What’s the world’s best 2 watt amplifier?

VinylSavor · Nov 8, 2022

As I wrote: In a well designed amplifier the rectifier makes very little difference. So if a customer wants these to be used I use them. Since i always use them in a bridge together with TV dampers I still have the slow ramp up of voltage. The higher voltage drop can be compensated by higher voltage from the power transformer

Thomas

rooze · Nov 9, 2022

The Art Audio Carissa made wonderful noises playing through Klipschorns. I found the 845 tube to be the best match for Khorns, better than 300b, and various pentode/pp tubes. Of course it’s more powerful than the OP is looking for, but it does sound great if you can get your hands on one.

godofwealth · Nov 9, 2022

VinylSavor said:
As I wrote: In a well designed amplifier the rectifier makes very little difference. So if a customer wants these to be used I use them. Since i always use them in a bridge together with TV dampers I still have the slow ramp up of voltage. The higher voltage drop can be compensated by higher voltage from the power transformer

Thomas

Interesting. I think that is not what I’ve generally read from quite a few reviews on this forum or the web, where rectifiers were observed to have made a significant difference. When you say voltage difference, do you mean the reverse drop (my Amplitrex tester often measures around 25-30 V drop for a 415 V forward voltage)?

VinylSavor · Nov 10, 2022

Hi!

Yes I know this is contrary to what many believe. I design my components such that they are not changing their sound significantly when rectifiers are changed. In fact my amps do not need any accessory like special stands, cables or power conditioners to show what they are capable of.

It seems that some modern tube equipment is designed such that it encourages tube rolling and constant fiddling with it.

It is called forward voltage drop and it is the voltage drop within the rectifier
from plate to cathode. This drop depends on the current drawn. For a 5U4 that is typically around 40-50V, less if not much current is drawn. And this voltage drop varies between tubes, so the amp circuit gets different supply voltages. So if an amp reacts significantly to a change of rectifiers it would be worthwhile to understand why and if the difference in supply voltage is the cause.

Best regards

Thomas

Blue58 · Nov 10, 2022

As an example, my Loftin-White inspired amps sound different when swapping rectifiers not due to the rectifier itself, though I admit there is probably sound quality differences between them, but due to the changing parameters within the amp.

If the voltage out of a rectifier is less or more than the previous sample then all the voltages and current throughout the amp are affected. The operating points of the driver and output tube are changed, sometimes a little, sometimes a lot.

The same thing happens when the mains voltage is altered from say 242v to 231v.

So simply swapping rectifiers and then equating the sound quality change purely to the rectifier is false. It’s more correct to say that the sound quality difference is due to both the rectifier and to the change in operating point of the following circuit. As to how to apportion a percentage to either is more difficult.

However, the end result is what’s important. Roll those tubes to find your happy place.

Blue58

VinylSavor · Nov 10, 2022

@Blue58 . Exactly. And I see a recent trend to swap even different rectifier types, despite them having different parameters and max ratings. Some swap between 274B and GZ34, one is directly heated and the later indirectly heated. Indirectly heated rectifiers have much less voltage loss than the others. The resulting changes in sound should not be attributed to the rectifier.

You are spot on with the changes in op points. I have seen many circuits with marginal driver tubes which are not operated in the most linear region. Small changes of supply voltage will alter the sound. In such cases swapping different driver tubes will also change the sound.

It is preferable to have an amp with op points chosen such that the supply voltage can vary over a wide range without significant change. I have written about that many years ago on my blog:

The search for that 'magical' operating point

Hi! One of the most often asked questions about tube amps I get is: 'Which operating point do you recommend for tube xyz?' There is also a...

vinylsavor.blogspot.com

And a bit related to this a post about gain headroom and power:

Gain, Headroom and Power

Hi! Thanks to all who participated in the poll so far! There seems to be a clear trend for a SE amplifier concept on a budget, followed by...

vinylsavor.blogspot.com

Best regards

Thomas

beaur · Nov 10, 2022

godofwealth said:
I’ve recently started exploring the fascinating world of extreme low power amplifiers, think under 2-3 watts. No megabuck amplifier that requires a forklift to move (I once owned one of those behemoths, a Krell 750 MCx!). Since my current reference speaker is a pair of Klipsch La Scalas, 200 pound behemoths that look the size of a midsized refrigerator but are 105+ dB efficient, I’ve discovered I can get by with flea sized amplifiers. My current reference is a Triode Labs 45M monoblock SET amplifier. It uses 1 45 tube per channel to produce 2 glorious class A watts per channel. It simply sounds magnificent on my La Scalas. Here’s a pic of them. I’m using Sophia Electric Princess 274B rectifiers with NOS RCA 45s.

Are there better extremely low watt amps I should consider? Does anyone make a 2 watt class A solid state amplifier? Yes, I know Nelson Pass here in California makes his First Watt line. I don’t want 15-20 watts. I want just ONE glorious watt! Extremely high quality but extremely low power. The best components money can buy, but no unnecessary power. Suggestion?

