[Duke]

Hi Audiovista/Boris,

I hope I didn't come across as proclaiming "this is the Last Word on the sealed vs vented" debate.  I certainly don't expect anyone else to just take my word - but since what I describe was my personal experience it carries a lot of weight with me.

I think that vented boxes quickly earned a poor reputation due to manufacturers desiging them to either play the numbers game or impress with a boom-and-tizz presentation that becomes tiring over any audition longer than the ten minutes it takes the salesman to close the sale.  Vented boxes were strictly against my religion for many years, and even today I'm more likely to enjoy an average sealed box speaker than an average vented box speaker.  There are far more ways to do a vented box wrong than there are to do it right, but done right imho it's a front-runner. 

Duke

[Audiovista]

Hi Audiovista/Boris,

I hope I didn't come across as proclaiming "this is the Last Word on the sealed vs vented" debate. 

NO, NOT AT ALL!!!

I actually appreciate that your post got me thinking about subject that I did not seriously consider for the last 15-20 years. And I just reconciled the current state of affairs at my home, versus what I had a long time ago. As I said, my impression of sealed box superiority was based on what I heard and thought at some point in the distant past. Even though, in time, I acquired almost exclusively vented speakers, that impression stayed with me for a simple reason of not actually thinking about it.

There are far more ways to do a vented box wrong than there are to do it right, but done right imho it's a front-runner.

Absoultely agreed!  Sealed box is a safer bet - and it was even more so when vented boxes were not that well designed/simulated/measured and used almost exclusively to cut costs by enabling small size speakers to output deeper bass, no matter how poor it was.

Tha fact that you are not exclusive regarding the box type (as I once was) gives you a lot of credibility in my eyes.    Not to mention trying to come up with a perfect tube-friendly design.  aa

Best,
Boris

[Duke]

Hi Boris,

Thanks for writing back.

I just checked out your website; frankly I had no idea who I was talking to.  Let me now tip my hat to you on your obviously very well thought-out and engineered tube amplifier designs.

I really like your running that EL84 amp in Class A mode up to 8 watts!  I'd be inclined to think of it as an 8-watt pure Class A amp with an extra 3 dB of dynamic headroom. 

Perhaps the one that fascinates me the most is the little i82MkII.  Under $400 for a single-ended Class A 5-watt integrated amplifier.  Wow! 

Okay, back to the topic of this thread...

I think we're at the point where it makes sense for me to start another thread, offering some further comment on the four within-Duke's-capability proposals that have come up so far, and narrowing it down to the two that I think would be the most promising and practical as far as pushing into interesting and relatively untrodden loudspeaker territory. 

Duke

[Freo-1]

Perhaps the one that fascinates me the most is the little i82MkII.  Under $400 for a single-ended Class A 5-watt integrated amplifier.  Wow!

The Paul Klipsch mantra was as follows: "What this country needs is a good 5 watt amplifier"

Sounds like this little guy would be just the thing for a pair of Klipschorns

[Doublej]

1. A loudspeaker that can be placed against the wall or corners of a room and sound good (think against the wall omnidirectional or polydirectional loudpseaker).

2. A behind the couch loudspeaker. 

3. An above the kitchen cabinet loudspeaker pair that doesn't have a hole in the middle sound due to the large distance (12-15 feet) between the speakers.


These are probably not the types of loudspeakers you want to build but it's what I really really want.





 

[Freo-1]

1. A loudspeaker that can be placed against the wall or corners of a room and sound good (think against the wall omnidirectional or polydirectional loudpseaker).

2. A behind the couch loudspeaker. 

3. An above the kitchen cabinet loudspeaker pair that doesn't have a hole in the middle sound due to the large distance (12-15 feet) between the speakers.


These are probably not the types of loudspeakers you want to build but it's what I really really want.




 

Well, Klipschorns are designed to go into corners, and can sound very good with the right amplification.

[Duke]

Hello Freo-1,

Yeah that little 5-watt amp has got my wheels a-turnin'.  If I was going to do a reasonably-priced speaker to go with that amp - guess what, first thing I'd look at would be exactly the format that Boris suggested:  An augmented wide-band driver.

This might make a great little bedroom or smallroom system.  And then when $ and/or space allows, upgrade to those Klipschorns.

Duke

[Duke]

Hello Doublej,

Thanks for joining in, and for telling us about not one... but THREE speakers that you'd really really want to see. 

