|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
220.237.36.68
Hello everyone,After many long years of frustration with just about every commercially available high efficiency loudspeaker that I could find, I have decided to build myself a set of speakers based on vintage parts.
I have been fortunate to have obtained the following:
1. a pair of Altec Hollywood 515 drivers (one is totally original, the other looks like it has been re-coned,
2. a pair of Westrex 8 cell horns (with plenty of tar added),
3. a pair of Altec 288C compression drivers that will soon be re-magnetised and have the diaphragms replaced.I would like to build some cabinets for the 515's but I need some guidance regarding what works best. I have heard that Onken designs when executed well, can give a very detailed sonic presentation but may not be too musical. What are your experiences? Any suggestions regarding volumetric capacity, ports, bracing, materials, designs, weblinks? Thank you in advance. George.
Follow Ups:
Hi George,I'll echo JeffreyJ in recomending bass horns for the 515s; he has been there and done that and knows his stuff. Though you might not extend as low with reasonably sized straight bass horns, they will provide clarity, dynamics, efficiency and low distortion to match your mid/h.f. horns and drivers.
It is a pity that so many "horn" systems use a direct radiator low end as a concession to size. For those of us used to listening to bass horns, the bottom end of those hybrid systems never seems to keep up with the horns dynamically. The air moving requirements become progressively more demanding at lower frequencies (quadrupling each descending octave), and just where the demand is becoming acute these systems switch to a drastically less efficient radiating scheme. Having to pad the horns down about 10dB to match the bass section is another undesirable aspect.
My nephew runs 288-16K drivers on Altec 805 tar filled horns with great results. His crossovers pad the horns down several dB to match his Karlson bass section, but he uses small value bypass caps (1 or 2 mfd.) to let the highs run free. This technique works with systems using bass horns as well, as even then the mighty 288s usually need to be padded down some.
*** It is a pity that so many "horn" systems use a direct radiator low end as a concession to size. For those of us used to listening to bass horns, the bottom end of those hybrid systems never seems to keep up with the horns dynamically.So, I ma one of “those”… You forgot to mention that to mention that a PROPERLY IMPLEMENTED direct radiator solution is WAY more successful then any of SEVERELY COMPROMISED BASS horn.
*** Having to pad the horns down about 10dB to match the bass section is another undesirable aspect.
Way you have to have mismatch. The line-array give virtually the same sensitivity + 3dB form the cylindrical wave + 100000 times more manageable radiation. Did you ever seen an impulse response from a bass horn?
a bad basshorn is not a good thing. How does one properly design a ported system starting with driver choice?BEST
Kozlovsky Folk SongWolfgang Windgassen
1964
Brian Hymel singsMax's aria from Der Freischutz
Bryan Hymel sings "Asile Hereditaire"
from Guillaume Tell
seems to me that a Karlson's driver isn't flapping about doing ~nothing as happens in direct radiator and an average low mass strong motor driver will take several hundred watts for about 1/8" peak to peak movement or less on a robust drum solo to produce a viseral experience.Exemplar may have used a low fs 515 in their re-tuned (and boosted) K15 subwoofer. Jeff said it went ok to 18Hz.
I'm somewhat surprised with all the hoopla for pipehorn, etc. that no one (online) attempts to build new coupler. Seems they would find some application.
its easy to get LF extension and good graph in reflex.
Helloi have played around with altec horns and woofers for some time and here are my observations.
1. Since you have parts you want to build from, I wont suggest
the Model 19. But try to hear this so you can use it as your
reference on balance. Your A5 when done right
should have this balance but with better midbass.
2. the 500 xover point lends naturally to a midrange
emphasis which is a bit hard to balance. i found the 800 point
easier to work with.
3. A5 (also called 825 cabinet) maybe the easiest way to get good
sound for an altec wooofer (be it 515 or 416). Its got
a magic midrange. It would be wise to make this your starting point
(it might be your end point too). In the presence region of
250-800 its
very hard to beat. Note that most of
the Edgarhorn TitanII and other
bass horns are better in the 80-200 region but they dont
really compete with the A5 from 250 upwards. Note that from
150 downwards, the A5
has a 'shelved bass' and needs to be augmented by some extra
woofers or subwoofers (pair of large 15 dbl woofer boxes
would work nicely and are more natural-sounding
than a pumpy-subwoofer)to get better sub-150 bass.
