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Hi John, There is an active Dahlquist group over at Yahoo that has a world of info. I am attaching an essayThe DQ10 Reconsidered 2010.pdfThe DQ10 Reconsidered 2010.pdf I wrote about my DQ-10s, which were destroyed in October by hurricane Michael. I'm not going back to DQ-10s, although I miss them very much. (I saved the mid bass drivers) . Instead I am going with Heil Air Motion Transformers (AMTs) and some 12 inch woofers I have on hand. My study needs to be rebuilt so it will be some months before all that comes to pass. You can PM if you like to discuss Dahlquist stuff. My main set uses Cornwall IIs, which were unharmed.

My quick & dirty test set up. Roughly 900 Hz (50 uF). Yeah, break in is key. The non-polars in my cap substitution array had never been used and the sound changed as they formed up. Still impressive in the narrow vertical window. A wild thought: if used with corner bass bin, absorb the back wave and turn the AMT vertical to have a tall spray of HF, less sidewalk anomalies,. at the expense of the middle, in which we'd have a distinct hole, without a center channel.

This looks like a Shorthorn from the 50s with two 12s.

That's my plan (sort of) I have some good 12 inch Visaton woofers, and I plan on a cab 14 by 16 by 28, with the woofer at top of the motorboard and the vent at the bottom (maybe down-firing with short legs on the cab). Those dimensions don't include the height of the AMTs. My second iteration will be to raise the AMTs up on platform and put some Phillips midranges (rescued from wrecked DQ-10s) underneath with a felt pad on the back ala the DQ-10 pseudo-TL.Crossover at 250 and 1 KHz. I'm thinking of using series network for the woof and mid and then a parallel branch to the AMT, so the impedance will still be in a reasonable region.

Here is Hiro (my avatar cat), 12 years ago, checking out the Crites tweeter in my Klipsch-derived center channel. Wish I could port his hearing to a scope...

A young hawk sitting on my guest's car. My neighbors across the street have two chickens (down from four) who cross the road to peck around in my yard. This fellow must have figured it out.

My AMTs are en route and I am starting to sketch out cabs for them. It will be interesting to see how these differ from either my Corns or the now lost DQ-10s. Thanks again for the measurements

I see you have an auditor with very keen hearing helping you. Mine assist me as well, although they tend to fall asleep at random times.

I guess those plates do form a waveguide, to an extent, but there is no top. The bottom would be formed by whatever the top of the bass bin is. Thanks for all the measurements you've posted. They are very helpful since ESS offers no data to speak of.

This is the first time, in my 14 years on the Forum, that I read die-hard Klipsch guys adoring a non-horn technology. I recall the original AMTs in the 70s. I need replacements for my hurricane-destroyed Dahlquist DQ-10s, which were my study speakers. (The Corns are fine). I have 2 Great Heils on order and I am thinking of using them with the DQ-10 Phillips midranges with some 12 inch woofers I have on hand, crossing at 250 and 1 KHz. These will have a foot print of no more than 14 by 14, reaching a height of about 34-36 inches. The mid will be in a felt-covered open back (as Dahlquist used them) which creates a sort of transmission line. The study won't be back together for a few months, alas so I have plenty time to plan.

This looks like a Western Electric horn from the 1930s

For background, I drove Grand Marques for 22 years. Ford lost interest in those cars long before they were discontinued (the Panther chassis) and the technology and quality fell behind. A mechanic buddy reecommended Gennies and I drove a a two-year old '12 and fell in love. Like going from the Queen Mary to a destroyer. I like everything but the fact that sometimes the AV system doesn't come on. The Hyundai Genesis forums are mainly the realm of those who want to hot rod the cars, not fix intrinsic problems, so they have been of little help. I did, however, score a free service manual from the forum owner. The Lexicon stereo is amazing, which makes the stuck CD issue all the more annoying. I have to say that not only is the Lexicon the best car audio I've ever heard, but it is also one of the best audio systems I've ever experienced. Being tuned to the cabin, it is milers beyond anything aftermarket I could afford, and since I mainly listen to classical, I don't need boom-car bass.

