elfabyanos

[quote name='jonthebass' post='453355' date='Apr 3 2009, 01:53 PM']Question bump[/quote] I wouldn't risk using an impendence that doesn't appear as an option on a valve amp. I guess guess that choosing either 4 or 8 ohms could be close enough, but if it doesn't blow up immediately you could still be shortening the life of the valves in the output transformer. Due to the lack of forgiveness in valve technology, and given the vast array of speakers available with the right impendence for your amp, I wouldn't bother with a 6 ohm cab.

[quote name='Bill Fitzmaurice' post='155968' date='Mar 12 2008, 01:52 PM']Au contraire. The best results below 40Hz are indoors, in rooms where the longest dimension is less than 14 feet, as that's where cabin gain at a rate of 12dB/octave will result in high enough SPL to hear it. To understand why google 'Equal Loudness curves'. To hear a 25Hz tone at the same level as a 100 Hz tone at 100dB the 25hz tone would have to be 120dB, and getting 120dB at 25 Hz outdoors even with a very large horn-loaded sub woofer would require about 1,000 watts. I've tested many subs outdoors, and at 25Hz and 100dB if not for the reading of the meter one would not even know there was any sound present. To the OP, faggedaboutit, you don't need response to 28 Hz and couldn't use it even if you had it. Not a bad choice, but does not perform as advertised. [url="http://billfitzmaurice.com/phpBB2/viewtopic.php?t=2362"]http://billfitzmaurice.com/phpBB2/viewtopic.php?t=2362[/url][/quote] You're absolutely bang on the money with this one. This is exactly how you get excellent sub bass response out of 20p 15" cones from Halfords in a car. A small hatch for example will have a natural bass tip up of 12db/8ve below about 90Hz, a large saloon below 75hz, a transit van below maybe 55-60 Hz, and small room maybe below 40hz. Most venues, even small ones though wouldn't get this effect until quite low, like 20hz. And outside the corner frequency is zero. Incidentally it's why I prefer closed cabs, they have a 12db/8ve roll off (whereas ported drop off much quicker below fs) so you can easily match them to room effects. I used one in my car and designed the box myself and was brilliant (IMO!). However, equal loudness curves are not to do with room effects, they represent the natural non-linear response of our ears.