[Tyson]

  This can be a simple thing. Get both with a money back guarantee and then listen to both. Opinions are just that. Use your own ears to decide PERIOD .

charles

Listen to this man.

[ketcham]

I have the only consumer built Daedalus Zeus at 99 dB.  I have a very large room.  23' cubed plus another 15' behind and 20' to the right.  Open design timber frame home.  The PX25 is 7.5W rated. 

[FullRangeMan]

Thanks Ketcham these data make sense.

[sunnydaze]

  This can be a simple thing. Get both with a money back guarantee and then listen to both. Opinions are just that. Use your own ears to decide PERIOD .

charles

Or take a chance and buy used at a price such that you breakeven (or near) if you need to resell.

I've been doing this for 25 yrs and have stumbled upon some gems -- after research and due diligence, of course.  As has been already stated many times, you just gotta try it for yourself.  This is just another way to do so.

For a specific rec, I can confidently point to the Almarro 318B.
My local buddy has one on his ZU DW's and it is fantastic.  One of the more robust SET amps that on the Zu's provides that SET magic with punch and a well defined / detailed bass.  And you will never worry about it running outta gas with the DW.

I've seen it used as cheap as $1200.  More common in the $1400 - $1500 range.

Here's one with some really nice upgrades that sold a few years ago for approx $1500,  IIRC.

https://www.audiocircle.com/index.php?topic=145129.msg1552406#msg1552406

Good luck with your decision.

[ketcham]

The format is off here....  But attached is the link.

Basically if your published sensitivity is true, sensitivity gives exact dB at 1 watt, for each doubling of wattage adds 3 dB. 

A 99 dB speaker will give 105 dB at 4 Watts and 108 dB at 8 Watts. 

http://www.colomar.com/Shavano/spl.html


Interpreting Speaker dB Ratings
Speaker SPL in dB     86     87     88     89     90     91     92     93     94     95     96     97     98     99   100   101   102   103   104
Actual SPL (Sound Pressure Levels)
1 Watt
                                 86     87     88     89     90     91     92     93     94     95     96     97     98     99   100   101   102   103   104
2 Watts
                                 89     90     91     92     93     94     95     96     97     98     99   100   101   102   103   104   105   106   107
4 Watts
                                 92     93     94     95     96     97     98     99   100   101   102   103   104   105   106   107   108   109   110
8 Watts
                                 95     96     97     98     99   100   101   102   103   104   105   106   107   108   109   110   111   112   113
16 Watts
                                 98     99   100   101   102   103   104   105   106   107   108   109   110   111   112   113   114   115   116
32 Watts
                                101   102   103   104   105   106   107   108   109   110   111   112   113   114   115   116   117   118   119
64 Watts
                                104   105   106   107   108   109   110   111   112   113   114   115   116   117   118   119   120   121   122
128 Watts
                                107   108   109   110   111   112   113   114   115   116   117   118   119   120   121   122   123   124   125
256 Watts
                               110   111   112   113   114   115   116   117   118   119   120   121   122   123   124   125   126   127   128
512 Watts
                                113   114   115   116   117   118   119   120   121   122   123   124   125   126   127   128   129   130   131
1024 Watts
                                116   117   118   119   120   121   122   123   124   125   126   127   128   129   130   131   132   133   134
2048 Watts
                                119   120   121   122   123   124   125   126   127   128   129   130   131   132   133   134   135   136   137
Some Color has been added to show what it takes to get 100 dB, 110 dB, 120 dB and 130 dB SPL.

Higher SPL = Louder

How does this relate to what you hear?

40 dB SPL - Very quiet living room.
60 dB SPL - Average Conversation 5 feet from person speaking.
80 dB SPL - Same person shouting.
90-100 dB SPL - Platform of subway station as train arrives.
130-150 dB SPL - 100 feet behind airplane jet engine.

[sunnydaze]

As I'm sure we all know, it's not just about volume.  It's about driver control, transient attack / dynamic swings, and ease.

For example:
My speakers are 90 db and a relatively flat load.  I've lived with them for over 10 years and I don't find them particularly hard to drive.  They sound glorious run full range with a quality 50 to 100wpc amp.  I typically listen at about 75 to 80 db.  When I use my 20 wpc P/P tube amp it gets more than plenty loud enough, and your chart says it will reach over 100db, but it just doesn't sound "right".  Sound is sluggish, distant, a bit veiled, lacks transient attack and dynamics, and the bass is soft and tubby.  Why?  Because the amp cannot properly control the 10" woofer.  Simple as that.

As further proof of this bottleneck, when I passive biamp and use this same amp on top part of speaker only (plus a more powerful amp on the bottom, either tubed or SS) the sound is real good. 

