to tame the bass bloat in my Harbeths when driven by tube ampsWhat amplifier and what Harbeth? This might be solved in a simpler fashion!
Showing 3 responses by atmasphere
There is no problem with my Hegel H590 or Class D Audio SDS 470C amps, just my ARC Ref 150se. So... it's not the room... its the amp.You might know that I'm a tube amp manufacturer (that also holds a patent in class D amps as well). Take it from me on this bit (since the solid state amp is fine, we'll assume that a DBA isn't needed): speaker cables can affect tube amps a lot more than they affect solid state! So I have two recommendations: try several different cables and keep the cables as short as you can: under 3 feet if possible, and make sure the connections are tight. I would also try different taps on the output transformers of the amp as that affects things too- sometimes counter to what you might expect.
which is primarily the result of room issues and secondarily related to the more limited control by tube ampsWhen you have bass problems in a room, the number one reason is standing waves. These cannot be controlled by DSP or room treatment.
The problem is that the room has a dimension and bass waves will reinforce at certain frequencies and cancel in others. So unless your bass traps are actively able to move about the room as the bass notes change they will have little effect. DSP doesn’t work because it tries to make your amplifier put out more power at one frequency and less at another. But when you are dealing with a standing wave you might be able to kill a bit of bass bloat at one frequency but you can put as much power as you want into the bass nulls and the waveforms will still cancel. So its only slightly more effect than bass traps.
If you really want to deal with this problem, the elegant way to do it is to use a distributed bass array which can break up standing waves, resulting in evenly distributed bass throughout the room. Do do this, you take advantage of the simple fact that below about 80Hz in all but the largest rooms, the ear cannot detect where the bass is coming from so you can run the bass in mono. But it is important that the subs do not reproduce anything above 80Hz; in this way they will not attract attention to themselves. You’ll need at least four subs to do this right. They need to be asymmetrically placed in the room and therefore do not have to be aligned with your Harbeths. One sub system called the Swarm (www.audiokinesis.com) is also the most well-known sub designed for this purpose. To minimize their size they are designed go directly against the wall and take advantage of the room boundary effect, to go flat to 20Hz.
You might want to check into this; if your tube is a typical push-pull amp with some power to drive Harbeths, the bass bloat likely has nothing to do with the amp.