leok

Hello Chris, I use a Creek OBH-8SE preamp with a Grado Gold cartridge. I consider my equipment entry level but very enjoyable. The Creek does not use op-amps, and I think that's important. In the Feb/Mar 2002 Absolute Sound there is a review of a "Gram Amp 2 SE" that goes for $220. That's interesting. My turntable is Dual CS 431, and I would suggest you get something better. Still: from the Philidelphia Orch. doing Bartok's Concerto for orchestra, through Nick Drake, and back to Judy Collins' "5th Album" that modest equipment sounds beautiful through tubes and RF-7s. No-feedback amps and records are especially nice. I give real dirty records (that I've picked up at a used outlet, or from my father) a bath with warm water and mild dish detergent. I use a series of disk brushes to wash and then rinse, and then rinse, and then rinse ..shake, then damp-dry with soft towel. Next is isopropyl alcohol (the lower % variety), which I apply then dry with different brushes. The alcohol will absorb remaining water. Next is Last Record Preserve System Formula 2 (this is where I ave gotten all of my brushes over the years). Be sure to mark records that have been treated because the treatment lasts for 200 plays. I clean the needle with Last Stylus Cleaner System Formula 4. and then apply Last Stylus Treatment System Formula 5. Then I play the record. Subsequent playings involve a quick brush with isopropyl alcohol then dry (both with the record spinning on the turntable, and stylus cleaning and lube. The bath can be skipped for new or reasonably clean used records. I can say that each of the above steps makes a positive difference. Don't tell anybody I do all this when I play records. Kelly, congratulations on the house.

I have experience with two older tube amps: One is the Heathkit W5M. It's mono, so you have to buy two. Also, it may require a fair amount of work to restore. But the transformers and HV choke are very good. It uses 2 KT-66 output tubes in ultra-linear config. Preamp tubes are 12AU7. They're all easy to obtain.The 5R4GY was a little harder to find, but not expensive. I used it on Forte-IIs and RF-7s. It has plenty of power and wonderful sound. I say "used," because I like to rewire it to try different tubes and configurations. Right now I have it wired as triode mode push-pull using a single 12AU7 as gain and phase splitter. I like it that way a little better than straight SET because the KT-66 really isn't so great for that use and I'm not sure that's a real good use of the transformer either. This week I hope to get a pair of E88CC tubes, which are a lot like the 12AU7, but more linear. I mention all of this because, if you like to experiment, the W5M is a great platform. The other amp I've tried is a Dynaco ST-70. It had an upgraded preamp section and had a very impressive sound. This is a slightly more modern EL34 ultra-linear design with plenty of power. I think there are a few more of these around, they're stereo, so you only need one. Very nice amp. It might not lend itself to tinkering quite like the Heath, but it's easy to work on. Additional notes: The Heath is pretty much a triode design and lends itself to no-feedback mods. The Dynaco is more pentode-oriented (initial gain is pentode and I don't know how well EL34s do in triode mode). No-feedback might be a little difficult whth the Dynaco. But you could just leave it alone and listen to it. Both amps are great with Klipsch speakers.

That's an offer I can't pass up. Let me see .. I could spend the next seven or so years trying to figure this out by myself, or check a few recommended references. I choose the second. I'm real interested in any references you care to share. Meanwhile, the modified W5Ms provide great listening with the RF-7s or Fortes. Also, best wishes for the Holidays. leok

