DavidF

Second mustang guy's response. A crossed wire or short, could hit the woofer with a DC jolt but not the mid an tweeter since they have a capcitor blocking DC. Have to admit I have been careless like that. I would add that my preference is to recone both woofers. The tolerances could be quite different in a cone produced decades ago with one produced recently.

Are you considering buying them? Then no, no ehancement at all. Could there be some benefit in porting the box? Possibly as means to lower pressure in the box at high SPL.. As in a PA application where the low bass is passed off to a sub.

It would be appropriate in a sound reinforcement application. The high end horns are directional and the need may be to get them up and over the crowd so everyone has a line-of-sight reception of the sound. Per your question the idea might be to keep the woofer low on the floor for boundary support but move the high end up a little for a higher sound stage image. At first I thought idea sounded a bit extreme for “what benefit?” Then on second consideration I had to think more about it. One of the reasons I dislike the Heresy on the floor is the effect of the low image it creates for me. I prefer the image at eye level or even a little higher. Just me. Assuming that is the goal you could mount the drivers up on a frame and aim them such that they “focus” along with the woofer on a point near a listening position. Unless you sit quite far from the speakers I fear that the overall image will be seem a bit confused. The woofer responds well into the midrange and so you will have a human voice (among other sounds) coming at you from the floor and from somewhere higher up. Pulling the drivers and covering the horn cutouts could be done so it is reversible.

Using a bi-amp or tri-amp with an outboard filter before the amp has a lot to recommend for the additional cost. Removing a large inductor from the woofer circuit. Removing any interaction of the driver impedance from the filter’s response. Significant reduction of amp distortion under high power conditions. Generally speaking though, the cost may be high for the perceived benefit. Really depends on your application and needs. Another thing is that generic filters do not allow for specific response characteristics that the original passive design either offset or compensated for. For instance the diffraction effect of narrow baffles. Or the rising response of a woofer. Or the falling response of a mid horn. It is fun to try a different approach but I would suggest taking some time for consideration before ripping out a well designed passive network matching all drivers into a well-balanced system and replacing same with a one-size-fits all filter.

Damped –line systems use a material to increase the damping effect of the line. A material such as treated lamb’s wool or poly fill is typically used. The strands of the material create friction that damps the sound wave. This performs a filter effect to pass lower frequencies and damp higher frequencies. Poly fill has a tendency to settle over time allowing the fibers to bunch up. This negates the friction effect. Lamb’s wool was often used because the fibers did not have this tendency and provided a more consistent performance over time. Specialty poly materials are now available that avoid the settling issues. The use of damping material in reflex or ported systems is more to reduce the effects of standing waves. The material does not have to be attached to the walls but this is the conventional method. One of opposite walls or all walls are covered depending upon the need. Plain old fiberglass is one of the best materials for this purpose as it is readily available and can be easily applied. Acoustic foam is likewise is easy to install but generally not as effective. Poly can be used but it is difficult to use for lining the walls. A fill material in the open enclosure can be used in a reflex/vented box to help tune a system or alter the enclosure Q factor. This would have a similar effect of using a resistive port.

I would look at the upgrade path with the source first. Since you are familiar with the computer as a source and likely have a library of digital music it makes sense to start there. A Digital-to-Analog (DAC) converter is the likely first purchase consideration. I don't have a specific product in mind but something that can handle the FLAC and WAV conversions and interface connection has the correct interface type depending on the outputs from your computer. Next I would look at a good quality but modest two channel integrated amp that can be had relatively inexpensively on eBay etc. For a limited expense you could get a hugh improvement in sound.

What provoked me to sell off my gear was the diminishing support of the hardware and increasing difficulties in finding new tape stock. These days I imagine the prime driver is seeking a deck to play back pre-recorded source that is dubbed from high-speed source high up in the recording chain. I had a chance to hear such a recording at a recent audio show and it was a joy to hear. So for this you will need the most-used format. I am thinking 15 ips and quarter inch but not sure if 2 or 4 track is commonly used (4 track is bi-directional). Dubbing vinyl source to tape is handled well with quarter-inch, quarter-track track at 7 ips though you will get a little more headroom with either 2 track or with 15 ips. 10 inch reels are likely what you will ultimately want for practical reasons. Then, too, the image of the 10-inch reels. That comes down to where to source tape stock and getting service on parts that wear like heads and pinch rollers. I have not kept up on challenges involved.

