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It's in the Tripath specs for the TA-1101B. Absolute max is 16V, but don't to it!. Max operating is 13.2V. I would try to keep the supply between 11.5V and 12.5. Leo

I recommend using a larger DC supply. The one I used with my P6D was 12V 3A and from some reports of clipping it could have used maybe 4 or 5 Amps capability. If you use a smaller supply the amp will run out of current and clip at lower amplitudes than necessary. It is very important not to exceed 12V as this will fry the Tripath chip. Leo PS .. I just reviewed the math. 3A should be about right (1.5A per side). The power conversion is about 90% at high output which, after accounting for close to a Volt of switching loss at each rail produces .9 x 10 x 1.5 or 13.5 Watts driving just under 4 Ohms. Power will be lower before clipping at higher impedances.

The RB-75 and 81 look close .. I don't know how they compare. I currently drive a pair of RB-5s with an older, slightly less powerful Tripath chip (see below). The rB75 or 81 would be louder due to better efficiency and the TA-2020 (assuming you're using the recommended power Voltage) is more powerful. So, I would expect very good sound and ability to play loud, but not painfully loud. Leo

Rick, I think the Paramours use an "ultrapath" output configuration. The ultrapath approach uses an inductor to supply the DC bias current to the output tube and a small, audio only transformer to match output impedance for the audio signals. This way the audio output transformer can be optimized for audio. A more traditional approach its to combine the bias and audio functions into one, rather large output transformer which is hard to optimize for high frequencies because of its magnetic "size" and is intentionally limited in low frequency capability to prevent magnetic saturation from the DC bias current. I believe this is why SETs have a limited audio extension reputation. I've found the parafeed approach to significantly extend both high and low end of a SET design. However, I have had some trouble with resonances, but have most of that taken care of. Long story, but that's as short as I can make it. Anyway, after all that work fitting my Moondogs with parafeed out I wondered if it may have been a better move for me, in the first place, to purchase a parafeed designed amp like the Bottlehead designs. Most likely they wouldn't have had the resonances I had to purge from my mods. With your Paramours, have you tried the 4 Ohm speaker taps? That may tighten the bass and provide an overall smoother response (not a trick, just better impedance matching with the speaker's low impedance dips). I suspect the Bottlehead constant current source is for a gain or driver stage, not output .. but I'll look it up. Parafeed generally uses a big inductor to supply the output current. One of these days I'll get to hear one of the Bottlehead amps. Leo

Rick, Just as a point of reference, I changed the output config of my Moondogs to what is now parafeed. Your Paramour 2A3 is already there. I think, in comparison, you might find the standard config which uses one big output transformer for both current source (bias) and audio to be a bit constrained at both frequency extremes. Have you compared? If so I'm curious about your opinion. Leo

Well implemented SET has a very natural sound. Mine are pretty much standard with the RF-7s. I try other amps and then end up going back to the SETs. Glad you've had an opportunity to hear the technology done well. Leo

The simple answer is 1) there is a radio station near your home and 2) various nonlinearities in your audio system (probably the phono preamp) are demodulating the RF. Try RF filters in 1) your power lines 2) the phono leads ("RF Ferrite Beads") 3) speaker leads ("RF Ferrite Beads") 4) other line interconnects ("RF Ferrite Beads") All of the leads I mention can act as antennae (I think that's the plural of antenna) which pick up the signal that eventually finds its way to the demodulating circuit. When you approach the phono pickup you may be enhancing the antenna affect of the phono leads or supplying rf ground which enhances the rf signal picked up in one or more of the other leads. Good luck. I have a radio station across the street. It's in everything. Leo

Hello HPower, I ran into that thread right after my initial response on this one. So much for trying to buy local. Your comment on the subject, including the availability of quality Chinese products are well taken. I would be interested in how Audio Space does phase splitting, because the rest of the approach can result in a very nice amp. I'll watch here to see what turns up. Leo

I can comment on the configuration. Class A pp can preserve many of the natural or neutral sound benefits of well implemented SET while adding benefits of higher power and lower output impedance. It would be helpful to know the phase splitter design. I prefer a "differential pair" over the cheaper "concertina" design .. the latter adding a significant coloration to the sound. Another thing that is beginning to impact my purchasing decisions is, in the interest of helping out my neighbors, to consider paying a few more dollars for American made. There are many excellent US and certainly Canadian designers and builders who deserve consideration, and the additional cost. (In the loudspeaker department, Klipsch is a good example) Leo

Digital info has been tacked on to FM stations for years. The "HD" version is a recent commercialization of a particular proprietary scheme by which an FM station can add two fair sounding (and I mean that in a positive sense) digital substations to its analog carrier. So the station is 3 stations: the stereo analog original and two additional stereo digitals for which listeners must purchase a receiver with HD capability. There are a few amusing questions raised: like if the original station really made good use of its channel's analog bandwidth and dynamic range would there really be room for two additional ok-bandwidth digital stereo channels? And: was anyone really taking advantage of full analog bandwidth and dynamic range of any station that offered it? But that's history and HD can be very good radio .. in a similar way that web radio can be good radio. It isn't CD, but some of the encodings are quite impressive. Leo

