[corndog71]

I'm not really complaining about my current performance.  They still sound amazing.  A little more impact would be nice.  2 more drivers would be nice.  As Ric alluded to, it never ends. 

[mlundy57]

Desire may never end but funds certainly do. My mother always said I had champain taste on a beer budget 

Mike

[Ric Schultz]

Just use two or three layers of the wool felt you can get in a fabric store.....works fine.

[HAL]

YMWV (Your mileage will vary).  Hal's system is nothing like anyone else's here nor will it ever be anything like what you are using.  He has digital eq., op amp amps for each driver, wires all over the floor.....stuff everywhere and changing daily.  The only true pure A/B was done by Jay....he got more output and better sound by having them all go forward (crossed over at 70Hz!!!!).  Please, try this yourself.  You are the only one that can know the truth.  As more and more people do pure A/Bs in the same system we will all know the truth.

Do not discount the sound of a system you have never heard.  Nothing changes daily in regard to the servo sub array running up to 150Hz. 

Build a DC coupled, balanced input amp, with no Zobel or Thiele network needed for stability directly driving a planar driver.  To bad most folks will never try it, when it is a great sounding match. 

And for DSP, you have never heard this unit using balanced connection to the HX800 amps.   Beats any passive crossover I have heard, and I have listened to a large number of them in 40 years of this hobby.

Good luck.

[gregfisk]

Yes, of course, it is better to have all the drivers in the same direction.  It is even more important with those with Wedgies, Super Vs, Serenity 7s, Hawthorne open baffle speakers, etc. that cross over higher in frequency.  And just as important in these same speakers would be to physically align the voice coils of the main speakers to the woofers.  By having both (or all three) woofs all facing forward and physically aligned with the main speakers the sound will be tremendously better.  Also having no H-frames but using straight baffles or U-frames would also make the sound better.  Why would you want the lower midrange to come out of some square tubes? Serious resonance problems there.  If you cross the woofers in at 70 or below then the H-frame is probably doing no damage.....but above that frequency?  You have to be kidding!!!!!!  Seriously bad!!!!  You guys with Wedgies, Super Vs, Serenity 7s, Hawthornes...need to turn off the upper drivers and listen to the woofers by themselves....you will hear voices, all kinds of midrange sounds....these things are only crossed over at 12 db per octave.....they go way up in the lower midrange.........the speakers need to be open to blend perfectly with the higher frequency drivers....not stuffed back in square tubes.  Think about it.  Try it!!!!!!!!  I would never ever use H-frames above 70hz....never.  And having the drivers face different directions....this is just plain wrong.  And every speaker I have ever built sounds best with the woofers and the upper drivers physically voice coil aligned.

Rick,

Shouldn't you be spouting all your (absolute facts) on your own circle? Oh, that's right you don't have your own circle. So, what speakers do you manufacture again? I own Super V's, do they sound good? Yes, very good. Would they sound better with both woofers facing one direction? Maybe, would they sound better if you designed them rather that Danny? Not a chance it hell is my guess. But the fact is, I haven't heard any of your speakers so I don't really know. Kind of like you don't really know what Hal's speakers sound like, I don't either. I just don't understand how you get on a circle that someone else pays for and knock his design desicisions. I mean, what gives you the right to do such a thing. This is his circle and his business and their's nothing that annoys me more that someone trash talking someone Else's lively hood.

[Ric Schultz]

Hal, I don't discount your system, I bet it is wonderful.  But you have not done a proper A/B of the drivers in both configurations and using them in the way ALL others would be using them....this is my point.  If you turned around every other driver and had them all facing forward you could listen and tell us what you hear on your system.  I bet you would be mind blown at how much better they would be.........then if you made a super dead, super braced open baffle or U-frame with all 6 on them I bet it would be even better.  You cannot know anything unless you experiment.  And the experiment has to be done very cleanly.....everything the same each time, etc.

Greg, I am not "trash talking" anything.  I am offering suggestions based on years of listening.....and now backed up by one of the GR Research users.  People take things so personally.  This is not personal.  Danny decided long ago that his open baffle servo woofs would face in both directions because someone else said it was a cool idea.  He did not listen each way and decide for himself....we all do this.  I have done this tons of times.  We are all.....always learning. We cannot try everything nor do we have the time nor inclination.  Personally, I am always open to suggestions.  I know I know nothing.  We are a single grain of sand compared to the knowledge of the universe.  I offer my ideas to help people get better sound.   So far, everyone who has tried my ideas has found them to be valid.  Danny cannot know everything nor try everything.  Hopefully, he is open to bettering his products....hopefully, he is listening to what I say with an open mind and heart and not taking what I say personally.  Danny is wonderful, and a wonderful designer.....but he is human, just like you and me....so always learning.  Greg, want to learn something?  Turn around the driver facing backwards....then time align them with the coax....and get back to us.  You cannot learn unless you try something new.  My ideas are not mine.  I did not invent anything here.  I just have information based on direct experience that I am sharing that hopefully will help people get better sound.  I hope you share information that helps people.  This is how we all grow.....in the Love together.

