[RodMCV]

Hay Bob,
I have just noticed that Nuforce is selling a new speaker the S-1 to go with their neat new Mini amp.

I have been informed that you designed this, I thought so!

Don't keep quiet on this.

How did this come about and is it like your other wave guides?
I can't wait to hear it. Nuforce and you do it again!
Another out of the box wild looking Speaker with SP Tech design written all over it.

I hope this catches on with Joe consumer and not just computer geeks
 as this might lead more unsuspecting music lovers back into the
Wonderful World of the SP Tech and Nuforce Family of Sound Quality Products.

Rod

[Albireo]

I've been listening to the S-1 for the last week and it's frightening how much of the Timepiece Mini/S-9 signature it delivers! The S-1 simply sounds live like no other desktop speakers I've owned, including the Audioengine A2 (which I loved and which tided me over for ... well, a long time, until I got my Minis). In fact, I'd go so far as to say it sounds more live than anything I've owned except for the Mini/S-9. It is somewhat held back by the smoothly rolled-off Icon DAC/amp (actually, I think it's the USB DAC doing the roll-off more than the amp), but without knowing the response of the driver I can't say that wasn't a good design choice. In any case I hope to do a more comprehensive comparison shortly.

[Aether Audio]

Hey Rod,

   Yeah, I designed the passive part (the speaker proper) part of the S-1.  NuForce designed the active Waveguide Compensation filter into the Icon though.  It made more sense to put the filtering there than build a passive filter into every enclosure.

How did this come about and is it like your other wave guides?

Well, since the S-9 turned out pretty good I guess NuForce figured that a small waveguide based desktop might just be the ticket.  They asked me and I agreed so the rest is history.

As far as the waveguide in the S-1 being the same as in the S-9 and our stuff goes... well, sort of.  Basically, I applied the same principles to a different driver is all.

Albireo

The S-1 simply sounds live like no other desktop speakers I've owned...

Thanks!    Now you all know why Bob Smith will never design a speaker that doesn't include a waveguide - assuming performance is an issue at some level.  You watch... it won't be long and everybody and his brother will be hawking speakers with waveguides.  Just remember who started it all when they do!

Take care, 
-Bob

[konut]

With all due respect, Bob, Earl Geddes claims to have applied the term wave guide to loudspeaker applications in the early '90s. Prior to that it was a term used in microwave transmission and reception. Having said that, Dr Geddes adamantly states that a true wave guide is an oblate spheroid.  The term wave guide is thrown around pretty commonly these days. This is not to take ANYTHING away from you, Bob because the geometry of your horn is unique. It IS the secret to the success of your designs. I'm not ashamed to admit that I've spent more than a few hours just looking at it. It is not only a triumph from an engineering perspective, but a work of practical art! I wouldn't be surprised if more speaker manufacturers beat a path to Bobs door to work on designs for them.  :not worthy:   

[WGH]

With all due respect, Bob, Earl Geddes claims to have applied the term wave guide to loudspeaker applications in the early '90s. Prior to that it was a term used in microwave transmission and reception.

1984 Acoustic Waveguide
Bose designs acoustic waveguide technology and brings component system sound to a compact system. Experience full sound from an extremely small enclosure.
http://www.bose.co.uk/GB/en/about-bose/milestones/index.jsp

[konut]

I stand corrected! Who wants to break this to Earl? 

[Aether Audio]

Konut,

While I agree that Mr. PHD Geddes was the first (maybe) to use the term as applied to horn theory, I was building them.  In the early '90s I developed the first Timepiece (1.0?) - we just called it the Timepiece back then.  I was demonstrating the first prototypes to our little "speaker building club" that Bruce Bartlett (Crown Mic designer and recording engineer), Jim Wordinger (Crown amp designer), Dave Harris ("Bassbox" speaker design software developer) and myself (the "Pres"  ) started at the Crown facility - and that before Earl published his paper "the Oblate Spheroidal Waveguide in the journal of the AES.  As an intersting side note, the 5 of us tried to get "the one and only" D.B. Keele to be an "officer" of our club as well, but he was too busy - but he came to the meetings! 

Anyway...back to the subject.  As another intersting little "tidbit," I had thought of and implemented the concept of matching the radiation pattern of the woofer to that of the tweeter at crossover around the same time Earl proposed the idea.  The only difference was the he was "somebody" and published papers while I was "nobody" and just built the things - and that not knowing a thing about his proposal at the time.

You might find it intersting to note that there was this young engineer (can't remember his name now days) that had a paper published in the AES Journal a month or two after Earl's paper that took a really good stab at Earl's idea.  Through the math (WAY beyond me) he showed that the OSW was nothing more than a CD horn.  Of course, Earl surely did and still would take issue with that guy's argument, but it does give one cause to stop and ponder.

Nevertheless, we'll give Earl credit where credit is due - he probably was the first to at least popularize the term.  But even then, there were these guys working for Kenwood that wrote a paper using the term as applied to tweeters and it was before Earl's.  They built this "little thing" that they showed was able to reduce/eliminate tweeter diffraction artifacts.  It was their paper that gave me the idea to pursue the waveguide approach and I had already built and tested two different prototype speaker systems using them before Earl's OSW paper was published.  Oh... and this was all before Genelec, Mackie or any of the other pro monitor companies where marketing systems using waveguides.

So... who's on first?  I wish I had half the brains Earl does, but the way I figure it, what's more important...talking about a thing or doing it?  "Faith without works is dead" is the doctrine I try to live by.  SP Tech may not even be the first to have started producing a product based on waveguides, but I suspect that we've gotten more "milage" out of the device and refined systems based on it to a higher degree of performance than virtually anybody else. 