I have the Sangean HDT-1 and have found it a capable tuner. I have stopped using it because I have a multipath problem where I live and can't find an FM antenna with a reflector bar. I will either find one, or build one. Anyway, the tuner does require a fairly clean and strong signal or the dropouts get annoying real fast. Sound is pretty much a function of a particular station's care in digital encoding. Some stations were impressive. If you meet the signal requirements for stations in which you are interested, the tuner is worth obtaining. By the way, I find that various web radio feeds have sonic capabilities (and source-specific variations) similar to what I found with the Sangean. With my web radio I do use my own external DAC which makes a big difference. The Sangean DAC was OK (my web radio DAC really isn't OK). I don't know if there is a digital out on the Sangean or if you'd want to use it. Leo

If you really have the Cornwalls stacked I wonder if the upper pair are really able to produce effective lower bass. 1st problem is floor reflection from the upper woofer which, due to the added distance (woofer-floor-ears vs woofer-ears) causes cancellation at certain frequencies. It's often best to keep woofers as close to the floor as possible (as reflected in the Cornwall design). 2nd problem is related: Cornwall woofer-port combination may depend on the close proximity of the floor for effective low frequency delivery. Cornwall owners may want to comment on that. Try using only the lower pair. The total acoustic power capability may be reduced so it's not quite the same physical experience, but the lower bass may be in better balance. There are plenty of reasons a 10" sub may go lower than a 15" woofer, but that may not be what you're hearing. Check the specs on the Cornwall. In a floor-mounted situation, that's how low it goes. Your sub probably goes a bit lower. Leo

The only advantage I can think of is flexibility for a range of power requirement situations, with low distortion not being the highest priority. Leo

Gee, if the 2 smaller amps bridged are supposed to be better, one of them alone might be really great. Over 100W into the RF-7 is pretty serious (I'm using two 3.5W mono amps into my RF-7s right now, but as I always say, I don't listen real loud). I'd compare the two amps (RB 1080 vs RB 1070) without bridging the smaller one. I suspect you're a bit tied up with the Watts and should be listening to the sound. Leo

Regardless of how much power you think you need or want, the distortion level of the amp at low power (1 Watt and lower) has a lot to do with how natural and un-grainy an efficient speaker like the RF-7 will sound. It could be the dealer is suggesting the amp with lower low power distortion. Can you compare vocals on both? One may exaggerate sibalances ("s" sound) more than the other, possibly to the point of being a problem. Leo

Note that Duke, who is a better Crown reference than I am, writes "D-75/2." The original D-75 may be a bit harsh. The version two is the one claimed to be as compatible with high efficiency horns as the D-45. Leo

ka7niq, That's a lot of very good information. Thanks. Also, congratulations on securing a pair of the right vintage for yourself. I'm sure you'll enjoy them. Leo

Or put differently, Is a 6" port the way to identify both CF-3 and CF-4 1st editions? I've decided if I ever saw either speaker for sale near Boston I would jump at the opportunity and figure out later if the RF-7 or Chorus-II would have to go. Also, can both version 2s be easily reworked to 1s? Leo

Thebes, Nice tape deck. I had an Akai X200-D .. somewhat similar. I think you have the tape threaded correctly for record/playback. I don't think the tape should go over the top of the roller on the left side as suggested above. The extra spindal just above and to the right of the heads is for winding/re-winding without going through the heads. The tension arm on the right has to be included in any wind-rewind operation or the motor(s) won't go. It also provides auto cutoff for the wind operations. Enjoy! Leo

Oh, I meant to write: D75 series 2 (not D70). Thanks, Duke, for the correction. I'm less likely to screw up the "D-45" because I can read it off the amp front panel from where I sit at the computer listening to the "La Stravaganza" SACD by Rachel Podger and Arte Dei Suonatori. The Crown and Chorus-II bring this recording sooooo close to the live sound. Leo

Crown D-45 with stereo passive preamp (attenuator / volume control) and source selector if needed. The Crown is a pro. amp and has balanced or 1/4" phone jack input. If you're interested, research the equipment and understand how it all connects and works. I find the Crown to be a perfect match with Chorus-II. Some here say the Crown D-70 sounds as good. I don't know. Leo

I played the two wave files: absolutely no distortion. Very powerful "s" but totally clean. Leo

I removed the shunt resistor and there is a bit more energy in the upper midrange. There is no added distortion. Sibilances are a bit stronger, but not distorted. So, at this point the only crossover change is the capacitors. Generally I like the sound. Well recorded material is quite impressive. The added energy seems to work well, as I guess it should since it is the original design. If I can get those wav files to a disk I may be able to give them a try. Leo

I am certain the problem you are having with sibilance is not the "peak" I refered to, and at this point I am curious as to whether or not I would hear a peak if I removed the resistor in my RF-7s. I suspect I was addressing a distortion problem by messing with the frequency response. Since then I have made several much more important changes in reducing distortion. So, over the next few days I will remove the resistor and report back. Leo

The circuit involved is a bandpass shunt across the horn to flatten its response at frequencies where it peaks in efficiency. Lowering that resistance was one of the first things I did to tame what I thought was a peak in the horn's output (the resistance reduction I used is a bit less than Dean's). The speaker is so smooth now I should try removing that shunt. On the other hand, the speaker is so smooth now, maybe I should leave it alone. Leo