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Hello Max, I had found that my preference for amplifiers increased as low power distortion went down. The distortion specs. for the TA 2020 used in the KingRex are almost identical to those of the TA 1101B I used in the P6Ds, so I would expect the performance to be very similar. What I found was the Tripath way out performed almost all ss amps available a few years ago, in the region of audio I care about most: low level detail and timbral accuracy. This made sense in that low power distortion of most ss amps at the time was through the roof. Current ss designs may have improved on this to some degree. The Tripath design still had a little grit, which shows up in the good, but not vanishing .03% distortion (and rising) at 0.5W. This predicts the amp has a noise floor and some audible distortion and listening bears that out. There is also some interaction with Tripath PWM and speaker at high frequencies. This never bothered me, but I did go for an output filter that was optimized for an 8 Ohm tweeter .. maybe that helped. I moved on to no-feedback tube designs because they handled low level detail better and were even lower in grit (I would presume certain types of distortion) than the Tripath. The Tripath does have an op-amp input stage and the grit may be typical feedback and/or crossover noise. I picked up a Crown D-45 because its low level distortion was an improvement over Tripath and it offered better damping which I wanted for the Chorus-II. This also worked as specs predicted: damping got rid of the mid bump in the Chorus with no-feedback tubes and the low level distortion was on a par with the tube amps. I was attracted to the Hypex because the low level distortion was over an order of magnitude better than the Crown and it retained or improved upon the damping at all frequencies. Additional power was a bonus. Again, performance is as the specs predict: big improvement in low level detail, vanishing distortion (I have yet to hear any), and total control over the speaker. I am interested in what it was about the performance of your Hypex amp that you didn't like.

Hello Max, I wasn't aware of this Tripath implementation. I'll read over the reference and get back. There are a few details I want to check. Thanks, Leo

Hi Marty, Good to hear from you. The Hypex amp is such an improvement over any of my other amps, I'm not sure what my next move is. The Hypex is currently on the RF-7s replacing the SETs which had been the amp of choice. The Hypex sounds way more realistic and natural. I have yet to hear any distortion at all .. I mean this thing simply doesn't screw up. And there is much more dynamic capability into the lower amplitudes: hall ambience is much more meaningful. I can clearly hear echoes from side and rear walls. Images are 3 dimensional and rock solid. Differences in media are more obvious: records often handle sibilance better (cd isn't distorted, just doesn't seem to be all there .. maybe it's the player), but CDs have much more dynamic capability (again, here I'm referring mostly to dynamics into silence, not high acoustic power). Violins (single and massed) are soooo nice. I'm going to try the Hypex with the Chorus-IIs next. Really, I was wondering this morning if I was simply going to stop listening to the other amps entirely .. they just sound so flat and 2-dimensional. I'll keep the Tripath amps for various portable applications. I don't know why there isn't more interest here except Hypex is not the lowest cost way to go (although it may be the lowest cost way to get such low distortion at low power), and I'm not sure that many people buy my proposal that low distortion at low power is the road to audio bliss. Building a good Hypex application takes a little skill. I think the cheapest commercial application is may 2 grand .. lemme check: CI Audio does make the D-100 .. this might use the same module. With my usual fear of trading low power clarity for higher power I would go for the -100 rather than the -200. Music Direct seems to sell a pair of D-100s for $1599 .. I might pick up a pair if the improvement with the Chorus-II is similar to what happened with the RF-7s. I had just completed an upgrade to my PP amps and was so happy with them until I completed the Hypex. Again, good to hear from you and I hope the holiday season goes well. Leo

There are a few pictures at this site: http://picasaweb.google.com/martha.creedon/Amp# The amp module on the top shelf contains power caps and the Hypex modules. DC enters one side and audio I/O is on the far side. The AC/DC and softstart module is the larger cabinet on the lower shelf. AC enters one side and DC exits the other. The cable is 7 14awg wires shielded and covered with a plastic mesh. I made no effort to have it look nice because it will eventually be located completely out of site.