I'll come back to the wall-and/or-corner friendly speaker in a few paragraphs - I'll have a lot to say about that one.

The behind-the-couch speaker is a totally new concept to me.  I've never thought about that placement option before.  I take it you have in mind the couch being a few inches out from the wall, and the speakers are between the couch and the wall?  If so, I'm envisioning a wide, shallow box with probably most of the drivers facing up (maybe a woofer down lower that's too wide to fit on the shallow top of the enclosure).   We'd need to pack a lot of output into a format that's just a few inches deep.  On-axis response would be pretty much irrelevant, as we'd be listening to the speakers' reverberant energy only since we wouldn't have line-of-sight to the drivers.   But the power response (summed omnidirectional response) would matter a great deal.  Then there's the effect of the couch itself - if it's a cloth couch it would be highly absorptive, but if it's leather it would be reflective at mid and high frequencies and absorptive at low frequencies.  We'd probably want to protect the drivers from stuff falling onto them off the back of the couch, so grilles of some type would more than likely make sense.   But I don't see any insurmountable obstacles - only some interesting challenges.

Next is the kitchen cabinet loudspeaker pair that doesn't give you a hole-in-the-middle even though they're 12-15 feet apart.  Okay, first let's look what I'd do to avoid a hole-in-the-middle.   Two words:  Toe-in.  (Or, is that one word??)  The way to avoid hole-in-the-middle with two widely-spaced speakers is to toe them in severely.  And in my opinion such speakers should be designed from the outset to be toed in.  This means they should have a radiation pattern that is as uniform as is practical across a wide horizontal arc.  If you don't mind building a kit, Madisound has already designed this speaker.  It's called the "Loki", and uses a Seas coaxial driver.  The coaxial format gives very good pattern uniformity over a wide horizontal arc (something like 110 degrees in this case, if I recall correctly).   Like any speaker they'll have more output on-axis than off-axis, but the output falls off fairly smoothly as you move off-axis so these speakers are very good candidates for an application like this.  Toe 'em in a good 45 to 60 degrees or so.   I currently use the Seas coaxials in speakers of my own design in my home theater system.  This is a product I'm not planning to market mainly because I can't begin to compete with Madisound's kit price; they hadn't come out with the kit yet when I designed mine, so at the time I had high hopes. 

Here's the Loki:  http://www.madisound.com/catalog/product_info.php?cPath=35_40_275&products_id=1688

Just for fun, here's a link to a picture of my Seas-coaxial-based speaker, which I showed alongside the big Jazz Modules at the Lone Star Audio Fest in Dallas last May. 

http://www.positive-feedback.com/Issue31/lonestar.htm scroll down about 1/4 of the way

I call my little coaxial speaker the "Leela".  If you're not a Futurama fan, click on this link to understand why:

http://ng.netgate.net/~mette/fandom/costumes/leela/LeelaOrig2.jpg

Finally, let's look at the wall-and/or-corner friendly speaker.  In my opinion, a design that is going to reflect midrange or treble energy off of a very nearby wall or corner is a mistake (bass energy usually can't help but be reflected off nearby room boundaries).  Research has consistently shown that early-arriving reflections are detrimental to perceived sound quality (this was even shown in research published by the designer of an omnidirectional system).  However - and this is where omnis and bipolars and other polydirectionals shine - an abundance of late-arriving reverberant energy is usually perceived as timbral richness and lushness.  So a polydirectional located some distance from the walls works very well.

In my experience (and I've just recently completed some experiments in this regard), polydirectionals aren't the best choice for a speaker that's going to go up against the wall or in a corner, unless geometrically there won't be additional early-arriving reflected energy.   

Corner placement is even more demanding.  Energy that normally would have gone wide to the sides is now funnelled early into the listening area via the intersecting walls, and this tends to color the sound in undesirable ways.  The answer in my opinion is a speaker whose radiation pattern is no more than 90 degrees wide, down to as low a frequency as the speaker's physical dimensions will allow (directional control requires larger and larger size as we go down lower and lower in frequency - this is why bass horns are huge while treble horns are small).   

In my opinion there's a speaker on the market that's a significant upgrade over the Klipschorn.  It's called the Seven Pi, and uses a much simpler but very effective bass system along with higher quality parts than the Klipsch uses.  It's available in several versions; more information can be found at www.pispeakers.com.

