Is bi amping worth it ?

Quote from Greg Timbers past engineer for JBL see below:

''You use the processors from DEQX, can you explain why?

I have been playing around with electronic crossovers at home for many years. There is a detail and clarity to electronic systems that passive has trouble matching. However, there is often a musicality to the passive stuff that is difficult to achieve with a purely electronic chain. I was stuck with the compromise between a very nice analog active crossover system vs. digital stuff.  The analog sounds very nice, and in my case better than any digital solution I had tried. The digital has the ability to do room EQ for free and fix a lot of problems.  I could get great response and tonal balance, but I was always lacking in the musicality and "out of the box" presentation. 

I had read about the DEQX and decided to try them. My system is very complicated being a fully active 4-way system so implementing the DEQX solution took a while. I was intrigued by the ability of the DEQX to eliminate group delay at the crossover points. This is something that can't be done in analog and although people claim to have time aligned systems; they still have group delay in the crossover range. Even first order crossovers can't solve this problem since the individual drivers do not have the bandwidth above and below the crossover points to not contribute to the "acoustic slopes". 

By using FIR filters, amplitude and phase can be manipulated independently so this constraint can be overcome. The hardware in the DEQX is very well implemented indeed, but it is no match for the esoteric discrete analog stuff. Still, the complete amplitude and time correction easily overcomes this handicap and has given me the best of both worlds. I now have all of the detail, dynamics, smoothness and special attributes I have been searching for with the ability to do room correction and frequency shaping as I wish.  It is a win-win for me.''

See full interview here

Mike

@russbutton Nice explanation, thank you. So, why is a Krell amp better suited to run a 3 or 4 way system with passive crossover? I believe that my Parasound amps do a very fine job of powering the AR9's. They are 4 way with 2x12 wooferrs each on the low side, the top is made up of a low midrange driver (8 inch, I think), upper midrange driver and a tweeter. There are 3 toggle switches in each cabinet, allowing control of bass, midrange and treble. You can set at zero, minus 3db or minus 6db to adjust mostly for room acoustics, I would imagine. I currently have them all at zero.

I am not in any way questioning your answers, just trying to understand why. BTW, good job explaining to someone with very limited knowledge of the components. I do understand the basics but most of the EE stuff is well over my head. Thanks again.

@billpete I believe that John Curl is the chief designer for Parasound, so their amps are going to be very good.  I don't know that Krell is better than Parasound.  I just know that they are more expensive.  I like to say that today's $10,000 wonder is tomorrow's $5500 white elephant.  

Chances are if you were to sub in a Krell amp into your system, that it would sound a bit different.  Depending upon your opinion, it might be better or not.  It's my expectation that the difference between your Parasound and a Krell would not be huge.  But if you were to compare either of them to an amp from someone like Adcom or Cambridge Audio, that you would hear greater differences.   I think that Parasound is closer to Krell than it is to Adcom.

But were you to remove your passive crossover altogether and replace it with an active crossover, a pile of Adcom amps and level match them properly, you'd be surprised at how good it would sound.  

In practice with home systems, it is mostly in DIY builds that you see people using active crossovers and a pile of lower cost amps.  You really can't sell a commercial loudspeaker and then tell the customer they have to buy an active crossover, a pile of low cost amps and be sure to level match them when they get home.

Pro audio systems have been doing active crossovers for decades.

@ditusa --

+1

@russbutton --

+1

@russbutton wrote:

The do very different things.  An equalizer alters the system response.  Typically the operate on ten bands across the audio spectrum.  

A crossover, either passive or active, is designed to separate out the signals being sent to the loudspeaker drivers.  High frequencies for the tweeter and low frequencies for the bass driver.  If you have a 3-way system, then the crossover has the added function of allowing only an intended band of signals for the mid-range driver.

But as you know an active, electronic crossover/DSP also has an equalizer function in the amplitude domain integral to its design "raison d’être." Apart from dividing the signal sent from the preamp and passing it on to the power amps with chosen filter slopes, types, cut-off frequencies, delay etc., each driver band also has its overall gain setting and a number of PEQ’s (i.e.: Parametric EQ):

In my own Xilica DSP there are 8 such PEQ’s for each driver band (3 of them per channel for a 3-way system), and that means the opportunity to choose up to 8 specific frequencies (in single Hz increments) within each of these bands that can be positively or negatively gained in 0.25dB steps from a chosen Q-factor (i.e.: the sloping width around each of these frequencies). That means 3x8 PEQ’s + the overall gain structure for the 3 individual driver bands.  

In fact there’s also an "equalizer" function in the time domain in the shape of delay settings; IIR filters that applies a specific delay to the whole of each frequency band, and linear phase FIR filters that have some 65,000 delay points over the frequency spectrum (obviously not done manually).

Which is to say: functionally an active crossover is also an equalizer, whereas an equalizer is only that. What’s more and not least: with an active crossover the equalization is done at the heart of the crossover itself, and not as an additional hardware component. What an active crossover lacks in the number of equalizer bands it can make up for getting the overall gain structure of each driver band right from the outset, which is the easier part. The rest with PEQ’s is fine tuning, but also the hairier aspect that can really lift the overall performance. 

@russbutton John Curl designed a number of amps and preamps for Parasound. Cost dictated the parts that would be used to keep most of them at competitive prices. I know he designed the PLD preamps and they are silver wired, dual mono design but do so with a single power supply, not sure how that works but it is a nice preamp. I have a PLD2000 and used it for over 20 years until it began to have problems. Nothing major, the balance pot failed and I can't find a dual mono balance pot anywhere. I finally have found someone who can fix it with or without the pot. 

John Curl also designed the HCA amps, they may also be silver wired, I can't remember. I do remember reading from JC himself saying that if he were to do them again, he would use copper at least for the ic's. He also has many suggestions to make these amps and preamps better with some mods. Again, they were done on a budget and supposedly some relatively simple mods can make them considerably better.........so it is said. JC also designed the JC designated mono blocks and other later Parasound gear. I think the JC1's are said to be some of his finest work. They are not cheap.

I believe Nelson Pass is the designer of the Adcom amps and they have been highly regarded over the years as good bang for the buck pieces that don't break the bank. It seem to me that Pass and Curl have opposite ideas on how to build quality. I think NP also did  the old Threshold amps and maybe others and on to his own Pass Labs. Seems to me that Pass is a keep it simple approach and I like that approach, I've just never had it. Curl designed pieces seem very complicated. I have read that some of the mods, even the ones that Curl himself advocated, involved removing a fair amount of parts. Not sure what that means.

I give up, Agon is running terribly for me today.