I am going to measure them up and do a sketch plus I will do more pics.
They were really cheap from new...which raises my concerns.
The chasm of a port looks big but it is part of a flare that thins down towards the rear of the box it's a sort of flared bass reflex port, it then folds at the back travelling along the rear of the box before opening up into the rear area of the driver...If that makes sense
wow... i am learning....you here about things like damping of an amplifier..but I never thought you could actually hear it having such an effect in the real world....the Chevin amp definitely works better.
The damping factor of the iNukes is rated at >140 into 8 ohms. Anything over about 30 or so is likely to be unnoticeable (and I'm sure many listeners would have problems noticing the effect of a damping factor lower than that).
If the iNukes have a weak point, IMO apart from unreliability (I've got two awaiting repair), it's more to do with their response at high frequencies not being load-invariant, but that's quite simple to plan around if needed (e.g. conjugate filter to flatten impedance above about 3kHz or so).
From my experience there is a huge difference between a low damping factor and a high df amp especially on subs.
Personally I will not use anything below 300 on subs.
And I know why.
The high freq "problem" is inherent in class d amp design, not only the inuke and because of the necessary output lp filter.
Mikeydude,
You also need to learn to separate "real world" BS from actual facts.
The gauge and length of the wire connecting your speakers will have far more effect than the difference between the NU6000 damping factor of > 140 @ 8 ohms compared to one of 500 or 5000.
The difference between damping factor at the speaker using an amp with 100DF vs 5000DF using 50 feet of 12AWG cable is 44.75 to 50.25, only about a 12% difference.
Use a 100' 12AWG on a 2 ohm load with an amp with 500 ohm damping factor, and it drops to only 6.22 at the speakers, not good, we'd like 20 or above for PA use.
bennettprescott.com/downloads/dampingfactor.pdf
Art
Then you'd better be soldering those sub drivers directly to the amplifier's terminals, because even the impedance of the speaker cable and the across the connection at the terminals is going to reduce that significantly. Just 0.1 ohms of impedance between the amplifier and the speaker drops the damping factor below 100 ;-).
Some good reading - Damping Factor with Calculator
It is inherent in SOME class D amps. The Alpine class D amps I have in my car don't care less if the load is between 2 ohms and 8 ohms. It's all in the design. The Behringer uses a cheaper approach that should be fine for pro audio use (within some limitations of course). And a conjugate filter is easy to put together if one is picky about those things.
Of course df will drop over cables and connectors but it plays a major role with what value you start with in the first place.
This can easily be verified by yourself even.
Theory is just, well theory.
What is Alpine doing differently?
No it does not, and in any case what matters is what the driver sees at its terminals, as that is the transducer that's converting electricity to audio signals. Please have a read of the link I provided.
Not quite sure, but many class D amps these days are load-invariant for their rated loads.
I know the math, etc. and I read a lot about it.
This didn`t prevent me from doing my own practical research though.
For me a low df amp like below 300 just doesn't cut it on the subs anymore sq wise.
Oh right....so...there could be design issues?...what sort of size would you expect please?
OK that's great info...many thanks. I can easily remove some of the port as it Flares out this will increase the area but greatly reduce the port length...but I could add length to the port by then adding pieces in parallel to the rear of the enclosure
See if you can get the TSP (Thiele-Small Parameters) of the drivers in question then simulate and modify the enclosure to end up with something worthwhile.
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