Fjd

I believe that harmonic distortion is reduced because the variations in each of the driver’s cones, spiders, and suspension are cancelled out because one driver will be inversely proportional to the other.

I haven't seen an owner's manual. I wonder if Mark ever had a manual supplement for the cream version?

low output moving coil

We had a “progressive” high school with a student lounge that had a Pong game (Atari) and an air hockey game. Also, seniors had a smoking lounge, but needed a note from a parent. I also remember smoking on airline flights and every car had an ash tray or two. I also had a couple of the earlier home computers - Commodore VIC-20 and a Commodore 64.

There may be “technically” some “output” at 20Hz, but I don’t see how you can get anything audible at 20Hz on a ported box tuned to about 38Hz. I imagine you might get some level of smoothing of the response curve, but I don’t believe there would be an audible difference. If you stuff a sealed box with fiberglass (not just lining the walls), the stuffing tends to “fool” the woofer into thinking it's in a bigger box and could give some bass extension (but probably not 40Hz to 20Hz).

I don't specifically know the measurements, but here is a link to another thread that discusses size/angles. http://community.klipsch.com/forums/p/34761/305255.aspx#305255

For home use they would probably have a low WAF; however, the 1233 is a musical sound portable loudspeaker system with the following specs: FR: 50-20kHz, vented Power: 120 watts, 8 ohms Sensitivity: 100.5 dB SPL Dimensions: 33"H X 28"W X 19"D, 112 lbs Components: 421-8LF, 811B horn, 808-8B driver 1233 xover (1200 Hz dual LC network). http://www.altecpro.com/pdfs/vintage/SpeakerAndMics/systems/1233%20Speaker%20System.pdf You could also try the Lansing Heritage site or the Altec forum on Hostboard for more specific information/opinions.

Check this link. http://community.klipsch.com/forums/t/73719.aspx?PageIndex=1

DL 15x is a Electro-voice 15" low frequency driver http://archives.telex.com/archives/EV/Drivers/EDS/DL15X%20EDS.pdf Klipsch K-33 15" low frequency driver SPEC 15162 PART # K-33 RE OHMS 3.39 FS HZ 34.46 LE MH .96 MMS GMS 78.59 QM 7.39 CMS mm/N .2714 QE .410 RMS NS/M 2.3037 QT .390 VAS LTRS 301.66 XMAX MM 8.20 SD SCM 889.59 BL TM 11.88 EBP 84.4 EFF % 2.91 SPL dB 96.6 Wattage 150rms With a DIY project I believe that a person needs to compare all T/S parameters and understand the impact the parameter differences between drivers that you are evaluating will have on the finished product. Here is one comparison: DL 15x Fs = 42.00 Hz; K-33 = 34.46 Hz Per the graph in the link the DL 15x shows the bass response rolling off pretty fast below about 50Hz. I don't have the crites woofer specs, but I believe that the CW1526 Fs ~ 27 Hz. I believe that the Crites woofers are a very close approximation to the old K-33 15" Klipsch low frequency drivers that were sourced and used by Klipsch before 1984 or 1985 (I'm not certain on the year Klipsch changes to the specs above, which have the higher Fs).

