Posted by Roy on March 29, 2003 at 17:38:57:
In Reply to: Comments posted by Roger West on March 20, 2003 at 10:55:19:
I feel very unhappy having to write this reply to Rogers comments because I have the greatest respect for him and his superb speakers. Having owned a few speakers in the past and having auditioned many more I feel that my A3 Speakers to be the best I have ever heard.
Having read the comments I too find aspects of those comments that should be corrected.
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I enjoy reading the comments on SLOG. Sometimes, however, a comment is made that I feel needs correcting. I do not question the sincere intent of comments, so my comments should be taken as corrections to what I consider fallacious reasoning and not an attack upon a contributor. Recently, a contributor to SLOG, who recently received new panels, has had problems with them and has made comments on SLOG that I feel need to be corrected. The story starts when he received the panels and found the membrane tension too high. I sent him instructions on how to heat treat them, which he successfully accomplished. Within a couple of days the panels began exhibiting a series of stator insulation breakdowns, the cause of which will be a mystery until I can analyze them. The only clue we have is that the breakdowns are near where the stator wires are adhered to the horizontal ribs and are predominantly on the rear stator set (the panel half that the membrane is attached to). My feeling that the heat-treating process might possibly be a candidate as a cause of the stator insulation breakdown problem was a speculation, not an accusation, as there were no other possibilities that came to mind.
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After I received my new panels the base response was very poor, it rolled off rapidly from about 55Hz. After reporting this to Soundlab I was told that the membrane would relax over time but that the best and fastest solution to achieve optimum bass response was to heat treat the membrane.
After a few days I received a set of excellent instructions which I carried out. I posted my experiences on SLOG so that others could benefit from the process that I had carried out. I asked Soundlab for permission to have the instructions put in our articles section.
Very shortly afterwards my stator insulation breakdowns started. After exchanging emails about these breakdowns with Soundlab I was told by email:
“The risk taken by a customer doing the procedure is not our responsibility. There is absolutely no doubt in my mind that the break downs in the insulation and the resulting holes in the membrane are due to the heat treatment that you gave the panels. If we had done the work then by all means we would take responsibility for it.”
I thought that this was unfair and not my fault. I had simply carried out the instructions that I was given to rectify the bad base response.
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An event occurred two weeks ago that added another possibility. We had shipped panels to a customer and he experienced a similar problem. However, we were aware that the crates that the panels were packaged in were "flat-dropped" (panel back side toward the ground) from the bed of a truck just after being unloaded from the cold hold of an airliner. Several insulation breakdowns occurred very close to the junction of the ribs and the stator wires. I suggest that at the moment of impact the high inertial forces on the wires on the back half of the panel would momentarily cause the wires to bend downwards between supporting ribs. The sharp (90 degree) edges of the ribs would tend to concentrate great pressure on the stator insulation, which happens to be where the breakdowns occurred. Under these conditions it would be expected that damage to the stator insulation on the front panel half should be less because the initial impact would not push the wires toward their supporting ribs, but rather away from them, which is just the opposite case of the wires of the panel's back half. Quoting a comment taken from an email I received from the customer: "The first breakdowns happened to the rear stator tubes", which supports my suspicions.
The pernicious practice of flat-dropping crates has been a problem before on rare occasions. It is insidious in that the crate shows virtually no damage while the damage to the product can be considerable. I'm sure that the very cold temperatures of the cargo hold of a high altitude aircraft (it can be below -70F on international flights) could make the stator insulation more vulnerable to impact damage. It is very difficult to convince freight forwarding companies that it is their fault unless there was a witness. At this point, my feelings are that the damage in both cases was more than likely due to this mode of shipping abuse. It is not surprising that both we and the customer involved don't feel responsible for the damage. The breakdown may not be immediate if the impact does not fully break through the insulation as in the case of the customer's panels. It was more likely coincidence that the breakdowns started just after the membrane heat-treatment.
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To date I have had 16 breakdowns. Most of the breakdowns are at the glue joint on the cross braces excluding 4 that happened at the very bottom of both speakers. All of the current breakdowns are at the glue joint in line with the brace face. I can hear the tell tale starting noise of a new breakdown at the rear of speaker 1, it is at a glue joint but I can’t see it yet.
