[-Richard-]

Several months ago I decided to throw caution to the winds.

After being an Open Baffle enthusiast on the cheap for 10 years, I purchased a pair of Lowther PM5A Alnico/Ticonal drivers from Lowther America working with Jon Ver Halen. Jon is a wonderful person to work with, very knowledgable and not afraid to share what he knows. I also purchased a Yamamoto Sound Craft A-08S Single Ended Triode 45 tube amplifier directly from Shigeki Yamamoto, the Japanese master, working with him through emails. Yamamoto no longer has a dealer in the US. Since the pair of Lowthers I purchased are 15 ohm, I asked Shigeki to use a 16 ohm output transformer so there will be an efficient match between his 45 amplifier and the Lowthers. I wanted to be able to potentially use every trace of the 2 watts the 45 tube could deliver.

I was a little nervous not knowing if the 2 watts of the A-08S could adequately drive the Lowthers. The Lowther site in England states the Lowther PM5A is 96 db sensitive. “They measure a little differently over there than we do, Richard. I would say the sensitivity is closer to 98 or 99 db”, Jon reassured me. Jon was right, I need not have worried. This combination can play very loud without distortion, much louder than I would ever want to play it.

When I was ready to purchase the PM5A's, Jon told me that he had a Ticonal version of the Alnico magnet and wanted me to have it, which made me intensely excited. I had heard a great deal of praise about this extremely rare, legendary and apparently out-of-production version of the Lowther Alnico magnet which contains an added ‘secret’ ingredient of magnesium. “Fantastic ambient retrieval” Jon suggested.

Srajan of 6 moons suggested that the Yamamoto A-08S has a ‘modernized’ application of the original 1930’s SET circuit that leans closer to a solid state perspective than a design that renders a ‘romantic' tube experience. The speed of the Yamamoto A-08S made me think that the Alnico magnet might be a good match with its emphasis on ‘ambient’ retrieval over the more detailed presentation offered by the Neodymium or Ferrite magnets used by Lowther. There was some controversy about Shigeki’s use of the DC heaters in the circuit in the newer S version of his 45 SET. Some purists and other SET designers felt that it may not express the ‘tone’ of the original circuit which uses AC heaters. Srajan wades in, "By DC-coupling the 45s and 717A drivers, noise levels for the revised amp are given as 0.3mV to 0.7mV. Tonal qualities of the A-08S are now felt to be superior even to the very best 300B amps. Further "S" changes include a switch from the 5U4G to the 80 rectifier which was developed in tandem with the original 45s way back when. To the designer, this presents a logical marriage of vintage origins.”

The A0-8S is shockingly quiet. The music is cast against an infinitely quiet background with a clearly articulated textural presence. The sense of ambient space around instruments and voices revealing the presence of the room in which the music was recorded is stunning. Combined with the Lowther PM5A, the tonal presentation is surreal and fully saturated. And yet I think it is the harmonic complexity, the subtle inner-detail, the shimmering after-sounds that reverberate after a string is bowed or plucked, or a cymbal is struck, or as the breath is just leaving a clarinet, or any other wind instrument, or the subtle modulations of the voice as the sound is shaped by the lips and tongue, as well as the explosive sense of immediacy and suddenness when an instrument or voice begins to sound, that creates the uncanny effect that nothing is separating you from the music spilling into the room.

We are speaking of music expressed through many different musical forms, the emotional intensity of classical Japanese singing with Koto accompaniment, the ancient imperial court music of gagaku, the Blues of John Lee Hooker, late Mozart quintets or the late quartets of Shostakovitch, Miles Davies’s Kind of Blue, Billie Holiday and Melody Gardot, classical Dhrupad chanting, the emotional power of Nina Simon, the contemporary work of Arvo Part, especially his subtle choral works, Julia Kent or Osvaldo Golijov, everything comes to life.

