Guest Robert M Posted February 5, 2007 Report Share Posted February 5, 2007 I've been listening to these quite a bit since I replaced the tweeters (see my other post) and one thing that I am noticing (not related to tweeter replacement) is that the woofer goes "out of control" at higher volumes. I'm not talking ear splitting, shake the walls loud, but solid loud, 11 o'clock or so on my HK730. They seem to be over-excursioning, but the bottom line is that they sound very distorted at high volumes. Can others confirm that this is a common occurrence? I'm experiencing the same thing on both, the foam is the "proper" type, got it from Simply Speakers and is the same as the picture on russwollman's birch veneered set. The only thing non-stock about the foam is that I installed on the front rather than the rear, but if you look at the Stereophile article, it appears that theirs was glued to the front and cut down from a 10" size as well. I'll be getting some more foam shortly to do another pair and glue to the back and see if that is the "problem". I'm kind of thinking that it's just the way these are, but I've never heard anyone else report this. Link to comment Share on other sites More sharing options...
dynaco_dan Posted February 6, 2007 Report Share Posted February 6, 2007 Hi Robert;Can you post a few photos please.You say in front of, instead of, in back of, can you clarify this comment, please?The Larger Advents had a masonite ring initially and was a reverse roll which was glued in back of this board.Sometimes I've seen thes surrounds glued incorrectly on the front which reduces the rearward travel of the cone movement.But this was not the case with the Smaller Advent woofer.Did you use shims when you did the re-foam job?How many watts does your amp put out at 4 ohms? Link to comment Share on other sites More sharing options...
Guest Robert M Posted February 6, 2007 Report Share Posted February 6, 2007 >Hi Robert;>>Can you post a few photos please.>>You say in front of, instead of, in back of, can you clarify>this comment, please?>>The Larger Advents had a masonite ring initially and was a>reverse roll which was glued in back of this board.>>Sometimes I've seen thes surrounds glued incorrectly on the>front which reduces the rearward travel of the cone movement.>>But this was not the case with the Smaller Advent woofer.>>Did you use shims when you did the re-foam job?>>How many watts does your amp put out at 4 ohms? I glued the inner ring of the foam to the front of the cone, rather than on the rear. It was easier and I was not experienced when I did this, I now try to always duplicate the original install. I centered the cone by feel and fixed w/ binder clamps then glued all around taking off and replacing the clamps. I now energize the speaker to help with alignment when I do this. Regardless, the woofer does not rub at all at full excursion or when bottomed out to as far as I dare push it. It also looks well centered. I experience this distortion on both speakers. I have tested them on two amps, the HK730 which has a 45 watt per channel rating into 8 ohms and a Kenwood KA-501, which has a 60 watt per channel rating. I have pushed speakers equally hard volume-wise on both these amps in the past, the SA is the only one that seems to get sloppy at high volumes.If someone could play these loudly with high-bass content and see how they behave, perhaps these speakers are just not meant to be pushed too hard.I hope to have a second set up and running in a week or two for comparison. Link to comment Share on other sites More sharing options...
dynaco_dan Posted February 6, 2007 Report Share Posted February 6, 2007 Hi again Robert;Can you post a few photos please.How many watts does your amp put out at 4 ohms? Your speakers are rated at 4 ohms not 8 ohms.Some s/s equipment put out more at 8 ohms than 4 ohms.Some equipment is unstable with lower than 6 ohm loads.>I now try to always duplicate the original install.A good practice.>I centered the cone by feel and fixed w/>binder clamps then glued all around taking off and replacing>the clamps. I now energize the speaker to help with alignment>when I do this. >Regardless, the woofer does not rub at all at full excursion or when bottomed out to as far as I dare push it.Are you referring to using music or pushing the cone with your hand? >It also looks well centered.Your cone centering is in the voice coil gap which you cannot see.By moving the surround a 1/4 inch in any direction the voice coil can rub or almost rub.> I experience this>distortion on both speakers. I have tested them on two amps,>the HK730 which has a 45 watt per channel rating into 8 ohms>and a Kenwood KA-501, which has a 60 watt per channel rating. >I have pushed speakers equally hard volume-wise on both these>amps in the past, the SA is the only one that seems to get>sloppy at high volumes.These speakers are very inefficient and also were never meant for high volume levels, as were all hifi speakers systems.Your amp may be clipping.Check out the Advent library and fusing information for The Smaller Advent.I think this would be a good idea for you.>If someone could play these loudly with high-bass content and>see how they behave, perhaps these speakers are just not meant>to be pushed too hard.The speakers can handle a lot of clean power peaks without distortion.If you use bass boost you are overdriving the amp and woofers.>I hope to have a second set up and running in a week or two>for comparison. I would wait to do that future repair unil this session is clearer. Link to comment Share on other sites More sharing options...
