| FlorianO |
Hello all,
This is just a sum up of the information I gathered so far -- mostly from the very kind feedback from Dave and Ron (mostly from this thread: http://www.diyaudio.com/forums/show...&threadid=96999).
All the information here is under the caveat in the subject: Namely I'm a newbie (this is my first speaker build) and I'm just summing up the info avail from more authoritative sources.
1) Building plans
The most up to date building plans for the A126 are avail on Dave's site here: http://www.frugal-horn.com/ronhorns.html.
In that PDF I use the plans on page 3--5 (posted in the full-range.com forum) but with some addded corrections (below).
If I understood it correctly Dave is to redraw the A126 so better plans should be avail soon.
2) Drawings, pictures
I've created a web album at http://picasaweb.google.com/florian...uildingPictures
There are pictures of my 1:1 scale drawing of the horn profile with corrected metric dimensions (in mm). The assumed building material thickness is 18 mm.
3) CC volume.
Based on the above (corrected) plans the CC profile has an area of 10931.5 sq. mm. For a front baffle width of 155 mm that leads to a CC volume of 1.69 liters.
As posted by Dave in the above thread the way to reach the recommended 2.2 liters is to extend the CC by moving backwards the top part of the CC:
Based on my calculations if the back of the CC (part 6 in the drawings) is slided backwards for aprox 50 mm the total volume of the CC becomes 2.18 liters.
Also, as noted in the thread above, the addition of the suprabaffle -- and the consequent cutting of a profile in the front baffle -- adds additional extra volume to the CC. Obviously, the exact added volume depends on the type of profile cut in the front baffle. E.g. for a rounded hole with a diam of 112 mm (as in the PDF drawing to hold the driver) the added volume is 0.166 liters.
4) Corrections to the building plans.
Now, this is the trickiest part. The corrections I've made to those plans are only based on my current understanding and I would highly appreciate if someone more knowledgeable (Dave ? Ron ?) could verify that this is OK.
- Corrections to the length of the internal deflectors (better name?) i.e. part 4 and 7 in the building plans. My assumption is that the horn throat width is to be (cuasi) constant at the horn inflections at the bottom of the speaker (part 4) and top of the speaker (part 7). IOW the distance to the different boundaries at those inflections should be cuasi-constant / increase smoothly -- as drawn at page 5 in the PDF.
If this is the case part 4 and part 7 have to be lengthened as 793 mm and 856 mm, respectively:
- Correction to the back of the speaker (part 12 in plans). The length should be increased to 522 mm. The correction is mostly to respect the horn mouth curvature in the plans (center and radius) and the 10 degrees horn expansion angle given for that part.
- Corrections to the CC external dimensions on page 4 of the PDF. Some dimensions there are off (by some 4-5 mm).
Again, I would be greatful if someone could ack that my assumptions wrt horn inflection and expansion rates are correct.
Best regards,
Florian |
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| planet10 |
Florian,
I haven't had a chance to go over you post, but you need to resave those images as gifs (i'll help if needed) -- the jpg noise really kills the clarity of the images.
These look like they will be helpful as i rework the plans.
dave |
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| FlorianO |
Sure.
Here is the correction for page 3 |
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| FlorianO |
| This is the correction for page 4 |
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| planet10 |
Much clearer... thanx. Now that i have Aiko out of the queue (excuse the OT picture), A126 is the next horn plans for me to tackle between client jobs.
dave |
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| Scottmoose |
| Now that will be a boon. A good set of plans for the A126 is what the world needs. Oh yes. |
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| FlorianO |
Well, let's get back some life into this thread. It took me quite some time to get all the stuff together (Dave's drivers got stuck in the customs, the birch ply took extra to deliver, etc).
First, some updates:
- Based on Ron's feedback about the shape of the CC now I've revised my plans again (see this thread: http://www.diyaudio.com/forums/show...&threadid=99769)
Unlike Dave's mod, in order to get the required CC volume the CC was expanded by "pushing" at the same rate (i.e. 18 mm, or "one wall thickness") both the top side of the CC and the top sloped part.
The new CC shape and its dimensions (in mm) are detailed in the attached pic
(As above, updated high res pics of the plans + build are at http://picasaweb.google.com/florian...uildingPictures)
Suprisingly enough (or maybe not...) now the A126 CC resembles the CC in the A166 (yes, that was a coincidence, or -- as I like to think -- interpreting correctly Ron's design guidlines).
In the pic one can also notice the original (as per building plans), undersized CC.
Cheers,
Florian |
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| FlorianO |
Here is starting building the modifiled CC.
As you can see from the attached pic, newbies can cheat by both using dowels and mixing glue with sawdust to fill in those annoying 0.5 -- 1mm gaps here and there :)
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| FlorianO |
| building up the CC... |
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| FlorianO |
and the final modified CC, with a 2.1 liters volume.
Again, it now reselbmes the one in the A166 drawing
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| FlorianO |
another view of the modified CC...
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| FlorianO |
| And the whole side (a bit out of focus, crappy camera, sorry for that). |
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| serenechaos |
Beautiful!
Thanks for recording this for all of us!!
Let us know how they sound, and I'll probably build a pair too, (as I'm listening to my 166s...) |
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| FlorianO |
As per Rons advice, here is the lining of the CC:
A layer of felt (actually in my case was some fiber cloth I had around) mounted on some balsa |
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| FlorianO |
| ... then line the back of the CC with it, rougly to the point the back wave would hit the CC walls (well, very roughly :)) |
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| FlorianO |
| I'm not so sure about this part -- Ron, Dave, pls comment on this -- but I would line the horn folds with same cloth. Namely like this: |
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| FlorianO |
.... and like this.
Again, if others had any experiences with lining the folds (both good and bad) please share. Ideally before I clamp my sides, thank you :)) |
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| bobmar |
| You could try this to make the turns..... I used an epoxy mortar (1 part epoxy: 1 part sand mix) , followed by body putty to smooth out the surface. The epoxy mortar allows the application of lifts up to an inch and one half , but as it begins to set up, it becomes difficult to smooth as seen in the first photo. If you don't need big lifts, less sand makes smoother applications. The body putty (polyester resin for auto repair) smooths it over and allows adjustments in the dimensions. It would be good to make a template of the turn to place in the open end. Much easier than using a rasp. later on.....Also, if you need to use a rasp or sand paper, there is a certain moment , in the curing, where the removal of material is relatively easy to manage. |
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| bobmar |
| Here is the second photo |
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| FlorianO |
Thanks for sharing....