DeanG: “What might make a real difference is removing the core -- an air core autoformer would be cool, but most probably wouldn't make the investment if they were available.” Dean has a fascinating idea with an air core transformer (since a transformer is just a couple of inductors that share a common magnetic path) even though the market probably doesn’t exist to make it profitable. Just like an inductor, the transformer core is subject to the phenomenon called hysteresis and, although the hysteresis loss is typically small, an air core transformer could eliminate this. Without more description from the builder, the build quality is difficult to assess in comparison to the model made by Universal Transformer. For example, a larger gauge of copper wire may help heat dissipation due to winding resistance, but from pictures it is difficult to determine just how much more copper may be packed into that space as opposed to the Universal model. Also, if the builder uses bifilar winding technique as the Universal uses per Dean, which bifilar winding will produce much more energy over a single wound coil. What core material is used and are there any advantages/disadvantages to this core material if different than Universal Transformer? What does Universal Transformer do in comparison to this builder as the individual wire turns must be electrically insulated from each other to ensure that the current travels throughout every turn? Situations with low current and differences between adjacent turns is small, enameled or varnished wire seems fine; however, some companies will attempt to replace air spaces in the windings by saturating the windings with epoxy or some other substance. I noticed that the builder does offer custom incremental changes in dB for the taps and the 1.5dB differences over 14 taps can offer a wide range of DIY potential. Just like the ferrites vs. neo vs. alnico vs. field-coil arrangements for speaker/transducer motor assemblies, there is a debate on “best” for tube amps on c-core design vs. EI-core design output transformers. I have an acquaintance that swears by c-core design over the traditional EI-core design for tube output transformers, but I don’t believe that should be the sole measure of a purchase decision. With other factors being equal, I suppose there may be merits & limitations of both designs when a transformer is inserted in a signal path as an attenuator.

One additional aspect that may not be covered by the link above is the sensitivity of the K33 driver. Hopefully, a person with more specific knowledge can verify, but I believe that the Crites woofer is 97 db 1 watt / 1 meter. I suspect the K33 was similar, but I'm not positive. Also, you may find the information interesting and useful regarding various 15" drivers that were modeled for the Khorn using the "Hornresp" modeling program. However, it does take some work to decipher the results. http://forums.klipsch.com/forums/t/117141.aspx?PageIndex=1

Check this link to an old forum page. I haven't checked the accuracy of the parameters presented, but the page should provide you with some useful information if you are checking with local speaker vendors in an effort to reduce shipping costs for a possible driver that would perform similar to the K33. http://community.klipsch.com/forums/t/86.aspx?PageIndex=1

Great work & Happy Birthday Al![^] Q: What is the difference between hearing a K-400 and being tortured? A: One is far more painful to your ears.[] Q: How many people does it take to modify a Klipschorn? A: Fifty. One to do it and the others to stand around and say, "I could do that better.”[8-|]

I believe that most of us on the modifications pages are infatuated with the potential of what arguably better drivers and modifications could do for our iconic Klipsch Heritage loudspeakers given Paul’s penchant for “making the proverbial silk purse out of the sow’s ear.” However, there were not many companies “overbuilding” the way JBL did with some of their iconic drivers (i.e. LE15A, 375 & 077) so I believe that Paul was not necessarily alone. I believe it was back around 2002 - 2003 that the Beyma CP25 was identified on this site as a viable low cost alternative to the K77, although modifications would be required as the horn was different and needed a different baffle cut-out. The JBL 2404 was always a contender for a modification alternative and this link was one of the first I found that mentioned the JBL 2404 and the Beyma CP25 http://community.klipsch.com/forums/t/15166.aspx?PageIndex=1, then I found the The Audio Engineering League link for the specific Klipschorn modification and John Warren’s JBL 2404 modification here http://community.klipsch.com/forums/t/40135.aspx?PageIndex=1. However, the JBL 2404 was selling upwards to $287 each while the Beyma CP25 could be obtained for $60 each (although it wasn’t apparent that the sales were through a rogue seller at the time). Now the JBL 2404 is NLA new, but the Beyma became one of those cases where you get the old 80/20 rule (arguably “80% of the benefit for 20% of the cost”). In terms of distortion, if you compare the JBL 2404 to the Beyma CP25 the distortion is clearly a lot lower on the JBL; though that’s not to say the Beyma tweeters are bad. This is not new information. Fast forward to today and we have a lot of “new products” from different manufacturers that may be very viable as the next great 80% performance for 20% of the cost deal[]. I don’t know about others, but I enjoy making different and hopefully nicer sounding loudspeakers and the testing specifications that are posted helps me validate what academically looks good in what I’m trying to accomplish. In some respects, these debates brought to mind something Mohammed Ali once said that “The man who views the world at 50 the same as he did at 20 has wasted 30 years of his life.”[] I agree with DeanG in “…..certain people will end up trying them all, and some will simply prefer the sound of one over the other. Whichever they choose, I can bet they won't be coming back in here saying they picked the one they did because of Al's plots;” however, the plots help identify viable alternatives for our intended applications. I also agree with Dkalsi that there is room for healthy competition[Y] and hopefully the consumer can see some benefit too. The good thing is that we don't see signs of collusion on this thread......[]

