Klipschguy

I am considering a vintage (late 70s through maybe 2010ish) solid state amp to use in a second system. Do you all have any favorites that sound good, are quiet (very important), and durable. High power rating is not necessary (especially at 104dB/1M 1W). No tube amps, please (I like tubes, but not this go around).

Thank you Grindstone! That is very thoughtful.

No one has called me a kid for decades; why do you think I didn’t know how to use them!

Thank you for catching my oversight; it has been corrected.

I would like a copy of “Dope from Hope.” I am more than happy to pay for it. Does anyone have any information about acquiring these writings of Paul Klipsch?

Yes, of course; thanks Mustang! 😉

.…especially when he realized just about every Klipschorn and La Scala from the 1970s left the factory with a ferrous inductor screw! 😇 (I figured out emojis, my first.)

Paul Klipsch could fix it with a steel screw. (I would add a winking emoji, but I have no clue how - never added one.)

Here is a response curve for the Khorn. Interestingly, from this graph it appears a little boost between 5000Hz and 6000Hz would indeed be beneficial to the high frequency balance of the loudspeaker.

Thank you for taking time to respond, Babadono. That looks a good plan for additional tweeter protection. Andy

Edgar those are events we never want to see. I assume the equipment was plugged into the surviving surge protector, which sadly only protected itself.

Just a little levity rooted in the movie “Back to the Future.” -Thank you for your indulgence. On a serious note, I am interested in tweeter protection, but not replacing the tweeter. Any advice is certainly appreciated and given respectful consideration.

Yes, which did protect my tweeters from the 1.21 gigawatts they received during a scientific experiment.

K77, yes with AA network

Empirically speaking, it seems like DC will fry a voice coil MUCH quicker than AC, but as a student of science and engineering (many years ago) what you are saying rings true.

Thank you for the replys. If 25 watts into 8 ohms gives about 14 volts and 1.8 amps, I assume varying output of the alternating current would probably still not blow a 1A fuse?

One of the forum members recommended a fuse to protect the tweeters against an unexpected surge, such as accidentally unplugging an input cord with the volume up. Klipsch recommends a 1 amp fast blow fuse. Does anyone know what the recommended voltage rating would be? I found a fuse holder that looks like it should work well.

Yes, Henry. Thank you for the solid recommendation. Here is a screw terminal fuse holder that looks interesting. Andy

Not the 2.4mH inductor in the woofer leg, but rather the .245mH in the tweeter leg of the AA network (notice the decimal). The Type A network does not have an inductor in the tweeter leg because it is a simpler design with less roll off per octave. The .245 inductor is the round thing in the top right corner of the picture BESIDE the 2.4mH inductor. Note the shiny ferrous screw in the middle; that little guy is what changes the inductance depending on whether is a material that is attracted by a magnet (like good ole steel), or not (like brass or stainless steel).

I think Bob intended his crossover to be used with a different tweeter. A 6dB slope at 4500Hz with a K77 is probably pushing the limit. Although, as stated earlier, my brother’s Khorn do just fine at 6dB/oct at 5000hz. The 2.4mH inductor won’t change the tweeter crossover point but it does cause a 90 degree phase shift in the woofer leg of the circuit.

I understand. I would think a Type A should do just fine at 110dB peaks, if the power is clean and the treble control is set to flat. As you know, 110dB is VERY loud. I know my brother pushes his Khorns pretty hard at times (6dB/oct at 5000Hz), but always clean. As always, thank you for your thoughts and taking the time to reply.

Dean, I thought you liked the Type A? It would have a lot more IM distortion vs a 18dB/octave at 4800Hz. I think the more favorable frequency response would far outweigh the slight increase in IM distortion. BTW, thank you for your response.

Hi TigerWoodKhorns, I do know that Paul Klipsch liked shallower slope crossovers for sound quality. I think he went to steeper slopes mostly to protect tweeters. At 18dB/octave coupled with the zener diodes, I think the K77 would be quite safe at any reasonable sound pressure levels in home use. My brother’s vintage Khorns use a K77 with a 500–5000 crossover, which has the crossover set at 5000Hz 6dB/octave for the tweeter. No zener diodes. He cranks them up all the time and there has NEVER been a problem (200wpc available, but not used). He does keep it reasonable though (sub-ridiculous). The Type A is 6dB/octave at 6000 was used for years and is a very reasonable crossover for home use; it provides WAAAY less protection than the AA with the ferrous screw. At a 4800Hz crossover frequency at 18dB/octave, the K77 would be 18dB down at 2400Hz, 36db down at 1200Hz, & 54dB down at 600Hz. At a 6000Hz crossover frequency at 6dB/octave (Type A) would only be 6dB down at 3000Hz, 12dB down at 1500Hz, & 18dB down at 750Hz. The K77 may have a little trouble reaching below 5000Hz, but then again, the K55 has some issues reaching 6000Hz, so a little lower crossover point for the K77 is probably a good thing.

K77-M. What reasons? It seemed OK from the factory with the ferrous screw.

Yes. Pushing the crossover point down by raising the inductor value, or by just keeping where the factory originally had it in many cases, is easily audible (and for the better, in my opinion). As for others seeing the value….well…