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Subs on old amps without sub-out is a bad idea


Well-known member
Mar 26, 2021
Today I decided to do a little try out swapping my post 2000 Harman Kardon with my second early 90s Denon receiver that I use upstairs. The reason is that I wanted to try if the loudness button that I definitey like with my older B&W 3 ways and Madison Bookshelves would have a positive effect on my first choice Wharfedales.

As for the outcome of the subjective experiment, the answer is no. Yes it boosted the bass and treble but instead of making it sound like an improvement it kind of put them on steroids which was ugly.

Second experiment was the subwoofer as I was thinking about maybe getting a classic receiver or amp from the 70s.

At my HK I can use the sub out but I had to connect the binding posts of speaker 2 and the sub to make it work for the older Denon.

The result was ugly. The sub doesn't cut off well, is wobbly in output and kind of bleeds in at a lower volume at the higher frequencies. Whereas with the HK it is tight in sound and cuts off straight at te preferred frequency Also the buttons which normally work with the line input didnt have any effect. So the sub out to line in really adds more control.

I can imagine peoples comments that a sub doesnt add anything special when using an amp without sub-out to line.

In terms of sound without sub and without loudness controls the HK and Denon are nearly identical. I didn't notice any sound signature difference. So back to the original setup and no 70s receiver or anything that doesnt offer line outputs.
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