I also decided to re-design the Open Baffle panels by cutting them down to a visually satisfying minimum. Deborah chose an off-white color to paint them that she felt would go nicely with our new pickled-oak laminate floor. The scale of the new panels is so easy to live with; they are extremely light-weight, easy to move around, and the off-white color Deborah chose sets off the whiter, yet still creamy-colored Lowther drivers. Nice!

Like most of our DIY Open Baffle community I am using what I have on hand to fill-in for the rest of the system. A few years ago I purchased the small Milllenia TBI class-D 7-watt amp as a back-up to substitute for my problematic Heathkit re-designed tube amp, until I was able to figure out what to do next. I was not ready for major research nor a major purchase at that time. I now use the Millenia as a dedicated amplifier for the Eminence 15A bass drivers. I dusted off the original passive preamplifier made by Luminous Audio, really a voltage regulator, that I used for all of my previous SET amplifiers, to work as a volume control for the Yamamoto.

The Lowther’s are known for long 'break-in’ periods and my experience was not different, although within 3 months of modest playing things smoothed out nicely. The Yammie also needed time to ‘break-in’, so I let them ‘break-in’ together.

At first I used my mass-produced, cheap, rather un-refined, but dynamic CD player. Then I began to use an older iPad Mini to stream from Pandora. Pandora's streams sounded remarkably good through the iPad Mini with admittedly some loss of detail, until about 2 weeks ago when they ‘upgraded’ their web site and the ‘spatial’ presentation I heard before disappeared and in its place was a hard flat dimensionless musical landscape. I jumped into Spotify to see whether it could sound better. After signing-up for the Premium service I chose the highest resolution stream, 320 kbps, that they currently offer.

I began to stream music into my new system and was immediately stunned. What I heard, and continue to hear, is the most exquisite musical presentation I have ever heard from an audio system. Deborah was even more stunned than I was. She commented, “It is like the music explodes into the room, creating its own sense of space, sounding exactly like the instrument or voice, with incredible excitement!”.

Before I switched to Spotify I liked the new set-up and thought it sounded comparable to the new Magnapan .7 drivers Deborah and I heard a few weeks ago in a showroom in LA. But with the music now streaming from Spotify at 320 kbps, through my lowly iPad Mini with a built-in DAC that probably cost only a few dollars, the sound is utterly mind-glowingly fantastic. Any of the usual considerations about audio, how well it does this or that, now seems totally irrelevant.

Of course it is the Open Baffle paradigm that allows the music to launch into 'aliveness' in the way that it does. The way that the sound impregnates the air of the room and encourages it to burst into musical life. As Deborah suggested, the dynamic presentation literally leaps beyond any perception that the music we are listening to is recorded and being re-created by mechanical devices. Everything sounds utterly alive!

We are obviously happy with our set up as it is right now. However, there is room for improvement. For one thing, Luminous Audio now offers a very sophisticated version of their original passive preamplifier, which I am tempted to purchase. I am using a pair of NOS RCA 45 tubes purchased several years ago and there is a consensus that the gigantic EML 45 tubes sound even more dynamic. The interconnects and speaker cables are not necessarily designed for the Yammie, Lowther combination. The Millenia may not go down as far, perhaps, as a dedicated plate amp might, and I am using a simple coiled inductor to cross-over the Eminence 15” drivers at 250 Hz, which may be detracting from the performance of these modest drivers. A dedicated plate amp with a high cross-over option might work better, although be less convenient to adjust ‘on the fly’, being usually relegated to the back of the panels.

The Lowther PM5A’s loses its low end rather higher than I would have expected, due no doubt, to the small baffle area it now resides in. And just as strangely, the lowly Eminence 15” drivers easily and seamlessly blend with the Lowthers so that from the midrange on down the sound is fast, rich, ripe and musically satisfying. There is absolutely no sense that the music is being presented from a divided source.

