krzys Posted November 15, 2006 Share Posted November 15, 2006 Like many others I wanted to try the Altec road for my Klipsch Cornwalls. I got a pair of 511b with 806a 16 ohm drivers. i was told that the diaphragms were replaced with P Audio new ones. I mesured the Altec horns and got some suprising results: There is a hudge hole in the Altec curve beetween 500 and 1600 Hz. I can not imagine that this is a typical response. Does anybody knows possible reasons like week Alnico magnet, bad diaphragm or is that the famous Altec sound ;-) Chris Quote Link to comment Share on other sites More sharing options...
sfogg Posted November 15, 2006 Share Posted November 15, 2006 Try reversing the phase of your Altec driver and remeasure. You might be out of phase with the woofer and causing a cancelation. If that doesn't do it either you magnets need to be recharged or your diaphragms are no good. Shawn Quote Link to comment Share on other sites More sharing options...
krzys Posted November 15, 2006 Author Share Posted November 15, 2006 Shawn thanks for your replay. As I understand it, the phase is out of context since I'm using a digital crossover and all other drivers were muted, no cancelation is possible. Is this behaviour typical of weak magnets ? Quote Link to comment Share on other sites More sharing options...
Guest " " Posted November 15, 2006 Share Posted November 15, 2006 see the discussion below. http://www.audioheritage.org/vbulletin/showthread.php?t=2550 Quote Link to comment Share on other sites More sharing options...
sfogg Posted November 15, 2006 Share Posted November 15, 2006 OK, didn't realize you were just measuring the Altec alone. In that case you are correct that phase has no bearing on the measurement. What is your crossover point and what slope? Have you tried measuring the driver run full range at low power? Keep the volume down and you can do this OK. That will give you the raw acoustic output of the driver/horn without worrying about how the crossover may be influening it. "Is this behaviour typical of weak magnets ?" I don't really know. All my Altecs are ferrite magnets so I've never had to deal with or measure a unit that might have a weakened magnet. As such I don't really know what the measurements of that would look like. I did have bad diaphragms in my Altec 288s and it caused them to roll off much to earlier on the top end and on the bottom end compared to new diaphragms. The other thing I don't know is how the P Audio diaphragms perform. They might simply not go as low as Altec diaphragms. Shawn Quote Link to comment Share on other sites More sharing options...
krzys Posted November 15, 2006 Author Share Posted November 15, 2006 I forgot to tell that the measurment was taken with full range mode using pink noise. The general cut off point are as expected ie arrond 500Hz on a horn and some 10 kHz. Next steps : try another diaphragm from Radian or GPA or just jump directyl to a 902 with quality diaphragm. In the meantime I can try the Klipsch driver but will need some holes since I have the three bolt version K57K (I think?). Chris Quote Link to comment Share on other sites More sharing options...
krzys Posted November 15, 2006 Author Share Posted November 15, 2006 Speakerfritz If I follow you, you are pointing the fact that the 806 is not well matched with a 511 at low cutoff. Maybe, but lot of people use them even at 400 Hz and I thought that it is true only for PA use when power handling is imporatnt. Chris Quote Link to comment Share on other sites More sharing options...
Guest " " Posted November 15, 2006 Share Posted November 15, 2006 While I have most of my altec material at home, I do have at hand this 511 and 811 pdf, which recommneds 500hz as the minimum recommended crossover for the 511. It also recommends usedwith a 902 series, 908 series, and 731 driver. Not really sure what the 1200hz recomendation for the 902 series driver is all about..... I would not infer that to mean that any Altec driver (i.e 802 series) is a recommended driver for the 511 horn. I also would not infer that the response curve at the lowest recomended frequency would be flat..... There is a lot of good info at the Altec link. Quote Link to comment Share on other sites More sharing options...
sfogg Posted November 15, 2006 Share Posted November 15, 2006 That literature was written when the 80x series was discontinued and the 90x series that replaced it was the current product. "I would not infer that to mean that any Altec driver (i.e 802 series) is a recommended driver for the 511 horn. " The 80x was used on 511s many times by Altec. For example the VOTT A7-500 before the 90x series was released would have had an 80x driver on them. That covers a lot of speakers. See this page: http://www.lansingheritage.org/html/altec/catalogs/1966-vott.htm Or this: http://www.lansingheritage.org/images/altec/catalogs/1975-pro/page_4.jpg etc..etc.... "I also would not infer that the response curve at the lowest recomended frequency would be flat....." The 511 loads to below 500hz. Can't say for a 806 but a 902/511 is good down to a little below 400hz before unloading/rolling off. Altec recommended crossing over above the unloading point, hence the 500hz crossover recomendation. Shawn Quote Link to comment Share on other sites More sharing options...
krzys Posted November 15, 2006 Author Share Posted November 15, 2006 As I know in the early years Altec has sold 511 with 806. The pair I got was original, green painted. In my perception the only diference between 802 and 806 is the magnet size thus the efficiency a bit higher fir the 802. This said I don't think this is the problem I have. The measurments was made at rather low level say 80-83 dB. I made a search in altec heritage forum . The demagentization sometimes occurs if alnico driver is driven very hard and even then the symptom is some loss of efficiency between 1 and 3 dB. Nobody has ever talked about frequency changes. Quote Link to comment Share on other sites More sharing options...
sfogg Posted November 15, 2006 Share Posted November 15, 2006 "Nobody has ever talked about frequency changes." Call Bill at Great Plains Audio and ask him about it. He can give you the scoop. Bad diaphragms can certainly change the bandwidth of the driver. See this thread for example: http://forums.klipsch.com/forums/thread/607801.aspx Bill can remagnatize the drivers and I think it is pretty inexpensive. He could also install new diaphragms at the same time if you desired that. Shawn Quote Link to comment Share on other sites More sharing options...
Guest " " Posted November 15, 2006 Share Posted November 15, 2006 sfogg The 806 is a variant of the 802 driver, not the 902...... The tech data for the 802/804 applies to the 806. I'd like to see a response plot for the 806 that shows roll offs not occuring until below 400hz. Quote Link to comment Share on other sites More sharing options...
krzys Posted November 15, 2006 Author Share Posted November 15, 2006 "Nobody has ever talked about frequency changes." Call Bill at Great Plains Audio and ask him about it. He can give you the scoop. Bad diaphragms can certainly change the bandwidth of the driver. See this thread for example: http://forums.klipsch.com/forums/thread/607801.aspx Bill can remagnatize the drivers and I think it is pretty inexpensive. He could also install new diaphragms at the same time if you desired that. Shawn Interesting thread. I'm wondering if I souldn't sell the 806 as is and get 902 instead. Seems more promising for good sound. Any comments anybody? Is alnico important ? I don't have experience with alnico drivers. Quote Link to comment Share on other sites More sharing options...
sfogg Posted November 15, 2006 Share Posted November 15, 2006 "The tech data for the 802/804 applies to the 806. " Which is why I posted it showing 80x series drivers being used on 511B horns... Shawn Quote Link to comment Share on other sites More sharing options...
sfogg Posted November 15, 2006 Share Posted November 15, 2006 "I'm wondering if I souldn't sell the 806 as is and get 902 instead." Might be cheaper (assuming you get 'good' 902s... get ones with bad diaphragms and you are back where you started) and you would gain some efficiency and I think top end response compared against what an 806 should be able to do and more bottom end then what you are getting out of the 806s you have. "Is alnico important ?" Some say yes, some say no. Shawn Quote Link to comment Share on other sites More sharing options...
cjgeraci Posted November 15, 2006 Share Posted November 15, 2006 "I'm wondering if I shouldn't sell the 806 as is and get 902 instead. Seems more promising for good sound. Any comments anybody? Is alnico important ? I don't have experience with alnico drivers." I originally considered replacing my 806As in my Altec Valencias with 902s, but then I spoke with Bill at Great Plains last year. He kind of chuckled when I asked about 902s and explained that the major advantage of the 902s would be extended frequency handling on the top end. However, according to Bill, good working 806As would perform just as well otherwise, even at the higher home audio volumes, and he said that most could not tell the difference (even on the upper end) between a good functioning 806 and 902. Some (including me) prefer the sweet sounds of those particular Alnico drivers (versus the later materials). I also run Beymas up top along with the 806As, and they have been sweet in the midrange. Admittedly, I am also running 811s with my 806As, but as many noted in here, the 806 was one of the driver of choice for 511s with VOTT for a number of years. So, unless you are thinking about going to two-ways, I would not expect to hear qualitative improvements with 902s over 806s. That being said, maybe you have a set of bad 806s, and I agree with Shawn that it would be worthwhile to call Bill and ask him about it. Kind of seems strange though. Wonder if you have a different problem somehow (although I do not know how). Maybe a problem with your active crossover??? I would hate for you to get rebult 902s or 806As and still have some problems in frequency response. Carl. Quote Link to comment Share on other sites More sharing options...
krzys Posted November 15, 2006 Author Share Posted November 15, 2006 Carl , the measurments were taken wideband without any crossover. I took those measurment many times and get consistent results. The Klipsch driver was performing as expected , without any drop and was measured in the same time. Both Altec drivers (having same new diaphrags ) performed in the same way. I must admit that I don't hear clearly this drop in my three way system. I also can equalize the driver with the digital crossover (parametric filters available) but prefer minimize the EQ. The most probable cause are diaphragms but it's hard to admit Quote Link to comment Share on other sites More sharing options...
Guinness Posted November 15, 2006 Share Posted November 15, 2006 I had 806-8A's running with 511b horns in a three way setup using Cornwalls as the woofer. I was very pleased with it. I then switched to 902's, thinking of going two way. So far, I am still running three way. I can't say that I noticed much difference going from the 806 to the 902 drivers using crossover frequencies of 600 and 6000 Hz. There must be something wrong with them. I also suggest contacting Bill at GPA. Quote Link to comment Share on other sites More sharing options...
TBrennan Posted November 15, 2006 Share Posted November 15, 2006 A proper 806 on the 511 will run right down to 500hz, no doubt about it. Your drivers are no longer 806s, with the PAudio diaphragms God knows what they are. My brand new GPA 902-16s sound just like the 45 year old 804s (early nomenclature of 806) they replaced in my AS-21s. But I'm 57 years old. If you really want the Altec road get proper diaphrams in the 806s (and get them remagged, if they've been blown ((and why else would they have replacement diaphragms)) you can assume the magnets are weak) and replace those K-33 woofers with 416s, the Altec woofers are just as important to good sound as the compression drivers. Then you'll have Altec Iconics in a Klipsch box. Quote Link to comment Share on other sites More sharing options...
krzys Posted November 16, 2006 Author Share Posted November 16, 2006 Do you guys see the graph in your browsers ? I only see it when I edit the post. If it isn't visible does somebody know the why? It is a jpg file. I I'm joining it again. Quote Link to comment Share on other sites More sharing options...
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