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

[adam_ecofan]

hi all,

this is my first post here, pleased to meet you.

i have a pair of altec- lansing A700's* and would
like to reuse the drivers in a new project.

i would welcome any suggestions that would help
me narrow down the options to at least the most
interesting ones.

i have access to CAD/CAM equipment and some
help with electronics, testing and measurement.

don't have to get it all right the first time, happy
with idea of system as work in progress.

i'm not an audio extremist but i've been told my
hearing has been ruined by triodes...

warm regards,

adam

* included with the A700's were a pair of 9444A
power amps and matching electronic crossover

#if this thread should be in diy can it be moved?

[adam_ecofan]

hi all,

i should add that i can arrange to have system
elements tested in anechoic chamber at the
local university - possible then to make useful
comparisons between alternate flares.

A700's in current form are clearly for sound
reinforcement - excellent vocal clarity and
long throw but very uneven coverage pattern
in the treble/upper mids... not very hifi.

i hope to run triodes on the top, open to
suggestions for bass/mid power and the
big 9444A's could run a sub-bass channel.

thanks for checking by the thread -
all thoughts are welcome.

warm regards,

adam

[adam_ecofan]

hi all,

here are some pictures - firstly the A700's on location
- a friend's warehouse apt allows plenty of space for
experiments. speakers on top of 'free to a good home'
(h'onken?) bass cabinets (drivers to be sought out).

and also pictured: a local valve guru and horn enthusiast
built this mono speaker stack from things he only has
one of - an altec 605 and a vitavox metal horn, tweeter is
a goodmans 'trebax'; powered by a rare leak valve amp
passive crossover visible as is the camera-shy builder's finger.
perfect for his vintage blues cuts, not bad for a workshop system.

he's an altec fan and will be helping with the A700 conversion,

cheers,

adam

[theophile]

Ask your questions here:

http://www.hostboard.com/forums/f700/altec-users-board.html

There is no shunning of Altec questions on that board.

[adam_ecofan]

hi all,

thanks theophile, will follow the link...

also have a friend with jbl woofers to
recone - has substitute woofers in place
will post pics of his monitors,

cheers,

adam

[adam_ecofan]

hi all,

here are a couple of pictures of a pair of the
cnc routers i'm lucky enough to have some
access to.

currently considering different material options
keruing - a malaysian hardwood used as shipping
container flooring (see rey audio studio monitors),
hoop pine - an australian product, sustainable and
similar to birch in weight and tone; third possibility
is high pressure phenolic and kraft paper laminate
- now with black core (up to 18mm thick...)

looks like shooting for 800Hz xo with a 400Hz horn
- any thoughts welcome,

cheers,

adam

[1audiohack]

Hi Adam;

Welcome to Lansing Heritage!

I dont know how I missed this thread, I'm looking forward to seeing what you build with all that you have available to you. I'm no Altec expert but I'll bet someone who knows more about Altec will pipe up.

All the best,
Barry.

[Earl K]

Adam,

- With the components you have on hand, I would build the following ; ( click the pic to go to the relevant thread, located over at DIY ) .

http://www.audioheritage.org/photopost/data//500/NewPair_of_Brociners_covers.jpg (http://www.diyaudio.com/forums/multi-way/169755-what-would-you-do-cabinet.html)

- Give that thread a very careful read . The OP ( when compared to yourself ), was in an even far less informed position about diy , ( apart from him being a long-time recording engineer ).
- He ended up with these back loaded horns ( BLH ) that just knocked his socks off .
- His on-going excitement ( stated throughout ) of discovering what a fairly accurate high-efficiency system can do ( when coupled with flat HF response ) , is really quite contagious ( or at least it should be ) .

- The linked-to-thread (http://www.diyaudio.com/forums/multi-way/169755-what-would-you-do-cabinet.html) has everything you need to proceed, including blueprints and a crossover schematic tweaked by Zilch for higher efficiency .

- So you know, the Altec 515G is not a suitable driver for a Bass Reflex ( BR ) cabinet assuming you actually like bass ( meaning you'll need to sell them if this project doesn't have any appeal for you ) .

- While he ( Wilberforce ) used different components , the Altec 515G is very comparable to the JBL 2220a ( that he used ), in what they both functionally do best ( which is perform as horn drivers ) . Using the Altec 909 is workable in this project .
- The horn used in this project is obtainable from Parts Express ( here ! (http://www.parts-express.com/pe/showdetl.cfm?partnumber=245-625) ).
- Since I prefer to listen to Radials ( such as the following variants ), I thought I should mention that you might want to consider substituting in a custom made Yuichi 480 ( if you're building skills are up to it ) .
- Either of the following could look spectacular sitting on top ( or inset into the baffle board ) of the Brociner LF horn .
- Click the pics ( for some inspiration & info ) ;

http://www.geocities.jp/arai401204/Horn/A480/A-480Web.gif (http://www.geocities.jp/arai401204/Horn/A480/A480.html)http://www2.117.ne.jp/~y-s/images/SS-500-1-web.jpg (http://www2.117.ne.jp/~y-s/SS500.SS300katarog-e.html)


:)

[adam_ecofan]

hi all,

thanks earl - site so thorough here can be hard to find
just what is needed.

i've been to a lot of rock shows in my time - hard to
beat a horn loaded system for punch and dynamics -
early favourite pa the jbl hla series; current favourite
sound reinorcement is the l'acoustics 'vdos' system -
super clean - saw a great show with 'kraftwerk' -
closest to a high fidelity sound i've found live so far.

and reading about pattern control makes radial horns
seem very sensible, not least the dramatic reduction
in size and woodworking effort.

plan to work on midrange horn first and come back
to bass module in the new year, i'll digest the
threads and get back to you all,

kind regards,

adam

[adam_ecofan]

hi all,

in transforming the horn flare from a round
to rectangular profile - where should the
transition take place?

in the very short steep section at the exit
of the driver or very smoothly along a
greater length of the flare?

the yamamoto horns have a very sweet
looking bronze adaptor at the throat -
is that the most suitable technique?

i have a friend that runs the cad dept for
a manufacturing jeweller and their additive
prototypers are good to 0.002mm if a wax
positive for a casting needs to be done.

also, the QSC waveguides from parts express
would be a very handy, and affordable, reference...

all thoughts welcome,

warm regards,

adam

[Earl K]

Hi Adam,

Your question is a good one ( in fact it's one of the many 64,000,000. dollar questions in horn design ) .