It seems like Al has presented good information that a person involved in modifications could consider when developing design goals. If we can keep it in the proper context, the information can help many. This thread does remind me of the old carbon comp vs carbon film vs metal film resistor debate where many people believe that wire-wound resistors are the best choice for low noise, followed by metal film, metal oxide, carbon film, and lastly, carbon composition. The most interesting (and maybe relevant[8]) thing is that many people prefer the "sound" of carbon comps and claim the carbon comp resistors sound “warmer” than film or wire-wound resistors. I’ve read that the most likely reason is that the sound could be attributed to "distortions" generated by the modulation of the contact noise current by the AC signal. Given that this noise has characteristics that are similar to pink noise; many people may find it more pleasing to the ear than white noise. However, when considering your design goals, “pleasing noise” is still noise, and in many opinions, one of the design goals may be to reduce "noise" to the lowest possible level.[^o)] Also, to keep the measurements in the proper context, the equipment that Al lists on the first page would not be considered a “battery checker.” The HP 3562A/3563A series of analyzer was originally listed at a MSRP of $22,000 - $26,500 (although I believe that it is 1990’s or 80's technology[:-*]). Here is an overview of specs http://www.home.agilent.com/agilent/faqDetail.jspx?cc=FR&lc=fre&ckey=489086&nid=-536902471.536882157&id=489086. In addition “consumers union” has made a living “testing” and “validating” manufacturer’s assertions.[]

- The Kentucky Headhunters http://www.kentuckyheadhunters.com/ - Insane Clown Posse http://www.insaneclownposse.com/ - Violent Femmes http://www.vfemmes.com/

There are many calculators on the internet to calculate parallel resistance; however, if interested, here is an illustration of the formulas as I understand them to manually calculate the resistor value for each autoformer tap to maintain a certain impedance, since technically the swamping resistor value would be slightly different for different attenuation levels related to that chosen tap. You could calculate a more precise autoformer impedance (turn) ratio of the specific autoformer tap being used (to further reduce any slight drift in crossover point from the mod); however, the schematics on my link above show the impedance ratios for the T2A autoformer (just not at a very precise decimal level). Also, please keep in mind that the factory capacitor value was selected with the factory tap selection; therefore, a person cannot arbitrarily follow my example, but must understand their specific application before applying this theory. The example is designed to show how the parts in the network/circuit interact and I believe the principle can be applied to any autoformer. I should probably add a disclaimer that this was my first attempt at a simple modification (to attenuate mid-range without wholesale capacitor changes) that was low cost and reversible, but I do not believe that it is a substitution for a properly enginered longer term solution. Attenuate 12 dB Mid-driver impedance 11 ohms autoformer impedance (Turn ratio) 16 x New impedance 176 = Desired impedance 8 ohms Parallel Resistance formula =1/((1/8)-(1/(11*16))) 8.38 resistor ohm value Attenuate 6 dB Mid-driver impedance 11 ohms autoformer impedance (Turn ratio) 4 x New impedance 44 = Desired impedance 8 ohms Parallel Resistance formula =1/((1/8)-(1/(11*4))) 9.78 resistor ohm value Since total parallel resistance is calculated as 1/Rtotal = 1/R1 + 1/R2 + 1/R3 +...... , in my example I just try to solve the equation for the unknown (mom always told me math really could be used in the real world[]...or maybe I should have paid more attention in class...[^o)]).

