Subwoofer for classical music listener

@almarg Very informative thread. What are your thoughts about this match-up? I have a tube pre with parallel RCA line level outs going to my amp and two powered subs. The cables to the subs are 9’ each. (I have no idea what the output impedance of the preamp is.) On one of the subs, a Talon Roc 2002, the built-in Bash amp died. I have no specs on the Bash since there was no model # and the sub has been discontinued. I’ve disconnected all the wiring to the dead Bash - but, left it installed in the cabinet so there wouldn’t be any sound wave leakage. My multi-meter says that there is 3.5 ohms resistance on the sub’s 2x12" drivers. I replaced the Bash with a stand-alone Dayton Audio SA-1000 amp with 12k ohm input impedance. More spec’s here. Am I getting the best out of this amp and sub combo?

I owned REL Storm III and loved it. I tried line level and speaker level connections. I really liked what the sub could do for my system. Bought a measuring mic and learnt how to use REW. So I could measure the impact of varying  placement.

Later I bought 2 Rythmiks 12" kits and built sealed, very heavy (100 lb each), rigid boxes. For less than the REL I got better sound. Rythmiks are servo driven and also have a lot more controls for fine tuning. It was a lot better than the REL.

Eventually I went from the pre (Lamm LL2) to the subs xo and from there to the tube power amp, relieving the amp and speakers from attempting to reproduce below 80Hz. Yet another improvement. Like the article linked to earlier said. 

If you extrapolate the reasoning in that article you arrive at an active system. Later I did without the preamp altogether  abd went active. Running digital xo at the software level, adding time alignment of the sub and midbass woofer, and adding room correction is yet another leap forward. Despite this being a paradigm shift for most audiophiles thinking digital xo are detrimental. I know I'm not going back.

@Steakster, I don't think it's possible to answer your question without a lot of additional information, including the things you mentioned that cannot be determined, and also:

-- The input impedance of your power amp.
-- The length of the cables that connect the preamp and power amp.
-- Whether the outputs of the tube preamp are capacitively coupled or transformer coupled. (Or if it is one of the very few that are direct coupled, e.g., those made by Atma-Sphere).

Generally speaking, though, I would consider using a tube preamp to drive both a power amp and a pair of subs, at least one of which has an input impedance as low as 12K, to be cause for concern. Especially if the tube preamp has capacitively coupled outputs (as most tube preamps do), since the resulting output impedance most likely rises considerably in the bottom octave or two from what it is at higher frequencies. (The impedance of a capacitor increases as frequency decreases).

Something you might consider, though, would be trying to find some sort of buffer stage, that would provide a high input impedance and a low output impedance, and inserting it in the path between the preamp and the subs. Or, if the main power amp also has a low input impedance, perhaps inserting it in the path between the preamp and both destinations. Something like the Burson Audio buffer stage that was marketed some years ago, but is no longer made.

Best regards,

-- Al

   

@almarg Here’s a bit more info.
- The power amp input impedance is 50k ohms RCA, 100k ohms XLR
- The preamp outs are transformer coupled - both XLR and RCA.
- The RCA cables from the preamp to the subs are 9’.
- The XLR cables from the preamp to the power amp are 4’. Capacitance: 5.9 pF (per foot at a frequency of 10 kHz)
- The preamp output impedance is either 180 or 630 ohms.
Does this help?