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Folded horn cabs?

#21
I used one of those Fender 4x12's back in the mid-70's driven by either a Fender Bassman 70 or a Showman amp. I don't think this is a folded horn design. Just a angled baffle thing.

As I (and others) have said before, these things had a weird dispersion thing going on.

I also used one of those Cerwin Vega horn cabs, back in the day (borrowed from a keyboard player friend of mine). I did like the sound of that cab very much.
 
#22
That must have been the worst thing Fender ever made but it summed up the problem in those days which low power handling by the speakers.
I restored this one recently, stripped down the quality of construction was a joke

125hvdt.jpg
 
#23
Found a 15" JBL folded on Ebay de.last year around Nov.for 80 Euros.
Never owned one before but saw quite a few in the 70´s,and just had to have it.
Untill now have only used it in the practise room with the band with a Peavey MK.4
Ampeg Pro 5,or a SWR 750 with an Ampeg 8x10 linked up.
The sound is what you would expect,but they´d.. most likely carry you away in a white suit. At the next gig I might have the chance to use the JBL with my Ampeg BA500 combo,well see Ill let you know.
Woffle
 
#30
which was the 1970s. PAs weren't nearly so powerful and, aside from the truss-busting SVT and a few Sunns, most pro level amps were around 100-125 W. There were very expensive exceptions - Marshall Majors and the really big Hiwatt 200 and 400 beasts. Those horns could throw a lot of sound a long way, albeit in a pretty woofy and indistinct way. PAs do most of the heavy lifting now, but it wasn't that way 30+ years ago. DI in a club in those days was unheard of.

Unfortunately, playing one in a bar was usually a comic disaster. It happened to me once, when I had to use the headliner's amp rig with a big ol' Ampeg V4 horn cab. Couldn't hear myself worth sour owl crap on stage, and when I cranked it enough to hear myself I was blowing the heads off of people 30-40 feet away!:eek:
 
#32
Hifiguy said:
Unfortunately, playing one in a bar was usually a comic disaster. It happened to me once, when I had to use the headliner's amp rig with a big ol' Ampeg V4 horn cab. Couldn't hear myself worth sour owl crap on stage, and when I cranked it enough to hear myself I was blowing the heads off of people 30-40 feet away!:eek:
Click to expand...
The V4s, and similar Acoustics, were knockoffs of the JBL Keele W Bin horn, which were described by inventor Don Keele as:'a usable response from 32Hz to 400Hz... can be used as woofers in discotheques, bass guitar or organ pedal systems...Because of the inherent midrange coloration of any "W”-horn design, the recommended crossover frequency is 300Hz or lower.'
They never should have been used alone. :rollno:
 
#34
Bassman62 said:
Wasn't the scoop the JBL 4520, we had a pair of the 2x15 versions in a local nightclub.
Click to expand...

'Scoop' is the name given to any rear-loaded folded horn with a curved lower reflector, which resemble a sugar scoop. They don't function differently than any other rear loader, which is fair to middling.
 
#35
Bassman62 said:
That must have been the worst thing Fender ever made but it summed up the problem in those days which low power handling by the speakers.
I restored this one recently, stripped down the quality of construction was a joke
Click to expand...
Dear God. I owned one in the mid 1990's. It flat sucked. I agree the quality of construction was a punchline, too. I think the baffle was 1/4 inch plywood and cabinet was particle board. Hooray for staples and bad aim.

Mike
 
#36
I used the big JBL 4520 dual 15" in the late 60's. It was a massive box powered with two 2205 drivers. The size was similar to one of Bill's 36" wide T48. At 260 pounds the JBL was far heavier than a T48, and doesn't perform as well.

However, a rear loader is still a real loader, and has the problems inherent with the design. Perhaps bass cancellation might be less an issue with the 16 small drivers.

I went digging for the PJB response charts, but can no longer find anything other than those in the 2004 catalog. The 16H is not listed. The use of multiple drivers does work, but I have to think there are serious comb filtering issues. An off-axis plot would be interesting to see.

I've been a fan of PJ for a long time. He is a stand-up engineer, and I commend him for publishing his response plots. I'd like to see the new ones, as the 2004 catalog is becoming dated. The PDF directory on his site is hidden, so one has to dig for it. Only Catalog 2007 is present.
 
#37
The Cerwin/Vega B36MF was the one with the 18" in a folded horn and the 12" mid/high driver. One can imagine what the "MF" stood for, eh?

When I'd only been playing for a few months, our band did an open mic kind of thing where the house band's bassist had the Acoustic 360 rig. I knew enough to know it was loud, but not much more. This was a rather small bar, with the stage set on the long wall, so we weren't really having to throw very far. We did about five songs, and the others in my band kept telling me to turn up, which as a young bassist in a band of more experienced musicians (so I thought), I obliged...

