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Uncertain about crossovers


chriswhotakesphotos

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Hello everyone,

 

I'm thinking I might shop for a subwoofer for my floorstanders, and before I go buying or looking at anything, I'm a bit uncertain about crossovers. Specifically, I'm not sure what kind of hardware to use for it. Should I be looking for a dedicated crossover unit, or should I be using a preamp that has a crossover built in? I understand some graphic EQs have crossovers, but I've also heard that some of these can diminish the overall sound quality. Web searches have been a bit inconclusive so far; there are plenty of guides on how to configure one's crossover frequency, but they don't speak very much about what kind of hardware is best for it. Thanks in advance for any advice!

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I have a pair of Synergy F-20s, with an Adcom GTP-500 pre and GFA-535 amp. At the moment, the primary usage is music, but they're occasionally used for video games as well. I definitely don't want to switch to an HT receiver; I understand they tend to have built in crossovers, but I'm very happy with how the Adcoms sound for music.

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Will that be an ideal way to go about it, or do you think there will be some phase issues where the speakers and sub overlap? As strong as the F-20s are for bass (surprisingly strong!), I was hoping to take some of the burden of their bottom frequencies off of them! My dad suggested getting a Behringer (or similar brand) rack mount crossover like he uses in his business (a dance studio), so I may go that route, though I'm a bit concerned that adding to the frequency path will come at a cost for a home hifi setup. Is this a legitimate concern?

And as a matter of fact, I'm talking to someone about buying their Synergy Sub-12 right now. Should be a good match!

 

Edit: It turns out the Sub-12's speaker passthrough actually has a high pass set at 100hz. This should be a good start, but I feel it'll be a bit high given the capabilities of both the speakers and the sub. Perhaps I should find a good graphic EQ and use that in conjunction with the sub's low pass to get the best results?

Edited by chriswhotakesphotos
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Will that be an ideal way to go about it, or do you think there will be some phase issues where the speakers and sub overlap? As strong as the F-20s are for bass (surprisingly strong!), I was hoping to take some of the burden of their bottom frequencies off of them! My dad suggested getting a Behringer (or similar brand) rack mount crossover like he uses in his business (a dance studio), so I may go that route, though I'm a bit concerned that adding to the frequency path will come at a cost for a home hifi setup. Is this a legitimate concern?

And as a matter of fact, I'm talking to someone about buying their Synergy Sub-12 right now. Should be a good match!

 

Edit: It turns out the Sub-12's speaker passthrough actually has a high pass set at 100hz. This should be a good start, but I feel it'll be a bit high given the capabilities of both the speakers and the sub. Perhaps I should find a good graphic EQ and use that in conjunction with the sub's low pass to get the best results?

 

 

I gave you the best way to go about it already.  Re-read post #4.  If your mains are on the same plane as your sub you won't have phase issues.  Even if you did, a plate amp with a phase KNOB (not switch) will get you where you want to be.

DON'T use the speaker pass through option, wire it as I described above.  Your mains will get a full signal that way.

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I don't doubt that it will work that way! But part of the reason I want a subwoofer is so the speakers themselves won't need to produce nearly as much bass. Since they only have 6.5" drivers, it is no doubt some burden on the midrange to have to do so much. They do an excellent job, but when listening loudly, I think it would clean up the mids a bit more to separate some of those frequencies out.

 

I think what I'll do is try it set up in different ways to see what sounds best. Perhaps if my preamp's tone control for bass doesn't reach too high, I can configure it that way without extra equipment. Worst case scenario, I'll just wire it parallel like I have with my bookshelf set. It'll sound good either way, but I think it would benefit both the sub and the mains to delegate.

 

If everything goes according to plan when I meet the Craigslist guy on Saturday, I should have some results to post about!

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So I've got my Sub-12, and it turns out that the manual lied about having a built-in crossover! Perhaps I interpreted it wrong, but the passthrough absolutely doesn't cut the speakers at 100hz. I also didn't realize that by not-full-range, you meant the sound would be of lower fidelity. I thought I might had been kidding myself when I believed the speakers sounded worse when passed through the sub, but certainly enough, using the sub's line in and plugging the speakers directly back into my amp brought things back in order tremendously. (The Craigslist seller also included a pair of beefy RCA cables with the sub, which didn't seem necessary, but I'd venture to say they might sound better than the cheap ones I used to plug my pre into my amp before)

 

Even though I can't use a crossover to cut some of the low end to my speakers as I'd wanted, the sub pairs with them quite well. I've set the filter to 50hz and used my ears (and some sine waves) to blend it in and set the gain. The Sub-12 definitely doesn't play nice with small speakers (the seller tested them with his pair of Audioengine A5s, and the sub sounded very separate from the sound of the speakers), but it disappears well with the F-20 floorstanders. The spec sheet also lied about it hitting 24hz, but I'm happy enough with everything else it does to not mind so much. Not bad for a $100 Craigslist find!

 

After hearing the effects of a weak link in the signal path, I'm not sure if I'll continue looking for extra equipment to filter the speakers. I might explore MiniDSP if I can find enough people saying good things about it, but we'll see. A crossover seems like the sort of thing more preamps should have built in, if you ask me! Either way, I'm quite pleased with the performance I'm getting with my new subwoofer. Thanks for the help!

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