Can a chipamp drive these speakers?

[MeathooK]

I'm currently in the process of building speakers, and have recently finished designing the crossovers and would love to pair them with a chipamp. Only problem is, the system impedance drops JUST below 4ohm around 5-7 kHz. Would this be a problem for the 3886? If so, is there an amp you could suggest to use that wouldn't have a problem with this impedance drop? I've attached the FR/Filter/Impedance plots just so you can visually see what I'm talking about. Thanks!

(Ignore the arrow in the FR plot)

[h_a]

Hi,

almost any 2.5 way speaker or any of those D'Appolitos usually drop to some extent below 4 Ohms, no big issue.

You're even in the lucky situation this happens far in the high frequencies where almost no power is needed.

Further, the chipamp does not care at all about impedance, all the little bugger is interested in is current demand (power dissipation) and that shouldn't be a problem at all. Worst thing that may happen is you don't get maximum power, but as already said I think that's unlikely to happen at all.

I wouldn't worry at all about that.

[AndrewT]

I think your impedance curve suggests to me that you should design for a 6ohm speaker rather than an 8ohm speaker.
Vac 22V to 23V would probably be about right.
But do use big heatsinks.

Have you considered using 3 chipamps to drive the crossover?

[madisonears]

The dip to 5 ohms at 80hz will be more of a problem, if there is one, because that's where the system needs far more power. As Andrew suggested, use a slightly lower voltage xformer and you should be okay with good temp management.

Peace,
Tom E

[MeathooK]

I think your impedance curve suggests to me that you should design for a 6ohm speaker rather than an 8ohm speaker.

Already have the speakers which are all 8ohm or else I might consider it

Have you considered using 3 chipamps to drive the crossover?

I was planning on running a 3886 setup either dual mono or stereo. Any reason for 3 chip amps?

Thanks for the suggestion on the lower voltage transformer guys, looks like I'll be building one in the near future

[h_a]

the speakers which are all 8ohm

Naah, Andrew was talking about nomenclature, in his opinion your speakers are more like nominal 6 ohms. As long you don't have to write specifications for your speakers this has no real meaning.

Are these chipamps not properly temperature protected or why all the fuzz about that high frequency dip?

Could it be that you are not aware that above 1kHz energy content in music drops roughly with 6dB per octave?

[AndrewT]

Hi,
I have not seen the crossover for this 3way 8ohm speaker.
I can see that the impedance dips shows minima that are almost certainly below the Re of the drivers used.

This tells me that the corrections applied in the crossover have some/many parallel paths to the drivers that effectively lower the overall impedance seen by the amplifier/s.

I stick with my suggestion that the amplifier be designed for a 6ohm speaker load and not for an 8ohm load as might be implied by the drivers used.

It is the complexity of the crossover that makes this design target a necessity.

Now to separate amplifiers for each section of the cross over.

If you test the impedance of the bass only part of the crossover with the driver attached you will find that the LF end of the impedance curve is virtually identical to what you have already posted. The mid and HF end will rise to considerably higher impedance than shown.

Similarly the Mid section and the Treble section will show out of passband impedances that are much higher than the pass band impedances.

These increased impedances out of band reduce the loading on the amplifier. The amplifier has an easier job driving one section of the crossover than trying to drive the whole crossover.
This separation of amplifier and crossover into sections is called Bi-amping or in your case Tri-amping.
The amps perform better, particularly if they are already stressed with the "whole" load.

For the sake of two extra chips and a few components, it's worth experimenting to hear if the amps/speakers combination sounds better Tri-amped.