mobile, arco, Conductor Based on the above discussions, I tried a few experiments with my 2 Heath W5Ms. The amp is normally configured as ultra-linear with KT66s biased dissipating just over 20 Watts each, at idle. One of my Sovteks died so I had only a set of Valve Art tubes which seemed to lack high frequency capability. I had re-wired the g2 directly to 400V dc to operate in tetrode mode, which is designed to reduce Miller capacitance and improve high freq. response. This worked, but there was clearly some distortion at the high end. Mobile strongly recommended the triode configuration, so I tried it; connecting g2 to the anode. I had expected high frequencies to vanish, but they didn't. Much of the high end distortion also vanished. What was left was some swirly sounding stuff on the "S"s. Mobile even more strongly recommended single-ended triode so I disconnected the signal input to one of the KT66s (leaving it in to balance the bias into the output transformer). This was very good. In fact, this was much better than I would have thought. The sound was cleaner, more articulate, and the swirly stuff was gone. At this point, what I had was very much like a big operational amplifier, with a voltage gain of 10, and a single-ended output. This is a really cool thing and one would do well to stop there. But Mobile also mentioned that single-ended triode with no global feedback is worth a try, and there are plenty of reviews that agree. Also, there is plenty of engineering that agrees. So I removed the first gain stage and phase splitter (which wasn't helping anyway). The results were very remarkable except that the KT66 had absolutely no local feedback and was scrambling the high end again. So I re-connected the ultra-linear connection to give it some negative feedback (why the triode connection doesn't do this is a mystery to me). This is a tradeoff between high end distortion and upper mid. detail. I'm sure this is the starting point for a real single ended triode amp. The point for me is I have never heard anything that comes close to this. I am completely sold: SET is the way to go. This setup has better frequency response, and greater dynamic response than any amp I've heard, and a soundstage that is alive. The RF-7s performed well throughout this excercise, as I'm sure most Klipsch speakers would. What impresses me was if I can get the amp right, the speaker is ready to do it justice. More than ever I believe if you don't like what your Klipsch speakers are doing, it's probably what your feeding them. Conductor, as for your CAV50, If you can check out triode mode, do it. You can always change it back, and you might get a big surprise.

arco, Hmmmm, I wonder what that cap does. But mostly, what is the difference in the sound. The circuit difference here, and please correct me if this is wrong, is between a Williamson circuit (the one with the triode connection), and an ultra-linear circuit. I would have expected lower distortion with the ultra-linear connection, but maybe not, or maybe there are other tradeoffs. So, can you describe some difference in the sound? thanks.

Conductor, mobile, & arco: This is not easy to resolve; too many variables. I think I see pentode, triode, push-pull, and ultra-linear. I use 2 Heath W5Ms, which use triodes for initial gain, phase inversion, and driver, and then KT66 (beam tetrode) as output, with g2 connected for ultra-linear operation. Two of the 4 Sovtek KT66 output tubes I was using lost their ways and I settled for 4 Chinese "Valve Art" devices. The Valve Art tubes seemed to suffer from excessive Miller capacitance so the W5Ms sounded cutoff at 10KHz or so. Now to the triode pentode stuff: I rewired the Valve Art KT66s with g2 tied to a convenient 400V dc, so that it would perform its original function as a Miller capacitance block. This was successful and upper harmonics have returned. But now I really wonder: If Conductor wires his EL34s in triode mode, will he lose high frequency capability because the EL34s that he has have too much Miller capacitance? Are there EL34s that will be better suited to the triode connection. The CAV50 is wired ultra-linear, I think .. not pentode. Is ultra-linear (which looks very much like triode except that the g2 "feedback" and Miller capacitance is reduced) not a compromise to minimize the odd harmonic distortion of the pentode and also the even harmonic distortion of the triode. Note: mobile, I think your HF-81 is an ultra-linear configuration of the EL84. If that is perfect, what is the difference between it and the Moondogs. Or, are the Moondogs really more perfect. I have heard the EL34 in ultra-linear mode in a revised Eico ST-70 and that was impressive. Is that similar to the CAV50 "sound?" Eventually these questions work back to the speakers. While mobile listens to Cornwalls, I use Forte IIs and RF-7s (both modified), and Conductor listens to something. Of what we are hearing, how much is amp? how much is speaker? And, how much is source or room? Thanks to mobile, Conductor and many others at the Klipsch Forum for informative and enjoyable discussions. By the way, Thanks to everyone also including Gregorius, Colin, and others, for the most entertaining, but much too fast-moving for me, thread: "DecWare Amps."

