Increase total Speaker Impedance -- Potential Solution


Hi All, 

Years ago I asked about using a resistor to increase the total impedance of a speaker -- I know that's a bad idea now because Impedance is NOT the same as resistance. I did get a pair of Paul Speltz's Zeroformers and they are great!

However, reading more about this, I thought another, more cost effective solution. Why not just buy a low cost, 4 ohm speaker, remove the diaphragm inside, and series-wire it? I'm reading some of the Zeroformer's technical documents and it sounds like it's rather similar to a speaker coil that doesn't produce any sound. Therefore, if I just series-wire a 4 ohm speaker to my existing 2 ohm speaker, wouldn't the total ohm seen by the amp be 6 ohm? 
angelgz2

Showing 1 response by angelgz2

Hello! Thanks all for your input and thanks  @almarg  for your expertise again!

The reason I needed to figure out a way to increase the impedance of my DIY unit is that the Zero Autoformers will soon have another use. I purchased a tube amp to be used with my Martin Logans and I heard the electrostatics' impedance drops really low and a pair of Zeros will help big time. Hence, the Zeros will now be connected to the electrostatics instead.

I'm not ready to chip up another $500 for another pair of zeros since if that's the case, I'd rather just sell all my drives and just buy another pair of speaker and kiss the DIY goodbye. Luckily, I found a creative way to re-wire the speaker so the impedance is now 4 ohm instead of 1.6 ohm.

How I did it:

Originally, almost all of them have separate crossovers and wired in parallel. Now I have three crossovers:

1x 2 way crossover at 2000hz
1x 1 band-pass 800-5Khz
1x low pass 800hz

Speakers:

1x Dynaudio D76AF
1x Dynaudio 15W75 Esotec
1x Dynaudio 17W75
1X Morel Supreme Tweeter (forgot model number, but ideal crossover I recall was 1800hz)
1X Dynaudio MW172 (8 inc)
With the exception of MW172, the rest are 8 ohms

2 way crossover high-pass connection goes into Morel Tweeter. The same crossover, low-pass connection goes into 15W75 and 17W75 wired in series. I understand they are not identical, but I see they have similar frequency response plots. Then, still using the same low-pass connection, wire the MW172 parallel to the 15w75 and 17w75 series, along with a series 1.5 ohm resistor. So in the end, I have all the woofers on the same low-pass connection of the 2 way crossover. However, the MW172 is crossed over a second time with the 800 low-pass filter. The D76AF stands along with the band-pass filter. Overall impedance showing in my multi-meter is 4.1 ohm.