Jump to content

PrestonTom

Regulars
  • Posts

    4127
  • Joined

  • Last visited

2 Followers

Profile Information

  • Gender
    Not Telling
  • Location
    New England

Recent Profile Visitors

The recent visitors block is disabled and is not being shown to other users.

PrestonTom's Achievements

Forum Ultra Veteran

Forum Ultra Veteran (5/9)

917

Reputation

  1. Enough about hints and modifications. This is a Garage Sale thread so let's get back to the classified ad (please remember to be respectful and do not pollute a Garage Sale thread with off-topic stuff - you can always start your own thread in the Technical / Modifications section) So Gentlemen, you have a choice in life. You can either enjoy the finer things in life like my friend here and get some Jubilees. Notice that he is suave, debonair and the man about town (and a hit with the ladies) Or you can fail to get Jubilees and end up like this fellow - living in his Mother's basement and taking care of her 17 cats The choice is yours EDIT: upon further research, I conducted a seance last night (induced by the Pinot Noir that the Women's Volleyball Team from UCONN had gifted me). During that ceremony we channelled the spirit of Paul Klipsch. His spirit, from the beyond, told us It really was remarkable, but it did not stop there. His next words were direct and profound. He said: "I think insert your name here must buy Tom's Jubilee speakers" Forgive the irreverence, but selling Jubilees is never an easy thing to do. I will be moving and homes by the water (my dream) are small and the extra money for extra square footage would be outrageous.
  2. In reviewing what I wrote I see a couple of problems in the background. First, I spent a good deal of time showing the cosmetics. I understand that this approach or strategy is not for everyone. It is meant as an example of what one could do to "make Jubilees work in their home", and perhaps save their marriage. If it gets you off the fence and gets you to decide "yes, let's make this happen". Then by all means go for it. Second, I have listed a couple of modifications and hints that might help others. I think they are worth trying. While I feel the improvements are worthwhile, I do not think they are profound nor do I think they are necessarily new. Since I am ignorant, they are new to me. However the real credit goes to these two guys. I hope that nothing I have said is seen as undercutting their very good work.
  3. Modification: Why the absorption on the "baffle" This has a bit of a background story on it. When I first built my Jubilee bass bins, I wanted to use a smaller tweeter horn. The big K-402 was large and it was expensive and was not always easily obtained. I did not see how I could make it work in my space due to its size. I decided to try the little brother, the K-510 horn (a nice horn by the way). Rather than crossing it at 500 Hz, I wanted to cross it about an octave higher. The bass bin can go that high. Unfortunately, if you cross the bass bin above about 700-800 Hz, the bin's dispersion becomes problematic. The rule of thumb is that the two drivers (tweeter horn and bass bin) should approximately match, in terms of dispersion, around the crossover region. What I mean by dispersion is the angle off-axis where the top and/or bottom roll off about -6dB (broad beam of sound vs a narrow beam of sound). With a bifurcated horn (eg Belle, Klipschorn, or Jubilee), the sound will roll off (more so at higher frequencies) as you move off-axis. This is standard. However with a bifurcated horn it may not continue to roll off as a function of angle. The response may rise again and on a polar plot it will appear as a "petal". There is a discussion of this in the Delgado and Klipsch JAES (2000) paper. There it is couched under the label "splay angle". Is there a way to decrease this "petalling"? Yes, a few inches of acoustic foam on the baffle (in between the two bifurcated sections). When I say foam, I mean pressed fiber glass, acoustic foam or Rockwool (which is what I use). I do not mean closed cell foam, fluffy fiberglas, felt, or egg crate. You need to get the right stuff and 1/2 inch layer will do nothing. Someday this might be a useful trick for some of you. Why the petaling occurs to begin with can be part of a separate thread. Well. later on I was able to get a K-402 horn, but I had learned something with above exercise. First a problem with bass horns. We live in a practical world with living rooms that are a practical size. Horns are effectively an impedance transformer. To make this transform, the wave's impedance must be comparable to the impedance at the throat (small cross-sectional area) and again at the mouth (large cross-sectional area) all this as the expansion grows by a certain function (exponential, conical etc). If the horn is too short or the mouth too small, then the transformation is incomplete and not all the energy is launched into the room, part of it is reflected back to the throat where it may combine with the next wave either in phase or out of phase. Roy sometimes refers to this waveform as being a bubble that is stretched. In a Jubilee the response shows peaks and dips due to the problem above. There are peaks at around 100, 180, and 300Hz and dips around 75, 210, 260, or 340 Hz. The peak-to-trough ratio at around 200Hz is especially severe (around 9dB - the measured severity can depend on the space the cabinet measured in (floor, wall, pair of walls etc). What tricks can be used