I like the ability of ‘shaping’ the sound somewhat by going back and forth between the passive preamplifier for the Yammie A-08S and the volume control on the Millenia. For example, I simply add the perfect amount of bass I want after I first choose volume on the passive preamplifier. It is almost like a tone-control. I read an interesting article many years ago that suggested that there is a see-saw inverse relationship between the bass and treble; add more bass and the treble seems to lose some of its sparkle, add more treble and the bass seems to lose its role of creating the music’s foundation. I find that this equation proves quite true with this set-up. Still, there is some wiggle-room. I can add just a little more bass when I want it, or a little less and achieve a perfect match for any music without canceling out the perception of the lowest bass or highest treble the current set-up can deliver.

The cost of these 2 purchases, around $2500 each, is over $5000, and does not reflect why many of us were originally so intrigued and attracted by the inexpensive entry point of a DIY Open Baffle solution as a serious approach toward one’s audio and musical dreams. What prompted me to spend the money was a feeling that I have reached an age where I want to live with audio products that I truly love; love for their design philosophy, their looks, as well as their performance potential. I get just as much pleasure looking at the Lowthers and Yammie amplifier as I do to listening to the gorgeous music they help to bring into my life. Also, the thought that the Yammie is performing its amplifier role with just 2 watts is still hard to believe, and is a source of delicious bewilderment.

One thing I was hoping for before I purchased the new amp and drivers is that it would be capable of resolving small scale instrumental music, like string quartets. I am happy to say that it succeeds beautifully, the strings have a sweetness usually missing from many audio systems that tend to harden the sound of bowed violins, making them sound brittle, and so lose the lovely subtle harmonic resonance that a bow sliding across the taught strings of a violin, cello or bass can create.

Our musical experience has now leaped from sounding reasonably good to sounding other-worldly thanks in a large measure to Spotify. And it may be interesting to note that the equipment used to feed the Maggies the day Deborah and I auditioned them, was well above $15,000, and that was without the cost of the Maggies themselves.

So-called hi-end commercial speakers and amplifiers that tout their pedigree and are offered at astronomical prices cannot deliver more music satisfaction then I am currently hearing with our relatively modest DIY Open Baffle system. Our current system is the result of what I have learned from playing around with the Open Baffle paradigm for several years, including the shared experiences of our wonderful community in this AudioCircle open baffle chat room, and of course, just simple luck. I cannot express the fun and enjoyment at having been able to slip out of the addiction of purchasing commercial speakers, with their carefully crafted illusion that one must spend more in order to achieve higher performance. I cringe to think what hi-end equipment with the added cost of a dealers mark-up would get for a set-up that sounds this good.

I am now wondering what further performance enhancements could be achieved using Tidal, with its lossless streaming format, or one of the other new high-resolution streaming services, and a well-designed, although not expensive DAC. Perhaps the soon to be released Aurilic Aries Mini at $400? To say that we DIY Open Baffle speaker enthusiasts are lucky to be alive right now, with incredible audio products and high-resolution streaming music services, is an understatement.

I photographed Deborah standing next to the new baffles for scale. Their new modest size is surprisingly able to penetrate the room with an immediacy and richness that makes people ask when they visit us, "where is the sound coming from.” When I point to the Open Baffle panels they look at them in disbelief, “the sound seems to fill the room and be everywhere”, one of our friends suggested.

Happy listening. If things change for the better I will keep you updated, just for the fun of it. With Warmest Friendship ~ Richard

[Bemopti123]

I can only imagine how fantastic it all sounds.  Congrats, you have been at this for a long time. 

Paul from NYC

[Docere]

Hi Richard,

I don't spend much time over here. I would love to try open baffles as you have done, but sadly, my room just won't support it. I am rather envious - I bet it sounds at least as satisfying as you describe it.

I'd like to clarify something in your post. Srajan often presents incorrect technical details. This statement, technically makes no sense: "By DC-coupling the 45s and 717A drivers, noise levels for the revised amp are given as 0.3mV to 0.7mV". In "coupling" terms, DC means direct-coupling between stages- the Yammy is not directly-coupled. In electrical terms, DC means direct current. The Yammy does, as you state, use direct current for the 45 tube filaments. I would be surprised if direct current was for the 717A heaters (they use indirectly heated filaments, where DC would provide little to no benefit if implemented correctly). That is academic though; what is important is...