4. The 288c is a great compression driver. but most of
the horns that fit it
are too big for ordinary rooms. In my experience the
288c is at its best in
need a huge room (greater than say 20x30x10). the 288c with
its big
horns needs 3 woofers a side to balance it out (2 per side in an
a2 is not enough --- still gives too much midrange oomph).
5. The Hirago xover with its notch filter
is a worthy atttempt to tame the 288&its horn.
but i found it taking away too much music.
i got much better results by going to a jbl 2440 and using
a smaller domestic-friendly horn. for examples, you can choose
from jbl2397 / bruce-edgar 500 saladbowl horn / rca-fans conical
700 alumminium horn. All of these are easier to get right than
the big altec horns as well as being more practical.
6. If you want to stick to altec, I suggset the
smaller altec horns and altec 1" compression might be
a better starting point than the 288c (note that the
smaller altec horns
and drivers are a bit spitty compared to the jbl 2440 (great
by any other standard)
7. I would recommend the Model 19 crossover (N850? N12850?). These
are 8ohm xovers but can be used with great effect. altec made
a variety of xovers -- be ready to experiment. i did not have
much luck with the jbl xovers.
8. if you go with jbl 2440 you will have to add a tweeter & cap to
it (fostex is a good start point here).
9. be prepared for some amount of experimentation (2-100 years?)regds
munna
Hi Munna,I am the guy who bought your td124. Is there a way we could get in touch I am trying to build some cabinets for some vintage JBL drivers & could use your advice.
Thanks,
HI Matt
feel free to call me at 973-482-1480. i did a lot of a/b between altec and jbl woofers in the beginning but decided that altec woofer were more musical and --- to me -- more accurate (even though the jbls useally went down lower). after that i tried out many of the altec brands and finally settled on the 515b and 416z. so my jbl woofer comments are probably fuzzy. i confess to having lost track of jbl woofer names and cabinet models. for low bass (20-40), i prefer tad to jbl. note that jbl made wide variety of cabinet and if you are a jbl-woofer fan, it would be worthwhile to get familiar with jbl pro catalog. my friend who made most of my cabints (jack kuo -- who did your 124 base) has moved to atlanta. i am mostly out of audio now.
rgdds
munna
Some very good advice. I do respectfully disagree on the suitability of Altec 288s and multi-cell horns in houses, I used 288-1005s to my complete satisfaction in a moderately sized rec room. However my satisfaction is just that, mine.
hi Tom
looking back i should have played with the 500 crossover a little more. but 500 is so sensitive. no where to hide when its not perfect. i was on the point of starting to experiment with changing coils & resisotrs when i bagged it and went with the 800 point and its easy forward progress. but no regrets. i am fairly happy with my horn balance now. it holds its own (on balance) against respected monitors like m40, atc20, bc1. of course it beats
them on almost every other parameter.
rgds
munna
Hi George .
nice to hear you brought them . so yeah welcome to the Melbourne horns club .a few set will up and running soon .
I could recommend you build the Onken boxes . I have heard them with the 416 drivers and they have better bass than what I have which is the Altec 825 cabinets . they definately go deeper .
my set up is Altec 825 cabinets with 416s and altec 805/288-16k and hiraga Xovers .
if you want to hear them before you decide which to go then email me off line.
regards
Peter
PS: we have meet in Mohan place .
LT--Have you heard 515s in Onkens? I dunno how they'd work but mind that an early 515 with it's paper hinge and phenolic spider is a totally different animal than a 416, indeed any 515 is a way different animal. So you can't assume the 515s will work in an Onken.On the other hand if you've experience I'll defer to it.
Hi Tom.
I haven't but do the search . there is lot of poeple use the 515s on the Onken with great results.
Cheers
LT
Greets!Yeah, you're going to have to trade quite a bit of efficiency to get a 515 to 'fill' up any cab tuned to near/at Fs unless it's the early 55-60 Hz Fs unit and will require it be EQ'd in the amp for best performance. A high output impedance amp with adjustable DF up to ~25 ohms is your friend here.
George,I'm in a similar dilemma and I believe we are local. I'm a MAC member. I don't get to Mohan's very often (only a couple of times) but I've met Goran who responded to you below.
I have a compression driver loaded horn that I'm using above 450Hz. Now I have to figure out what to do underneath. An Onken was the first thought as it saves building a sub, but the 70Hz straight horn that JeffreyJ mentions has crossed my mind too.
Anyway, we should have a chat as it might be that we move in a similar direction.
Cheers,
Jeff, you should come to Mohans audio meeting in March... The horns we are going to listen are using Altec 288 and I think also Altec 515 drivers. It would be nice to see you again. You may be surprised to find out that apart from me and Justin there are another four people in Melbourne who got Slagle's autoformers.
