Dan Brandesky wrote on Thu, 27 January 2011 19:08 |
However, the 1828T driver still has a bit more lower midrange, whereas the 1828C has a bit more upper mids. Which brings me to my next thought: would the added length of the 1828T's body modify the acoustic characteristics of the horn in the way I described? The 1828T is maybe 2 inches longer than the 1828C, which means the rear driver exit is 2 inches or so further from the horn than the 1828C's rear exit is. Am I grasping at straws again, or could I be on to something?
The only thing I haven't done yet is blasted the horn out with some compressed air, because I don't have access to an air pump at the moment. Either way, I don't think that's the issue.
Thanks again, Dan
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The 1828T has a transformer in it, even at the 30 watt setting it is 166 ohms.
The transformer will make it sound different than the 1828C, which has no transformer and is 8 ohms. A rolled off upper response would be expected.
If you are using series capacitors, a 5 microfarad capacitor on the T model would be about equal to a 100 microfarad capacitor on the C. The same value capacitor used on each will allow the T model to play much lower in frequency, so it would have more LF output.
You must bypass the transformer to make any valid comparisons between the two drivers.
If the actual driver housing is different in size and shape, the response will be different between the two drivers.
If the "T" driver is 2 inches different between the front and rear threaded exits, the internal size is not the same.
The spec sheet does not show a different depth for the drivers, so my guess is the actual compression chambers are the same for both, and the "T" simply has a larger housing to fit the transformer.
The spec sheet does not mention differences in frequency response, your differences are probably mostly due to the transformer.
That said, differences of several dB between old drivers is quite common, you have different vintage diaphragms, so I'd expect they won't have the same response even if you bypass the transformer, and have perfectly aligned both diaphragms.