Active Crossover Query

[mashypie]

Hello,

Can I place an active crossover query here?

Chances are I'm going to anyway...

I've been fiddling around this evening (morning) with a wee circuit simulation program

What I want to know is if a 0.86v ripple is an acceptable value or not.

I'm using an input of 5v

At 100Hz the output peaks at 4.97 v

at 1kHz the output is at its lowest at 4.04v

At 3K it rises to 4.9v

At 8.5K it drops again to 4.04v

and at 20K its 4.6v

My brain interprets this to be approx 1dB ripple. I'm not sure if I can get it better at the moment.

Is this likely to be an audible imperfection or can it be improved with more fiddling?

Phase response looks very good though!

[mashypie]

So far any slight changes I make have resulted in either the lower point falling below 4.04v or the high point rising above 5v.

I feel I have got it the best I can, but I dont know if the 0.86v is a poor figure or not....

[phase_accurate]

Is your simulation taking driver response into account as well ? Or is it just the pure crossover ?

If yes - then it is a very good result (and if the final speaker measures like that it is even excellent) but if it is just the crossover alone .....

Regards

Charles

[dewardh]

If you're stuck on analog then just read Doug Self's new crossover book (when it comes out). Otherwise look at the miniDSP crossover (worth looking at just to see what it does anyway).

[CharlieLaub]

Originally Posted by mashypie

So far any slight changes I make have resulted in either the lower point falling below 4.04v or the high point rising above 5v.

I feel I have got it the best I can, but I dont know if the 0.86v is a poor figure or not....

I wouldn't call a variation over such a large frequency range "ripple"... more like a couple of broad dips.

dB = 20 LOG10( Vout / Vin )

Vout = 4.04V, Vin = 5V, Vout/Vin=0.8,

20 LOG10( 0.8 ) is just about -2dB. 2dB variation, over a broad range of frequencies, will be audible.

-Charlie

[mashypie]

Fair point. I was working on 2.5v being the 3db point, therefore 0.8v being approx 1dB

No the simulation didn't take into account driver characteristics, I still need to find a bass unit good up to 6k and a tweeter that will go down to 1k.... :-/

[raypalmer]

Theadjacking.

Help me learn please. In the equation in the photo attached:

The ω with the little o beside mean what precisely?

[CharlieLaub]

Originally Posted by raypalmer

Theadjacking.

Help me learn please. In the equation in the photo attached:

The ω with the little o beside mean what precisely?

Wikipedia is your friend:
Angular frequency - Wikipedia, the free encyclopedia

The subscript zero indicates that this is for the corner frequency (-3dB point) of the filter function.

[zimjj]

Originally Posted by dewardh

If you're stuck on analog then just read Doug Self's new crossover book (when it comes out). Otherwise look at the miniDSP crossover (worth looking at just to see what it does anyway).

I've been interested in using an active crossover for sometime but I'm a woodworker that likes to build loudspeakers. I rely on a friend whose good at passive crossovers, who mesures my speakers and comes up with a design. I have been successful in building them though.

I've looked at a lot of crossover products but haven't heard of miniDSP before. I got on their website and was very interested in their miniDSP 2x8.

But when I read their terms of service it seems they have no warranty at all on their products, they will just cover damage in shipment. Being a foreign company that has no warranty makes me nervous.

Did I interpret this right? Do you have experience with their products?

zimjj

[juz400]

I have purchased 2 miniDSP units,
I have found them an excellent company to deal with, If you are thinking of purchasing any of their products I would say you have nothing to worry about!

I use a miniDSP 2x4 into a pair of Naim Audio NAP90.3 power amps running Focal 7W4411 Bass units and unknown HF units

I am VERY pleased with the results!

The software is EASY to use!
I ran HOLMimpulse in the background to take some basic measurements with a ECM8000
In just a couple hours I had everything running at a basic level. I will upgrade the HF units and really get stuck into measurements at a later date.

I think it took me longer to solder the Naim 4mm speaker plugs onto the 4 lots of NAC A5 speaker cable!