Al Klappenberger

Edwarde, Several of the pictures should help explain how I got the 511B in the top of the Belle. I might point out that I did not modify any parts of the Belle whatsoever. I can restore them to factory-perfect Belles in about an hour. The secret is the raisers on each side made of poplar cabinet wood. I screwed 3/4 inch hardwood square dowels around 3 sides of each raiser and simply screwed them right under the high frequency compartment top. They are made exactly like the ones already there (the sides). The top two holes in the front were used to attach cross boards to hold the top of the 511 horn flange. I used the screws that came out of the same holes. Another cross board supports the bottom of the horn. It is fastened to the new raisers using the other screw. The bottom hole in the front holds the grill cloth frame using a screw from the back. The the other picture shows the grill cloth frame in place before I painted it black. The K77 tweeter is mounted inside the frame for use temporarily until I can get a two-way crossover designed. It is mounted vertically. You can view the pictures at: http://www.web-span.com/alk/dload Al K

John, Did you see what I did to my Belles? Take a look at the "winter and spring project" here in Odds and Mods section. I am putting an Altec 511B with JBL 2421 drivers on mine. Right now I am running it 3 way with the K77 tweeter until I can get a crossover built for 700 Hz. My measurements show the Belle woofer extends nicely up to 700 Hz. The Altec 511B will go down to 500. The JBL driver starts to loose power handeling capability below 800, so I am compromising at 700. With the tweeter vertical it sound super. AL K. This message has been edited by Al Klappenberger on 06-08-2001 at 11:37 AM

JD, Sorry I didn't see you question aboutthe bass till this morning! The Cornwall center definitely extended the bass down. I always had a problem getting the phasing right though. I was never sure if it was better in phase or out of phase! It's a moot point now though. The LF-10 sub is set to cut in at 100 Hz and it takes over from all three speakers. Al K.

J.D, The Belle grill for the high end is just cloth. You could replace it with anything. Sorry the picture is not focused right, but you get the idea! Al K.

Shock. I think the reason Klipsch mounts the tweetera horizontally is stricticly business related. To vertical mount it (like with the old Cornwall) you would then have a left and a right speaker to make in pairs. What a mess that would make for the production department! I heard that was exactly what happend with the early Cornwall (grapevine). AL K.

Mark, I am about to see what you mean.. Take a look at my latest post here (Ods & Mods). I have two JBL 2420s with 2421 diaphragms on the way. My Belles have been modified to accept them. Al K.

Clint, Yep.. What we are dong could be consdred "Heresy", but there is some good logic involved.. The latest pictures show the stage I am at right now.. I still have to make a fram for the grill cloth covering (you know.. wift acceptance factor). The Altec horn has the Klipsch K55v jurey riged on them and the K77 tweeter is hung by a single screw. It will go when I get the JBL drivers. I will say this so far: Vertical is definitely the way to mout the K77 tweeter. The dispersion is much better. I almost could do away with the center fill Cornwall! Al K.

jweed, Very interesting! I just started today to do something similar to by Belles. I am going to try two-way using Altec 511B horns with JBL 2421 drivers. I know that two-way is what PWK wanted, it just wasn't possible with the limits he had to contend with. The pictures are just to document things as I go along. It's a long way from done! Al K.

Hi Guys, The K77 tweeter IS an ElectroVoice T-35. There is noting wrong with the "M" version. A lot of people will tell you Alnico is wonderful, but remember, it's just a magnet! Fact is, the "M" was upgraded in addition to the magnet change. The "M" is the better tweeter. I have tested both. The K79 has lower sensitivity then the K77. That is why it is not compatible with my Cornwall network design. AL K.

Chris, Try this: http://www.northcreekmusic.com/801web.html Pete, The Cornwall makes an excellent center speaker so long as you don't have a TV set there! It's too big to put on top of a TV, and not big enough to set the TV on top of it! Al K.

Chris, Your's right. I make enough money form them to make building them worth it, but that's all. Take a look at North Creek Music's upgrade for B&W speakers. They charge nearly 3 times my price for a set! It's my way of seeing to it nobody else will steal my design and undercut my price. They would starve doing it! AL K.

Thanks Allan! AL K This message has been edited by Al Klappenberger on 05-30-2001 at 07:57 PM

Hi guys, I didn't put Chris up to this! Honist! AL K.

Hi Guys, John has a good idea. A dealers used "stock" is usually limited but they price stuff by some "book value" that is usually very low compared to what it's actually worth. I tried to sell an MCD7000 once and asked a dealer to dipslay it. The price he said I had to ask for it was totally unreasonable. Al K.