The first breakdown occurred on the rear of speaker 1 between the 2nd and 3rd braces. The second breakdown was on the rear of speaker 2 and the third breakdown occurred very close to the first breakdown. As the breakdowns progressed they showed no particular favor to where they occurred, front or back, top, middle or bottom.
The breakdowns to date are:
Speaker 1: 3 on the rear face behind the membrane and 4 on the front face in front of the membrane
Speaker 2: 4 on the rear face behind the membrane and 5 on the front face in front of the membrane.
The breakdowns are scattered about the entire surface without any real trend.
The 4 breakdowns at the very bottom of the speaker are a little different to the others. The stator tubing here is reinforced on the bottom brace with what appears to be clear heat shrink sleeve, it covers about 5/8” of the stator tube above the bottom brace. In these cases the breakdown appears to be located above the brace face where the reinforcement sleeve stops.
My panels are showing a reasonably even distribution of breakdowns between the front and the back of the speakers. Following the logic for the reason for the breakdowns my panels would have had to have been flat dropped on both the front face and the rear face on both speakers.
Once maybe but 4 times would take some doing
This theory does not explain the 4 breakdowns that have happened at the end of the reinforcement sleeve where the tubing is not supported by the brace.
I have not been asked by Soundlab to list where the breakdowns have occurred which I find surprising considering the new theory for the breakdowns.
The stator wires are very stiff. The distance between the braces on the first and third breakdowns is only 2 ¼”. The wire inside the tubing is actually 1.6mm hardened steel wire. It takes a lot of force to deflect it even a small amount at this distance. For those of you who are not conversant with the design, the top two braces are spaced at just under 2” apart, the brace spacing gets progressively greater to the bottom of the speaker where it is approximately 8 ¼”. This breakdown theory may be more appropriate for breakdowns towards the bottom of the speaker where the brace spacing is at its greatest and there is the least support for the tubing.
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Back to the comments of the customer. He has made some erroneous speculations about the damage of his panels that I feel need to be corrected. First, he suggests that a surfacant (primer) has been used to treat the surface of the stator insulation so that the adhesive adheres to it. He mentions the presence of a white residue as proof of this. Fact: we do not use a surfacant. The white residue is a micro-crystallization of the adhesive (cyanoacrylate) due to application of an adhesive accelerator. Being a good insulator, it does not affect on the performance of the panel.
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What I actually said was:
In places around the ribs and stator tubes there is a white residue. I suspected that a primer was used prior to gluing the stator tubes. This is necessary when bonding Polyolefins to enhance the adhesion. I suspected that this could also be contributing to the stator tube breakdowns, after all, it must be doing something to the surface to enhance the adhesion. Sound Lab says that no surfacants were used, well if that was the case I wonder what the white residue is then.
I do not say that the white residue is proof of the presence of primer. I stated that, Soundlab says no surfacants were used, well if that was the case I wonder what the white residue is then.
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The customer further states that the glue causes stress on the insulation and possibly damages it. Fact: the insulation has a low surface energy which makes it near impossible for cyanoacrylate to make a strong bond to it. This is actually a desired characteristic in our assembly as it eliminates any stress that could result from the adhesion process. The important point here is that if the adhesive doesn't bond to the insulation it cannot stress it. Furthermore, the adhesive is not a solvent of the insulation material and does not chemically attack it. In fact most acids won't even attack it. Continuing, the customer states that the stator wires would have less stress on them by placing notches in the ribs to hold them rather than using adhesive. Fact: The notches are designed such that the wires require a mild insertion force to install them. This force is not strong enough to invite damage to the insulation, but is sufficient to hold the wires in place during the manufacturing process. On the other hand, the adhesive approach is very similar in effect to the notched-rib approach as a consequence of the fact that the adhesive adheres well to the exposed rib surface between the wires but not to the insulation on the stator wires. Therefore, the adhesive forms a "notch" of precisely the same dimensions as the cross section of the insulated wire, hence there is no compressive force involved. The stator is held in place by a thin film of adhesive placed over the tops of the insulated wires at the point where they are adhered to the ribs. Thus, there is virtually zero stress on the insulation using the adhesive approach.
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We obviously have different opinions about the pros and cons of the two approaches and the causes of stress that I am describing. This is my reasoning.
