My experience adding subwoofers to 2 channel

The DD amps are not designed after the Acoustats other than they provide the requisite voltage to the panels. A while back Roger designed a drop in board for the Acoustat amp that used 3 x 6DJ8/6922 for a tube input. IIRC his amps also use this input, but he also designed a different output. The ESL is a single flat panel designed for wider dispersion than other panels of this type. I am not sure of the measurements but it has a small footprint. If I had to guess it is 40" tall by 18" wide. Roger does use the panels and amps in his system with an active crossover and two bass speakers.

Dear all, as stated in a post above, I’ve tried a lot of subs, and gradually gave up on it, preferring another system (main + effect speakers) instead. Why? I worked a lot with sub positioning. Getting the subs and the room to agree. The more that can be done in the analog domain the better. Next, I worked a lot with equalizing and adjusting crossover, especially with the Velodyne DD18, recording in REW, looking at the output, and so on. Eventually, I got bored. +1 to mijostyn, above - "bass is about feeling".

Why did I get bored? Because, with a very good set of tube amps driving big horn speakers, the sub importance declined. I decided that I was willing to live with somewhat diminished below 35 hz frequency, since the rewards in other respects (purity and relaxed natural quality of sound) was greater. To my ears. Listening over several years, in my 20 x 27 feet living / listening room.
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Why did I say farewell to subs? Was it timing? I don’t think so. I found that the subs usually sounded best when time-aligned, roughly, by positioning them relative to the main speakers. I often ended up with subs and main speakers in a half circle, facing the listening position, or with the subs a bit more forward, to keep up with the front speakers. Was it poor crossover integration? No, I found the best crossover point and slope, and even then, I wasn’t fully satisfied.

Why not? It was the amps in the subs - is my hypothesis number one.

When I got the Velodyne DD18, replacing a pair of more anemic REL subs, I was so glad, I remember saying aloud: "Hello, bassist!" I clearly had more quality sound in the lowest frequencies. But over time, this changed into "Hello, solid-state". Or whatever it was, that disturbed the sound, and made it more tense, with the sub turned on. So to get the purest musical experience I often found myself turning it off. I did not like the "glare" it put into the music, which I associated with solid-state sound.

I am not sure of this hypothesis, maybe it has to do with more conventional problem factors like poor timing or x-over behavior, but I dont think so in my case. It mainly has to do with poor sub amping, compared to the amps driving the main speakers. Especially obvious if you are using top notch tube amps to drive the main speakers, and cheap s-state to drive the sub(s).

Noble100 - re: debra / swarm system - phase changes. I have found reasons to not always follow Audiokinesis advice "mechanically" - it depends on your room and a bit on your listening tastes also. So I’ve now found that my main Dream Maker speakers - to my ears, in my room - sound better crossed a bit behind me, not in front of me like Audiokinesis advices. In other words, a more conventional speaker setup with less toe-in. This may apply to my use of the LCS effect speakers also. Not sure yet. Based on Audiokinesis philosophy the idea is to spread the reverberant sound around and "decorrelate" it as much as possible. Based on advice from James Romeyn at Audiokinesis, I run the effect speakers so that one channel phase (polarity) is shifted. And some other mods that I am not sure about. The great thing with the Swarm and Debra system - and the Dream Maker / LCS system I have - is that it is very much up to the user. Position the speakers right, in the room, adjust phase / polarity, and the reward will be there.

Hello o_holter,

     James Romeyn at Audio Kinesis is the guy who convinced me to give the AK Debra 4-sub DBA system a 28-day free home trial.  I started off a big skeptic but, after hearing the bass response in my room and system, I'm now probably one of their biggest proponents.  By a wide margin the best bass I've ever experienced in my room and the integration with my large Magnepan panels is absolutely seamless.
     I followed the Audio Kinesis Debra sub positioning procedure exactly and it turned out very well.  However, their advice was to sequentially reverse the polarity on a sub at a time to determine if it improves overall system bass performance.   After spending half a day setting up my DBA system I was a bit tired and wanted to listen to it.  I figured I'd get to that step when I could. But that was over 4 years ago and my subs still sound great running in-phase, so I now consider this phase reversal step to be optional.

Tim

Hi Tim
Optional - exactly. I have followed Romeyn’s advice in my own LCS setup, and 95 percent of it was extremely helpful and good. But at some point, it becomes a matter of individual room integration and also listener preference. I do use phase reversal with one of the LCS speakers, it sounds a bit better than correct phase, but I should probably test this again now that I have changed the toe-in of the main Dream Maker speakers. This is, again, an "optional" issue, to my ears. Some like it when they cross in front, some - like me - prefer a more conventional toe-in where they cross behind me. I mailed Jim Smith (author of Get better sound) about this, since in this book, crossing in front is not recommended, it harms the tonality or harmonics. But he wrote back: It is a matter of preference.