Model 19: 416z vs. GPA 416-8C

**les winter** · June 24th, 2013, 12:43 PM

I have a pair of Model 19 enclosures and a choice to make about the lf driver. I own a pair of 416z from Valencia's. I have a pair of 16 ohm GPA drivers for the hf horn. I also have a pair of 8 ohm GPA hf drivers. So, I can build a passive x-o scaled to 16 ohms, or I could sell the 416z's and buy a pair of GPA 416-8C.

Any guess as to the best choice?

thanks
Les

**Old Guy** · June 24th, 2013, 01:19 PM

Originally Posted by les winter

I have a pair of Model 19 enclosures and a choice to make about the lf driver. I own a pair of 416z from Valencia's. I have a pair of 16 ohm GPA drivers for the hf horn. I also have a pair of 8 ohm GPA hf drivers. So, I can build a passive x-o scaled to 16 ohms, or I could sell the 416z's and buy a pair of GPA 416-8C.

Any guess as to the best choice?

thanks
Les

Build the crossover 8ohm, you can use a parallel non inductive resistor to bring the 16 down if needed, that way you can try either.

Dayton Audio DNR-16 16 Ohm 10W Precision Audio Grade Resisto 004-16

16 divide by 2 in parallel = 8 ohms

**les winter** · June 25th, 2013, 05:11 AM

Thanks OG. If I hang a 16 ohm resistor across the woofer terminals, I think the Qts gets cut in half. The simulation show a really nasty curve after that.

**alancohen** · June 25th, 2013, 08:32 AM

There would be a voltage drop across the resistor. That leaves less output voltage to drive the woofer. It would suck the life out of the sound.

**zelgall** · June 25th, 2013, 08:55 AM

How so Alan? The paralleled resistor would reduce the resistance and so the voltage drop.

**alancohen** · June 25th, 2013, 09:08 AM

Originally Posted by zelgall

How so Alan? The paralleled resistor would reduce the resistance and so the voltage drop.

Oh duh...series resistor would cause the voltage drop. A parallel resistor would result in a current drop.

It still sucks the sound out of the speaker. I just had to do this with my 300Bs. There was a woofer pumping going on at high levels and we were trying to figure out why. So I strapped a 5W across the terminals, which stopped the pumping, but it sounded like crap. We ended up making some value changes to the output capacitor as well as removing it from the feedback loop. Problem solved. But I'm not getting any design cred.