Yeah, single stage SETs are a whole other beast. You need a tube with lots of gain and the plate resistance within reasonable levels, and even then be prepared to not use it for bass duties. Two of my channels use single stage 6e6P tetrodes wired in triode for a gobsmacking 1.5watts and a B+ of just 200Vdc. Super simple circuit and makes great sound for the highs, but those channels are 110db/w/m sensitivity and certainly not a solution for everyone.
SETs and Horns
- Thread starter Al M.
- Start date
Yeah, single stage SETs are a whole other beast. You need a tube with lots of gain and the plate resistance within reasonable levels, and even then be prepared to not use it for bass duties. Two of my channels use single stage 6e6P tetrodes wired in triode for a gobsmacking 1.5watts and a B+ of just 200Vdc. Super simple circuit and makes great sound for the highs, but those channels are 110db/w/m sensitivity and certainly not a solution for everyone.
Voyager - Tron Electric
The Tron Voyager is a unique and very special amplifier, and has been a personal project for Graham for many years; as the concept of an OTA circuit he found both intriguing and challenging. It is a true OTA (One Tube per channel Amplifier). There are only three valves in the whole amplifier...
with emission labs 20B DHT
Nice little amp works with diffrent tubes..happy tuberolling
Link shematics
Some different SET Amps with Emission Labs Tubes more Power..lovely
Link shematics
Some different SET Amps with Emission Labs Tubes more Power..lovely
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For Heights and Mids i woulder prefer SET 6-8 watt like this it Thomas Mayer Design,
a One Stage Tube Amp 6hs5 years ago build for other Forum as DIY Project.
Not for Newbies high B+ Voltage 1300 V, you need a good Power Supply and an excelent Output Transformer keep it simple when you want sound good my opinion.
the only thing is you need 2-3 volts rms at the input of the amplifier to get the maximum output power. or an Step up transformer 1: 2 or 1: 3 at the input of the amplifier.View attachment 75026
Or look at this at his Website when you not want DIY.
Tube of the Month: The 6HS5
Hi! This months tube is a very special type with some extraordinary properties, the 6HS5. This is a quite 'modern' tube, developed in the ...vinylsavor.blogspot.com
For Bass you need more power to control the woofer like this PST Tube amp
Not expensive Tubes i hear it with some Blumenhofer Speakers sounds fantastic.
The advantage of an integrated amp is that if you have multi-way horn speakers you can adjust the volume sensitively to the horn driver.
You also need a pre that can supply enough current for the grid.
My EL34 SET has no driver section at all, as a result it has slightly negative gain but EL34 is not hard to drive in terms of current so you could potentially use any high gain tube preamp. I use a dedicated voltage gain stage before the EL34 amp using 6SL7 gain stage and 6SN7 outputs, this makes for a amp with normal gain. I think the largest advantage is the voltage gain and current amp have totally separate power supplies. Using something like this you could make a customized voltage gain stage for the driver in question as well, I've found this is maybe even more important than the current amp.
Of course I can - and did
The 3rd adds a bit of 'warmth'; a romantic character, just like the 2nd. But to be clear if we're talking about an amplifier that has its 3rd as the primary distortion component, keep in mind its 3rd will be at a lower level than the 3rd will be in an amplifier that expresses the 2nd. So there is a bit of a 'at what level?' thing going on here, which might be tricky to really winnow out. In a nutshell the ear is insensitive to both (when these harmonics are appearing in their native amplifier environments), but these harmonics are the only ones where this is the case. I can't speak to what happens if the 3rd is expressed at the same level as the 2nd typically is, but I can't think of a way of doing that either, since amps with a cubic non-linearity are typically lower in distortion even with the primary component.
If its a class A push-pull design there won't be any crossover distortion at all (unless there is a circuit malfunction). Even in a class AB amp this should be the case. I don't see the author arguing otherwise at that link. The place where so many push-pull amps get in trouble is when they combine single-ended circuits at the input and then convert to push-pull. When both circuits are present, the topology has two different basic non-linearities, the quadratic and the cubic, which algebraically result in some emphasis of pesky higher orders, usually the 5th. Its no wonder that many people prefer SETs to that... you get a bit more romantic sound with an SET. But you can design some pretty simple push-pull amps and not get into this problem with a single-ended input. That fully differential amp I mentioned earlier (makes 5 watts using a pair of EL95s and and a single 12AT7 differential amplifier for a voltage amplifier/driver tube, so three tubes per channel) is an example- it only accepts a single-ended input, but doesn't have that prominent 5th.
