Utah Heritage HS1-C

[michaelp]

Well, I do sometimes have a sense of nostalgia for speakers and gear. I make guitars out of cigar boxes and cookie tins, and play some vintage guitar amps, so I can appreciate some lo-fi coloring of the sound in some situations. The one speaker that does work is nothing special on first listen...not a lot of low bass for a 12" woofer, and the highs are not very crisp. If I get the other speaker working, I'd like to spend a little time listening, but I would consider modding these in the future. The boxes are pretty sturdy and have a nice veneer.
I'll open the box up again soon and try to get some measurements...the outside of the box is 15x14x26. Looking at that photo, I think the mid speaker is 5", so that port must be almost that big, and the tube is not at all long...so I think you are right that it is tuned pretty high.
I will check and make sure the drivers are still working.

[fpitas]

Those do look nice. I can appreciate the vintage look, at least. Some internal bracing and decent drivers would turn them into nice looking and sounding speakers.

[djg]

https://techtalk.parts-express.com/f...-3-way-rebuild

[billfitzmaurice]

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

I doubt that it was intentional, more likely a matter of not knowing any better. Utah wasn't exactly of the same caliber as Altec, EV or JBL. I've seen more pictures of their input boards using the same AFU arrangement. It's a miracle that they all didn't catch fire, using 2 watt pots.

[fpitas]

I figured it was the cheapest way they could do it. These aren't exactly white van, but they're nosing into that territory.

[michaelp]

Well, the drivers still work. I bypassed the pot, and the mid and tweeter sound fine.
If I want to replace the pot with a fixed resistance, maybe I need to measure the minimum resistance of the pot in the other speaker. I don't know what the minimum resistance would be.

Inner dimensions of the box are 13 5/8 x 24 1/4 x 12 3/8 (I calculate a box volume of 2.37 cubic feet, assuming I didn't make a mistake). The port is 4" in diameter, and the length of the tube is 1 3/8".

[Steve Lee]

Min Resistance will be zero or very near zero - max will probably be 8 ohms but measure the functional pot in the good cabinet to find out what it is by disconnecting one of the wires connected to it first.

[chrisn]

Well, the drivers still work. I bypassed the pot, and the mid and tweeter sound fine.
If I want to replace the pot with a fixed resistance, maybe I need to measure the minimum resistance of the pot in the other speaker. I don't know what the minimum resistance would be.

Inner dimensions of the box are 13 5/8 x 24 1/4 x 12 3/8 (I calculate a box volume of 2.37 cubic feet, assuming I didn't make a mistake). The port is 4" in diameter, and the length of the tube is 1 3/8".

I'd try blocking the port or lengthening it, see if anything else is preferable. As far as replacing the pots, if you don't have measurement gear, a bunch of resistors and time can help you dial that in.

DJG linked to another thread further up, which itself has 2 links to applicable designs if you're thinking of modifying those Utahs