My old panels are constructed using a notched rib approach and no glue is used to position the stator tubes to the ribs. The slots in the braces measure on average 0.114” wide, they are very accurately produced. The tubing has a greater tolerance and my samples measure between 0.106” and 0.109” dia, that is 0.005” minimum clearance when the tube is inserted into the notch, the stator tube slides easily in the notch. The tubing is kept in place in the notches by the sponge rubber spacer strips used in the panel construction. This sponge rubber gently presses the stator tube to the rear of the notch stopping any possibility of vibration. Each piece of tubing is supported by 13 cross braces. The tubing is fixed in place on the bottom cross brace only by a narrow line of glue. This method of construction allows the tubing to move independently to the frame structure. With the great temperature extremes that are present whilst shipping long distances (-70 degrees as stated here and I was also told –100 degrees F to 130 degrees F by email) and more normal temperature changes in homes the stator tubing can FLOAT within the complex frame structure as both the tubing and frame contract and expand at different rates. This method of construction is excellent. And it is the method of construction that Soundlab say they reverted back to last year. It is a shame that my panels have not been made using this method of construction.
The glued method of construction ties the tubing to the frame structure. The glue bond may not be perfect but it does grip the tubing at each brace firmly, each glue bond is 6mm long. The tubing is not free to slide within the glue bond. With temperature changes the frame will move a little trying to take the tubing with it, this is when STRESS comes into play. The maximum point of stress with be at the glue joints or very close to them on every cross brace. This is the method used to construct my new panels. My new panels keep breaking down.
On my new panels I have noticed a few big blobs of glue sticking to the outside face of the tubing. They obviously got their by mistake and are doing no harm. I tried to prise one of them off with my finger nail, it didn’t budge. The glue blobs are holding on well. I did not try using a tool for fear of inviting another breakdown.
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Finally, the customer states that a destructive degree of force is caused by straightening out the mild curvature that occurs in the stator insulation as a result of taking it off of a spool. Fact: a mild curvature does exist in the insulation when it is de-spooled as would be expected. However, the material is quite flexible and the force required to straighten it is very minimal. I have demonstrated that the weight of a plastic ball-point pen is sufficient to remove the curvature of a 12" length of the insulation, hardly enough to cause significant stress. Furthermore, after the insulation has been threaded onto the wire over a reasonable time period the curvature relaxes and ultimately disappears. I won't quote some of the remarks that were made by people to whom this was demonstrated when I told them that someone had the opinion that the stress required to straighten the insulation is high enough to do damage.
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This is what I actually said:
Another factor that I think contributes to breakdowns is that coiled tube is used to slide over the stator wire. The tube used is considerably stiffer than the previous flexible PVC tube used, this new tubing would be in STRESS when straightened and passed over the stator wire. Purchasing straight cut lengths of extruded tube costs no more than coiled tubing.
The tubing used is only 1/8” in diameter. It does not need a great force to straighten it. The previous flexible PVC tubing used has a plastisiser in it, this tubing is naturally flaccid and it is normal to buy it in coil form. The Polyolefin used for the new tubing does not have a plastisiser in it, it is naturally more stiff and it has a memory. I agree totally with the statement that the memory will disappear in time but in that intervening period the side of the tubing that was the inside part of the curvature when the tubing was in the coiled state will now be in tension when the tube is straightened.
The problem is that as stated earlier is that the temperature in airplane holds can be below -70F (and I was also told –100 degrees F to 130 degrees F by email), on international flights. Any added stress here can only CONTRIBUTE to the stress induced from glue joint construction method. This cannot help matters.
The main point of this is that the Polyolefin tubing comes off the extruding machine dead straight and it can be cut of at the lengths required automatically at no extra charge. If a production route costs no more and can only give benefits, why not go for it. It also saves on a cutting operation when the panels are built. This is good practice.
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People are certainly free to entertain their opinions, but when they are published, and we feel that they are misleading, it is necessary to correct them. Especially, if they are capable of damaging the confidence of our customers. With respect to the customer that has written his opinions to SLOG, we honestly do not feel responsible for the damage of his panels, otherwise we would have rectified it long ago. To my knowledge, in his communications to me and SLOG, he has not considered the possibility of hidden shipping damage, which I feel to be the most likely failure mode. I'm sure that had he been suspicious of this possibility he would have appealed to the freight forwarder for redress. Maybe, it's not too late. Nevertheless, we offered him our standard warranty repair.
