Is your amp really a tube amp?

[rbbert]

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.

Of course, there are many "different" Mullard GZ34's...

 

[mep]

So, are we saying that tube rectification is desirable in only low powered applications?

Yep.

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 does this on their Lamm 3's at low power, probably for a good reason, as IMHO these amps are superb.

Before reliable non-selenium rectifiers hit the market place, some amp manufacturers used several tube rectifiers in parallel in order to try and stiffen up the B+. They still can't do what a SS bridge rectifier does. There is a reason that the majority of high-end tube amp companies don't use tube rectifiers in their power supplies.

 

[DaveyF]

Yep.




Before reliable non-selenium rectifiers hit the market place, some amp manufacturers used several tube rectifiers in parallel in order to try and stiffen up the B+. They still can't do what a SS bridge rectifier does. There is a reason that the majority of high-end tube amp companies don't use tube rectifiers in their power supplies.

Interesting, so why do you think ARC used a 6550 as a series regulator to stiffen up the B+ for so many years?

 

[mep]

Interesting, so why do you think ARC used a 6550 as a series regulator to stiffen up the B+ for so many years?

The first thing you need to understand is that a series regulator tube has nothing to do with being a tube rectifier. A vacuum tube used as a series regulator keeps the B+ voltage at a constant level. Tube rectifiers change AC into DC. Most voltage regulators used today are all SS. ARC used a 6550 tube as a series regulator because they liked how it sounded in their power supply. There was a period of time when ARC actually got away from using them and I can only speculate that it was due to cost. ARC came back to using them only to later abandon them again in their power supplies of tube amps. I'm pretty sure there are no current ARC tube amps in production that use a vacuum tube series regulator. ARC still uses them in some of their preamps.

 

[DaveyF]

The first thing you need to understand is that a series regulator tube has nothing to do with being a tube rectifier. A vacuum tube used as a series regulator keeps the B+ voltage at a constant level. Tube rectifiers change AC into DC. Most voltage regulators used today are all SS. ARC used a 6550 tube as a series regulator because they liked how it sounded in their power supply. There was a period of time when ARC actually got away from using them and I can only speculate that it was due to cost. ARC came back to using them only to later abandon them again in their power supplies of tube amps. I'm pretty sure there are no current ARC tube amps in production that use a vacuum tube series regulator. ARC still uses them in some of their preamps.

Ok, thanks.

So this does get us back to my original question --which is how much ss stuff is used in today's tube amps? So much that to call them a tube amp may be a misnomer.

 

[microstrip]

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.

Yes, they are mainly used for low power amplifiers - see the ML3 is a 30W amplifier and uses half a dozen rectifier tubes. Surely it is possible to use them for higher power amplifiers, but it will not be practical to built, and cost will be prohibitive.

 

[mep]

Ok, thanks.

So this does get us back to my original question --which is how much ss stuff is used in today's tube amps? So much that to call them a tube amp may be a misnomer.

Here is my take on your question: If an amp uses tubes as input devices and output devices, it's a tube amp. If an amp uses a tube input stage with a SS output stage, it's a hybrid amp. If an amp uses a SS input stage and a tube output stage, it's a hybrid. If you want to say your tube amp is "pure tube," that means it has a vacuum tube power supply in addition to having a tube input stage and output stage.

As to your original question which was "how much ss stuff is used in today's tube amps," the answer is quite a bit. Most all rectification and voltage regulation is SS. Depending on the amp, there can be quite a bit of voltage regulation going on in different parts of the circuit.

 

[microstrip]

The first thing you need to understand is that a series regulator tube has nothing to do with being a tube rectifier. A vacuum tube used as a series regulator keeps the B+ voltage at a constant level. Tube rectifiers change AC into DC. Most voltage regulators used today are all SS. ARC used a 6550 tube as a series regulator because they liked how it sounded in their power supply. There was a period of time when ARC actually got away from using them and I can only speculate that it was due to cost. ARC came back to using them only to later abandon them again in their power supplies of tube amps. I'm pretty sure there are no current ARC tube amps in production that use a vacuum tube series regulator. ARC still uses them in some of their preamps.

Mark,
ARC used the 6550 series regulator only for the input, grids and driver supplies - the B+ was not stabilized! Their current REF250 and 750's also use the same topology using the 6550 as series element regulator controlled by a 6h30. Some models replaced the 6550 series element with MosFETs.

 

[mep]

Mark,
ARC used the 6550 series regulator only for the input, grids and driver supplies - the B+ was not stabilized! Their current REF250 and 750's also use the same topology using the 6550 as series element regulator controlled by a 6h30. Some models replaced the 6550 series element with MosFETs.

Fransisco-Thanks for correcting me. I thought they were used as series regulator for the B+.

 

[microstrip]

Fransisco-Thanks for correcting me. I thought they were used as series regulator for the B+.

