g3dahl

Oh, yeah, I forgot about that unusual configuration. I went back for a look and see what you mean. Only two 2-uF caps for a 3-way crossover! Clever design, and a pretty lucky situation if you're replacing caps. Personally, since you can do all three channels with six caps, I would just go for the Hovlands and be done with it. $14 for the 2 uF Hovlands is an excellent deal. I use the same caps in the tweeter section of my modified Chorus II's, and am very happy with them. If you want to proceed more cautiously, consider buying three Hovlands, then use one Hovland and one Zen in each speaker. Put the Hovland between the input and the autoformer, and the Zen between the autoformer and the tweeter--that way, you're using the best cap in the position that influences the signal going to all three drivers. Or, for maximum bang-for-the-buck, just put a couple of Zens in your new center-channel speaker. You can't go wrong, because you know you like the sound already. But above all, make sure all three crossovers are done the same way. Have fun! Gary Dahl

You might check the forum at: http://www.hometheaterspot.com Gary Dahl

If you like the sonic "flavor" of the Zen caps in your system, then I suggest that you use the same ones in your center channel. The difference between the sound of the Zens and the Hovlands is most likely smaller than the difference between either and what you replaced. Also, it is highly desirable to match the front and center channel speakers as closely as possible, so you don't want to introduce a different flavor in the center. The Hovlands are more expensive because they are built with film and foil construction rather than metallized film. North Creek (the distributor of Zen capacitors) also offers film and foil caps under the name "Crescendo". They are priced more comparably to the Hovlands. Film and foil caps are certainly excellent, but not always better than a good metallized cap. I have used (and continue to use) Hovlands, Auricaps, Zen and Crescendo capacitors in various locations. If you want to experiment with Hovlands, a good starting point would be to just replace the tweeter capacitors; that is where the difference will be easiest to hear. If you really like the way they sound, then you can move on to the mid if desired. For the woofer section, an inexpensive metallized film cap will work just great. Gary Dahl

---------------- On 9/9/2003 6:40:50 PM wrench_peddler wrote: Question 1. Is it bi-wiring when you run 2 leads to the speakers, One for the lows and one for the highs, both from the same source? Yes. Question 2. Is it bi-amping when you use two amps, one for the lows and one for the highs? Yes. Question 3. Is a bi-amped speaker also bi-wired by default? Yes, but the term "bi-wired" is normally only used as you described in Question 1. As for bi-amping, there are two ways to go about it: Passive bi-amping: Using two amps, one for the lows, and one for the highs. The crossovers (passive) are in the speakers. Active bi-amping: Using two amps, one for the low, and one for the highs. The crossovers (active) are ahead of the amps, so the amps' outputs go directly to the drivers. Gary Dahl

Hi kh, The name "Aloha Audio" made sense at the time, because it was a partnership between Hiroshi Ito (who lived in Honolulu) and Lynn Olson (who lived in Aloha, Oregon). Lynn started the name "Nutshell High Fidelity", back before his Aloha Audio days, for the purpose of distributing his book, "The Soul of Sound". Aloha Audio began when he and Hiroshi decided to start importing Danish Audio Connect (DACT) attenuators. The "Nutshell" name was the result of a conversation between Lynn and his brilliant wife, Karna. He had been talking about the concept of designing the speakers and amplification chain as an integrated whole. She said something about that being his whole philosophy in a nutshell, and ended up suggesting that as a name for his business. Lynn and Hiroshi dissolved Aloha Audio near the end of last year. The replacement has been Nutshell High Fidelity, with a return of the old name. It consists of Lynn and me. We import DACT, and plan to eventually sell amps and line stages of our own design. It really doesn't rain all that much around here, less than in Seattle. It's more of a myth, actually, though there usually is a long stretch of gray skies through the colder part of the year. Gary Dahl Nutshell High Fidelity http://www.nutshellhifi.com

Interesting thread! As it turns out, Allen Wright, the other VSE guy, is coming out from Germany in about three weeks to attend VSAC here in Silverdale, Washington, where he will be a guest speaker. His seminar will be on the topic of push-pull amplifier design. He also will be bringing his new amps that he is bringing to the show for their debut (not the Rasmussen design you have been discussing). He will also be bringing his amps to my house to compare with my Lynn Olson-designed Aurora/Amity amps (see http://www.nutshellhifi.com/triode1.html). Lynn Olson is my partner in Nutshell High Fidelity (formerly Aloha Audio), lives here in Silverdale, and has recently begun to participate in the Klipsch forum. If you have questions about how to reconcile his writings with other pieces of information you run into, just ask...I'm sure he would be happy to explain further. If you have questions about the Rasmussen stuff, maybe I can pry some info out of Allen. I'm sure he's well versed in it. Gary Dahl