Still, I'm not so sure about treatment of the horn folds...IIRC ron's attitude towards folds treatment was not so favorable.
Yet still, it may very well be that rounding the corners with some sort of mortar is beneficial.
The only question is of doing that via lining with cloth or rounding it up with mortar. Or both ?
Ron ? Dave ?
Thanks again for posting the pics. Highly appreciated. |
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| ronc |
Sorry, been at the beach in NC. No puter, no phones just me and my lady and the sand and ocean.
I use a stick back felt on the turns. Use to be avaliable at wally world. A full radi would work well, but i am just too lazy for that.
ron |
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| FlorianO |
ron,
Thanks for contributing.
Wrt the radi, I was thinking along the same lines -- round the corners at the folds with either "plastic tree" (as they call it here, not so sure how you call it -- a paste that simply cures as "wood") or putty reisin.
The epoxy mortar (or white cement as an alternative ?) is heavier and should add to the weight on the bottom folds it can make the top fold heavier. And yes, laziness and unpatiences (I really want to glue these together and do some listening...).
Florian
P.S. Almost gelos on you for that NC trip. Me + better half had lunch together, just the two of us (by accident ...) and realized we haven't done this for more than a year... |
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| FlorianO |
Well, I gave in to laziness and used only felt.
For the CC and fold at the top of the speaker like this |
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| FlorianO |
..and at the bottom fold.
You can also note the speaker terminals mounted there too.
I used a single pair of CAT 5 cable down from the CC. Length is slightly less than 1m.
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| FlorianO |
Preparing for gluing up. I used quite a few dowels (20 pieces per side to be exact) for added rigidity
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| FlorianO |
One side is finished (except painting / waxing -- that's my wife's job) and second is now curing.
Of course I couldn't wait for the second one to cure to plug in one speaker and so far .... WOW ! |
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| chrisb |
nice work - I wish I had the patience for dowels - the air powered brad nailer is just too convenient.
My attention span isn't what it used to be; are you planning on supra-baffles? For my taste, in concert with Ron's deflectors, they take this design "to another level" and squeeze possibly "the last drop" of performance from the FE126e
sorry, couldn't think of any more cliches for the moment |
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| jleaman |
| May i ask what type of plywood that is ? |
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| vinylkid58 |
| quote: | | sorry, couldn't think of any more cliches for the moment |
Chris, just pick up an old copy of Stereopile, you'll have an endless supply.:D
Jeff |
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| chrisb |
| quote: | Originally posted by jleaman
May i ask what type of plywood that is ? |
over here we'd call it "baltic birch" |
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| chrisb |
| quote: | Originally posted by vinylkid58
Chris, just pick up an old copy of Stereopile, you'll have an endless supply.:D
Jeff |
or just visit our local dealer on Friday afternoon - every time I do, my headache lasts for hours, and it's not the overdose of caffeine |
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| FlorianO |
| quote: |
over here we'd call it "baltic birch" |
Over here we call it fs"#!%!ing expensive birch ply :)
Joke aside it was 18mm birch ply, made in Findland, so I guess you can call it baltic too :).
Costed around 180 USD per 1200 cm x 2400 cm sheet (yes, 180 USD / sheet!). And you have to buy them whole sheets, even if needed only one and a half (roughly).
Anyway. Back to the program.
Now both sides are cured, installed in my reference system, and gave them a serious listening and a first round of tweaks.
System:
CD player: Cayin CDT-17A heavily modded (tube buffer output bypass, upgraded O.As, improved power supply)
Pre-amp: Supratek Chardonnay
Power Amps:
EAR 890 (70 A Class A from 4 x KT90 pentodes per channel);
Audiodigit/Autoconstruire Class T 100 HCL digital amp ( TAA4100A Tripath chip) driven by 12 V 7Ah battery
Speakers: Gallo Reference 3A
Cables: Low level: Silver Siren; High Level: Xindak FS-1
Dedicated listening room rectangular 640x480x205cm (that's aprox 21 x 16 x 7 ft) in short wall setup. Damped back and side walls.
Attach is a picture of the setup. The panel was removed from the right corner to allow corner loading. As can be noted from the window positioning, this is in a cellar with side and back walls made of concrete.
Also on the floor one can note a mini OB I used for addiional break-in of the drivers I received from Dave and makeshift deflectors out of cardboard :) |
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| FlorianO |
So, how do the A126 compare with the Gallo Reference 3A (one of the best speakers I've heard, in my unbiased and very objective oppinion :)) ?
One a more serious note, I think the Gallos are very good -- especially that silver diaphragm tweeter with 300 degrees radiation. Makes jaw dropping wide and deep images, pinpoint accuracy; They are really, really fast. OTOH their drawbacks are 1) They do need to play loud and 2) The bass doesn't go very deep (60 ish) but what's there is very good -- accurate and fast.
So, how do the A126 fare against it ?
To make a long post very short: The A126 are nothing short of amazing, all things considered !!
The nitty-gritty details:
First, I tried to corner load the A126. Placed them on the room diagonals (well, roughly) at around 30 cm (1 ft) from the corner. Tried both no deflector and makeshift cardboard deflector (as the right corner in the pic above).
The results were frightening: The midrange was to die for. The treble is pretty good, but not much happening in the last octave (I'll get back to this). The only real problem was the bass: While more than aplenty -- "Output at 40 Hz (sine wave) ? Yesssir !!" -- it was booming.
In this setup the bass was simply too much. "Quick" bass notes got the transients mushed together. Large symphonic pieces (Mahler 5th symphony, "Trauermarsch") and dynamic piano solos (Beethoven pianosonata Nr 21) got (too) bass loud and muddied. Quite annoying.