When I have changed compression diaphragms and standard dynamic dome diaphragms I apply a test tone around 1k HZ as I tighten down the holding screws. As with all bolt/screws it's only necessary to tension the bolt to hold the piece. I tighten the bolts on a cross pattern and take each both to "just tight" as I work around the pattern. After all are tightened I use a full sweep of the tone generator and listen for any raspy sounds or obvious distortion.If you over tighten one side of a driver assembly you will notice the coil in contact with the gap. Loosen the bolt or tighten down on the opposite side and the coil will true itself again.

The same as with cored autoformers and amp transformers, I wonder?

You are convincing me! Adds to the clean lines of the woodworking and likely makes the enclosure appear smaller than it is.

Sure, count me as one interested out here.

Disclaimer is that I have not read the thread you mention. The answer you seek may be hard to nail down since it becomes how far you want to go in terms of cost and benefit. I use the Erse laminated coils as the best compromise of cost and very low impedance. A North Creek 10 gauge at the cost of $160 each or an Erse at $23, both about 0.2 ohms. I cannot justify the added expense. On the other hand if I operated at very high sound levels I would be forced to reevaluate. Laminates are OK up to a point until saturation becomes a real problem. So if high sound levels are in play and minimum impedance is the goal then the expense for low gauge air coils has to be considered. Then again at this price point the idea of biamping should be considered with the added benefit of no inductor at all to limit amp damping on the woofer. If you are going to invest serious money to mitigate the effect of inductors why not eliminate them altogether? So for me it does not make sense to spend $300 plus on two coils.

I bought a Kenwood KA-7100 I think in 1978. Lot's of dough for a college kid. Dixie HiFi for about $270. It was the first "real" hifi gear I owned. My Knight tube amp was dying. Piece by piece I added some equipment to match up with the amp but I could never get enough funds to reach out for Klipsch until a number of years later. But I can still remember bringing home that amp and spending an afternoon just looking at it...before I even had it hooked up to anything. You know what, I still have it. For no other reason than it was the beginning, perhaps. Someone will likely chime in and say "too bad you didn't keep that tube amp".

This publication has been the most complete and concise I have read. http://www.amazon.com/Loudspeaker-Design-Cookbook-Vance-Dickason/dp/1882580109

Edited for duplicate posting.

Back on the point of impedance. The impedance rating of the system takes into consideration the minimum values for the entire system. In this case both the high and low. Another way to look at it is if the amp won’t handle the high section or the low section individually, it won’t handle the system, either.

I have not used the Cambridge amp or heard it. I believe your friend has a good idea though, if a quality integrated amp is a direction you are thinking about. At this budget and with high-sensitivity speakers it does seem the way to go. Cambridge is pushing out new models and this an opportunity to save on some well-regarded products. The pre outs allow you to go with a higher power amp down the line some day. Not sure you would ever want more power with the Chorus.

here's Klipsch's take on bi-amping and/or bi-wiring with their speakers. http://forums.klipsch.com/blogs/andyw/archive/2007/09/07/bi-amplifying-or-bi-amping.aspx Thanks for posting. Andy W. is an engineer at Klipsch, then? Not sure the connection with Klipsch. I agree on the overall message that passive bi amping has limited benefits. Mixing "sounds" of amps is a common theme but then you have to deal with different gain between the amps and be sure they are the same polarity. I have two amps that have bridge circuitry included to use as dual monos. I also use them stacked in stereo for passive bi amp specifically to alter the balance gain between high and low sections of the speaker system. The NAD preamp used has a potted output useful for this purpose.This alignment may also provide higher current overhead in the woofer section when I use JBL woofers. These units seem to soak up all the grunt the amplifier wants to give. I can't think of any other advantage as Andy mentioned.

Glad to hear the old Dual work horse is still giving service after all these years. It is a good unit for full automatic operation if its still in good working order. I have an appreciation for Duals of this era. VTA is likely a hard to find feature on lower cost tables these days. The Dual 704 and 721 of the same era had this feature but it was really intended to be a one time adjustment for different cartridges. Not good for adjustments for each disk you play. As I think about it, your concern about using thicker platters assumes your current set up is spot on accurate. Is it? I for one wouldn't know how to go about aligning the tracking angle.

No, I think you may be coming to the wrong conclusion about the impedance. You don't sum the two individual driver impedance to get the system impedance. I would not anticipate you would have any problems driving the high and low drivers with different amps from a electrical point of view. That said I am not sure what your goal is by doing so on this two-way system.

