My Low Watt SET amp & High Sensitivity Speaker Journey ~

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-Richard-

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I have not written in our esteemed AudioCircle forums for quite some time. I had to give up writing in the Open Baffle Forum. It seems that low-watt high-efficiency speaker open-baffle designs are not as welcome there, as they used to be. Indeed, low watt amplifiers have been relegated to the rarest of niches as strange ornaments of times past by the audio community generally. There are exceptions of course, like Nelson Pass's highly praised First Watt, low watt offerings, and excruciatingly expensive Japanese low watt tube designs.

My interest in low watt amplifiers, like my Yamamoto A-O8S 45 Single Ended Triode, began I think, out of a perverse curiosity to find out why, when I was avidly reading about audio several years ago, so many older audio enthusiasts were so vocal that low watt amplifiers can potentially deliver magic to recorded music. The idea being that a simple circuit has less chance of messing things up. In the case of a Single Ended Triode design, letting the output tubes and transformers create their magic without unnecessary interference.

About 13 years ago I began living with 45 SET tube amplifier designs to drive my DIY open baffle speakers. I owned the Korneff and Modjesky versions and also heard in my home Garber's 2A3 SET amplifier. The Korneff could not drive my then wide-range speakers adequately. The Modjesky was designed to deliver 4 watts from the 45 tube, and was quite adequate but I was concerned that the 45 tubes were driven outside their optimally comfortable parameters. The Garber 2A3 sounded slightly soft if beguiling in other respects. Then I looked elsewhere for amplification. The idea of tubes began to feel like a burden, like when I used to collect classic American cars from the late 40's and early 50's.

But eventually I went back to my interest in the 45 SET amplifier. There was something about the sound that would not leave me alone. I purchased the A-08S 45 SET Yamamoto directly from Shigeki in Japan. His U.S. dealer had retired and as far as I know no one since then has come forward to be a dealer here for this marvelous and extremely original designer.

I remembered that the Korneff 45 SET amplifier did not have enough power to drive my previous choice of OB speakers, even though they were around 92 db sensitive. So I thought why not purchase the most sensitive wide-range speaker I could find that was not shockingly expensive. I first purchased the French 8" wide-range Supravox field coil speakers. I found fussing with field coils too much trouble for me and the sound was not optimal for what I was looking for, in spite of their being well received in some areas of the OB community.

Then I turned my attention to the Lowther PM5 Alnicos, that the then American dealer claimed was 97 to 98db sensitive, although the Lowther website gives them a lower rating. They are 16 ohm speakers, so I had Shigeki install 16 ohm output transformers in the A-O8S following Don Garber's personal recommendation. The Lowthers have since lost their US dealer, due to some conflict of interests, which is unfortunate. What drew me to the Lowther was their design first, then their sensitivity.

I was using NOS 45 tubes that I frankly loved for several years. Then this year I ordered EML Mesh Plate 45's from Jac in Germany. It was Jac who recommended the Mesh Plates over the Solid Plates for refinement and transparency.

Although I enjoyed what the Mesh Plates were doing for the music I felt that something was missing compared to my best pair of RCA NOS 45 tubes. Then about 2 months ago I re-discovered an old pair of Nordost flat speaker cables. I was a little concerned about their revealing nature, the Lowther's could spotlight the upper frequency region with components that lacked synergy with it. But after listening for a few days I was quite stunned realizing that the EML Mesh Plate 45 tubes had come fully alive.

So now I am hearing what I have been looking for since I began a 13 year journey into low watt, actually 2 watt, SET tube amplification and high sensitivity speakers. The music sounds alive, incredibly present, transparent, dynamic and realistic. Deborah and I are very happy with this set up. I am using the LightSpeed Attenuator, designed by George Stantscheff in Australia, as a passive preamplifier, so there is no preamplifier gain. What is entirely unexpected is that the A-O8S Yamamoto without any preamplifier gain plays surprising loud, and on rare occasions I do let the music rip for fun. My simple Open Baffle speakers, a slab of plywood with holes in it mounted on a plinth, helps to integrate the Lowthers with the room and create the illusion of space.

