Older Klipsch Ohms rating

[clearwaterpro]

I have a set of older 1979?-1982? Klipsch Loudspeakers, type HWO, Heresy, serial number 76T706, wooden cabinet. I need to know what ohm rating each speaker has and the wattage of each. Can anyone help?

Tom Simmons

[lynnm]

Hello Tom - Welcome to the forum!

Heresy II Specs: (Specs for the Heresy are essentially the same)

Nominal Impedance 8 ohms

Power Handling:

100 watts continuous

400 watts peak

Turnabout being fair play - Why do you ask ??

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It is meet to recall that the Great Green Heron rarely flies upside down in the moonlight - (Foo Ling ca.1900)

[clearwaterpro]

Thanks, so much for the answer. My reason for asking is that I am trying to put together a small town street dance with a friend of mine and I want to have enough wattage to do it. These speakers belong to a JVC system that my wife purchased new in 79-80. I will be using a Peavey xr-600f powered mixer (200 watts per channel) and I will be singing into a Shure Beta 58a mic. The Peavey instruction manual says that my total ohms on one channel must never go below 4 ohms, which, if I understand, is what two eight ohm speakers total. The only speakers I have so far are the Klipsch. I had been borrowing someone else's music system up to now, and I am gradually building my own.

[djk]

An XR600 'breadloaf' mixer is 200W at 4R. Pre 1985 Heresy speakers are OK for light duty PA, the Heresy II is for all intents and purposes 4R and only one per channel may be driven. To prevent woofer failure a 50hz high pass filter (sometimes called a low filter or subsonic filter) must be used. The E type Heresy networks that you have should be partially updated to E2 type by adding a 0.245mH inductor in parallel with the output to the tweeter. A 561 or 211 automotive dome light bulb must be added in series with the hot lead to the tweeter or it will burn out about the third time it goes into feedback. Eventually you will want to add a subwoofer if you need to run program material with bass through the system. A friend of mine ran his Heresy for PA like this for ten years before upgrading. It was just vocals and acoustic instruments for a duo, but he could fill the local 1900 seat theater with good sound.

[Malcolm]

Nominal impedance of your Heresys is 8 ohms. Actual impedance varies, higher and lower, depending on frequency. Nominal impedance is just a number chosen by the manufacturer to give some overall indication of the impedance. You would need an impedance graph from Klipsch to know what it is at any particular frequency. But it is not unheard for the actual impedance of a speaker to be as low as half the nominal impedance at some frequencies.

The nominal impedance of the woofer is not printed on it. But one can make an educated guess from the voice coil DC resistance. The DC resistance of a K-22-EF woofer out of a Heresy two years older than yours I just happen to have sitting on my desk measures approx. 7.3 ohms and could be considered to have a nominal impedance of 8 ohms. The K-55-V squawker driver, which is a tweaked Atlas PD5V, has a nominal impedance of 16 ohms. The K-77 tweeter, which is an ElectroVoice T35A, has a nominal impedance of 8 ohms.

So, what does all this mean to you? If your manual is referring to nominal impedance, you can safely parallel two Heresys on one channel. If it is referring to the actual impedance at any frequency, you likely cannot. You would have to wire them in series. And then you might not be able to get full power out of the amplifier.

As far as power handling capability goes. It depends on where in the frequency range the power is. I cannot find T35A (K-77) specs, but as far as I can recall, it is somewhere in the range 15-25 watts. The Atlas PD5V-H, the successor of the PD5V the K-55-V is based on, is rated 40 watts. Don't have a spec for the woofer. But looking at the one on my desk, it might be good for 60 watts at the most.

Personally, I would think twice about using your Heresys for sound reinforcement outside. IMHO you will be running a significant risk of damaging them if you are not careful, and maybe creating some trouble with your wife.

djk,

I am confused. How does adding a 0.245 mH inductor to a Type E network partially update it to a Type E2? The only difference I remember seeing between the two was the addition of a 33 uF cap in the woofer circuit. Same caps, same taps on the T2A.

[djk]

"I am confused. How does adding a 0.245 mH inductor to a Type E network partially update it to a Type E2? The only difference I remember seeing between the two was the addition of a 33 uF cap in the woofer circuit. Same caps, same taps on the T2A."

You're right in that I should not try and assign a model number to the suggested rework of the type E network. The addition of a 0.245mH inductor protects the tweeter from excessive low frequency energy. These are the same values in the tweeter section of the B3 Cornwall network. The EV T35/K77 tweeter is only rated for 5W average power by EV. With the suggested network changes it will handle the required power. I've seen many damaged K22E woofers, all were from excessive cone excursion. Used with the recommended high pass filter they will handle the required power. As used in the Klipsch networks, the K55V driver is for all intents and purposes, indestructable.

[Malcolm]

Now that you mention it, 5 watts for the T35 does sound familiar.

I assume what the light bulb does is present a relatively low resistance, close to its cold resistance, at reasonable tweeter power levels, and present a high resistance as it heats up when the power level becomes excessive.

[djk]

Yeah, cold its like the lightbulb isn't even there. Transient peaks don't heat it up enough to really matter either. But if you get a blast of feedback the bulb lights right up and cuts the power about 80~90%.