I keep receiving emails from visitors asking me about my views regarding the GM70 vs. 6C33C. I am clearly not in a position to provide any EXPERT opinion because of two reasons. First, I never had a properly built GM70 in my disposal. Second, I hate DIY people, along with their BS interests…

From time to time the GM70 idea comes to me but there is always something the turns me off. The most important is power. People who read my site know that I do not believe in SETs but rather in the DSETs. To have 30W-40W is good but what for?

To use high voltage, 150kg pound monster-amp and to use it with a 20dB voltage divider is probably not a good idea. If a person is stupid enough to use low sensitively speakers that would need those 30W-40W then the person is juts stupid and a “better” amp will not help him…. The only thing that left are usually lower sensitivity LF sections of DSET but still… Mass, heat, cost, high plate impedance, huge transformer for LF section and it is only 40W. Not a lot of reimbursement for the efforts.

Sound? I do not know. I heard 4-5 amps around the GM70 and all of them were crap. I do not think that it was problem with GM70 but rather the amps were not serious.  There are some interesting private, “no holds barriers” implementation around GM70 about wish I have heard but I personally did not hear those amplifiers and the most important those installations.

6C33C is cheap, flexible, easy implementable, very good sounding with fix bias and a proper driver, low voltage and low plate impedance. I find the 6C33C is a quite nice nice for ~9W-12W SET.

Is 6C33C better then GM70? I do not know. I defiantly know that to implement the GM70 and 6C33C at the same level of max performance for each tube would requite very different level of affords. Would the result be justifiable? I do not know. I hope to learn about it sometimes.

Still, following my unavoidable rule:

http://www.goodsoundclub.com/TreeItem.aspx?PostID=432

I would like to be able to identify what the 6C33C or the GM70 does wrong before to consider anything else, though I know that I usually do not like sound of the “large” high voltage tubes: they work “somehow OK” only with the initially dead speakers.

I personally do not look at the GM70 direction but would be happy to audition somebody else’s efforts. The only tube that I might be trying in Melquiades would be YO186 for MF DSET but my motivations are very-very low and so far what 6C33C does perfectly satisfys me. If you have any “special” experience with GM70 (not with 211/845) then let me know.

Rgs,
Romy the Cat

Lamm has been talking about his GM70-based amp for many years, buttering the subscribing to his speeches public. I do not know what the status in there but I would not expect anything relatively interesting. There are many objective reasons why I do not. Lamm latterly switch his products orientation and target market to hi-fi mass-market and currently his company unfortunately does not offer sound that it use to. In addition, some mental and psychological aberrations that Lamm obtained since bought into his industry statues, from my perspective, made him impotent to produces any more or less interesting results.

The Soviet tubes? I do not like them. Most of them snickly vulgar, dirty-colored, have no delicacy and no diminutive discrimination, too brutal, very unreliable, have a huge deviation from specification. Russian tubes Sound is like to massage a human body wearing gloves. Each single time when western equivalents was available the Soviet tubes were in deep lost. Not to mention the practically any Soviet tube, very similar to the majority of of Soviet commercial products, are juts the direct copy-cats of the western model.  I know some people who spread propaganda about the superior Sound of Russian tube but if to look deeply then behind their  views there are or mercantile interest, or plane ignorance or, primitive reference points or juts the typical Russian stupidly-imperial nationalism.

I do not have any observations “ in terms of sense”. I do not think that tubes, any of them have their intrinsic sound. All those tubes wee made “as is” and no one cared how them might sound. The GM70 was made to broadcast the Soviet railways regulation signal and not one ever thought that it might be ever used for any serious sound reproduction. In fact I do not think that anyone even made any tubes consciously and deliberately “for sound”. First of all because no one know or knew how to do it. We juts take the selected by different criteria tubes as they are and try to accommodate them for our purposes.

Why the Soviet tubes sound bad? I do not know and I do not think that they NECESSARY sound bad. They sound bad in comparing to their Western equivalents. However Russians made some their own tubes that were not stolen from West or stolen so poorly that it leaded to the creation of own “off the wall” tubes. Those tubes migh “sound OK” but only God knows how they would sound if West would produce the tubes with the identical characteristics.  It would defiantly would be fun to have for those $7 per tube the  Tungsram, Mazda, Mullard, Raytheon or Sylvania made 6C33C… I am sure if the do them then they would be much more interesting then the Soviet 6C33C

Rgs,
The Cat

Genn wrote:

However - you decided to use 6E5Pi to drive 6C33C, and the filed of competition in this case might be higher - including those E810F,  E180F, EL84..  or even 12AT7, or even (probably) WE 437.  Some of them would need higher input, but that is not a problem with pream. Were there any sonic reasons to choose 6E5P?  Or it is just a good engineering fit?

The caT

I always was “concerned” about those large high voltage triodes: 211, 845, GM70….  They kind of different… The 845 always was brutal and not elegant, 210 was elegant but not sophisticated, and the GM70 was sophisticated enough but no one build any serious performing systems with this tube.