Thanks, Ralph. Now I see why you are saying in post #3 that there really is no argument for a SET design.
I'm not sure how much the tech specs and measurements really mean unless you correlate them to actual experience and listener preference. IRL SET amps often provide superior results when used properly.
Also, a balanced component is more complicated... it requires double the parts, and if the opposing parts are not perfectly matched it skews the output in a way single ended does not. So SE requires fewer parts, a less complicated circuit and doesn't depend on tight tolerances and/or matched components.
The benefit of balanced, common mode noise rejection, is of little consequence in a vast majority of home audio systems that use cables a very small fraction of the length often used in pro applications. I sell primarily unshielded single ended line-level cables for this reason, because it's almost never an issue, far less than 1% of the time. I've been sending out such cables for demo for nearly a decade now, so lots of data to back up this claim.
I'd argue in the end, a properly implemented SET based system is actually the optimal choice for 2-channel home audio because it's simpler and fits better psychoacoustically as well. Proof is in the results...
OTOH, I'd acknowledge that if you prioritize a low-efficiency speaker type SET becomes a harder sell and for powering modern woofers, probably not the smart choice. So I'm not saying SET is better, period... but I think in some circumstances it might be.
Also, a balanced component is more complicated... it requires double the parts, and if the opposing parts are not perfectly matched it skews the output in a way single ended does not. So SE requires fewer parts, a less complicated circuit and doesn't depend on tight tolerances and/or matched components.
The benefit of balanced, common mode noise rejection, is of little consequence in a vast majority of home audio systems that use cables a very small fraction of the length often used in pro applications. I sell primarily unshielded single ended line-level cables for this reason, because it's almost never an issue, far less than 1% of the time. I've been sending out such cables for demo for nearly a decade now, so lots of data to back up this claim.
I'd argue in the end, a properly implemented SET based system is actually the optimal choice for 2-channel home audio because it's simpler and fits better psychoacoustically as well. Proof is in the results...
OTOH, I'd acknowledge that if you prioritize a low-efficiency speaker type SET becomes a harder sell and for powering modern woofers, probably not the smart choice. So I'm not saying SET is better, period... but I think in some circumstances it might be.
I used to think that the advantage was how the distortion decreases to unmeasurable at a low power levels, but there are other amps that do that too.
You need Preamp like this..
Innovative Audio Ultrapath Line Stage
Innovative Audio Ultrapath Reference Linestage (4272145447) | Tube-Preamp | Offer on audio-markt.de
Offered is „Ultrapath Reference Linestage“ by Innovative Audio from the category „Tube-Preamp“ on audio-markt.de - the online market place for high-end. The advert with the number 4272145447 ends on 22.02.2025 at 07:09 o'clock.
Fully symmetrical tube line preamp
4 inputs, 2 outputs, options
Extremely puristic signal path with only one amplifier stage
Shunt volume control, potentiometer not in the signal path
Current and voltage regulation with tubes.
Gain: approx. 12 dB Frequency response: 5Hz - 200kHz - 3dB
Tube assembly: 4 * 6H30Pi or PDR in the signal path, 2 * 12BH7 as bidirectional voltage regulator, 2 * 6C19 single triode as high-current voltage source
Trust me the best dynamics i ever heard
These are common myths about balanced line operation. If you use differential circuits you don't have twice the components. Matching is helpful- that much is true. But that's something the manufacturer deals with, not the end user. As far as the benefit of use in the home, you get the benefit of balanced lines/balanced operation even if the interconnect is only six inches long. What we're talking about here is
1) artifact of the cable- if you've auditioned single-ended cables and heard a difference, you know what I'm talking about
2) ground loops- everyone has them, but if they don't get amplified they don't affect the background
3) yes you can run longer cables; this is nice if you have monoblocks and want to keep your speaker cables short; doing so gets you greater resolution than long speaker cables and short interconnects
4) fully differential circuits benefit from being more resistant to power supply noise
5) fully differential circuits have a theoretical 6dB less noise per gain stage. How close you get to that 6dB is mostly about how good your constant current sources are.
6) Common Mode Rejection is helpful since if noise (usually hum) is impenged on the interconnect, it gets rejected at the input (whether that's a phono input, preamp or amplifier); this translates to 'blacker background'.