So when run full range, despite the fact that this amp's 20wpc can crack my eardrums, it simply doesn't produce the "right" overall sound due to it's inability to "control" the drivers properly.

[ketcham]

YES!  Absolutely agree and well stated. 

This has been my dilemma.  I did not notice any deficit when I compared my parallel 300b SET to single tube circuit amps, EXCEPT on one bass heavy track that to me just did not sound right.  I think the amps cover 95% of my listening.  This doubt made me order a new custom push pull Allnic amp - M2500 push pull for 20W PX25 tubes.  (300b 30W or KT150 100W continuous standard).  These amps are unique because it uses a tube rectifier in place of solid state circuit design (conversion to DC power).  I am hoping the best of both worlds.  Objective and clean with tight bass seen in push pull design while retaining the musical qualities seen in SET amps.  The amps are a new design and not seen in US to date.

It's an experiment and an investment.  I'm investing in custom amps because I like the character offered of the PX25 over the 300b.

My aural memory sucks.  I can not assess adequately unless I have the amps in the room together and ideally the same tube type and manufacturer.   

[JLM]

As I'm sure we all know, it's not just about volume.  It's about driver control, transient attack / dynamic swings, and ease.

For example:
My speakers are 90 db and a relatively flat load.  I've lived with them for over 10 years and I don't find them particularly hard to drive.  They sound glorious run full range with a quality 50 to 100wpc amp.  I typically listen at about 75 to 80 db.  When I use my 20 wpc P/P tube amp it gets more than plenty loud enough, and your chart says it will reach over 100db, but it just doesn't sound "right".  Sound is sluggish, distant, a bit veiled, lacks transient attack and dynamics, and the bass is soft and tubby.  Why?  Because the amp cannot properly control the 10" woofer.  Simple as that.

As further proof of this bottleneck, when I passive biamp and use this same amp on top part of speaker only (plus a more powerful amp on the bottom, either tubed or SS) the sound is real good. 

So when run full range, despite the fact that this amp's 20wpc can crack my eardrums, it simply doesn't produce the "right" overall sound due to it's inability to "control" the drivers properly.

What you're describing is called "damping factor" and relates to amp control of the woofer.  Tubes typically have very low damping factors compared to solid state.  So bass from tube amps can sound "bloated" or "exaggerated" and bass from solid state can sound "constipated" or "lifelessly tight".  Matching of amp and speakers is the key.  So as others above have recommended, home audition is the answer.

[-Richard-]

Many years ago I heard a 45 tube amplifier and fell in love with what I thought was a uniquely musical and deeply involving presentation of music. Voices sounded ‘present’ and had a strangely human, dimensional quality. Instruments had textures that could be felt as well as heard. That magic stayed with me and yet over the years I experimented with several other types of speakers besides high efficiency, high sensitivity examples, necessitating purchasing higher watt, higher current amplifiers.

As I moved in and out of a few different speaker paradigms over the years, and owing to my very limited budget, I had to sell two different 45 tube amplifiers in order to pay for amplifiers the lower efficiency, lower sensitivity speakers needed.

Now I am using the Yamamoto A08S 45 tube amplifier to drive the high efficiency, high sensitivity Lowther PM5Alnico speakers that handle the frequencies from the lower midrange up, in my open baffle speakers. The lower midrange down is handled by a 15” driver with its own digital integrated amplifier. The Lowther's are around 98 db sensitive depending on who is measuring them (the British come up with a lower number than did their former American importer).

Because I stream Tidal through Audirvana’s interface software, I have access to Audirvana’s volume control, which allows me to substantially increase the volume. Although I would like to use Audirvana’s volume control on maximum, I have read this preserves everything available musically within the streaming file, most of the time I cannot. My preamplifier for the A08S, which is really a voltage regulator being a ‘passive’ design, sometimes must be dialed down to the lowest setting so as not play too loud.

Considerations such as ‘headroom’ on my perhaps slightly more than two watt Yammie are irrelevant using Audirvana’s interface. So is the need for an ‘active’ preamplifier, I am getting all of the dynamic impulse the music needs to come fully alive, harmonically and texturally, including what the British like to call ‘jump factor’ or what some American reviewers like to call ‘leading edge transients.

I am mentioning all of this to suggest that there are a few variable factors that can allow a 2 watt SET amplifier to play effectively if you are using a streaming service or CD player as your source; The CD player can be enhanced to deliver a signal with more than 2 volts output, an interface software like Audirvana with its specially designed algorythms that has its own built-in volume control, an active preamplifier or preamplifier that can deliver a strong signal, or perhaps a step-up device like the ones used for vinyl playback.