- If you can match the Yamamoto approach ( which "looks" to be the best ) / then I encourage you to do so .

Having said that, I like the Emilar EH500's practical approach . The entry to that horn bell proper is a simple 2" round hole ( nothing could be more simple to construct ).
- As a consequence of that 2" entry being right into the horn / a bunch of obvious diffractions must be happening ( a word to the wise, diffractions are a dirty word these days with the audio PC movement ) .

- Any 2" exit driver can be bolted on directly to the Emilar , while others such as my Altec 288 need a 1.4"-2.0" adapter ( available on the internet from time to time ) .
- A 1" exit driver needs something like the JBL 2327 adapter to mate up with the Emilar horn bell .

- Since I get spooky/killer imaging from this setup / I'm required to stand behind the opinion that these ( circular to circular cross-section ) adapters don't hurt the sonics much at all ( when all the expansion to the rectangular shape of the bell / occurs completely wthin "said" bell and not the throat ) .

:)

[adam_ecofan]

hi earl,

matching yamamoto... well, shoot for the stars and all

might not have to go to casting - have been thinking
about method for fabricating throat section:

- rectangular former of required depth
- positive cnc'd plug in shape of throat
- use resin or similar to set plug in box
- remove plug leaving throat section
- embed means of fastening at same time

finish resulting block with smooth surface at the
faces where it meets the driver and flare.

emilar horns are very interesting - my friend who
can wrestle with hornresp was trying to explain
that flare to me - picture worth many words.

also, yamamoto makes their horns in two halves
- i was thinking of four pieces for flare proper,
with enough material thickness to allow a good
wide join between sections and a broad surface to
mate the throat to; run the joins n-s, e-w...

should make milling up the pieces a little easier,

thanks for the input,

adam

[adam_ecofan]

hi all,

some pictures of the 'doodles' my graphic designer
friend was making with the big formiga solid printer
at tech. objects were used for various pamphlets and
other publicity for the school.

not super smooth output but certainly very precise,
major advantage is forming shapes too difficult to
machine - perhaps suitable for horn throat experiments.

warm regards,

a5734357344573455734657347

[adam_ecofan]

hi all, the chap who supplied the A700's has turned up this group of rather battered looking altec 299s available for further development in horn project - may need some t.l.c. though. also, picture of the altec bin my other friend has in his bass/guitar rig. had a korg synth from the 90's hooked up to it - plenty of welly - rattled the cups off the shelf in the kitchen... cheers, a.

[Earl K]

- You should borrow ( or buy if necessary ) that VitaVox radial horn ( top right of the first pic ) so that you can copy it's dimensions/curves ( etc. ) .
- Then you can make a pair in wood for yourself .

- That particular VitaVox horn is not all that different from the TAD TH4001 horn or the Yuichi 290 . Reasonable speculation would be that it acted as a model in the design for one ( if not both ) of those horns .


<> EarlK

[adam_ecofan]

- You should borrow ( or buy if necessary ) that VitaVox radial horn ( top right of the first pic ) so that you can copy it's dimensions/curves ( etc. ) .
- Then you can make a pair in wood for yourself .

- That particular VitaVox horn is not all that different from the TAD TH4001 horn or the Yuichi 290 . Reasonable speculation would be that it acted as a model in the design for one ( if not both ) of those horns .


<> EarlK

hi earl,

thanks for that tip - will investigate;
owner of the mono stack very nice
chap - fixes valve gear - guitar amps
and hifi; he had shindo, quad, macintosh
and more the last time i visited.

also seems to be a multicell horn tucked
behind the altec drivers - just visible
in the back of the picture - didn't notice
till i looked back at the snap...

cheers,

a

[adam_ecofan]

hi all,

visited my friend with the vitavox for a closer look.
he wasn't sure of the model number but here is a
link to a v.v enthusiasts page with more info:

http://website.lineone.net/~empson/RH330.html

interesting construction - looks as if the horn is
formed in two parts - an outer shell and an inner
contour; however the info reports the horn is
diecast aluminium.

there is a short adaptor section from driver to horn
allowing various drivers to be fitted to the unit.

the round to square transformation takes place
in the relatively short length between driver exit
and horn proper.

cutoff is given as 330Hz with a 90h x 30v deg
polar response,

cheers,

a

(options proliferating, will look at yuichi next...)

[adam_ecofan]

hi all,

have been looking for intelligible non specialist
explanation of operation of phase plug, found
a clear - and well - illustrated page of a fellow's
experiments with plugs for dynamic drivers.

helped me get a bit closer to understanding,

cheers,

a

http://www.hostboard.com/forums/f700/179870-909-8a-400hz-tractrix-horn/index4.html

[adam_ecofan]

hi all,

asked more about the formiga object printer
pictured in the thread: prints in nylon to
1/10th of a millimetres. i think sufficient
finesse for what might be needed...

pictures of humble new dwellling for
A700's to come,

cheers,

adam