Passive crossover on z5500?

[tonksiee]

The crossover is set at 150hz which is too high for a sub to be playing for my liking. Ive looked and there no simple way to modify the crossover to around 80hz, so i was thinking can i not just buy a passive crossover set it to 80hz and place it between the amp and the sub? That way the logitech crossover will send 150z to the sub but the extra passive crossover will lower it down to 80hz.

 

[NutBucket]

Isn't the amp in the sub itself? That would make it a bit difficult to modify.

Unless you're feeding 6 discrete channels from your PC in which case you could probably insert one in-line.

Or, just get a real audio setup

 

[YOyoYOhowsDAjello]

What's going to produce the 80Hz to 150Hz part of the spectrum them?

 

[tonksiee]

The amp screws into the back of the sub enclosure then the wires just come from the amp and go through the closure into the back to the sub, just screw the amp off and you can get to them easily. I've tryed even if you directly connect 6 channels it still filters it :\

And i ent got the money

 

[tonksiee]

What's going to produce the 80Hz to 150Hz part of the spectrum them?

The satalites, well im going to upgrade them with sony bookshelfs.

 

[NutBucket]

Your plan is flawed because you'd have to lower the satellites' high-pass filters to 80 Hz. Otherwise, you'll effectively kill the frequency response of your setup between 80-150 Hz. Let me know when you get that worked out.

 

[tonksiee]

Your plan is flawed because you'd have to lower the satellites' high-pass filters to 80 Hz. Otherwise, you'll effectively kill the frequency response of your setup between 80-150 Hz. Let me know when you get that worked out.

I ran a frequency generator on my computer and the satalites go down to 80hz.

 

[Harvey]

I ran a frequency generator on my computer and the satalites go down to 80hz.

The satellites may go down to 80 Hz, but if they're too small, they won't reproduce those frequencies, and if they're not designed or intended for that duty, you could burn out the voice coils.

What is the spec for your sub? If it's spec'ed to go up to 150 Hz, you're better off leaving it there. It probably has a built in low pass filter at the input to block frequencies above its intended design limit.

After all of that, a passive crossover, especially one greater than first order (6 dB/octave) wastes power. If it means all that much to you, a good active crossover is a far better solution, but then, you'll need separate amps (bi-amp) for the high and low bands.

 

[tonksiee]

The satellites may go down to 80 Hz, but if they're too small, they won't reproduce those frequencies, and if they're not designed or intended for that duty, you could burn out the voice coils.

What is the spec for your sub? If it's spec'ed to go up to 150 Hz, you're better off leaving it there. It probably has a built in low pass filter at the input to block frequencies above its intended design limit.

After all of that, a passive crossover, especially one greater than first order (6 dB/octave) wastes power. If it means all that much to you, a good active crossover is a far better solution, but then, you'll need separate amps (bi-amp) for the high and low bands.

I used the tone generator to see whats the lowest signal the amp sends to the satalites, the bookshelves have a frequency range from 80-5000hz so they should work good.

I don't know the spec of my sub but no sub should be playing at 150hz should it? I've read that logitech set the crossover that high because the satalites have a bad mid range, which they do. But im replacing them so i dont need the sub to be playing frequencys which the bookshelves can handle perfectly fine.

How much power would a passive crossover use? And it doesn't matter if the sub has a filter to stop high frequency's coming in, it plays 150hz fine and i want to lower it to 80hz.

 

[sdifox]

Waste of time. The Sony bookshelves will demand more power than the amp/sub cube can provide.

 

[NutBucket]

And don't forget, just because the bookshelf speakers are spec'd to 80Hz doesn't mean they'll reproduce those low frequencies well.

Honestly, just use your setup the way it was designed and save up for a new system.

 

[tonksiee]

Waste of time. The Sony bookshelves will demand more power than the amp/sub cube can provide.

Ive seen few people do it on other forums and apperently its a good improvement? They will still be an improvement wont they, sound quality wise? Just wont be getting there full potential.

 

[sdifox]

Ive seen few people do it on other forums and apperently its a good improvement? They will still be an improvement wont they, sound quality wise? Just wont be getting there full potential.

problem is sooner or later the amp will clip. Those things are designed to output x amp of current and since they know the load being driven, there usually isn't a lot of reserve. You could upsize the caps (if there are any reserve caps that is) to mitigate this, but again, it's a waste of time.