Pete B Posted February 6, 2007 Report Share Posted February 6, 2007 >I glued the inner ring of the foam to the front of the cone,>rather than on the rear. It was easier and I was not>experienced when I did this, I now try to always duplicate the>original install. I centered the cone by feel and fixed w/>binder clamps then glued all around taking off and replacing>the clamps. I now energize the speaker to help with alignment>when I do this. Regardless, the woofer does not rub at all at>full excursion or when bottomed out to as far as I dare push>it. It also looks well centered. I experience this>distortion on both speakers. I have tested them on two amps,>the HK730 which has a 45 watt per channel rating into 8 ohms>and a Kenwood KA-501, which has a 60 watt per channel rating. >I have pushed speakers equally hard volume-wise on both these>amps in the past, the SA is the only one that seems to get>sloppy at high volumes.>>If someone could play these loudly with high-bass content and>see how they behave, perhaps these speakers are just not meant>to be pushed too hard.>>I hope to have a second set up and running in a week or two>for comparison. Hi Robert,The Small Advent is a very inefficient speaker, and therefore your amplifiers probably do not have enough power. 100 to 150 W is probably more like it and remember this has to be into 4 ohms. I don't think the HK730 produces more power into 4 ohms than 8.You are probably clipping the amps.The old "High Fidelity" test report states that it could handle 100W steady state. Take this with a grain of salt, certainly not in the tweeter range or very low bass. And they state it could handle "pulse power peaks of up to 460W".You'll get significantly more output if you run a stacked pair, with the MaxSPL going up by 6 dB.Still, the Large Advent is more efficient and has higher MaxSPL. Link to comment Share on other sites More sharing options...
Doug G. Posted February 6, 2007 Report Share Posted February 6, 2007 Robert,Have you made absolutely sure there are no air leaks in the speakers?Doug Link to comment Share on other sites More sharing options...
dynaco_dan Posted February 6, 2007 Report Share Posted February 6, 2007 Hi again;The Larger and Smaller Advent use the same size 8/10 amp FNM Bussmann or FLM Littlefuse slow blow delayed fuse in an open style fuseholder.This places these in the same league as AR-2 series speakers in power handling capabilities.If you check out the Advent library there is a fusing information sheet.Also check out the various AR fusing sheets in the AR library as to regards to power handling with that size fuse.I think you will be surprised at what clean power the speakers can take before the fuses blow.The AR-7 were used as an example at the end of one fusing list, over 1,000 watt peaks for that little, itty, bitty, teeny, weeny, mity-mite speaker.If you can't talk while music is on, it's too loud. Link to comment Share on other sites More sharing options...
Guest Robert M Posted February 6, 2007 Report Share Posted February 6, 2007 I have re-foamed about 15 pair of woofers of various makes including 3 or 4 large advents of both varieties. I have never had an issue with the voice coil rubbing or woofers not functioning properly. I always test with tones to ensure proper operation after the refoam. I am careful and meticulous, there was a learning curve early on, these SA were probably the second set I did, but I'm still satisfied they were done as well as they could with the exception of the inner edge placed on the front of the woofer, rather than the stock rear. The speakers are properly sealed, as one would need for operation of an acoustic suspension system. There is a bit of resistance when the woofer is pressed in and it returns to its original position slowly, it is well sealed. Also note that I have driven other speakers at similar levels on the two amps I've tried, though those were 8 ohm, I do understand there is greater output into a 4 ohm load. I don't believe they are being overdriven, but I guess it remains a possibility.They give the appearance of over-exursioning. The front side gluing of the surround could play a part in this.The surround may have too large a roll. I've measured the gap between the cone and basket, it is 14mm. The surround that is being offered by various vendors is 16mm wide when measured from the front. I don't have any scraps from the original install. My other set had already been refoamed with a 10" generic 16mm wide roll, exactly like the stereophile picture. Is it possible that the roll on the original is either narrower or has less of a "hump"?I can't remember if it was the case with this particular set, but I have noticed some Large Advent woofers have sagging spiders. Perhaps some stiffness has been lost on that end? Link to comment Share on other sites More sharing options...
Guest Robert M Posted February 6, 2007 Report Share Posted February 6, 2007 By the way, photo of the units in question at this post:http://www.classicspeakerpages.net/dc/dcbo...g_id=1554&page= Link to comment Share on other sites More sharing options...
Pete B Posted February 8, 2007 Report Share Posted February 8, 2007 Thinking about this again, that offset introduced by gluing the foam on the wrong side might be contributing to the problem. I don't know the throw on the Small Advent woofer but it's probably similar to the Large, and as I noted in another thread 1/16" offset is half of the linear throw.Offset in the rest position will probably increase the asymmetry in the motor, and it causes rectification in the motion of the cone. This is analogous to DC offset in an electrical circuit. The zero crossing position will move under heavy excursion causing increased distortion.Do the woofers bottom?You might also have an intermittent voice coil, which will cause erratic cone motion and very high levels of distortion.Still, I think that you might not have enough power if your driving them hard. Link to comment Share on other sites More sharing options...
Stormy2021 Posted February 9, 2007 Report Share Posted February 9, 2007 Anybody ever used this Parts Express refoaming kit made specifically for the SA's nine inch woofer?www.partsexpress.com/pe/showdetl.cfm?&Partnumber=260-948I doubt that replacement dust cap has the same mass as the original, and the original's is as heavy as it is for a very specific reason, so if it is removed the woofer will not perform correctly. Link to comment Share on other sites More sharing options...
Guest Robert M Posted February 9, 2007 Report Share Posted February 9, 2007 What are you referring to as "throw"? The woofer moves much more than 1/8" in either direction when operating normally. So does the larger advent's woofer. So does just about any woofer I have ever seen. Are we talking about the same thing here? Link to comment Share on other sites More sharing options...
Pete B Posted February 10, 2007 Report Share Posted February 10, 2007 >What are you referring to as "throw"? The woofer>moves much more than 1/8" in either direction when>operating normally. So does the larger advent's woofer. So>does just about any woofer I have ever seen. Are we talking>about the same thing here?I'm speaking of the theoretically linear figure referred to as Xmax, you are speaking of Xmech, the absolute mechanical limit. Link to comment Share on other sites More sharing options...
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