There are, and interestingly, a number of the things that cause distortion in a class D result in lower ordered harmonics. So they can sound surprisingly tube-like.
Interesting preampYou need Preamp like this..
Innovative Audio Ultrapath Line Stage
One Stage Preamp 6H30 Tubes (2 paralell chanel)you can drive 20 m Cable to Active Speaker,or kick in the Grid.Innovative Audio Ultrapath Reference Linestage (4272145447) | Tube-Preamp | Offer on audio-markt.de
Offered is „Ultrapath Reference Linestage“ by Innovative Audio from the category „Tube-Preamp“ on audio-markt.de - the online market place for high-end. The advert with the number 4272145447 ends on 22.02.2025 at 07:09 o'clock.www.audio-markt.de
Fully symmetrical tube line preamp
4 inputs, 2 outputs, options
Extremely puristic signal path with only one amplifier stage
Shunt volume control, potentiometer not in the signal path
Current and voltage regulation with tubes.
Gain: approx. 12 dB Frequency response: 5Hz - 200kHz - 3dB
Tube assembly: 4 * 6H30Pi or PDR in the signal path, 2 * 12BH7 as bidirectional voltage regulator, 2 * 6C19 single triode as high-current voltage source
View attachment 75060
Trust me the best dynamics i ever heard
In many/most situations I agree.
Which also sort of points to the gain structure of the system, which is probably much more important than a lot of people realise. Amplifying the small source signal more than it needs then attenuating it more than a little, or even more than once is a recipe for degrading sound quickly.
Two things in my playback I have been very careful to optimise: gain structure; noise. Very loud listening with all my sources is with about 4dB-10dB of total attenuation in my case via a Slagle silver autoformer at the output to the preamplifer (which is technically perfect in this situation - not necessarily so for all applications). I also have zero audible noise even with my head in the horns, so micro-dynamics are unhindered.
Some SET amps are lower gain and some need more input voltage for maximum output than most 'traditional' SS and hybrid amplifiers and depending on the remainder of the system a preamp with different gain may be required. This is not exclusive to SET amps, but I prefer to build the the best sounding amplifier I can and then feed it whatever voltages are required via the preamp. My sources all are low output circa 1V-1.25Vrms and my amps are high input, then accounting for well recorded music with high dynamic range (an extra say 6dB) I found in the end that 8x gain (18dB) for the preamp is what suited my system and set about finding the best high gain, low output impedance, high current (also specific requirements for my playback - not necessarily for others) preamp to perform this task.
Why is this important? Well, if you are attenuating significant amounts, particularly with some kind of resistive device (eg. potentiometer, ladder or series resistors, chip) or even digital in software, odds are that you can improve sound just by reducing gain somewhere in the system. I listen at 11 o'clock on the volume knob...listening at 9 o'clock would be worse...6 o'clock I do not even want to think about. Listening at 12 o'clock and needing to go to 13 o'clock would be a travesty. This is a long-winded way of saying that swapping out amplifiers often changes the gain structure of the system and that in this situation the changes heard are not neccesarily entirely attributable to that amplifier, but perhaps may be due to the attenuator, perhaps, a kind of system synergy.
All this “theoretical “ is nice but I have owned balanced gear in the past and sorry those advantages don’t manifest much in practice. The most important part, the sound, was also not better.
As to noise, my amp is dead quiet with 100db speakers...no need for power supply rejection when it is done right.
Any resemblance of class d to tubes is purely superficial...a remotely in depth listen reveals quickly otherwise.
Look here trust me they use it scroll down last pic.
I'd be more concerned about the coloration of the SET than the horns.
Distortion is one of the main reasons we hear differences in amplifiers. For example, the brightness and harshness of solid state is not due to a frequency response error; its caused by higher ordered harmonic distortion (although at what is often called a 'low level'). SETs OTOH tend to make a prominent 2nd order, which results in 'bloom' and 'warmth'. From these two examples we can see that the ear is far more sensitive to higher ordered harmonics; this is because it uses them to gauge sound pressure.
But there is more to it than just that! The presence of the 2nd or 3rd harmonic (both of which are treated by the ear in the same way) can mask the presence of the higher orders if that 2nd or 3rd is present in enough quantity. This is why tube amplifiers sound smoother than solid state, even though they have more higher ordered distortion.
So far this is all easily confirmed both by listening and measurements- they are in agreement.
