Installing Mike's Altec 511B horns

[Q-Man]

Where do I start? It was a 9 hour day and and can't write half of what I want to.

Mike's main speakers are LaScalas as most of you know. The LaScalas are stock except for the ALK network upgrade ,an improvement we discussed in a past post. Our goal was to install the 511B horns and see if there is any truth to the opinion that the K-400 horn is worth replacing in the LaScala and Klipschorn.

Mike bought a pair of 511B horns and to replace the 400 horn , because of some of the board members opinions. I also brought over a Cobreflex horn with a University T-30 driver and an Altec 805B ten cell horn with an Altec 288-16K driver to add to the comparision.

I brought these drivers, but I really wanted to hear the differences in the horns with the K-55M driver. For most of the comparing we used Mike's Scott tube amp, because it was easier to run the same mono signal to both of the speakers and use its balance knob to switch back and forth between the horns. We also used his home theater Denon rec. and Acurus power amp. combo. for some of the listening.

We drilled the 511B horns to fit the throat adapter for the K-55M and then got started. We put one 511 on top of one LaScala and screwed in the K-55. We left the other LaScala as is with the 400 & 55. The first thing that you notice is that the 511 is louder then the 400. Then you begin to tell that the 511 it is a little cleaner or more open. The 400 is more nazal and dull sounding. With some insturments like the acoustic guitar the horns sounded the same. I thought the 511 began to sing when listening to female voices. Then the saxaphone sounded so much better with the 511. By the way, all are comparisions were done at a SPL of 104db in Mike's room. That just happens to be the level Mike listens to all his music and movies at. So, there wasn't much we were missing at that volume. Everything seemed clear and crisp with eather horn.

I then disconected the tweeters and woofers from both LaScalas. I wanted to isolate the midrange horns and get a little more serious. It has always bothered me that some of you use a horn with a 500Hz cut off frequency with a 400Hz crossover point. We put in Stereophiles test CD and started with a 315Hz tone and worked are way up to 8000Hz. We wrote down the db levels for both horns for the various frequencies. I don't have them here, so I'm doing this from memory.

The 511 was indeed louder, it is 3db louder then the 400 at most of the tones. Both horns were within (+) or (-) 1 or 2 db from 500 Hz to 4000 Hz. Both horn were about 2db down at 400 Hz. I guess I was wrong about this horn,it's as good as the 400 horn at 400Hz. The 511 and 400 are also equal at 5000Hz. It's around 6000Hz that now concerns me. At 6000 the 400 begins to peak while the 511 begins to fall. This troubles me a little because the network crossover is at 6000Hz. Are we missing too much with a 6000 Hz dip in the 511?

Or might this be an inprovement, since this is where the tweeter takes over?

Mabey a tap setting adjustment on the ALK network is needed, since the 511 is 3db louder, maybe not , I kind of liked it that way Time will tell.I tend to vote for the 511 change.

Next we ran in problems, we lost the left channel when using the Scott and Denon/Acurous combination. It's the speaker, right? It's too much of a coincidence the both amps left channel would fail. I began checking out AL's network, but it was fine so that was a waste of time. To make a long story short and I mean a long story, because it took three hours of switching cables, speaker wires and the Denon menu settings. We eventually found the problems, we had a bad speaker wire on the left channel of the Scott, and we blew the left channel of the Acurous power amp, and I don't mean just the fuse. I told Mike that it was pay back time. If you remember we blew up my Sunfire Signature during Mikes first visit to my house.

We left the Acurous out of the system which was connected to the Denons pre-outs, and just used the Denon.

Now it was time to burst Mikes bubble again. I hooked up the Cobreflex horn to the K-55M that we were using on the 400. Now we were comparing the Cobreflex horn with the 511. I knew that I liked the cobreflex T-30 combo, but I never tried this horn with the K-55. I also never heard the 511 before so I didn't know what to expect. Well. Mike had a few choice words for me that I can't repeat here, because the Cobreflex did to the 511 what the 511 did to the 400.

My conclusion thus far is for anyone seeking a change to use the Cobreflex.

I will continue this a little later my two fingers are tired. I do need to talk about the 805b and the 288-16k, plus a few other things yet.

[TBrennan]

Q-Man---It would be interesting to run response curves off axis. I'm thinking the stronger response of the K-400 around 6khz is because the directivity is collapsing, thus raising the response on axis. I'm thinking that while the 511 collapes in the vertical as frequency rises the K-400 is collapsing both vertically and horizontally.

