Altec 511b horn and K55V driver combo ??

[Al Klappenberger]

Hi guys,

Quite a few people have suggested replacing the K400 horn in their Khorns

with an Altec 511B. The problem has been that the K55 driver will not simply

screw into the Altec mounting flange. The question becomes, what effect will

simply jury-rigging it to the flange have on the response. To answer this, I

dug out one of the temporary rigs that I used while I was waiting for a set

of JBL drivers that I could make fit properly to the flange. I ran frequency

response curves using a late model K55V (with the two piece phase plug and

solder terminals) and an Altec 511B using this rig (the black curve). I also

ran a curve using the same driver on one of the K501 metal squawker horns

from my Belle Klipsch. That's the red curve. This is also a 500 Hz horn. The

nasty looking glitch at about 600 Hz on the K501 is probably due to the fact

that it was simply sitting on a chair without having the benefit of the wood

mounting flange (baffle) that it should have to perform properly, but I don't

really know. I am sure that it is not real though. The combination of the K55

and the 511b horn looks good enough

to get away with the 400 Hz crossover needed to work with the Khorn woofer.

I should also mention that these curves where NOT done in a anechoic chamber

and partly represent the frequency response of my office!

The adapter is simply a piece of 5/8 inch particle board with the K55 ram-

threaded into a hole. It is flush against the horn flange inside. A

commercially made adapter like this is available.

Al K.

This message has been edited by Al Klappenberger on 09-06-2002 at 02:58 PM

[Hardhead]

Al--

How did the performance of the 511B/JBL driver combination compare to the 511B/K-55-V?

[Stig]

AL,

I jumped on the bandwagon and got some 511B's off ebay

last week. They have not arrived yet and I am leaving for Reno-Vegas for a week.

Thanks for posting that picture of your mounting scheme. I will do the exact same thing.

Now I can spend my time playing and not wondering how I'm going to mount those drivers.

Thanks,

Stig

[Al Klappenberger]

Hardhead

How do they sound? Pretty good! When I made the change, I also mounted the T-35 tweeter verticaly. The results were far better disperson. I think the 511 is simply a better horn.

Al K.

[95yellovett]

I have a pair of Voice of the Theatre's with the

511b\808-8a horns and love them.I will try and

upload a picture.

They are excellant drivers.

95yellovett

[soundog]

Parts express makes an adapter as does atlas. You will have to redrill the holes on the back of the 511B - the adapter needs 3 the 511 only has two. They are very easy to drill. The 511 sounds more open (wider dispersion}, a little clear and smoother than the K400. You may have to dampen it and mount it on a board to tweek it. The combo brings out the best in the K55 driver. The 500 Hz lower end rating of the 511 and the 400 Hz lower end rating of the K55 seem to work fine. As Gil points out the difference between 400 Hz and 500Hz is slight and I can not hear any loss between 400 and 500. In short the 511b offers a slight but noticable improvement over the K400.

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Soundog's HT Systems

[edwardre]

To me, the difference is considerably more than "slight but noticable". I will concede that if you were previously sitting in the K400's 'sweet spot', the 511 could be a slight but noticeable difference. However, the real charm of this horn is it's ability to broaden the 'sweet spot' to room filling, glorious proportions. I have replaced the K400 in my FR & FL Khorns, as well as my front center and rear center Belles and the result is tremendous. Every seat in the room is filled with grandiose sound, a feat that I would wager to be simply impossible with the tight 'particle-beam' construction of the original straight horn. If I could figure out a way to replace the straight horns in my surround R&L Cornwalls with 511's that would appease the WAF, I would without hesitation do so as these still produce highly directional sound. I suppose that this would be a moot point if you had a 60' x 60' room, but in a "normal" home listening environment, IMHO, you cannot beat the dispersive qualities of the 511B (or A). For a center speaker, this is especially critical unless you have but one seat in the room staring down the throat of the K400. The increased clarity and better overall sound of the 511 is just an added benefit.....

Al and others....is the hole size of the adapter(s) you are using the same size as the opening to the 511? Or is it smaller?

------------------

Ed

[Mike Lindsey]

Edward,

Are you also using the K-55 driver on the 511's? Do you just have the horn sitting on top of your Khorn and Belle cabinets or did you modify the cabinets? Do you have pictures?

Thanks,

Mike

[soundog]

Ed-

I agree - the improvement in dispersion is the most dramatic change when using the 511s. I was particularily impressed with the effect on the center channel where I use a 511 presently. I didn't notice enough of a change in my two Khorns to tear apart the cabnets. Perhaps the fact that I had the two 511s on top of the Khorns which are only 12' apart and angled directly at my sweet spot seat resulted in my not noticing the improved dispersion characteristics of the 511s when used with the corner horns vs the center channel where the 511 is mounted above the TV monitor and angled down. I plan to get a couple more 511s and do some additional experimenting.