... that your system is lovely (to my way of thinking). Relax and enjoy your achievement.

Cheers,
Ray

[MJK]

If I understand your post and the pictures of the back of your OB speakers, you are using only a coil in series with the Eminence woofer and nothing else as a crossover?

Are you running the Lowthers full range?

How are you matching the different SPL/W/m values for the two drivers?

[mcgsxr]

Richard, always a pleasure to read a post of yours.  Your ability to convey both the inspiration, and the outcome of your system is always a wonderful experience!

I am enjoying the Crown XLS 1500 pro amp at the moment.  They are readily available, and going cheap these days (~$200 or so).  They have a built in Xover, and gain pots.  It could prove a useful affordable option for your bass drivers.

Have fun, and thanks for sharing!

[bladesmith]

Nice, simple, clean. Looks like a coil for a "low pass" filter, on the lower driver and a full range driver, above. I know a lot of people here, like that kind of a simple set up for the cleanest, least encumbered sound possible.

Very nice....!

V...

[MJK]

The cleanest sound you will get from a Lowther driver in an OB is with the low frequency content removed, in other words using a high pass crossover.

A lot of money was spent on Richard's system but without a properly designed crossover and some boost for the Eminence I think he has really handcuffed the potential for great sound. He may like what he hears now, but it could be a lot better. I built my first Lowther OB speaker over 10 years ago and have messed with baffle sizes, different woofer combinations, and  with and without crossovers and have concluded that the crossover is required and getting it right is critical.

[bladesmith]

Just wish I could get my system as simple as yours...

Very envious....

[MJK]

And you could help, for a few dollars more, right ?

This is DIY, I am offering an opinion and recommendation based on my experiences. I have no interest in doing the work for others, Richard needs to do the work himself.

Based on the tone/insinuation of your comment I guess it is best to keep my opinions to myself from now on.

[Brad]

Martin, please don't keep your comments to yourself.

I'm sure Richard will appreciate your thoughts.

[-Richard-]

I am currently using a simple coiled inductor to fade the frequencies above 250 to 300 Hz for the bass drivers that I had around from previous driver combinations. The Lowther’s are allowed to play full-range.

I see, Martin, that you are suggesting the use of a filter to fade out the lower frequencies of the Lowther’s. The small baffle area the Lowther’s now occupy seem to be doing some of that through natural cancellation.

The bass drivers can certainly use a boost to help with the cancellation inherent with OB designs. Even box-speaker designs like Harbeth have used the 'BBC-boost' in the low frequencies for years to give a sense of warmth and fullness to the bass.

I am hoping that as streaming software becomes ever more sophisticated and the providers are willing to cater to audio enthusiasts, they will design high-resolution EQ options into their formats. Apple has a simple EQ option available with iTunes that one can play with to see what effect it can have on speaker performance, just to get a sense of it.

I would suggest that there is a ‘base’ performance level to one’s set-up that can sound to us quite satisfying. From there we can tweak our hearts out, depending on our budget of course. ‘Better’ is like the word ‘more’. Assuming that there is not a dynamic being played out psychological of an inner-feeling of being impoverished, ever pushing one toward the need to fill-up a gnawing sense of lack, such as people experience who overeat, experimenting with one’s set up to derive more musical satisfaction seems worthwhile and can be fun.

However, we can certainly ask ourselves, what is the ‘sound’ we are looking for? If one reads audio reviews for any length of time, reviewers often describe a speaker designer as having a 'house sound’. Until this present set-up I would have had no idea what ‘sound’ I was actually looking for. Now I do. It is the burst of excitement that accompanies the sudden appearance of the musical sound, whether instrument or voice, a deep textural resonance that renders an authentic sound of the material of the instrument, and the visceral sense of decay where the sound lingers in the ‘air’ as overtones, a kind of splashing of tonal resonance, that for Deborah and I, draws us deeper into the musics mysterious space.

