Here's another email that I received recently. Thought I'd answer it in the forums, since there's a lot of people building speakers with waveguides, and tapped horns.
Hi Patrik.
I'm writing you for several reasons..
Lately I've been working of building a pair of tapped subs - well they're on the drawing board... And since you have a lot of experience on the area I hope that you can guide me in the right direction because on the other hand I've been thinking about going the multisub route. I know you've done both, so which do you prefer for a home theater solution? are the taped subs superior or are they just "fun to talk about and build"
My opinion on subwoofers has evolved over the past few years. I built my first bandpass sub nearly twenty years ago, and my first tapped horn in 2007. Here's the thread:
http://www.diyaudio.com/forums/subwoofers/114340-tapped-horn-dummies.html
My first tapped horn was a disappointment. It didn't go as low as I'd hoped, and it was a lot of work to build.
Here are some things that I learned from building a few of them:
So do I like tapped horns? Yeah, definitely. But keep in mind that they're just a glorified dual-reflex bandpass. If you don't have the tools to measure the impedance curve, I'd stick with a sealed box.
It's interesting that Bose has switched from a dual-reflex bandpass to an offset transmission line. This is quite close to a TH.
As far as multiple subs go, that's a no brainer. I could never go back. I'd take three cheap subs over a single good sub any day. Or better yet, three good subs.
Another thing that I'm curious about are the "Summas". Initially I wanted to build a pair but ended up building a pair of 7Pi Cornerhorns insted. Now I'm considering building them again and just wanted to ask you what makes them so special.. I owned a pair of Sp technology Continuum AD once so I know something about the waveguide theory.
Yes, I'm very happy with them. What makes them so special? Well they have all the advantages of mini monitors (imaging, tonality, low fatigue) but without the disadvantages (power compression, lack of dynamics.)
Generally I've found that horns excel at dynamics, but they're difficult to listen to for a long time. Even the horns I've built myself, for my car, suffer from that. The research that Geddes invested in reducing HOMs is clearly doing something right. The Summas really aren't competing with other horns; to me they sound like conventional hifi speakers, but *without* the drawbacks. They don't sound *anything* like horns.
Thirdly I'm curious about the Unity secrets. Are they such a delicate matter to build? How does one figure out location and size of the midrange holes? And if its 3-way (Danley SH-50) - what about the woofer placemant, holes ect...
Hope for some guidance🙂
Yes, the Unity is probably the most complex loudspeaker I've ever seen. I guess that's why it's so interesting to me. Compared to a Unity horn, and tapped horn is child's play.
There are a *gazillion* variables in a Unity horn. The location of the midrange holes is just the tip of the iceberg.
The easiest ways to understand the way that a Unity works is to understand that a Unity horn is simply a three-way array that has been folded around a horn. The same rules that apply to a direct radiating array apply to a Unity horn. In particular, it's important to understand that you need to get the drivers in an array within 1/2 to 1/4 wavelength. (This is the reason that D'Appolito arrays don't perform so hot; the driver spacing is too large.)
For instance, if you want to get a seamless crossover from the tweeter to the midrange, and the crossover is 1600hz, you need to get the drivers within 2.1"!!! (13500 inches per second / 1600hz /4)
That's the most critical challenge in a Unity horn. The spacing of all the drivers and the crossover points are all inter related.
The Unity horns is particularly well suited for nearfield listening, because of the tight spacing of the midranges and the tweeters.
A lot of people ask why a Unity horn doesn't use direct radiators. The spacing is the reason. You can't get five drivers that close together if they're direct radiators.
Once you start grokking the dimensions here, it becomes obvious that lowering the crossover point will make life a lot easier. And that's why the Synergy horn uses a coaxial compression driver IMHO.
HTH!
Hi Patrik.
I'm writing you for several reasons..
Lately I've been working of building a pair of tapped subs - well they're on the drawing board... And since you have a lot of experience on the area I hope that you can guide me in the right direction because on the other hand I've been thinking about going the multisub route. I know you've done both, so which do you prefer for a home theater solution? are the taped subs superior or are they just "fun to talk about and build"
My opinion on subwoofers has evolved over the past few years. I built my first bandpass sub nearly twenty years ago, and my first tapped horn in 2007. Here's the thread:
http://www.diyaudio.com/forums/subwoofers/114340-tapped-horn-dummies.html
My first tapped horn was a disappointment. It didn't go as low as I'd hoped, and it was a lot of work to build.
Here are some things that I learned from building a few of them:
- Hornresp exaggerates the peaks and the dips. Don't obsess over getting the flattest response possible.
- Designed properly the efficiency advantage of a TH is very real. I built a front loaded horn and a TH to test this out, and found out that the TH had as much as a 10-12dB advantage at certain frequencies. And it played lower.
- A properly designed tapped horn can be more efficient than a FLH or a bandpass. But a bandpass and a FLH can sound 'cleaner' because the enclosure rolls off the highs. So it's a tradeoff - it's more efficient but it can sound "grungier."
- I've found that there are three things that can make a TH sound better. The use of multiple woofers smooths out the response, and the use of shorting rings or an underhung motor reduces distortion. These improvements also apply to FLH and bandpass, but they're more audible in a TH due to the lack of a coupling chamber. (Yes, you *can* put a coupling chamber in a TH. But I've never seen anyone do it.)
So do I like tapped horns? Yeah, definitely. But keep in mind that they're just a glorified dual-reflex bandpass. If you don't have the tools to measure the impedance curve, I'd stick with a sealed box.
It's interesting that Bose has switched from a dual-reflex bandpass to an offset transmission line. This is quite close to a TH.
As far as multiple subs go, that's a no brainer. I could never go back. I'd take three cheap subs over a single good sub any day. Or better yet, three good subs.
Another thing that I'm curious about are the "Summas". Initially I wanted to build a pair but ended up building a pair of 7Pi Cornerhorns insted. Now I'm considering building them again and just wanted to ask you what makes them so special.. I owned a pair of Sp technology Continuum AD once so I know something about the waveguide theory.
Yes, I'm very happy with them. What makes them so special? Well they have all the advantages of mini monitors (imaging, tonality, low fatigue) but without the disadvantages (power compression, lack of dynamics.)
Generally I've found that horns excel at dynamics, but they're difficult to listen to for a long time. Even the horns I've built myself, for my car, suffer from that. The research that Geddes invested in reducing HOMs is clearly doing something right. The Summas really aren't competing with other horns; to me they sound like conventional hifi speakers, but *without* the drawbacks. They don't sound *anything* like horns.
Thirdly I'm curious about the Unity secrets. Are they such a delicate matter to build? How does one figure out location and size of the midrange holes? And if its 3-way (Danley SH-50) - what about the woofer placemant, holes ect...
Hope for some guidance🙂
Yes, the Unity is probably the most complex loudspeaker I've ever seen. I guess that's why it's so interesting to me. Compared to a Unity horn, and tapped horn is child's play.
There are a *gazillion* variables in a Unity horn. The location of the midrange holes is just the tip of the iceberg.
The easiest ways to understand the way that a Unity works is to understand that a Unity horn is simply a three-way array that has been folded around a horn. The same rules that apply to a direct radiating array apply to a Unity horn. In particular, it's important to understand that you need to get the drivers in an array within 1/2 to 1/4 wavelength. (This is the reason that D'Appolito arrays don't perform so hot; the driver spacing is too large.)
For instance, if you want to get a seamless crossover from the tweeter to the midrange, and the crossover is 1600hz, you need to get the drivers within 2.1"!!! (13500 inches per second / 1600hz /4)
That's the most critical challenge in a Unity horn. The spacing of all the drivers and the crossover points are all inter related.
The Unity horns is particularly well suited for nearfield listening, because of the tight spacing of the midranges and the tweeters.
A lot of people ask why a Unity horn doesn't use direct radiators. The spacing is the reason. You can't get five drivers that close together if they're direct radiators.
Once you start grokking the dimensions here, it becomes obvious that lowering the crossover point will make life a lot easier. And that's why the Synergy horn uses a coaxial compression driver IMHO.
HTH!
out of curiosity, are crossovers in summas a kind ofa hi-pass filter, i.e. a 15" driver plays freely, unfiltered?
I haven't looked at the schematic recently. (The crossovers for both speakers have been posted in this forum BTW.)
Another nice thing about The Summa is that all the parts are readily available. For instance, if you purchase an Avantgarde horn, you're dependent on them for a lot of the parts. Everything in the Summa can be acquired from USSpeaker or Parts Express.
Except for the cabinet of course.
and except for the summas WG. before we try other WGs on the market we will never know how much of its sound belongs to geddes OS horn.
would be VERY interested in having a peep into the schematics but i think i have never seen such a post here. any chances you have a link?
would be VERY interested in having a peep into the schematics but i think i have never seen such a post here. any chances you have a link?