Although it could be done, in principle you would need one series tube for each power tube - it would duplicate the number of power tubes of the amplifier. The only amplifier I know about that uses such topology is the Lamm ML2.1 - the second 6c33 is a series element for the voltage regulator feeding the power amplifying 6c33.

 

[Jazzhead]

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 , Have you been lucky enough to hear the SAGA amps, cutting edge for sure . Would you know whether they are of a limited run ?

 

[JackD201]

Micro , Have you been lucky enough to hear the SAGA amps, cutting edge for sure . Would you know whether they are of a limited run ?

I'm pretty sure the price alone will limit the run. PDF is still a bit cryptic. All I could pickup is that it doesn't attenuate (?), uses battery PS for signal gain stages and AC for power stages. There are a lot of hybrid and reverse hybrids in the market. Veloce has already built a pure battery tube/SS hybrid power amp. Jean Hiraga has built all battery/all tube systems (like the one that caught fire ). I'm not so sure what is exactly ground breaking here. Surely not the use of batteries.

 

[flez007]

good point DavetF - since I have found that tubed PSUs have a positive impact in preamp designs, my first experience around this came from a Counterpoint 5000 all-tube preamp!

 

[microstrip]

Micro , Have you been lucky enough to hear the SAGA amps, cutting edge for sure . Would you know whether they are of a limited run ?

No, I just went through the technical literature. As Jack points, none of their main technical points is really an innovation - however grouping all of them in single equipment is really new. And, IMHO, in this audio business, the more important is not the topology, but how you implement it.

The best battery operated equipment I have owned was the German ASR Emitter II exclusive integrated - three very large box power supplies: one stack of batteries for the preamplifier, and two separate power supplies for the power sections. All of them connected through garden hose type umbilical cables. If it was not my love for tubes, it would be high on my list - but I can only imagine it would be a great match with the famous Trinity DAC!

 

[Al M.]

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.

I just purchased last month two massive external BorderPatrol power supplies ($ 2K each) for my 2A3 triode monoblocks, see:

http://parttimeaudiophile.com/2012/10/24/rmaf12-borderpatrol-take-me-away-to-the-living-voice/

(There is a rack where you see four of them, two in the middle and two at the bottom; I have two of them, one for each monoblock. The last picture on the bottom of the page shows the inside of a power supply.)

They are tube rectified, but they absolutely kill the internal SS rectified power supply of my amps in terms of stability and lack of sagging, even though these supplies had already been beefed up considerably over their stock versions. Result: incredibly powerful bass and lack of strain on peaks with more dynamic ease than before, and increased authority of sound. And the tube rectification gives a sonic purity and low noise floor that allows for dramatically increased resolution; this resolution reveals spectacular things I had not thought possible from Redbook CD (under optimal circumstances, the medium now really starts to live up to its early promises from 30 years ago). Review forthcoming.

***

To answer the title of this thread, now my amps really are tube amps.

 

[mep]

I just purchased last month two massive external BorderPatrol power supplies ($ 2K each) for my 2A3 triode monoblocks, see:

http://parttimeaudiophile.com/2012/10/24/rmaf12-borderpatrol-take-me-away-to-the-living-voice/

(There is a rack where you see four of them, two in the middle and two at the bottom; I have two of them, one for each monoblock. The last picture on the bottom of the page shows the inside of a power supply.)

They are tube rectified, but they absolutely kill the internal SS rectified power supply of my amps in terms of stability and lack of sagging, even though these supplies had already been beefed up considerably over their stock versions. Result: incredibly powerful bass and lack of strain on peaks with more dynamic ease than before, and increased authority of sound. And the tube rectification gives a sonic purity and low noise floor that allows for dramatically increased resolution; this resolution reveals spectacular things I had not thought possible from Redbook CD (under optimal circumstances, the medium now really starts to live up to its early promises from 30 years ago). Review forthcoming.

***

To answer the title of this thread, now my amps really are tube amps.

And your amps are really low power tube amps as well which explains why a massive outboard tube power supply works just dandy with them.

 

[JackD201]

Yeah, IME, flea powered triodes with SS rectification is quick but lacks the body and bloom you'd get with a tube PS. That isn't necessarily the case with high powered tube amps.

 

[Al M.]

And your amps are really low power tube amps as well which explains why a massive outboard tube power supply works just dandy with them.

Yes, no disagreement with that.

 

[DaveyF]

good point DavetF - since I have found that tubed PSUs have a positive impact in preamp designs, my first experience around this came from a Counterpoint 5000 all-tube preamp!

View attachment 13103

Fernando, I remember when Mike E was pushing the fact that his new preamp ( The 5000) was featuring the tube power supply. I also remember that it was very impressive to me when I finally had a chance to hear it.

 

[mep]

Fernando, I remember when Mike E was pushing the fact that his new preamp ( The 5000) was featuring the tube power supply. I also remember that it was very impressive to me when I finally had a chance to hear it.

The 5000 actually has less of a tube power supply than the SA-5.1 which came before it.