I think the idea of musical ‘space’ is worth talking about. What distinguishes what I am hearing now from previous explorations into the DIY OB paradigm is how the music penetrates into the space of the room, how it stimulates it, so that it now sounds like it has taken possession of it. There is no part of our house that the music does not penetrate when it is playing. If I was to fancifully imagine a sexual embrace of sound and space, I would say the music sounds like an ardent male lover who has taken complete possession of the feminine ‘air’, they are locked in an embrace that helps to transport one into the mystery of what makes music so enchanting, and even at times transcendent.

Thanks Mark, for the suggestion of the Crown XLS 1500 pro amp. I briefly looked at it and it may be exactly what I am looking for. I need a little time to further explore it.

I hope that as a community, each of us can feel entirely free to share our opinions with each other. My knowledge of speaker design is minimal, especially compared to Martin, and so many of you on this wonderful Opened Baffle forum. I am here to learn and to share whatever I am experiencing that I think might be interesting to us as a community, as we continue to probe our way into the mystery of musical reproduction within the DIY Opened Baffle approach.

Happy Listening. With Warmest Friendship ~ Richard

[rajacat]

Martin, please don't keep your comments to yourself.

I'm sure Richard will appreciate your thoughts.

+1

[gab]

I am currently using a simple coiled inductor to fade the frequencies above 250 to 300 Hz for the bass drivers that I had around from previous driver combinations. The Lowther’s are allowed to play full-range.

I see, Martin, that you are suggesting the use of a filter to fade out the lower frequencies of the Lowther’s. The small baffle area the Lowther’s now occupy seem to be doing some of that through natural cancellation.

I hope that as a community, each of us can feel entirely free to share our opinions with each other. My knowledge of speaker design is minimal, especially compared to Martin, and so many of you on this wonderful Opened Baffle forum.

Richard - please do read Martin's piece here if you haven't already: http://www.quarter-wave.com/Project10/Project10.html

It could lead you to perform a few low cost crossover changes that should further improve your system.

gab

[MJK]

I am currently using a simple coiled inductor to fade the frequencies above 250 to 300 Hz for the bass drivers that I had around from previous driver combinations. The Lowther’s are allowed to play full-range.

I see, Martin, that you are suggesting the use of a filter to fade out the lower frequencies of the Lowther’s. The small baffle area the Lowther’s now occupy seem to be doing some of that through natural cancellation.

The bass drivers can certainly use a boost to help with the cancellation inherent with OB designs. Even box-speaker designs like Harbeth have used the 'BBC-boost' in the low frequencies for years to give a sense of warmth and fullness to the bass.

The Lowthers have a sensitivity of ~98 dB as stated in your first post. The Eminence woofers have a sensitivity of ~92.5 dB in an infinite baffle, probably below 90 dB in your OB. So you have about a 10 dB mismatch.  It you try and boost the Eminence that much you are going to run out of displacement, you probably need two woofers per side.

The SPL output from the Lowthers is rolled off by the narrow baffle, this probably starts in the 100's of Hz range. But the displacement of the Lowther resulting from low frequency signals is not rolled off. In a boxed system the tuning of the TL or BLH will tend to attenuate the Lowther cone displacement at the bass frequencies, the box exerts a back pressure that works against the driver motion. In your OB system this is gone so any low frequency input getting to the Lowther will cause cone motion even if you do not hear the sound.

So without a high pass crossover the mid and treble that the Lowther produces so well will be superimposed onto any bass driven cone motion. If 40 Hz bass is being fed to the Lowther the cone motion will be large and depending on the input power may produce displacement at or exceeding Xmax. If you add the crossover the low frequency content is filtered out and only the mid and treble is being produced by the Lowther cone. I think it is obvious that an appropriate crossover will help improve the clarity of the Lowther. If you were using a higher powered amp I would be worried about significantly degraded performance and potentially damaging the Lowther driver if a real bass heavy recording was playing without the protection of a crossover.