Why "we will never know how much of its sound belongs to geddes OS horn"? The information is there now or you can just come and listen to them. I would agree with John in every aspect - the details of what I do make a big difference, And its not just the waveguide, remember the foam plug, which is now covered by a patent, thats a very big part of differences in what I do and others, among other things.
The Summa schematic is proprietary, it third order HP and LP, but nothing standard by any means.
John has had his speakers now for - four years? I don't hear him saying that he wants to swap them for anything else.
Do the speakers of AudioKinesis and Pi Speakers obtain the same sound as Summas or Abbeys? (non horn like)? They don't use your waveguide, and they do not use foam.
Pi speakers
I've build the 7Pi's. They sound like horns but most definently without listening fatigue as many others. If the sound could be of your likings I could'nt say.
I've not heard the Summas nor Abbeys but like to...
I've build the 7Pi's. They sound like horns but most definently without listening fatigue as many others. If the sound could be of your likings I could'nt say.
I've not heard the Summas nor Abbeys but like to...
I've heard all those speakers, but I'm biased. They are similar to my designs, but not as refined. Lets just say they definately don't measure as well - that isn't biased, its simple fact.
Does flat frequency response equal great sound.....
I hope I dont beaten by saying that flat frequency only exist at zero reflection distance from the speaker. I've also done a lot of measuring in my livingroom and once measurements are taken from my sweet spot things look a hole lot different.....
I think thet many would agree with me when I say that the most important measurement tool are ears;-)
I hope I dont beaten by saying that flat frequency only exist at zero reflection distance from the speaker. I've also done a lot of measuring in my livingroom and once measurements are taken from my sweet spot things look a hole lot different.....
I think thet many would agree with me when I say that the most important measurement tool are ears;-)
Great sounding speakers do not always have great FR plots....Some flat FR response speakers can sound like crap too.
there is more to a great sound then just FR plots.
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Could you please clarify this.
Folks have been stuffing foam into horns (and around horns) for decades. You were able to get a patent on this?
This is curious!
Yes the patent number is 7,708,112. It references all the available prior art from UREI, Meyer, etc. and one particuraly close application by Long, but none of them were broad enough to cover what I do.
Flat "polar response" equals good sound. Room measurements don't mean much unless you do them right, and know what to look for, otherwise they are just a "random" set of data. Best case they can be useful, but hardly sufficient. Worst case they are totally pointless.
Ears are hardly an infallible judge of sound quality - remember that there is a brain involved, and that dominates the situation.
My only gripe is that they're SO DAMN BIG 😱
In all other respects, they're great. I brought them out to the DIY fest on Mercer Island last year, but not sure if I'm up for the challenge this time.
I wonder if it would be possible to replace the woofer with a neodymium model? That would make them a heck of a lot more portable. The woofer alone weighs 36lbs.
Patrick
For all practical purposes the Summa, as you have it, is obsolete and I probably won't make anymore. This is for all the reasons that you state.
Neo pushes the price up quite a bit for no audible improvement only weight - most people don't move them arround so adding this cost for everyone is kind of a bad idea. But I might. The new cabinet material is such a vast improvement over anything that I have done in the past that if I do get orders for a Summa I'll just use the poly, which has to be 1/4 the weight of what you have (box only). So a new woofer and poly cabinets would redice the total weight by probably 1/2, which is worth doing. But they are still going to be BIG - there is no way arround that when using a 15" and 18" waveguide.
For all practical purposes the Summa, as you have it, is obsolete and I probably won't make anymore. This is for all the reasons that you state.
Neo pushes the price up quite a bit for no audible improvement only weight - most people don't move them arround so adding this cost for everyone is kind of a bad idea. But I might. The new cabinet material is such a vast improvement over anything that I have done in the past that if I do get orders for a Summa I'll just use the poly, which has to be 1/4 the weight of what you have (box only). So a new woofer and poly cabinets would redice the total weight by probably 1/2, which is worth doing. But they are still going to be BIG - there is no way arround that when using a 15" and 18" waveguide.
Yeah. If I were to replace these speakers, I would likely replace them with an Abbey.
It's fun to take them to DIY shows and the like, because people have never heard anything like them.
Ok - there must be a point to this somewhere - I read the link - but I'm missing it. Can you fill me in?