 

[tonksiee]

problem is sooner or later the amp will clip. Those things are designed to output x amp of current and since they know the load being driven, there usually isn't a lot of reserve. You could upsize the caps (if there are any reserve caps that is) to mitigate this, but again, it's a waste of time.

Clip? Reserve? Caps? I dont know much about amps lol.

 

[Harvey]

I used the tone generator to see whats the lowest signal the amp sends to the satalites, the bookshelves have a frequency range from 80-5000hz so they should work good.

I don't know the spec of my sub but no sub should be playing at 150hz should it? I've read that logitech set the crossover that high because the satalites have a bad mid range, which they do. But im replacing them so i dont need the sub to be playing frequencys which the bookshelves can handle perfectly fine.

How much power would a passive crossover use? And it doesn't matter if the sub has a filter to stop high frequency's coming in, it plays 150hz fine and i want to lower it to 80hz.

I design audio electronics. Not intended as any kind of flame, but you need a better understanding of how speakers and crossover systems work before I can answer your questions. When you've done some homework, you'll be able to search the web for better info and understand the answers you find.

Good luck.

 

[sdifox]

Clip? Reserve? Caps? I dont know much about amps lol.

clipping is when your speakers want power and your amp can't keep up. That will distort the sound and overheat the driver element. Tweeters tend to be the first ones to go. Reserve Capacitors are capacitor tasked to provide temporary power boost in case your amp needs that extra power.

If you don't know much about amps, why are you mucking with the crossover at all?

 

[NutBucket]

Uh, caps on the ouput of an amp aren't going to help mitigate clipping.

So Harvey, what kind of audio electronics do you design?

 

[YOyoYOhowsDAjello]

The satalites, well im going to upgrade them with sony bookshelfs.

If you're already replacing the speakers, I would recommend picking up a receiver as well. You can probably find something new for $150 or used for cheaper that would handle your needs.

If you are already connecting to the z-5500s digitally, then you'll have an easy time finding a cheap receiver that will handle your computer tasks.

You'll be able to set the crossover point with a decent receiver and you'll still be able to hook up the Logitech sub to it. With the lower crossover point set at the receiver, your new speakers will get the frequencies you intend to send them and the subwoofer will only be sent lower frequencies from the receiver, so its higher internal crossover point will be irrelevant.

If you're hooking up via analog, you'll need a receiver with a multichannel input. You also may run into issues with the crossover this way, since the multichannel analog input on a receiver may disable its own bass management system. You'd then need to rely on your soundcard to do bass management (if it has this feature).

EDIT: You said you determined that the z-5500 sats were still producing sound at 80Hz.
The z-5500 crossover is set higher, so the signal send to the satellites is progressively weaker as the frequency lowers from the crossover point. At 80Hz, the satellites will still be being sent something, but it's much lower in volume than it would be at 150Hz.

Even if you get speakers that can handle bass better, the z-5500 sub will still be using a 150Hz crossover with them. You could put another filter in the z-5500 sub so the subwoofer doesn't play much above 80Hz, but the satellite amplifiers in the sub will still be sending out signals to the satellites to mesh with the default subwoofer assuming that the 150Hz crossover is still in place.

So, you'll get reduced output from the system in the 80Hz - 150Hz range. The output in this region will not be "0", but it will be less than you want it to be. The satellite amplifiers will not know that you now want them to fully take over the 80Hz to 150Hz range, so they'll still start reducing the output sent to the satellite speakers starting at 150Hz and on down.

 

[slashbinslashbash]

^^ Agreed. If you're already spending the money on bookshelf speakers, sell the Z5500 and buy a real receiver. You can pick up a used, decent quality Dolby Digital receiver for $100 or less. You will probably get more bass out of a receiver+bookshelf system than you will out of the "subwoofer" that comes with a PC audio system.

 

[0roo0roo]

Second guessing the engineers that made those z5500 is a bad idea, they put that cross over at that point because those computer speakers are weedy little suckers that have sats that are too small to handle the lower mid range by themselves. So its inevitable the cross over will be set higher. As said, any decent system willl have bigger bookshelf like speakers..bigger drivers on everything. Sacrifices are made with the z5500, just no way around it.

