Tube Friendly 2 Way Designs
Hi, I would like to build an efficient, high resolution, 2 way able to be driven by relatively low powered (8 to 24 watt 300B etc.) tube amps. Simple, passive crossover if possible. I love the sound of these amps and want to get speakers that work with their old school mojo.
I stumbled into a pair of 375 type drivers labeled "Jim Lansing by Ampex" attached to rather large metal horns labeled Ampex D-6870.
Locally, there is someone recommending a TL bass cab with alnico 2215H speaks he has for sale (are they efficent enough for this app?). I am open for input for designs that fit this general criteria and am willing to either use the 375's or something more appropiate if called for. I also have some 2235's waiting for either this, or another project in the future.
Thanks & Fire away!
Speaker Sensitivity / Impedance Targets
My target would be for the complete system including crossover & speakers to be able reach 93dB 1w/1m approx., give or take 4dB with a reasonable impedance curve. Interestingly, so called "tube watts" / or more correctly speaker driving ability, for the 300B output tube, output transformer & power supplies, is more negatively affected by large phase shifts & low (below 4 ohms) impedance dips than purely lower sensitivity output. Now what are sometimes called "flea powered tube amps", those under 4watts, need the super high sensitivity speakers to really sing...;)
Assuming a reasonably smooth impedance curve...From a 6moons article - "A good rule of thumb for watt/dB combinations is 4w/93dB where every 3dB decrease in speaker sensitivity requires double the power wattage from the amp. Hence, 8w/90dB, 16w/87B, 32w/84dB and so on.":blah:
Remember some speakers / crossovers are easier to drive than others and the whole circuit from output transformer/device to cabling to speaker network to drivers need to be synergistic....YMMV:blink:
Horn-loaded design possibility
Or you could play around with this type of design: http://audioheritage.org/vbulletin/s......sensitivity 102-103dB/watt @ 1 metre.
To me, it depends on the music.
If I'm listening to Eva Cassidy, a few watts will do. For Pink Floyds' Comfortably Numb, a few hundred watts will do.
JBL / Altec / 12" high efficiency midbass driver
Any recommendation for a vintage or modern 12" that would compare or surpass the Altec 414 in the midbass keeping in mind the 2way configuration?
"One advantage of the 12" Altec/GPA driver is a cabinet volume one-half of what a 416 or 515 15" driver require. Don't expect deep bass - that's the job for separate subwoofers, not a high-efficiency midbass driver."