The question of whether an SET low watt tube amplifier has unique advantages over an originally designed j-fet or more exotic transistor, used in Nelson Pass’s First Watt amplifiers always dangles before us and of course as some of our sage community has already suggested, demands an in-home audition to be sure. In spite of my deep satisfaction with the Yammie SET I am still curious what a First Watt J2 sounds like as an alternative. Tube amplifiers do demand more work; you either have to spend a great deal of money on modern tubes, like I did for the EML 45 MeshPlates, or you must find NOS tubes that have a great deal of functional integrity. I have 4 sets of 45 tubes and each sounds a little different. One particular set is pure magic, but if or when they go it is not clear if I can actually replace them. It will cost more money and considerable time to locate another ‘magical’ pair, even if that is possible.

45 SET tube amplifiers if designed well and if they are reliable can deliver a very 'linear' presentation that does not overly emphasize a particular frequency and so can sound very close to ‘real’ music. However they do not all sound the same; they can be quite different from each other. Rather than feel stressed driven by a sense of urgency, which will will only led to your agonizing over which amplifier is perfect for your needs, why not allow yourself to take time. Yes, read everything you can, yes, audition in-home where a dealer is willing to work with you, but if you can, give yourself time. In time things will become clearer to you and you should be able to make your decision with confidence.

I am just pointing to a few more ways of thinking about all of this. Best of luck to you.

With Warmest Friendship  -Richard-

[FullRangeMan]

Good post Richard, I have seen First Watt have again a VFET amp:
http://www.firstwatt.com/prod.html
Its the SIT3 18W no feedback, unfortunately this production will be limited to 250 units only, not sure how much it cost though

[-Richard-]

Hi FullRangeMan ~ First Watt's offerings seem to be an attempt to bring a little of tubes 'magic' to transistors, let us say a more 'dimensional' presentation, and to accomplish this, Nelson Pass, whom I respect enormously, uses exotic or rare examples of transistors matched with his beautifully simple circuits. The whole question of what potentially constitutes 'magic' in terms of the contribution of an amplifier to the all-over sound of one's audio system is curious.

If we can agree that each major component to the audio chain contributes to what we are perceiving as the 'sound' of the reproduced musical presentation then where does one begin to make the kinds of decisions that will insure that we will be deeply satisfied with the outcome? If we begin with a speaker, for example, then every other component must address how to best allow the speaker to 'sing' at its best.

Once I began to work with DIY Open Baffle speaker designs I felt I could allow that to be the 'base-line' that I would build the rest of my modest audio system around, so the rest of my system fell into place around that decision. Next came what speakers I wanted to work with. Personally, I equate simplicity with elegance, aesthetically speaking. So, reflecting this approach, a single driver that could cover the entire frequency range would be ideal. But alas, that is almost impossible in the Open Baffle paradigm, the lower frequencies get cancelled by the back wave necessitating the use of a bass driver (many DIY designers use 2 bass drivers) and it is best if they have their own dedicated integrated-amplifier, which gives one better control with how the 2 drivers integrate for each musical piece. That led to my decision to re-enter the world of the 45 SET tube amplifier, I wanted the top-end to be as transparent and silky as possible. This in turn led me to consider using the highest sensitivity speaker I could reasonably afford. After a great deal of reading and some experimentation I decided on the Lowther PM5A for its high sensitivity. Since I purchased the A08S directly from Shigeki Yamamoto in Japan, I had him install a 15 ohm power transformer into the A08S to match the 16 ohm Lowthers. Shigeki winds his type C transformers himself.

I am not using perfect cables or interconnects, rather they are what I have accumulated over the years. My choice of DAC reflects my very narrow budget restraints, and since I wanted to experiment with MQA I choose the Explorer2. Incidentally, MQA is a hit and miss affair and not at all predictable.

And to go a little further into the idea of what potentially an amplifier can contribute to the all-over sound, I was more than a little perplexed by Srajan Ebaen's idea that the First Watt's SIT 1 needed an exotic tube preamplifier to sound its best, while at the same time suggesting that he no longer found 'magic' in SET tube gear. That is a strange business indeed. Srajan is simply 'designing' his own 'hybrid' amplifier in that case, and with tubes in the critical preamplifier stage! I mention this to suggest that we can not take 'reviews' too literally or even seriously without knowing the full story of what the reviewer values in the way of 'sound', including what each reviewers gear and tastes are built around. And we have not even addressed the important question of what music one listens to.

For myself, I seem to like to make decisions and then struggle to bring the things I have purchased to sound as good as I can on my limited budget. And I am still learning! Learning what I can do to bring magic to my home audio on my limited budget. It is good, I think, for anyone interested in putting together an audio system to keep in mind that audio in not an 'absolute'. There are many directions one can go to release the potential magic of music.