Then I tried to move them a bit in the room, and even stuffed a pillow in the horn mouth :). It helped, but not by much.
Eventually I put the corner panels back on, moved the horns inside the room about 1m and removed the stuffing from the horn mouth.
The bass settled down and boom is now non-existing (well, almost) . What I get now is cleaner, deep bass notes. While sometimes I feel that the bass is "lazy", I wouldn't call it either soft nor squishy. It just takes its time to catch up :)
So, while it might be that I am unused to the BLH bass, it might very well be that some roommodes get excited due to corner loading and makes the bass boom.
Again, midrange is excelent, with female voices (Diana Krall) being just in front of me. Ella is to die for.
Sounstange, imaging: Good. Very good. While not on par with the Gallos (that are champs in this area) the A126 really does hold its own.
Treble: While good, it does feel that this is something the 126s could use a bit of help. A supertweeter helping with the last octave should add both air & sparkle and maybr the last drop of detail / image precision.
As such smth I could very well contemplate is (eventually) getting a pair of T90A supertweeters, X0 them at 10 Khz first, maybe L-pad them, and drive them in parallel with the A126. What do you think ?
All in all, the A126 is truely an amazing speaker. In some respects (midrange presence) on par with my Gallos, maybe even better :hot:
The only reason I was maybe a bit harsh above is simply because the monster slaying potential: Getting this close to a speaker costing 10 times as much should simply be outlawed....
Once again, many, many thanks to Ron, Dave, Chris and all that contributed with their advice and input. Highly appreciated. |
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| planet10 |
| quote: | Originally posted by FlorianO
The bass settled down and boom is now non-existing (well, almost) . What I get now is cleaner, deep bass notes. While sometimes I feel that the bass is "lazy", I wouldn't call it either soft nor squishy. It just takes its time to catch up :) |
How many hrs did you get on them in the little baffles?
One of the compromises of a BLH is that the stuff coming out of the horn mouth is delayed by a few wavelengths....
You will also likely find that the distance from the back wall can be used to tune the bass ... and not just back & forward but finding the sweetspot
dave |
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| ronc |
A proper deflector will help with any boom by re-directing the wave front. The cement walls are a natural for too much bass.
I dont know the Gallo series? I assume its a multi way?
ron |
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| ronc |
OK, i did a small study on the operating principal of the Gallo 3.
Sounstange, imaging: Good. Very good. While not on par with the Gallos (that are champs in this area) the
I assume ( i hate that) its a basic 2 way with a more or less sealed enclosure (whatever S2 technology is?). This would give a tight bass line but be limited in LF response.
They mention a tweeter but both upper drivers appear to be the same? Now the ingenious part! If both upper HF drivers are the same you might expect comb effect. But with the narrow curved face the wave launch at a higher frequency is focused at a point away from the box. The point ,being further away, from the baffle would give the combined in-phase signal a larger efective beam spread (hence the 300 degree thing).
Just look at it as a focused collimation with two drivers(actually the baffle launch shape) focused at a point away from the speaker. The actual physical point would be the center of the radius of the baffle and be angled at the line mid tangent point to the center. The end result is like a focused line array with the baffle launch being the focus element.
I believe i am correct in my theory, but i may be wrong .
ron |
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| FlorianO |
| quote: | Originally posted by planet10
[B]
How many hrs did you get on them in the little baffles?
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About 40 hours, maybe a bit over.
| quote: |
One of the compromises of a BLH is that the stuff coming out of the horn mouth is delayed by a few wavelengths....
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That's what I intuitively understood and tried to tidy up the bass by moving the speaker into the room. Confortable to know I'm on the right track.... |
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| FlorianO |
| quote: | Originally posted by ronc
[B]OK, i did a small study on the operating principal of the Gallo 3.
I assume ( i hate that) its a basic 2 way with a more or less sealed enclosure (whatever S2 technology is?). This would give a tight bass line but be limited in LF response.
They mention a tweeter but both upper drivers appear to be the same?
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Ron,
While I have to admit I didn't exactly follow your analysis, in my understanding the Gallos are a 3-way. Well, sort of...
On the LF side of things they have series crossover at 150 Hz to a sealed, double coil, side firing woofer.
Above that they have an MTM arrangement with twin 4-inch hyperbolic carbon-fiber mids that are "mechanically" rolled off at 3 kHz (not so sure how that works. Apparently that is equiv with a first order....).
Above 3 kHz is the cylindrical tweeter (or CDT -- Cylindrical Diaphragm Tweeter as Gallo calls it), a silver-clad Kynar (some sort of plastic ?!?) foil diaphragm. That tweeter is the true star of the Gallo line. And it sure works: Wide/deep soundstage, pinpoint image accuracy, you name it. The drawback is -- as very correctly identified by a reviewer on positive feedback -- it really must be kept away from room boundaries. It took me almost a year of tweaking the speaker position, my listening position and heavily damp my listening room to get them "cleaned up". But boy, it truely does fireworks :D
Anyway, back to the A126: I had them playing at my daughter's party today in my living room and they did sweet music. I love them more and more. Of course, some more serious listening is still to come. Maybe after the drivers break-in more, add the SB, build a proper deflector and maybe add a supertweeter.
I can definitively see myself growing into the A126, and forgive them their small shortcomings -- like the fact that they seem to bust at the seams when faced with large (and I do mean LARGE) scale music (say symphonic works like Mahler 5th, Tchaikovsky and the like). OTOH I am not so sure _if_ a single driver setup (or variant thereof) can handle that without finching. If yes, I would be more than curious which...
IOW I can definitively live with the A126 ... Until I'll get that itch again, that is :devilr: |
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| ronc |
Now i understand the mechanics,thanks. The baffle action still holds true as i stated. Its the ribbon tweet thing that i didnt get.
Any new innovative approach i am interested in for future development.
ron |
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| FlorianO |
| quote: | Originally posted by ronc
Any new innovative approach i am interested in for future development.
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Ron, have some mercy.... I've just completed that build, and wife was patiently waiting for that to be completed in order "to have a serious talk".