 

[yuppiejr]

Is the subwoofer's crossover what you don't like or is it resonance in the sub box or a "hot spot" in the frequency spectrum around the sub port's tuned frequency, perhaps, that you're not liking? Having disassembled a Logitech 2200 subwoofer after an amp went south recently I noticed a total lack of polyfill or other resonance dampening material in the cabinet (which is sturdy but somewhat thin MDF). Adding some 1/2" foam to the insides of the box plus a half bag of polyfill did wonders to smooth out the response in mine... though I also replaced the amplifier with this Dayton plate amplifier

This whole project sounds like a cluster-f... waiting to happen though... ripping apart a $400 set of computer speakers minimal knowledge of how speaker frequency response "should" work with limited factual knowledge of crossover network design, etc... is just going to make things worse. The Logitechs are a closed box system designed for asthetics and "low fiddle" factor to work as provided without the sort of user customization you are looking for. Best case you will end up spending a bunch of money and end up with a system you still don't like.. worst case you'll trash the amp or some other component and end up with a $400 loss. I think you would be far better off with separate components allowing both a higher level of performance and greater customization in exchange for larger bits and pieces if you want to stick with the same price point.

A better path:

Sell the Logitech speakers before doing any further damage... skip buying lunch for a few days to save the difference in what you paid versus what you sold them for and reinvest.

Example:

BIC Venturi V1020 10" powered sub ($150)
Dayton B652, 6 1/2" 2 - way bookshelf speakers ($25 per pair, buy 3 pairs)
Sherwood RD-6513 5.1 HT reciever w/ HDMI switching ($170)

Total damage - $395 shipped.

The speakers can be upgraded later as you see fit.... at $25 a pair you can replace them later, mod to your heart's content to squeeze a bit more performance out of them or learn about speaker design, donate to a friend, etc... The Sherwood reciever is basic but does HDMI switching and the standard DD/DTS digital decode duties on a budget. If you have an extra $50 to spend you might consider stepping up to the Pioneer VSX-520 to pick up a couple of nice upgrades including the new HD audio decode formats, microphone based room calibration and an extra HDMI input (total of 3.. supporting HDMI 1.4). The sub should be good for much longer which is why I'd step up from one of the cheaper Dayton/Sony/MTX models into the BIC. You can also take the entire setup into your living room and use it for a respectable home theater if you so choose later.

 

[tonksiee]

Thanks for the responses guys, i think i will buy a new system with seperate parts. I saw this sub on ebay http://cgi.ebay.co.uk/LTC-ACTIVE-HO...iFiSpeakers&hash=item51934cba32#ht_5431wt_942 and i was just wondering, it has a high level in and out. What is this for? I was thinking could i connect 2 bookshelves to the high level out? Im going for a 2.1 setup as i only use my speakers for music now.

 

[NutBucket]

The speaker level in and out let you wire this in-line with an existing amp/speaker combo. This way the the low frequencies will be sent to the sub and speakers will be high-pass filtered. You'll still need an amplifier for your bookshelf speakers.

 

[tonksiee]

The speaker level in and out let you wire this in-line with an existing amp/speaker combo. This way the the low frequencies will be sent to the sub and speakers will be high-pass filtered. You'll still need an amplifier for your bookshelf speakers.

Ok what would be a good cheap 2 way amp, i can only find 5.1 amps.

 

[yuppiejr]

Ok what would be a good cheap 2 way amp, i can only find 5.1 amps.

I think we need more info if you want good advice - your requirements seem to be changing a bit which may alter the advice you get: Budget, long term upgrade path, your location (shipping/tax/what country are you sourcing product in/etc..).

Do you ever intend to upgrade to a 5.1/7.1 surround system or is this truly a single purpose setup (2.1 music)? In budget priced stuff the cost increase from stereo to 5.1 is usually offset by the significant number of features you get in addition to long term flexibility. Also, most stereo recievers to not include a preamp output for your subwoofer meaning you're going to drive it with speaker level outputs which work but will not be as clean as preamp input typical in any x.1 reciever.

Here's an example of a budget stereo reciever:

http://www.bestbuy.com/site/Insignia...&skuId=9693507

Also, give the BIC Formula (F12, etc..) or Venturi (linked above) series subwoofers a look - great bang (literally) for the buck for a great product. Not sure about that unit linked on eBay, the concepts you asked about made it a good example but I can't speak to the brand.