UncleRobb Posted November 9, 2003 Share Posted November 9, 2003 After I had excellent experiences exchanging the coupling caps in some tube electronic (i.e. Bottlehead's Seduction phono stage) by Auricaps, I think of using these caps in the AA crossover of my La Scalas as well. I wonder how good the original caps are and if somebody has used Auricaps instead? I think that when it comes to the ratio of quality to price, the Auricaps are an excellent deal. By the way, I noticed that in his crossover network, Al puts several caps in parallel, and this in the signal pass(!) It this not something that generates a smearing of the signal? Regards, Robert Quote Link to comment Share on other sites More sharing options...
lynnm Posted November 9, 2003 Share Posted November 9, 2003 Although I suspect that the Auricaps are excellent I would suggest that you would get a lot more bang for the buck by reverting your type AA networks to the Type A configuration. I did that with my 82 Khorns and found those already beautiful sounding horns improved dramatically. The difference is mainly in an increase in smoothness in the midrange and high end and overall a somewhat more coherent sound. Bass response is unchanged as the A and the AA bass circuits are identical. Total cost of the mod ? About 10 cents for electricity and a tiny bit of solder. The beauty of this mod is that it is easily totally reversible if you attempt it and find you prefer the AA over the A ( you won't ). The mods applied to the Type A to create the Type AA were designed to reduce the number of tweeters being destroyed by the use of excessively powerful amplifiers which peaked in the 70's - ( DUH !! If a 440 Hemi performs better in a big car than a slant 6 then obviously a 300 w/ch amp is better for big speakers than a 30 w/ch amp ). If this mod interests you do a search under my username and use Type AA as the search term. Quote Link to comment Share on other sites More sharing options...
UncleRobb Posted November 9, 2003 Author Share Posted November 9, 2003 Lynnm, That sounds interesting (no pun intended ;-) ...anyway, I searched your post but didn't find too much. On 11/3/2003 you wrote of "...disabling the Xener diodes and eliminating the HF inductor in the Tweeter circuit..." I have the schematics and there are indeed two Zener diodes parallel to the tweeter. Thus, it is trivial to remove these. And then there is a 245uH inductor in some CLC filter. Does this one also have to go and could I then replace the two 2uF caps by one with 1uF? Of course, after making the mods, I can still use the Auricaps ;-) Thanks, Robert Quote Link to comment Share on other sites More sharing options...
UncleRobb Posted November 9, 2003 Author Share Posted November 9, 2003 Lynnm, That sounds interesting (no pun intended ;-) ...anyway, I searched your post but didn't find too much. On 11/3/2003 you wrote of "...disabling the Xener diodes and eliminating the HF inductor in the Tweeter circuit..." I have the schematics and there are indeed two Zener diodes parallel to the tweeter. Thus, it is trivial to remove these. And then there is a 245uH inductor in some CLC filter. Does this one also have to go and could I then replace the two 2uF caps by one with 1uF? Of course, after making the mods, I can still use the Auricaps ;-) Thanks, Robert Quote Link to comment Share on other sites More sharing options...
lynnm Posted November 10, 2003 Share Posted November 10, 2003 Here is a link to the Xover thread: Edit Hmmmm............ That turkey no workee ! Click on my avatar and then on 10 last topics and you see a link to the AA xover modification thread. Quote Link to comment Share on other sites More sharing options...
JohnA Posted November 10, 2003 Share Posted November 10, 2003 I put Hovlands in my Type AAs and love the result. I don't know how Auricaps are made, but better caps AND inductors help the Type AA. The Type A is a good design, but should not be used with a large amp, since accidents always happen. Quote Link to comment Share on other sites More sharing options...
Deang Posted November 10, 2003 Share Posted November 10, 2003 The price between the Hovland or RelCap PPT Theta, and the Auricap -- isn't enough to justify dropping down to the Auricap, which is not a film and foil type. Stay away from metallized polypropylenes in the HF circuit. Quote Link to comment Share on other sites More sharing options...
UncleRobb Posted November 10, 2003 Author Share Posted November 10, 2003 What is wrong with metallized foil caps? I would imagine that they are in general more compact than the film & foil ones without any drawback. Robert Quote Link to comment Share on other sites More sharing options...
UncleRobb Posted November 10, 2003 Author Share Posted November 10, 2003 Something else: I just had a look at the AA network in my La Scalas and somehow I cannot figure out how the board is attached to the speaker. All I see are several screws that hold the transformer, the inductors, one large cap, and the Zener diodes. Do these (or some of these) also hold the board itself? I hate to open the woofer department to find out more. Thanks, Robert Quote Link to comment Share on other sites More sharing options...
JohnA Posted November 11, 2003 Share Posted November 11, 2003 The screws that ho;d components don't hold anything else. There are 4 screws that are behind stuff that hold the board to the cabinet. Quote Link to comment Share on other sites More sharing options...
UncleRobb Posted November 11, 2003 Author Share Posted November 11, 2003 Thanks John! I found out that at least in one of my La Scalas, the crossover board is mounted by two 1" screws that are hidden behind the mount of the Zener diodes and the autotransformer. Unfortunately, the woofer leads are too short to allow me to take the board outside the speaker. But I am making progress... Robert Quote Link to comment Share on other sites More sharing options...
cwm Posted November 11, 2003 Share Posted November 11, 2003 This discussion leads me to wonder why some sing the praises of the "oil can caps" used in the "AA" and others? Further, I think the sweetness of some caps in small signal use i.e. pre/poweramps etc. does necessarily apply to large signal usage in speaker filter networks....I guess there is no harm in experimenting however, as its easy to revert back to the original stock xover components. Quote Link to comment Share on other sites More sharing options...
John Warren Posted November 11, 2003 Share Posted November 11, 2003 ---------------- On 11/10/2003 10:21:03 PM UncleRobb wrote: What is wrong with metallized foil caps? I would imagine that they are in general more compact than the film & foil ones without any drawback. Robert---------------- The metallized versions have the conductor (Aluminum, Copper) deposited onto the dielectric (polypropylene) using wet chemistry processes (i.e. like "plating"). The electrical conductivty of the metallization is not as good as a wrought foil (say like a sheet of Aluminum foil you would use to line a baking pan). Hovlands (for example) roll a sheet of Aluminum between the dielectric. Oil caps are lossy, why use them? Quote Link to comment Share on other sites More sharing options...
rtaylor Posted November 13, 2003 Share Posted November 13, 2003 John, don't know why some people prefer the oil cans to the better performing caps, haven't been able to A/B them myself. Seems there are good arguements to both sides of the coin. Just received a set of oil AA crossovers today to replace the AL's in my 86 lascalas. In the future will be building Al's ALK's and looking forward to comparing all these. Thanks Al for your generousity(SP?) in all that you do. Randy Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.