jdm56 Posted January 25, 2001 Share Posted January 25, 2001 Al, (can I call you Al?) I like your 2 into 3 box. What would be the relative advantages/disadvantages of trying to accomplish the same thing, but at speaker level? I currently am running an integrated amp w/o pre out / main in jacks, so that's pretty much my only option. Thanks, Blind Melon McCall (but you can call me Betty) Quote Link to comment Share on other sites More sharing options...
Al Klappenberger Posted January 25, 2001 Share Posted January 25, 2001 I have not tried it, but you may be able to use just two resistors to bridge a third speaker at the power amp output. Don't use the third resistor to ground though. The question becomes what value and I really don't know. Start with about 10 Ohms each. The value will set the loudness of the middle speaker. Too low and you might casue instability in your amp. If they are too high , you won't be able to hear the middle speaker. Al K. Quote Link to comment Share on other sites More sharing options...
G Evans Posted January 25, 2001 Share Posted January 25, 2001 All HH Scott tube amps ( like the 222, 299B, 380 etc) provided a derived center channel using the amp 16 ohm outputs via ( I'll check) 10K or 22K resitors. If the center channel amp is a sole power amp without a volume control the center resistor could be a pot to tweek the level as .. Watch the center channel level wrt flanks as it can shrink the sound stage if too high. ( -8dB , as Al. K says :-) I even found that effect with a sub ( even though it rolled off at 30Hz) which is why I use the sub to one side of the room not between the flanking La Scalas. The minus side to using a Heresy or Cornwall as center speaker is that you loose the all horn clean bass which is why the Belle was designed. George Quote Link to comment Share on other sites More sharing options...
Al Klappenberger Posted January 25, 2001 Share Posted January 25, 2001 Mdeneen, Using power resitors at high level is definitely NOT the best way to do a 3 way system, but I wouldn't worry about the inductance of the resistors. That amount of inductance is far less than already in the drivers themselves. Anyhow, you can by noninductive power resistors if you are worried about it. I use them in my networks. You will loose damping in the middle speaker since it will be isolated from the amp. This is not the case for the flanking speakers though. Damping will not be degraded on those. As to impedance, it will lower the load, but I wouldn't worry about that either. It's insignificant compared to the 0.2 Ohms or so source impedance of a typical amp and the normal variation in load provided by the speaker itself. They are by no means a steady 8 Ohms! The big disadvantage if using resistors at the amp outputs is the loss of damping in the middle speaker and the difficulty of setting the levels, which is very important. The chance of instability is also real. A third amp is really the way to go! Al K. Quote Link to comment Share on other sites More sharing options...
jdm56 Posted January 25, 2001 Share Posted January 25, 2001 Thank you, Oh mighty wizards! As I am elctronically challenged, the ideas expressed are very helpfull. Not long ago, I was seeing "passive home theater" boxes being sold at close-out prices at many of the electronics mail order outfits. (Dynaco and Chase Tech. were the brand names) I think the Dynaco derived 5 channels from a 2 channel input at speaker level. I almost ordered one for $20.00, but figured it would soon be rendered unnecessary by SACD and/or DVD-Audio. This was probably two years ago. It seems the Chase box worked at line level, requiring a separate amp for the center output. My question is; does anybody have any experience with these things? Know where they may still be available? Inquiring minds want to know. ------------------ JDMcCall Quote Link to comment Share on other sites More sharing options...
MacKlipsch Posted February 1, 2001 Share Posted February 1, 2001 I have had Klipschorns and a Belle center channel for 15 years....I love it....I have an 18 foot wall, so the difference is noticeable....I will try to post the "Dope from Hope" that deals with this subject. I will upload in 2 attachments...If it doesn't work, feel free to e-mail me and I'll send them to you.... Quote Link to comment Share on other sites More sharing options...
G Evans Posted February 2, 2001 Share Posted February 2, 2001 MacKlipsch The Dope from Hope drawings do show the best way of doing things IF you have a low imp. out preamp which guards againt L/R crosstalk. Most people these days prefer to go from source to power amp directly via a volume pot driven from a very low z out source like CD (I do) or RIAA preamp with a good line driver (cathode follower ~ 600 ohm). With the resistor values given 27K + 25K pot the cross talk expected (as a function of preamp zout): Zout Xtalk (dB) 600 ohm -43dB 1K -38dB 4K -27dB 10K -20dB ** 50K -11dB 100K -9dB Using lower value resistors in the combiner will worsen these ofcourse .. Many PU cartridges have xtalk figures of around 20dB, so some of you will rightly argue that even highish ** output z's are of no consequence... your choice :-) but would 'degrade' the superlative spec figures achievable with a typical CD player.. BTW, I have a collection of Dope From Hope up to 1978. Untill when were they publisehed by klipsch ? George Quote Link to comment Share on other sites More sharing options...