Still, all those large over 1000V tubes share the same quality that I head in all of them. Despite of their obvious intrinsic and implementation differences they all share something that I call “elephant sound”.

A couple days ago I heard a 845-based PP, driven by 300B. Even if to forget any randomness of that installation I still had a constant feeling when I was listening that I was geting the “elephant sound” – the sound that develops it’s own pressure without reference to it’s dimensions . To me those amps sound alike an elephant that stays in my leaving room. Suddenly the elephant would like to call me from kitchen and he makes his crazzy scream to attract my attention.  This scream is completely without any proportion to the distance, intentions, result and volume. It is juts a very rough loud and big sound, completely unnecessary in the given context. All 211, 845, GM70 that I heard did it: they created initially large sound and than minimize it's side depends of the input signal. People kind of like it, I do not.

The 6C33C does opposite: it crate a small sizes with small signal and then increase the “size of the elephant in the room" along with it's necessity. The 6C33C do not reaches the “size” of the 211, 845, GM7 but when we are talking about the 211, 845, GM70 size do we talk an it’s side or we talk about a pressure as an evidence of the size? What would describes the elephant on a room: it’s smell, it’s size, or…. the pressure with which the elephant’s ass press a listener to a wall?

To me the sound of 211, 845, GM70 in some ways remind me the sound of Martin Logan Statement.

If heard that monster 3 times and if you have experience with “that” sound then you know what I mean. Defiantly the Martin Logan Statement is too horrible to make this association but in any association there is a reason….

Rgs,
Romy The Cat

Romy the Cat wrote:

I always was “concerned” about those large high voltage triodes: 211, 845, GM70….  They kind of different… The 845 always was brutal and not elegant, 210 was elegant but not sophisticated, and the GM70 was sophisticated enough but no one build any serious performing systems with this tube.

It is not that I am contemplation the GM70 – I relay have no use for such an amplifier - but this event again made me to think about the sound of those high voltage triodes like 211, 845, GM70.

What I feel that those large high voltage tubes trade the brilliance of the details for the size of the presentation. It is not only the “elephant sound” but also the “elephant color”. The elephants are mostly grayish, so the 211, 845, GM70….

Honestly, I do not have my personal experience of teaching the 211, 845, GM70 amps to sound correct. All that I have is an experience of listening of many amplifiers with high voltage triodes. Perhaps they were made improperly, perhaps used wrong drivers, perhaps people did not know how to use those out tubes, or perhaps the OPT were wrong. There are many other reasons why the amps could eat details. I also suspect that to filer out the over thousands volts of GM70 people forced to employ paper and oil capacitors. Paper and oil capacitors dry out sound and eat the sonic nuances very aggressively. They do work in speakers crossovers but they behave very poorly anywhere else. Anyhow, I do not know the real reason I juts know the result.

Now, let look at the installations what I heard the 211, 845, GM70. They all were not the flea power minded installations with “large minded” speakers but they all imploded the flea-capacity acoustic systems. It is well know that I do not have a lot of respect to DIY community and the speakers they produce is even worst then anything else they do.  I have seen people build crazy 1100V amplifiers and run them against the Avantgard Duo, against Verity Parsifal or against the home brewed single driver back-loaded crap. The point is that the people who were impressed with the presentational mannerism of those 845 or GM70 (and partially the 211 that has much less the “elephant effect”) were looking for their amplifiers override the misery of their acoustic systems. The fact that they were loosing the delicacy, details and tonal fragility were completely irrelevant to them because their loudspeaker were not able to handle it to begin with.

Perhaps I am incorrect and there is out there an interestingly performing GM70 amp. There are almost excellent performing 211 amps. So, what is it: voltages? Tube? Implementation? The Moronity of the builder? Go figure…

In the end it is my strong feeling the “size” of playback presentation should be handled ONLY by the effort of acoustic system and it’s relationship with a listening room. The imbed the “largeness” into amplification is wrong…or perhaps less desirable… or perhaps I did not see any good examples how it might be done properly…
 
Rgs,
Romy the Cat

guy sergeant wrote:

I'm sure there are many bad implementations of the 845 and 211. Almost all of the commercially available ones are pretty mediocre. However I have heard good examples of both so I know it can be done.

Actually I did not talk about the “bad implementations” but rather about a common quality of any implementations. Also, the “Jumbo Soundness” of 845, GM70, and in slightly less degree the 211, was moistly perceived by people as virtue, not as a shortcoming. In fact the people who make those amps bravado with the “largeness” of the sound.  As I said above the “big sound” is a virtue of acoustic system not an amplifier….

guy sergeant wrote:

I've yet to hear an impressive 6C33 amp so it wouldn't be my first tube of choice but I'm sure such an amp can exist.