Hi Goran,I may make it, but I may have heard the system by then. Am working on getting my system going. Send me an email. You should come around and hear these big Azurahorns with compression drivers.
Cheers,
put them in a front horn... it would be rather short... like, say a 75Hz horn... you would still get that wonderful 515 sound up to your crossover point... and then *good* woofers below that... you have to add something to the bottom anyway.. I don't think they will do what you want from 20 to 500 in any cabinet without eq and that would kill the efficiency even more... and use up the little travel you have... maybe even damage those wonderful old beauties..plus, the front horn will bring the efficiency UP to close to the horns... a good thing as padding down is always sonically tricky...
so...
288's in tar filled 805's from 500 up..
515's in a 75Hz horn from near the flare frequency to 500...
good subs below that..
add super tweeter for fun...just my opinion... but the opinion of a guy who has 515's and Onkens and basshorns and 288's and rca's and jbl's and.... :^)
and I can help you with the design of the basshorn.. it would only be like three feet deep.. and a mouth of like 24 x 30... (off the top of my head)... and simple construction... approximations are fine for these frequencies...
Hi George,
Nice to see you've joined the horn/compression driver club.As you know I have a pair of 515 drivers in my Exemplar Horns, unfortunately when you heard them last time at my place they were not set up properly (out of phase). Now after years of using these speakers I realised that Altec 515 could give you wonderful mid bass and midrange but you will miss a very deep bass. I solved this issue by adding a pair of 15" sealed subs made by Bruce Edgar. Now I have a really deep bass too and it's very fast and controlled. Probably not as fast as horn loaded subs but still pretty good.
I am moving to the new place in 4-5 weeks and you can come over to listen...
I am sure you will like the sound now.Are you going to the next audio meeting at Mohan's factory?
I think Brian will bring his horn speakers...
Greets!What's their Fs? If they are the original cones with no separate surrounds, the few I've measured were ~55-60 Hz, so strictly for mid-bass or huge bass-horn apps.
I used 515Bs in 825 cabinets and I think they made the finest upper bass and midrange I've heard. However the lower bass is weak and the large size of the cabinet is wasted; as Alfredo said I augmented the 825s with large subs.So it would probably be better to put the 515s in 816 cabinets which are basically just the upper part of the 825, the part with the horn. Then use the 816s with some powerful vented subs below 100-150hz or so.
Or build 825s and do the mod where you use the bottom volume of the cabinet for an 18" JBL sub. Then you'd have it all in one box with deep, powerful bass. Alfredo and I were talking about that just last night.
Here is a link to Hiraga's EQ Crossover (towards the bottom of the page).Alfredo
This may give you some ideas...Hiraga, BTW, is considered to be the father of the modern horn + triode movement, so I guess he knows what he is talking about. If you can find a copy, his book on loudspeaker design and theory is great reading, but is only available in French.
The obvious answer is the Hiraga set-up. It uses a 515B in a modified 828 box with a passively equalized 288 on a 15 cell horn. I think your 8 cell horns would respond to the same sort of eq.Joe Roberts used to have the Hiraga schematic on his Altec site.
Hi George,Nice set of "old" parts that you got!
The first thing it reminded me of was Tom Brennan's A5's that he had when he lived in Chicago. Produced wonderful sound from 100hz - 10Khz. Bass was supplemented with 4 additional 15's.
I've seen people use the Onken cabinet but never heard one in person. I believe it's just a "glorified" bass reflex cabinet (my opinion). You could probably use one of the free speaker builder calculators to determine a box that will satisfy your needs (sealed or ported).
I have also heard these can sound good on an open baffle.
Now I use the 515B in custom Altec 825 cabinets and the midbass/midrange is incredible but the cabinet size is a waste for what it is doing (only 120hz - 800hz). You could get the same results using your own horn design or something from Bruce Edgar that is probably half the size.
A few things to remember:
1) The 515 (especially the early one you have) is not really meant to be a low bass driver and you may need to supplement the low end with something else (if you desire low bass).
2) Your probably going to have to attenuate the 288 to match the 515 (more so in a typical enclosure than with a horn).
3) Some people use a tweeter above 10-12Khz where the 288 drops.
I'm sure others will give you some more feedback as well.
Good luck and let us know how it goes (hopefully with some pictures of the end result).
Alfredo
This post is made possible by the generous support of people like you and our sponsors: