Which is Better Sound From High Power: Single Tube SET or Parallel Tube SET?

Ron Resnick

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There are single tube SET amplifiers, such the Wavac and the Audio Music (833 tube) and the NAT Magma New SE (GM-100 tube), in the 120 watt output range and there are parallel SET amplifiers, such as the MastersounD PF100 (four 845s), putting out 120 watts.

What are the sonic pros and cons of a high power single tube SET amplifier versus the same output level in a parallel SET amplifier?
 

DSkip

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There are single tube SET amplifiers, such the Wavac and the Audio Music (833 tube) and the NAT Magma New SE (GM-100 tube), in the 120 watt output range and there are parallel SET amplifiers, such as the MastersounD PF100 (four 845s), putting out 120 watts.

What are the sonic pros and cons of a high power single tube SET amplifier versus the same output level in a parallel SET amplifier?

I've always been told that when you go parallel, you lose some of the SE virtue. Honestly, for years it steered me away from PSE amps. The Evolution 845 completely proved me wrong as I found no issues with a lost SE sonic identity and instead found much more ease to the presentation. I can also say that my favorite overall amp from MastersounD is the Dueventi - a parallel SEP amplifier. It might be the best el34 amplifier I've heard.

I think in either design the overall sound will boil down to how good the transformers are first and foremost.
 
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Believe High Fidelity

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Well there are the virtues of the tube design and the characteristics of the tube itself on the design. So with that in mind if you hear the tube and like say a 300B or 845 then having them at the top of their design in parallel wouldn't matter because you already like that flavor of tube.

Simpler circuits with less tubes favor a much better sound. Less stages (2-3) so I am pro single tube vs parallel when applicable. However, on flavor the 833 is not my favorite tube and its designs seem to always be compromised to have higher output. The NAT GM 100 is the better platform amongst all the listed options. Linearity on the GM favors this as well.

Non sonic wise the GM is not a garden variety tube so getting replacements may prove either a challenge or just much more costly.
 

KeithR

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agreed- i think the tube used matters more than SET vs PSET. many of these big transmitter tubes weren't meant for audio so require different implementations

ps. I loved that Dueventi SEP as well - one of the best bargains in audio. wish i would have kept mine!
 

Speedskater

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The reason for SET amplifiers is euphonic colorations. So depending on the loudspeakers it comes down to preference.
To me the 'better sound' phrase implies a more accurate sound. I think that a more pleasing sound is what you are looking for.
 

DSkip

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The reason for SET amplifiers is euphonic colorations. So depending on the loudspeakers it comes down to preference.
To me the 'better sound' phrase implies a more accurate sound. I think that a more pleasing sound is what you are looking for.

I don't agree, but I can see where many view it that way. To me a SE design has a purity to the signal, not a coloration. It isn't about tone as much as it is the way the music is presented.
 

Empirical Audio

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The reason for SET amplifiers is euphonic colorations. So depending on the loudspeakers it comes down to preference.
To me the 'better sound' phrase implies a more accurate sound. I think that a more pleasing sound is what you are looking for.

My SET amps, with one tube, sound just like my 1000W SS monoblocks, except better bass and more 3-D. No euphonia there. This result is highly dependent on the tubes and the mods to the SET amps, as well as the speaker efficiency. Output transformer is also critical. My SET monoblocks were good prior to mods. Now they are spectacular.

Steve N.
Empirical Audio
 
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ddk

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There are single tube SET amplifiers, such the Wavac and the Audio Music (833 tube) and the NAT Magma New SE (GM-100 tube), in the 120 watt output range and there are parallel SET amplifiers, such as the MastersounD PF100 (four 845s), putting out 120 watts.

What are the sonic pros and cons of a high power single tube SET amplifier versus the same output level in a parallel SET amplifier?

Distortion! You give up the sonic purity of a SET.

The reason for SET amplifiers is euphonic colorations.

That's your definition Kevin, no one's into euphonic coloration here.

david
 

andromedaaudio

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I never got the SET thing , i never owned a lamm, so who knows.
What i do believe is that in the right speaker amp match tubes are a faster amplyfing device .
From all the SS i ve owned id say the main factor is is that they are slower.
Doesn't always is a bad thing on certain music it may sound more real then tubes due to is relaxter vibe
 
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Empirical Audio

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Single-tube SET amps have the advantage that there is no compensation for tubes in parallel. Just like transistors, when you have support circuits that force the two or more active devices to share the current, distortions occur. The output curves for any two devices are not exactly the same, particularly tubes.