Hello Dave, Congratulations on your work, it looks like it is well respected and well received. I addition, I did not discuss that you also have to move the mid-range driver to a different tap on the autoformer, and I acknowledge that not changing the capacitor is not the best approach, but it does work (I believe that all this is well documented in old threads, which is where I initially found the concept related to Heresy here http://community.klipsch.com/forums/t/21971.aspx then studied how it worked). I was just stating that the swamping resistor to change the attenuation was my first ever modification (monumental for me at the time). I believe that audio and DIY modifications are a journey and a person really needs to understand themselves to start that journey and better understand what they like (and why) and which modification would be best for their specific situation or give the best return for budget. I agree that tractrix horns are great for the home listening environment and I actually have four pairs of tractrix horns (two pair that accommodate 2” drivers and two pair that accommodate 1” drivers). In addition, I’ve used many different driver combinations in DIY projects and now currently run the AlK extreme slope crossover, TAD TD-4001 mid drivers, Lambda TD15M woofers and Fostex tweeters in my Khorns. I also have a pair of JBL 2450 drivers that I’m contemplating installing a pair of the Brush Wellman Beryllium Truextent diaphragms. However, while I think that my combination is great to me and almost gives me an “electrostatic feel” to the music detail and resolution while maintaining the great dynamics of compression drivers and horns, I would never blindly recommend the combination to anyone without knowing somebody’s music history. Hence, my list of questions. Also, I don’t have any delusions that I actually have design goals, or think that I’ve made any real improvement to my Klipschorn. I do know that I like my various hobbies (audio being one of them) and I believe that I’ve just made a different and hopefully nicer sounding loudspeaker based on arguably better drivers using the iconic Klipschorn box.

It looks like SET12 and Cask05 have both offered great observations. However, for a general view, if you search the forum, you can find a large amount of information and listening opinions regarding various upgrades/modifications. For a more specific opinion, it may help the forum readers in offering more specific tailored suggestions if you could articulate more specifically what you don’t like about the Klipschorns and what have you done to improve your listening environment. Also, it may help readers to understand specifically what you like about the Klipschorns. For example; What attracted you to Klipschorns in the first place since many horn designs can be perceived as having “piercing” upper frequencies? On a side note, there is a great thread on the forum titled “How were you "introduced" to the KLIPSCH Heritage Line?” What type of loudspeakers have you listened to in the past? What volume levels do you listen at? What type of audio equipment and source material are you using? What is your price range for modifications (my two swamping resistors cost $3.75 each and a little solder, while some modifications can run several thousand dollars)? Do you listen primarily to music or home theatre? What type of music do you listen to? What is the size of your listening room? Do you have appropriate corner placement of the Klipschorns? What room treatments (sound absorbing material at strategic locations) do you have in place to dampen reflected highs? Have you employed anti-vibration/anti-ringing measures (for example, many have tried to dampen the metal horn with rope caulk)? Do you want to keep the "stock" Klipschorn look, or open to something different (forum member "Cut-Throat" has a pair of the most cool looking, but not stock looking, set of modified Khorns that you can see in his avatar)? It may be relevant to some readers to know if you are a "passive listener" where you are concerned with sound coverage to various parts of the room or the next room or "active listener" where you want to sit in the “sweet spot” for hours at a time. My first modification was to add a swamping resistor to the crossover to allow for mid-range attenuation. I’ve listened to most types of music at moderate levels for a long time without significant issues with my Klipschorns. However, when I really crank the volume in a home listening environment, I realize the metal-exponential horn limitations (although I find it a bit more of a congested/restricted sound rather than piercing). Best of luck in your journey!

I could be wrong, but I thought that the introduction of Alnico V as a magnetic material (developed during WWII?) was the main reason that field-coil speakers were abandoned? I’m curious if the sonic advantages of the speakers referenced above come from the use of beryllium diaphragms or the field coil magnet structure? Interesting how things come full circle. With so many choices, how does a person sift through all the claims for the superiority of ferrites vs. neo vs. alnico vs. field-coil arrangements? I assume that all of these methods of making the magnetic flux allow very different approaches to the design of the motor structure itself and could have an impact on the driver characteristics........ I believe that Dr. Floyd Toole did some work toward defining the qualities that characterize good sound and then tying those qualities to objective, measurable factors (a scientific approach to listening tests?). Seems like ultimately the measurements have to work in a planned project, then some type of A-B testing (without knowledge of which one is being listened to - best case) with recorded material (or memory of the live performance?) a person is very familiar with to know what is correct (or "best") in that specific situation.