My own testing, with an RTA and calibrated Panasonic mic, shows that both JBL and Altec 1" drivers have flat response out to 16khz on the 511. But the same JBL 2427 that runs to 16khz on a 511 drops dead at 8khz on the Altec 1005 10 cell horn, a horn with constant-directivity.

You know, that Cobra-Flex is a re-entrant horn, it's not supposed to sound good! :-)

Thanks for an interesting post.

www.chicagohornspeakerclub.org

[Mike Lindsey]

Thanks for the review, Q. It was indeed a long day but we learned a lot in the process. I have already stated my opinion on the 511B versus the K400 in the other 511B thread started by Al K. Here is what I said on the matter:

Not only is there wider dispersion but there is more clarity and separation as well with the 511B. It's not so evident in the acoustic instruments (piano, guitar, etc), but very noticeable with vocals and horns (sax and trumpet). I also like the fact that the horn sits about 10-12 inches higher (resting on top of the La Scala's) than the K-400, and is more at ear level. Believe it or not, this makes a very noticeable difference. The 511B is also about 3db louder from 400 to 5khz. I have not adjusted the tap settings on the ALK's yet because I kind of like the overall sound.

After spending another day listening to them, I can honestly say they are dramatically better than the K400. The Scott 299, Dual CS-5000/Shure V15V-MR, and La Scala's w/ALK's and Altec 511B's is purely magical. They just sound so good at the moment that it's hard to believe they can get better. Tom Brennan says the Altec 902-8A driver will better the K55 and that may be my next upgrade.

Q-Man is right regarding the University Cobraflex. I don't know what it is about that horn but it is smoother and louder than the 511B. We played it with the K55 and University T-30 driver, and I actually preferred it with the K55. Even though the T-30 had more output it seemed to be a little harsher than the K55. The other nice thing about the Cobraflex is you don't need a driver adapter, since the K55 screws right on.

Even though I preferred the Cobraflex to the 511B, I think I am going to stick with the 511B because I like it better aesthetically. I talked to Q about possibly building an upper cabinet to house the 511B (ala the Khorn) using plywood and birch veneer, and then staining them to match the La Scala cabinets. He said he would draw up some designs when he had a chance.

As for the Altec 805B w/288-16k driver (the biggest driver I have ever seen), I will wait for Q to post before I add my comments. BTW Q, isn't that a 8 cell horn? I thought TB is the one with the 10 cell horn. I am also hoping Q comments on the Eagles HFO in DTS as well as some of the DVD-A discs we played on my system.

As Q-Man mentioned, we lost about 3 hours of demo time due to the left channel going out simultaneously on both systems but for different reasons. On the Scott it was a bad speaker cable. On the Acurus it seems to be a bad channel (number 2). I am not sure if it is the pre-out on the Denon or the amp itself on the Acurus (I suspect the Acurus). I checked the fuse on the Acurus and it is fine. I will post this problem on the Acurus board and hopefully Steve P or somebody has an answer.

Anyway, it was a great day and I'm looking forward to our next get together...

Mike

[Stovebolt6]

Mike sounds like you had a fun day!

I have a question regarding the Altec 511b Horn. The Heritage line uses horns that follow an exponential curve. In the new products Klipsch uses the tractrix curve for the horns. The idea here is that the tractrix curve provides a closer representation of the natural expansion of the sound wave. My question is what type of curve does the Altec 511b use? In your testing did you take any off-axis measurements?

[Mike Lindsey]

DB,

I'm not sure about the differences between a exponential and tractrix horn. I guess I should but I really don't know. Tom Brennan could certainly answer this question and may be able to explain the two as well.

As for the off-axis measurements, we didn't get them. But let me say this... it almost sounds as good in my hallway as it does in the middle of the room. Previously, I had a very small sweet spot and needed to be sitting in it to get the best sound. Now I can almost wander around the whole room and it still sounds better than the K400 in the sweet spot.

When I get better, maybe I'll do some off-axis measurements and then post them to the board...

Mike

[Q-Man]

I liked the wider dispersion of the 511 and Corbreflex. It broadens the sweet spot. I think Paul liked the narrower dispersion of the 400 because it helps eliminate room reflections. Paul obviously knows much more about this then I do, so hopefully the wider dispersion won't hurt much. It may depend on the room. I noticed the new Jubilee uses a much larger horn and has a wider dispersion patern. Maybe Pauls views changed durning the developement of the Jubilee.