The adaptors from parts express have the same size hole as the 511 and the flange matches the flange on the 511 as well.

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Soundog's HT Systems

[mungkiman]

Some of you may also be interested in trying University Cobreflex horns. Personally, I like the sound of the Cobreflex better than the 511B when mated to K-55 drivers. The dispersion is greater than the 511B too. 120 degrees horizontal and 50 degrees vertical for the University, and 90 degrees H by 40 degrees V for the 511B. The design of the University incorporates a 27" exponentially-flared air column, allowing crossover as low as 350 cps. I think this should make up for what is missing in the 400-500 Hz range. The folded design also allows for installation in smaller cabinets, and may help the WAF for some of you. Take care all,

Chris

P.S. No flange to threaded adapter needed.

This message has been edited by mungkiman on 09-13-2002 at 06:29 PM

[Al Klappenberger]

Here's a top view of the particle board rig..

I agree with Edwardre. The 511 horn is a big improvement. It think it did more than when I put the big JBL drivers on in place of the K55V (on the 511 horn that is). I was comparing it with the Belle Klipsch 501 horn.

Al K.

[Mike Lindsey]

Is anybody using the ALtec 808-8A with the 511B horn? I am interested in this combination with the ALK crossover on my La Scala's...

Mike

[edwardre]

Mike, currently I have my 511b's mated to SAHF's. The reason being is that my Khorns are 1954's that came with the SAHF originally and I wanted to match tonally the center with the flanking Khorns to create a timbre-matched soundstage. BTW - IMHO....the SAHF sounds better than the K55 through the 511b...clearer and more robust.

The 511b's are in the top cabinet in both Khorns as well as the Belle. The Khorns weren't a problem as they are the original KA model.....about 2.75" narrower than the KB, KC, or KD as well as having a taller upper cabinet. Removing the 1" (or so) top and bottom mounting flange on the output side of the 511 afforded plenty of room to mount the horn out of site. The Belle was another story. After removing the top and bottom flange, there was still about 1" too much 'horn' to fit into the upper cabinet. I did not want to disrupt the original look of the Belle, not did I want to defile it in any way. The criteria I set for myself was exactly that....had to look original and had to be 100% reversable.

The first thing I did was to remove and replace the 'bottom of the top cabinet' with a fresh piece of oak veneer (walnut wasn't available locally to me at the time). Setting the original piece aside in the closet, I then cutout exactly the dimensions of the 511, exactly where I wanted it to sit:

Next, I stained to match and mounted the 'new' cabinet base piece:

Next, I lowered the 511 into it's new home. The 'collar' seperating the upper and lower sections, in tandem with the space gained from the thickness of the wood itself, created just enough room to fit the horn in. At this time I also mounted the tweeter (4401) as well as the network:

From here, with the lion's share of the modifications completed, I attached the original sides and top:

Next up was to replace the original grille assembly with one that was completely open to take advantage of the sectoral horn and the 'wraparound' grille style of the Belle. I framed this up with strips of 1/2" plywood assembled with a series of little 'L' and 'T' brackets. It was amazingly stout:

Then I painted it flat black, stretched fresh Klipsch grillecloth over it, and attached it. The result is a Belle that looks identical to the original one that can be restored to the original factory condition with about an hour's worth of work:

You can also see that the Khorns have a taller upper cabinet than current build models. That is if my attempt at inserting the pictures came through. If not, I will follow up with another post with pictures attached 'normally'.

Chris - I've not tried the Cobraflex horns, but do have a Cobra12 horn. This thing looks almost identical to the 511b, bit is 'cheap' and thin. However, it sounds great. Looked to me like the Cobraflex was seperated in the middle and was in reality, two seperate horns. How does this affect the sound if you are directly in front? Also, can you mount any driver? Did you mount those SAHF's in Cobraflexs?

------------------

Ed

[TBrennan]

Mike Lindsey---The 808 is not the preferred driver for sound quality; it was designed for improved power handling over the 802 and was used in speakers intended as small rock band PAs. It has less extended highs than the 802, 806, 902 and 909.

The 808 is identical to the 802 except for the diaphragm, for improved highs use 802 diaphrgms or Radian replacement diaphragms.

I've used 802s and 806s on 511Bs, also 808s and 808s with Radians, have also used JBL 2410s and 2420s on 511Bs. Right now I'm using 908s with Radians on them. The best sounding Altec 1" drivers are the ferrite magnet 900 series with the "tangerine" phase plug.