to decrease this peak-to-trough ratio. There are several a) the closer the Jubilee is to a boundary or boundaries the better. So place the Jubilee near a corner (it will also boost the overall low bass and works with all cabinets in fact). b) DSP, Roy's DSP setting are not just for the crossover. Along with balancing the relative gains, compensating for differences in driver delays, the settings provide high end boost (required for all Controlled Dispersion horns), and they knock down some of the peaks (discussed above). So the amplitude response will then have less pronounced peaks and troughs. c) The last trick is what I stumbled upon. Place a few inches of acoustic foam or pressed fiberglas or Rockwool on the baffle. This will further diminish the peak-trough ratio. I discovered this for myself when I was worried about dispersion with a bifurcated horn. It always pays to do before-and-after measures. Now, do I think that I am the only one that knows about acoustic foam on the baffle of a bifurcated horn? Of course not! However at the time it was news to me. Maybe this will help others also.
  4. Modification: Why the split cabinet configuration A few reasons. 1) The factory configuration (both woofers in a single cabinet) is a heavy cabinet. 2) splitting the cabinet in two allows for extra bracing (although later version of the factory cabinets do have additional bracing). If you have an early version, you can always add a brace to the final flare (it does need to be massive, just well-attached). 3) If you want you can configure them as Tweeter-Woofer-Woofer. This is essentially what the factory version does. When mine are stacked this way, the frequency response and impedance sweep are the same as the factory version. However, the tweeter is above the listener's ears. Whether this is a problem will be a personal preference. It also puts the Tweeter closer to the ceiling and the ceiling reflection is more objectionable. Again this will depend on the geometry of your room and how close you are sitting etc. I found that in a room with a 7.5. or 8 ft ceiling the ceiling reflection gave an audible change in timbre. The effect was not night-and-day, but it was noticeable. Enough so that I changed the configuration and lessened the ceiling reflection. 4) Or you can configure them as a Woofer-Tweeter-Woofer. This is what I ended up preferring and doing. First thing I noticed is that the timbre seemed more accurate or natural. I attributed this due to the diminished ceiling bounce. Although the center of the tweeter is also now aimed at the height of the listener's ear. The other effect was that (for lack of a better word) the sound seemed more "coherent". Interestingly when I looked at the frequency response (amplitude) from about 300 Hz on up there was no difference (between W-T-W and T-W-W). However the phase response (W-T-W) seemed "better behaved" in the octave surrounding the crossover region. I will stop there since trying to equate audible changes with physical changes in the phase spectrum is tricky at best. I will say there is a weird side benefit in the W-T-W configuration. You can actually sit fairly close to the cabinet(s) and still have an "integrated" sound (again, for lack of a better word). I assume this can be understood by "adding up the vectors). With a bit of hand waving - the bass essentially comes from four mini horns (two half-height horns vertically spaced about the tweeter's center and each of these bifurcated horizontally about the about the tweeter's center. -That is a tongue-twister so try and visualize the "center of where the bass is coming from - both the tweeter and the bass have the "same center"). Maybe this why the sound is integrated even at fairly close distances. Note, even "regular Jubilees" have good integration at somewhat close distances. The other thing I noticed, and it was especially true in the smaller room (7.5 ft ceiling) was that the bass was more even and less mushy. The frequency sweeps showed shallower peaks and nulls (in the W-T-W configuration). It is probably not the cure all for all room effects/interactions/problems, but it certainly helped. However, I doubt that it would make much of a difference at the lowest octaves. Importantly, this idea of a W-T-W vs a T-W-W configuration is not novel idea. It has been around for decades. It is usually done so the energy (lobe) near the crossover region can be aimed at the listener. The driver-driver distances are usually much smaller and the spectral regions are usually much higher. I don't mean to sound like I think I invented something new (I am not that much of an ego-maniac). Some of the effects that I "discovered" in this case are interesting and not usually discussed. Discussing these in a separate thread might be of interest (but not this thread please). All in all, I like the ability to stack the half-height bass bins.
  5. Photo 8 These two photos show the side and "inside" of the grilles. With a screwdriver and staple gun you can swap out the grill cloth material. Perhaps paisley, or a leopard skin print, or an air brush of a Native American Brave on his horse with a buxom and beautiful princess. Nah, stick with what I have done since sometimes you don't want a "conversation starter". Remember, you are not living in your Mom's basement with 17 cats. You are the sophisticated guy who is a hit with the ladies. Seriously, In the lower photo (which matches with with the lower half-height bass bin). there is a structure on the side which "completes" the bass-bin-horn-path. The second thing to notice is the luan panel that meets the bass bin "baffle". There is coarse black cloth stapled to the luan. On the other side (facing the room) and under the coarse cloth are a few inches of Rockwool/pressed fiberglass (not the fluffy stuff). This has a couple of benefits that I will detail later. Of course, this is replicated on the top third of the grille also (for the top bass bin). Unless you are trying to show the baffle on conventional Jubilees (where the veneered panel might be), you may want to consider doing this.