Now if you're looking for a speaker that is either wall-or-corner friendly, then it's got to have the controlled radiation pattern that corner placement calls for along with a bass system whose tuning can be changed dramatically so that instead of becoming boomy with corner placement, it just goes deeper.   I'm already producing that speaker - actually, two of them.  Both my Jazz Modules and my floorstanding version of Stormbringer (which uses essentially the same enclosure) have bass systems that can be tuned from 37 Hz all the way down to 21 Hz by changing the length of the port, and the speaker is -9 dB at 21 Hz with the latter tuning.  Corner loading gives a theoretical +9 dB boost.  I haven't had the opportunity to test the theory because I don't have a room with two usable corners, but it ought to work.  I know they can work well very near corners, tuned to the mid 20's.

Another speaker that works well with corner loading is the Audio Note An-E series.  In fact, I stole my rear-porting configuration directly from them; I just added the user-variable tuning feature (mine uses a modular flared port that can be removed and the port length changed).

Of course, maybe for one reason or another (looks, size, cost) my speakers wouldn't work for somone who's looking for a wall-and/or corner friendly speaker.  Perhaps I should make a downscaled version?

So anyway out of your three suggestions, I see two that I can add to the list of what would be feasible:  The behind-the-couch speaker, and a scaled-down version of what I'm already doing in my current speakers.  The kitchen-cabinet speaker, imho, is already being offered in a Madisound kit, or if you don't want to do a kit, then look into a coaxial by KEF or Tannoy or Gradient.

Once again, thanks for your rich suggestions, Doublej!

Duke

[lonewolfny42]

Duke....
I think Boris is going to RMAF this year...so you guys can compare notes there. Boris does have some nice amps....I've heard them at our NY Rave meetings.
Interesting discussion so far....

                                 Chris

[Duke]

Thanks for letting me know, Chris!  Yup, I'll definitely want to connect with Boris at RMAF. 

Boris, I couldn't find what room you're in from the exhibitor's list.  Please let me know.  I'll be in room 1100, in "The Tower". 

Duke

[Audiovista]

Hi Boris,
....I just checked out your website; frankly I had no idea who I was talking to.  Let me now tip my hat to you on your obviously very well thought-out and engineered tube amplifier designs.....I really like your running that EL84 amp in Class A mode up to 8 watts!  I'd be inclined to think of it as an 8-watt pure Class A amp with an extra 3 dB of dynamic headroom. 

Duke, thanks, you're way too kind. I like your def of i84 as 8W+3dB Cool! 

The Paul Klipsch mantra was as follows: "What this country needs is a good 5 watt amplifier"

Yup, when the Big Guy says so, who am I to disagree  .... But, MF might think that's less than 1% of what you really need.

2. A behind the couch loudspeaker.

I need one too - but subwoofer only, 6-8" deep and it can fire on the narrow end(s) or the wide side toward the wall (or couch, to shake it little during movies... ).
This one is intriguing, what's your take?

I think Boris is going to RMAF this year...

Only as a visitor, new products released too late to make all the arrangements  . But I'll make sure to come to room 1100 and introduce myself.

Boris

[Freo-1]

Hello Freo-1,

Yeah that little 5-watt amp has got my wheels a-turnin'.  If I was going to do a reasonably-priced speaker to go with that amp - guess what, first thing I'd look at would be exactly the format that Boris suggested:  An augmented wide-band driver.

This might make a great little bedroom or smallroom system.  And then when $ and/or space allows, upgrade to those Klipschorns.

Duke

Sounds like an excellent plan to me

[Doublej]

Grand idea for a thread topic

What do you guys think of this?

The challenge: High end sound, extreme minimalism.   No cables, no boxes, no entertainment units or shelving. Nothing but two beautiful speakers.   Two towers, two clean wires out the back you plug in the wall.  That's it

Built into each speaker would be a squeezebox, the amps, etc.  The squeezebox display would be tastefully integrated into the front of each speaker so you could see what's playing.  Absolute minimalism, deadly clean. Zero clutter.

They'd sell.  I know Bang & Olufsen get close to this idea, but they don't really nail it.

To us, hifi rigs are beautiful, but to many, it's an ugly room of cables and boxes and it looks dreadful.   Two towers, two wires, amazing sound.  Design and architectural magazines would be all over them.