View attachment 99960

There are several candidates out there not mentioned so far.

Amps based on the 50 would fit the bill. EMIA makes one and there are several other small builders that do custom work. I’ve had 50 amps for the last decade and love them.

Audio Antiquary (Mishima Mirnov) can make his amps in a variety of configurations to suit your tastes.

OMA make the Parallax (I work with them) that I also own and enjoy.

Arcturus also has an 801 that would fit the bill.

if you want to get really nuts Silbatone used to make an amp based on the Bendix 6900 that would send out 0.85W!!

there are others out there that my sleepy brain isn’t remembering now.

Beau

Salectric · Nov 10, 2022

Custom builders tend to dominate the 2 watt world. I would nominate my own 46 SE amps as candidates in any contest for best sound quality. They are simple 2-stage monoblocks with very few parts—-417a with an Interstage transformer coupled to the 46 output tube—-but each part was carefully selected in listening tests. Silver output transformers; Intact Audio Interstage; BlackGate WKZ caps in the power supply; Audio Note silver tantalum resistors, etc. With a simple design each part has an important role in the overall sound and one can take the time to choose the best sounding part for each spot.

To avoid any misunderstanding, my amps are not for sale. I just like to build my own gear.

charles1dad · Nov 10, 2022

@VinylSavor
Thanks for the links to your articles. “Gain, Headroom and Power “ is especially informative and enlightening.

If done right and proper SET amplifiers can sound unlike any other alternative topology. Your articles provide the insight and explanation as to why this is so.
Charles

charles1dad · Nov 10, 2022

Salectric said:
Custom builders tend to dominate the 2 watt world. I would nominate my own 46 SE amps as candidates in any contest for best sound quality. They are simple 2-stage monoblocks with very few parts—-417a with an Interstage transformer coupled to the 46 output tube—-but each part was carefully selected in listening tests. Silver output transformers; Intact Audio Interstage; BlackGate WKZ caps in the power supply; Audio Note silver tantalum resistors, etc. With a simple design each part has an important role in the overall sound and one can take the time to choose the best sounding part for each spot.

To avoid any misunderstanding, my amps are not for sale. I just like to build my own gear.

I have little doubt that your carefully and passionately built amplifier sounds sublime. Congratulations with this effort.
Charles

godofwealth · Nov 10, 2022

One interesting question seems to be choice of output tube. Popular choices are of course 300Bs, which can produce 6-8 watts, or 45s, which produce 2 watts. But I’m not familiar with some others being suggested. Is the 46 different from the 45? How about the 50 tube? Then there’s the question of availability. 300Bs are easily available from many vendors at different price points. 45s are much harder, although NOS supply seems plentiful. I’ve no idea who makes 46 tubes or 50 tubes.

bonzo75 · Nov 10, 2022

godofwealth said:
One interesting question seems to be choice of output tube. Popular choices are of course 300Bs, which can produce 6-8 watts, or 45s, which produce 2 watts. But I’m not familiar with some others being suggested. Is the 46 different from the 45? How about the 50 tube? Then there’s the question of availability. 300Bs are easily available from many vendors at different price points. 45s are much harder, although NOS supply seems plentiful. I’ve no idea who makes 46 tubes or 50 tubes.

46 is different and not expensive like 300bs. On Thomas’ blog you will find details of various tubes.

regarding 45 Vs 2a3 Vs 46 vs 801 Vs 50, you will just have to hear the amps, especially as they could be from different manufacturers, and tube rolls will make a difference . And you might enjoy all of them

low watt amp category is like any category, you can get lost in it trying to listen to various permutations and combinations. What happens to your 45 if transformers are swapped? Etc

godofwealth · Nov 10, 2022

bonzo75 said:
46 is different and not expensive like 300bs. On Thomas’ blog you will find details of various tubes.

regarding 45 Vs 2a3 Vs 46 vs 801 Vs 50, you will just have to hear the amps, especially as they could be from different manufacturers, and time rolls will make a difference . And you might enjoy all of them

low watt amp category is like any category, you can get lost in it trying to listen to various permutations and combinations. What happens to your 45 if transformers are swapped? Etc

Very intriguing, I found Thomas’ description of the 46 tube very fascinating.

Tube of the Month : The 46 (revisited)

Hi! As mentioned in the previous post about the recently built single ended amplifier , the 46 deserves more attention. So I selected it a...

vinylsavor.blogspot.com

It looks like there’s an ample NOS supply of these tubes. They are not “real triodes”, but not pentodes either. Healthy output as well. Sounds like they might be like push pull triodes?

charles1dad · Nov 11, 2022

@bonzo75
“low watt amp category is like any category, you can get lost in it trying to listen to various permutations and combinations. What happens to your 45 if transformers are swapped? Etc”

Agreed! Multiple permutations and variables. Sometimes an individual will declare that one specific low power DHT is superior to the all others.