[bdp24]

I admit to feeling conflicted. I understand, sympathize with, and share the impulses of Hal and Greg, while at the same time thinking Ric's answer is a good one. But I always want to know the "why" of something. I don't know for a fact that Danny automatically put the drivers in his H-frame reversed, without trying them both facing forward, and I don't know for a fact that they sound better---or even different---so facing. The fact that Ric does, does not make it a "fact" just because he says so. He may think it does because he thinks it should, ya know? That's not unheard of in audiophilia .

My drivers are still in W-frames (I haven't yet built the great H-frames I got from Jay---can't wait!), in which the drivers MUST face the way they do, and which no less a technical expert than Seigfried Linkwitz says has resulting sonically-relevant advantages. Yet with all Seigfried's knowledge, Danny designed a better H-frame than did SL, didn't he? And better full-range speakers too, in the opinion of many here. That's because Danny has a designer's mind and an audiophile's ear, a rare combination.

Danny has on occasion corrected Ric on a technical matter, explaining why he is "wrong" in one of his design elements. While I appreciate and admire a highly-developed ear, an ear informed by technical knowledge---if the ear is not thereby made deaf by preconceived notions and/or conclusions---is a very powerful design instrument. No disrespect intended, Ric! You are the ultimate audiophile, and I benefit greatly from your no-holds barred, no-compromise, extreme-even endeavors at achieving excellence in music reproduction---very noble endeavors in my book. I wince when I see or hear Hi-Fi referred to as a "hobby". Music and it's reproduction means far too much to me to use that belittling and demeaning term in relation to Mankind's most sacred and important art form. I think that we all agree on, ay?

[Early B.]

One thing to understand is the mind of a designer. Here's an example -- Danny has already stated that one of the reasons he reversed the woofers is for weight distribution. Now imagine the pain and sorrow and repercussions of a young child tipping over a GR Research subwoofer onto himself or another child due to inadequate weight distribution. And to compensate for uneven weight distribution may require a higher cost, an "unreasonable aesthetic" or a more difficult DIY design merely for a slightly better sound, if what Ric is saying is true.   

My point is that there's lots of other non-sonic considerations that a designer isn't gonna use a forum to attempt to explain because it sets himself up for another round of second guessing by audiophiles who aren't proficient in speaker design, manufacturing and marketing.   

[HAL]

The W frame will be a good test against the other two cabinet styles.

It keeps the driver centers aligned and has the force cancelling effect.  Nice that it is also shorter than the other two cabinets as well.

Another way is simply taking the Super-V's and compare to two stacked 1x12's both facing forward as the bass section.  That is also a direct AB comparison.

[Captainhemo]

Ric if you go back and read post 109 (your post) on the previous page,  if that isn't bad mouthing   Danny's designs, I don't  know  what is. Maybe it wasn't intended to come across like that, but I'd say it did.  There are a lot of very happy customers out there with  the designs you mentined, don't think I've ever heard a complaint about any of them.
That being said, I do agree with you that  the only way for  people to know what the difference is, is to actually try, without doing so, it's hard to say what  a person  will hear or feel.
As I mentioned, I was never the slightest bit  disappointed in either the duals or triples with a reversed driver,  my reason for  doing the latest build with all 3 drivers facing forward was  for appearence and also because I had a  few people ask me just how unbalanced the cabinets would be if they were to  have  the drivers all face forwards... I didn't really know so I tried it.
There is a difference in stability, you can tell they are   more  rear  weighted if you push on them... will they tip over,  no not unless a deliberate  attempt is made to  tip  them... the same could happen with a standard  version.
I was surprised  when I noticed some sonic differences using the same 6 drivers  and same amps with the  settins  untouched, I had simpoly swapped the drivers from  one pair of cabinets to the other

Saying people will be blown away by the sonic differences is a huge  exaggeration IMO. Do  I hear a difference,  yeah, a bit more  impact/focus and an icrease in output (I had to reduce the gain on each A370 by 3 or 4 clicks).  Am I blown away, no but I will say I'm pleased with the unexpected result

Rich,  would be cool  for you to try a couple of your modules with both  facing forwards as you mentined, wouild love to know results

jay

[HAL]

Jay,
Looking at rewiring the servo subs, so the A/B would be doable.