The "PA Speakers" got me too. I have Forte IIs and RF-7s. With amplification that has little distortion at less than a watt output (very hard for most transistor amps) these speakers are smooth. I found that the transistor amp I used to use was the reasn my Fortes used to sound so harsh. Once I fixed the amp problem, the harshness went away. With both speakers, I've replaced the crossover caps with high-quality polyprop. and the iron core inductors with the air core variety. Also, I've applied dynamat to the horns. As a result, both speakers are less tolerant of amp low level distortion. The RF-7s in particular, gained a lot of presence and articulation with the mods. Stock, I think the RF-7s would tolerate a lower quality signal. But with the mods, they are very revealing. The biggest attraction of the RF-7s for me is that they are 2-way. A crossover at 8KHz can smear a stereo image. I find that 2-way speakers image more easily. I love the sound of both speakers, but the image produced by the RF-7s is much more realistic.

Based on the excellent performance of my RB-5s, reviews on this forum, and a test-drive at my local Tweeter Etc. (av store), I purchased a pair of RF-7s. Brand new, it was clear they were far better than I had expected (for some reason there hadn't been much bass at the store. I used my own amp and cd player too). At home .. bass is the best I've heard in a home speaker. Imaging is also rock-solid. But, I thought they could do more, so I replaced the two (what look like mylar) caps, 5uF and 12uF in the high pass section of the crossover, with a 5uF and 2 parallel 6uF Hovland MusiCaps. Also, I replaced the iron-core 0.75mH inductor in the low pass section with a Solen air core variety. Fnally I applied DynaMat Extreme to the horns. If you can believe it, these R-7s are noticeably cleaner and there is greater dynamic punch. The imaging has depth. With a full symphony orchestra, with horns, cymbals, violins .. everything as noisy and crashy as possible .. the image stays intact and individual instruments continue to sound natural. These speakers provide a true opening into the concert hall. Chamber music is a piece of cake for these things. Oh, don't forget to remove the grills. Setup: Speakers about 9' apart within a foot or so of the corners of the room pointed directly at the listener. Listener is about 10' to 12' back. Amp. is a custom based on Tripath TA1101B pwm chip. About 10W max output (can feel the speakers at less than 2.5W). This amp "sounds" mostly like a reasonable Ultra-Linear tube amp (the Eico ST70, with upgraded polyprop. caps sounds similar). CD DAC: Sonic Frontiers TransDAC Phono Pickup: Grado Gold through a Creek OBH-8SE preamp. Cables are all Monster .. the kind that use Litz wire. I can't remember the names. Anyone interested in a speaker for classical music should seriously consider the RF-7s, and I would suggest a nice tube amp (not a $5,000 tube amp, just a nice one). Maybe there are some transistor amps that can handle the fractional wattage at which most listening will take place, but I havn't heard one. Maybe someone on this site who listens to classical music can suggest amp alternatives. Nice going Klipsch. To get anything close to this from a different designer/manufacturer would cost easily $5K and up. I'm thinking of Quads, for instance. And then you need a BIG amplifier and some way to get those real low notes. These RF-7 are a real achievement.

The attachment didn't work: I'll try something simpler: Woofer Cap (110uF total) 100uF metalized polprop. Solen $24.55 10uF metalized polprop. Solen $3.80 Woofer Inductor 2.75mH Air Core Solen $19.50 Mid Cap 1.5uF film/foil polyprop. Hovland $18.30 Tweeter Caps (2 per speaker) 2.0uF film/foil polyprop. Hovland $20.75 This sould come to $107.65 per speaker.

