2. amps-preamps
  3. 154746-139155

Is Parasound on to something? Or, How important is crossover management in preamps?

How important is crossover management in mid-fi receiver?

I auditioned Parasound separates yesterday — P6 and A23+ and the dealer emphasized how useful it would be to be able to control the crossover *both* for the subwoofer (I have a Rel 328) and the bookshelves (TBD, but I'm looking at Dynaudios and Salk WOW1's). Not many preamps have this, and I'm wondering how important it is. I'm also quite interested in PS Audio's separates (Stellar Gaincell + S300) but they do not have these, nor do they have tone controls.

So how valuable is Parasound's controls? What is the significance (positive or negative) control over the crossover — especially of the *main* speakers themselves? The positive, I read, is that it (a) allows mains to do a more precise job by relieving them of the burden of the bottom end, and (b) it increase the efficacy of the power amp in driving the mains. Is there a negative? Is there something "improper" about limiting the demands on mains, especially given their designed frequency range?

As you can see, the answer to this question helps determine whether Parasound has a major value-adding feature in these crossover controls.

Obviously, at the end of the day, auditioning pre's and poweramps (or integrateds) is crucial, as is match to speakers, etc. But if this feature is very important for fitting sub and mains together — and fitting speakers to room environments — then it will help me weigh the Parasound or any other preamp with this feature.

P.S. To those who keep seeing my newbie questions, I hope they're not irksome. I'm posting so often because I'm researching purchases for a whole system, of some cost, and so I'm really digging into these questions about all aspects. And I'm having a blast.
hilde45

Showing 3 responses by almarg

almarg's avatar
almarg
9,670 posts
 
If I didn’t prefer the Parasound, though, I supposed I could get an external crossover and have that feature with a different preamp — perhaps with more precision, even? That would allow me to get the preamp I like best *and* having the control a crossover gives.

If I have this wrong, or if adding a crossover is a complicated affair, please set me straight. This solution could be the one that splits the difference.


That’s certainly possible, of course. But the initial complication would be choosing an external crossover that would have minimal sonic side-effects while costing an amount that is reasonable in relation to the costs of the other components.

Some pro-oriented active crossovers can be had for less than $200, while other pro-oriented as well as audiophile-oriented models can cost many thousands. (The pro-oriented ones, btw, often provide only XLR and/or 1/4 inch connectors, rather than RCA connectors). I can’t comment on where within that wide price spectrum the sweet spot might be for your purposes.

Another possibility would be a passive crossover, perhaps constructed by yourself, consisting simply of a capacitor for each channel, an enclosure, and appropriate connectors. The value of the capacitor (i.e., the number of uF, or microFarads) would be chosen to provide the desired crossover frequency based on the input impedance of the particular amp that is being used. The main upside of that approach is of course low cost. The downsides include slow rolloff (6 db/octave), and the difficulty of determining what crossover frequency is optimal for the particular speaker and hence what the value of the capacitor should be.

Regards,
-- Al

almarg's avatar
almarg
9,670 posts
 
@cal3713 Thank you kindly for the nice words.  I always value and enjoy your posts as well.

@hilde45, Excellent answer by Mr. Salk, as Doug had prognosticated.  I would add that even if a woofer does not bottom out, as it approaches that condition the sonics of a speaker are likely to be adversely affected in various ways.  And that figures to be especially true in the case of the WOW1, given that its woofer is undoubtedly handling just about the entire midrange, as well as the bass.  (The woofer it uses has a recommended frequency range of 60 Hz to 3500 Hz; the tweeter it uses has a recommended frequency range of 2.5 kHz to 25 kHz).  

Also, if you were to go with a different speaker now or in the future, as I mentioned earlier the P6 would provide you with the flexibility of being able to conveniently remove its high pass filter from the signal path, via the switch it provides on its rear panel for that purpose.  

Good luck.  Regards,
--Al

almarg's avatar
almarg
9,670 posts
 
... I'm looking at Dynaudios and Salk WOW1's

Considering the diminutive size of the WOW1 (7 x 9 x 10.75 inches, including a 4.5 inch woofer) my guess is that **in this specific case** the sonic benefits of keeping the deep bass out of the speaker are likely to outweigh whatever sonic downsides may result from introduction of the P6's crossover circuitry into the signal path. And if that proves not to be the case the P6's crossover circuitry can of course be switched out of the signal path.

Without knowing the specific Dynaudio model(s) you may be considering I wouldn't want to speculate on the net result of that tradeoff .

Regarding the dilemma cited in one of your recent posts, every design approach has tradeoffs associated with it. And the net result of those tradeoffs usually depends on how well the specific design is implemented, and on how it synergizes with the rest of the system. So I would not consider the rationale of either company (PS Audio or Parasound) to be specious. And in choosing between the two products I would take into account the specifics of the application as much as possible.

Good luck. Regards,
-- Al
 
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