And as far as the 6x12 H frames, there are two pairs I know of made by Ruben.  Both are running last I heard.  The second are mated to the BG FS880's that Danny designed mods for.

[Ric Schultz]

Actually, Hal has half his drivers reversed.....so putting them all forward will really make a more noticeable difference than what you heard....assuming the same use.  Others, that cross over higher will also hear much more difference.  The fact that you are crossing over at 70 and it makes a noticeable improvement means that crossing over higher will really make a serious difference.  And again if they physically align voice coils with phase set to 0 degrees there will be more difference and again more difference if they use an open or U-baffle. But these are just words. The only one that can know is you.

One of the reasons I sometimes use exaggeration is to put a fire in your arse.  Most people won't do anything unless you shout at them and take them to church. Really, it is up to you to pursue better sound or not.  Some have the finances, some don't.  Some have the desire, some don't.  Some like to experiment, some don't.  Some people will take what I say personally.  Some just want to argue and make drama.  I want to help people get better sound.  I have no financial stake in whether or not you have better sound.

You say reversing one woofer out of three makes a noticeable difference crossing over at 70hz......I say, this is just the beginning.  I hope some more people will try reversing, physically time aligning and open/U-baffles and hear for themselves and report back.  I have no more to say on the matter.  It is now up to you all.  You either drink the water nor not.  Bless us all.  The water is yummy!

[Danny Richie]

Yes, of course, it is better to have all the drivers in the same direction.  It is even more important with those with Wedgies, Super Vs, Serenity 7s, Hawthorne open baffle speakers, etc. that cross over higher in frequency.  And just as important in these same speakers would be to physically align the voice coils of the main speakers to the woofers.  By having both (or all three) woofs all facing forward and physically aligned with the main speakers the sound will be tremendously better.  Also having no H-frames but using straight baffles or U-frames would also make the sound better.  Why would you want the lower midrange to come out of some square tubes? Serious resonance problems there.  If you cross the woofers in at 70 or below then the H-frame is probably doing no damage.....but above that frequency?  You have to be kidding!!!!!!  Seriously bad!!!!  You guys with Wedgies, Super Vs, Serenity 7s, Hawthornes...need to turn off the upper drivers and listen to the woofers by themselves....you will hear voices, all kinds of midrange sounds....these things are only crossed over at 12 db per octave.....they go way up in the lower midrange.........the speakers need to be open to blend perfectly with the higher frequency drivers....not stuffed back in square tubes.  Think about it.  Try it!!!!!!!!  I would never ever use H-frames above 70hz....never.  And having the drivers face different directions....this is just plain wrong.  And every speaker I have ever built sounds best with the woofers and the upper drivers physically voice coil aligned.

Actually the complete opposite is true. You never want to use them on a flat baffle especially one no larger than the size of the woofers themselves. By doing this you have no real front to back wave separation. So you are reducing your output in the lower ranges considerably. You also create a peak in the response in relation to the baffle size. And the woofers can much more easily reach full X-max as there is zero additional loading of the drivers.

Also to create a cavity resonance within the space you'll need to produce a wave length short enough to propagate within the 13" square space. That would be wavelengths higher than 1kHz or so.  They don't play that high.

Even if you look at the H frame as a port the tuning frequency is very high. It would probably fall in the 500 to 600Hz range.

So your concerns are not really valid in this application and you're killing your bass response by the use of the flat baffle.

[Ric Schultz]

Danny,
I had two of your servo woofs on an 18 inch wide 2.25 inch thick baffle and measured flat at 20 hz in my room.  How low do I need?  I heard nor measured any peaks.  Obviously, you have more extreme low frequency output and more headroom in an H-frame.  Depends on the size of the room and how loud you listen whether or not you would ever reach the limit.  If you use U-Frames then you are more than half way there....and also if you needed more output then use more woofs.

[Danny Richie]

There also seems to be some confusion here regarding time alignment. There is physically aligned and then there is acoustically aligned.

Just because something is physically aligned does not mean it is time aligned. The reason being is that other things in the signal path cause a shift in phase or time delay. So you can have a pair of drivers physically aligned but the use of a first order crossover can put them 180 degrees out of phase at the crossover point.

