Pass Labs XVR1 crossover

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#41
hello to all,

I am new a member to the site and love it, I am on the process of designing some loudspeakers 3 way and may be 4 way.

My plan was to use an active crossover for a base to start designing specific passives for the product.

As I understand or can you clarify is there only one model you have designed, which model will suit my needs

i have found a few threads out there on model numbers
any guidance is great

looking forward to hearing from you
 
#44
Pass Labs only has the one crossover available. The XVR1. You can get the manual from their download page, under "customer support" at the passlabs site.

Mr. Pass's First Watt company has two crossover products, the B5 and B4. You can get the manuals for those from the Firstwatt site.

Those manuals won't tell you exactly how to build a crossover, but they will give you enough information about the system design to decide what you want to do.

For some details on filter circuits that you might use, you could look at Grey Rollins' articles at Enjoythemusic.com. Here's a link to the second one: The Xenover - Part II Article And Design By Grey Rollins

Good luck!
 
#46
I, too, am extremely interested in a DIY AXO.

The only one I found that seems to have gotten some legs was the MOX series. It wasn't clear to me whether this was at odds with NP. If so, I would not build it.

I hope NP will release an AXO design at some point sooner than later. I want to respect his wishes on IP and his efforts. Is there a time line on the AXO DIY NP design?
 
#47
years ago I remember a mention of something called a "High Low Pass" but, I never actually saw an article or right-up?
There is someone on this Forum who created a circuit that is likely similar to the B4-5 units. Using B1-Like buffers. I can't recall the name at this moment?
:Pawprint:
 
#51
cyclotronguy said:
This is not the intended use for the XVR1 but it certainly is possible. Having 39 frequency steps per pole, one to four poles per filter, and variable "Q" for each pair of poles is a bit overkill for subwoofers.

You can sum the outputs and drive a single subwoofer.... or not sum the outputs and drive dual voice coils on a single subwoofer.

Cyclotronguy
Click to expand...

Nelson Pass said:
You forgot the 3 frequency multipliers. 😉

Actually though, I find that degree of adjustability most
useful for subwoofers, being that they usually need some
equalization also.

I occasionally put 1 or 2 poles down at 22 Hz or so to really
flatten out the response and then additional poles to get
rid of the woofer above its usable frequency. It may only
result in two octaves of response, but it's flat.
Click to expand...

I have B&W 802 Matrix speakers with North Creek external crossovers (which I like) and I want to add a pair of subs to the mix (JL Audio F112's for example). Any reason I couldn't use the XVR1 to drive stereo subwoofers and my main amp (to the North Creeks -> 802s)? I've seen the Bryston 10B Sub used in this application but I want something more transparent and flexible.

Any recommendations for crossover points, slopes, etc. bearing in mind that the 802's are ported and the subs will be sealed?
 
#54
You should search for "mox" probably? Don't remember but, Mox is a descrete JFET opamp and an EQ was built ussing the XVR1 philosophy and the "MOX" modules I think...
I'm still watching the PassDiy site for the "Hi-Lo Pass"?
 
#55
by page 30 about
ftp://184-tar-2.acn.waw.pl/pub/Pass/XVR1MAN1.PDF
there is show the simplified schematic from this very effortful manufactured electronic active crossover.
Follow questions rises up:
1) What is the advantage by use of the Sallen-Key topology?
Until now I think, the MFB (multible feedback) topology provides the lowest values for THD
Design and Dimensioning of Active Filters
2) By most of the me known Sallen-Key topologies there is only one half of the frequency determination parts variable. Usually the resistors (easy in the low pass, more difficult but also possible by the high pass because of the additional necessary acoustic synchronism resistor network for the potentiometer to compensate the acoustical gang error, thus in most cases only switchable capacities are in use).
What are the main advantages, if there is variable both resistors and capacitors like in this model ? - this I don't understand clearly, because there is additional a "Q" pot for the characteristic, i. e. CH-BU-BE (Chebyshev-Butterworth/Linkwitz-Riley-Bessel).
Thank you very much for an explanation or a link where I can read this details.
 
Last edited:
#59
B-5 verses XVR-1

Bi-amping crossover question.

I have a pair of Golden Tube Audio SE-40 Amps, a tube preamp which is an updated version of the Marantz 7 without the tone controls, and Mangepan 1.6QR speakers. Also a Volksamp 30 collecting dust at the moment.

I'm looking to bi-amp the 2 tube amps and need to acquire an active crossover.

Question:
Other than build quality and power supply quality, is there a recognizeable difference sonically between the First Watt B5 verses the Pass Labs XVR-1?

I can afford either one, but would rather put the coin to other components if the B-5 is diminishing rates of return difference from the XRV-1.

Also looking to tinker with open baffle speakers at some point too.

Thank you!
 
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