Now I would like to share a few simple tweaks with our Low Watt community. I am using Spotify which I pay $9 month for, which gives Deborah and I access to thousands of possible musical choices allowing us to explore music that we would never be able to find without extensive research. I am streaming the music through an iPad mini, which incidentally, I did not originally purchase for this use, so admittedly the DAC in the iPad Mini may not be optimal, which suggests that a great deal more refinement and resolution can potentially await us if I can find a low price DAC that works nicely with it. When in Spotify select the symbol icon on the top right side that looks like a flower-like button. A new page opens with a list of choices; select Musical Quality, then Extreme. That will allow access to 320 kbits resolution when it is available. Then select Playback; a new page opens, select Equalizer. A simple yet effective equalizer appears that lets you move white dots above a choice of 6 gamuts @ 60, 150, 400, 1k, 2.4k and 15khz. A green line connects them helping you to see how your 'chart' looks. There is a list below the eq chart, Accoustics, Bass Booster, Classical and several other selections that will show you what the Spotify engineers think works best with these musical styles, a handy reference to play with.

I realize that my choice of media is not optimal. These days if one reads Stereophile, they are pushing LP's which have proved extraordinarily resilient as media, and there are hundreds of dedicated DAC's and streaming components that promise high resolution; the newest format for digital streaming being MQA, which several streaming services now offer, including streaming components that are designed to unpack it.

But for now, what I am hearing with my 2 watt SET 45 amplifier and 97db sensitive wide-range speakers, using Spotify streamed through a simple iPad Mini can be quite thrilling.

Wishing Everyone Beautiful Musical Experiences and Everything Wonderful for the New Year. With Warmest Friendship ~ Richard
« Last Edit: 18 Dec 2017, 05:45 pm by -Richard- »

Bemopti123

Re: My Low Watt SET amp & High Sensitivity Speaker Journey ~
« Reply #1 on: 17 Dec 2017, 03:46 am »
Welcome back Richard.  It is most often that people such us here tend to mix passion for the technical aspect of musical reproduction rather than the performance, which should be supreme when it comes to audio.  It seems to me that you found the right balance between passion for equipment that delivers the performance that you most expect. Who cares about people who spend grandiose amounts of $$$$ in order to extract that last iota of sonical performance? I say as long as enjoyment is present and kicking, that should be the barometer of our audioquest. 

Even though I have invested $$$$ in equipment, as of late, I have gotten very little listening time from the setup.  Performance and convenience trumps technical prowess.  I say rock on with your system.   :thumb:

Wind Chaser

Re: My Low Watt SET amp & High Sensitivity Speaker Journey ~
« Reply #2 on: 17 Dec 2017, 10:32 am »
Hey Richard,

How's it going? You wouldn't believe changes I've made to my system since we spoke earlier this year. The Coincident was a great amp and it gave me many immensely pleasurable hours; but it's gone and I do not miss it! I've began a new journey and it already feels like I have arrived... :lol:  :D

I too am using an iPad with an Auralic Aries Mini to stream some amazing radio stations from around the globe, some in high def. Like you say it can be quite trilling. It all makes me wish I was 18 again. None of this stuff was available back then. This is a great time to be into this hobby.  :thumb:

roscoe65

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Re: My Low Watt SET amp & High Sensitivity Speaker Journey ~
« Reply #3 on: 17 Dec 2017, 03:00 pm »
Welcome back.  I am also toying with the design of high efficiency, open baffle speakers but am dealing with room constraints.  My amps and driver are different, but the principles remain the same.

