Z-680 Crossover Adjustments (hardware)

[EwoutvB]

I was wondering if anyone know how to modify it?

I tried googling it, but I couldn't find any schematics or info about it. I assume it's in the plate amp?

The only thing I've found is people incorrectly assuming there's no hardware crossover and messing with the software which really doesn't fix the problem.

Anyone?

 

[Slick5150]

There is a hardware crossover in the sub, but its not possible to replace. I researched this extensively a couple years ago and everyone agreed that it was so integrated with the rest of the sub control that replacing or modifying it wasn't really feasible.

 

[YOyoYOhowsDAjello]

The Logitech sats are 8-ohms. If you have the budget for it, you could buy a cheapo receiver off craigslist or something and set the crossover yourself that way. ~$100?

 

[EwoutvB]

Right but if I'm replacing the "headunit" of the z680 set I might as well sell the full set and replace the whole deal with a decent receiver a separate sub and build some surround bookshelf speakers myself.

Just wish I could fix this up so I could at least use the subwoofer a little, I have it nearly turned off now since it sounds horrible.

 

[YOyoYOhowsDAjello]

True

Are you using computer as source only? If so, do you have an equalizer in your soundard / integrated sound controls that you can adjust? You might be able to tone down the higher bass frequencies that the sub plays.

 

[EwoutvB]

Originally posted by: Slick5150
There is a hardware crossover in the sub, but its not possible to replace. I researched this extensively a couple years ago and everyone agreed that it was so integrated with the rest of the sub control that replacing or modifying it wasn't really feasible.

Just wondering...

Why was it impossible to replace? I assume it's just a passive crossover like an RLC circuit?

 

[PurdueRy]

Originally posted by: EwoutvB

Originally posted by: Slick5150
There is a hardware crossover in the sub, but its not possible to replace. I researched this extensively a couple years ago and everyone agreed that it was so integrated with the rest of the sub control that replacing or modifying it wasn't really feasible.

Just wondering...

Why was it impossible to replace? I assume it's just a passive crossover like an RLC circuit?

I would assume its actually an active filter being its in a device that's plugged in. Passive networks tend to be more expensive and large...especially when the frequencies in question are low...which in this case they are. Logitech will take the cheapest path in this case and go active.

Most people would say something "can't be changed" if it requires swapping out the circuitry of the device. If its worth it for you to reverse engineer the circuit and create a good replacement...go for it. However, I don't think most people have the capability to make the necessary measurements to do so properly.

 

[EwoutvB]

I'll be done with this semester in a few weeks. I think I'll take a shot at it and see if I can figure it out. I have all the tools at home and on campus to reverse engineer it.

I guess if I get it to work I'll get back here with a write-up in case anyone wants to do the same (if it works).

 

[PurdueRy]

Originally posted by: EwoutvB
I'll be done with this semester in a few weeks. I think I'll take a shot at it and see if I can figure it out. I have all the tools at home and on campus to reverse engineer it.

I guess if I get it to work I'll get back here with a write-up in case anyone wants to do the same (if it works).

The problem isn't reverse engineering it...its designing a new one for new speakers. You need acoustical measurement equipment equipment and simulation software to get that correct.

What's your goal here? If your going to lower it to stop the sub from sounding boomy I think your'll be disappointed. A small shift in crossover frequency will not fix a sub that's designed to play 40 Hz as loud as possible. It will also probably leave you with a gap in the FR since you'll be trying to extend the speakers lower than they normally would go. Now, if you replace those, I suppose that there would be some benefit to be had...but you would still have the problem with the poor sub design.

 

[Slick5150]

Yeah, from what I remember the crossover on that setup is around 140Hz due to the crappy satellites, so the sub is being extended too high and you have a very weak midrange sound. Compound that with the designed boomyness of the lower end of the sub's range, and its completely overpowering. So, as Purdue said, just lowering the crossover level to 100-120Hz won't solve either problem really, as the satellites won't extend much lower than 140Hz anyways, and the sub is still going to be very boomy on the low end.

Its too bad since the control pod is nice and small. I'd prefer having something like that on my desk over having a Yamaha receiver, but, oh well.

 

[EwoutvB]

Thanks guys.

I completely agree on the control pod part. I guess I'll wait a bit and maybe just rehaul my whole set up and maybe go to custom speakers and a normal receiver, instead of putting too much time into this set.

 

[alcoholbob]

I know the Audigy drivers allows you to manually set a crossover point. What you can do here is intentionally create a frequency hole between say, 100-180hz and see if the sub still booms (as I understand it Logitech's crossover frequency is at 150hz, not sure what the slope is).

 

[EwoutvB]

True -- the surround drivers could leave somewhat of a gap if I changed the crossover to begin with.

 

[superunknown98]

On my logitech z5300's I just taped 3/4 of the sub port. Less moving air has certainly helped tone it down, but it still sounds boomy. Even with a software equalizer, I had a hard time getting the setup to sound pleasing, of coaurse now realtek and vista took that away too.