Considering A 20-40 Watt Stereo SET Amp

The Willsenton R800i looks like a sonic bargain at it's price point.  Thanks for the tip.

@jbhiller

At $3k, I highly recommend the Willsenton R800i. It’s 45w SET. To get this power it has a massive transformer and weighs a ton. It has 3 inputs, remote, VU meters —not to mention it sounds lovely and robust.

This is an excellent suggestion. I can’t think of a better/ comparable option at this price point. Genuine 805 robust 45-50 watts pure SET toplogy. If one really desires a SET sonic experience, the well meaning solid state recommendations aren’t the same (Although fine in their own right). Get the genuine item.

Charles

Thanks @jjss49 !

 

I should note that the Willsenton is a Chinese made amp. It is reportedly made in the same factory as line magnetic. The product is very similar. They also reportedly have service centers here that can work on it, but I have not had the need.

it’s a wonderful amp. It has an interesting and effective tube compliment. 805 power tubes fed by 300b, 6sn7. While I haven’t tested it with lots of loudspeakers, it is very powerful. It is well made and 100lbs. I like the aesthetic more than Primaluna, which I also owned.

As summer approaches, I’ll move it out for Class D. At that time I will open it up, bleed out any current in the caps, and assess the internal quality.

The midrange on this amp is spooky clear and insightful.

Downsides are only: unknown, if not questionable, support and service, and weight. It is 100lbs.

I also am of the opinion that this is a statement amp and that the company is not likely making strong margins Sure that lets buyers get something amazing at a low price, but that’s not a good long term business model and can actually hurt the customers. You can email support and they respond in a day—yet it’s a far cry from say Audio Research support and service.
 

 

 

@jbhiller 

good to see your handle back here posting

hope you are well!

@stereo5 

At $3k, I highly recommend the Willsenton R800i. It’s 45w SET.  To get this power it has a massive transformer and weighs a ton. It has 3 inputs, remote, VU meters —not to mention it sounds lovely and robust. 

The mono blocks sound like a good idea. 

Can be paired with a tube pre with variable outs for subs. 

Although it might sound schiity....

https://www.schiit.com/products/freya-n

You may want to check out Audio Mirror’s 45w SET monoblocks. Not a conventional SET, as it uses a pair of 6C33Cs wired in parallel, but has lots of power. I think there was a review in The Abscolute Sound. Hope this helps.

Consider a Firstwatt amp by Nelson Pass. The mosfet's he uses are kinda like little solid tubes. I built his F5 design and find it very tubey sounding.

How about forgoing the tubes and get a true Class A SE solid state integrated like this Sugen A21SE. It has all the features that you are looking for!

http://goldprintaudio.com/

https://www.sugdenaudio.com/a21se-integrated-amplifier

I use ASL Ki22 Fox integrated amp. I compared it to other integrated or separate amps but the ASL is still with me after many years. 22W/channel, 6C33C power tubes, 6SN7s - both are still available as military spec or NOS for tube rolling. I recapped it a while ago. No problem. It requires frequent bias adjustments, but that's the price for simplicity.

+2 on the Quicksilver Audio!

Mike

Check out Quicksilver Audio. I own 300B amps, and Quicksilver Audio amps also. Quicksilver amps are biased partially triode mode, and are the closest conventional tube amps I have heard that sound like SET. They have a new integrated amp, using 6BQ5/EL84 tubes. 6 inputs. $2495. I have owned several of their tube amps, and have always enjoyed their sound. Currently have the Mid Monos. 

Link here:

Integrated Amplifier – Quicksilver Audio

SET 845s are musical but also a little slow and rolled off sounding (from the ones I have tried or owned). 

I have a 300B / 845 amp that I would love to get rid of but no one has a forklift to pick it up!

To the OP for SET in that wattage the 300B quartet in parallel single ended mode gets there. SET KT150s tend to sound more hifi / solid state but can produce the wattage. Closer to the KT88 push-pull tone.

