Utah Heritage HS1-C

[michaelp]

Does anybody have any experience with vintage Utah Heritage HS1-C speakers? I was given a pair, and one of them has no sound in the mid and tweeter. Seems that the L-pad volume control is burned up.
I would like to get this working in its original condition to see what they sound like.
But I am also wondering if it is worth trying to improve them with a better crossover. The crossover in there is really simple/cheap. Any suggestions?

[fpitas]

If you've never designed crossovers before, you're in for a long ride.

You *might* find replacement drivers on eBay. Then, since I very much doubt you'll find the information online, you'll need to measure their frequency response and impedance over frequency. Finally, you can enter those parameters into a SIM.

[fpitas]

You *might* find replacement drivers on eBay. Then, since I very much doubt you'll find the information online, you'll need to measure their frequency response and impedance over frequency. Finally, you can enter those parameters into a SIM.

[michaelp]

Yes, sounds like I might not have the skills and tools right now to design my own crossover.

I'm looking at what I think is an L-pad. I'm seeing 2 of the tabs soldered together and connected to the capacitor. Does that mean that this is not actually an L-pad here, but just functioning as a variable resistor? Can I replace it with a fixed resistor?

[fpitas]

Yes, sounds like I might not have the skills and tools right now to design my own crossover.

I'm looking at what I think is an L-pad. I'm seeing 2 of the tabs soldered together and connected to the capacitor. Does that mean that this is not actually an L-pad here, but just functioning as a variable resistor? Can I replace it with a fixed resistor?

Not sure, sorry. It's been years since I used passive parts for speakers. Sounds like it's just a variable resistor, though.

[Steve Lee]

Yes, The pot is just a variable resistor sending the 4uf high pass filtered signal to both the mid and tweeter and the tweeter is padded further by the series resistor.

You can start by jumping across the wiper and high-pass end of the pot and send some audio at low volume to the speaker to verify that the pot is bad or not.

[michaelp]

Yes, I guess that is a next logical step. The edge of the pot actually looks a bit charred, and does not turn, so I'm pretty sure it is bad.

[billfitzmaurice]

I daresay even an off the shelf crossover would be better than that. Increasing the resistance with the pot lowers the knee frequency of the filter cap.

[fpitas]

I daresay even an off the shelf crossover would be better than that. Increasing the resistance with the pot lowers the knee frequency of the filter cap.

Maybe that's a high-end feature allowing variable overlap adjustment? Yeah, maybe not

[Steve Lee]

That may have been the design intent, Bill - I mean everybody needs a knob to turn in the audiophile realm . . .

[fpitas]

I daresay even an off the shelf crossover would be better than that. Increasing the resistance with the pot lowers the knee frequency of the filter cap.

As a quick and dirty thing to use an off the shelf, I guess one could Zobel the drivers to try to flatten their impedance.

[rpb]

If you momentarily connect a 1.5v battery to each driver, you should hear it make some crackling type noise. On woofers, you will see the cone move. Find out if the drivers work at all before digging in too deep.

A 4uf cap will pass only high frequencies. On my speakers, it is more common for me to use 8uf or so.

[Chris Roemer]

Do you have access to a DMM (HFT used to GIVE them away!) ?

[michaelp]

Yes, I have a multi-meter.

[chrisn]

Got Utah 12" 3 ways at the thrift years ago for $2.52. Mine have an 8" sealed back midrange with horrendous measured distortion anywhere below 2000 hz, which is kinda useless, but the woofer and tweeter are nice. I would try bypassing the Lpad/resistor thing and see if all the drivers are good. Anymore pics of the speakers?

[fpitas]

Unless you just like the nostalgia, your best bet is to replace the drivers with something modern. Driver technology has advanced enormously since those were made. Of course I'll admit I don't "get" nostalgia for its own sake, and that may be a big factor here. In which case, ignore me

[Chris Roemer]

If you tell us the internal dims of the box, and the length and i.d. of that port tube, we can tell you what freq. the box is tuned to (looks high to me!).