  6. Photo 7 Not a very interesting photo, but this what the back looks like. Since theses are in, or near, corners no one will ever see. Perhaps a cat might sneak behind and get a glimpse. Or, if it will help you sleep at night, then a birch panel from the stock they sell at the big box Home Center, can be cut up and bolted to the rear/sides of the "tweeter box". Wipe it down with Tung Oil and you will have a perfect match. Really ..... why bother. The cat won't let out your secret. What is pictured is the big JBL 2445 driver. It is basically a beast with a 30 lb magnet. Of the different drivers I tried, it measured and sounded the best.
  7. Photo 6 This gives a better idea of the tweeter cabinet (minus the K-402 horn of course). It is carrying a bit weight, so I braced it with poplar boards. There is a lip on it where the "rib" on the grill rests. I had intended to augment it with a strip of velcro but found it was not necessary. For those scrutinizing the details, it would seem that the final couple of inches on the horn path for the bass bins has some discontinuities. It does not. I got worried that any discontinuity might cause some whistling (i was over-thinking things). So the edges/sides of the grill where it attaches to the "face" has a small structure to "meet" the end of the bass bin - horn-path (with a strip of foam at the actual junction). All that was done so I could sleep well at night. My words are not very communicative, so the photos later on might help.
  8. Photo 5 This gives a better idea of the side facades (panels)
  9. Photo 4 They can be tucked even tighter into the corners (these are toed-out a bit). Only a spider will see that the sides are not integral cabinets, but rather facades (they attach with 4 bolts in the handles going into huricane nuts embedded in the the "tweeter cabinets". Likewise, the bass bins are also bolted to the "tweeter cabinet" (both top and bottom). So the beast slides around on the base as a "single unit". The base has carpet pad underneath so it easily slides on a wood or tile floor (great for fine tuning the placement and toe-in)
  10. Photo 3 What does not come through in the photo, is that the grille cloth has a linen texture to it, so it does not simply look like a sheet. The fabric of course can be swapped out. Get something thin and stretchy. Mine is a synthetic. It only affects frequency response in the top octaves (about -0.7 dB at 8 khz and is easily equalized). What is also hard to see is that the grille has a gentle curve to it, so it is visually interesting. I chose a color that made the big beast seem to disappear into the wall. The net impact is that when folks walk into the room, it will take them about 10 seconds before they exclaim " hey, there are huge speakers in here" . Wait, did I say 10 seconds? How about 5 seconds, but you get the idea. Believe me, they can be incorporated into your living room. They don't need to be hidden away in the basement. At one point in time (probably after a glass of some refreshement), I toyed with idea of a grille cloth made from a leopard skin print. Perhaps it was just reminiscent of the panties those women I was dating used to wear back when I was in my twenties. Anyway, the choices are endless.
  11. Photo 2 This is a wider room: 12 ft wide and with an 8 ft ceiling. Let me remove some clothing You see that it has a Woofer - Tweeter - Woofer configuration. I'll talk more about the advantage of this later on.
  12. Above are the Jubilees in a room that is 11 ft wide with a ceiling that is shy of 7.5 ft. Certainly they can fit in your house.
  13. First things first. I have carefully chosen my words. These are not entirely factory made Jubilees. That is why I call them ”Jubilee-style”. Bass Bins: They are made according to the details from the Journal of the Audio Engineering Society article by Delgado and Klipsch (2000) and further confirmed by others with hands on knowledge. The geometry of the back volume, throat, expansion, corners, reflectors, mouth and baffle are correct and identical to the factory versions. However, I made these as two half-height bass bins that can be stacked on top of one another. I’ll talk about the advantages of this later on.The frequency response and impedance measures are the same as the published values. The drivers (K-31s) are the same ones used in the factory version. I have them currently stacked (as shown in the photos) as Woofer - Tweeter - Woofer. This has some benefits that I will discuss later Tweeter: The Tweeter horn is the Klipsch K-402 and purchased from Klipsch. Although the stock Klipsch K-69 is a good sounding driver, I upgraded to a JBL 2445 driver. It is also a 2 inch throated driver with a bigger & stronger magnet (For those interested, a JBL 2445 or 2446 can be purchased new with a street price of around $800). Since the drivers were upgraded, the DSP settings on the crossover were correspondingly