I agree: two Tripath lessons. In my Hypex amps I use 10,000 uF (4 total) low ESR supply caps with 5uF polypropylene film caps in parallel connected to the amps with 12 gauge wire under 2" in length wire. The design is completely dual mono, with the two amps sharing only the power cord and initial line rf filter. An interesting thing about the Hypex approach is it IS a global feedback design and so it has supply noise rejection. What's different about the feedback is it doesn't drop off as the signal gets close to perfectly linear. Instead, it produces a relatively constant, high freq. dither around perfectly linear with the error pushed above the audio bandwidth. Leo

I may have made a mistake and buried this in an old thread that had irrelevent baggage. For people who ar looking for an amplifier that will provide a natural sound with Klipsch speakers, lack of harshness and plenty of dynamic depth: I have spent considerable effort in trying to achieve the same: and I don't have a product to sell. My signature lists several previous efforts. My latest effort has used the Hypex module mentioned below. I find the Hypex approach to be unique in its effectiveness in reducing low power distortion: it is not conventional Class-D. Several off the shelf amps are available using the Hypex modules and for someone looking for very low distortion, natural sound, they should be considered. Following my entry in the older thread: I finally completed the stereo amp based on the Hypex UcD180. I took all I'd learned from the Tripath experience and put it into the design. I'm satisfied. It blows away anything I've heard. It also convinces me that the key to good sound is low distortion at low power (<.03% THD & noise at 10 mW). Nice to have that clean low power in an amp that will deliver 30W (I kept my design as low power as possible). I don't have any further plans for audio upgrades, but really wanted to finish that amp. I'm doing a lot of listening now. Leo

kdonn, One thing you said may impact the decision: "The bipole design really throws a lot of sound out the back and in my current room, that means out the door .. " I think that means you want a speaker with no rear-firing elements. Do the RF-83s have rear firing ports? If so, some of the bass will be going out the door. The La Scala and Cornwall have all front firing elements and so do a several other Heritage and non-Heritage designs. Leo

MrWhite, What I am refering to is not a matter of frequency response (as in brighter mix). I am refering to distortion which is a different matter. Distortion generally takes the frequencies that you should be hearing, creates various nonlinear mathematic "cross products" which are not the frequencies you should be hearing, and adds them to the signal that you finally hear. Since the "s" sound is a type of filtered noise, when the distortion adds additional crossproducts of that noise (also a type of filtered noise), it sounds like it might be a louder version of the original caused by equalization enhancement. But it contains frequencies that were not in the original "s" sound, and even if an equalizer or tone control is used to reduce its volume, it will still sound grating and wrong. I've heard plenty of Dolby Digital encodings that sound distorted. To some extent I attributed that to my HT equipment to which I pay very little attention. Maybe Dolby Digital is distorted. Possibly the distortion is added so that the sound has a familiar "electronic sound track" sound that people are familiar with. Often, with undistorted sound, people think there is something "missing" from the high end, and they claim it has "no slam." Distortion definately adds "slam." If CDs really don't have this problem in your system then you may be dealing with a HT equipment or presentation issue about which I know nothing. But that would be a good thing because it limits the scope of your problem the the HT sources. Wire would not cause the problem you describe. Connections in general might, but if you "wiggle" the line connectors and things don't change, they're probably fine. http://catalog.belkin.com/IWCatSectionView.process?Section_Id=202495 Good luck, Leo

