B, B2, B3 xo differances

[mopardave]

can anyone explain the differences and why there needed?  Thanks

[jjptkd]

According to Klipsch Cornwall history:

 

June 1981: "The updated B2 network, with steeper crossover slopes is phased in with no changes to the K-33-E, K-55-V and K-77-M drivers." 

 

Mar 1983: "The B-3 network and the K-52 midrange driver starts to be used in this model."

 

I'm not sure exactly what the differences are between the original B and the B-2 (other than the stated steeper slopes?) but everyone here seems to prefer and recommend the B-2. I know the B-3 was added when they changed the mid horn driver to the 1.5" type instead of the k-55v. 

[mopardave]

Cant remember what i used for mid drivers in my home brew cornwalls, but i built B ox for them.  Maybe they should have B2's.  What does the steep slope do to them or make them sound?

[mopardave]

Still curious to what the steeper slope does to the sound of the speaker?    I need to check, but i think i have the k57 mid drivers that are currently stored at my fathers home.

[Schu]

Less over lap in the driver handoff.

[jjptkd]

Found this last night about the B-2:

 

CROSSOVER NETWORK CHANGED:   CORNWALL

Vol. 20, No. 1

June 1, 1981

 

NEW DEVELOPMENT

The product-evaulation program at KLIPSCH and Associates constitutes the lion's share of our Research and Development effort. We are now gratified to add another entry to the long list of performance improvements made in our product line over the years. Advances in the state-of-the-art of sound reproduction frequently result from innovation of new techniques of acoustic measurement, the aim being to utilize quantitative tests which closely corroborate the psychological sensations of the listener. Thus new measurement techniques or bolstered power and convenience of data-conversion bring excitement to the work of design, but always with the sobering constraint that new test results carry import only to the degree to which they have psychological significance. That is, the test format must be such that the genuinely most significant acoustic parameters receive the greatest emphasis during

design. The latest in a long series of "technical papers" from KLIPSCH Engineering explains the operation of our unique "Anechoic Chamber With Optional Boundaries" (AES Preprint 1979) which facilitates deeper scrutiny of loudspeaker response characteristics.

 

The KLIPSCH CORNWALL has taken yet another step in its evolution toward optimum performance.  A complete re-design of the crossover network has made possible a significant improvement which we now happily share with the audio public. Briefly, the new design entails the following:

 

1) Constriction of the electrical signals received by each driver to the spectral band over which the driver displays optimum characteristics is a salient feature of the design.

 

A)      Boosted woofer output is obtained in the 400 Hz to 600 Hz region.  Combined  with a more rapid transition to an attenuating characteristic at frequencies above cut-off.

 

       Substantially decreased low-frequency  energy is applied to the midrange driver.  Though tremendous improvements are not possible in this regard, intermodulation distortion is somewhat reduced and the possibility of squawker failure is made even more remote.

 

C)       Dramatic improvement in the stop-band attenuation is provided by the highpass filter associated with the K-77MTweeter. Overall, this means that more energy can be derived from the tweeter above 6 kHz because of reduced current-flow into the tweeter in the mid-band.

 

2) Studies of the cross-correlation of woofer and squawker output waveforms have precipitated a substantial increase in coherence near the crossover frequency.

 

A)      The attenuation characteristics of the woofer (low-pass) and squawker (high-pass) filters are associated with a particular set of phase characteristics; the two are mutually dependent and cannot in general be manipulated individually. The roll-off rate of the woofer filter and the spectral location of the cut-off point of the squawker filter govern the relative phase relationship of their outputs in the crossover band. Only a special set of circumstances will allow optimization of filter phase characteristics without an associated deleterious effect on the amplitude attributes of the filters' transfer functions.

       Driver polarity does not affect the amplitude response of the driver in question, but does in fact greatly affect the steady-state response of the system considered as a whole. In this case, the mechanical location of the sources, the phase characteristics of the electrical filters, and the relative polarity of the drivers are manipulated in a harmonious manner to render the crossover-band response smooth and non-anomalous.

