Guest " " Posted June 23, 2006 Share Posted June 23, 2006 Well, after listening to these 902 drivers for a while now, I'm really liking what I'm hearing. Their top end kind of reminds me of the alnico K77s, except a bit more refined. Last night, I played Madonna's latest CD, and I have to admit, these Altec drivers/horns did an excellent job. I was running the system at a sustained 101dB in the sweet spot, and I was very impressed and pleased with the sound. Even my "other" brother who isn't to fond of horns said that he really likes this combination. He said "Finally, a set of horns that don't chase you out of the room!" very good example of "not" following the party line, and getting good return on investments. what I like about this project is that no one was able to jump in and offer to sell you something. You broke the traditional upgrade "tempplate" and did something different. whats next on the list to try? Quote Link to comment Share on other sites More sharing options...
Deang Posted June 23, 2006 Share Posted June 23, 2006 Too funny. Quote Link to comment Share on other sites More sharing options...
steamer Posted June 23, 2006 Share Posted June 23, 2006 Well, after listening to these 902 drivers for a while now, I'm really liking what I'm hearing. Their top end kind of reminds me of the alnico K77s, except a bit more refined. Last night, I played Madonna's latest CD, and I have to admit, these Altec drivers/horns did an excellent job. I was running the system at a sustained 101dB in the sweet spot, and I was very impressed and pleased with the sound. Even my "other" brother who isn't to fond of horns said that he really likes this combination. He said "Finally, a set of horns that don't chase you out of the room!" Charles, Glad your starting to like the combo.When you said yesterday that they seemed a little to rolled off I thought to myself he needs to give it some time.The sound is different from what you are used to.You might have to adjust the position of the 511's to maximize the sound.The one driver covering so much territory probably has a different dispersion into the room(highs).I would be curious to see on/off axis measurements.In my system off axis does fall off but if Im not on axis then I am not ctiticaly listening.There also seems to be more roll off in the vertical vs. horizontal plane.That might have more to do with the position chosen for my 511's which are now about 60" in height and pointed down to the sweet spot 12' away. Greg Quote Link to comment Share on other sites More sharing options...
chops Posted June 23, 2006 Author Share Posted June 23, 2006 Well, after listening to these 902 drivers for a while now, I'm really liking what I'm hearing. Their top end kind of reminds me of the alnico K77s, except a bit more refined. Last night, I played Madonna's latest CD, and I have to admit, these Altec drivers/horns did an excellent job. I was running the system at a sustained 101dB in the sweet spot, and I was very impressed and pleased with the sound. Even my "other" brother who isn't to fond of horns said that he really likes this combination. He said "Finally, a set of horns that don't chase you out of the room!" Charles, Glad your starting to like the combo.When you said yesterday that they seemed a little to rolled off I thought to myself he needs to give it some time.The sound is different from what you are used to.You might have to adjust the position of the 511's to maximize the sound.The one driver covering so much territory probably has a different dispersion into the room(highs).I would be curious to see on/off axis measurements.In my system off axis does fall off but if Im not on axis then I am not ctiticaly listening.There also seems to be more roll off in the vertical vs. horizontal plane.That might have more to do with the position chosen for my 511's which are now about 60" in height and pointed down to the sweet spot 12' away. Greg Greg, Actually, that Madonna CD is recorded fairly bright, so the 902s sounded pretty good. Now with other CD where they "should" sound right, the 902s are rolled off a little too much. To be honest, they sound more like the K77s BEFORE I replaced the old caps. I should kill myself for even doing it, but I'm using tone controls! YUCK! I have the treble turned up to +3dB, and it sounds better. However, the thing that sucks most about it is that the treble control is centered at 10kHz, where I DON'T need boosting. So I'm stuck at either staying 2-way and getting a parametric EQ to gently boost from about 15kHz and up, OR go back to 3-way and use the CT125s again to fill out the spectrum. Most likely, I'l go with the tweeters. [*-)] Quote Link to comment Share on other sites More sharing options...
Guest " " Posted June 23, 2006 Share Posted June 23, 2006 Well, after listening to these 902 drivers for a while now, I'm really liking what I'm hearing. Their top end kind of reminds me of the alnico K77s, except a bit more refined. Last night, I played Madonna's latest CD, and I have to admit, these Altec drivers/horns did an excellent job. I was running the system at a sustained 101dB in the sweet spot, and I was very impressed and pleased with the sound. Even my "other" brother who isn't to fond of horns said that he really likes this combination. He said "Finally, a set of horns that don't chase you out of the room!" Charles, Glad your starting to like the combo.When you said yesterday that they seemed a little to rolled off I thought to myself he needs to give it some time.The sound is different from what you are used to.You might have to adjust the position of the 511's to maximize the sound.The one driver covering so much territory probably has a different dispersion into the room(highs).I would be curious to see on/off axis measurements.In my system off axis does fall off but if Im not on axis then I am not ctiticaly listening.There also seems to be more roll off in the vertical vs. horizontal plane.That might have more to do with the position chosen for my 511's which are now about 60" in height and pointed down to the sweet spot 12' away. Greg Greg, Actually, that Madonna CD is recorded fairly bright, so the 902s sounded pretty good. Now with other CD where they "should" sound right, the 902s are rolled off a little too much. To be honest, they sound more like the K77s BEFORE I replaced the old caps. I should kill myself for even doing it, but I'm using tone controls! YUCK! I have the treble turned up to +3dB, and it sounds better. However, the thing that sucks most about it is that the treble control is centered at 10kHz, where I DON'T need boosting. So I'm stuck at either staying 2-way and getting a parametric EQ to gently boost from about 15kHz and up, OR go back to 3-way and use the CT125s again to fill out the spectrum. Most likely, I'l go with the tweeters. [*-)] You should look into using a Tweeter attenuator vs using an autoformer. if you want some intresting reading....check Al's site on his Tweeter attenuator modification. Quote Link to comment Share on other sites More sharing options...