TheEvan Posted February 2, 2001 Share Posted February 2, 2001 After reading some of this i went to my storage building and dusted off a languishing 60's Fisher KX-202 integrated amp. Actually, my intent was to try and localize the problem that caused me to put it away so I could bring it in to a tech. Wellll, the fuse holder was loose, THAT's what was wrong. Blush. I confess, I never paid much attention to the hookups & knobs, but lo & behold it has a center speaker output with a widely stepped attenuator...maybe 8 positions. So I'm going to experiment with an old Sansui speaker before I start looking for a Belle, LaScala, Heresy, Cornwall, etc. BTW, the Fisher sounds pretty darned good. A bit more forward and punchy than the Jolida 302b I've been using. Bigger in the mid-bass and tighter in the low bass. The phono section sounds pretty good, too. Full-function, tape monitor, etc, doesn't hurt either. It uses 2 7591's per channel and I'm guessing it makes 20 or so watts per channel. Quote Link to comment Share on other sites More sharing options...
TheEvan Posted February 3, 2001 Share Posted February 3, 2001 oops, that's a KX200 Quote Link to comment Share on other sites More sharing options...
Shock-Late Posted February 3, 2001 Share Posted February 3, 2001 quote: Originally posted by MacKlipsch: I have had Klipschorns and a Belle center channel for 15 years....I love it....I have an 18 foot wall, so the difference is noticeable....I will try to post the "Dope from Hope" that deals with this subject. I will upload in 2 attachments...If it doesn't work, feel free to e-mail me and I'll send them to you.... Well with such a huge wall and klipschorns in the corners i can understand what's nice about a center speaker. I believe the dimensions of my listening room, plus the fact i use scalas, are responsable to the fact i don't want a center speaker. Al, sorry i was dumb about the "left-right mix". I didn't know there was the 6 db thing (see a few posts before ).But the idea disturbed me. Regards, Frans Quote Link to comment Share on other sites More sharing options...
MacKlipsch Posted February 3, 2001 Share Posted February 3, 2001 quote: Originally posted by G Evans: MacKlipsch The Dope from Hope drawings do show the best way of doing things IF you have a low imp. out preamp which guards againt L/R crosstalk. Most people these days prefer to go from source to power amp directly via a volume pot driven from a very low z out source like CD (I do) or RIAA preamp with a good line driver (cathode follower ~ 600 ohm). With the resistor values given 27K + 25K pot the cross talk expected (as a function of preamp zout): Zout Xtalk (dB) 600 ohm -43dB 1K -38dB 4K -27dB 10K -20dB ** 50K -11dB 100K -9dB Using lower value resistors in the combiner will worsen these ofcourse .. Many PU cartridges have xtalk figures of around 20dB, so some of you will rightly argue that even highish ** output z's are of no consequence... your choice :-) but would 'degrade' the superlative spec figures achievable with a typical CD player.. BTW, I have a collection of Dope From Hope up to 1978. Untill when were they publisehed by klipsch ? George Can anyone restate this in english??? Be damned if I get this Quote Link to comment Share on other sites More sharing options...
Al Klappenberger Posted February 3, 2001 Share Posted February 3, 2001 Mac, The cross-talk is similar to the blending you are trying to get at the middle speaker, but it happens in the flank speakers instead. The desired blending to the center speaker is the ratio of the resistors left and right to center. If these resistors are not a lot larger than the source resistance (impedance) of the source, there will be a blanding of left into the right and right into the left. Just keep the two resistors high, but not so high as to cause capacity of the cable to the middle amp to start shunting off the highs! I put the 12K to ground at the junction to reduce that effect in my little mixer box. Al K. Quote Link to comment Share on other sites More sharing options...
Al Klappenberger Posted February 3, 2001 Share Posted February 3, 2001 Hi guys, I just did some computer analysis on the mixer values I am using and have discovered an added benefit of the 12K resistor to ground at the junction of the two 33K resistors. With the 33K resistors alone, considering a 500 Ohms source Zo, the cross-talk is about -36 dB. Putting the 12K to ground improves the cross-talk to -44 dB. Al K. Quote Link to comment Share on other sites More sharing options...
MacKlipsch Posted February 3, 2001 Share Posted February 3, 2001 Al, You the man...thanks for the translation Quote Link to comment Share on other sites More sharing options...
TheEvan Posted February 7, 2001 Share Posted February 7, 2001 Hey folks, I've decided to unload my Fisher KX-200 integrated. I'll either put it on audioreview.com or ebay. But if anybody here wants it I'll sell it to a Klipsch owner for much less. It has a center channel output with an 8-step attenuator. Very cool. If anybody's interested, email me...I have pictures & info. I'll hang on for about 3 days, then post it for sale on one of the two aforementioned sites. Quote Link to comment Share on other sites More sharing options...
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