Help me understand how to optimize bass on the Zu Definition Mk IV

@temicxoch As a SET amp the 300SE is neither balanced nor bridged, so you're fine in that respect.

Good luck.  Regards,

-- Al
 

Temixoch, good luck. There's no doubt that 4x 10" woofers firing 6" into a wall would produce a very pressurised bass, whereas 1x 12" firing down into the floor is a whole different concept.

My Revopods raise the Def4s 1.5" off the floor (I also situate the Zus on Panzerholz pieces).

FWIW, Jaco and Geddy sound pretty good here.

My Def4s are 6" from the back wall, and the floor is wood glued to reinforced concrete. Sean delivered the speakers, dialed in the bass amps, and the output curve is flat (see the owner's manual):

Volume=9
Low pass=45
PEQ Gain DB=3.0
PEQ frequency=35
Phase in degrees=0
Gap=1-1/4"

Bass is tighter and more cohesive than either the 1.5s or 2s. You can always call Sean for suggestions.

GSM, I've just tried yr settings and really quite like the sound.

For the OP,

Are your Def 4s new or did you buy them used and they're simply new to you? There's a reason I'm asking. What are your room dimensions? Which 300B tube are you using in your SE amps?

I started with Def 1.5 back in early 2005. Then Def II, then (and still) Def 4. All three have been placed in exactly the same location. With the 4x10" back firing arrangement, I did have speakers placed close to the wall behind, but no corner loading. Under normal circumstances, the Def 4 12" sub should easily outperform the older 4x10" array, in bass depth, quality and amplitude. The old plate amp on the 4x10" wasn't as powerful as the sub amp in the Def 4. However, with 6" clearance to the back wall and 2' to the side, with the backfiring array you certainly had corner loading with the Def 1.5 that has gotten you accustomed to exaggerated bass. You might just have to wean yourself off some of that, because you are not going to get the same amplitude of corner loading from the downfiring sub in Def 4. Particularly with your 300B SET amps. You'd have corner reinforcement of rising THD bass.

On the other hand, Def 4 gives you control that laughs at the simple level knob on Def 1.5 / 2. So alot can be accomplished by getting the controls combination settings optimized. But first I need the answer to the questions whether your Def4 are new from Zu or used. Then I'll have more to suggest.

Phil