That model SL 5818 looks like a unit I have used. I just can't find it at the moment to compare. Anyway I wanted a non-weighted operation as opposed to A or C weighting so I did not have calculate the curve delta to get a flat response. I believe this unit has that shown as "Lin". You will have confirm. Also, the claimed variance at 1.5 dB is better than most in this price range. In fact I paid around $125 if this is the same or comparable model. Agree with comments on Radio Shack models as mentioned above. I have had 3 or 4 over time and found that they are not very consistent. The older ones seemed to work best but no idea how to tell which are the older models. You will need a test signal generator or something like the Stereophile test disk. I bought the Parts Express Omnimic not to long ago and so far so good. Easy to set up and provides information much more efficiently than a meter and signal generator alone can do for you. $200 more plus mic stand is the added cost but boy what a time saver.

Hopefully we can agree that the Heresy line of speakers is, and has always been, a modestly priced system with compromises in design and manufacture that are understandable given that modest price. That the system performs in many ways above expectations due to its modest design is noteworthy. The original design by PWB had a specific application in mind and he used parts and components available at the time that fit with this design preferences and philosophies. The sound of that original design has become a standard, if you will, that all later production revisions and component revisions had to emulate. To suggest that there is some failing in the design can be tricky especially if we presume an informed compromise to be a design failure. There can always be criticism of chosen compromises since one user’s preferences can differ from another’s. This difference in preference is what drives many of us DIY types to tinker with the product. Since preferences are often expressed in opinions then we should be willing to accept someone else’s opinions. In return we should also expect opinions to be challenged. The stronger the opinion, sometimes, the stronger the push back. We see this a lot in politics and audio forums. I share many of the opinions of the Heresy that Antone has expressed in this thread. I have read with interest what he doing and trying to accomplish. He openly states that his modifications are not based on any effort to commercialize his design but rather to share with others what he finds has worked for him. When Antone says something like this, however, “You're right. Taking a Heresy and modifying it to the extent to which I've done means it isn't a Heresy any longer; it's an IMPROVED Heresy” well, I am thinking that is going to invite a challenge. I would say that Antone has a modified Heresy. Are his modifications an improvement? They sure are to him and it’s hard to fault him for what he experiences. But if they do not hold to the production standard Heresy sound Klipsch has strived for decades to maintain and uphold are they still a Heresy? Simply, no. How can they be? It’s not like Klipsch hasn’t looked at an “improved Heresy” over the years. It’s just that they called it something else. Like Forte. Or like Tangent.

I have the Hersey II. I do not like the overall sound with them on the floor, against the wall. As you mention they sound boxy, or rather the imaging suffers. Also, I do not like the impression of sound coming from below my sight line. My issue to bear alone, of course, but still not my preference. After changing the position around the room I found they image best out away from back wall, mid horns at about ear level, and near the side walls. A sub fills in the bass but there is still a high end tilt that leaves the low mids and upper bass thin. The only cure there was to rebalance the mid/high to pad down the response about 3dB. In the end you no longer have a truly original Heresy configuration. I am convinced that the upward tilt to the response I hear is purposeful in the original design that assumes near-boundary positioning against wall and floor. In this position the bass diffraction is mitigated and you get a more even response from upper bass up through the high end.

The gist of your questions may be what to expect if you go with different diaphragms for the mids. Different diaphragms will have differing frequency responses, yes. So the question then is how much of a difference? I have not seen comparative response curves or heard, say Bob’s diaphragms v. stock, to state how much. The horn does play into the frequency response certainly. The frequency response output is a combination of the driver’s response and the horn’s effect on response. Horn systems that extend down to 1k Hz or so typically roll off around 5 or 6k. As frequency rises the mass of the driver reacts with the horn’s resistance to roll off response by 6bB on average. Different drivers will have different characteristics in combination with the driver and horn. I find that the Klipsch K61 mid will show roll-on roll-off “knees” in response at about 900Hz and 5k Hz. I don’t know how the different specs of a diaphragm will alter the sensitivity in a given driver/horn combo. I suspect not much for practical purposes and would not be concerned about it in swapping diaphragms as you are considering. The stock midrange Forte xover (as an example) uses minimal electrical filtering and instead relies heavily on the acoustic response of the horn/driver for response filtering. Therefore a change in diaphragms could have a noticable effect on response but whether the result is a negative, positive or otherwise I will have to let those who have used them answer this question for you.

You've got a frikin drum set in the house and your mom only complains about big box speakers? Hmmmm. The drivers and cabinets look like they are in fine shape, modifications notwithstanding. Well cared-for perhaps.