Now that some of you guys are getting hep to the excellence of the 511B it's but a short step to a realization of the excellence of a full VOT system. Get rid of those bullhorn mid drivers and that scratchy EV tweeter and replace with a 902, ditch that folded horn with it's cheap woofer and get 515s in 825 cabinets and hear how good bass and midrange can really sound. :-) My opinion of course.

www.chicagohornspeakerclub.org

[rune]

Tommy,

when you mention 515s,have you heard the 3154 which is supposed to be a more extended sounding driver than 515?It's supposed to have freq responce 30-2000Hz...

The guy who has offered me some 816 has several basses for these.He has 1 515LF 1 LFE 2 E's and 2 3154...

Which would you recomend?

Regards,

Rune

[Mike Lindsey]

Tom,

Thanks for the reply. Unfortunately, I am going to stick with my La Scala basshorns for a while but I would really like to hear what they sound like with the 511B horn and a 500hz driver. Are you saying the 902 is the one to use here? Is it also an 8ohm driver?

After hearing Q-Man's University Classic (which had all University horns and drivers), I realize there are better midrange horn/drivers out there than the Klipsch K-55/K-400 combination. And after reading all the positive comments regarding the 511B's, I would like to see what all the fuss is about...

Thanks again,

Mike

Edit: BTW Edward, that is very nice work you did on your Khorns and Belle...

This message has been edited by Mike Lindsey on 09-14-2002 at 07:23 AM

[Q-Man]

Mike,

I got your email and saw this post. I never should have let you get those LaScalas. Now you caught the tweaking fevor and there is no known cure for it.

Tell you what, I'll plan a trip over. I'll bring a Cobreflex horn and we'll try it with the K-55. I'm like

Chris, and think it's better then the 511B for Klipschorns and LaScalas. I'll also bring an Altec 805B horn and the 288 driver and let you hear that combo.

Q.

------------------

Q-Man

[Al Klappenberger]

Hi guys,

The mods Ed made to get a 511 horn into a Belle are very similar to what I did to my three Belles (click on the little house icon below). I used 511s in my flanks and and 811b horn in the middle. The 811 fits a lot nicer into the Belle. It doesn't stick the driver out the back. I will be converting the 511s to 811s in the flank speakers very soon. You would definitely need the 511 in a Khorn though.

The Belle and LaScala woofer horn will go nicely up 700 Hz and gets along with the 811 horn nicely. I am crossing over at 700 Hz with an extreme slope crossover (120 db / octave) though. This lets me go lower than the 800 Hz the 811 was intended for. I still think it work ok with the stock Klipsch networks.

Al K.

[mungkiman]

Ed,

First, excellent work! Great post for the DIY's in the group.

I tested (listened to) the Cobreflex horns with the SAHF drivers this morning, as well as with K-55-V drivers. I like the K-55/Cobreflex combo better than the K-55/511B pairing. However, I like the SAHF/511B better than the SAHF/Cobreflex. I also like the SAHF/511B better than the K-55/Cobreflex. These are only my opinions.

The opening of my adapters is the same size as the throat of the 511B. I am using the rubber washers that came out of my K400 horns though, restricting the opening somewhat. I don't know if this makes a difference (bug screen opening size) or not. Perhaps someone knowledgeable will speak more on this.

The University horns are indeed two separate horns with what must be 60 degrees of horizontal dispersion apiece. They sound great with separation only very close to the horn mouth. The threads are the same as the K-55 and similiar drivers.

I too, think some of you may like the University 4401 tweeters with your 511B or Cobreflex horns. Again just my opinion, but I like the sound.

Chris

This message has been edited by mungkiman on 09-14-2002 at 01:03 PM

[Mike Lindsey]

quote:

---

Originally posted by Q-Man:

Mike,

I got your email and saw this post. I never should have let you get those LaScalas. Now you caught the tweaking fevor and there is no known cure for it.

Tell you what, I'll plan a trip over. I'll bring a Cobreflex horn and we'll try it with the K-55. I'm like

Chris, and think it's better then the 511B for Klipschorns and LaScalas. I'll also bring an Altec 805B horn and the 288 driver and let you hear that combo.

Q.

---

Yeah... I'm blaming you from now on.

I think it's great that we have people on this board who have experimented with all these speakers and can add their thoughts on what works and what doesn't. But even better than that is to have someone like Q-Man, who only lives 45 minutes away and owns most of this equipment himself. I look forward to just going over to his house and listening to the different combinations.

Q - Is the Cobraflex what we listened to on your University Classics? Let me know when you think you can make it to my house. We'll make an evening out of it and I'll provide the wine. It probably won't be from the mid 80's however.

Mike