 

Designated the Type B-2 Crossover, this new network is aimed at genuine improvements to the overall characteristics of the CORNWALL Loudspeaker System. The effective date of this change is approximately June I, 1981. We plan to make the transition in smooth manner, hence the early notice.  As always, we will maintain stock of Type Networks and adequate repair facilities for CORNWALL  owners.  Since in general no change in drivers.or cabinet is associated with the network, an update from the Type B to the Type B-2 will be a relatively simple matter.   Owners of older CORNWALLS are  encouraged to incorporate up-to-date drive components (K-33E, K-55V with nested phasin plug, and K-77M) to maximize the benefits derived from use of the B-2 Crossover. An update kit (Type B to Type B-2) will soon be made available through the KLIPSCH dealer network.

 

DAN BYNUM

ENGINEER

 

 

[mopardave]

Great info guys.   Thanks for that.

[geoff.]

Hello Dave, I was fortunate enough to land a pair of 1984 CW 1’s as my FIRST pair of Cornwalls. They came with the B-3 and K-57/601. They also had the square magnet K-33E woofer. I sold my FIRST pair of Forte ii ‘s shortly afterward.

 

They were black so when a pair of walnut ‘79 Cornwalls became available I grabbed them. They came with the B and K-55/600 combo, with a square magnet K-33B woofer.

 

I had no idea what to expect sound-wise.

 

The difference in sound to me was so different that I sold the ‘79 CW’s shortly after. I would say “day and night”, Cornwall-wise. Lol.

 

Not to confuse things TOO much, but by sheer luck I landed a pair of walnut Cornwall 2’s before letting the ‘79’s go.

 

I had a chance to compare all three. 

 

The last run of the Cornwall 1’s (1984-1985) with the B-3 crossover give the Cornwall 2 a real run for the money.

 

Obviously the CW2 goes higher, but the highs are not “missing” in the CW1.

 

Under different circumstances (less room or money) I would be hard pressed to decide which to keep.

 

The B-3 lets you enjoy the music at more spirited levels than the earlier iterations.

 

[mopardave]

what components are in the your CW2?    

[geoff.]

The Cornwall 2 comes with K-79, K-57/601, K-34E (identical sonically to the K-33E, just gasketed different from what I have read here) and the CW2 crossover.

 

The Cornwall 2 crossover looks to be a step down in quality compared to the earlier B versions. The picture below is what came in my ‘86 CW2’s.

 

The Crites website shows pictures of the various XO’s, Bob’s version of the CW2 crossover is what wound up in my pair.

[mopardave]

sounds to me I should of built the B3 xo for these instead of the B.    Lately was thinking up grade with new caps to a B2, but now it seems B3 may be what it needs.

[geoff.]

If you have the K-57 drivers with horns stored away somewhere the B-3 would be the way to go.

 

But if you are using the K-55 you need the B or B-2.

 

Once again, from what I have read here, the K-57 is about 3 db different from the K-55.

 

I “thought” it was louder, but not sure.

[mopardave]

Pretty sure K57, but its been 14 or 15yrs since I looked inside.   I think metal horns as well.   I'll pull the backs off next time I get up there.    I'm now thinking I can pull the home built B's from the CW's and up grade them with new caps and use them in my Super Heresy project.   Then I could just order new B3"s from Crites for the CW's. Thanks for all that info, it helps getting all my ducks in a row.     

[geoff.]

The Cornwall 1’s are a real mixed bag of goodies.

 

They are like the “Bits And Bites“ of speakers... “every handful is a whole new ballgame” (anyone else remember Andy Griffith in that commercial?).

 

 

[mopardave]

Yep, sure enough, i had B xo's with k57K mids and k77m tweets.    I will be getting some Crites B3's for these as well as some tweed grill material to replace the old black covering i used and never really cared for.   Thanks