So, what do you have in mind :) ? |
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| FlorianO |
Ron,
Back to the A126 : Any oppinion about adding a supertweeter ? |
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| ronc |
If it was me i would just add the FT17 in the supra baffle and add an lpad. I mean why add a tweeter that would double the cost of the project. XO around 10K where the 126 starts rolling off.
Even at my age and loss of HF hearing i can truly hear the difference with a ribbon tweet rolled in at 10Khz with the 208 sigma.
You are use to hearing quality HF, i think the 126 wont deliver what you are use to hearing. TC (RIP) and i exchanged several emails about this and i go along with him.
The only problem i see is the phase so with a first order XO to the tweet at 10 Khz would require the tweet be around .33 "(8.5mm) extened( closer to the listener) from the sound production plane (VC) of the 126/vrs the production plane of the tweet. This would compensate for time alingment.
Add the deflectors as this will control the LF wavefront and re-direct the wave forward and reduce booming. The cement walls that you have reflect a much higher amount of energy at all frequencies.
As an added note , i tend to look at a FR BLH with a wizzer as a 3 way system, not a FR system. It has all the phase problems of any 3 way system, but sometimes a bit worse. At least you can correct a bit with a seperate tweet.
ron |
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| ronc |
Added notes.
If no supra baffle was used a mini truncated pyramid baffle for the F17 in a tiny sealed enclosure might be the way to go. Mount it on the sides or top for a different high tech look and performance. On the top it could be slid back and forth to adjust with white/pink noise to achieve time alingment. Just find out where you want it and glue it down. If mounted on the top or sides i would lift the assy off the surface by around .66" (1/2 wavelength @ 10Khz) to allow for rearward diffraction.
ron |
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| FlorianO |
| quote: | Originally posted by ronc
[B]If it was me i would just add the FT17 in the supra baffle and add an lpad. I mean why add a tweeter that would double the cost of the project. XO around 10K where the 126 starts rolling off.
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Makes perfect sense. I will experiment with the SB asap. Offsetting the tweet could be done by adjusting the thickness off the baffle and/or mounting it receded.
Many thanks (yet again...)
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| gnat_leader |
Hi Ron,
Well I'm wondering if I'm a bit hosed here. Myself and two friends just finished cutting all the wood for 3 pairs of A126 speakers with the side firing (L+R) horn mouth as apposed to rear firing. We used the plans from the Frugal-Horn page here... http://homepage.mac.com/tlinespeake...plans260207.pdf
Now I see a completely different CC in this thread and it worries me that we did not cut for the latest design.
So far we have put one speaker together and listened to it.
Do you think there is any way we can modify the remaining pieces to adopt the newer plan with the larger CC? In any case, what is the expected sonic difference between the newer/larger CC and the older one we built? |
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| FlorianO |
If I understood correctly the "problem" with smaller/larger CC sizes is at which point in frequency the horn loading starts i.e. the crossover point of the CC as a low pass filter as it were.
As I posted in the other A126 threads (linked in the first post) the computed CC volume for the drawing in the PDF stands at 1.69 liters. Apparently the recommended volume for the 126 is 2.2 liters (not 100% sure why...). The drawings used here simply attempt to correct that to a closer 2.1 liters.
Also, remember that the drawings in this thread are my own and were not "officially endorsed" so to say.
Now, how to model the CC lowpass as a function as a volume is well beyond me, even less so the LF "boost" by the horn itself. The only rough figure I remember seeing somewhere was that horn loading starts around 200 Hz for the 2.2 liter CC. To be very honest I would very much love to see such a curve (or guidlines wrt to that), not least to be in the know on how to dimension the SB....
For what is worth,
Florian
P.S. Just for the fun of it: Build a pair according to the PDF, build the 2nd according to my drawing and do a comparison. And then build the third pair in between :). And post the results here, of course. |
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| ronc |
Add the 1.7" T SB. That will increase the CC to an acceptable horn roll off of around 260 Hz. The dimensions of the SB ,in a retangular shape will be 11.7"/side.
ron |
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| ronc |
To be very honest I would very much love to see such a curve (or guidlines wrt to that), not least to be in the know on how to dimension the SB....
Ok the horn roll off action is a slope, the roll in of the baffle action is nothing more than a shape that will support a spherical wave of a given size. If the launch area needs to support a given dia. then
(((lamda/pi) x .707)/2) is the minimum radius.
pi x R^2= area (for a different shape, but the wave will not form correctly from a shape with a greater aspect ratio than around 1:1.414)
The effective slope of the horn roll off is calculated,The intersection of the roll in slope of the baffle is calculated. They have to meet at an acceptable point of around -3db from the combined overlayed slopes.
All this would not be necessary if we could adjust to wider speakers like the old Lowther designs. In effect all the SB is ,is an OB that supports a given wavelength. So you can see the ratio of the CC volume to the size of the SB relationship. In effect you could use an SB on any cab, its just calculating in the roll off , the dip in the FR and blending in the wave support of the baffle size/shape to make a smooth transistion from one action to another. Its nothing more than a mechanical BSC.
ron |
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| gnat_leader |
| I don't understand what a T SB is? |
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| gnat_leader |
| Nevermind. I figured it out. I'm a little slow ;-) thanks! Will post pics when finished building. |
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| ronc |
T=thickness.
Ron
Sorry i use tems and abreviations that are common in my field.
ron |
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| gnat_leader |
Well we finished one and auditioned it in mono. It's pretty remarkable how low this tiny driver can go in this cabinet. One thing though. When listening to Chris Isaak at anything above low volume levels, it's apparent there is an over-abundance of lower mids... to the point where it sounds like some kind of resonance (which is quite distracting). I am very familiar with Chris Isaak on other speakers and so I know it's not just a "bad" recording. The only deviation we made from the design was putting a small piece of Deflex on the back of the CC, *but* keeping the deflex 2 inches away from the throat opening.
I figured the deflex would be better than the styrofoam for killing bad reflections back into the cone. The other thing is we have not yet created the baffle-step compensation baffle. The wood we used was a quality 8 ply (birch or fir, I'm not sure) with no voids.
