Decreasing speaker efficiency?

[chris661]

Substantially is the short answer Chris. For example, using the factory parameters of an FE126E (they're fictional, but serve), Q rises from a nominal 0.247 to a rather more substantial 0.466. The effect upon the basic box alignment / FR in your favourite WinISD Pro Alpha is fairly obvious, as you can see in the attached.

Using the aforementioned FE126E with factory parameters, here's what started out as a 4th order (QB3 if you prefer) box alignment, shown in yellow, with the usual 0.1ohms series resistance WinISD assumes to account for wire, contact losses etc. Blue = 2ohms series resistance applied, pink = 4ohms, orange = 8ohms.

Yes, the effect of high output impedance was heard when we plugged some McKenzie ported speakers into a 300B SET - bass was awful. Looking in winISD, +7dB gain at 80Hz (assuming 8ohm output impedance - high, I know, but dropping to 4ohm was still a messy final response). Yuck.
We decided some speaker designs need a low output impedance. Those particular speakers certainly did. Others certainly seem more lenient.

Chris

PS - also sorry to hear of the tumours, has the surgery gone ahead yet?

 

[503Timber]

I decided to just build new cabinets (I wanted to anyway) I'll have a listen after they are in their new home and hopefully I won't have to do a thing but enjoy them. I have my material and hopefully I can get these done before the surgery (which will be about 6 weeks from now....thanks for moving it again doc )

I'm just not finding myself motivated to actually start the project......why can't these darn cabinets just build themselves.

Thanks for the "warm fuzzies" guys.....I'm sure everything will go as they should, good or bad.