Not sure about a SET with pre out for sub though. Icon Audio has a tape monitor circuit but not variable out pre.

https://iconaudio.com/stereo-300-mkii-300b-integrated-amplifier-stereo-300-mkii

https://iconaudio.com/stereo-30-se-single-ended-integrated-amplifier-stereo-30se

https://en.cayin.cn/features/8/57/73/369.html

 

The SET’s with 845’s are very musical and run around 4-5 K.....I have one with 22 WPC...or try CAYIN , who always get great reviews. (Thomas and Stereo)

I believe that Canary Audio makes both zero NFB SET and push-pull 300b amplifiers. I don’t know if anyone has done a direct comparison between these two versions.

@charles1dad I have to imagine Canary has... PP amps, just like SETs, vary quite a lot depending on design concerns! For example, single-ended circuits exhibit in mathematical terms a quadratic non-linearity, which describes how the harmonic distortion arises. When measured, it is found that the math accurately predicts the harmonic content.

OTOH, a fully balanced differential circuit exhibits a cubic non-linearity. In this case the even orders are cancelled; ideally only odd orders remain, but they fall off at a much faster rate as the order of the harmonic is increased (with the 3rd harmonic masking them). This again is accurately predicted by the math.

So this is where I'm going with this: when you combine both single-ended and PP circuits in the same amp (such as seen in almost any traditional PP amp, like a Dyna ST70), you get both non-linearities. This tends to exacerbate the 5th harmonic (Norman Crowhurst also wrote about this problem).

So if the comparison is between an SET and and a traditional PP amp, you are getting more 5th than you would if the PP amp was fully balanced. I've no doubt this is a lot of why SETs can be preferred.

These are all readily solved engineering issues though- its not hard to build a PP amp that does not have that problem! This is part of what I meant when I used the phrase 'cast a wider net'.

I have multiple systems. But I pretty much have had a SET-based system since the late 1990s. Owned many many SET and speakers that can run on them. With SET the lower power models are mostly the best sounding. But you have to carefully select loudspeakers and today not many truly SET-friendly designs exist in the market. I joke with others about SETing one’s system up for failure and when I see SET amps it’s mostly not on a SET-friendly loudspeaker. I design my own loudspeakers for SET use and have done so for nearly 30 years. SETs are amazing but all your ducks need to be in order to hear this and once done you don’t have any real limits on music types played and SPL. A common complaint from those who SET their systems up to fail.

there are many many out there, new and old, i cannot say i have kept up with the newer options but in my past travels i have really enjoyed dennis had's cary 300b series ... in particular i still have an original 300b sei... with lovely 6sn7 input and driver tubes -- really lovely sound with speakers that are efficient enough

good luck on your search

to put what @atmasphere has so eloquently stated into a nutshell - it‘s all in the implementation…

I like the el84 tube and it is often used in pretty nice sounding low-cost amps.  It is an indirectly heated pentode tube, but, the tube type does not determine anything particular about its sound.

While my suggestion isn't exactly what you are looking for it may be worth looking into an el84 based amp. They're not SE but they are triode. My fisher has much of what you want. Maybe try the quicksilver integrated. It is more modern than my 60+ year old gear.

I own a parallel SET and two pushpull amps.  My favorite is a flea-powered pushpull that runs the 349 output tube.  The best tube amp I've heard is a custom-built output transformerless amp followed by a pushpull amp running the extremely rare 252 tube.  In other words, I don't have favorites that are consistently one topology.  

I think the OP should broaden his search to all types of tube amps, not just SET amps, particularly because higher powered SET amps are quite pricey and none have sounded as good to me as the low-powered SET amps, which might work if high volume levels are not a priority, but, are probably not ideal given that the speakers are not near the 100 db/w efficiency level that is more suited to low-powered SET amps.

@atmasphere 

IIRC, your SET uses a 300b. You might find it interesting to hear a class A PP zero feedback amp using the 300b. In that way variables are eliminated, all of which affect the distortion and therefore the 'sound'.