So what are the thoughts on why this is happening? Could it be the new driver which is not broken in yet? Is there any way to "tune" this problem out, say with stuffing the CC?
thanks much! |
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| FlorianO |
- Can you narrow that down with e.g. tone sweeps, warbles ?
- Positioning ?
I had a similar problem with the driver not being perfectly air-tight in the mounting hole. It was barely noticeable (less than 1 mm) but had very audible effects. |
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| ronc |
to the point where it sounds like some kind of resonance (which is quite distracting
Are you sure that the panels are glued properly? Never heard this one before?
I would remove the deflex first off, if you desire more rear CC damping Then a circular disk of styro around 3/4 to 1" thick on the rear of the driver will work.
BTW, as mentioned above, this is a pressure vessel with a long expanding vent, any leak in the pressure in the vessel ,not designed for, will have an effect on the balance of the system performance. I will not establish torque requirements for sealing (LOL).
ron |
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| gnat_leader |
| floriano, I think you are using a larger CC than I am, at least until I add the larger square baffle. So maybe doing this (increasing the CC) solve this lower-mid resonance problem? |
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| FlorianO |
To be very honest, I don't know but I don't think CC volume is relevant here. As Ron said, mine surely doesn't sound that way.
My best guess what Ron just suggested: Check and Double-check that everything is air tight. I was quite paranoid about that.
Florian
P.S. Are the side panels glued in place or are you listening with clamps only ? |
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| ronc |
I always run a thick bead of silicone around the flange/baffle interface as this is where the majority of leaks occur. All of my designs are based on a pressure and wave control, any change in pressure(not designed in) will affect the performance.
ron |
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| gnat_leader |
Thanks Ron. I seriously doubt there are any leaks of any kind. We used 100% polyurethane glue (aka Gorilla glue) for all the panels... which expands when drying and would have filled any cracks. And all the pieces fit tightly anyway - we did a good job with cutting all the pieces. Also knuckle rap tests find all the panels to be quite stiff/inert. It's not coming from the panels.
One think I just thought was it could be the room which was a live/reflective room. We'll have to hear it in another room. |
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| gnat_leader |
| Everything is glued. In fact we used way too much glue as it has oozed out most of the seams... will have to razor knife off the dried excess. No worries though since we will likely be applying veneer on top anyway. |
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| gnat_leader |
| I know with the HornShoppe horns Ed does use a light amount of stuffing in the CC to tune them. What effect would this have on the A126? In any event I may experiment with trying it. |
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| planet10 |
| quote: | Originally posted by FlorianO
To be very honest, I don't know but I don't think CC volume is relevant here. As Ron said, mine surely doesn't sound that way. |
When Chris & i did the 1st rev of the A126 with the smaller CC we had a midrange problem too -- our description was a bit different (a closed in, hands cupped kind of colouration on vocals), but with the inaccuarcy of using words to descibe what something sounds like, we could be talking about the same thing. Ron took what we had said and went back and deiscovered analytically what we were trying to describe, leading to the largwe CC and the supraBaffle to compensate for the change in low-pass the larger CC brought about.
Deflex eats volume, so that should go, a little damping with increase the apparent volume a little bit (why Ed needs to add some to the Horn). A temporary spacer could be added to the front to explicitly experiment with larger CC vol, and then have extra volume built into the supra-baffle.
Also worthwhile cutting out a cardboard supraBaffle just to see how that affects things.
dave |
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| bobmar |
My 126A did have a resonance problem which was solved by glueing 1/4 inch hardi- backer to the exterior sides of the box. I did not use great plywood and that must be the reason. I clamped wood and other things at various times on the sides which made a differance, but the 1/4" board made a dramatic differance, maybe just because it was clue applied.
As far as inlarging the CC, I cut the baffle board area out where the speaker was mounted so that the opening is square and flush with the interior sides. I added a SB that was two layers on one and three layers on the other. The carving out of SB interior to flow into the box interior gives a bit more volume. I did not measure the volume, but the three layer baffle seems to sound more full spectrum.
Bob |
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| FlorianO |
Bob,
I was thinking the same way: Enlarging the driver cut-out in the front baffle all the way to the the sides (practically means cutting the top 155mm square of the front baffle) and mounting the SB on top. The reason was to avoid creating a 54 mm (2.1'') round "tube" out of the 3xT circular cut-outs for the driver (1xT in front baffle, 2xT for the SB). But that will not allow removing the SB afterwards if I in the end I will still prefer it without the full monty :cool:
All that if I will mount the SB that way, that is. Haven't gave too much though to alternative ways of mounting the SB -- like building it _around_ the front baffle and sides or smth.
gnat_leader,
I assumed that when you said "resonances" you did meant just that. Colorations and closed-in sounds are a different matter. I for one just took Dave and Chris extensive experiences and advice and dimensioned mine accordingly.
For me a very telling experiment was to mount the driver on a mini OB and give it a listen (during driver break in). _That_ made me appreciate how good A126 truely is :hot:. |
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| bobmar |
Florian
Seems to me , your correction of the volume of the CC was the best. It kept the design and allowed the increase in size. My 126A does have a sort of boxy sound to them[a sort of echo chamber] I would have liked to compare the before and after[without the SB and with the SB], but having cut out the baffle area, I could not. My 166A does not yet have a SB and it does not have that sound, but there is a bit more of a story with them. I am using a 166es-r and I diminished the size of the CC by lining the side walls with rug material. there is a point where the sound begins to lose that auditoriom quality and get more appropriate.I can easily change it and have tried more and less amounts. This can be done because the CC volume requirements for the 166es-r is less as I understand. So, I did one of those"I wonder what would happen if I did this? and it seems to have worked just fine. I should pull the rug liners just to see if there is any comparison of the two sets of speakers.
Bob |
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| FlorianO |
Bob,
Thanks for the kind words. Again, that CC mod was a matter of following Dave, Chris and Ron's advice (and some luck, I guess :))
Today I've installed an SB (carboard, temporary) and I have to say I was not _that_ impressed after a half-serious listen. Comparative listening with or without is a bit difficult -- will try to do it by bending the SB and then unbending that carboard. On a second thought maybe I should be a bit more selective and find material with more energy around the 260 Hz and look for differences there (since they should be rather subtle)
gnat_leader
While listening for the SB today I noticed a really annoying boom on mid bass, especially on male voices. Worryingly similar to your report on Chris Isaak material.