This is nothing more (Or less) than opinion. Each and every tube has a signature and furthermore the amplifier implementation itself presents additional variables.

Anyone of these tubes could be brilliant as a choice but not one among them can be proclaimed the unequivocal best.
Charles

bonzo75 · Nov 11, 2022

charles1dad said:
@bonzo75
“low watt amp category is like any category, you can get lost in it trying to listen to various permutations and combinations. What happens to your 45 if transformers are swapped? Etc”

Agreed! Multiple permutations and variables. Sometimes an individual will declare that one specific low power DHT is superior to the all others.

This is nothing more (Or less) than opinion. Each and every tube has a signature and furthermore the amplifier implementation itself presents additional variables.

Anyone of these tubes could be brilliant as a choice but not one among them can be proclaimed the unequivocal best.
Charles

- There are certain tubes that are more linear than others when both are used in their right conditions.
- Some tubes allow for designing a simpler circuit than others, i.e. the lower watt ones compared to 845/211/833 so if speaker is fine with the low wattage you will get purer signal.
- Certain tubes in the same category, e.g. 300b are better than others
- And finally, you can just compare two amps in their optimized condition and see which one you prefer.
- It is quite clear if something relatively masks details or colors recordings, or rolls off frequencies. At least those can be avoided.

je2a3 · Nov 11, 2022

VinylSavor said:
Hi!

Yes I know this is contrary to what many believe. I design my components such that they are not changing their sound significantly when rectifiers are changed. In fact my amps do not need any accessory like special stands, cables or power conditioners to show what they are capable of.

It seems that some modern tube equipment is designed such that it encourages tube rolling and constant fiddling with it.

It is called forward voltage drop and it is the voltage drop within the rectifier
from plate to cathode. This drop depends on the current drawn. For a 5U4 that is typically around 40-50V, less if not much current is drawn. And this voltage drop varies between tubes, so the amp circuit gets different supply voltages. So if an amp reacts significantly to a change of rectifiers it would be worthwhile to understand why and if the difference in supply voltage is the cause.

Best regards

Thomas

I agree and very well said, Thomas. Thank you!

Ever since I started to DIY in the 90s, it has taught me that there is another world beyond the 300B, 2A3 and 45.

Amps I've built that produce less than 2 Wpc:

Western Electric 205D ~ 1.5Wpc

Type 10 triode ~ 1.5W

My simple 46 amp, ~ 1.3Wpc. I share a fondness for the Type 46 dual grid power tube with @Salectric even if our method of driving it is different. But therein lies the beauty of DIY, you only have yourself to satisfy.

Finally, my 750mWpc SE71A which I recently simplified to a 2-stage circuit.

beaur · Nov 11, 2022

charles1dad said:
@bonzo75
“low watt amp category is like any category, you can get lost in it trying to listen to various permutations and combinations. What happens to your 45 if transformers are swapped? Etc”

Agreed! Multiple permutations and variables. Sometimes an individual will declare that one specific low power DHT is superior to the all others.

This is nothing more (Or less) than opinion. Each and every tube has a signature and furthermore the amplifier implementation itself presents additional variables.

Anyone of these tubes could be brilliant as a choice but not one among them can be proclaimed the unequivocal best.
Charles

Charles,

My 50s are the best amps ever made, until I hear a great 45 system, then I hear a 46 and am smitten, then some weird tube I have never heard of...... Want them all.

Beau

beaur · Nov 11, 2022

je2a3 said:
I agree and very well said, Thomas. Thank you!

Ever since I started to DIY in the 90s, it has taught me that there is another world beyond the 300B, 2A3 and 45.

Amps I've built that produce less than 2 Wpc:

Western Electric 205D ~ 1.5Wpc

Type 10 triode ~ 1.5W

My simple 46 amp, ~ 1.3Wpc. I share a fondness for the Type 46 dual grid power tube with @Salectric even if our method of driving it is different. But therein lies the beauty of DIY, you only have yourself to satisfy.

Finally, my 750mWpc SE71A which I recently simplified to a 2-stage circuit.

I will take them all but I bet that 10 sound dreamy.

je2a3 · Nov 11, 2022

beaur said:
I will take them all but I bet that 10 sound dreamy.

Good choice! I'm listening to the SE10 (also simplified to 2-stage) as I type.

je2a3 · Nov 11, 2022

beaur said:
....Amps based on the 50 would fit the bill. EMIA makes one and there are several other small builders that do custom work. I’ve had 50 amps for the last decade and love them....

Beau

I remember dave S. being a proponent of the Type 50 triode even back in the 90s.

For a bit of nostalgia, here's dave (IA of EMIA) at the 1999 ny noise held at jc morrison's loft in Hoboken NJ. This might have been an early effort SE50 amp with a monster power supply.

What’s the world’s best 2 watt amplifier?

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