909-8A: 400Hz tractrix horn?

hi all,

my first post here, theophile suggested i move my
thread from lansing heritage to the altec board.

planning to use the drivers from a pair of 90's altec
A700's in a new project. hoping to draw on the
experience here to help guide the process.

have access to cnc routers and anechoic testing and
will be able to compare a series of horn flares.

i have a design/liberal arts background and can
understand the general principals but am limited in
my ability to penetrate the technical aspects of horn
building

however i have some very clever people to help
out at this end - so with your assistance i'm sure
an interesting speaker will result

cheers,

adam

Welcome to AUB, Adam.
Can you tell us a little more about what you're hoping to do? Is this for Hi-Fi? Are you just experimenting? What kind of cabinets, crossovers, etc.?

hi all,

for hifi; picked up a pair of A700's with matching
crossover and mosfet amps - have a thing for
triode amps so i thought it would be neat to use
the 515 and 909 in a 2 way for home listening.

have been reading around horns since i came
across 'gizmo' rosenberg in the nineties.

about time i got the dust flying and built a
speaker myself... can even make comparison
and measurements of different flares (should
be able to arrange both free air and anechoic
tests)

earl k at audio heritage has posted me a couple
of links to follow up - can't post a link directly yet
as i only signed on to the altec board yesterday.
he's recommending a radial horn - something that
the 'pi' speakers chap makes a good case for.

also, friend who's been in the speaker biz here
since the 70's has a good fat file of altec info -
box plans and such, will see what else is in there
and could scan any material of interest to the group.

kind regards,

adam

Temper your expectations with the number of systems that Altec used a tangerine equipped small format driver in crossed that low.

IMO&E, those drivers are best suited to XO points 1.2khz and above, YMMV.

Welcome to the Board Adam !

hi all,

thanks bowtie - i was wondering if a one inch throat could
really meet the woofer somewhere below 1k.

but how high can the 515 be crossed over and still sound ok?

not aiming for true fullrange - just whatever can be sensibly
achieved with the drivers to hand - best use rather than
ultimate system.

also, is there a plain english explanation for the operation
of phase plugs - jbl radial, altec tangerine, tannoy pepperpot?

same job - different geometry - how does it work?

warm regards,

adam

btw - had my ear up to a tannoy 15" in a canterbury enclosure
very smooth tweeter - even from an inch or two away...

hi all,

here is the link to the thread i started at audio heritage
on the same subject (before theophile recommended i
visit with the AUG); will keep both threads open with
info and pics - some pics already up at AH.

909-8A & 515-G - suggestions for horn and bass alignment please

warm regards,

adam

The simple and not-particularly-useful answer is to cut the 1" off as high as possible and the 515 as low as possible. I'll bet you already knew that!

I think you can "get away with" 800hz XO, especially on a 400hz horn, but Bowtie is right that your 1" drivers sound better 1200 up.

If you are going to go so far as to make horns, why not switch to a 288? Make the horn 1.4" capable with an adapter to 1" for now. A 288 on a 400hz horn will play down to 500 nicely.

The other thing I will say is that most round tractrix horns are like laser beams. Verrrry narrow. Yes, they image like crazy but the sweet spot is so narrow you can hardly fit two ears into it (only half joking).

If you want a tractrix, look to the Klangfilm/Siemens square tractrix for the Eurodyn as inspiration. It is a 2" horn, good to 600. One of the best small horns I have heard. It was nearly ruler flat 600-9k with a WE 594A when I measured it.

Here's a pic of the later plastic version. The older metal one is better.

Eurodyn Thomas Schick

see also ?????????????????ȡ??????ǥ????Ȳ???

You can see Eurodyn vids on you tube where a louvered diffuser is installed in front of the speaker to improve dispersion characteristics for theater use, but it is not too bad...subjectively no more directional than most exponentials.

The EH500 mentioned by Earl K in that Lansing thread is also a killer horn.

I don't know how many samples of either can be found in Kiwi Land, but these are the two small horns I would pick for models if I were looking to mill something out. These geometries work and if you could make either out of hardwood, that might get you to the top of the food chain in a hurry.