After a closer analyisis (well, that means running the material through a RTA ;)) it turned out that it was around 100Hz. After some thought I remember noticing that on some classical material that I know has a peak there too, so it was not a coincidence.
Still, upon checking the room modes for my dedicated listening room (rectangular, no openings) it I do have some room modes concentrated there (80Hz, 107Hz,134 Hz longitudinal, 89Hz and 134 Hz lateral and 84 Hz height). As such it would be a fair explanation to blame that on the room.
Anyway, I still have to listen to it "properly" in another room to rule out cabinet/horn resonances completely (my uber-cheapo DVD player + digital amp in my livingroom doesn't really qualify :whazzat: )
Hope this helps,
Florian
P.S. As I mentioned above in this very thread -- and confirmed more then plenty today -- placing the horn firmly in the corner bloated the bass to the point of rendering it unlistenable. But that is only due to my concrete walls and is definitvely not speaker related (by moving it inside the room I can tune the bass quite a bit). |
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| gnat_leader |
Dave,
thanks much for your reply. I do believe we are talking about the same problem/issue. Question: if we add a spacer or supra-baffle of the specified thickness , what diameter should we increase the existing driver hole to? ie, to let the back-wave from the driver "breath"? Right now we have it just large enough to fit the driver and scalloped at 45 degrees on the rear of the baffle. |
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| planet10 |
Make the hole as big as you can get away with. A rechangolar cutout (with 45s) is probably better then round.
dave |
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| chrisb |
| quote: | Originally posted by gnat_leader
Dave,
thanks much for your reply. I do believe we are talking about the same problem/issue. Question: if we add a spacer or supra-baffle of the specified thickness , what diameter should we increase the existing driver hole to? ie, to let the back-wave from the driver "breath"? Right now we have it just large enough to fit the driver and scalloped at 45 degrees on the rear of the baffle. |
When using drivers with the limited clearance from large magnets such at least the entire FEnn6 series of Fostex, I'd agree that it's very important to allow some "breathing" room on the rear side of the baffles, and particularly so with double layers as a separate supra-baffle will create.
One solution is to flush mount the driver on the standard width enclosure panel, and bevel the driver opening on the front side of the supra baffle. Depending on the thickness of material for the SB, you can end up with a shallow waveguide, such as seen below.
These were sized for a friction fit, to allow the quick demonstration of "with and without". (hint - they seldom play for long without them)
Aluminum angle brackets and closed cell weather strip tape could make for a fairly simple, and well sealed installation - just don't use the baffle as a carrying handle.
If the panel to which the driver is presently mounted is not removable, it won't be particularly troublesome to enlarge the hole, but it obviously be a nightmare to chamfer the rear side. In that case, I'd be inclined to cut a square opening, almost flush to the perimeter of the 4 sides of the CC.
For those concerned about the extra volume that such spacing of the driver's mounting plane will create, this'll make it much easier to add solid blocking to the rear or side walls of the CC. |
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| gnat_leader |
Chris,
Thanks for the feedback, but I'm not sure you've been following what we've been talking about. One of the reasons for adding the supra-baffle is to increase the CC volume provided by moving the driver forward the thickness of the baffle. If your version of baffle is added then how would we increase the CC volume? |
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| chrisb |
| quote: | Originally posted by gnat_leader
Chris,
Thanks for the feedback, but I'm not sure you've been following what we've been talking about. One of the reasons for adding the supra-baffle is to increase the CC volume provided by moving the driver forward the thickness of the baffle. If your version of baffle is added then how would we increase the CC volume? |
Sorry, it wasn't clear from the above posting that the CC in this pair had already been enlarged after our first audition. In addition to a cosmetic modification to the outside shape, there was some major surgery involved in routing off the sides, and moving the rear wall back several inches. ( somewhere Dave has pictures)
You'll note in the posted picture additional plywood "cheeks" that enclose the revised CC, as well as layer of 1" MDF on the outside of horn mouth, for resonance damping. |
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| planet10 |
| quote: | Originally posted by chrisb
( somewhere Dave has pictures) |
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| planet10 |
We had already extended the back with a false chamber to hide the existance of the camel hump . So chris just opened everything out giving us a CC of some 4 litres or so, Then we just started filling it up bit-by-bit.
dave |
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| gnat_leader |
So what IS the ideal CC size then? Is it 2.2 liters as mentioned in the first post of this thread? ...
"As posted by Dave in the above thread the way to reach the recommended 2.2 liters is to extend the CC by moving backwards the top part of the CC: "
And if so, how can I calculate the dimentions? Man, if I would have known how incomplete the plans pulled off the Frugel-horn site were, I'm not sure I would have started this project. Sorry to bicht, I know it's allot of work and you guys are not getting paid for this.... |
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| planet10 |
| quote: | Originally posted by gnat_leader
Man, if I would have known how incomplete the plans pulled off the Frugel-horn site were, I'm not sure I would have started this project. Sorry to bicht, I know it's allot of work and you guys are not getting paid for this.... |
There is a comment to that affect "Note: these are plan documents assembled from various bits & pieces that were gathered from various places on the web. I will be working with Ron to get prettier, more consistent (& up-to-date in some cases) drawings"
dave |
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| ronc |
Another satisfied customer?
Dave let me crank up my home CAD and see if i cant get some DWGs to replace the old ones. If the old revs are incorrect they shouldnt be posted.
Problem is i am involved with at least 5 projects at work and another 5 involving audio and auto and GEO greenhouses. So if i post a horn design with a large transparent dome cover with controlled air flow and ground insulation and articulated steering then i have my projects crossed.