As far as streaming choices, I use Tidal lossless streaming to a Chromecast Audio to my DAC via optical.  I have access to 46  million tracks at CD quality (albeit often remastered) for a discounted rate of $8/month.  I am on the verge of adding Roon, but as of the moment Tidal is the only streaming service that integrates with Roon, and there are recent rumors of Tidal running out of money.  If that happens I will shift over to Deezer until Spotify offers lossless, hopefully with Roon integration.

Streaming - even lossless - may not provide the same ultimate sound quality as vinyl or high resolution local files, but at this point in my life I do not wish to deal with hundred or thousands of pieces of physical media.  Streaming Tidal to my Schmitt Bimby, 421A amp and Omega speakers sounds at least as good as my similar system from over 20 years ago (California Audio Labs Delta/Alpha, Rankin Bugle direct coupled 45 SET, Cabasse 94dB 8” two-ways, Muse Model 18 subwoofer).

Jon L

Re: My Low Watt SET amp & High Sensitivity Speaker Journey ~
« Reply #4 on: 17 Dec 2017, 06:06 pm »
As far as streaming choices, I use Tidal lossless streaming to a Chromecast Audio to my DAC via optical. 

It's puzzling to me that in almost 2018, there is so few choices in solid, low-cost streamers that offer coax spdif output. 
Like most audiophiles, I already own high end DAC's and would like a good streamer that has good coax spdif out.  If no coax, would take regular toslink preferably over mini toslink, and analogue outputs are not needed. 

Looking around, I might just have to pick up Chromecast Audio unless there are better options.. :scratch:


FullRangeMan

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Re: My Low Watt SET amp & High Sensitivity Speaker Journey ~
« Reply #5 on: 17 Dec 2017, 06:10 pm »
Welcome back Richard :thumb:
I appreciated your advices when I was new here, thanks a lot.

belle harbor

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Re: My Low Watt SET amp & High Sensitivity Speaker Journey ~
« Reply #6 on: 17 Dec 2017, 09:18 pm »
I have not written in our esteemed AudioCircle forums for quite some time. I had to give up writing in the Open Baffle Forum. It seems that low-watt high-efficiency speaker open-baffle designs are not as welcome there, as they used to be. Indeed, low watt amplifiers have been relegated to the rarest of niches as strange ornaments of times past by the audio community generally. There are exceptions of course, like Nelson Pass's highly praised First Watt, low watt offerings, and excruciatingly expensive Japanese low watt tube designs.

My interest in low watt amplifiers, like my Yamamoto A-O8S 45 Single Ended Triode, began I think, out of a perverse curiosity to find out why, when I was avidly reading about audio several years ago, so many older audio enthusiasts were so vocal that low watt amplifiers can potentially deliver magic to recorded music. The idea being that a simple circuit has less chance of messing things up. In the case of a Single Ended Triode design, letting the output tubes and transformers create their magic without unnecessary interference.
hard

It is gratifying to encounter someone who has experienced the joy of flea power.  There's a whole world of magic to be encountered in the world of single ended tube amps capable of delivering 2 watts or less (both triode and pentode) in combination with very high efficiency speakers (especially if the latter are used in a near-field arrangement).  Like everything else in audio, it's a matter of individual taste; and, many just can't accept that a 1 watt amp can play more loudly and cleanly into a high efficiency speaker than a 100 watt amp into a low efficiency unit.  I do many demonstrations of the former and never disclose details to listeners until after they have had a chance to experience the sound.  The look of pure astonishment on their faces when they find out they were listening to flea power is worth the effort. 

roscoe65

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Re: My Low Watt SET amp & High Sensitivity Speaker Journey ~
« Reply #7 on: 18 Dec 2017, 01:04 am »
It's puzzling to me that in almost 2018, there is so few choices in solid, low-cost streamers that offer coax spdif output. 
Like most audiophiles, I already own high end DAC's and would like a good streamer that has good coax spdif out.  If no coax, would take regular toslink preferably over mini toslink, and analogue outputs are not needed. 