I have a CD stuck in the changer of my 2012 Genesis. Various remedies were suggested on the web: 1. Remove both fuses for 10 minutes to make the AV system perform hard reset. No Joy. 2. Attempt to load another desk while holding on to it, in the theory that it will "grab" the stuck disc enough for the changer to spit out the stuck one. Nope, nothing happened. There are other remedies involving crotchet hooks and double--faced tape, but I am not about try those for fear of damaging the changer (a costly item). I know how to get to the changer from a YouTube vid, but that's last resort. The Genesis forum yielded one non-helpful response. I'm not even sure why the CD is stuck; it doesn't have a label (quit using CD labels long ago). Any non-invasive ideas?

I might add the we are all back home now. My ISP has still not restrung fibre out our way so for the moment I'm using the phone as hotspot to get to the web. Just like the olden days when I had a 56K modem and was lucky to get 33.6.

Panama City

Thanks. We have trailer out back for bed & bath. The kitchen and laundry are intact and can used;; the undamaged part of the house is reenergized. We have had a lot of help for which we are truly grateful.

Well, my partner, I and our cats survived. The house took serious damage and we are in a condo friend has lent us. The Forum will probably be interested to know that our Corns and Klipsch-derived center all survived fine. My Dahlquist DQ-10s in my study, which was hardest hit of all the house, did not. I did save the Philips midranges which are unobtanium now and someday I will build a pair similar to the DQ-10s with more modern technology. I do not have regular internet access yet so any replies may be delayed by a day or so. Scott

Going back to the OT...I believe Paul was an only child. Jim Hunter would know.

The CW cabs are the easiest to make of all the Heritage line (with the exception of the Heresies, of course). Rather than modify and possibly damage existing cabs, I suggest you just make new ones. The plans have been posted on the forum many times. I have a pair of 1986 CW IIs that have cab damage from poor packaging in shipment. One day, I will have (or I will make) new cabs, and put the woofer to the new height on the motorboard.

What Don said! The phase plug is not decorative. Without it, phase cancellation will produce a deep dip in response at some frequency. The K77/T35 series of tweeters used a two-piece "Avedon" phase plug which was a marvel for the late 50s but has been superseded by better designs now. EV Avedon T35.pdf

Didn't realize Palladium had been discontinued. When did that happen? Some plastics deteriorate faster in homes with gas heat. This was especially true in the olden days with the now-illegal unvented gas heaters we grew up with in the South.

The faux corners came out in a Dope from Hope in the 1970s. Gary Gilium designed them. I believe PWK used them in his own home due to lack of suitable corners.

Not aware of ports within the horn, which would destroy the "horn action". Decades ago, Paul joined the back volume (Vb) of the enclosure to the "sinuses" on either side of the first expansion, which reduce dthe driver plus Vb resonance (not the horn resonance) somewhat. Going by Heyser's review, I *think* that resonance is about 55 Hz, and the horn resonance, i.e. the effective cutoff, is about 37 Hz. Of course, there's output below that. IRT the K400/401: I think, beyond Paul's control of the design, the corporate decision was not to alter the proportions of the Klipschorn by installing a bigger midrange horn. The K-5 series occupied almost all of the frontal area of the top hat, and the various tweeters were lodged in the mouth. That was never optimal, since there was marked interference at crossover. A bigger midrange horn would drive a taller top hat to allow the tweeter to be above the mid, as it has been since the K-400 was introduced.

Of course, but let's remember that PWK changed the midrange horn and the driver at least twice, and also changed the tweeter at least twice as well. There were I'm sure, incremental changes that I'd have to dig to identify, but the point is, PWK continued upgrading the Klipschorns until sometime about 1980 or so. I think the changes that were made after that had to do with driver availability. The bass horn is, if I may presume, what I think Roy was talking about. The factory-enclosed back is a change that was field-tested by many people over the years and it's only logical. I speculate that there have been some minor changes to the bass horn assembly in the interest of rigidity.

A Celestion tweeter driver? CDX07-1075 maybe?