Some output tube types are better than others, but not so much because of the size, voltage or current or the fact that it was used for RF transmitter. The SQ of these is more a function of the manufacturer that fabricated the tube, the materials used, the design and whether it was "binned" for different performance levels. Just like most tubes, the performance is related to all of these factors. Some tube types that were only made in the USA by RCA, Sylvania, etc.. don't perform as well as similar but different tube types made in Germany or USSR/Russia for instance. These US tubes were primarily designed for HIFI gear and TV's. This is why it is critical when designing tube equipment to be familiar with the high-performance tubes of different types available in Europe and Asia, so you can pick optimum types for each circuit. A case in point is US 12AT7 12AX7 6SN7 versus German 6922 or Russian military 6N8S. Many Russian tubes were used in aircraft and Nuclear power plants until almost 1990. They had to be designed to be really durable and very high-performance at the same time, so these can be amazing for audio.

Steve N.
Empirical Audio
 
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Empirical Audio

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I never got the SET thing , i never owned a lamm, so who knows.
What i do believe is that in the right speaker amp match tubes are a faster amplyfing device .
From all the SS i ve owned id say the main factor is is that they are slower

If they are slower, the amps don't have good power delivery to the tubes or they have the wrong tubes in the sockets. Tubes that come with amps are usually sub-par in order to make them more affordable. The first thing you do is mod the amps and replace all the tubes.

Steve N.
Empirical Audio
 

Ron Resnick

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. . .

ps. I loved that Dueventi SEP as well - one of the best bargains in audio. wish i would have kept mine!

It is 20 watts? On what speakers did you use it?
 

Ron Resnick

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Distortion! You give up the sonic purity of a SET.

. . .

But which way does that cut? Some would argue that, especially in the lower frequencies, a single tube SET exhibits high distortion.
 

Ron Resnick

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I think one of us should buy the MastersounD PF-100 PSET and the AM Audio 833S Ultima SET and compare them directly. Or, for a more apples to apples comparison, someone should buy the four 845 tube PF-100 and a single 845 tube amp by MastersounD.

Tang? ;)


* * *


PS: Okay, I admit it. I want a MastersounD PF-100 AND an AM Audio 833S Ultima!
 

pweg

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Hi Ron

i had the AM in my system for a demo a year or two ago. In my system it was very unimpressive. If i had taken that as the sound of SET then i would have given up there and then.

In my system at the time it sounded very detailed and fast, lean and with an exposed top end. It didnt sit well with me. am amp.jpg
 

andromedaaudio

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If you re speakers are to low sensivity and or have a rather difficult low imp curve , the amps and certainly SET tube Amps have problems controlling your woofers.
Results in hearing no bass , and because a natural reaction is to increase the volume you end up with a enhanced mid treble sound.

It could be also the case here
 

pweg

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Jun 8, 2014
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u may be right there ...... but i ended up with these amps and they have the best bass ive ever had in my room - same speakers - PSET though, not SET
 

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853guy

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Hello gents,

I can’t nor will I try to offer any attempt at answering the question directly, as I’ve never compared a SET of a certain wattage with that of a PSET of the same wattage, given the variables between the two are too great.

I can say this:

I have never liked big bottle tubes, including the 805, 845, 211, GM70 and 833 - at least not in any of the implementations I heard them.

I have also never liked PSETs using any tube (big or small), or push-pull amps for that matter (unless we’re talking guitar amps).

So despite a well-entrenched bias against big bottle tubes and parallel circuits in general, and a growing conviction that no big bottle amp or parallel topology would ever meet my criteria for ownership, that all changed when I heard an amp that used a tube that was new to me, the RCA 813, a big bottle tube of which two were used in parallel, driven by a single RCA 814. That amp is now my favourite by far.

That’s not to say I’ve changed my mind about big bottles or parallel circuits in general. Just that single variables in isolation usually tell us nothing about how those variables react and interact when brought together. Again, implementation trumps topology, and topology trumps parts selection, at least in my experience.

Best,

853guy
 

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