Here's a sweep of the Eurodyn horn with a WE594A (red trace). Man, that combo sounded great!

hi all,

here are a couple of altec pictures.

first is a two way hiding under the
stairs at the university acoustics
dept - hope to rescue it sometime.

the second is my friend matt at
clarry the valve tech's place.
mono stack with altec 605, vitavox
mids and a goodmans trebax for the
tops. leak monoblock for power - for
playing blues cuts etc.

clarry also has model 19's in his
front room now...

cheers,

adam

ps - is it better to link to photo
site than add images to post?

hi geekstar,

thanks for your input - will digest
and post again.

have the A700's to work with so
whatever solution will give best
results (am ok with compromise)

radial horns seem the easiest to
work with - turning a 3ft horn flare
looks like a 'major'. less material
and dispersion/reflection control too.

my friend who can negotiate
hornresp and leap quite keen to
make a series of flares and make
objective/subjective comparisons
- don't have to get it right first time...

nz has some great native timbers
if we go with that instead of ply. is
density the key? eg high pressure
laminate 1450kg/m3, keruing ply
about 800kg/m3 and aussie hoop pine
comes in at 600kg/m3.

anyhow,

cheers,

adam

It's better to link into them from a photo site like (photobucket,Flickr,) by posting the full size IMG code.This site has a auto resizer that makes them smaller.

Adam,

Check out this Sound Practices article about Altec 909s, 515-8Gs and tractrix horns.
http://home.earthlink.net/~jmarkwart...spexemplar.pdf

Jeff

hi jeff,

thanks for the link - actually, the exemplar is
my original inspiration for converting the A700's
- had wondered about getting in touch with the
designers but thought i should come and meet
with the altec fans and consult.

very pleased to make your acquaintance -
what a fantastic looking beast the exemplar is,

cheers,

a

Quote:

---

Originally Posted by adam_ecofan

hi jeff,


- had wondered about getting in touch with the
designers but thought i should come and meet
with the altec fans and consult.

---

Yeah, forget the Exemplar designers...talk to Jeff instead of those jokers. :p

JR

Those Exemplars are pretty cool. Never heard of them before tonight.

hi all,

glad there is atmosphere of bonhomie
round the forum - certainly better than
a hairsplitting contest...

news here: have to move the rig from
its warehouse lodging to a friends
double garage - turntables there though
- haven't treated them to vinyl yet so
something to look forward to,

warm regards,

a

hi all,

rig in new location - will load pictures to my picasa page
and post link; my thread at audio heritage has pictures
of rapid prototyper output from the machine at tech -
pretty good resolution objects.

also, my source for the A700's had a rummage and has
turned up 299-8A's as an alternative to the 909's....

any thoughts?

warm regards,

a

Quote:

---

Originally Posted by adam_ecofan

hi all,

<snip>

also, my source for the A700's had a rummage and has
turned up 299-8A's as an alternative to the 909's....

any thoughts?

warm regards,

a

---

Grab the 299s ( says a guy who loves the natural mid-range of the 288-8K ) .

FYI, with a change of diaphragms ( from GPA ), 299s become 288s .

>< EarlK

Quote:

---

Originally Posted by Earl K

Grab the 299s ( says a guy who loves the natural mid-range of the 288-8K ) .

FYI, with a change of diaphragms ( from GPA ), 299s become 288s .

>< EarlK

---

hi all,

thanks earl,

still coming to grips with the altec nomenclature - units in
question are 299-8A's and AT's. chap actually has 8 of them!

they've been in storage for a while and there is some
minor corrosion on the motor exterior - will grab a photo
next time i'm out his way.

cheers,

a

hi all,

altec 299 photos at the audioheritage thread,
going back out to see if there are matching
woofers and horns hidden somewhere too,

more news as it happens,

a

hi all,

went to see if there were woofers to
match the 299 stash - indeed there
are - 411-8A's; not sure how many
but hopefully enough to see a few
sets of altec speakers built - don't
hold your breath though - may take
some time to manifest results...

cheers,

a

??? 411s are 3-6 dB less efficient than 416, 515 [at least the originals], so at minimum you'll probably need two/channel if you want similar efficiency.

GM

Are you sure you saw 411-8as ( & not 421s ) ?

<> EarlK

hi all,

hi gm, hi earl:

think 411's - still new to altec
- didn't eyeball them - should
be at least 4 of them.

fellow may have other woofers - has
a big library of drivers from the last
50 years or so...

will still pursue 909/515 for now but
good to know other drivers 'to hand'
for further experiment.

thanks for following,

a

ps - gm - thanks for help with little
coral driver calc at diyaudio the other
year - had to pass on the drivers to
another enthusiast though....

hi all,

slightly off topic - there is a new p.a. about
to have it's debut in ak - horn loaded wall of
sound for reggae & dub shows.

something i'd been idly dreaming about for
a while - glad some folk have realised it.

only pics i could find are on a radio station
gig guide page (or the builders f*book) but
i'll hit the show next week and grab some
details.

old friend 'dubhead' is playing records on the
night...

cheers,

a

Lion Rockers Hi-Fi Soundsystem

hi all,

hey geekstar - what do you reckon about
dave's fastlane 'eliptrac' hybrid flare for
klipsch drivers?

New Horns

perhaps a similar strategy for the 909's?

cheers,

a

No idea how that elliptical would sound but it sure looks cool!