Looking around, I might just have to pick up Chromecast Audio unless there are better options.. :scratch:

While it isn’t coax SPDIF, the Nvidia Shield TV outputs high resolution via USB.  It’s currently selling for $149.  With the recent news that Deezer will support Chromecast, you would have at least two FLAC services to choose from.

ohenry

Re: My Low Watt SET amp & High Sensitivity Speaker Journey ~
« Reply #8 on: 18 Dec 2017, 02:08 am »
I have a few flea amps and really enjoy them.  I bet there are many of us lurking with sweet and simple tube amps (maybe not as nice as Richard's  :green:).

BTW, if you want to try a cool speaker that's cheap and easy to make, grab a set of Saba console greencone drivers (woofer and tweeters) from the 1950's.  I have mine mounted in simple floorstanding, open-backed plywood boxes using one cap for the tweeter crossover.  They are efficient and sound great with sane decibels.  I got mine from a German guy on ebay and they are in excellent condition.  I suppose it makes perfect sense they get along well with low power tube amps.  :D

I have three Chromecast audio units streaming Tidal hifi.  Again... another good sounding, cheap thrill.  I bought some decent 3.5mm to RCA plug ICs on Amazon and it's fun to sit back and dream of different music to play.  It's a nice way to discover/investigate music before investing in vinyl or CDs if you're like me and addicted to tangible formats.

-Richard-

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Re: My Low Watt SET amp & High Sensitivity Speaker Journey ~
« Reply #9 on: 18 Dec 2017, 07:36 pm »
Sorry to hear that you are not able to spend more time listening to music, Bemopti123, which everyone in our audio community knows sustains a vital sense of being connected to life and the mystery of deep 'listening'. I have my audio set-up in my main 'living space', which also serves multiple purposes. Also my painting studio and Deborah's studio are open to this 'living space' so I can play the music even while we work. I am fortunate that Deborah loves music at least as much as I do and was even responsible for my continued interest in low watt SET tube designs. She finds most solid state amplifiers agitate her. When I listen to music 'directly' I sit off-axis reclining on a couch. This is one of the unique benefits of Open Baffle speaker design, the presentation penetrates the entire room, allowing for the luxury of off-axis listening pleasure without necessitating having to sit in front of the speakers. I hope you can get back to your listing pleasure soon.
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What have you replaced your Coincident amplifier with, Wind Chaser? The Aurarlic Aries Mini is highly regarded, a nice set-up indeed! Of course you are spot-on, this is really a wonderful time to be involved with audio.
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Tidal is probably the best streaming service available right now, roscoe65. How interesting that you are using Chromecast Audio: https://store.google.com/product/chromecast_audio I have never heard of it before. How did you manage to get a discount on Tidal for only $8 per month? That is a lovely deal! Tidal is running out of money? How strange, it sounds like their must be some problem with their business model. Tidal is the premier streaming service that every audio reviewer is in love with. Yet, and this is peculiar, I tried it during their introductory free month and found it sounded lifeless on my audio set-up. I think using the built-in EQ on Spotify can add juice to the music. And it may be that 'juice' that is creating the special dimension that the music has in Spotify that lends itself to my set-up. However, I should revisit Tidal again when I have the chance.