Deang Posted June 23, 2006 Share Posted June 23, 2006 Why do you keep saying that? Al's tweeter attenuator works the same way as an autoformer does with a 20 ohm resistor strapped between common and input. It basically IS an autoformer. Also, that unit is designed to be used with tweeters more sensitive than the K-77. If your using the K-77, or Bob's replacement tweeter -- you don't need it! Quote Link to comment Share on other sites More sharing options...
Guest " " Posted June 23, 2006 Share Posted June 23, 2006 Why do you keep saying that? Al's tweeter attenuator works the same way as an autoformer does with a 20 ohm resistor strapped between common and input. It basically IS an autoformer. Also, that unit is designed to be used with tweeters more sensitive than the K-77. If your using the K-77, or Bob's replacement tweeter -- you don't need it! I like to look at options outside the standard "template" The application is about the altec horn driver Chops is working with, not a k-77. The spec's for the transformers used in attenuators are pretty impressive. 10hz - 40khz +- .5db and they are designed for very very very low loss. Does anyone have the specs for the T2A autoformer? x htz to x htz +- ?db Take a look at the schematic representation of the autoformer. there is no possible combinations that do not result in a drop, and each possible combination has a clear inductive value indicated (cost penaltiy). The cost penalty of using a tweeter attenuator is only .5 db. Quote Link to comment Share on other sites More sharing options...
Deang Posted June 23, 2006 Share Posted June 23, 2006 The application is about the altec horn driver Chops is working with, not a k-77. Ah, I see. The spec's for the transformers used in attenuators are pretty impressive. 10hz - 40khz +- .5db and they are designed for very very very low loss. By their very nature, autoformers are low loss. However, I don't how the standard units we use compare to Al's attenuator. Something to consider is that the attenuator may saturate at the power levels used by a midrange driver. We will have to wait and see what Al says. Does anyone have the specs for the T2A autoformer? x htz to x htz +- ?db I've never seen them. I don't know how much it matters, but the networks that we build and offer don't use T2A's -- all of us are using updated units by Universal Transformer (models 3619 and 3636). Take a look at the schematic representation of the autoformer. there is no possible combinations that do not result in a drop... I'm not sure what you are saying here. The whole point of an autoformer is to attenuate the signal, so of course there is "a drop" -- I mean, that's what they do. Am I being obtuse? ...and each possible combination has a clear inductive value indicated (cost penalty). I'm having difficulty seeing how that applies. Of course, it wouldn't be the first time for that kind of thing. Quote Link to comment Share on other sites More sharing options...
sfogg Posted June 23, 2006 Share Posted June 23, 2006 "Take a look at the schematic representation of the autoformer. there is no possible combinations that do not result in a drop, and each possible combination has a clear inductive value indicated (cost penaltiy). " You are missing the point of why the autoformer is in the circuit at all. The whole point of putting the autoformer into the circuit IS to drop the audio level. Without that 'loss' you would have a very unbalanced speaker. A 902 needs to be dialed *way* back to match the K33 in a Cornwall. You likely need around 10dB of so of attenuation on the 902 to get its level matched up with the K33 in a Cornwall. Al's tweeter autoformer is built for tweeters. It doesn't have the power handling ability of the larger autoformers that are intended to be run much lower in frequency. I tested one of Bob's autoformers and it was flat to at least 40kHz. No worries at all running it full range. Ditto the larger autoformers Al uses too. I ran two way with a 902/511B that way for about 2 years. Shawn Quote Link to comment Share on other sites More sharing options...
BEC Posted June 23, 2006 Share Posted June 23, 2006 Perhaps this will help. This is a trace of an AL-3/AK-3 crossover showing the voltage outputs of the three sections of the filter. The blue line is of the squawker output after it has been attenuated by the autotransformer. The red line is the tweeter output voltage that has not been through the autotransformer. The end of this trace is at 25 khz. We see nothing here as frequency increases except the uniform attenuation of the squawker signal. Bob Crites Quote Link to comment Share on other sites More sharing options...