What I think you are describing is the exaggeration and general trashing of sibilances ("s" sounds) that is the result of various sources of distortion, most of which are probably not your RF-7s. I have RF-7s and know how revealing they can be of system distortion. I also know how delightful they can sound if you can eliminate the sources of distortion. Some sources of distortion: Many amplifiers, especially solid state, have very low distortion, as a percent of the signal, at high power but very high distortion at low power. Even listenting at very high levels, sibilances are very low power sounds, but also very complex (a kind of tuned white noise). Guess what distortion of noise creates? More noise, and not the right noise. So sibilances are the canary in the coal mine for low power distortion. Klipsch speakers are especially vulnerable to low power distortion because they are so sensitive and use so little amplifier power. Another distortion source is radio frequencies getting into the audio system through the power lines and mixing with (actually modulating) the audio. Guess what modulated noise creates? Another possibility is clock jitter in digital to analog conversion, another source of signal modulation. Another possibility is dielectric absorbtion in inexpensive crossover caps (which is one reason many Klipsch speaker owners, including me, upgrade the caps in the crossovers of their speakers). However, If you clean up the amp, the digital source, and the power, the crossover cap contribution may not be significant enough to bother with. The amp (and preamp) is a tough problem. Personally, I don't think just going to tubes is the answer. I think the feedback in many tube designs has its own characteristic noise at low amplitudes (which is why my tube amps are both no feedback designs). You might try an inexpensive PWM "digital" amp to see if there is some improvement in the sibilance reproduction. PWM tends to not trash sibilance and is a good way to determine if the amp is a significant part of the problem. A good power line filter (RF filter, not spike protection). Spike protection is fine, but it won't help with RF modulation. Belkin has a few good line filters for around $100. I have an old Philips 963SA (with power supply mod to reduce noise) and another system using an old Sonic Frontiers "TransDac." With various mods they have become very well behaved. I don't know anything about the Oppo DV-980h or the other sources you mention. Although I am happy with my stock Crown D-45 on the Chorus-IIs, I do prefer the SET and even the small PWM with the RF-7s. Good luck, Leo

The area of the two smaller "woofers" in the RF-52 is close to that of the single "woofer" in the RB-81, so "impact" should be similar. Horns are the same or very similar. I'd go with the RF-52. Leo

If you can configure whatever amp you decide upon to a 4 Ohm output, I suggest you give it a try. It provides more current for low impedance regions of the speaker's frequency response and is less likely to peak in the high impedance regions: smoother frequency response and lower distortion. Leo

I remember Electrovoice seperates (amp and tuner), each about the size of the Parasound Zamp. I guess they made a receiver version. Possibly they were trying to address the mess most ss electronics made of their speakers. Interesting you like the sound with Cornwalls. Leo

I wouldn't miss it. He was in Boston a few years ago, did a version of Highway 61 Revisited that I'll never forget. It took me several numbers to figure out what he and the band were doing. After that it was all a lot of fun and, for me, excellent music. One frustrating factor is the volume was too high for me, and I had to wear ear protection. On the few quieter pieces I removed the protectors and was impressed with the great sound of the band. I'm sure it was just as great loud, but my hearing distorts at such levels so I'm better off with the protection. One thing that was interesting: the lead guitar (not played by Dylan) used what I think was a Fender amp with a very large horn loaded hf driver. Possibly it was a custom design. I wondered if possibly the reason that guitar sounded so good is I was hearing it directly, not through the house amplification. Maybe at The Brady you'll get mostly direct band sound and not secon generation stuff .. that would be nice. If you go, I'd be interested what you think. Leo

Hello John, Yes on both. It's interesting looking back, because of all the equipment I auditioned and purchased from those locations, none are in my current system. Only the Klipsch products have remained constant. I replaced the Forte-IIs with Chorus-II, and added 2 pairs from the Reference series, but the Klipsch equipment (with a tweak or two) holds its own as other system elements are improved. Leo Oh .. I take that back: a used Sonic Frontiers "Transdac" which I purchased at Natural Sound (and then tweaked a bit) has also remained constant. I would also still be using the Magnum Dynalab FM tuner from Natural Sound, but classical FM is gone from my location.

The Music Box in Wellesley is where I purchased my 1st Klipsch speakers: the Forte-II.

