streetwise
Active Member
Any ideas on damping this horn its painful in the midrange at high output levels? Clay, undercoat? where to apply?
Altec 811B horn damping
- Thread starter streetwise
- Start date
Register to hide this ad
westend
Audiopile
Most folks pay special attention to the exit flanges of the horn. Placing modeling clay along that flange should dampen any vibration. How are you using the 811? Is it mounted in a cabinet? What driver are you using?
FWIW, when I built my 811's into sled deployment I was aware of folks describing a "ringing" with this aluminum horn. After mounting them and driving with Altec 802-g's, I couldn't hear any ringing. I asked members to describe this sound but didn't get any accurate responses. I still proceeded with mass damping, placing up to 20 lbs on each horn throat. I heard no difference nor ringing between the damped horn and undamped. It may be that the mounting to a sturdy sled and a felt gasket removed the suspected ringing but I have never experienced it.
FWIW, when I built my 811's into sled deployment I was aware of folks describing a "ringing" with this aluminum horn. After mounting them and driving with Altec 802-g's, I couldn't hear any ringing. I asked members to describe this sound but didn't get any accurate responses. I still proceeded with mass damping, placing up to 20 lbs on each horn throat. I heard no difference nor ringing between the damped horn and undamped. It may be that the mounting to a sturdy sled and a felt gasket removed the suspected ringing but I have never experienced it.
Just like West said. I use a sticky backed damping material sold at car audio install stores. I can't remember the name but it comes in a 2 foot long roll in a long triangular box.
Clean the surface, heat it with a hair dryer, and stick it on. The most bang for your buck is the bell ends outside the mounting flange. I've used it on 511, 811, and my 1505s.
Clean the surface, heat it with a hair dryer, and stick it on. The most bang for your buck is the bell ends outside the mounting flange. I've used it on 511, 811, and my 1505s.
elitopus
Addicted Member
I use "duct seal" from home depot. Sold in 1 lbs blocks. 
This is some installed on 511b horns. Same deal with the 811b. It sounded best for me when I built up this "ridge" of clay versus having it more spread out.
Also my horns are bolted on to the cabs which helps quite a bit with ringing. When you tap them now they sound dead
This is some installed on 511b horns. Same deal with the 811b. It sounded best for me when I built up this "ridge" of clay versus having it more spread out.Also my horns are bolted on to the cabs which helps quite a bit with ringing. When you tap them now they sound dead
dc270
Now Off the Reservation
My 811 horns were treated with 1" flexable foam rubber sheets. I custom trimmed them to fit all sides of the horn except the front, then Goop glued them into place. Worked great! You can buy this foam at hooby stores.
I have also read where people buy several cakes of wax, melt them down in a pot, then pour over the top & bottoms to fill the scoop area.
Good luck- bet you will like them after your treatment
DC
I have also read where people buy several cakes of wax, melt them down in a pot, then pour over the top & bottoms to fill the scoop area.
Good luck- bet you will like them after your treatment
DC
Last edited:
twiiii
Lunatic Member
I've seen customers dip them in tar, spray them with a rubber type sealant, and spay them car body under coating. They all seam to work to a point. The most important thing is to raise the crossover frequency. Say 800 hZ for the 500 HZ horn and 1200 for the 800 HZ horn. Asking any horn to perform down to its cut off frequency is a big no-no. HONK-HONK! Altecs 311 horns really sound great when crossed at 700 hz. Of course they are coated to begin with and don't resonate. Altec drivers can handle two times the power if you cross them at 800 and more so at 1200 HZ. The 1.4 inch drivers can handle tons of power when crossed around 700 hZ. 75 to 100 watts for the 291 and 299 drivers, and close to 150 watts for the 290 driver. I really liked Emilar drivers on Altec Horns. JBL not so much. Some of EV 1 inch drivers weren't bad either, but the two inch drivers had some internal throat issues, so we used Altec drivers with adapters on EV horns. Mantarays had great dispersion control but as they had a different acoustic center for horizontal versus vertcal dispersion, using them in multiples could be tricky. My Favorite horn was the 203B. My favorite drivers were the 802 and the 288. Though you guys have probably never seen one, Altec 950UHF was the best ring radiator I ever heard.
VolvoHeretic
Well-Known Member
I am going to fill the bells of my 511's with a mixture of foam bead for a bean bag chair from Kmart, and latex roofing coating from Menards. 
Kind of like Rice Krispy squares.
Kind of like Rice Krispy squares.streetwise
Active Member
nice interesting ideas ive read about the crossover idea and agree with that I might do that sooner than later as i want to replace the original crossover caps in these seeburg boxes. the 811s have a 806 driver I believe I will have to open them again soon, there with a 12" utah woofer. If I ever get a pair of 515 woofers I will build a cabinet asap to replace these cool but small for Altec boxes. I think im going to test out the modeling clay idea first as its a cheap idea to start. My fisher 400 cant go past 11oclcok or its painful to listen to these speakers. Funny the Snell JII speakers I have start to sound great at that point on the dial!
VolvoHeretic
Well-Known Member
Or maybe just leave them be and add a couple of small subs.
streetwise
Active Member
just an update here, I created a 32343 zobel network modified for the 806a being a 16 ohm driver. The overwhelming sound of the horn at high levels has mellowed out. The horn honk is gone now making things abit smoother
dc270
Now Off the Reservation
gdmoore28
Super Member
Excellent response! I'm pretty much convinced that what a number of people are describing as "ringing" is actually the VERY "shouty" mid-range response of a compression driver. Look at the unprocessed frequency response of almost all CDs and you will see that the midrange response is up to 12dB hotter than the 0dB point. So, of course it sounds like its ringing.
The answer here is to EQ the driver. The Altec equalization network is an excellent place to start. If I remember correctly, it brings the midrange response down about 6dB.
There's much more info on that here: http://www.audioheritage.org/vbulle...ok-at-my-new-babies-Altec-846Bs-w-EV-Tweeters!
Follow the links in that post and you will find a wealth of information on efforts to smooth the midrange response of compression drivers.
mhardy6647
Lunatic Member
does anyone use rope caulk any more?
It was all the rage -- a decade or two ago.
Tried it on the Cornies' MR hornies -- not sure anything could help those abominations, tho'
dampedcornyhornies by Mark Hardy, on Flickr
DSC_6386a by Mark Hardy, on Flickr
It was all the rage -- a decade or two ago.
Tried it on the Cornies' MR hornies -- not sure anything could help those abominations, tho'
dampedcornyhornies by Mark Hardy, on FlickrDSC_6386a by Mark Hardy, on Flickrbiscuithead
Me likes the eargasm retroplasm...
does anyone use rope caulk any more?
It was all the rage -- a decade or two ago.
Tried it on the Cornies' MR hornies -- not sure anything could help those abominations, tho'
+ 1 for rope caulk. I use a kind that you get at an HVAC supply store, it never dries out... kind of like duct seal.
mhardy6647
Lunatic Member
The only thing that will really help a Cornwall MR horn, though, is plastic explosive.
Similar threads