Try the old version of Lamm ML2, you might learn a lot from that sound. I did.

guy sergeant wrote:

I find it amusing when people talk about the sound and character of different tubes when most of what they are listening to is the sound of the power supply attached to them. How you can conclude that this tube sounds 'grey' or that tube sounds 'big' is beyond me. Its like trying to describe the sound of a drive unit without reference to what enclosure it is used in.

Actually when I refer to “gray sound” I did refer to PS, didn’t I? I also was under presumption that when people built their SETs they use the PSs that benefit the given design. Still, I personally did not play with the “large triodes” and whatever I was able to heard form those amps I accept “as is”.

guy sergeant wrote:

Keeping power supply considerations constant, I am currently enjoying using the often overlooked small DH triodes like the 26, 12, 10Y and 71 as line stage or input/driver stages (particularly when choke loaded or transformer coupled) These are all preferable to my ears to the more commonly used and 'modern' higher mu tubes.

If you prefer the specific tubes in context of the keeping the “power supply considerations constant” then why do you “find it amusing when people talk about the sound and character of different tubes”?  It is not the question that requires an answer but juts a rhetoric point of inconsistently of judgments….

The caT

I have to tell you something: I do not believe to audio people. Whatever they say has some freakish twist of desire to present the sings in a certain way instead of witnessing and experiencing the thighs as they are. This is one of the reasons why I generally despise the DIY community: they are incredibly boring in their everlasting hobbysm.

I also hardly believe myself is I have no reasons to know the things defiantly. Above I make a bunch of the observation about the 845, 211, GM70 but I never had any of them in my listening room. Since I have seen very few people who preach the playback system and sound reproduction from the positions that I consider “serious” then what evidence I have that those somebody else’s 845, 211, GM70 amps meant to be “serious”? Yes, it is very much correct that my comments above about the powerful triode were based on bad examples or heard in context of bad installations. So they should be understood appropriately. 

It is very difficult to talk about the soldering people about sound. For instance today I read a witnessing of Nicholas Chua about his observations regarding his GM70 amplifiers:

http://diyparadise.com/nikcgm70.html

I like what he did  more or less and what he wrote. In the end he mentioned a little about his perception of the GM70 sound. That part I got different:

Nicholas Chua wrote:

The Sonics of the amp I would not lie to you, it is great with lots of potential. Feels like a very powerfully 300B and 2A3 amp. It has the nice midrange of the 300B but with the balance tonal of the 2A3. Bass control is excellent here and the amount of bass that can be pump out is insane for a SE amp;

What? What I experienced the properly implemented DSETs do deliver insane bass, not juts insane but absolutely unreachable by any other topology. Yes 300B never has bass but it also never has anything else beside 3-4 octaves on the middle. So did Nicholas discover a good bass with GM70 or he discovered a better bass then 300B?

Nicholas Chua wrote:

there is more high frequency extension with this amp then my 300b amp.

Good grief! A telephone has more HF then 300B!!!

Nicholas Chua wrote:

What I like in particular is that at low volume and high volume the sonic character is the same.

Actually it is very interesting quality. But the very next question I would ask what kind loudspeakers Nicholas uses. Usually the sonic character falling apart at high volume because the 300B and 2A3 die driving sub 100dB sensitively. 35W of the GM70 would defiantly help. The 350W of the SS A/B PP would help also… :-)

Nicholas Chua wrote:

This trait shows the control and power sufficiency of the amp to control the speaker when both posh listening and the wild rocking head banging volume levels is played. The amp plays both rock and other music well. Ziggy Stardust by David Bowie plays now with me rocking in the middle.

No comments…

Nicholas Chua wrote:

Because of good bass control, double bass plays with great authority. The expansion of the double bass is now very apparent like the how it should sound when you stand/sit 2meters away. Normally in most amps, the double bass is the often miss played instrument where the sound is muffled, not there at all, worst the box is heard but not the string being plucked.

I was under impression that with 140R on plate of 6C33 is possible to get much more interesting bass. Taking about the DSET…. The single channel of Melq will have 15000uF in B+. I wonder how mach space this capacitance would take if it were for 1500V and how many extra turns the amp would have in the output transformer in case the GM70.

Nicholas Chua wrote:

New World Symphony Largo LP Brass sections did not lack the speed and timbre associated with SE amps but it is noted that it is still slower than it should be. Because of the non-feedback the speed is not compromise where feedback tends to muddle with the speed as some of the signal is feedback to input thus slowing the sound. But with all SE amps there is more swing in orchestra pieces.

Honestly I did not understand it.

Nicholas Chua wrote:

Separation of the instruments seems to be good too and there clear audible distinct between instruments being played not just a sound wall.

Is it after the 300B? I think the same effect would be if Nicholas would drive his speakers from 8-track car radio – it is the 300B is meant for…

Anyhow, I certainly did not mean to mock the Nicholas’s view but I juts do not see so fat the credible views of the GM70 builders. If someone feel that they have something to say regarding the SOUND of the GM70 vs. 6C33C then feel free to do so.