Klipsch type '4' crossover

[LARRY]

I need to find information on a type '4' crossover. I purchased a very old pair of Hersey speakers (no markings, but size is correct) with type 4 crossovers, K55v and K77 horns and Electrovoice woofers with Klipsch decals. The crossovers are similar to tye Type 4RB, but have two inductors and the layout is a little different. Any help would be appreciated.

Larry

[JohnA]

Can you sketch it and post a scan? What detail are you looking for?

[LARRY]

John,

I will remove the crossover and take a picture and post. I am trying to verify the crossover points, in that it has two large inductors with one of the inductor leads going to the positive side of the squaker. Capacitors are 1 and 2 ohm. I will try to take the picture asap.

Larry

[Groomlakearea51]

IIR the type 4 became the type E at some point; check with BEC to see if he has a schematic.

[LARRY]

I was unable to take a picture that would show the details of the crossover. I will try for a better picture at a later time. However, I drew the following sketch. The green lines are the Inductors, the red lines are the capacitors and the brown line is from the 2.5 MH inductor to the 1.0 MFD capacitor. As you can see, I have no artistic ability! It does not appear to be a Type E.

Larry

[Malcolm]

Schematic is just fine...

Your Type 4 Network was followed by the Type C in the early H700s. Don't know if there was anything in between. Same capacitor values, same 2.5 mH inductor in the woofer circuit, but the other inductor deleted, same 1 uF cap on the input to the autotransformer. Don't know if the taps on the autotransformer are the same. You'll need to check against a Type C schematic. The Type C was followed by the Type D in which both caps were 2 uF and different taps were used. That was followed by the Type E which did nothing more than change the phase of the drivers relative to each other.

[LARRY]

Malcolm,

Thanks for the reply. The autotransformer has the same tap layout as the T2A, so I would assume it is a T2A. The extra inductor is approximately the value on a 5000 Hz limit to the midrange horn. The horns in the cabinets are K1000's (1000 Hz). It would appear they are not original as the crossover refers to a 700 Hz crossover of the midrange. I am going to assume that it is a early Type E with an extra inductor to limit the midrange.. all negative terminals are tied together with a ground wire. I will try reversing the ground to positive on the mid and HF terminals to correct to 'like a Type E2.

Thanks, Larry

[Malcolm]

The taps on the Type C are different from the Type D and Type E. I would bet your Type 4 matches the Type C taps.

You might want to consider when playing with the crossover that the Type 4 and Type C were used with 16 ohm woofers and the Type D and later were used with 8 ohm woofers.

The E2 was on the way to the Heresy II and had modifications to deal with the change from the K55V to the K53K squawker.

My guess is that your K1000 horns are original. If they aren't there should be obvious evidence of a patch to the motor board because the K1000 mouth is narrower than the K700.

Have fun.

[LarryC]

The horns in the cabinets are K1000's (1000 Hz). It would appear they are not original as the crossover refers to a 700 Hz crossover of the midrange.

Hm, I wonder if it isn't possible -- K-1000 mid horns were used on Shorthorns, and the Heresy was introduced before Shorty was discontinued.

[Malcolm]

Early Heresys did have K1000 horns.

[LARRY]

Mystery solved! Thanks to all of you for the input. The Klipsch E/V woofer is 16 Ohms (11,2 ohm on meter) and compared to the Type C (just happen to have two of them), the taps are the same 5,2,1 and 0 for the negative input. The Type 4 is the same as a Type C, but with an inductor to limit the midrange, The K55V's are the push button type and I guess the inductor was to 'tame' the 9000 Hz peak.

Thanks, Larry

[JohnA]

Your crossover is most like a Type C. I don't have a schematic here, but the Type C uses the taps on the Type E I modified as an experiment. The difference is the addition of an inductor to give the squawker a band-pass filter. If you move the squawker tap to #1 without the resistor, the 2uF cap should be 1 uF.

Don't read too much into the calculated -3 db points of the crossover. Sometimes you have the use the "wrong" value to shape the acoustic response so that the acoustic crossover point is smooth and where you really want it. That is in fact why a 2uF cap is in the tweeter filter. It trims a bump in the response of the K-77 from about 5k to 9k.