I picked up four old Heresy cabinets awhile back to match with an old Marantz 4270 four channel receiver as a project system. I did the quick modification for the crossover network with the single resistor in parallel with the K55 mid-driver. I ended up only moving the mid-driver from tap 2 to tap 1 and left the tweeter on tap 3 (moved it back to 3 after listening awhile on 2). In my application all four Heresy speakers have the Crites CT-125 tweeters and this configuration seemed to provide the most balanced presentation of music. Overall, I believe that it is a good modification and do not plan to change it back to stock. Also, for those looking at both schematics, in addition to the inductor added to the mid-driver, there seems to be a capacitor value change (2 uF to 21 uF?) on the more extensive modification.

You have to be careful of ARC numbering on preamplifiers. I believe that the SP-8 was the intermediate offering with the high end offering coming later and being the SP-10 (which some consider the holy grail of tube-based preamplifiers). I have not heard the SP-8 (I have heard the SP-11 and LS26 extensively), but I do hear it is an excellent preamplifier, especially if you are looking for more of the “tube” sound vs the “analytical” sound. Also, I believe that the SP-8 has an excellent phono stage. Another benefit if I remember correctly is that the SP-8 MKII uses: (2) 12AX7 LN, (2) 12AX7, (2) 6922, (1) 12AT7, (1) 12BH7, for which the 12AX7 & 12AT7 are much easier tubes to live with and refine the sound with NOS tubes. The SP-9 would be the intermediate offering with the high end offering at the time being the SP-14. I believe that these were more of “hybrid” type preamplifiers with solid state rectification. Today ARC has the LS26 as an intermediate offering with the Reference 3 being the high end offering. In general, I believe that the ARC SP preamps made in the 1980's were fine then and now, and are still fully supported by ARC. However, they all have different sounds, but all seem to come with excellent phono stages, and give up little to today’s preamps other than a bit of resolution, for which they make up in tonal balance, mid range bloom and their ability to throw a huge soundstage. They are not cold and acerbic as are many modern preamplifiers. I’m not sure you could find anything in the under $1,000 category today that could compete with the SP-8.

I believe the K-34 was the stock Cornwall II woofer and that the K-44E may have been the Pro 15 inch woofer rated at 250 watts RMS.

To say it another way, I believe that ALK may be saying that by adjusting for a narrower bandwidth on the bass bin, the efficiency of the bass bin within that bandwidth increases and we can reap output gains that make the gap less between the woofer and mid horn. However, I'm not sure how the efficiency equation actually works, but we could potentially boost bass sensitivity for a better match to the upper range with less attenuation of the mid.

I’m the one having ALK design the ES300 because I believe that on my Khorns that in the mid-bass region there is an inability of my Khorn bass bin to hit 400 Hz cleanly and smoothly. I believe this to be a function of the way the bass bin was designed and you can only get so high frequency response out of it. Also, to me there seems to be a drop off and a ragged response starting out about 200 Hz upwards. Since I believe that my Khorns don’t quite make it up to the 400Hz crossover point there would seem to be a potential hole in the vital high bass/lower midrange region and a good reason to crossover at a slightly lower Hz (i.e. 300 Hz). Subsequently I’ve read so many positive opinions regarding the BMS-Mid 4592 drivers (including opinions outside the Klipsch community when used in DIY projects) and it seems that a 300Hz crossover point with the large V-Trac horn, and what seems to be a truly capable midrange driver in the BMS4592 would mitigate this potential hole in the high bass/low midrange region. Since I’ve now invested in the V-Trac/BMS-Mid 4592 driver combo I would rather have 300Hz and up coming from a high quality compression driver than from a bass bin with apparent limitations around 400 Hz. It may not be for everyone, but I hope that helps clarify.