AnalOg Posted May 23, 2003 Share Posted May 23, 2003 Cause I'm afraid it may trigger another project!! Tom Quote Link to comment Share on other sites More sharing options...
JLM Posted May 23, 2003 Share Posted May 23, 2003 Dean: Very nice looking work on the crossover. What's a "A" versus "B" crossover? BTW, I'm not a headbanger, so I don't see how a pair of 102 dB/w/m efficient speakers in my 12 ft x 20 ft x 8 ft room wouldn't reach symphonic concert peaks of 103 dB with a 2 wpc amp. Typically I listen around 80 dB (that would be roughly 0.01 wpc in my room). thanks, jeff Quote Link to comment Share on other sites More sharing options...
Dflip Posted May 23, 2003 Share Posted May 23, 2003 The B network crossover is in Klipsch Cornwalls, while the AA and it's variations are in the Klipschorns, LaScallas and Belles as far as I know. Dean: I would assume that your new networks should improve the sound. The heavier gauge inductor alone will make a big difference (bass), over what was in the original equipment. The better quality caps will also help (mids and high end), probably more so at the lower value cap. At least that is what Al K has told me in the past with the B network. The units look great, enjoy. Don Quote Link to comment Share on other sites More sharing options...
Deang Posted May 23, 2003 Author Share Posted May 23, 2003 Thanks Don. Hi Jeff, welcome to the forum! Not knowing your musical tastes and listening habits in advance -- so I made an educated guess. The RF-7's will deliver unrestricted dynamics with SET amps up to 90db with no problem -- as long as you are within 12 feet of them. At 95db and above, things begin to compress. I didn't know where in your room you would be doing your listening -- so I figured worst case. You need to subtract 3db for every 3 feet you move away from them. I'm not always a headbanger -- and I've found the RF-7's do better overall with 20 watts or more. Of course, I typically listen at 90db or slightly higher. Quote Link to comment Share on other sites More sharing options...
JLM Posted May 25, 2003 Share Posted May 25, 2003 Dean: Most folks don't know that the SE84 based Decware amps actually love low impedance loads, the lower the better. Several owners use Paul Speltz's autotransformers to lower the impedance down to the 2 - 4 ohm range to obtain more bass and improved midrange resolution. (Paul invented the autotransformer to raise impedance to match up better with atmaspheric OTL amps.) I'm wondering how much improvement could be obtained by using the autotransformers ($450/pair) with the RF's. The autotransformers themselves are basically just transformers with multiple taps to offer 1/4, 1/2, 2/3, 2, 3, or 4 times impedance options with rather short leads, so they're a minimumal component addition to the system. And using monoblocks, could replace speaker cables. (The attraction of the RF-7 to me is full frequency response with high efficiency from a 2-way speaker, not the easiest thing to find from a reasonable compact design at a decent price. I know lots of individuals offer homebrews or kits, but many aren't very impressive and they're hard to audition.) BTW, how did you come up with the new crossover design? Quote Link to comment Share on other sites More sharing options...
edster00 Posted May 25, 2003 Share Posted May 25, 2003 Welcome to the forum Jim! Several of the members of the BB have tried the Decware amps in their systems, some with great success and some not quite so great. I had a pair of the Signature Zen Triode Mono Blocks hooked up to my K-horns but I returned them at the end of the 30 day trial period. They were very good sounding amps but just didn't have enough power for me. I listen to mostly classis rock and they started "pooping out" in the low to mid 90 dB range. Just my 2¢, your mileage may vary etc. etc. You might try doing a search of the forum archives, you should find several threads devoted to the Decware amps. Quote Link to comment Share on other sites More sharing options...
Deang Posted May 25, 2003 Author Share Posted May 25, 2003 You are talking about a really cool thing that I've never really understood -- transformers in speaker crossovers! I don't really understand how you can not use cables though, don't you still need something between the amps and crossover? Sure would be nice if Leo would jump back into this thread -- he's the guy you need to talk to. Sounds like you two could converse on the same level. I'm not always much of an original thinker when it comes to this stuff. I beg, borrow, and steal everyone else's ideas! My crossover is still the Klipsch crossver -- just a point-to-point wired version with higher quality parts. Nothing fancy going on here. There are only two parts that deviate from the original -- only slightly, for the purpose of controlling silibance in the horn. Well, there is that huge 14AWG inductor for the bass -- does that count? I'll shoot Leo an email and get him in here. Quote Link to comment Share on other sites More sharing options...
leok Posted May 25, 2003 Share Posted May 25, 2003 Sun, AM Jeff, Dean Welcome to the forum, Jeff. The RF-7 crossover is pretty simple. There's an RC filter for the low pass. The High pass is a little more complex with a dip in the middle to flatten the natural peak of the driver/horn. What Dean and I have done is improve the quality of the components and tweak the dip so the peak is reduced just a tad more than stock. The result is a remarkably neutral sound with exceptional high end detail. Used with amplification that has low distortion at low power, the speakers are refined and powerful. leok Quote Link to comment Share on other sites More sharing options...
Deang Posted May 25, 2003 Author Share Posted May 25, 2003 Leo, Would you care to elaborate a little on what Jeff is inferring to regarding the use of transformers. Is this simply an impedance macthing mechanism that accomplishes pretty much the same thing as your 8 ohm resistor across the output connections on the amp? Quote Link to comment Share on other sites More sharing options...
leok Posted May 25, 2003 Share Posted May 25, 2003 I wouldn't consider the use of a transformer (or autoformer) to have the same impact as a parallel resistor. I would use a transformer (and do in all tube amps), to best match the amp output tube characteristics to the speaker load. If Dekware amps don't have configureable output impedance, then an additional transformer is an option. In the Dekware example there is no power to spare .. as is the case with my 2A3 amp. With a higher power amp, there is power to spare, and I suggest configuring the output stage to expect a 4 Ohm load. Then connect an 8 Ohm (nominal) speaker and an 8 ohm parallel resistor to the amp output. This way, the impedance driving the speaker is lowered, overall damping is improved, and the amp tube stage sees a more resistive, and less varied load. I use this approach with my pp amps and find the results noticeably improved over simple speaker impedance matching without the resistor. leok Quote Link to comment Share on other sites More sharing options...
Deang Posted May 25, 2003 Author Share Posted May 25, 2003 Yes, I'm finally getting around to trying your resistor trick. I'll be doing it next week. Should be interesting. Quote Link to comment Share on other sites More sharing options...
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