Firstly, yes we made an error with not sealing the binding posts. That was a QC error which has now been addressed in manufacturing procedures. We normally apply sealant. We didn't pick it up on the post manufacture test for that particular pair due to us using very tight fitting banana plugs which seal the hole. Please note I gave the customer significant compensation for his time to fix the problem and seal the posts himself. Our mistake and error for which I apologised.
The rest of it, however is nonsense.
The customer initially claimed and concluded from his measurements that there was a faulty passive radiator. Incorrect. The 380 Hz distortion blip is caused by a fundamental resonance of the woofer frame and magnet assembly. It will be seen in *ALL* designs.
Please look at these plots of Amirs previous purifi speaker tests.
Exactly the same issue.
Further more I have had discussions with both Lars Risbo and Bruno Putzeys from Purifi regarding it. They acknowledge the issue and together we have worked out a solution regarding the driver mounting that I am waiting for them to implement in manufacture.
In the meantime we have implemented a mitigation, not an elimination, but a significant reduction. You will note that that one of the pair of this customers speakers didn't have a high distortion blip at 380hz. The reason for this is because it was the speaker he had *not* been disassembled. By disassembling the customer messed up the torque values of the woofer mounting bolts (threadlocked btw) on the speaker with the subsequently higher distortion. Hint, the driver resonance couples into the cabinet.
He has a complete lack of understanding of vibration and speaker design. His test where he thinks he proved there is no driver resonance is completely flawed. He sits the speaker on the cabinet. The driver needs to be *stiffly* mounted by its frame, not sat on the heavy magnet to perform this test. The resonance is set up by the specific spring , mass and stiffness of the overall assembly. The magnet must be hanging from the frame not damped by being sat on a surface.
All rubber mounts were fitted. He obviously lost one during his disassembly. It would have been impossible to tighten that particular driver bolt without it fitted. The bolt would have flopped around loose and fallen out without it. We didn’t miss that in production.
Secondly further sealing is not required with these well nuts as the nut pulls into the hole and squeezes the rubber out completely blocking the hole. He also refitted the rubber well nuts incorrectly as their flange should sit inside the hole in this design. If not the flange will be proud of the surface and cause potential air leaks, which I also suspect he created by his incorrect fitment.
There is no air leak around the rubber mounting well nuts or indeed the tweeter. This can be demonstrated quite simply by depressing the woofer. The passive radiators will push out as you have compressed the air in the cabinet. If there is a leak the passive radiators will slowly return to their rest position. They dont. They stay pushed out.
The wiring had been disturbed by the customers disassembly. At manufacture it is tucked securely behind the damping material into the cabinet corners. The guy has pulled it out.
Fundamentally this customer is incompetent to make these assessments claims and caused problems by his disassembly of the speaker. He appears to be a “fiddler/tweaker” who thinks he understands whats going on.
I can send some links. Just got back home from a heck of a day. I'll have to go out to the garage see what I have been using lately. I have used many types over the years. I have even used sheet metal screws and cheap PartsExpress wood screws with no issues.Can you link some screws you can recommend with MDF? I never had any luck getting screws to grip well in MDF, except when using 6mm SPAX, which is obviously not feasible for loudspeakers.
I'm using 3.5x20mm SPAX like in the pic below, which only work if you have at least 15mm of material to screw into and then you still have to be extremely careful. Of course I don't pre-drill holes. I moved on to a different, superior material anyways, but I'm still curious.
He is not doing that.I find it bemusing that March Audio would criticise measurements taken by someone using a Klippel system. If I recall correctly, March Audio tests his speakers by sitting them on a tall ladder in an open field on a not so windy day
Also useful for screwing with a friend.Please don't edit posts in retrospect unless it is a grammatical error.
Perhaps Alan has some points?? However he should want to talk to the gentleman who made the measurements 1st hand! To make assumptions and attack the measurement data without 1st having a conversation with the other measurement person might not be a wise move?? To miss a leak in a 5K plus speaker does not bode well for the brand. Even if that turns out to be an only problem????? That means someone missed a production step & it was not caught? Also to ship with a known resonance in the woofer frame is not good? It sound like he had developed a partial fix but it sounds like a ban aid? I'm not saying there were not other issues present??I find it bemusing that March Audio would criticise measurements taken by someone using a Klippel system. If I recall correctly, March Audio tests his speakers by sitting them on a tall ladder in an open field on a not so windy day
This is the graph from OP that needs answering:
I run into this all the time. I show problem in a product and the answer from the company is I don't know what I am doing. Talking isn't going to help with that. What helps is replicating the reviewer measurement and showing different/better results. We have seen no attempt of this. Words are not going to do any good.
This is the graph from OP that needs answering:
There is some resonance in both but one is far cleaner than the other. Why? Clearly method of construction impacts this.
I'm not arguing but this might answer the question.
Nobody mentioned NFS, Massimo said “a Klippel system”, and the OP post #1 right at the top (did you read it?) confirms this, “I am using Klippel Distortion Analyzer 2…”.
His story is not consistent with what is said in OP. He had no motivation to dig into the speaker if the distortion was not there to start.
Yes, believe me I get it and agree! I tried to take a middle of the road position on my 2nd post. I was hoping it might get back to Alan and he MIGHT RETHINK???? I agree based on his comments to date this seems unlikely. The sad fact is with his current attitude he is doing himself & the brand in! He also risks sending out more poor quality products? As I'm sure you know from working at Microsoft strict. quality control processes are so important.
Microsoft surface duo anyone
, Windows Vista?
I swear by all the about 80 reviews I've posted so far.