Added to all this is a general poor health and being a semi temporary resident at the local hospital and the sum total of load ,all i can do is try.
ron
(Forums are an easy place to gripe) |
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| gnat_leader |
Ron,
Don't worry about it man. I think I got it figured out. I'm thankful to you for your designs... and based on my initial listening session, I'm salivating at what this will sound like if I can get the CC right and lose that "hand clasped reverberation" problem.
cheers, -Brad- |
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| ronc |
Sounds good. I am sorry if i did not see this in the original plans ,but all i can offer is the fact that the math worked out. I am not truly an audiophile, but more of a number cruncher and general problem solver, it took Dave and Chris to bring my errors to light.
ron |
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| gnat_leader |
It looks like we need to add .51 liters (31 cubic inches) to the CC.
If we cut out a square 6"x6"x.75" piece of front baffle and add another on top, we get close (27 cubic inches). If we can cut a rectangle 6"w x 7"L (down) without moving into the horn throat area we will get 31 cubic inches. |
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| FlorianO |
gnat_leader,
I calculated the CC volume by computing the CC cross-section area (as in the PDF) using old fashion planar geometry. To get the CC volume just multiply it with the baffle width. Nothing complicated.
As posted by someone else on a related thread (see my first post) another quick-and-dirty way to measure the CC volume is to put a plastic bag in the CC and check how much water you can pour in it.
Sorry if being too direct but I think you should have been a bit more careful in at least reading the PDF -- if not parsing the posts and reports from previous builders. IMHO this is one of the builds with quite a few reports.
Besides, Ron is already very busy in devising the plans for the Altec VOTT clone (without articulated steering) :D
Ron,
Take good care of you man. Health comes before anything else. Best wishes.
Florian |
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| gnat_leader |
| I did read the PDF along with two friends who helped with cutting the wood. We found numerous shortcomings, especially with the drawings of the side firing version we are building. As for going through the posts.... I barely have time to build these things... let alone reading through hundreds of postings trying to dig out the truth. It's frustrating, but I understand... these plans are free, and people have donated their time to create both the design and the drawings. Btw, personally I'd rather pay some small fee.. say $25 for the plans and know they will be spot-on. It's worth it to me not to waist the time. So Dave/Ron... perhaps there's potential here. You guys could make a few bucks and get duely compensated for your efforts! ;-) |
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| planet10 |
| quote: | Originally posted by gnat_leader
Btw, personally I'd rather pay some small fee.. say $25 for the plans and know they will be spot-on. It's worth it to me not to waist the time. So Dave/Ron... perhaps there's potential here. You guys could make a few bucks and get duely compensated for your efforts! ;-) |
People are making donations... a "bribe" like that can rearrange the queue.
I think you are probably the 1st person to do the side firing version.
dave |
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| gnat_leader |
| Good point. I'll ping the other two guys for kicking in some bucks for a donation... We are building 3 pairs of the side firing config. Will post pics when finished. First (trial) pair is almost together ... just raw plywood... to be nicely veneered later if we like what we hear. |
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| gnat_leader |
| Dave, what differences did you hear once you modified the 126 driver (Mod Podge on the cone)? Did the treble quantity/quality diminish at all? |
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| planet10 |
| quote: | Originally posted by gnat_leader
Dave, what differences did you hear once you modified the 126 driver (Mod Podge on the cone)? Did the treble quantity/quality diminish at all? |
The top end is much smoother, much of (but not all -- at least yet*) of the HF peakiness removed. Noise floor is reduced allowing greater downward dynamic range.
Florian has identified what we think is a remanent of these at about 6 k. Not masked by others he is finding that is stands out. Anyone suggest a starting point for a notch filter to see if that can help?
dave |
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| FlorianO |
Thanks Dave. Really appreciated.
Alternatively -- as I posted this question in the other forum -- it would be good to know if there are any full range replacements for the FE126 we can try (i.e. similar size, Fs and Qts but -- ideally -- smoother and more extended).
Thanks again,
Florian |
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| planet10 |
We are just now trying FF125 in the Frugel-Horn... specs are almost exactly the same as the FE126
dave |
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| chrisb |
| quote: | Originally posted by planet10
We are just now trying FF125 in the Frugel-Horn... specs are almost exactly the same as the FE126
dave |
thanks for the nudge - I'll have to dig out the soldering iron tonight |
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| ronc |
Is the notch at 6.5Khz a positive?(FR curve talking here)
ron
Just looked at the FR graph, angle the drivers 15 degrees off axis from the listener position. Now you need a wide dispersition tweeter rolled in at around 7.5Khz. |
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| gnat_leader |
| is that 7.5K 1st order x-o slope or what? thx, -Brad- |
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| ronc |
7.5 Khz first order. Howevr if phase correction is desired then the plane of the energy production of the tweeter will have to be closer to the listening (target point) position by .45" than the VC of the A126.
ron
(from my tech postings in the FR forum)
I really dont feel well at the moment but i wanted to post this. I really should post this in a white paper but i am not up to it at the moment.
On the subject of plane alignment of transducers at crossovers.
1. This is an evaluation of first order crossovers at a 90 deg phase change.
2. This is an evaluation of physical plane (vertical plane placement) of the energy producing points of two transducers.
3. This has impact on the order of wave points ( ie: points on a sine wave) and the time /distance of the arrival of the wave points to a given greater position.
If you look the given general concensus is that adding a first order crossover will give a 90 degree phase change. This means that the secondary transducer will see the signal at a later time than the first. The time that the second transducer will see the signal is based upon the V of the signal transfer circuit plus the added phase differential. I am not going into the " speed of electronic conductance" as this means very little in audio.
Given that at a 90 deg. phase difference that the signal will become effective the distance is:
dis=(V/F)/4.
where: dis= distance
V= velocity of the medium
F=frequency in Hertz
This is fairly simple as at 1/4 wavelength it is a 90 degree phase change. So the time/distance of the phase change is dependant on the velocity of the medium ( air) and the frequency.
