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Altec 511B horns and Italian compression driver.
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Author:  mwhouston [ 25 Aug 2018, 00:09 ]
Post subject:  Altec 511B horns and Italian compression driver.

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Though my experience with horns in the past has been a miserable one it didn't dull my interest in them. In the past, at two hifi shows in Melbourne, I thought all the commercial horn based speakers I've heard, JBLs included weren't very good. And in a few domestic situations things didn't get any better.

Looking at Altecs on eBay they are usually pretty knocked around, being a speaker from the late 70s. They are about US$500 a pair with dubious compression drivers. It gets worse; shipping the buggers is usually about $100. But I was always open to any which may come along.

And along they did. In a nieighbouring state a pair of fully refurbished powder coated Altec 511Bs popped up at a reasonable price. Two bonus facts are the owner would share shipping ($40) and the were dodgy compression driver free. The drive will decide the sound and in the past all metal diaphragm drivers have sounded just wrong.

Welcome the Italin Faital Pro HF108R and their polymer based diaphragm and neodymium magnet driver. Fortunately there is a DJ store 30mins easy drive from me which sell a few different drivers. I bought their dearest hoping for the best sound possible. Bonus, they gave me slight discount. It's all up from here.

While waiting for the horns to arrive I modded a very good Xover to deliver -12db roll off for the woofer and -18db (2nd and 3rd order) for the horn. Xover point is 1600hz. The driver goes down to 1KhZ and will handle 60W! Some drivers will go down to 500 but to me a 1" metal diaphragm going 500hz seems just wrong. Also the HF108 is 106db effciency so a -17db pad was required. I had many pads from another two way system which I could use (and now have tweaked) to give about that suppression.

I had everything all setup and ready to go and within 30mins or so had the Altec 511Bs (designed to work down to 500hZ) up and going. This included fitting the new compression drivers which came with gaskets fitted and mounting bolts.

So Mark how do they sound. In a word "fabulous". Firstly the horns are pristine 100% condition and better than new with a thick, dense black powder coat. No dints or bits missing. I had about three hours of listening yesterday and played about 6 different genres of music and loved everything I heard. The horns sit on subby boxes I have had for some time which have a 12" poly cone with a fo of 25hZ tested. The trick is to not roll the horns in too early so voice bass etc is carried by the woofers. The woofers go down to 30hZ tested and are good to 4KhZ but nicely start to roll off at 2K. Rolling them off and into the horns at 1600hZ is just a perfect Xover point.

There is stacks of deep bass and the woofers are 92db efficient so now the system is 92db efficient. My 2W SE UL 6L6 power amp in combination with my new 4S preamp play plenty loud and a really sound good. Listening to test tones the system is good down to 40hZ with some output at 30hZ. I'm a happy man.
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Author:  mwhouston [ 25 Aug 2018, 00:55 ]
Post subject:  Re: Altec 511B horns and Italian compression driver.

A real change in direction for me and one I thought, up until this year, I would never go down. I must say now Im a convert. I'm going to have snug fitting boxes made for them.

Here are the horns with new Italian Faital HF108R compression drivers mounted.
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Author:  gofar99 [ 25 Aug 2018, 15:18 ]
Post subject:  Re: Altec 511B horns and Italian compression driver.

Hi Mark, Welcome to the world of 1975. I use an Altec 416 as a woofer and a Radian 475PB on a Seas 30cm wave guide in the 200 L vintage Altec Lansing Magnificents. I used a 12 db low and 12 db high crossover at 1750 with a pad down on the 475 of 14 db. I suspect they sound a lot like your set up. The biggest issue they like to play in a really big room. Mine is a bit small at 72 cubic meters. 200-300 would be far better.

Good listening
Bruce

Author:  mwhouston [ 25 Aug 2018, 16:56 ]
Post subject:  Re: Altec 511B horns and Italian compression driver.

From the horns what do you think of the mid range sound? Voices etc. How do you think they compare to cone similars.

Author:  mwhouston [ 31 Aug 2018, 08:59 ]
Post subject:  Re: Altec 511B horns and Italian compression driver.

A friend brought over some CDs in which some tracks have thundering synthesised deep bass. Mine bass boxes, powered by the 6L6 SE UL 2W amp, produced so such bass. But he did feel on a number of tracks the bass was good. Also he felt that the mids and treble was a little dull.

A few years back I made a pair of Class D monoblocks based on the hifimediy DIY T3 150W (into 8ohms) modules; http://retro-thermionic.blogspot.com/2016/11/tutu-150w-tripath-class-d-monoblocks.html

I rang the guy who bought them almost the week I made them to ask if I could buy them back to run my Altecs and drive more bass from the bass boxes. He was more than happy to swap them out for a Pass BoZ preamp. I was more than happy with the deal.

Now I have good bass output to 30hZ with some output at 25. The biggest delight is the Altec 511B horns with Failal drivers sound even better. I was worried that the horns could get screechy with the extreme detail the Class Ds are cable of. It's almost the opposite. The mids are natural, clean and very (but not overly) detailed. Treble now is bright and airy with no unatural or over emphasised sibilance. Imaging has lifted but not hard etched. It's like a combo made in heaven.

Not sure you would get the same result with horns which is a driver with a metal diaphragm. The polymer diaphramed Faital drivers have a more natural presentation than the metal diaphramed drivers I have heard in the past. Still shocked that the combo worked out so well.

Author:  mwhouston [ 02 Sep 2018, 18:39 ]
Post subject:  Re: Altec 511B horns and Italian compression driver.

Not sure I posted this. These are old Xovers from the Beymas Xing at 1600hZ. 2nd order on the woofer and 3rd order on the horn. Caps are proper 100V Xover caps, metalised poly, apart from the one across the woofer - 100V polyester.

One inductor was a bit small, so I back wound a slightly larger one on a ferrite rod I had wound for another project and added it. The Xover sounds perfect. The horns go down to 1K but they suggest no lower than 1.3K with a second order Xover. So Xing the horns at 1.6K with with 3rd order is even better.
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