I like to tell myself there is a link between looks and sound, and on some level there probably is, but in my case it is mostly ex post facto rationalization! If I like it, I find a physical visual explanation and if i don't I find a geometric explanation for that too...but I'm just guessing for the most part.

I can say that the horns I mentioned above really sounded fine and some like the Eurodyn tractrix and Emilar EH-500 are well lknown for their performance. I don't doubt that there are cheap and available horns that are competitive but I can't name any beyond the few specimens I've tried.

Horns that look about the same can have a very different flavor. Gotta try them out.

There are a lot of horns, guess they call em waveguides, around these days. It might be worth buying a few hot contenders and if you like them, then laser scan and CNC them out of more exotic materials....although perhaps molded plastic isn't the worst.

hi geekstar,

still kicking tires here - my friend who can
run the sims is still busy finishing work for
his masters degree...

eurodyn's very handsome - (not sure if there
are klangfilmists here) - square format interesting.
how do they image compared with round tractrix?
do they also throw a tight image with a small
hotspot?

oval makes sense for me as it seems to present
fewer discontinuities in flare, easier to blend an
oval into a circle than a rectangle.

also, should the calc for the flare start from
the exit of the compression driver or include
the 'root' of the flare back to the phase plug?

cheers,

a

Presumably the flare begins at the phase plug, but this is not really something you have much control over.

The Klangfilm horn is considerably less beamy than the round Edgarhorns, which was my personal clash with the ultimate in beamyness.

Beyond the question of frequency response and dispersion there is the fuzzier but critical notion of sonic "presentation," which includes but is not limited to these measurable quantities. I guess I'm trying to get at something like "musicality" which there are no meters for.

The Klangfilm horn is easy and unstressed sounding, colorful, detailed...just a real joy to hear. I have heard these with the AlNiCo Klangfilm drivers and the WE 594A, both superb drivers, which surely flavors my impressions.

The round wood Edgar horn with 288s or TAD 2001s(with Edgar's adapter) struck me as very narrow, super high rez, and a little bit hot and edgy. The Edgarhorn had insane 3-D portrayal in a small sweet spot though and most of my friends really liked them...guess it is a question of taste, as always.

If you look for horn shootout from European Triode Festival 2010, JM LeCleach gave a paper which provides polar measurements on the Klangfilm and other horns, including his JMLC flare. I think the Klangfilm "won" the listening test, which like all such events was a bit thrown together but surely instructive. Google "Klangfilm ETF horn shootout"

One thing the Klangfilm horn has going for it is small size. Many of the contenders are far longer and far larger, more challenging to mill out.

I never heard the LeCleach horns but a few of my friends own or build them and they love em, e.g. Jeffrey Jackson of Experience Music (blog hifiheroin) made some short fast flare JMLCs and he is a believer. Certainly worth researching.

ETF horn link is here:

European Triode Festival - ETF 2010 Shootout


I should add that the Klangfilm horns are often used with diffusers which look like air duct vents. They call them "acoustic lenses":

See here under "documentations" Klangfilm Home!

Although this might be a beneficial addition for the intended theater application, I didn't find these horns to be objectionably beamy without the acoustic lens.

Quote:

---

Originally Posted by Geekstar

Presumably the flare begins at the phase plug, but this is not really something you have much control over.

...

Beyond the question of frequency response and dispersion there is the fuzzier but critical notion of sonic "presentation," which includes but is not limited to these measurable quantities. I guess I'm trying to get at something like "musicality" which there are no meters for.

...

The Klangfilm horn is easy and unstressed sounding, colorful, detailed...just a real joy to hear.

---

hi geekstar,

was wondering about flare from phase plug because the
transition to throat (could be) the most sensitive area for
discontinuity (if significant).

think you have it with the nebulous musicality - your plug
for the klangfilm flare is quite persuasive. i don't need in
your face precision but i do like a lively presentation -
'unstressed' is a pleasing thought. mmmm.... alnico....

do like the scale and presence from horn systems - even
from the rather compromised sounding A700's.

have a friend in east germany with an ecofan '45' - must
encourage him to seek klangfilm fans in his neck of the
woods, (closer to poland than berlin....)

....

what effect does total interior volume of the horn have?
is it less important than the growth in area of the section?

not well formed question - just something tugging at the
corners of my mind.

cheers,

a

Quote:

---

was wondering about flare from phase plug because the
transition to throat (could be) the most sensitive area for
discontinuity (if significant).

---

Certainly true...but what were you planning to do about it? You are stuck with what the factories made.

I think this is one of the reasons that I'm liking the Renkus Heinz setups....very thin driver with a short fast flare rate integral throat in the driver body connected to a throatless fast flare horn. Whole/holistic system design. Smooth expansion all the way.