---------------- On 9/6/2003 1:58:07 PM fini wrote: Thank you, Gary!! Have you gone in the past? Sounds like a good place to get an education. I plan on tasting Sonoma County's finest at the Harvest Fair, happening that same weekend. Anyone need corks for their Cornwalls? I can already taste that Dry Creek Zin... fini Hi fini, Sounds like a good time! As a matter of fact, I've been to all three of the VSACs. What I didn't know when I went to the first one was that by the time the second came around I would have moved to Silverdale! It wasn't the reason I moved here, but it is handy living less than two miles from the venue. The strange thing is that any time I happen to walk into the Silverdale Red Lion Hotel, a part of me expects VSAC to be going on... Hope you can make it next time, it has been growing steadily and this year's VSAC has actually outgrown the hotel! I'm not sure if the next one will be in Silverdale, though. Gary Dahl

Biwiring most certainly does make things better. Have a look at: http://www.geocities.com/jonrisch/page8.htm The graph that the above URL leads to shows a rather dramatic difference. I recommend backing up to the home page and exploring the many fascinating articles on Jon Risch's site. The index page is at this address: http://www.geocities.com/jonrisch/index.htm Have fun! Gary Dahl

---------------- On 9/6/2003 12:22:51 AM fini wrote: What/who/where the Hell is VSAC? fini ---------------- VSAC is "Vacuum State of the Art Conference", October 3-5, Silverdale, Washington. Details can be found at http://www.vsac2003.com. This will be the fourth VSAC; they have been held at 2-year intervals. Seminars will be led by Allen Wright of Vacuum State Electronics, Bruce Edgar of Edgarhorn, and Charles King. Exhibitors include all kinds of tube-related companies and high-efficiency speaker makers, such as: Bottlehead Welborne Labs Modwright Firefly Audio Progressive Engineeering MagneQuest Exemplar Audio Lowther America First Impression Music Wright Sound DIYcable Consonance Adire Audio Iconic Manufacturing Cain&Cain electronluv Jena Labs Bent Audio Hagermann Technology LLC Teres Audio The Bolder Cable Company Galibier Design K & K Audio Aliante loudspeakers Amazon turntables Audion tube electronics Audist loudspeakers Cadence Audio Edison tube kits Nightingale tube electronics Revolver loudspeakers Royal Device loudspeakers Experience Music Edgarhorn Rethm Loudspeakers Omega Speaker Systems Experience Audio Tubeseller.com Solar Hifi GR Research Sun Audio & Two Bald Guys Audio Cardas Audio Hudson Audio Audio Amateur Corp. Oris Horn Diversity Records Harmonic Design Works Redpoint Audio Design Gary Dahl

---------------- On 9/4/2003 4:08:49 PM PAR69 wrote: Another option might be to change the phase of the Cornwall woofer by swapping the leads off of the crossover (positive to negative/negative to positve). Any one see a problem with this? Paul ---------------- Yes, there would be a problem. Reversing the leads between the crossover and the woofer would cause a response null at the crossover frequency. The relative polarity of the drivers is part of the crossover design, so you can't change it without redesigning the crossover. Kerry, if it were my system I would reverse the polarity of the Cornwall, as you did. The idea is to connect things so that the listener receives the same part of the waveform from all three woofers. Because of the longer path length in the LS's, this is achieved with the Cornwall (or both LS's) connected in reverse polarity. Gil is probably right, though, about it not being terribly critical in this application, as PWK wrote. You should feel comfortable making your final decision by ear. The answer might not be particularly clear, because the phase relationships between the mids and tweeters will be all over the place anyway. I would base my decision on the woofers, which are covering the frequency range in which the ear is most sensitive to phase relationships. Gary Dahl

I have now had the opportunity to listen to the Chorus II's with the completed modifications. The results are fabulous! Wow!! The flatness of the frequency response is immediately obvious when listening to music. There is a beautiful transparency, a very strong "you are there" sense. I have never heard a horn system that was completely free from audible peaks and resonances, especially when listening to orchestral music. Strings are *really* hard to get right with horn systems (or even with direct radiators, for that matter), because any such peaks or resonances, or bits of distortion, destroy the delicate balances that allow strings to sound like they do in real life. Last night when listening to the Telarc SACD of Berlioz' Symphonie Fantastique, I was treated to the most sublime orchestral reproduction I can recall. During dense passages, the tone colors of individual instruments were clearly delineated--the lack of any sort of glare was revelatory. The resulting sound was also quite refined. The delicate violin passages in the opening of the first movement brought goosebumps! I'm not ready to say that the Fostex tweeter offers the last word; there are some very nice units out there that I'd love to try at some point. But if it doesn't get better than this, I am already very pleased. There is also a minor hump in the midbass response that I would like to get evened out. Experimenting with placement might help, but I am also curious about how the original Chorus (vented bass reflex) alignment sounds compared with the Chorus II's passive radiator. I wouldn't hesitate to ditch the PR and cut some ports if it will improve bass smoothness. With that being said, the bass sounds quite good even with the hump. The hump is broad enough that melodic lines played in the lower ranges don't seem to move in and out of an exaggerated response area. In fact, to my ears, the bit of extra warmth makes cellos and basses sound more realistic than they often do in systems that measure "flat". This has always bugged me; in real life, lower strings make a big, warm sound, not something you would call "lean" or "tight". So...what's really right? Looking forward to more listening. Congratulations Lynn, you've really outdone yourself this time! I think you should come over tomorrow for a listen. You'll really like what you hear. Gary Dahl

