Klipschguy

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I have a tone generator app on my iPhone that will produce audio spectrum frequencies; it is useful for identifying room resonances, bad speakers drivers, et cetera. I use a free app called Sonic. A word of caution: Be careful with cranking the individual frequencies of the audio spectrum as it can damage your system. Ex: cranking 20,000Hz trying to hear it can fry your tweeter (“It was only 146dB, but I can hear it!!), or cranking 20Hz trying crack the foundation of your house can damage the woofer. Moderate levels and common sense are recommend.

From your description, there is a good chance you have a bad diaphragm either in the tweeter (K77) or the midrange driver (K55V). Play the distorted passage with your ear beside the midrange and alternately, the tweeter to determine the offending driver. (Piano music is usually good for revealing a bad midrange horn diaphragm.) The original drivers can be repaired.

Thanks, Jim. Those attenuators look like they would work well.

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Peter speaks the truth.

Yes. My apologies for not being more clear. (Funny, the “Old School” in me tends to assume everyone is running their Heritage with a more traditional 2 channel preamp/amp combination.)

Thank you, Babadono! That is exactly what I need.

Yes. The sub will crank right up without the mains. There just does not seem to be enough voltage to drive the sub because the KHorns are so sensitive/efficient. What is the best way to add gain to the sub?

I would recommend taking the other screw to a local hardware store, confirm the thread (you can try various hex nuts until you find the one that fits), measure the length of the threads to get your machine screw length, and then buy the screw from that store if they have it, or look online to find the exact screw you need.

Well my subwoofer’s plate amplifier has an internal crossover (actually, a pretty good one), so there is really no need to tap into the woofer leg of the Khorn’s network because the sub only allows the low frequencies to pass to the driver any way. Also, a Khorn’s woofer leg crosses over at 400Hz (around the middle of the piano), so the frequency range would not be appropriate for a subwoofer which should really operate at frequencies about 80Hz and below. However, you do give me an idea for a potential solution: I could make a resistor box that brings down the amplifier’s speaker output to any potential “line level” desired. Thank you for your thoughtful replies. Respectfully, Andy

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Ok. Thank you for the replies. I can probably adjust the input sensitivity/gain by soldering in some different resistors. Now to find a wiring diagram…

The sub is running off a level input from the preamp, 2 channel setup. The volume is maxed on the sub, hence the need for more gain.

I have an M&K sub with a Khorn setup. The Khorns are so sensitive, the sub does not have enough gain to properly match the line level for an appropriate mains-to-sub balance. There are some subs with adjustable input sensitivity; this sub is not one of them. Any recommendation or experience with changing the input sensitivity (besides “Buy a new sub.”? Maybe solder in some different resistors so volume control will have enough gain?

Thank you, Mike. I also find the information quite interesting. Cheers to PWK (and you as well).

The Type A network has the tweeter leg at “tap 5” but after the 13uf capacitor. I would assume the T2a would still provide some degree of the protection even though it seems the K77 is being run “wide open”?

Interesting. The slope is indeed constant, albeit there is about 3 more dB roll off for the tweeter relative to the squawker at 1KHz (20dB vs 17dB). Thank you for your insight and taking time to run these curves.

Brilliant! Thanks for posted the plot, Mike. If you don’t mind me asking, what if one took the E Network from “tap 3” to say “tap 2” in the tweeter leg, how would it impact the roll off?

OK, it is my understanding from reading a recent post that the inductance of the T2a (+ a capacitor) protects the squawker by giving an effective slope of about 10-12dB/octave. What effect does it have on the tweeter leg of the circuit (like the E Network)? PWKs use of the autoformer in his networks was brilliant.

True, but the effect on the midrange will typically be more audible than a few Hz at the bottom end.

Hi Peter, With 50 year old speakers, who knows if the damping is original or not. If it the factory damping, then they probably figured it out and I would recommend leaving it alone. The amount of damping material affects not only the bass frequencies but also how much midrange in the box that is reflected back to the woofer and then into the room; some of the midrange reflection back into the woofer may or may not be desirable. Best, Andy

Tragusa3, Thank you for sharing your experience - it helps. As an aside: In a social gathering situation (or if I am moving about) I like to run my system in mono so everyone basically hears the same thing around the room. Sadly, many preamps no longer have a mono button.

Dave, I assume flying would suspending the speakers with cables? I hate to drill any holes in the cabinets. Can they be flown without drilling?

Interesting. I guess opposing speakers would image like a pair of headphones, if one was in the right spot.