Sub with SL3s

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MickyP

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Hi and apols if this has been answered before.

Can I run a sub with my SL3s, would it be worthwhile and how does it connect? Any do any makes/models spring to mind?! Amp is a Musical Fidelity M6i.

Thank you loads!
 
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JonFo

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Thanks for listing the integrated amp used, as I was able to read the specs .

The 6i has a preamp out, but no preamp in, which is the ideal topology, so integrating a powered sub will be difficult, as there is no way to divide the frequencies ahead of the built-in amp.

To correctly integrate a sub for a 2.1 setup, the preamp output should first go into a two-way crossover and then the high pass output feeds to preamp in of the unit. The low-pass then feeds the LFE-input of the sub amplifier.

Even though the 6i has a tape monitor loop, which allows one to achieve basically the same thing, the problem is volume control, as the tape-out is full-signal and not affected by the volume setting, thus the sub gets the full level signal at all times. If you only ever listen at one volume level, you could adjust, but that's not likeley.

If you use the speaker-level output to drive the speaker-level inputs of a powered sub, then that works to a degree, but now you have doubled up low-frequencies, which is bad.

If wanting to do a 2.1 setup right, you'd need different gear. And I'd go for a model that supports 2.1 natively. Or use separates.
 

MickyP

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Hi JonFo

Thanks for reply. I am clueless in this field, apols. How it connects specifically. I see some (including ML ones) which use speaker cables, but ultimately I was hoping for something wireless which avoided all of the cabling. But that's not possible, right, without a different amp or pre-power amp combo? This isn't an option really. :-(

In your opinion would going the sub route prove of musical value? I suppose that one is key!

I may be able to get the amp modded if I know what to ask for, as we have a MF wizard in the UK.

Regards

Mike
 

JonFo

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I may be able to get the amp modded if I know what to ask for, as we have a MF wizard in the UK.
The mod is pretty simple, the request would be:

I want you to modify the Tape Rec connectors to function as a 'Preamp Input', so we can create a processor loop for an external crossover for a sub.

I assume the loss of the Tape Rec function is not a big deal, but maybe you have an RtR deck 🙃

In your opinion would going the sub route prove of musical value? I suppose that one is key!
You are asking the guy who has four subs in each of his two systems, and the four in the HT were designed and built by myself. So with that ...
Yes!!! as the optimal positioning of an ESL speaker generally results in poor low-end performance. So adding one or more subs (more is better as they help smooth room modes) allows the system to play lower.

On music, even something as simple as solo piano, the low-end is critical to the sense of weight and depth of the instrument.
And on pipe-organ recordings, totally transforms the experience.
I'm a big Prog Rock fan, and that has some serious low-end demands from well recorded and produced bands.

BUT, how one integrates a sub is important!
This is why I did not tell you just wire the speaker outs of the 6i to the speaker-level inputs of a sub and call it a day.

To properly integrate a sub, you need to remove the low-end feeding the mains, as that has two benefits:
1- It lightens the load on the amp, and reduces the effort the woofer expends, resulting in less distortion from the woofer.
2- By removing the lows from the units placed in less than ideal locations for those frequencies, you minimize room modes.

Now, you need to figure out how to create a crossover between the pre-amp out and pre-amp in connections.

The right way to do that is to deploy an active 2-way crossover that both splits the signal, applies delay where needed, and performs EQ where needed. But that is technically challenging to set up, not the wiring, but the config and tuning steps.

So a much simpler, although less refined approach would be to take the pre-amp out signal via a splitter cable that has one end going to the low-level signal inputs of the sub (most subs have RCA line-level inputs for L/R) and the other going into a passive high-pass filter connector that then connects to the pre-amp in connectors. On the sub, set the crossover to match (70Hz in the example here), and adjust levels and polarity so the system is balanced.

See, easy 😉
 

iluvboxing

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Hi and apols if this has been answered before.

Can I run a sub with my SL3s, would it be worthwhile and how does it connect? Any do any makes/models spring to mind?! Amp is a Musical Fidelity M6i.

Thank you loads!
Hello MickyP,

Yes, you can run subs with any speakers that you want. Your SL3,s are similar to my Aerius i’s, so I would imagine the REL T/9X would be a good paring. You may want to consider a dual sub configuration if your budget allows for it.

I currently run a REL HT/1205 for LFE and add low end to my audio, but, I’m upgrading to dual T/9X.

Link:
 

MickyP

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Hi Jonathan

Very comprehensive reply.

Thank you so much.

Mike
 

Brandon Hartwick

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You don't absolutely need to high pass your front speakers, many, many people simply run a subwoofer with a built in amplifier off the pre-out on your integrated amp.

Check out REL acoustics, they seem to be popular with the highfi guys.
 
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