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Help wanted: Bass!

I’m in need of augmenting the bass in my system. I’m the old school type and would rather NOT go the sub route.

My system and environment:
• Pre:   Conrad Johnson Premier 16LS
• Pwr:   Conrad Johnson Premier 12 Mono Blocks
• Pwr Condtnr: Shunyata Hydra
• Speakers: Tannoy Kensingtons
• Cabeling: Stealth PGS IC’s, Vandenhull Bi-wire Speaker wiring
• Sources: Conrad Johnson DV-2B CD Player, SOTA Star w/SME arm w/Grado cart, Magnum Dynalab Tube Tun 
• Music:   Classic Rock, Easy listening, Female Jazz singers, Classical
• Room:   Big (25 X 30) w/cathedral ceiling. Harwood floors/ceiling and big glass windows. Rugs and furniture

Came across the Emerald Physics Bass Manager claims to add 1/2 octave of bass to any speaker. IYO, could that be a solution? Are there similar helpers like this out there? Not much in the budget (about $500) for a near-term purchase. Could double that for a longer-term.

Again, not wanting to go the sub route unless I have too. Can’t do room treatments or alter room configuration (it’s our living room) either.

Any thoughts/suggestions will be greatly appreciated – thank you!

rbschauman
georgehifi's avatar
georgehifi
10,312 posts
 
rbschauman

Do get the knowledge to try to change the speaker output impedance taps yourself first, before spending any money.
You have 4 different ones to try and you maybe surprised as the ported 10" Kensingtons have usable output down to 20hz (-10db). See frequency response, 1st graph near the bottom, the red trace is the port bass output, the green trace is the drivers output, if you visualize the two added together, you see you do have quite good LF bass.  

http://www.hi-fiworld.co.uk/index.php/loudspeakers/65-reviews/745-tannoy-kensington-gr.html?showall=1

Cheers George
almarg's avatar
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almarg
9,670 posts
 
Bob_Reynolds 7-17-2016 5:16pm EDT
If your preamp has a 2nd pair of outputs, then use those for the sub. Otherwise, you can use a Y-connector to split the preamp output between the sub and main amps. The problem with using a y-connector is the effective impedance the preamp will see, which can be a real concern for tube preamps. The impedance of line level connections on subs are typically in the 10K ohm to 20K ohm range.

I would add to Bob’s characteristically excellent comments that in the majority of cases where preamps provide two outputs for each channel both of those outputs are driven by the same output stage circuitry, and are simply jumpered together just inside the rear panel. Which means that in those cases the impedance compatibility concern would occur no differently than if the preamp provided just one output for each channel and a splitter is used.

In this case it appears that your 16LS preamp does provide two sets of output jacks, and according to Stereophile’s measurements its output impedance rises to about 1800 ohms at 20 Hz, while being much lower at mid-range and treble frequencies. Assuming, as is likely, that both output jacks for each channel are driven from the same output stage, the output stage would see a load impedance corresponding to the parallel combination of the sub’s input impedance and the 98K input impedance of your amp. Which will result in an overall load impedance that is less than the individual input impedances of both the sub and the amp.

Therefore if you choose to connect the outputs of the preamp to a sub (or to two subs), as opposed to connecting the outputs of the power amps to sub(s) that can accept speaker level inputs, I would not choose a sub having an input impedance of less than about 20K. 20K in parallel with 98K results in an overall load impedance of (20 x 98)/(20 + 98) = 16.6K, which is already slightly in violation of the 10x rule of thumb guideline for assuring impedance compatibility, relative to the preamp’s 1800 ohm output impedance at 20 Hz.

Good luck. Regards,
-- Al


rbschauman OP
137 posts
 
More excellent posts with advice to a technical level - love it!

Greatly appreciated gentlemen. I certainly feel that I've taken a big leap today in acquiring the needed know how on how to confront and resolve this issue. 

Kindest regards,
Randy
 
erik_squires
16,051 posts
 
Honestly, while I love well-tuned subs, in your case would avoid subs at all cost, because you don't want to do any room treatment.  The deeper in the rooms response you go the more chances you'll have to make the room ring like a bell, and then subs get a bad rep for not being as detailed, not being as good, whatever, compared to the mains.

Your single best bet, after the amp taps, is to measure, and EQ appropriately.

If you said you had flexibility of sub woofer placement, were willing to consider some soffit traps, and began with an EQ in the picture, then subwoofers would be a direction I'd suggest.  Otherwise go ahead, I'll just show up with popcorn.... :)

Best,

Erik
georgehifi's avatar
georgehifi
10,312 posts
 
I just read that the ports also on the Kensingtons are side firing,, make sure they have room to do their thing, and again try the different output taps on the CJ 12's this is where the bass drive, control and bloom will be affected the most. 

Cheers George
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