You are quite right about the limitations of streaming. When I hooked-up my CD player a while back I was shocked at how much musical information it allowed compared to streaming; it was also wildly more dynamic, stunningly so. However, my current set-up is so revealing that all of the warts came through as well from this admittedly low-end CD player; there was a significant lack of refinement that I could never live with, a certain crudeness that accompanied the presentation. I would have to invest in a very sophisticated CD player to get the incredibly dynamic presentation without the noise. Something beyond my present budget. The lack of 'noise' allows Spotify streaming to sound remarkably transparent, something I crave and because of it, the music sounds more like it is coming from an electrostatic speaker.
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I had to look up S/PDIF (Sony/Philips Digital Interface Format), Jon L, "The signal is transmitted over either a coaxial cable with RCA connectors or a fibre optic cable with TOSLINK connectors." Can you share with us what advantages this has over standard RCA interconnects? Also, what would be the advantage of Chromecast Audio over streaming Spotify from an iPad?
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Thank you FullRangeMan. I like your idea of no crossovers and (apparently) no tweeters. Keeping things simple really works for me.
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Nice insight, belle harbor; it seems that as solid state amplifier designers were delivering amps with more and more watts, speaker designers got a little lazy and moved away from working with high-efficiency speakers. Admittedly, there are serious problems designing with high efficiency speakers. My own system using a Lowther Alnico driver played 'full-range' but augmented with a 15" bass speaker which cuts off at around 250Hz and having its own dedicated amp, is no where near 'perfect'. There are anomalies that appear from time to time. I am certain the frequency gamuts are not flat through the entire range, for example, as I use the EQ on Spotify to enhance certain frequency gamuts. Although there is a great deal of work done by speaker designers to flatten the frequency response of their speaker designs, it is not entirely clear if this is ideal. For example the classic BBC speaker design used a 'bump' in the lower gamut, somewhere around 250Hz, I think, to create 'warmth' in the presentation. As you said, it is a matter of individual taste. It also depends on what kind of music one listens to most of the time. Deborah and I love small scale ensemble classical music from every period, including jazz and especially the great women jazz singers, like Holiday, Vaughn, Horn, Gardot, Fitzgerald, Simone, Wilson, Washington, and so many other magnificent singers like Sinatra, Baker, Cohen, Lennon and Mathis. It is a trade-off I am willing to accept for the 'magic' of what the system gets right, wonderful detail without any etching, deep saturation of musical color and texture, and a nice dose of ambient 'space'.
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Nvidia Shield TV is also new to me, Roscoe65. I have not watched TV for over 40 years but Deborah and I are filmophiles and share a love and passion for film. Can you share with us something about it?
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I can see your love for 'tangible' media, ohenry, although my budget for all things related to audio and music has shrunk over the years. And of course tangible media needs well designed players to sound at their best, another major expense. I can see why vinyl has such a renewed resurgence over the past 10 years, I love the feel of LP's and handling them has its own charms. However, I also remember trying to poise the needle over the subtle 'empty' grooves between songs, or parts of a sonata in order to just play that section; rather time consuming, requiring great care. There are many drivers from the 1950's that have never been bested! Really, a golden age for audio. My first audio system used a pair of open backed boxes, each with a single Wharfedale coaxial driver, driven by a tube receiver. Essentially, an Open Baffle design. How I loved that sound! That early system enhanced my love of music and broadened my musical tastes and enjoyment beyond measure.

With Warmest Friendship ~ Richard


 

rollo

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Re: My Low Watt SET amp & High Sensitivity Speaker Journey ~
« Reply #10 on: 5 Jan 2018, 05:17 pm »
 Nice system Richard. I joined the party with Rethm Saadhana 102db wideband speakers and Dennis Had SET [5w]. PP I use an Audio Hungary A20i integrated.


charles

-Richard-

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Re: My Low Watt SET amp & High Sensitivity Speaker Journey ~
« Reply #11 on: 6 Jan 2018, 08:18 pm »
Hi Charles ~

I cannot think of a more sophisticated design than the Rethm Saadhana, or a more sophisticated hi-end audio designer than Jacob George in India. He is a US trained architect and his design studio in Kerala is quite superb looking! He started with Lowther drivers but his work-around issues trying to tame the British driver to fit his cabinet design led him to start fresh with his own completely redesigned drivers. Now that is a true high-end uncompromised design approach. I would love to hear your system. Nice!

With Warmest Friendship ~ Richard

FullRangeMan

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Re: My Low Watt SET amp & High Sensitivity Speaker Journey ~
« Reply #12 on: 6 Jan 2018, 11:18 pm »
Wow very nice Yamamoto :thumb: