604E DCR

[selmerdave]

I have been enjoying my recently completed 604E's, they really sound wonderful, but as I have been finding out more about them I'm beginning to wonder. When I measure DC resistance at the driver terminals (with everything disconnected), I get 10.0 for the woofers and 9.2 for the tweeters. This is somewhat higher than what I believe I should have according to the specs available, more like 7.0 is what I should see. Does this suggest that these were redone with the wrong voice coils?

Dave

[selmerdave]

Sorry to bring this back up, but I figure somebody here must know the answer to this. I would appreciate it if someone could let me know.

Dave

[Fitts]

Those do seem odd to me, I have never known of any speaker to have a DCR greater than the rated impedance. The numbers you have would lead me to think you have 16 ohm units. In the long run, if they sound good and the like parts have like readings, you probably don't have anything wrong.

Have you checked your meter to be sure it is reading accurately. I have one digital ohm meter that new from the box added about 4 ohms of resistance to all readings. Just some thoughts.

[marcuswilson]

The DC resistance of a voice coil is only an indication of impedance. The more efficient a speaker, the lower the DC coil resistance. Your readings, if accurate, indicate 16 ohm coils for sure. Do check your meter as Dave Fitts suggests. Most multimeters are very inaccurate below 100 ohms. Try measuring a known resistor to check.

[selmerdave]

Marcus and Dave,

Thanks for the replies. I have checked my meter for accuracy and it seems to be right. I guess this would point to replacement voice coils in my drivers, or did the 604E ever use the 16 ohm (I know the literature says 8-16 ohm)? They came from a guy that had 7 other pairs, mostly 604E's although a couple of B's and C's. I don't think these drivers were a matched pair, they were just two of his bunch, but maybe they were all redone at some point. Anyway, I won't lose too much sleep over it as they do sound nice. Thanks for the responses.

Dave

[AL-TEC]

Most of the Altec 604-E coaxes were nominally 16 ohm units. Altec just started stating in the specs in the late 60's, for 604E's, that they were "8 to 16 ohms". This is when the trend was going from tube amps with impedance taps (4,8,16 ohms), to the solid-state amps that were direct output types that were usually rated at with a nominal 8 ohm load.
I measured my "pristine" Altec 605A green 16 ohm rated models just now, and the HF driver measured about 9 ohms static resistance, and the woofer measured about 11 ohms static resistance. These I would call with their 16 ohm rated cross-overs ......."16 ohm speakers".............

just like your "nominally" 16 ohm 604E model.


AL-TEC.........

[selmerdave]

Thanks AL-TEC, that clears it up for me. I guess the impedance is quite similar for 604E's and 605's, mine measure 9.2 and 10 ohms respectively. Many thanks again.

Dave