Loudspeaker EQ

I have a relatively small living room with large speakers so sit closer to them than the manufacturer probably intended. I have fitted a switch on the underside of the cabinet (on the crossover access panel) that can reduce the tweeter output by about 2dB. The manufacturer had used a 1 ohm wirewound to feed the HPF part of the crossover which is about 8 ohms impedance including the ribbon tweeter, probably to balance the speaker response for expected use in a large room. I inserted a new 2.2 ohm w/w resistor in series with a switch that shorts it out when it is in the forward position.

PMC build a similar switch into the Fact 8 speakers I heard at Phil's place, although his were in a large room and sounded great on 0dB. For my speakers it is a subtle change that allows more toe-in without too much treble at close range.

I think the same kind of switchable treble response is common in studio monitors too. Makes sense in a smaller room where larger speakers are a bit more difficult to get right. They do often have a sense of effortless dynamics that u rarely get in smaller speakers so probably worth the extra effort.

JamesD wrote: I did something similar to my speakers when they were in a small room. Now they're in a big room the switch and resistor have been taken out again. I notice however that my old "bedroom" Pioneer receiver from 1967 (that was their first transistor design and cost the equivalent of £3000 today) has tone controls that must have served a similar purpose.... 😉

Thanks James, I'm relieved I'm not the first to retrofit this kind of switch and I too thought "treble cut" was easier in the old days!

I'd never thought much about speaker EQ before as I thought the w/w pots for tweeters in 1970's and 80's were a gimmick and I'd lazily assumed the Tannoy controls were specific to their drivers. It was the graph PMC give for their HF shaping that clicked for me - resistor in series to reduce tweeter level not change the crossover slope.