Crossover upgrades: Did you check-out the posts from aabernathy? They're for the Forte. I found values for the Forte II, which, I think is what you want. If you look at the crossover in your speakers, there are 2 2uF caps and a single 1.5uF cap. I replaced those with Hovland MusiCaps. There is a 110uF non-polar electrolytic. I replaced that with a 100uF and 10uF Solen polyprop. in parallel. Finally, there is a 2.75 milliHenry (not micro) iron core inductor, and I replaced that with a 2.75mH air core by Solen. I purchased the parts from Madisound at madisound.com, just as aabernathy suggests. Warning: the MusiCaps are pretty big, the Solen caps are huge and the inductor is bigger than huge (look at the specs at Madisound. The resulting sound is absolutely fantastic. Also, be sure to apply Moretite or DynaMat Extreme to the horns. These mods will double your enjoyment of these speakers. I will try to include a text version of the Madisound order as an attachment:

You really should try the Reference series speakers, especially the RF7. RF5 is nice too. In order to get highs as clean on my ForteIIs I had to replace crossover caps & iron core inductor. Now the ForteIIs are real nice, but still may not be quite as clean at the very top end. I listen, mostly, to classical. Amp: 2 Heath W5Ms, rebuilt .. new caps -or- Custom 6W/ch based on Tripath TA110B

I have "biamped" my Forte II speakers. It wasn't true biamp in that I fed full range signals into the woofer low pass section of the crossover, which I had completely separated from the crossover assembly, and the upper bandpass/highpass pair, and let the speaker crossover sections reject unwanted frequencies (total 2 stereo amplifiers). I placed one stereo amp on each speaker so that there would be no crosstalk between the channels (my main objective). I like the arrangment because I find the imaging improves without right-left crosstalk. As to power .. well, I saw some improvement (my amp is 10 watts max) but nothing real big .. maybe 3 dB. What was interesting was that as a rule, bass was not the real power user. Midrange was. rim shots on a single snare drum make real big power spikes on the high freq amp. I've never had the amps clip. The speakers get very very loud. he most I can take is about 4 watts (that was the snare spikes) and I was worried about my ears. If you do this. You might consider adding a resistor, maybe 50 to 100 Ohms in parallel with each of the 4 amps, to absorb some of the unused frequencies. Otherwise they might just bounce around and find some nonlinear path into the frequencies you want to hear (no kidding). Good luck.

I have been working for several years, with substantial success, on what may be a related problem. I believe the root cause is, simply, distortion. Consider audio material in the frequency domain rather han the time domain (your ears are frequency sensors, not waveshape sensors). Audio material consists of collections of discrete frequencies. Distortion is non-linear and creates sum and difference frequencies based on all of those original frequencies. I suspect that the mere existence of distortion-sourced frequencies is enough for your "ear" to sense that the source is something other than the original instrument. This is why even the slightest distortion (0.1%) can be so harmful. On to imaging: Center channel sound will contain equivalent material in the right and left channels. Distortion is likely to produce somewhat similar additions in both channels, so it will remain centrally located, along with its distortion. But, now add different material in the right and left channels. The right channel distortion components are different from the left channel distortion components so what seem to be center channel events are now slewed all over the sound stage because they are sourced by sums and differences of frequencies from different locations. (Consider a 500Hz center-channel vocal fundamental that is is combining with 800Hz right-channel piano fundamental resulting in 300Hz and 1300Hz distortion products in the right (but not the left) channel. Does your ear try to correlate te newcomers with the piano or the voice?) Now consider the very complex problem of re-creating a concert hall and orchestra. A flute, 8 feet back and 4 feet left of front & center sounds ok by itself. Now add the rest of the orchestra and all of the echoes that we are supposed to use to re-create the image of the concert hall, plus sums and differences of all of the harmonics. In the end, one begins to wonder why stereo works at all. My point is, even the smallest amount of distortion can mess up imaging. But, there are solutions. Klipsch speakers give you very low distortion for your stereo dollar. Most transistor amplifiers produce substantial distortion at the low powers where Klipsch speakers operate. There are amplifiers that are low in distortion at low power and they will improve the situation. They are worth a try. You only need 5 to ten watts of clean power. If you get a chance, try a tube or transistor class A. If you use CDs, get a good DAC. If you play records, get a good, probably class A, phono preamp. Install RF filters at all amplifier I/O (and at the phono preamp input if you use one). Remove all but the highest quality operational amplifiers from the audio chain. If you've done all of this you can now detect differences in interconnect and speaker wires. Monster makes decent cables for reasonable prices (consider the ones that use many strands of individually insulated conductor (Litz wire)). Beyond that things start to get pretty expensive.