After we were done, I talked to the house band's bassist and asked him how it sounded. Carl said "I don't know- I got into watching the beer bottles dance across our table." We got to be pretty good friends, and he played his Acoustic until he died...

jte
 
#38
Spinal Tapper said:
Is this considered folded horn cab? It's a Fender 4x12. This was already sitting at the studio we recorded at last spring - I just threw my V4-B on there (pictured) and we mic'd that bastard up! Pretty nice tone! Saw one on craigslist the other day for only $400.

v4cab.gif
Click to expand...

A Relic From the Dark Ages...

I've seen one of those before, I always thought it was a silly design. Those drivers could hardly be considered Bass Speakers.
 
#40
I had a fascinating email exchange with Phil Jones ages ago when he launched PJB, really knowledgeable guy! Here's the pertinent content:

"We too are excited about the horn cab. it has a couple of major drawbacks. 1. its very heavy 2. its big. Its also not cheap. we've figured about just under $3000 reatil so it wont sell in any huge quantity. Horns to me are the Holy grail of great sound. no matter what they are used for Bass or just listening to music. They have a bad rap over the years because many commercial designs were just bad. Done right a horn can sound better than anything else but they are difficult to make and even more difficult to design because of so many more parameters to consider.

I consider bass in general a problem for us mere human beings. There is no real acoustic instrument except for Catheral pipe organs that can actually produce decent levels of low bass. Us humans are to small to really handle acoustic instruments that could comfortably produce real low fundamentals. Doing a spectrum analysis on a high quality acoustiv upright showed me that there was virtually no energy being produced below 100 Hz! The word in acoustic instruments is efficiency. So when it comes to loudspeakers to produce bass with good efficeincy, they have to be truly massive.

In 1946 when James B Lansing and John K Hilliard unveiled thier monster cinema horn speakers to the Academy of Sound and Motion pictures. The bass loading was actually a vented type. which extended the response down to 40 Hz. This is where the problem lies in producing low frequency with a horn. If you were to take a typical high power 15 " cone speaker and subject it to its maximum power rating at some low frequency , say 40 Hz. The cone would probably move back and forth , maybe one inch. So in a pieriod of 1 hour ( that is if the speaker hadnt yet gone up in smoke) that would equate to the cone having travelled back and forth about 27 miles.(IE 27 MPH.) Sound travels at around 761 MPH. and this huge variation in velocities causes an acoustical mismatch between speaker and soundwave. It would be a bit like playing badminton with sledgehammers instead of rackets! A horn can therefore be considered as an acoustic gear box to the speaker.Translating the high pressure , slow movemnet of the cone int a low pressure high velocity sound wave. Bass waves are huge . The open E string on a bass is nearly 28 feet long.This is where the problem lies. The smallest a horn can be is about 1/4 wavelength of the lowest radiating frequency for propogation to take place. So for a 4 string bass that is 7 feet long. many so called bass horns are not true horns at all.

In order for a horn to work at high efficiency the ratio of diaphragm area to throat must be greater than 1:1 and often in comercial designs ,this is not so.It is usually a 1:1 ratio and that is just a directive baffle and not stepping up the velocity of the wave. In my design I take advantage of the greater motor force of small multiple units. That means I can load up the cones with a 4:1 ratio. On many lesser speakers that would not be possible. The driver would go into a "stall" mode as soon as the air load becomes to great. Kind of like riding a bicycle in high gear , great on the flats to go fast but as soon as you start climing a hill, you had better have strong legs. The other two factors in horn design for low frequency cut of are the radiating area of the mouth and the flare constant.If the horn expands too quiclkly the low frequency wave will not propogate. If the mouth is too small the efficiency will suffer greatly.

Apart from efficiency, the other great thing about good horn loading is the lower distortion on the cones due to less excursion. ( less variation of the parasitic inductance of the voice coil which can modulate the upper mid range frequencies. Group delay is down to some frequncies arriving at some later pieriod in time. The 16 H bass has to go an extra 12 feet so it definitly has group delay. Hearing horns with this character makes you immediatly forget abvout figures and specs. The sound will take over and you will find it possibly intoxicating. There is no perfect speaker or we would all be using it by now and horns even good ones have problems but there is something magical about great horns and sometimes it's unquantifiable . when you hear it you instinctivley know its right. Back to the 16 H the rear horn works to around 120 Hz but it is definitly not audible as to where the back and front of the speakers crossover."

I'd love to hear one, I'm sure it rocks!

Alex
 

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