And if you have a passive crossover on your upper set of drivers it doesn't matter weather your subs are physically aligned or not. The inductor inline with your mid-bass driver caused a big shift in phase. And it doesn't matter whether it is a Neo 10 or a woofer. The inductor will cause a lag. So if you want to ignore the phase control on the servo amp and align the acoustic output then you might find that the subs need to be four feet or more behind the plane of the speakers to time align them at the crossover point. The distance will depend on how high the crossover point is. Or you might need to move them out in front of your main speakers.

Fortunately the servo plate amp has a phase control that will allow them to be blended from almost any location.

Now as for the woofer facing one way or another and whether they are time aligned or not and what difference it will make. With one woofer flipped the amount of offset of the voice coil at 20Hz is less 1/100th of the wave length. So the phase rotation is less than 1% on a low frequency note. Think you can hear that? The amount of phase rotation goes up with frequency but we are still talking about ranges from 1% to 8% of phase rotation. That is laughable compared to the amount of time delay, peaks, and cancellation you get from the room reflections of those low frequency waves. The reflection can be anywhere from 0 to 180 degree out of phase and everywhere in between.

So chances are that you are more likely to make a greater difference by moving your subs back or forward 6" to a foot than you are trying to keep the voice coils aligned.

Now technically it can make a difference if the voice coils are aligned. It will keep them more in phase for sure, but keep some prospective. Let's say you have a mid and a tweeter that is in perfect time alignment at a given height or distance between the two of them. Move your seating height up 6" and now they are no longer in perfect phase. One arrives in time before the other. You are creating 1% to 8% of phase rotation or more and in a MUCH more sensitive range. And I can tell you for certain that most mid to tweeter combos are very rarely in perfect time alignment at the typically measured tweeter axis or at an on axis response. There is very often 10 to 20 degrees of phase rotation going on between the drivers.

[bdp24]

Actually the complete opposite is true. You never want to use them on a flat baffle especially one no larger than the size of the woofers themselves. By doing this you have no real front to back wave separation. So you are reducing your output in the lower ranges considerably. You also create a peak in the response in relation to the baffle size. And the woofers can much more easily reach full X-max as there is zero additional loading of the drivers.

Also to create a cavity resonance within the space you'll need to produce a wave length short enough to propagate within the 13" square space. That would be wavelengths higher than 1kHz or so.  They don't play that high.

Even if you look at the H frame as a port the tuning frequency is very high. It would probably fall in the 500 to 600Hz range.

So your concerns are not really valid in this application and you're killing your bass response by the use of the flat baffle.

Here we have a perfect example of something significant. I have absolutely no doubt, yes, even without hearing it, that the difference in sound between mounting the drivers on a flat baffle rather than in an H-frame is far, far greater than the difference between having all drivers facing forward. The former will create a huge disadvantage (against the flat baffle), the latter a perhaps slight advantage (in favor of it). If you want to use a flat baffle, it obviously needs to be of sufficient width to achieve the same front-to-back distance between driver centers (to prevent opposing polarity cancellation) as is achieved in the 16"W X 14"D H-frame. The flat baffle (even at 2-1/4" thick) will then require robust bracing to equal the non-resonance achieved in the frame by nature of it's construction. You gotta first get the basics correct before you sweat the details.

[Danny Richie]

Danny,
I had two of your servo woofs on an 18 inch wide 2.25 inch thick baffle and measured flat at 20 hz in my room.  How low do I need?  I heard nor measured any peaks.  Obviously, you have more extreme low frequency output and more headroom in an H-frame.  Depends on the size of the room and how loud you listen whether or not you would ever reach the limit.  If you use U-Frames then you are more than half way there....and also if you needed more output then use more woofs.

Yes, they will still try to maintain a flat response. That is what the servo control system does. But if you try to push them to higher SPL levels you'll run out of X-Max real quick. And the system is probably using a lot more of its headroom trying to control the overshoot. So it is having to slam on the electrical brakes pretty hard to keep control. You're probably down to half or a third of the output you would have with a H frame in the first octave or two.

Take away the servo control and you will no longer maintain a flat response, or have any low end output, plus bottom out the woofers a lot more easily.

[fliv]

Hello Everyone,

[fliv]

Hi Everyone,

Just wanted to post a picture of my system with a pair of Jay's flat pack dual OB subs. I have an old (1966) set of Altec Valencias in which Danny helped me upgrade the x-overs. I am running first generation Dodd Audio 120 monos and a Dodd mid pre. They sound great with the new subs. Thanks To Jay and Danny for all the help.

Fliv

[Danny Richie]

Nice amps Fliv.

You might want to try pulling those woofers further out into the room. You should get a lot better results that way. Some room treatment will go a long way too.

Thanks for posting the pic.