Hello Mace, <0.03% total harmonic distortion at 250mW sure sounds fine to me, I don't think my 3130 was anything like that. Let us know how you like the LF30s.

Hello Mace, I'm sure you'll find the KLF-30s to be great speakers. What you may find is that they are greater than you expected .. in the end this is very good. Mostly, I'm refering to your amplifier. I used an NAD 3130 for years and always found the sound from my Forte-IIs to be harsh, with poor imaging. About three years ago I discovered that the primary problem was my amplifier (I discovered this by trying a Nelson Pass 30 watt class A amplifier). Besides what was most likely a very bad case of crossover distortion, my NAD amp used a not so good operational amplifier in the preamp circuit. If you find that you are happy with the KLF-30s and your NAD, then that's it. But if you are disappointed, and the sound seems thin, or harsh, try a good amp, one that performs well at low power (less than 1 watt). Check out some of the amplifier discussions elsewhere in this site The rewarding thing for me about Klipsch speakers is that they are so perfect. The better wou treat them, the better they sound.

Hello amplifier enthusiasts, I find these discussions to be most interesting. My experience with Forte IIs and RB5s and a variety of amplifiers (SS (assorted NAD, Nelson Pass, JOB), Tube (Heath W-5M), ss pwm (Tripath TA1101B based homebuilt)) to resolved down to two areas of performance: 1) distortion at less than 1 watt: Generally push-pull SS amps do very poorly here. Their distortion is specified at "rated output" for good reason. Klipsch speakers are efficient and have transistor amplifiers operating where their distortion is greatest. The Nelson Pass class A is good, but expensive and noisy. The JOB seems to be an exception, but I don't know how it works and it's not cheap. The KT66 based Heath is at its best at a watt or less. The Tripath-based amp is very good, but you have to build your own (see TA1101B specifications at tripath.com). If specifications or measured characteristics are to be used for comparison for use with Klipsch speakers, the power at which the measurements were taken should be included. For me, anything above a watt looses meaning because I listen to my Forte IIs at 1/8 watt (90dB). 2) RF interference. RF seems to trash anything. I've resorted to industrial strength beads on all I/O and power. I use them on the Heath and the Tripath-based amp. Note: there is a radio transmission tower located across the street from my house. This may explain my sensitivity to RF issues. My main point here is that I believe people should be concentrating on amplifier performance at a watt or less. Amplifiers that excell at low power are likely to be amplifiers that Klipsch owners will find most satisfying.

I have been advised to be careful using the term BiAmp. Since you ask the question at all I assume you want to preserve the crossover functionality (low pass for the woofer and band/high-pass for the two horns). I guess that also means you don't intend to perform crossover before the power amplifiers. If all that is the case: Remove the crossover unit from your speaker (mine is a Forte II) and you will notice that the woofer low-pass inductor-capacitor network is connected in parallel with the band/high-pass network. With two foil cuts you can completely isolate the low pass circuit. In the end, in my case, I completely removed the low pass circuit from the crossover pc-board, and moved it (inductor and capacitor) to the far side of the cabinet. I did this because the high frequencies I was feeding to the low pass network, since I don't perform crossover before the power amp, were magnetically coupling to the high frequency section. Be careful. Make sure you completely understand what you are doing before you start making changes. I like the results. I think the imaging is improved with either twin amps per side or simple bi-wiring.

Two general questions about modifications to the Forte II: 1) Is the K-79-K tweeter an improvement over the K-75-K? If so, can I take advantage of the improvement by adapting either the entire tweeter assy., or just the horn portion, to my Forte II speakers? 2) What are "Bucking Magnets" for?