So my advice is to design an appropriate low and high pass crossover in the 100 to 400 Hz range respectively. I think that you are going to need to attenuate the Lowther output a lot to match the single Eminence woofer or a little and add a second woofer. You are probably getting away with your set-up because the amp has a very low power rating.

If you go the route of a passive crossover on the woofer and the Lowther you may run into trouble with your tube amp. I have tried a tube amp in this type of set-up and it did not seem to like the load from the low crossover and the bass disappeared, a SS amp worked great. If you remain passive consider upgrading your amp to a SS unit with a little more power.

[MJK]

Double post.

[-Richard-]

You are probably getting away with your set-up because the amp has a very low power rating.

There are quite a few audio aficionados who feel that the Yamamoto A-08S should sell for $15,000, or even more. Before I purchased it I was coveting the Nelson Pass First Watt SIT 1, SS amplifier. It cost $10k and Srajan feels it really reaches its full potential when mated to a direct-coupled SET tube preamplifier that itself cost over $10k and is no longer in production. So to replace what I think the Yammie is doing so well with something comparable in the SS world could easily cost over $20,000. Of course there are less expensive SS amps that are probably very sophisticated with a rich tonal perspective.

Single Ended Triode tube amplifiers, if designed well, do not sound exactly like other tube circuit designs. And the Yammie does not sound like other 45 tube SET designs I am familiar with. I have owned, and auditioned in my home, several well designed varieties on one or another of my previous OB iterations. I am not saying SET circuit designs are the final word in amplifier design. Every design does some things very well and given the right speakers and ancillary equipment can bring the music to life.

I am familiar with the web page that showcases your formidable OB design using Lowthers and 2 large drivers for the bass. I am certain they sound quite convincing and very satisfying.

Before I started teaching art and design full-time at Parsons School of Design in New York City, I was a working designer for many years. My sense of design is simple, 'less is more'. Or as Albert Einstein once said, 'make things as simple as possible, but not simpler'.

It is in the light of that sense of loving things that are simple, that I brought together the Lowthers and Yammie, to see how they would get along, and whether or not they could make music together. I am grateful that they work well together.

Admittedly, I have little interest in pushing an audio set-up past a certain level of performance, simply because for me it is the music that matters most, and if the set-up honors the music I am quite satisfied although I am comfortable with a little tweaking here and there. And yet having said that, I could just as easily have dedicated my life to being an audio designer. It is great fun and it is not, fortunately, rocket science; it is approachable and its intricacies can be deciphered with a little diligence. I did design a few well-known audio products over the years, at least the visual look of them.

The point I am trying to make, Martin, is why would I want to 'fix' something that works?

There are many audio designers, I have known them and worked with them first hand, who would not listen to gear they design unless it looked right to them on the oscilloscope. I can tell you that it did not always work to their products advantage.

Happy Listening. With Warmest Friendship ~ Richard

[MJK]

The point I am trying to make, Martin, is why would I want to 'fix' something that works?

To make it work better.

You seem to be focused more on cost and name recognition than design and performance. To spend all that money on drives and fancy tube electronics and then pay almost no attention to the connection and distribution of the signal seems very inconsistent.

Personally, I don't care about looks or name recognition. I want the best performance I can achieve for the dollars I have available and using my own design capabilities.

[D OB G]

Just a thought Richard.

You could fit an appropriate high-quality capacitor to the Lowther on one side.
Then you could take some time to appreciate any differences.
Technical issues would be secondary to your actual enjoyment.

Regards,
David

[matevana]

To make it work better.

You seem to be focused more on cost and name recognition than design and performance. To spend all that money on drives and fancy tube electronics and then pay almost no attention to the connection and distribution of the signal seems very inconsistent.

Personally, I don't care about looks or name recognition. I want the best performance I can achieve for the dollars I have available and using my own design capabilities.

100% Agree with Martin

[mcgsxr]

Suggestions are nice, but it sounds to me like Richard is happy.

i remember visitors telling me I should install some kind of filter on my b200 Visatons when I ran them.  I thanked them for the idea.  I did not think anything needed changing.