Yes my SET does. I believe that Canary Audio makes both zero NFB SET and push-pull 300b amplifiers. I don’t know if anyone has done a direct comparison between these two versions.

 Charles 

I have owned two terrific push pull tube amplifiers, 100 watt KT 88/6550 and 40 watt el34. I have 300b SET mono blocks 8 watts. All three work very well with my 94 db sensitivity/14 ohms speakers. The SET is the most nuanced, open, transparent and in addition the most emotionally involving, 3-dimensional and tactile of the three amplifiers. Simply more real and believable presentation. That’s my listening experience. For other listeners if can certainly be different.

@charles1dad 

I don't doubt your experience.

Those larger amps you mentioned use feedback. A long time ago I read a passage by Norman Crowhurst (an early tube guru), discussing what happens when feedback is applied in an amplifier. He described the spot that occurs as the 'feedback node'; the cathode of the input tube. The thing is, that tube, no matter how good, isn't linear. So when the feedback is mixed with the incoming signal, its a distorted by the tube, so causes additional distortion as a result. Crowhurst described that as 'higher ordered harmonics, inharmonic distortions and intermodulations'. All of these are unpleasant to the ear and readily audible (usually has harshness and brightness at some level).  Those things did not go away simply because the amplifier is a bit newer...

A simple remedy is to not mix the feedback inside a tube. It can be done using a resistor divider network entirely outside the amplifier. It helps a lot if the amplifier is also reasonably linear without feedback! This practice is exceedingly rare in high end audio.

Most pentode and tetrode power amps I've seen really need that feedback to work. But if the amp was already musical without it?? That's pretty rare... I'm not contesting your experience. What I'm saying is to find out how this works, a wider net has to be cast.

I started studying SETs in the early 1990s (with early editions of Sound Practices magazine as the influence). I've heard some SETs that seemed quite nice, but so far none surpassed some (but certainly not all) of the PP amps I've played. 

IIRC, your SET uses a 300b. You might find it interesting to hear a class A PP zero feedback amp using the 300b. In that way variables are eliminated, all of which affect the distortion and therefore the 'sound'.

 

@stereo5 You're very welcome man, and I wish you the best of luck!

 

 

@atmasphere 

SET guys won't like this of course, but I challenge any one of them to a simple set of questions: When did you compare to a PP amp of the same power? Barring that, did you compare to a PP amp using the same power tubes and construction technique (and parts)? I've done both

I suppose am a “SET guy”.  I’m not the least bit bothered by this and I haven’t done the above stated challenge. In my audio journey, if I’ve learned anything it’s choose what type of sound and music presentation that makes you most happy and connected.

I have owned two terrific push pull tube amplifiers, 100 watt KT 88/6550 and 40 watt el34. I have 300b SET mono blocks 8 watts. All three work very well with my 94 db sensitivity/14 ohms speakers. The SET is the most nuanced, open, transparent and in addition the most emotionally involving, 3-dimensional and tactile of the three amplifiers. Simply more real and believable presentation. That’s my listening experience. For other listeners if can certainly be different.

@stereo5 I strongly encourage you when the time is right to obtain suitable speakers and try a good quality SET. See what you think. Maybe even do the amplifier challenge mentioned above.  It may or may not be for you.  I can only report that it works extraordinary well for my desires.

Charles
 

@stereo5 What you are up against is that its really hard and really expensive to make power with SETs. By really hard, one of the aspects of that is bandwidth goes down the more power you need (due to output transformer limitations). That is why the smallest SETs have the reputation for sounding 'the best'. By the time you get over about 7-8 Watts (300b territory) you have trouble getting the amp to have what might be considered 'hifi' frequency response.

When people compare SETs to PP amps, its usually an apples and oranges thing! That is because the SET has no-where near the power of the PP amp, and the PP amp doesn't have Directly Heated Triodes, like nearly all SETs do, and likely runs feedback and pentodes as well.

