Eh hem!...Subwoofers... What do ya know?

Hi @dpac996

So, if I understand correctly, you want to take an amplifier’s output as the input to the subwoofer, correct? And that this output would be shared beteen your main speaker and the subwoofer's input? If not, disregard all of this. :)


Now, onto theory and experience!

Measurements show that while the effect of an average speaker load on a solid state amplifier is small, it isn’t zero.

If you look at the Stereophile simulated speaker load,


https://www.stereophile.com/content/real-life-measurements-page-2

they estimate a minimum impedance in the bass of around 6 Ohms, while my experience says this is often in the 3 Ohm or less.

So, take a moderately solid integrated, like the Luxman 509, whose deviation from flat based on that load is here:

https://www.stereophile.com/content/luxman-l-509x-integrated-amplifier-measurements

The effect of the simulated speaker is very slight, honestly, around +- 0.1 dB. So lets say that at 3 Ohms that’s twice as much, +- 0.2 dB.


My experience has shown that this is sometimes audible, making speakers seem more demanding of an amplifier. For this reason, if you can take the signal from the preamp instead, which will have a flat impedance presented to it, you can avoid any such issues.

In other words, while I understand the math of output impedance, speaker impedance, voltage and current, my experience says that around 3 Ohms is enough to demonstrate a difference among a lot of amplifiers. I wouldn’t want to use that as a reference voltage for that reason.


PS - I own a Luxman 507ux myself. Very happy with it, but when I set up my sub, I’ll be taking the signal from the pre out. :)


Best,

E

Also ...

If your speaker is solidly above 6 Ohms across the bass, you can disregard my caution. :)

So far this turned out to be not another non sense poisoned discussion, seems subwoofers are "a thing to avoid" for the usual trolls,which is great

We are getting now into time alignment, dsp and such, keep it coming, I will take my minidsp mic and rew out of storage and do some measurements on my own system.

Thanks to the OP, I bet the short cryptic title is a deterrent 😉

@erik_squires thanks good info;

I agree the using a pre-out (or active crossover) the preferred way and so does JL audio, but in my case I am running my XLR only DAC directly into my Amp; I will need to play around in the speaker level input regime until I either get an active preamp or the JL CR-1 (preferred);

I actually sold my preamp because I found no real advantage using that vs DAC direct; So, with those funds I diverted into the JL subs and some cables (I digress); Now, it seems that plan was half baked and I would have been better off keeping the pre and stretching the budget to get the subs but I'm already way over my audio budget for the next 10 years, lol

Anyone: please take a look at my setup; do you think the subs should go on the inside or outside?

https://imgur.com/Paj46Ti

-Cheers

I would try everything. Even keeping that position and aiming at each other . You may find only one is needed there and another in the back corner . Take one of them place it on your chair and check the room for standing waves as noted before . Then place the sub where the bass was the loudest. And keep them turned down . Or the bass will sound loose .