps. I know that once upon a time you thought that your D-70 MKII had a tube rectifier until I told you that what you thought was a rectifier (a 6550 tube) was actually a series regulator for the B+. ARC used this scheme in their power supply of their tube amps for many years. If you want a stiff power supply that will enable your tube amp to have deep tight bass, you use a SS rectifier. They don't sag under load which is desirable in a guitar amp but is not desirable in a tube amp. I can't think of a single high-powered tube amp that uses a tube rectifier. ARC, VTL, CJ, VAC, Jadis and most others don't use tube rectifiers.

 

[microstrip]

Typical tube rectifiers are much less efficient than the usual power supply diodes as they have high plate resistance compared to SS diodes. This high resistance will also affect the regulation of the power supply, and they can supply only limited values of current. The main advantage is that they emit less noise than SS diodes around the switching point. They can be considered for low power class A applications, where current will be almost constant - as in the Lamm ML3, that includes six tube rectifiers in the power supply. In class AB or B guitar amplifiers they will probably create some nice clipping distortion, contributing to characteristic sound of the amplifier.

As usually, it is not only the components that count - most of all it is how designers use them.

 

[LL21]

Typical tube rectifiers are much less efficient than the usual power supply diodes as they have high plate resistance compared to SS diodes. This high resistance will also affect the regulation of the power supply, and they can supply only limited values of current. The main advantage is that they emit less noise than SS diodes around the switching point. They can be considered for low power class A applications, where current will be almost constant - as in the Lamm ML3, that includes six tube rectifiers in the power supply. In class AB or B guitar amplifiers they will probably create some nice clipping distortion, contributing to characteristic sound of the amplifier.

As usually, it is not only the components that count - most of all it is how designers use them.

I presume based on your description above, the 2 6CA4 and 1 6X4 rectifier tubes for my Zanden DAC are more than sufficient given the level of current they are being asked to deliver? I will say, re-tubing this past weekend (my old tubes had 6,000 hours on them minimum and were just starting to fade in the bass/attack)...has made a big improvement. Bass slam and overall dynamics...but also the 'blast' of a trumpet', or the soar of a soprano all have far great separation, control and 'attack'.

 

[mep]

I presume based on your description above, the 2 6CA4 and 1 6X4 rectifier tubes for my Zanden DAC are more than sufficient given the level of current they are being asked to deliver? I will say, re-tubing this past weekend (my old tubes had 6,000 hours on them minimum and were just starting to fade in the bass/attack)...has made a big improvement. Bass slam and overall dynamics...but also the 'blast' of a trumpet', or the soar of a soprano all have far great separation, control and 'attack'.

If there is a "proper" place to use tube rectifiers, it would be in a low voltage (comparatively speaking), low current situation which describes most tube preamps and linestages. Getting back to the title/premise, companies that call themselves "pure tube" sort of get on my nerves if their rectification and regulation is all SS.

 

[Phelonious Ponk]

If I'm not mistaken, they give the same power but the SS is less likely to sag. So it's more about being able to provide enough DC when needed for peaks. I'm not so sure if there is a big difference when working within nominal range. The only tube rectified amps I own now are my 300B SETs. I guess it is just assumed that I have to have speakers that can play well with only 8 watts or so. In other words, specialized speakers. With amp builders faced with the likelihood that their amps will be driving speakers with less sensitivity and less linear impedance, anything that would lessen sagging, which sounds like compression, makes sense. Working backwards from targeted output say, 100wpc, imagine what a tube rectified power supply would look like. Now imagine something an amp with output like a Sigfried or a REF750.

If I'm reading you right, I think you are saying todays tube amps are starting to sound more like SS amps and that this might be one of the reasons. I suppose that could be partially true but my bet is that it is more because of the current production tubes available. In the meantime SS on the whole has become far more liquid than just 10 years ago. Like with tubes, my bet is that this is in large part due to the faster and more stable transistors today.

Yeah, warm, fuzzy compression. Can be a wonderful thing in a guitar amp. I can't imagine what purpose, other than philosophical purity, that it could serve in a high fidelity amp aimed at reproducing recordings.

Tim

 

[microstrip]

I presume based on your description above, the 2 6CA4 and 1 6X4 rectifier tubes for my Zanden DAC are more than sufficient given the level of current they are being asked to deliver? I will say, re-tubing this past weekend (my old tubes had 6,000 hours on them minimum and were just starting to fade in the bass/attack)...has made a big improvement. Bass slam and overall dynamics...but also the 'blast' of a trumpet', or the soar of a soprano all have far great separation, control and 'attack'.

If there is a "proper" place to use tube rectifiers, it would be in a low voltage (comparatively speaking), low current situation which describes most tube preamps and linestages. Getting back to the title/premise, companies that call themselves "pure tube" sort of get on my nerves if their rectification and regulation is all SS.

Preamplifiers and DACs are low current class A devices - very appropriate for using rectifier tubes. However anyone having equipment using them should remember that they need periodic replacement, as every tube. Most cheap tube testers can measure them adequately.

 

[LL21]

I presume based on your description above, the 2 6CA4 and 1 6X4 rectifier tubes for my Zanden DAC are more than sufficient given the level of current they are being asked to deliver?...

If there is a "proper" place to use tube rectifiers, it would be in a low voltage (comparatively speaking), low current situation which describes most tube preamps and linestages. Getting back to the title/premise, companies that call themselves "pure tube" sort of get on my nerves if their rectification and regulation is all SS.

Preamplifiers and DACs are low current class A devices - very appropriate for using rectifier tubes. However anyone having equipment using them should remember that they need periodic replacement, as every tube. Most cheap tube testers can measure them adequately.

Thanks Gents!! Good to know. Nice to learn.

 

[zztop7]

Loving home available to abandoned Mullard 5AR4 tubes / relabeled Mullards will also be well taken care of.

zz.

 

[mep]

Loving home available to abandoned Mullard 5AR4 tubes / relabeled Mullards will also be well taken care of.

zz.

The Mullard GZ-34 is a great tube and will provide decent bass in tube amps up to 60 watts. The other great thing is that they are known to last for 30 years.

 

[DaveyF]

So, are we saying that tube rectification is desirable in only low powered applications?
If so, would it not be possible to build a higher powered tube rectified amp that does NOT show signs of sagging under draw and at the same time offers the benefits of tube rectification? Lamm uses tube rectification on their Lamm 3's at low power, probably for a good reason, as IMHO these amps are superb.