I have put some time into working with DIY CAT5 cables. My suggestion: keep it simple and compact. For example, use a single CAT5 (teflon, like Belden 1585A or equivalent) for a speaker wire from one amp channel to its speaker. There are four twisted pairs inside, each pair made of one solid-color strand and one striped strand. You can either connect all of the solids to red and all of the stripes to black for minimum inductance (split pairs), or use two twisted pairs going to red and the other two going to black. Most people using CAT5 have used large numbers of strands in various braiding configurations. It is quite easy to build up to a very large capacitance while doing so, especially with split pairs. This capacitance is parasitic, and results in HF losses. With high-sensitivity speakers such as Klipsch, it doesn't take a big heavy speaker cable to do the job. If you don't believe me, open up a CAT5 and replace your speaker wires with just one twisted pair (2 x 24g!) and have a listen. See what I mean? Of course, repeating the experiment with low-sensitivity speakers will bring about different results. If you go to the effort of building a big cable out of many runs of CAT5, you might even be very pleased with the results; many folks swear by the stuff. But you might have fun trying some smaller configurations first. They're cheaper, easier to build, and will give you a feel for how the stuff behaves in your system. Good luck! Gary Dahl

One thing I didn't mention when describing the crossover circuit: the 20 ohm series resistor has been removed from the squawker. Gary Dahl

For the purpose of measurements, we placed the tweeter on top of a couple of thick books (Harry Potter #5 and The Adventures of Sherlock Holmes) and used a folded-up bath towel to cover the rest of the enclosure's top surface. Obviously this worked, because the impulse response measurement results came out very clean. Eventually, I will build a wooden enclosure for the tweeter, and try to come up with a sound-absorbent treatment for the cabinet top that is reasonably attractive. There were quite a few changes to the crossover. Going from memory: The second tweeter cap (2 uF) has an extra 4.7 uF in parallel, and there is now a 50 ohm resistor in parallel with the Fostex FT17H tweeter. The polarity is reversed, as in the original. On the squawker, the Universal 3619 autotransformer has a 10 ohm resistor in parallel (a la ALK). Output is taken from tap #1. Squawker polarity is now reversed. For the woofer section, the capacitor has been changed from 68 uF to 20 uF with a 3-ohm resistor in series. BTW, the 3-ohm value turned out to be critical. The inductors are stock, as is the first tweeter cap (also 2 uF) and the squawker cap (6 uF), though all caps have been replaced with premium-quality polypropylene films. This crossover is for the time-aligned version with the Fostex FT17H tweeter on top of the cabinet only! With the stock tweeter in its normal location, best results were obtained with different parts values...but the response was not nearly as smooth as our final version using the Fostex tweeter. Also, the Fostex/time-aligned version has much cleaner impulse response. I will post again when I have had an opportunity to listen to music! Gary Dahl

Lynn and I got together for another round of Chorus mods. This time, the goal was to see how far we could go with the stock woofer and squawker, but using the Universal 3619 autoformer. I brought the original Klipsch tweeters as well as the Fostex FT17H's. We started with the Klipsch tweeter, and the autoformer set on tap 2, which is one step lower than it would have been with the original autoformer. The tweeter crossover used stock values; the woofer and squawker were set the way they had been at the end of the Altec experiments. We had lots of trouble with the Klipsch tweeters because the joint between the terminals and the voice coil wire is easily broken. I was able to re-melt and get them working again a few times but eventually they couldn't be revived. Better to mount these tweeters and leave them be, rather than subject them to what I did! Anyway, we had already optimized the crossover while we still had a working Klipsch tweeter, and I have more diaphragms on the way. So, we turned our attention to the Fostex tweeter. By this time, we were experimenting with a time-aligned configuration, with the tweeter on top of the speaker enclosure, set about a foot back from the front panel. Once everything was dialed in, we had a remarkably smooth and flat response, far superior to our previous efforts. Now I will have to build the changes into the "permanent" (Ha!) crossovers so we can start listening to something more interesting than MLSSA test signals! Lynn will be posting the MLSSA plots when they are ready, and perhaps the schematic. The topology is mostly similar to the original, but most of the cap values have changed, and resistors are used differently. Gary Dahl