Conclusion: Proper placement of the transducers in respect to the listener position should be taken into account for the difference for the phase point of the added delay of first order crossovers. Physical alignments of the planes of energy production should be adjusted for the phase difference.
ron
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| ronc |
Needless to say that the signal between the two transducers are out of phase till the XO point then they are in alingment, then as the first driver falls off in response the second picks up the signal. This makes a statement for the initial driver to be rolled off electronically and allow the slopes of the two to intersect at a given frequency and a given distance(lamda at a frequency) between the two centerlines of maximum energy.
ron
(ron gets on his soapbox) One of the greatest falts of the modern day commercial designs is time alingment IMHO. The second is baffle step comepensation. They design around very skinny tall cabs which are visually acceptabe according to SAF but in electronically inducing a correction factor the components introduce a "sound" of their own. Then they introduce a multi driver assembly ,there is no compensation of the signal arrival time. |
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| FlorianO |
| quote: | Originally posted by planet10
Florian has identified what we think is a remanent of these at about 6 k. Not masked by others he is finding that is stands out. Anyone suggest a starting point for a notch filter to see if that can help?
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Based on the freq. measurements avail here and on the measurements in the thread on Dave's FE126 mods I am targeting for a parallel notch with -3 dB at 6kHz and 7kHz and 9 dB attenuation.
Simple calculator here
Oppinions ? suggestions ?
TIA,
Florian |
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| planet10 |
I don't have much practical experience with notches, the help here says broad adjustments, and i note that the calculator gives the same results for 5 dB as for 1 dB. (i used 6,2k & 7.1 k based on Trol's graph)
A series notch filter in parallel with the driver might have greater specificity, but the calc on that site assumes you are dealing with a fundemental resonance.
Also keep in mind that the peak on the modified driver is likely not as severe as what Trols shows (my measures are problematic (has to do with the mic i used)). The impedance curves show a reduction in the primamry resonances bump.
dave |
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| FlorianO |
Dave, many thanks -- with some delay -- for the input on the notch filter. I'll dig more into it as time permits.
In the mean time I've been (too) slowly working on adding an SB to the horn. (Very) unfortunately this was a bit misguided mod, so this is kinda "how NOT to do it".
First, many apologies to Ron are in order. I should have know he must have thought about this ....
It all boils down to the misguided belief (read on several posts, some by Ron himself) that the backof the driver should be obstructed as little as possible in order not to obstruct the back wave. As such I thought that front mounting the driver on the front baffle (well, not much choice there) was less then optimal since the back wave is laterally "obstructed" for a depth equal to the thickness of the front baffle.
Consequently I thought it would be better if I would remove that obstruction by rear mounting the driver on the SB and do a cut-out in the front baffle.
I've started by cutting out the front baffle for a height just about enough to fit the whole driver frame (130 mm x 155mm cut-out i.e. the cut is for the whole width of the front baffle):
The SB consists of a stacked double layer of 18mm plywood.
The lower layer is friction mounted around the speaker (like Chris suggested above).
The lines above and below where the driver is mounted show where the cut-out in the front baffle fits -- not more then 3mm above and below the driver frame
The top layer of the SB has the driver cut-out and the edges routed at 45 degrees:
Driver rear mounted and ready to go (I added the dowels for extra bracing/fit. The front/upper layer of the SB comes flush, air-tighty with the speaker front baffle):
Everything mounted and playing:
Why it wasn't such a good idea: The speaker is much leaner, a bit too much actually. It sounds "thin". Yes, it's the bass seems "faster" but now it does sound like coming from a 4''er. In frequency terms the output around the critical 100 Hz region is reduced considerably
Not sure if the reduced horn action is due to the added CC volume (removing that 130mm x 155mm adds a volume of 0.362 liters to the CC volume, already at 2.1 liters) or the fact that what now consists the front baffle wall has a 18 mm "step". Anyway, it sure was better with driver mounted as it was before.
I've experimented very briefly with stuffing the CC with wool felt (yes Ron, I know you don't approve CC stuffing, just had to try it) but it didn't make any significant differences.
The worst part of it is that now the whole balance of the speaker is lighter and the aforementioned peak in the treble even more distinguishable.
So, any suggestions how to fix this ? My obvious next move would be to try to mount back the front baffle cut-out around the driver and glue that to the back of the SB such that to regain as much as possible of the original CC shape and volume. Any other suggestions are welcomed
Florian
P.S. The SB dimensions are exactly like Ron posted above: Squared, 30 cm. The SB itself does it job and fills in the 250Hz region nicely (didn't had a sine of exactly 260 Hz around). |
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| ronc |
With a CC volume of 2.46 liters you have drastically reduced the horn action. Which is why i quoted a 2.2 liter with the sized baffle as they worked hand in hand to balance the XO point. What you have now is a highly tuned BR with the vent firing into a horn expansion. Adding woll may just give the effect of an even larger CC. I would not be surprised that at somewhere between 180-240 Hz there is excessive cone movement.(loss of loading)
Install a wooden block that will reduce the CC volume to 2.2 liter. Or better yet several small wooden sphers at the rear of the cc at the angle point.
ron |
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| FlorianO |
| quote: | Originally posted by ronc
Install a wooden block that will reduce the CC volume to 2.2 liter. Or better yet several small wooden sphers at the rear of the cc at the angle point.
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:worship:
Will do asap. Thanks (yet again...) ron. It's amazing how such a change can do to the character. But then again, you were referring to 1 degree changes in the flare, so...here's for living in the world of exacts :cheers:
Florian
Now. Where was that wooden necklace my wife has ?!?... |
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| ronc |
I have no idea if there are Hobby Lobbys there. Its one of the places i haunt. There are all kind of craft things that can be applied to DIY audio. I still dink with the Estes mdl rockets there.
ron |
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| acarinanders |
Hi, I just have a short question regarding the CC volume.
Basically, Is the driver volume included in the total volume, or should the CC be extended with the driver volume to achieve net 2.2l?
I guess that Ron, who designed this horn is the only one, who could tell. I have attached an example with a snapshot from the mikasa spawn series, where the driver volume for FE126 is stated.
Anders |
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| ronc |
2.1 liters ,not including the volume of the driver displacement.
ron |
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| acarinanders |
Thank´s for your reply Ron, I have used your info regarding the CC as well as the existing gif-files as indata for a cad-version of this speaker.
I think I am pretty close now and i am also going to build a set in the near future.
The drawing is based on 0.72 ply, we use 18mm ply in Sweden (which is actually 17.7 mm nominal). I will make a version of this one as well, as the difference will affect the depth with a couple of mills.
Anders |
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