Guest " " Posted June 23, 2006 Share Posted June 23, 2006 Perhaps this will help. This is a trace of an AL-3/AK-3 crossover showing the voltage outputs of the three sections of the filter. The blue line is of the squawker output after it has been attenuated by the autotransformer. The red line is the tweeter output voltage that has not been through the autotransformer. The end of this trace is at 25 khz. We see nothing here as frequency increases except the uniform attenuation of the squawker signal. Bob Crites Sounds like you just tried a hand of the old shell game with me. Consider yourself caught. Why would I compare the green to the red. Green is squaker going thru the autoformer, red is tweeter not going thru the autoformer. It would be intresting to see the same graph with a red line showing tweeter going thru the autoformer and a green line showing tweeter not going thru the autoformer. Quote Link to comment Share on other sites More sharing options...
BEC Posted June 23, 2006 Share Posted June 23, 2006 Perhaps this will help. This is a trace of an AL-3/AK-3 crossover showing the voltage outputs of the three sections of the filter. The blue line is of the squawker output after it has been attenuated by the autotransformer. The red line is the tweeter output voltage that has not been through the autotransformer. The end of this trace is at 25 khz. We see nothing here as frequency increases except the uniform attenuation of the squawker signal. Bob Crites Sounds like you just tried a hand of the old shell game with me. Consider yourself caught. Why would I compare the green to the red. Green is squaker going thru the autoformer, red is tweeter not going thru the autoformer. It would be intresting to see the same graph with a red line showing tweeter going thru the autoformer and a green line showing tweeter not going thru the autoformer. What? Bob Quote Link to comment Share on other sites More sharing options...
chops Posted June 23, 2006 Author Share Posted June 23, 2006 Sounds like you just tried a hand of the old shell game with me. Consider yourself caught. Why would I compare the green to the red. Green is squaker going thru the autoformer, red is tweeter not going thru the autoformer. It would be intresting to see the same graph with a red line showing tweeter going thru the autoformer and a green line showing tweeter not going thru the autoformer. No one is playing anything with you. It doesn't matter that the tweeter wasn't going through the autoformer. As you can CLEARLY see in Bob's plot, eventhough the squawker is attenuated throughout the entire range a few dBs, it does NOT drop lower at the top end of the range. IOW, it is NOT rolled off on the top end at all. It's really not that hard to understand. And unless you want me to cook Al's tweeter attenuator on the midrange, it's not going to work for me. Quote Link to comment Share on other sites More sharing options...
Deang Posted June 23, 2006 Share Posted June 23, 2006 Nevermind. Quote Link to comment Share on other sites More sharing options...
Duke Spinner Posted June 23, 2006 Share Posted June 23, 2006 anyway's Quote Link to comment Share on other sites More sharing options...
chops Posted June 23, 2006 Author Share Posted June 23, 2006 So.... If I go back to using the CT125s, what should I cross them over at? Quote Link to comment Share on other sites More sharing options...
sfogg Posted June 23, 2006 Share Posted June 23, 2006 Around 10Khz or maybe even a little higher. Shawn Quote Link to comment Share on other sites More sharing options...
Guest " " Posted June 23, 2006 Share Posted June 23, 2006 Sounds like you just tried a hand of the old shell game with me. Consider yourself caught. Why would I compare the green to the red. Green is squaker going thru the autoformer, red is tweeter not going thru the autoformer. It would be intresting to see the same graph with a red line showing tweeter going thru the autoformer and a green line showing tweeter not going thru the autoformer. No one is playing anything with you. It doesn't matter that the tweeter wasn't going through the autoformer. As you can CLEARLY see in Bob's plot, eventhough the squawker is attenuated throughout the entire range a few dBs, it does NOT drop lower at the top end of the range. IOW, it is NOT rolled off on the top end at all. It's really not that hard to understand. And unless you want me to cook Al's tweeter attenuator on the midrange, it's not going to work for me. Run the same plot with out the autoformer. Am I to believe there is no loss at all by uisng and autoformer. I think it will be at least 3db based on the schematic I posted earlier for the t2-a. no tap combination provide 0 loss. take a look at the diagram. There are 100 , 60, and 30 watt versions of attenuator's If folks want to use an autoformer to control the level of a tweeter I guess that is better than using an L-pad. Tweeter attenuator is my preference on the few occasions I needed to adjust. Loss factor on a attenuator is only .5 db from 10hz to 40khz. Quote Link to comment Share on other sites More sharing options...
sfogg Posted June 23, 2006 Share Posted June 23, 2006 "Run the same plot with out the autoformer. Am I to believe there is no loss at all by uisng and autoformer." No kidding the plot will be 'louder' without the autoformer. Again... the autoformer IS THERE FOR ITS ATTENUATION. The point is the squawker IS LOUDER (more efficient) THEN THE WOOFER AND THE TWEETER. It needs to be attenuated so that its output level matches the other drivers in the system. That is what the autoformer does... attenuates the squawker to match the other drivers in the system Learn what the part is for before you complain about it..... Shawn Quote Link to comment Share on other sites More sharing options...
IB Slammin Posted June 23, 2006 Share Posted June 23, 2006 Around 10Khz or maybe even a little higher. Shawn Not that I understand much more than about half of what has been said here, but having listened to the 902 for a few years now (3-way), it is MHO that one outstanding property of this driver is the upper mids. Cross it high Chopps. tc Quote Link to comment Share on other sites More sharing options...
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