Amp bottom frequency + sub question (secondary system)

[AJM1981]

My primary system is functioning as it should and currently I am tinkering around a little with a secondary setup of small bookshelves, an old world amp and sub upstairs. So it is cable spaghetti time.

As today I thought.. why not, and took the old Magnat sub from the attic. It basically only has a volume control and there is not much to customize but it might serve the purpose of completing the bottom end of the bookshelves really well so a cut off frequency is not really needed here (for any other bigger speaker this particular sub is not as good.) as this one seems to be made for the smallest of speakers.

I am doubting about either giving my recently replaced Harman Kardon or older Denon amp away with my B&W standmounts so I do a little testing on what is preferrable to keep for the sub and speakers.

As the Denon has a loudness button and the bookshelves get a little necessary kick in the treble at low volume listening I would maybe keep that one. But it still can go either way.

I just discovered that besides doing very well as a bass extension either the sub or the amp "might" have a bottleneck in preventing it from digging into real sub frequencies as my smaller B&W does better in that.

The Denon pma720 receiver is one from the early 90s and from the specs online I once found that the amp had an odd low end frequency that started much higher than I expected the average amp to start. Now I cannot find that reference back but I will keep it in mind.

The sub seems to do it well as a woofer of a larger speaker in this setup but seems to miss the really tight low sinus waves or rumbles as it kind of bloats what's above it.

In this case I might maybe go for the HK amp with sub out and a broader frequency range or is there another way to get more out of the Denon?

 

[insider9]

Am I reading this right? You're sending full signal to a sub that doesn't seem to have a controllable crossover. This mean sub will go much higher into midrange than you'd want it to. The only way to control it is to have it playing quietly enough at which point it won't do what you want it to.

Best way to deal with it would be to have a receiver that can only send sub appropriate frequencies (not full range signal). Have a look at a decent AV receiver on second hand market. One of the big Sony, Yamaha, Denon ones can sound brilliant and some would have the functionality in question.

 

[AJM1981]

Am I reading this right? You're sending full signal to a sub that doesn't seem to have a controllable crossover. This mean sub will go much higher into midrange than you'd want it to. The only way to control it is to have it playing quietly enough at which point it won't do what you want it to.

Best way to deal with it would be to have a receiver that can only send sub appropriate frequencies (not full range signal). Have a look at a decent AV receiver on second hand market. One of the big Sony, Yamaha, Denon ones can sound brilliant and some would have the functionality in question.

The cut off seems fine here. The bookshelves' bottom end continue well at the top end of the sub giving the illusion ot having bigger speaker.

I only get the idea that there is more to get at the bottom half of the sub itself.

I just found the frequency response of the amp, it is 20hz to 20khz. That is checked off being fine as the sub ranges from 22hz onward but the HK receiver also seems to cover 10hz onwards.

Maybe there is not much more to it. Maybe there is something to win in connecting it to the HK's sub out with Rca instead of the Denon's binding posts with speaker cable. It made a huge difference with my B&W sub, but it is a totally different sub too as the speaker cable bypassed a lot of necessary controls. On the magnat there a basically no controls to start with