Jim, Send me an email and I'll give you a price quote. alk@alkeng.com Al K

djk, Yes, I am aware of the lower power limits on the JBL drivers. I untimatly plan to move the crossover up to 700 Hz with high order network and go 2 way on a different horn. The screw-on deal is just a short term experiment to directly compare drivers. I seldom run my system over a few watts anyhow. Al K.

Evil, I have not see the inside of an Altec or JBL driver, but I am about to listen to a set! This little gizmo adapts a standard 2 or 3 hole driver mounting to the 1-3/8 X 18 thread used on the K55 diver. It is going to let me screw in a set of used JBL 2421 full range drivers on my Belle Klipsch to see what they sound like. They only cost $6.01 each from MCM Electronics (http://www.mcmelectronics.com). They are catalog number 54-500. Al K This message has been edited by Al Klappenberger on 05-26-2001 at 08:00 AM

JonM The K55V and M drivers have their resonance well BELOW the operating frequency range. The 9 KHz "return" is not a resonance. Rather, it just looks like an extension of the frequency response. You might just call it a very rough roll off. The classic series connected "P trap" operates by effectively opening the circuit to the driver at 9 Khz. This does no harm. Connecting the L-C as a shunt trap is trying to short out the source at 9 KHz. This is why the resistor is needed. The single series cap in the squawker does not provide a suitable series impedance (reactance) to allow this. It's too large. The "elliptic" tweeter filter has the notch at 5000 Hz which is below the 6000 Hz cutoff of the filter. This sharpens the lower skirt shape protecting the tweeter by removing high power low frequencies. It makes the filter skirt MUCH sharper. The trap is located on the output side of the filter allowing the rest of the filter to operate as the series impedance the trap is operating from. It does not load down the source since the trap is actually part of a complete filter designed for 6000 Hz. The single cap in the squawker, on the other hand, is a filter designed for about 400 Hz which is well below the 9 Khz trap frequency. That's why the value is so large compared to those in the tweeter filter. Al K

John, A single inductor would simply be a first order lowpass and would not yield enough attenuation at 9 KHz. The network I offer uses a second order lowpass and yields about 8 dB. That is just about the minimum to do the job. A trap (in sereis) will do a far better job. Al K.

JonM The analysis shows that an 8 ohms in series with the trap is high enough that the trap does virtually nothing. 1 Ohm yields about a 10 dB rejection at 9000 Hz. Using no resistor at all in series with the trap reduces the impedance to that of the component losses. This will be nearly that of the "Q" (X/R) of the .1 mHy inductor used at 9KHz. With a Q factor of 20 (assumed) the R value will be about 0.28 Ohms. This is too low. An 8 Ohm resistor connected directly across the squawker driver (outside the trap) does nothing except lower the impedance a little. I mention this because I am not sure how you proposed to connect the 8 Ohm resistor. Connecting the L and C as a parallel trap connected in series avoids the resistor question entirely. Al K.

JonM I did some computer analysis on the AA network model and discovered that the "P trap" of 3 uFd and .1 mHy worked equally well parallel connected in series as it does series connected in parallel. The 8 ohm resistor does not accomplish anything useful though. Connected across the driver, it simply reduces the squawker level. Al K.

Tom, Yes I know of "Esper". That is "Audio Referbishers". I think the guys name is Tom Manley. Anyhow, I got my MCD7007 CD player from him. It turned out it had a tracking problem when I got it. It had just been worked on my McIntohs and they couldn't find the trouble becasue it wouldn't malfunction when they had it. I found ot myself that it was heat related. Mr Manley took it back and had it sent to McIntosh again and repaired right. The drive motor was bad. It was returned at no extra charge and the 1 year warranty rest to the day I got it back. It has been perfect ever since. I think his prices are a bit higher than Audio Classics though. Al K/

Tom, Here's some good info on the Mac C27 (all all the rest of thier stuff too): http://www.sundial.net/~rogerr/preamps.htm#c27 Al K.

Tom, I second what Fred says about Audio Classics. I have bought most of my Mac stuff from them. They are very reliable. I even got the meters and knobs for my home-made power-monitor / scope from them. Interesting foot-note. Klipsch is using a Mac C28 to run the amp for their anechoic test chamber in Hope. I really don't know what that implies though! AL K.

Tom, As an avid "old" McIntosh fan, I suggest virtually any model! I use the C34V myself and I love the "Compander" feature. It will reduce the noise associated with FM stations very nicely when set to expand. I have also used a C27 and it was very good also. The one most people seem to think is the one to avoid though is the C28, but I am really not sure why. Al K.