adjusted after measurements were made and verified. Okay, that is now taken care of and there is no reason for anyone to corrupt a Garage Sale Post by arguing whether these should be called Jubilee-style or not. In this initial post, I will list the specifics for the sale. After that I will discuss some things that I learned along the way that I found interesting and that others might find useful. Since they pertain to this classified ad, I will do this as part of this current thread. If folks want to discuss these issues further, that would be great – but NOT in a Garage Sale Forum. Further discussion would need to be initiated in separate threads elsewhere (probably in the Technical / Modifications Section). Nuts and bolts: The cabinets come with the components listed above. They will also include the cosmetics shown in the photos. If the grille cloth is not to your liking, then a trip to the fabric store can solve that. A staple gun will be your friend. Location: These are at my house in Preston Connecticut (06365). I am in the Southeast corner of Connecticut (near Foxwoods Casino). This is just off I95 or I395 and about an hour from Hartford CT, New Haven CT, Providence RI, about 2 hours from NYC, or Boston. They are currently hooked up so they can be auditioned (source is a CD Player). Price: I am asking $3,300. For the pair. However, If the transaction is quick and simple, then I am willing to knock off 5% to 10%. For those of you who have sold used cars on CraigsList, that is usually something that is not quick and simple – I am looking for the opposite. If someone is interested and wants a plug and play setup, I can toss in a DSP Crossover (Berhinger DCX 2496 either new for $250 or used for $150). I will also include a so called “passive preamp” (6 channel potentiometer in a metal box). The Behringer is nice in that it has plenty of processing power and can accommodate a digital input (AES/EBU or a S/PDIF). I am a believer in using a digital input and having the “passive preamp” after the DSP (since it will knock down any hiss or noise from a processor as the signal is attenuated). In either case, the buyer will receive the settings required for the DSP (mine or theirs). The Jubilees will require an active (DSP) crossover and four channels of amplification. On the lower end are Behringer and some of the dBx, Ashley, miniDSP units, moving up to Electrovoice and Xilica and further up to Yamaha, DEQX, BSS etc. There is quite a spread in price. My hint is that if you can get one with a digital input and place a multi channel pre-amp after the processor, then it should sound pretty good (even with the less expensive units) The factory two-way Jubilees were being sold for about $8.5 k (raw cabinets and no crossover). That price usually included shipping but whether sales tax would be added was ambiguous (my guess is that one can seldom avoid taxes ….). The current two-way Jubilees (raw cabinets no veneer or grille cloth) were still being sold in early Spring, but it is rumored they are no longer available (probably not relevant to this Garage Sale thread so let’s not digress). I only bring this up as a point of reference. If you are seriously interested, please PM an offer. Let me note what an offer should consist of. First – When and how you are going to AUDITION them. Second – When and how you will PURCHASE them. Third – When and how you are going to TRANSPORT them from my place to your place. Please think about the details on your offer. It will help me decide on whether the transaction is “quick and simple” and worthy of some sort of discount. Let me tackle the usual questions before you PM your offer. NO trades NO, I will not deliver them NO checks of any sort nor paypal. This is cash only NO, I will not part them out These are on a first come first served basis. Whoever pays for them first, owns them (again think of the idiots you meet on CraigsList) The cabinets are modular and be easily carried by two people. They would probably fit in a cargo van (remember the grilles are big) or a box truck (perhaps folks on CraigsList doing side gigs). A SUV would be tricky but I moved them in two trips using a Honda Odyssey. Let me finish posting the photos and tips before you join in. I will get to it tonight
  14. Edgar is absolutely correct. There are problems with the online tests, but it is at the transducer end of things along with the headphone positioning, & adjustment/tracking procedures. The techs and audiologists who perform these tests have a fair amount of training and are using headphones (frequently the clunky looking Telephonics - TDH's) that are rated for clinical use. There are actually a large number of details involved. Not all testing is done as pure tone audiometry (PTA). Some testing may additionally include specialized speech signals (that have a huge database backing up what is considered "normal acuity"). However, the idea of using "everyday sounds because they are more natural", is far-fetched. Testing leads to diagnosis and treatment so the standards are there for a reason.
  15. If the OP is interested, he is about 4-5 hours from where I live. If you have never heard K-402s before, then you are welcome to come and listen to some K-402s (on top of Jubilee bass bins). Perhaps this could be part of another trip to this part of the country. They really do sound terrific. It may even change your mind about the price of a K-402 or going whole hog and actually getting a pair of Jubilees.
×
×
  • Create New...