Next we hooked up the Altec 805B(eight cell horn, I stand corrected)and the 288-16K driver. We compared this combo with the 511. The combo is sweet and is the best sounding of what we tried, but we wondered if it is worth the money? The Cobreflex w/the 55 was close sounding to the 288/805. You can pick up a pair of Cobreflex horns on ebay for around $100.00 and just screw in the 55. For the Altec 805B & 288 drivers you can expect to pay about $450.00 to $800.00 on ebay. We didn't feel that the slight difference between the Cobreflex & the 288/805 combo is worth it. May have to try this again.For eather of these mods you will probably need AL's network so you will be able to lower the volume of the midrange by adjusting the tap settings. Both of these horns are about 5 to 6db louder then the 400.

The 511 is 3db louder and I think you can leave AL's network alone and even use the Klipsch networks with it. I don't think it sounded bad this way. Mike will have to let us know after he lives with it a while.

Again, I'll add more when I get home tonight. I do want to talk about

DVD Audio and Mikes SVS 2039.

[Colin]

sound slike fun: wish I was there!

[Al Klappenberger]

Hi Guys,

Very interesting comparisons!

I changed out the 511 horns in my Belles for 811s a few weeks ago. If anybody is trying to figure how to fit a 511 in a Belle or La Scala, use 811s instead. The two sound virtually the same to me.

One small point: If you are comparing squawker horns using my network with the tweeter disconnected, put an 8 Ohm load resistoer in it's place. The response of the network out the squawker rolls off very poorly beween 4000 and 6000 Hz with the tweeter open. It also generates a huge notch at about 7600 Hz. The rejection "arcs" to a minimum of 10 dB the up again at high frequency. This could influence your judgement if you have a wide range driver on the horn.

AL K.

Correction:

Major point! The response with the tweeter disconnected that I mentioned above was done by computer analysis. When I did it, I was assuming an 8 Ohm source impedance. Most amps have a source impedance closer to 0.1 Ohm. In this situation the squawker channel response is terrable! You MUST terminate the tweeter connections with an 8 or 10 Ohm resistor or the squawker will probably sound like crap!

[Q-Man]

We didn't do any off axis listening. We were sitting about 12 feet in front of the speakers holding an SPL meter in front of us. The speakers were aimed right at us. I have to admit that there was more we could have done. Now that I think about some of the things we rushed on, I wish we had more time to do more.

Colin,

I'm sorry. Next time we get together we'll let you know. But, in order to be initiated into this

club you must bring a piece of your equipment that we can distroy.

You also have to give a listen to DVD Audio. I know that your a two channel man , but this will knock your socks off.

As you may know, when I listen to CDs I always use a dsp setting and have all my speakers going. Well this DVD Audio does what I've always tried to achieve and more.

I have all the necessary equipment for DVD-A, but the DVD -A player. My DVD player is old and doesn't even play DTS. That was also nice to listen to. After Mikes demo, I have to seek one out.

My son goes to college near Mike, and I left Mike a tv to give to my son. I told my son that when he goes to Mikes to pick up the tv that he has to give DVD Audio a listen.

[Q-Man]

I also had my first SVS audition at Mike's house.

Every time Mike comes over to my house he comments

on how he can't generate the amount of bass that I have, even in his smaller room. Some of it is the difference between the Klipschorn and the LaScalas, but I think it has a lot to do with his SVS 2039 and my Sunfire Signature. This particular SVS is no match for the Signature. The 2039 can't keep up with his LaScalas. I was wondering if a more powerfull amp would help? The amp from SVS starts clipping before you can get the 2039 loud enought. Mike you were talking about getting another 2039. That may give you another 6db, but I don't think that that would be enought. Two subs in that room might also cancel each other out do to standing waves. I would read up on the Ultras and try to figure out how much more one of those would give you. Any SVS owners have any comments on this?

Here is an idea. Sell your SVS to a non Klipschorn or LaScala user and buy my Signature. That SVS would be fine for another type of speaker. Then I would buy a Velodyne HGS-18. The Sunfire would fit mush nicer in your room.

[mungkiman]

Mike,

Glad to hear you enjoyed playing around with different horn/driver combos. Sorry to hear about your neck and upcoming surgery. Good luck with that, and get better fast. Sincerely,

Chris

[TBrennan]

Stevebolt---The 511 horn is straight-sided on the sides and has an exponential curve on it's top and bottom surfaces. The straight sides determine and hold the horizontal dispersion. The exponential curve narrows the vertical dispersion as frequency rises. This type of horn is known as a "radial" horn because the 2 straight sides can be defined as 2 radii of a circle seperated by an angle, an angle which determines horizontal dispersion. JBL and EV have also made such horns. Such horns have been made with angles of 40, 60, 90 and 120 degrees. Altec called them "sectoral" horns because they resemble a sector removed from a circle.

