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Using SS to augment < 100Hz?

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bigwill

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Joined 2004
Has anyone ever tried using a low distortion SS buffer coupled to the speaker somehow as well as the secondary of an output transformer to augment the deep bass and take away some of the strain from the OPT?

It would probably be quite tricky but it sounds like a neat idea.
 
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bigwill

Member
Joined 2004
One idea I had would be to take a sample of the deep bass from the drive signal going to the output grids and let it "sneak past" the OPT and drive the SS buffer somehow. Not sure how you would couple it, and you'd have to use global NFB (hopefully not much) to make sure the frequency response was flat. One could use a chipamp for simplicity...
 
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theoldtrout

Member
Joined 2008
Many years ago I was faced with a similar problem but cheated and split the signal at the valve pre amp output using a LP filter and fed the bass to a home made transistor power amp and the above 100Hz signal to the valve power amp. I suppose it was a sort of el cheapo active crossover - sounded OK.

Never really thought about bypassing the o/p transformer before. I'm certain that something could be designed, need to keep the phase correct though. Interesting idea.
 
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Eli Duttman

Member
Joined 2004
bigwill said:
Has anyone ever tried using a low distortion SS buffer coupled to the speaker somehow as well as the secondary of an output transformer to augment the deep bass and take away some of the strain from the OPT?

It would probably be quite tricky but it sounds like a neat idea.
Click to expand...


That's exactly what happens, when you use the speaker level I/Ps of a powered subwoofer. :D The "best" arrangement connects the SW in parallel with the main speakers and keeps the bulk of the signal out of its crossover. The main speakers play as close to full range as is possible and the controls on the SW are adusted to fill in underneath.

Another good thing about the arrangement described is the low cost of the cabling to the SW. As this is a low current situation, 16 AWG OFC "zip" cord is quite sufficient. If the run from power amp to SW is very long, use 14 AWG wire.
 
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