To put that PP amp on a level playing field with an SET, they should have the same or similar output power at clipping. People don't do that- because there are almost no PP amps that only make 5 to 7 Watts! And no-one even considers putting a 30 Watt SET against a 30 Watt PP amp. It would get creamed. That's mostly because at that power level, the bandwidth limitation imposed by the output transformer is readily audible. And measurable as well... and the PP amp would have a much greater amount of usable power...

RE usable power: SETs rarely use feedback so their usable power is up to about 20% of their rated power. Above that power level, they take on a 'dynamic' quality as higher ordered harmonics show up on musical transients (where the power is needed). The ear uses the higher ordered harmonics to sense how loud a sound is, so when they are only on the transients, you get a 'dynamic' quality.

Dynamics should come from the signal, not the amp.

If you are not willing to replace your speakers, which are not efficient enough to really work right with most SETs, then look at a PP amplifier. There are triode PP amps that run class A with zero feedback, FWIW. IMO/IME they sound better than SETs too: more transparent (due to lower distortion), more authority (due to better bass power response) and overall more true to the signal- the music.

SET guys won't like this of course, but I challenge any one of them to a simple set of questions: When did you compare to a PP amp of the same power? Barring that, did you compare to a PP amp using the same power tubes and construction technique (and parts)? I've done both. I can go into in depth...

 

I have decided that it will be too costly to buy a SET integrated with all the features I need so I have decided not to go any further.  I am not willing to compromise on a push pull tube integrated (been there, done that) so I surrender.  Perhaps in the future if I decide on a pair of Klipsch Cornwall IV, I will rethink this again. 
 

I want to thank everyone who contributed to this thread and a special shout out to Aric Audio, thanks ever so much. 

@stereo5 Wrote:

 

Considering A 20-40 Watt Stereo SET Amp

Maybe 8 watts!

Look at the Coincident Dynamo 34SE MKIII integrated amplifier. Price: $1799 US

See below:

Mike

https://www.coincidentspeaker.com/mpsip_amps.html

 

as @three_easy_payments has identified, your speakers are the determining factor here. You are really going to have to audition a range of tube amps before purchase as the results of the complex speaker- amp output stage interaction can not be predicted accurately from specifications and will tend to dominate sonic outcomes.

Conventional wisdom would dictate that those amps with a 4 ohm tap would be more successful. However, this may not be the case and each amp should be auditioned on its own merits.

I would therefore caution strongly against falling into the trap of auditioning a single recommended amp and buying it because it sounds nice (most tube amps sound nice), and instead make a point of auditioning a range of different tube amps before you take the plunge on your favourite.

I would also have a really good SS power amp on hand as a baseline reality check as to the overall viability of tubes with your speakers.

@three_easy_payments ,

I totally agree with you.  This kind of takes the wind out of my sail.  I wish I could hear a Prima Luna before I take the plunge.  I will look online to see if there are any dealers even remotely close to me.

I don't think your 4 ohm 90dB speakers will really allow a SET amp to shine.  

I used my Had Firebottle SEP with 90db or so speakers and it worked fine...you could test the distortion by cranking it but meh...it's a wonderful amp. 10 to 17 watts pc allegedly depending on tubes used, and it will work with a lot of different tubes generally of the KT variety...

@bgchz ,
I need a stereo integrated and it’s 6K over my budget, but thank you.

Audio Mirror Reflection 45 monoblocks. Amazing!

I have been researching since last night and have come to the conclusion that to get something close to the power and features I want, I would be looking at close to 10 grand.  That is totally out of the question just to have a third amp in play.   So I need to rethink my situation.   I have been looking at the Prima Luna Evo 4000 and it seems to have everything I would want regarding power and features, but of course it isn’t a SET amp.  I have already owned and sold a Rogue Cronus Magnum integrated because I felt is was grainy sounding and just wasn’t something I truly liked.   I wonder how much better or worse the Prima Luna would be.    Tough decisions ahead.  