I guess I'm just hoping that folks remember that when they start seeing them popping up everywhere - which you will.  At some point you either evolve and follow the trend or get left behind.  Most recent and previous to the waveguide was the ceramic and diamond driver rage.  First there where one or two companies using them, then everybody climbed on board - now even B&W!

Once again, the "smarter" companies will be the first to use waveguides and many of the "holdouts" will go the way of the dinosaurs.  Just ask Darwin if you don't believe me. So there... that's my profoundly prophetic utterance for the day.

Take care,
-Bob

PS.  The Bose claim is for their bass reproducing system.  It all started with their "Acoustic Cannon" tube device.  Since then the mathematical models have been extended to include the "6th order" dual-port bass box design.  It has nothing to do with tweeters or high frequency applications.    But... maybe they were the first to use the term. 

[konut]

Thanks for that facinating history and correcting my misinformation. Always glad to be "set straight"! 

[Russell Dawkins]

I believe Genelec was talking about waveguides (and using that term) as early as 1983 and producing them in 1985: They were using them for both the mids and highs, although the efficacy of the shape and size for the frequency range covered by the midrange driver is questionable in light of current thinking:

http://www.genelec.com/company/genelec-story/

[WmR]

The term "waveguide" goes back to the late 30's and early 40's with radar.

Even in the early 50's, most University labs had "plane wave devices" and it was referred to as a "waveguide".

For a loudspeaker application, it really does not matter who is first using the term. What matters is who is using the technology with APPLICATION in a commercial venture. The only speaker I saw with a "shallow conical device" being sold commercially and in many stores before discovering Bob and SP Tech was Cerwin Vega. This was 1993--







I do believe if it were not for SP Tech, the term would be collecting dust and you would not see so many loudspeaker companies out there playing "copy this guy".

We can all credit Blumlein ("Bloom-line") with the level of engineering that started the cascade. Unfortunately, killed while working on a Churchill radar project.

Just my opinion. I may can be proven wrong.

[phoenix_rising]

   Yeah, I designed the passive part (the speaker proper) part of the S-1.  NuForce designed the active Waveguide Compensation filter into the Icon though.  It made more sense to put the filtering there than build a passive filter into every enclosure.

Just ordered a pair in NZ should be here next month, thought you had a hand in them, hopefully you are getting something for each unit sold. Speaking of which when are you going to put our your general consumer line ?

Phoenix

[Russell Dawkins]

directed at WmR:

I was not, in my post, referring to Genelec as the outfit that first used the term, but that actually had speakers in production with what they called a waveguide - and this was 1985, not 1993.

Remaining slightly OT for a moment, the "waveguide" employed by SP Tech is far from shallow and raises the question of the definition of waveguide, vs. what is commonly called a horn. I'm not aware of a definitive distinction between the two.
It seems recently to have been well established that a horn does not intrinsically have an unpleasant sound characteristic, so for all I know this could be a great sounding horn.

For the record, a BBC recording engineer I met - who would have been old enough to associate with engineers who worked with Alan Blumlein - called him "Blum' lin" with a short "u" and "i".

[konut]

I think that the term "waveguide" is being used generically by manufacturers to avoid the word horn and any pejorative connotation that horns have aquired over the years. Horns have evolved over the years, from the earliest days of audio, and have become more refined as the math and measurement systems have caught up to the materials and electronics. Part of the problem is that certain geometries are more focused on sound reinforcement applications and consumers incorrectly assume that these types of horns will also be appropriate for home use. Even some major equipement manufacturers are guilty of this. One size does not fit all, so to speak. Earl Geddes maintains that it is only the oblate speriod shape that minimizes HOMs, or high order modes. As I understand it, and I could be wrong and frequently am, high order modes are generated because the point of origin, tweeter, compression driver, etc, do not generate perfectly spherical wavefronts so that sound is reflected off the walls of the horn in an other than ideal manner. Whatever. The proof of the pudding is in the eating, to use a well worn phrase. As Bob uses a horn with a unique geometry, it might be appropriate for him to use a unique term for his horn. Just a thought. aa   

[WmR]

directed at WmR:

I was not, in my post, referring to Genelec as the outfit that first used the term, but that actually had speakers in production with what they called a waveguide - and this was 1985, not 1993.

Remaining slightly OT for a moment, the "waveguide" employed by SP Tech is far from shallow and raises the question of the definition of waveguide, vs. what is commonly called a horn. I'm not aware of a definitive distinction between the two.
It seems recently to have been well established that a horn does not intrinsically have an unpleasant sound characteristic, so for all I know this could be a great sounding horn.

For the record, a BBC recording engineer I met - who would have been old enough to associate with engineers who worked with Alan Blumlein - called him "Blum' lin" with a short "u" and "i".

On pronunciation, I am actually going by a BBC documentary with people who actually worked with the man, but they actually could be in error perhaps.

If you like, I can upload the programme somewhere for you if you have space for it. It is however, 56 mins. A one time use, for educational purposes, of course.

December 1933, stereo was demonstrated. It is included in the show (audio only)
As mentioned earlier:

The term "waveguide" goes back to the late 30's and early 40's with radar.

FWIW

This old reference from 1956 goes into detail about waveguides.
I have a well worn hard copy, had it for close to 40 years.


http://www.questia.com/PM.qst;jsessionid=LyLZTvJ0G2sG825DQtQvWG6H6WYnT1nMwg2M5YQbfxWQvJpLJ2Lk!-109120824?a=o&d=99334266

[RodMCV]

Hay,
Just saw a reference to your design in the 6moons Icon S-1 completed review.
Right-ON Bob!