muel Posted June 16, 2015 Share Posted June 16, 2015 I'm looking at B networks in late 60's Cornwalls with stock horns and drivers. (K77, K55, K33) I want to keep this pair stock or at least very close. I would like to hear from those who have experience comparing the B to the B2 network in Cornwalls. I will recap the B networks but it doesn't look like much trouble to change it to a B2 if it is worthwhile. How does the B sound compared to the B2? What does the B2 change about the B? I am also looking at getting another pair of networks from Dean but that will be for a different pair of speakers. If I could afford it I would just get 2 more pairs from Dean but I also like the idea of keeping one pair close to stock. Modifying the B network a bit doesn't bother me much though. I'm considering Jensens or Jupiters if they ever release their new model. Quote Link to comment Share on other sites More sharing options...
Schu Posted June 16, 2015 Share Posted June 16, 2015 (edited) I've never been able to do a back to back comparison between the OEM B and the B2, but I have owned both. As per a recommendation from Dean, I changed from a B to a B2 and my CW's have NEVER sounded better and I don't think I will ever go back. during my change, I failed to ask what the significance of the change (beyond layout and component) would be. Edited June 16, 2015 by Schu Quote Link to comment Share on other sites More sharing options...
Thaddeus Smith Posted June 16, 2015 Share Posted June 16, 2015 during my change, I failed to ask what the significance of the change (beyond layout and component) would be. June 5, 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 driver compliment. https://2d73e25b29782b6d6766-9c8af5cbfef16739445bc76457060528.ssl.cf2.rackcdn.com/CW_Time_Line_MK_070522_635120773187750000.pdf 1 Quote Link to comment Share on other sites More sharing options...
muel Posted June 16, 2015 Author Share Posted June 16, 2015 Thanks! That's all I found as well. I was curious about more technical details. I notice that it causes you to swap + for - on the mid and tweeter connections. I like to understand as much of the technical side as I can. The bottom line is how it sounds of course! Perhaps there is someone who had a B network and modified it to a B2? Change the 4uF to a 3 cap, add a 20uF cap and a 245uH inductor... Quote Link to comment Share on other sites More sharing options...
Thaddeus Smith Posted June 16, 2015 Share Posted June 16, 2015 good luck. i think us mods have run off any old timers with that knowledge. </sarcasm></hyperbole> Quote Link to comment Share on other sites More sharing options...
muel Posted June 17, 2015 Author Share Posted June 17, 2015 Sad... I would think some still hangout or take a look sometimes. I know the knowledge is out there and maybe already posted here on the forum but I just haven't found it yet. There were a lot of conversations about networks through the years! Considering his backlog I should probably get in line with Dean but I'm not sure what I'm going to do yet. I don't want to waste his time while I hem and haw about what I want to do. For now, I want to play with these B networks. I need to install them soon so I will be deciding quickly. Quote Link to comment Share on other sites More sharing options...
Deang Posted June 17, 2015 Share Posted June 17, 2015 (edited) Bob, If you are following this thread, would you please be so kind as to attach the Dope from Hope which explains the reasons for the change from the Type B to the Type B2. I really don't build the Type B anymore. If possible, I almost always try to move a person to the B2. Edited June 17, 2015 by Crankysoldermeister Quote Link to comment Share on other sites More sharing options...
Marvel Posted June 17, 2015 Share Posted June 17, 2015 I notice that it causes you to swap + for - on the mid and tweeter connections. I like to understand as much of the technical side as I can. A switch from a first order to a second order filter causes a 180 degree phase shift. Bruce 1 Quote Link to comment Share on other sites More sharing options...
muel Posted June 17, 2015 Author Share Posted June 17, 2015 I notice that it causes you to swap + for - on the mid and tweeter connections. I like to understand as much of the technical side as I can.A switch from a first order to a second order filter causes a 180 degree phase shift. Bruce Excellent... thanks! Quote Link to comment Share on other sites More sharing options...
muel Posted June 17, 2015 Author Share Posted June 17, 2015 I found a "Dope from Hope" collection. See page 66-67 for the comments about the B-2 network https://community.klipsch.com/index.php?app=core&module=attach§ion=attach&attach_id=47088 Quote Link to comment Share on other sites More sharing options...
muel Posted June 17, 2015 Author Share Posted June 17, 2015 Here is the actual text: 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 DB:rh 1 Quote Link to comment Share on other sites More sharing options...
Deang Posted June 17, 2015 Share Posted June 17, 2015 So, there you have it. 1 Quote Link to comment Share on other sites More sharing options...
muel Posted June 17, 2015 Author Share Posted June 17, 2015 Getting the parts for the B2 networks... I can see that it really doesn't pay to build these yourself. Those parts add up fast! Quote Link to comment Share on other sites More sharing options...
Thaddeus Smith Posted June 17, 2015 Share Posted June 17, 2015 Not if you want it done right.. 1 Quote Link to comment Share on other sites More sharing options...
Deang Posted June 17, 2015 Share Posted June 17, 2015 People often don't think about the fact that vendors get OEM pricing. We also already have all of the right tools. A good soldering station can set you back around a hundred dollars, and the discounts on the parts can be anywhere from 20-40%. By the time you buy everything you need, you're usually within a hundred or less of just having one of us do it for you. I will say that if you plan on doing a lot of this kind of thing, you should probably invest in the tools and have at it. With time, you actually get good, and you can always go back and redo your early work if you aren't that happy with the results. If you don't think you're capable of producing something half way decently built, don't do it. Quote Link to comment Share on other sites More sharing options...
Schu Posted June 17, 2015 Share Posted June 17, 2015 ^specially electrical parts... even if they are passive. Quote Link to comment Share on other sites More sharing options...
Thaddeus Smith Posted June 17, 2015 Share Posted June 17, 2015 i give my B2's a sweet kiss goodnight after I wrap up every listening session. true story. Quote Link to comment Share on other sites More sharing options...
Schu Posted June 17, 2015 Share Posted June 17, 2015 ^hahahaha... nice! They are indeed sent from heaven. Quote Link to comment Share on other sites More sharing options...
muel Posted June 17, 2015 Author Share Posted June 17, 2015 People often don't think about the fact that vendors get OEM pricing. We also already have all of the right tools. A good soldering station can set you back around a hundred dollars, and the discounts on the parts can be anywhere from 20-40%. By the time you buy everything you need, you're usually within a hundred or less of just having one of us do it for you. I will say that if you plan on doing a lot of this kind of thing, you should probably invest in the tools and have at it. With time, you actually get good, and you can always go back and redo your early work if you aren't that happy with the results. If you don't think you're capable of producing something half way decently built, don't do it. So far so good anyway. I take things so slow and study what I am doing so much that I probably take four times as long or more to get anything done. I'm just having fun so I don't really care how long it takes. I had enough experience building serial cables years ago that I can usually get this kind of stuff done OK. I wanted those connections to look good even though they were going to be covered up. I love the networks that you built for me Dean! We will have to see what's next... I'm interested to see when Jupiter finally releases their new round caps. Their copper caps are a bit out of range. 1 Quote Link to comment Share on other sites More sharing options...
BEC Posted June 18, 2015 Share Posted June 18, 2015 Bob, If you are following this thread, would you please be so kind as to attach the Dope from Hope which explains the reasons for the change from the Type B to the Type B2. I really don't build the Type B anymore. If possible, I almost always try to move a person to the B2. Here you go. Bob Crites DFHB2.pdf Quote Link to comment Share on other sites More sharing options...
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