gainclone / active xo combination??

[Nuuk]

You don't say which Velleamn protection module that you looked at!

If it was the 4700, that is a stereo module which will protect both channels and give protection during powering up you amps.

The other Velleman protection modules are self-powered and you will need one per channel.

If you get too much DC on the speaker terminals of your amp, it will destroy your speaker coils. If your amp is built well, there shouldn't be too much risk but if you have expensive speakers, a protection module will provide peace of mind.

[jackinnj]

i have some boards going out for production next week -- these are like my chipclone boards, but with a dual op-amp and spaces for Sallen-key components. the way i configured it you can use jumpers to go from 1st to 4th order.

in the interim, you can always look at an XO incorporated design at;
http://www.tech-diy.com/Chipamps/jbl_LSR25P.jpg

[timsch75]

Sorry, I was looking at the Parts Express site and they only had one Velleman speaker protection circuit kit. Silly me, thought a place like that would have the whole line. Anyway, I checked out the velleman-kit site and they don't seem to sell directly. They have some local dealers, but neither of them have it in stock. I googled velleman 4700 and very little came up. Will this be that rare occasion where trying to order it will be more of a PITA than anything else?

My speakers are not expensive, but for a student, not cheap enough to forget about. Is a voice coil either fried or not, or are there stages of "burn"? I recently pulled the drivers from the original closed boxes to make a vented speaker for a project, and it appeared to me that the cone was somewhat pushed outward, although the spider was flat. Also, the fs was 64 hz rather than the published 38 hz. I know that information is not always correct for a particular driver, but just wondering if these could be symptoms of a driver that has had a rough unprotected life.

thanks

[Nuuk]

This is the mains operated Velleman 4700 with the power up delay.



The other Velleman protection module has no PSU and is smaller.

Yes, there are different degrees of cooking your speakers ranging from making the sound a bit distorted to not playing at all.

[carlmart]

Originally posted by timsch75
I've decided to go active with my two-way speakers. I have one gainclone and will need to build another.

Why don't you implement the filter on the amp itself without using an active xover?

It should be fairly easy for a two way.

What circuit are you using? Inverting or non-inverting?

Up to third order should be fairly easy to use, just at the input. On the NIGC you can also use them on the feedback of the bass stage.


Carlos

[jackinnj]

Originally posted by carlmart


Why don't you implement the filter on the amp itself without using an active xover?

It should be fairly easy for a two way.

What circuit are you using? Inverting or non-inverting?

Up to third order should be fairly easy to use, just at the input. On the NIGC you can also use them on the feedback of the bass stage.


Carlos

it's not that easy, the LM3875 has to operate with a gain of at least 10, more typically 20 -- so you are manipulating "Q" . I don't think you save anything by trying to gip an XO out of the LM3875 chip except to make it less stable.

[carlmart]

Originally posted by jackinnj

it's not that easy, the LM3875 has to operate with a gain of at least 10, more typically 20 -- so you are manipulating "Q" . I don't think you save anything by trying to gip an XO out of the LM3875 chip except to make it less stable.

It certanly is easy. Just put a high pass or low pass filter, using resistors and capacitors, at the input. How will that affect stability?

Jan Didden suggested a similar way to go about active amping using regular power amps. some time ago in The Audio Amateur.

Now if you tell me you will loss signal level with the filter or other claims that's fine. But it deserves a try.


Carlos

[jackinnj]

Originally posted by carlmart


It certanly is easy. Just put a high pass or low pass filter, using resistors and capacitors, at the input. How will that affect stability?

Carlos

I will give it a try tomorrow, but I am of the preconception that anything over first order is not going to make the LM3875 happy.