In Reply to: RE: Sansui SP-3005 project confusion posted by Bill Fitzmaurice on October 5, 2016 at 07:52:49:
I tried to input the same parameters into different software. The Sansui port appears to be tuned to 64Hz according to online calculators. I got around 70 using the helmholtz resonance formula, but that isn't really accurate. The big peak in the bass is present on every simulation I try.
When I measured the parameters of the driver, I used the me the methods in David Weems books, and the Elliot sound website. I used a signal generator, power amplifier, 10 ohm resistor, and radio shack DMM as a volt meter and frequency counter. I used the added mass method for calculating the Vas, I blu tacked a couple capacitors to the cone and then weighed them using my ortofon tracking force digital scale. I think I followed the method properly, but it's always possible I made a mistake since it's the first time I have measured a driver in over 20 years, and I am only a hobbiest.
That said if I did it all properly, the original enclosures do look like they have a big peak in the bass region. I don't want to build speakers with this characteristic, it won't sound any good. I never heard them before taking them apart so can't comment on original sound quality.
These speakers are from 1972, so definitely in the late 60s early 70s range.
For the rebuild, the consensus is to abandon the port and slightly increase enclosure size? I sure like how the response looks better when I simulate that version.
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Follow Ups
- RE: Sansui SP-3005 project confusion - maxhifi 09:07:44 10/05/16 (3)
- RE: Sansui SP-3005 project confusion - Bill Fitzmaurice 19:43:18 10/07/16 (0)
- RE: Sansui SP-3005 project confusion - maxhifi 17:06:09 10/07/16 (0)
- RE: Sansui SP-3005 project confusion - hennfarm 15:52:15 10/07/16 (0)