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74.4.39.115
Does one type of cabinet design normally mate better with tube amps and one with ss amps? I know this is a generalization but just curious.
Follow Ups:
Thanks for all the replies.
Tomservo has covered the subject very well, so I'll just add a couple of comments.
With a ported cabinet, the designer has greater freedom to shape the low-end response in anticipation of room acoustics and/or amplifier damping factor. The response shape can be adjusted after the enclosure has been built by changing the port length (and/or diameter), something that could even be done by the end-user.
Note also that high efficiency woofers usually have parameters that will not give good bass extension in a sealed box no matter how large, so if you equate "efficiency" with "tube-friendly" your choices will be dominated by ported (or possibly horn-loaded) speakers instead of sealed boxes.
Duke
Duke,
there are a few, very few, 15s that are 95db or so that do very well in closed and even true acoustic suspension boxes. Some even come down to 50hz and blend nicely into a reasonable room. My tube amps love those types. I think they are the most articulate too. The Audio Nirvana AN12 is one a cheap Pioneer sold at PartsExpress is another.
Scott
As a General Premise: as long as the amplifier in question has the power required to drive the speaker in question, the type of amplification device (tube or transistor) or type of enclosure tuning (sealed or vented) is immaterial.
IME, tubes seem to work better with ported cabinets. Probably due to the fact that ported cabinets are usually more efficient.
Hi
Tuning for both types is done using the T&S parameters for the driver, with those one can model the particular driver and cabinet to get a predicted frequency response.
Woofers are generally made with parameters that make them suited for a vented box OR sealed box as the general requirements are different, with the vented box driver requiring a stronger motor generally.
As a rule of thumb, one can get more SPL per Watt from a vented box, more SPL for a given cone excursion limit.
In a room, one has room gain, this may add as much as 12dB per octave as you go below the lowest room mode.
As in a vented box the front and back side of the driver, which are out of phase add together below the system tuning, the response rolls off at 24 dB/octave.
In a sealed box, this self cancellation below tuning doesn’t exist, the system response rolls off governed by the cabinet air spring and this slope produces a 12 dB/oct roll off.
Thus, if one has a sealed system that has a response corner near / at the room gain corner, one has octaves of free bass extension because (in the perfect case) the room gain exactly compensates the box roll off. This is how a sealed box tuned to 60Hz can produce low bass in a car (where room gains starts about 50-60Hz).
The penalty of the sealed system is that it requires more cone excursion for a given low cutoff, distortion is directly tied to excursion.
So far as “Tubes”, all modern simulations assume the source resistance is small compared to the load, adding source impedance raises the drivers Qe and so the Qt, changing the driver parameters some.
As a load, the sealed box appears to have one large impedance peak associated with the low corner. The vented box has two peaks and a dip associated with the low corner.
It is the dip in the middle of the peaks which causes more power to be delivered, that causes the greater output in the lf corner region compared to the sealed box.
It is also that dip which makes vented boxes more susceptible to having the response change (from the model) due to changes in source resistance OR from voice coil heating.
If I were making this choice, I would consider your room size and make a large sealed box if your not making a subwoofer too and even if you were, I would make a small sealed box as it is easier to crossover because it has less acoustic phase shift associated with its lf corner.
Hope that helps some
Tom Danley
Danley Sound Labs
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