Now a circuit that generates a 2nd order as its primary distortion component has what is known mathematically as a 'quadratic non-linearity'. If the circuit generates a 3rd as the primary distortion component it has what is called a 'cubic non-linearity'. If the former is present, as the order of the distortion is increased, it falls off at a slower rate than a circuit having the latter.
So we can see that if we can build a circuit with a cubic non-linearity (assuming that real linearity is out of reach) it will be less colored as it will have less distortion, not the least of which is the fact that the primary distortion will be at a lower level than seen if a quadratic non-linearity is the main influence.
So now the question is- how do you do that?? In simplistic terms, these two differences in distortion are seen in single-ended circuits as opposed to fully differential and balanced circuits.
If you mix the two types of circuits, as is common in traditional tube amplifiers like the Dynaco ST70 (single-ended input, push-pull output) you'll get both types of non-linearities. When this happens a more prominent 5th is present, and distortion drops off at a slower rate as the order of teh harmonic is increased.
So far I've kept the effects of negative feedback out of this conversation. But it has a dramatic effect on what we hear. But I think I'll leave that for later, as I only have so much time
Anyway, one advantage of SETs is that as power is decreased, distortion falls off to unmeasurable. This is all about that 'first watt' which has to be clean. SETs are pretty good about this. By comparison, large push-pull amps are not, since below a certain power level (usually around 5% or so), distortion starts to go back up. This is why SET users often talk about that 'magical inner detail'.
But if you have a fully differential circuit (and no feedback) you can also achieve this linearly decreasing distortion curve as power is decreased, with no rise in distortion at lower power levels. And of course you can build small push-pull amps if you want; these are rare in good quality and I would surmise never compared directly watt for watt to SETs.
SETs are traditionally power challenged as it is very difficult to build an output transformer that has bandwidth and power at the same time. This is why the 300b was King in the 1990s, why the 2A3 ascended the throne 20 years ago and why the type 45 power tube (good for about a watt) is now the object of admiration. But if you have a fully differential amplifier you can have the power and bandwidth at the same time, while using the same power triodes (if you want).
So IMO/IME there is no argument for SETs, other than someone simply not having heard something that is both sonically and measurably better.
Some argue that SETs are very dynamic and it is often true that they sound that way. But in reality, what is happening is the amp is being driven hard enough that the higher ordered harmonics are showing up as the distortion of the amp is increased (SETs are often 10% THD at full power), and where the power is needed is often transients. Since the ear uses these harmonics to sense sound pressure, and since they are showing up on transients, presto- you have an amp that sounds 'dynamic' but its really distortion masquerading as such. Simply by you're reading this, I may have ruined it for you because of how our brains process music. To avoid this phenom, the speaker should be efficient enough that this does not occur: hence horns.
A mark of any good system is the quality where it does not sound loud even when it is. That takes clean power which SETs cannot provide except at low power. This is often why SET owners will tell you that '90dB is plenty loud enough for me'. If the higher ordered harmonics were not present, it would be natural to turn the volume up higher.
Hi Atmasphere,
Brilliant stuff!
(And I believe you should post more, as every time I read your posts, not only do I learn a lot, but I also drool about having your amps drive big electrostats or proper high-efficiency speakers.
)I was wondering how the concepts here mesh with what I experience with SET / horn (and horn-type speakers like Zu): When playing SET amps with high-efficiency, the sound - in terms of clarity and detail, actually sounds like solid state, without the horrifical analytical sound artifacts SS brings to the table. On the other hand, hooking up push pull tube gear to big box speakers (Wilson, Magico, Sonus, etc.) , I am hearing a soft, warm, syrupy, colored sound....
So I find SET amps, actually sounding more transparent than both regular push - pull tube amps, even when possibly distorting on a 95 efficient or higher speaker, and more musical than SS?
If you could please clarify potential causes, in terms of your post above, I would be grateful.
Thanks
Just to say that I had great sound with balanced equipment, Atmasphere included, and with single-ended equipment. Can't associate balanced or single-ended with "better", they are just different. It depends on our preference.
Although it is surely risky to generalize, balanced mode seems to carry more information concerning soundstage and dynamics, single ended seems more "comfortable" but less real. My opinions are firmed on listening with box speakers and electrostatics, nothing else.
Fortunately professionals use balanced lines, otherwise probably our recordings would have a lot less information.
BTW, some units having both single-ended and balanced inputs have compromised balanced lines - just add-ons for convenience.Similar threads