Tractrix horns supposedly provide a better "launch" of the wave away from the horn with less reflections back down the horn. I'm thinking this advantage is more theoretical than real. I have Edgar wooden "saladbowl" tractrix horns and after using them for awhile I went back to the 511s. This is a matter of preference. Opinion in our club is split, some guys think my system sounded better with the Edgars and some with the Altecs. Both sound excellent.

www.chicagohornspeakerclub.org

[mungkiman]

Tom,

What is a re-entrant horn? Thanks,

Chris

[justin_tx_16]

I THINK it is a speaker that has the driver pointed into the horn... a bull horn or megaphone is a re-entrant horn.

[Mike Lindsey]

Q,

I am in total agreement about the Altec 805B versus the Cobraflex. As close as they were in sound, it would not be worth it dish out the extra ducats for the 805B's. Plus, you can use the K55's to drive the Cobraflex horns.

I think I have to agree with you as well regarding my SVS 20-39CSi/Samson S700 combo that I am using for HT and multi-channel music (DVD-A, DTS, DD5.1). It does not quite put out the output that is necessary for the La Scala's. On some sources I have to dial it down because my amp starts to clip at certain volumes, even though there is plenty left in the La Scala's.

The easiest thing would be to add another 20-39CS+ but they wouldn't be next to one another. The other one would have to stand on the other side of the fireplace. Yes, it would add another 6db but it also may cause problems with cancelling one another out. As much as I like HornEd's stacked Ultra's, I just don't think that would be the answer for me because I can't put them back in the corner where I think they should go.

Therefore, I think I will try and sell the SVS/Samson and look into something else that fits my room, as well as puts out more output and is just as clean as the SVS. I will do some reading on the Sunfire Signature, Velodyne HGS-18, Rel Strata III and RSW-15 and get back to you...

Mike

[Q-Man]

Mike,

I've been doing a litle thinking about some changes the last couple of days.

I might sell off the stuff that I don't use anymore, and some that i never used, and some stuff that I've been saving for the kids.

I'm thinking of selling,

One pair of LaScalas

Two pairs of K-400 horns

Sunfire Signature sub

KG5.5 drivers and networks for a pair of Kg5.5(all brand new still in the boxes).

One KLF-C7

Some LaScala AL networks, and maybe more.

The sub will be my hardest decision, I really like it, and it might not be worth going to something elce.

How are you finding the volume of those 511s. Do you think you need to change the tap setting?

I just heard that your other piece of glass is ready to be picked up.

[Mike Lindsey]

Hey Q,

I might be interested in another pair of La Scala's. Is the Raw Birch pair available? I'm not sure about the Sub yet as I want to do some reading first. I may sell my AL networks as well, but it might be worth it to keep them too...

Mike

[Mallette]

Pirate walks into a bar with a horn sticking out of his pants. Bartender sez "Hey, Bluebeard, isn't that an Altec 511B sticking out of your pants?" Pirate sez "ARGH, it's driven' me nuts."

Dave

[Q-Man]

Mike,

My selling of this stuff is still in the planing stage. I may change out the 400's to the cobreflex. If I do I will build a LaScala for the center channel instead of modifying the existing one. This would put a pair of them in the closet instead of just the mate to my center channel. So I might sell them. Yes it would be the raw pair. I figure I would offer them raw at one price and finished at the buyers preference for another. I'v been looking at the K-Horns and false corners tonight to see what it will take to build new tops. Before I do this I want to give the cobreflex another listen to.

You didn't answer my 511B question,or is it too soon to tell?

I'll keep you posted on what I'm doing. I'll email or call you. I don't want to say what I may be selling here untill I'm sure. When I decide I'll offer most of it here first,with prices, before going to ebay. I got a few people excited by saying what I might sell.

[Mike Lindsey]

Q,

I am loving the 511B's! I can't get over how good this system sounds at the moment. It is so clear, with more separation than I have ever heard. Vocals and horns are incredible! Suffice it to say, I am very happy.

Let me know how your's sounds when you hook those Cobraflex's up to your Khorns.

Just so you know, I would be interested in the La Scala's, depending on the price of course.

Mike