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Help me power up a single speaker

Mishulan

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Aug 11, 2018
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Hi all! Long time lurker here. I'm enjoying a lot the discussions and reviews on these forums. More than that, I'm a happy owner of a topping d50 dac thanks to the great work of the forum members.

I listen a lot of music on my google nest mini, mostly due to the ease of use but the sound quality is...well there isn't.
I do have a single Dali Rubicon 6 speaker that was used as a centre channel until the cinema room became the baby's room and now it sits around collecting dust.
I also have a google chromecast audio that I can use to pair the google mini with the speaker.
I'm looking for a reasonably good and reasonably priced amplifier but I have some constraints and a lot of questions that I cannot figure out the answer.
  1. First of the budget is ideally around 100-150 Euros. I'm considering something along the line of allo volt+ or allo vold+ D.
  2. I want to set it and and forget it, so no push the button to turn it on or off
    1. can I just buy any class D amp and leave it always on, or do I need an amp with auto on/off circuit?
  3. I have only one speaker (with Bi-Wiring) but most amps are stereo
    1. Can I bi-wire with a stereo amp and use one channel for highs/mids and the other channel for lows?
    2. Is this setup bad for the amp, even if it's class D? If so, will it break in 20 hours or 5000 hours?
  4. I need a way to convert the stereo signal to mono. Since this is not possible from the google mini and chromecast audio app, I've built a cable to sum it up with a couple of 100r resistors
    1. Is this acceptable or there's a better way to do it?
Not sure about the amount of power that I need but I'm not looking to break the windows. The speaker is a 2½+½-way floor stander with 88.5 db sensitivity and a recommended amplifier power of 40-200w, so 40w should be more than plenty.

Please let me know you thoughts on this, any advice is greatly appreciated!
 

DVDdoug

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can I just buy any class D amp and leave it always on, or do I need an amp with auto on/off circuit?
That's up to you. There should be no harm in leaving it on other than some energy consumption.

I have only one speaker (with Bi-Wiring) but most amps are stereo

Can I bi-wire with a stereo amp and use one channel for highs/mids and the other channel for lows?

That's actually bi-amping. (Bi-wiring is one amplifier with separate wires going to the woofer & tweeter and it's useless.) Normally a bi-amped setup has an active crossover (operating at line-level before amplification) but you can do it with your passive crossover.

If the amp has a balance control you could adjust the "balance" between the woofer & tweeter. Otherwise you probably won't get more total power so there's probably no advantage.

Is this setup bad for the amp, even if it's class D? If so, will it break in 20 hours or 5000 hours?
Sometimes it's the "shock" of turning it on that pushes it over the edge and causes a failure, so it might last longer if you leave it on.

The simplified theory is that solid state failures are random and it's equally-likely to fail in the 1st week as the 500th week. Over time, of course those probabilities add-up so it is more likely to fail some time between 0 and 500 weeks than it is to fail in the 1st or 500th week.

I need a way to convert the stereo signal to mono. Since this is not possible from the google mini and chromecast audio app, I've built a cable to sum it up with a couple of 100r resistors 100-Ohms is fine with a headphone output and it might be OK with a line output but 10K is more of a normal line-level load. There could be some signal loss depending on the amplifier's actual input impedance and if that's a problem you an try 5K or even 1K.
 

Head_Unit

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you thoughts
I think the sound will be vastly better with TWO speakers, money far better spent finding another Rubicon 6 or a different pair, and less $$ to the amp. Is Parts Express available to wherever you are? Even a small amp will drive most speakers pretty loud, even if not window-break loud.
 
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