Hmmm, I don't call it a P6D in my signature below. The P6D is the Tripath based amp I built a few of several years ago (Pulse width modulation, 6 Watt, Demo). On the capacitance, I'd check the Denon specs. I think they just say >100 Ohms. Maybe someone else has something to add concerning how one might optimize loading of a MC cartrige. My tendency is rather unimaginative: I read the data sheet and try to do what I read. Leo

Well, I was really thinking of going directly from 47KOhms to something like 2.2 or 1 KOhms (replacing the 47K). Output impedance of MC is very low. Your take on the intent is what I have in mind. I haven't been to DC since the last time Martha and I stopped by. Since then my brother has picked up a pair of Forte-IIs. I'll be down sometime to upgrade the crossovers. Meanwhile he's quite happy with the Fortes and one of my P6D amps. When I make the trip I'll see if we can arrange something, maybe with a concert at the Strathmore PC. Leo

Have you seen: http://www.stereophile.com/phonocartridges/1207zu/ The Anthem claims to handle 0.2mV devices (Hi gain setting) and the Denon has a 0.3mV spec. so I would expect it to work. The 47KOhm input resistor on the Anthem certainly meets the >100 Ohms Denon requirement. Trying a bit lower (1KOhm, for example) might tighten up the sound a bit. The Anthem instructions mention possibility of changing the load resistor. You or someone may have added a capacitance to the Anthem phono loading for MM and, if so, I think you might want to remove that for the Denon. I think I modified my Creek to no cap and 1KOhm or 2.2KOhm load when I changed from MM to the Benz Ace. Leo

Hi Chris, Good to hear from you. I have some very patient neighbors (of course they don't care when the screwball groundskeepers at the establishment across the street run a team of leaf blowers at 10:00 PM). I tried the sweep trick on the RF-7s one Sat. when Martha and I were working in the yard. It was tough to ignore. After about 15 minutes and some "You gotta be kidding me" looks from Martha I shut it down. I only lasted that long because I was curious how long she'd last. I don't know why the neighbors didn't call the police or at least say something. After that I learned the out of phase trick. I hope the spring is going well for you folks, Leo

Creek - OBH-18 MM Phono Preamplifier. I use a high output Benz ACE MC. O changed the Creek input impedance to match the Benz requirements. It's discrete, class A. Sound has always been good. Leo

Hello Wilson, To very effectively break in a pair of RF-7s I used a sine sweep, 20Hz to 20KHz, loud enough to want ear protection when in the room with the speakers. I repeated the sweep cd track for 2 days, about 10 hours / day (20 hours total). If you do this, be sure the amplitude of the sweep reduces as frequency goes up so that the high Freq. horn is not damaged. Leo

Hi Chris, Wow! Dallas. OK. Well it sounds like Dallas is working out, and I'm sure a lot better when Carrie and Jack are there. You do have a sonic impact and we tried it here. Please let people here know how the power supply works out. If you have any issues let me know .. I've probably seen them. It's not that the application is all that difficult, there are just several variables to supply matching. Don't forget to order the power cord. Leo

I can't seem to enter line feeds so for clarity I'm adding this post. I didn't download the datasheet because it was too big. I did download some info on connectors. It's the attachment in my previous post. I don't know what the Sonic Impact uses, but the attachment shows there are lots of options. Take a look at the web site I listed, also in my previous post, for info on the stock connector. The datasheet can also be accessed from that website. Aren't power supplies fun? Leo

Hi Chris, Good to hear from you. I hope life on the island is treating you well. I have a few specs on what looks like a close match. I couldn't find the exact one I used: Power Supplies Unlimited, Inc http://www.psui.com/cgi-bin/shopper.cgi?defaction=search&keywords=trg36 TRG36A12-21A02 30W Energy Star Compliant 12V@2.5A Desktop Adapter - Cincon 16-00601-00 power cord I'll try to add datasheets to this post after I check them out. Some things to be considered: I don't know what kind of filtering is available in the Sonic Impact and I don't know how they have implemented turn-on mute. There may be interaction with a supply that has to be worked out. In my P6D for example, The large output power capacitors were so big they looked like a short circuit at turn on so I had to build in a soft start. That's why the P6D had a delay when turning on followed by a click. I also did some tweaking of the mute, but can't remember exactly what was involved. Anyway . .I'll get the datasheets on the supply. Leo adapterpartno.pdf

The supply I used was a 12V regulated switcher. It was off the shelf but I had a small custom run built with the connector of my choice. I'll look it up and see if it still exists. Leo