Within most of the included angle of the RH horn, the diaphragm is line-of-sight. Or, it would be except for the bug screens and phase plug in the way!

Why not play around with Hornresp and simulate a few designs, play with the variables. That will give you an idea of trends.

Hornresp

The subjectivist in me, or let's say the experientialist, says the math won't predict what will sound good, but it can tell you what a given design can achieve in gross metric terms.

I'm not a horn designer...more of a junk collector and listener.:p

Quote:

---

Originally Posted by adam_ecofan

clarry also has model 19's in his front room now...

---

Lucky guy!

Quote:

---

Originally Posted by adam_ecofan

hi all,

rig in new location - will load pictures to my picasa page
and post link; my thread at audio heritage has pictures
of rapid prototyper output from the machine at tech -
pretty good resolution objects.

also, my source for the A700's had a rummage and has
turned up 299-8A's as an alternative to the 909's....

any thoughts?

warm regards,

a

---

Adam, I found this pic at L.H. Are these the 299's you have access to?

http://www.hostboard.com/forums/hbmc...2012/11/16.jpg

Quote:

---

Originally Posted by voice of the theater

...

Adam, I found this pic at L.H. Are these the 299's you have access to?

...

Lucky guy!

---

hi v.o.t. ,

those are indeed the drivers i have access to...
don't own them but they can be made available
for conversion into 2 or 3 way systems.

chap in question has means to match the drivers
according to frequency response etc. same fellow
has solid folder of official altec box plans - hope
to have a good read at some point.

fellow with the model 19's is local number one
for valve guitar amp repair - also sees all sorts of
hifi esoterica - mean to post some pictures at
my picasa photostream; lovely guy too.....

thanks for checking in, all thoughts welcome,

cheers,

a

Quote:

---

Originally Posted by Geekstar

Certainly true...but what were you planning to do about it? You are stuck with what the factories made.

I'm not a horn designer...more of a junk collector and listener.:p

---

hi geekstar* ,

knowing curve from phase plug to throat suggests matching rate of
expansion to that flare rather than starting a second curve from the
exit of the compression driver. probably limits family of curves to
choose from, (maybe helpfully), or points towards compound or
hybrid flares..... (like dave fastlane's 'contrac' for klipschistes)

relate to the junk collecting and listenerhood - am barred from technical
depths by getting the music genes instead of the maths ones....

friend who is learning hornresp too busy to help at the moment - really
won't be free til january but could find another bod sooner, will hunt
around. simulate - build - measure - listen - simulate ... exploratory
philosophy with this one, experience limited so far, will proceed gently,

cheers,

a



* rhymes with 'jeepster'?

Quote:

---

Originally Posted by adam_ecofan

... is there a plain english explanation for the operation
of phase plugs - jbl radial, altec tangerine, tannoy pepperpot?

same job - different geometry - how does it work?

---

hi all,

pretty good explanation here - can't judge veracity
but at least wrapping my eyes round the idea helps
clear the picture for me,

cheers,

a


Phase Plugs

hi all,

with the possibilities multiplying
time to focus.

driver 909 crossed over at
24db per octave, 1200Hz

horn 1: 600Hz round tractrix
horn 2: " square 'trix
horn 3: " radial

friend has figured out how to
get solidworks to drive a router
from the algebra - will buy a
sheet of the truck decking -
shoot for density.

still to consider: round to sq
& machining first section of
throat for ease of comparison.

let me know if i'm more or less
on track...

happy trails,

a

hi all,

with the possibilities multiplying
time to focus.

driver 909 crossed over at
24db per octave, 1200Hz

horn 1: 600Hz round tractrix
horn 2: " square 'trix
horn 3: " radial

friend has figured out how to
get solidworks to drive a router
from the algebra - will buy a
sheet of the truck decking -
shoot for density.

still to consider: round to sq
& machining first section of
throat for ease of comparison.

let me know if i'm more or less
on track...

happy trails,

a

hi all,

went and had a good look/listen to the
'lion rockers' soundsystem - very impressive
piece of work. all vinyl, no digital playback...

didn't get to chat about it - serious sound
pressure at work - good thing i like dub & roots.

not high fidelity though - difficult room to
play in too - hope to hear the rig in an outdoor
setting soon. (system lives out at one of
auckland's black sand beaches.)

still room for a super clean valve top end
i reckon....

regards,

adam

hi all,

finally got to play some records over the altecs.
had been playing through laptop til now - hooray!

can see why full eq useful for a show - rig in
double garage - very clear sound for some
distance around the building.

good records jump out, have to throttle back the
rougher ones. scale, dynamics all there - craving
triodes on the tops though....

looking into laminating solid timber for horns -
more experienced woodworking friend quite keen,

anyhow, pictures to come over on the
audio heritage thread,

cheers,

a