@speedthrills The customer's budget was observed when I replied, and I do custom work to fit budget and feature requirements. While what you stated would seem logical, it doesn't hurt to send an inquiry and find out for sure! Best regards, Aric

@arcticdeth,

I am already using a McIntosh MA6600 200wpc integrated.  I use less than 2 watts on peaks. 

Line Magnetic 805 SET will have enough power to drrve your speaker.

Even with just 45 Watts spec, it had better control of bass than 100 watts ogue Cronunus Magnum II.

I had been using earlier version 508 for five years.

Thomas

250 W rms strereo amp. MIN
sure it will play softly, if you want@,little juice, 40W will clip. Don’t have the headroom for full on orchestra, rock music,  blues.

May sound ok, get some sack, then your all set when-speaker upgrade time comes

 

check the Gon every couple days, something will pop up

 

 

low volume mostly,..

 

 

 

your,golden,with a 40W amp  

those speakers need some current to sound best!

just sayin

 

The JAS Array is a 45w SET that can be ran as an integrated with 4 inputs and a passive preamp section or, with the flick of a switch, can be ran as a stereo amplifier using your choice of separate preamps.  With premium tubes, it's one of the best amps I've had.  That being said, those tubes will cost you a fair amount and it does put out a huge amount of heat.  It's also enormous and very heavy.  I sold mine to simplify and now have an itty bitty Class D amp.  The JAS sounded better but the Red Dragon S500 is much easier to live with.   Check out the 6 Moons Review of the JAS Array 2.1.  

As others have said, the SET option at your power and price requirements doesn't exist (Aric will come in much higher in price by the time they create a customized integrated for you more than likely), why not a Prima Luna and call it a day? 

If you want to seriously check out SET amps… consider a SET headphone amp. You do not need the power you need for your speakers. You can check out the sound and decide if this is the direction you want to go. There are other ways of getting more power and midrange bloom in a main system if you decide this is the way you want to go.

 

Typically you can put together an equivalent system at 1/10th the cost on a headphone system to test the concept. I assembled an incredible 300B headphone system for $15K while my equivalent sounding main system cost about $150K.

@stereo5 You're welcome, and thank you as well. Yes, as I had mentioned above the Super KT88/120 can be outfitted with additional inputs and a volume control and when used with 6SL7 Input tubes, can be driven to full output directly from a source. I can add a set of RCA line level outputs as well to allow driving a powered subwoofer. I'm not sure if you need remote capability for volume as well? If you'd like, please contact me using the Contact Us (through my website) and let me know what options/features you may like and I can try my best to help. 

 

Best regards Aric

@aricaudio,

Thank you for your response but I need an integrated amp. I’m looking for something with 3 line level inputs and a one pre output for my subwoofer.  Do you have something similar?

True SETs (single-ended triode) amps cannot do 20-40 watts unless they’re big transmitter tubes such as the 211 or 845 and they use over 1,100 volts. An SEP (single ended pentode), running in ultra-linear or triode mode can get 20 watts per channel however. A good example is at the link below and can be driven directly from a DAC, CDP, etc. Volume control can be added as can additional inputs for right around your budget:

https://aricaudio.com/products.php?product=SPRKT88120

Prices are not higher for what you get, considering prices for an Audio Note 211 amplifier start at $20k, Air Tight's 211 is $10K, Thomas Mayer's is $27K, and my Super 211 SET is $11,800- so comparable in price. Since a 300B is incapable of 20-40 watts, and 2A3 has even less power, 45 half that, this basically leaves pentode/tetrode single-ended amplifiers for the kind of power you’re looking for unless you go push-pull.

 

 

Best regards, Aric

I had already checked out Aric.  Unfortunately, he doesn’t have any SET integrateds over 10wpc and his prices are much higher than I am willing to spend.  Thanks for responding.  

Check out Aric Audio.   Made here in Mass , I am pretty sure he has something in his product line that would appeal to you