Adding sub to computer desktop system

[whovous]

I've just built a new computer and decided it was time for a major upgrade from the $99 Logitech 2.1 system I have suffered with for years.

Now, I am using the 2.0 output of my motherboard to feed a new BasX A-100 amp. The A-100 drives a pair of Airmotiv B1+ speakers. The improvement is enormous, obviously, but I have decided I want more and have an Airmotiv SE8 Flex subwoofer on order.

Now, how do I set this up? I can continue to feed the 2.0 output to the A-100 and from there feed the sub. This seems to make the most use of the A-100 volume control, but don't I give up the crossover this way?

Or, I can feed the 2.0 output to the sub and feed the A-100 from there. This gives me use of the crossover, but doesn't it also mean I will need to use two volume controls? One for the sub and the other on the A-100?

The motherboard does not offer a 2.1 option. It does offer 5.1 or 7.1 in which the sub shares an output with the center channel. I would continue to use the same output for the A-100 and feed the sub from the center/sub output. This would give me a unified volume control, but using software to control volume is a lot more annoying than just reaching 2 feet to my right and turning a dial.

Which setup makes the most sense here?

[garbulky]

You can use a Schitt Sys passive volume control before the A-100 and the sub. This way you would still have a knob that adjust the master volume. You just have to match the sub and the A-100 to be balanced in bass and set them to close to max.

[KeithL]

You would have the most flexibility if you had a separate preamp and power amp.

However, between the A-100, and the Flex Sub, you have a few different options which are pretty good.

Option #1...

You can connect the A-100 directly to the output of your computer.

You will then leave the level on the computer set to maximum (assuming it works well that way).

You will now connect the A-100 to the B1+ speakers...

And you will also connect the A-100 speaker outputs to the speaker level inputs on the Flex Sub.

You will then use the level control on the Flex Sub to set the level on the sub to match your other speakers.

And you'll use the crossover controls on the Flex Sub to get it to blend properly.

From then on you will control the level of both with the level control on the A-100.

This would be my first choice.

It should provide excellent sound, and enables you to use the analog Volume control on the A-100 for everything.

(You can leave the computer set to maximum.... or pick a slightly lower setting if it is distorted or noisy at max...)

The only down-side is that there is no high-pass filter being applied to the B1+ speakers.

(With full bass management, there would be a high-pass filter on the B1+ speakers.)

By diverting the low bass away from them, this would enable them to play louder, and use less power from the A-100.

However, unless you want to play things VERY loud, this won't be a problem.

Option #2...

Use the Line Level bass management crossover in the Flex Sub.

Connect the output from the computer to the Line Level input on the Flex Sub.

Connect the Line Level high-pass output on the Flex Sub to the input on the A-100.

This gives you full bass management with both a high-pass and low-pass filter.

Set the level on the A-100 using its Volume control.

Set the level on the Flex Sub and the crossover using the controls on the Flex Sub.

From then on you will use the COMPUTER'S Volume control as your single level control.

(Using separate controls on the sub and the A-100 would drive you crazy.)

This will work well... especially for things like gaming... where you may want more Volume.

The only downside is that you will be using the computer's digital Volume control to control the volume.

To be quite honest.... while digital Volume controls, like you will find in computers, are frowned upon in audiophile circles...

They don't sound that bad at normal to high Volume settings...

(The "loss of resolution" with digital Volume controls is barely perceptible at high Volume settings and worst at low Volume settings..... )

So, if you tend to listen at relatively high levels, and to sources like Spotify and Youtube, then it will probably sound OK.

(And, since you have a full bass management crossover, you will be able to play it louder...)

However, if you tend to listen at very low Volume settings, or to high quality music, then Option 1 will probably sound slightly better.

(This also depends on the actual sound quality delivered by your computer's sound card.)

Also, as Garbulky noted...

The best option would be to connect a high quality Volume control to the output of the computer...

You would then use Option #2 ... but without the need to use the computer's digital Volume control.

(This gives you all of the benefits of full bass management without the drawback of a digital master Volume control.)

Oct 6, 2020 9:18:56 GMT -5 whovous said:

I've just built a new computer and decided it was time for a major upgrade from the $99 Logitech 2.1 system I have suffered with for years.

Now, I am using the 2.0 output of my motherboard to feed a new BasX A-100 amp. The A-100 drives a pair of Airmotiv B1+ speakers. The improvement is enormous, obviously, but I have decided I want more and have an Airmotiv SE8 Flex subwoofer on order.

Now, how do I set this up? I can continue to feed the 2.0 output to the A-100 and from there feed the sub. This seems to make the most use of the A-100 volume control, but don't I give up the crossover this way?

Or, I can feed the 2.0 output to the sub and feed the A-100 from there. This gives me use of the crossover, but doesn't it also mean I will need to use two volume controls? One for the sub and the other on the A-100?

The motherboard does not offer a 2.1 option. It does offer 5.1 or 7.1 in which the sub shares an output with the center channel. I would continue to use the same output for the A-100 and feed the sub from the center/sub output. This would give me a unified volume control, but using software to control volume is a lot more annoying than just reaching 2 feet to my right and turning a dial.

Which setup makes the most sense here?

[whovous]

Thanks for the quick replies. I suspect I will add the Schiit SYS passive volume control in the long run so I can have bass management and a physical volume control at the same time. Digital is doubtless just fine for my low volume near-field listening, but I'd rather use a knob than a mouse to control volume.

But in the short run, I will use Option 1. One question: Did you tell me to run two sets of speaker cable from the same set of outputs on the A-100? One set to the B1+s and one to the SE8? I've never thought about doing it that way before.