/A

It might not be a sound idea to mount the electronics inside, atop or too close to the speakers but it may depend upon whether or not you believe isolation devices are a waste of money. If you believe in them you might need to put your Squeezebox and amp atop a vibraplane shelf mounted in a hollowed out section of the speaker.

[Duke]

I've been busy with show preparations, but wanted to take a moment to rcatch up here.

As I see it, we have six speaker projects proposed that are feasible for me to undertake (obviously sometime after the Denver show):

1.  Boris's augmented fullrange driver speaker - basically a fullrange driver augmented by a woofer and/or supertweeter.  I'd like to keep this speaker under a grand a pair but that's probably not possible; 1.5 grand may be more realistic.  I'd try to do something that would work well with Boris's 5-watt single-ended tube amp.

2.  Scott's tube-friendly first order crossover speaker.  This would be a challenging project, and if successful might be really good.  It would call for some very expensive drivers to do it right.  This speaker would probably end up around 5 or 6 grand a pair with power handling limitations, and around 7-8 grand a pair with very good power handling.  One drawback is the out-of-pocket I'd have to invest in this project; either twice or three times as much as any other, depending on which version we went with.  Also, this would probably have the longest development time. 

3.  Hman's line source speaker that doesn't need a subwoofer.  There doesn't seem to be much interest in this project, so I'm not planning to pursue it.

4.  WEEZ's tube-friendly small sealed-box speaker.  I'd like to investigate a low-tuned vented-box variation before committing to a sealed version, for reasons described elsewhere in this thread.  Also, I personally like higher efficiency not only for amplifier matching but also for reduced thermal compression (greater dynamic contrast).  I haven't talked much about that topic in this thread, but I think it matters.  This would probably be a 2 grand ballpark loudspeaker.

5.  Double-j's behind-the-couch speaker.  Interesting idea, but frankly I think the market is pretty darn small.  This is more of a lifestyle product, and I really don't count those types of customers among my normal customer-base.  So this project would be less attractive to me because I don't think I'd sell enough for it to be worth developing and promoting.

6.  Double-j's wall-and-corner friendly speaker.  Okay, this one interests me a lot.  As mentioned I do a couple of large speakers that fit this description, but a small one might be a very interesting product.  I could make it tube-friendly (seems that's a priority to many people), and it would have to incorporate a highly adjustable bass system (which can be done several different ways).  Not sure of the price range yet, but probably 2.5 grand ballpark.

Any of these prices go up if we use solid wood instead of veneered MDF.  Let's assume solid wood adds 20% to any of these prices.  Is it worthwhile in your opinion? 

Now let me look at these with my industry goggles on.  I have my philosophy about speaker characteristics and priorities, and I have some open slots in my line-up.  The two proposals that are most consitent with my philosophy and would fit best into my present line-up (and future plans) are the augmented fullrange driver and the wall-and-corner friendly speaker.  So in my mind these two are the front-runners.  Some of the other projects are very interesting (in particular the high power handling version of Scott's idea), but I think these two would make the most sense from my perspective. 

Any thoughts?  I'm not dead-set here, and you can sway me.

Duke

[Duke]

I'm back from RMAF now, where I had the immense pleasure of meeting Boris, aka Audiovista.   Thanks for taking the time to come by my room, Boris!

Okay, a rather challenging loudspeaker suggestion was made over in another thread, entitled "What do you like to see next to be developed by a hifi manufacturer?":

Spud wrote:  "How about a speaker which is full range 20Hz-20,000Hz and sells for less than $3500."

I did some modellng and think I can do that, and keep it tube-friendly as well.  Maximum linear output would be around 102 dB (I'm assuming some boundary reinforcement in the deep bass), so this system wouldn't have quite the dynamic headroom of some others.  Above 102 dB and we start exceeding the linear excursion capability of the drivers.  I could make this speaker wall-and-corner friendly, but then wouldn't be able to hit the 20 kHz top end (we'd probably only get up to about 18k or so because a wall-and-corner friendly speaker would have to have good radiation pattern control, which narrows my choice of high frequency drivers quite a bit).  In my opinion, the advantages of radiation pattern control outweigh the loss of the top 1/5 octave of high treble, which I can't hear anyway.

This speaker would be compatible with Boris's amplifiers, but would be priced higher than what most of his customers are probably looking for.  It would be a floorstander. 

Duke