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The choice of shipper was left to Soundlab. After reading the text above I thought it sensible to contact the shipper, I telephoned the company concerned and they said that all claims had to be registered with them within 14 days of delivery. The crates were delivered in good order and I signed for them as such. I was informed that even if I had made a claim against the shipper within the time period an insurance inspector would probably have come out but that the possibility of a claim being successful was negligible because the crates showed no sign of damage and in any case they had been signed for in good order. The conversation with the shipper then changed to the packaging materials used inside the crate if the goods are likely to be damaged by rough handling.
If it’s a known problem that the shipper drops these crates from time to time and that Soundlab consider that damage to the speaker can result from this, especially if the goods are exposed to large temperature changes on international deliveries then I would suggest that action needs to be taken to modify the packaging. It would appear that it is difficult or impossible to claim against the shipper because of the lack of damage to the crate. Surely the packaging methods should be reviewed if Soundlab suspect that damage is possible through rough handling on international deliveries. It may be that the thickness of the crate would need to be increased slightly to accommodate a thicker alternative packing material that is more absorbent to shock. Perhaps all it needs is an alternative packing foam in the same crate. My panels were surrounded with strips of expanded polystyrene.
Three warranty types were offered to me successively after I complained.
1st warranty. I was offered the wholesale price to have my panels remanufactured. Who had to pay the international shipping costs was not mentioned.
2nd warranty. Soundlab would rebuild my panels at no charge but I would have to bear all the international shipping costs.
3rd warranty. Soundlab would rebuild my panels at no charge but I have to pay the international shipping costs to Soundlab.
My panels did not perform properly from the day I opened the crates.
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I might also mention that the customer gave a warning on SLOG not to heat treat a membrane if Sound Lab instructs them to do so. The heat treatment process is rather simple, but one must follow strict directions so as not to damage the membrane or stator insulation. We heat treat every panel we manufacture. It rarely needs to be done again. If it is required we are careful to make certain that the customer is capable of doing the job correctly. Otherwise, we suggest that the panel be sent to the factory to have it done. In the particular case of the customer, we recommended it as he certainly appeared to have the capability. In fact, according to his testimony, he accomplished the job properly.
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The heat treatment instructions given are well written and the results that I obtained had the desired result. Heat treatment works very very well.
The text above says:
“but one must follow strict directions so as not to damage the membrane or stator insulation”
The instructions given to me to follow last November, identical to the ones in our articles section passed on by Soundlab do not warn against possible damage to stator insulation. The instructions only warn against burning holes in the membrane with the heat gun.
The reply I had from Soundlab after carrying out the procedure was:
“The risk taken by a customer doing the procedure is not our responsibility. There is absolutely no doubt in my mind that the break downs in the insulation and the resulting holes in the membrane are due to the heat treatment that you gave the panels. If we had done the work then by all means we would take responsibility for it.”
All I did was to follow instructions and I got the blame.
Until I read this latest post I was not aware that Soundlab was starting to attribute the blame for the breakdowns away from my action in heat treating my panels as instructed over to the Shipper for transporting the panels.
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The insulation material that we are now using has the finest characteristics of any that we have ever used. We have had over a year of full production experience with it and over three years of field experience with it. With the exception of the two cases mentioned and two cases where the insulation was externally cut, there have been no failures whatsoever. I have yet to find a failure that can be attributed to the insulation itself. It has demonstrated by far the highest reliability of any material that we have ever worked with. Concerning my remarks, if anyone wishes to visit our premises I will be most willing to demonstrate the substance of them.
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I am sure that the new insulation is excellent.
Roger has told us all in his previous post to SLOG that he has reverted back to the notched rib method of construction. Unfortunately, my speaker panels were not produced using this latest production method. If they had been produced using the new method, I am sure that even with the effects caused by extreme heat changes on international deliveries and the odd knock by the shipper the panels would have performed flawlessly and my sorry tales would be non existent.
You would think that with all these problems I would want to change speakers, well I don’t. I am a committed Soundlab Speaker user, probably for life. If I was asked to recommend the best speaker capable of realistically reproducing voice and real instruments, I would respond – Soundlab.