Horns

[Zene]

Hi Gang .. Just scored some horns that
I cannot identify. Close in the style of 811B's but smaller. Cast alum, 3 segment 17 3/4" x 7 5/8" and 9" deep. 4 bolt (43mm spacing), 1" throat. Only marking is a raised cast "Made in England". Did get 2- 811B horns in case the little ones fizzle. Sorry cannot do pic. My Hawkeye Brownie doesn't cut it for this new fangled stuff.
Also, purchased three 806-8A drivers that need diaphrams. ASSume are worth new diaphrams, and is there anything special I need to know before proceeding? OH! Yes, 4 bolt to two bolt adapters? Thanks, Zene

[bfish]

Hi, Zene,

The only British horns that come to mind are Vitavox and Tannoy, but I'm sure there's others. Pictures......

Your 806s are definitely worth putting to use, as long as they're not rusted up or otherwise trashed. They're only slightly less output than their bigger brothers, which often doesn't matter since they usually get attenuated anyway for hifi. You can buy 'phragms for self-install (instructions at GPA website), or send GPA the drivers, and have the added bonus of remagnetization when they install new 'phragms (recommend).

Assuming the horn throat is the same exact diameter of the driver exit, you should try to mount the driver directly with no adapter, either by using 2 of the existing holes, or drilling 2 new ones (easy in alum). Check the horn mounting face for smoothness and flatness, you may need to file it flat/smooth or fab a gasket for it. When assembled, look down the throat to make sure the driver exit makes a smooth transition to the throat.

Being slightly smaller than an 811, the horn may have a higher cutoff frequency, I'd guess about 1kHz. The biggest difference is the depth (length), by a little over 3". That's weird. If it's heavy enough, they probably won't 'ring' bad either.

[Old Guy]

This is going to be a rough one to identify.

Those are probably either Fane or Celestion stuff from the 1970's. Both of them had something similar. I didn't buy any at the time because the British Pound went up and down like a roller coaster. By the time a project was finished planning, the price could have changed significantly. So British stuff from that time frame just didn't sell well here in the States.

As Bfish said, pix are a must. An acquaintance is head designer at Studiomaster- I could possibly get some ID help from him but without the pix it's kind of a lost cause.

[Zene]

Thanks, Guys. Will get pics as soon as I can. I have a third 806-8A to try on one. Just tried a quick R/L mono comparison. The Fane (if that's what it is) ***** . Lifeless, no articulation, no highs. Need I go on? But, still might have a place somewhere. I have more than a few screwy ideas for theater sound.
Mean time .. you've got a convert to 811B's w/the 806's. Some of us are just slow to get the drift. And, I've been building horns since 1972. I got them with the smaller horns. They kick the **** (prob be bleeped) out of my P.audio 12" coax, cleaner, smoother, all around better. They are powered by stock T-Amps (Old Man: your favorites. tee hee), and are still awesome. Cannot image how they will sound with modded Super T's and the JBL 34 cabinets.
I was told I need a cap on the 806's whether I use an electronic crossover or not. If true what value?
Old Man, BTW ... now that the mids are settled, I still have the Altec 602's to recone to something. A guess as to what might work in the JBL 34's? I picked up a pair of PWK K-33's to try in them, but doubt if they will get to 800hz, which I ASSume is good starting point for the 811's. And of course the P.Audio JBL 2226 clones. Zene

[just me now]

look up the ALtec Engineering Technichal Letter number 205 -- it provides the Atlec graph for these values at different xover freqs...

[Old Guy]

Originally posted by Zene:
Thanks, Guys. Will get pics as soon as I can. I have a third 806-8A to try on one. Just tried a quick R/L mono comparison. The Fane (if that's what it is) ***** . Lifeless, no articulation, no highs. Need I go on? But, still might have a place somewhere. I have more than a few screwy ideas for theater sound.
Mean time .. you've got a convert to 811B's w/the 806's. Some of us are just slow to get the drift. And, I've been building horns since 1972. I got them with the smaller horns. They kick the **** (prob be bleeped) out of my P.audio 12" coax, cleaner, smoother, all around better. They are powered by stock T-Amps (Old Man: your favorites. tee hee), and are still awesome. Cannot image how they will sound with modded Super T's and the JBL 34 cabinets.
I was told I need a cap on the 806's whether I use an electronic crossover or not. If true what value?
Old Man, BTW ... now that the mids are settled, I still have the Altec 602's to recone to something. A guess as to what might work in the JBL 34's? I picked up a pair of PWK K-33's to try in them, but doubt if they will get to 800hz, which I ASSume is good starting point for the 811's. And of course the P.Audio JBL 2226 clones. Zene

<font size="2" face="Verdana, Helvetica, sans-serif">One potential down side to using blocking caps, is that under high SPL conditions, there is a possibility that HF driver diaphragms can bang against the phase plug assembly, because LF damping provided by the amp is also removed by the blocking cap. IOW, the adjacent low frequency drivers can modulate the HF diaphragms much easier then without the blocking caps and possibly damage them.

[Old Guy]

This board does some weird things sometimes. I worked about 15 minutes on a reply, only to have most of it wiped when I hit a key. Not being the world's best, or even second worst, typist this causes problems.

Anyway, here's the Altec TL, or at least the link to it.
http://alteclansingunofficial.nlenet...ers/TL_205.pdf

Times have changed a lot since the 1970's and 80's. Many manufacturers, including EAW, no longer run blocking caps. Amplifiers have improved to where they aren't necessary.

The previous post is a quote from Prosoundweb.

I would suggest trying your HF power amp first hooked to a woofer. If you hear anything when you turn it on, you should run caps.

I haven't run blocking caps on my system for about 5 years now. Seems just fine. Your mileage may vary, and all that.

[cclark65]

I have run my 902's without blocking caps hooked directly up to a 9442 amp without a problem. I am running an active 4way system with a slope of 24db and crossed over about 1200Hz. The only time I had problems they were stress related (the diaphragm shattered) and the one time I hooked up the 1100 watt sub output to the tweeter cabinet accidently (oops!)

I think the back-pressure thing from the woofers is a very valid point. From what I understand, without the amp there to control the diaphragm movement, the lows from the woofers can cause it to bottom out from the sound entering back into the horn and put a lot of pressure on the it.

[Zene]

Good advice always accepted. Caps gone, but will be careful. Zene