With Warmest Friendship -Richard-

[Tyson]

YES!  Absolutely agree and well stated. 

This has been my dilemma.  I did not notice any deficit when I compared my parallel 300b SET to single tube circuit amps, EXCEPT on one bass heavy track that to me just did not sound right.  I think the amps cover 95% of my listening.  This doubt made me order a new custom push pull Allnic amp - M2500 push pull for 20W PX25 tubes.  (300b 30W or KT150 100W continuous standard).  These amps are unique because it uses a tube rectifier in place of solid state circuit design (conversion to DC power).  I am hoping the best of both worlds.  Objective and clean with tight bass seen in push pull design while retaining the musical qualities seen in SET amps.  The amps are a new design and not seen in US to date.

It's an experiment and an investment.  I'm investing in custom amps because I like the character offered of the PX25 over the 300b.

My aural memory sucks.  I can not assess adequately unless I have the amps in the room together and ideally the same tube type and manufacturer.   

This is why I love my Super 7 speakers so much - flat impedance, high sensitivity mid/high drivers and percussive, super controlled self-powered bass section.  Cause tube amps do mids better and ss amps do bass better, IME.

[Freo-1]

Another recommendation to look at First Watt. 

[Wind Chaser]

Hello, I am desperate for advice.  I am looking for an amp for some Zu DWs that I recently purchased.  They are 97dB and 12 ohm.  I have a small room (16x11).  I listen to everything including large orchestral works and death metal.  I don't listen loudly, I am also not a bass freak, but I like to "feel" the music at times.  I have boiled down my choices to a Decware SE84UFO2 or a Coincident Dynamo with 300b tubes.  I am worried that I will run out of headroom with either of these amps, but especially with the Decware.  Can anyone offer any advice or experience?  Thank you.

I have once owned a Decware Zen SE 84C (not the UFO) and I have also more recently owned a Coincident Dynamo MK-II. I've also had ZU Druids about 10 years ago, but powered them with a Grant Fidelity 300b. I wouldn't worry about running out of power with either of these two amps, especially considering you don't listen loudly. If I had to choose between those two amps, I'd go for the Decware. I type much to slow to get into this via keyboarding, but if you'd like to chat via tele, shoot me a PM with your number, the time zone you are located in, an a few options as to what time to call.

John

[FullRangeMan]

I found the SIT3 price are in excess of $4000usd
there are great tube amps at half this price.

[sunnydaze]

This is why I love my Super 7 speakers so much - flat impedance, high sensitivity mid/high drivers and percussive, super controlled self-powered bass section.  Cause tube amps do mids better and ss amps do bass better, IME.

My Vaughn Triodes have a similar design approach:  upper part of speaker (mids and highs) is 97 db efficient - great for small tubes - and the bottom 12" woofers are self-powered with a gutsy digital amp.  Wavelength 300B amps are often used at the shows.

[2Bornot2b]

I am running Cornwalls (98 dB) with a pair of transcendent Sound SEOTL strapped to mono. They are rated fro 4 watts each. I have a small listening room and very seldom get my preamp volume over 9 o’clock. Then newer versions are 4 watts per channel if I recall correctly. Good luck.

[A_shah]

YES!  Absolutely agree and well stated. 

This has been my dilemma.  I did not notice any deficit when I compared my parallel 300b SET to single tube circuit amps, EXCEPT on one bass heavy track that to me just did not sound right.  I think the amps cover 95% of my listening.  This doubt made me order a new custom push pull Allnic amp - M2500 push pull for 20W PX25 tubes.  (300b 30W or KT150 100W continuous standard).  These amps are unique because it uses a tube rectifier in place of solid state circuit design (conversion to DC power).  I am hoping the best of both worlds.  Objective and clean with tight bass seen in push pull design while retaining the musical qualities seen in SET amps.  The amps are a new design and not seen in US to date.

It's an experiment and an investment.  I'm investing in custom amps because I like the character offered of the PX25 over the 300b.

My aural memory sucks.  I can not assess adequately unless I have the amps in the room together and ideally the same tube type and manufacturer.

John
PM me on verdict so far on the M2500 M311 PX25
Asghar

[OzarkTom]

I have this integrated arriving today. For most, probably just a desktop amp. My speakers are around 95db+ efficiency, so the 12 watts into 4 ohms should not be a problem for my taste. A class D amp with tubes in the preamp section. For $105 and free shipping, I will try one.

https://www.parts-express.com/dayton-audio-hta20bt-hybrid-stereo-tube-amplifier-with-bluetooth-42-usb-aux-inputs-headpho--300-3840