It's a new/small manufacturer. If we want to continue supporting companies like these, I would consider feeding back to manufacturer and await a response and for product/service improvement.
We live in a worried well world and sometimes I wonder whether pointing out a rectifable issue like this in an online forum causes more concern than confidence.
https://en.wikipedia.org/wiki/Diffusion_of_innovations
https://en.wikipedia.org/wiki/Technology_adoption_life_cycle
We live in a worried well world and sometimes I wonder whether pointing out a rectifable issue like this in an online forum causes more concern than confidence.
https://en.wikipedia.org/wiki/Diffusion_of_innovations
https://en.wikipedia.org/wiki/Technology_adoption_life_cycle
Every adopter of a new product is somehow a potential beta tester. I hope for Bliesma (and it's really nice product line) that they will show a responsive and positive approach to all design and manufacturing flaws that might occur on the user's fields of the real world. Otherwise, in 10 years Bliesma will be history and we will go on resorting to robust workhorses such as the aforementionned Audax TW034.
https://hificompass.com/en/speakers/measurements/audax/audax-tw034x0-13-textile-dome-tweeter
It's quite a tough competition, and Bliesma will have to prove it's competence not only in engineering, but also in troubleshooting now: Comparing e.g. the thd and waterfall data of this Audax published by hificompass, the Bliesma seems not to be revolutionary better than this oldie one. Instead, it's rather a welcomed, incremental progress, despite the delta in price, the more sofisticated materials and modelling ressources available today. Or you may turn it upside down: Audax did a really good job by then. And this TW034 has proven to be robust since then and by now. And Audax seems still alive today.
Make your choice. And cross your fingers for Bliesma.
https://hificompass.com/en/speakers/measurements/audax/audax-tw034x0-13-textile-dome-tweeter
It's quite a tough competition, and Bliesma will have to prove it's competence not only in engineering, but also in troubleshooting now: Comparing e.g. the thd and waterfall data of this Audax published by hificompass, the Bliesma seems not to be revolutionary better than this oldie one. Instead, it's rather a welcomed, incremental progress, despite the delta in price, the more sofisticated materials and modelling ressources available today. Or you may turn it upside down: Audax did a really good job by then. And this TW034 has proven to be robust since then and by now. And Audax seems still alive today.
Make your choice. And cross your fingers for Bliesma.
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Hi Profiguy,
I hope that you're not going to use an acetic acid cure RTV.
I am leaning towards the AlMg dome but I assume that the rest of the hardware is identical (assembly methods etc.). I wonder if I will have to deal with this as well.
You mention the SEAS T35C002, do you know if it uses ferrofluid?
Thanks!
I was about to post something exactly as tktran303.
I have a pair of T34B working perfectly since 2020, never experienced high frequency performance of this level other than with my old Apogee FR.
I will replace the T34B with quadruple T25B, similar method to the LX-521. I have already the T25B.
I have two pairs of M74B and just last week I got the pair 015/016 of the M142P.
All these drivers have measured perfectly and have had no problem whatsoever. The matching level of Bliesma is awesome, particularly their tweeters.
Any company can have QC issues but those are better sorted out through the respective channels as the dealer or the manufacturer directly.
I myself cross my fingers for Bliesma to keep going.
I have a pair of T34B working perfectly since 2020, never experienced high frequency performance of this level other than with my old Apogee FR.
I will replace the T34B with quadruple T25B, similar method to the LX-521. I have already the T25B.
I have two pairs of M74B and just last week I got the pair 015/016 of the M142P.
All these drivers have measured perfectly and have had no problem whatsoever. The matching level of Bliesma is awesome, particularly their tweeters.
Any company can have QC issues but those are better sorted out through the respective channels as the dealer or the manufacturer directly.
I myself cross my fingers for Bliesma to keep going.
I'm generally critical of any engineering, most of all my own.
And i kind of agree, Germany, Switzerland, and Japan in general are absolutely at the top when it comes to fit and finish and precision machining. Maybe not a large surprise, since that where all the real solid, precision cnc machines are engineered/built /manufactured, that the rest for the world use to build they're stuff, or copies thereof. In Germany Hermle and previous DMG for example.
When it comes to optics there is no real competition even, Schott makes the highest quality glass materials in the world, and Zeiss, Hensoldt, Schmidt&Bender, Leica etc, absolutely makes the best Optics in the world, for many industries, made from Schott lenses /raw material.
I have several "German" rifle scopes, Binos etc, actually, and the top quality Japanese lenses from Asian/US/European manufacturers can't compete in low light conditions for example from my experience. Although the Austrian Swarowski does.
Yes, but QC department usually gets a finished product they check, which will be handled gently and with care in this case.
They will not mar the finish on a finished product etc.
So they will naturally not apply high amounts of force to the backcap of the tweeters, to see if surface treatment or adhesive issues are present. Thereby this is a issue that is not eaasily detected by QC department at least.
Take one possibility:
Glue/adhesives are notoriously difficult to apply in a consistent amount by hand, so wether done by hand or machine it's often applied with a syringe/gun or similar.
2 component adhesives that does not cure before mixed is quite common, meaning you need a mixing valve or similar.
If that has a few issues before it fails completely, everything will look and seem normal even when done by hand even if the mixture is wrong. Leading to this exact issue.
Finding problems like this in QC is actually expensive.
If this is a recurring issue (likely not), implementing a extra step in the mfg process to fx pull on the backcup with a suction cup to preset /calibrated xx amount of force could be done.
Most would just look for a better mixing valve or increase the rate of changing them with new ones.
It just raises our final price.
After all you pay 300$ for the A, and 400$/€ for the B, a 34mm dome, that has better parameters and behavior then anything made by the competition, that sounds well behaved and clean at output levels that makes most dome tweeters crumble.
The magnet and motor design is absolutely excellent as seen by it's parameters, that are class leading. The response is good and fairly easy to work with and the sensitivity is high, CSD and distortion, sonograms etc are all excellent too.
We buy it after it has been through at least a importer/distributor, retailer and shippings, import taxes etc.
Meaning it is a 100-200$ product, The Be domes themselves cost some too.
Used to cost JBL about 100$ for theyre 4" Be, 2,2 grms diaphragms, back in the early 2000s apparently.
That is without a voice coil etc.
As for gluing them back together idk, i'd wait for the mfgs reply, they might want them back for examination in exchange for a new pair.
As for a glued backcup it's a easy solution, cost effective, and easy to find out if it has been tempered with for warranty.
If you leave them simply threaded that is not a good solution either, and leads to people tampering with them, like i would if they came, in my box like that 🙄
And that complicates Warranties and returns.
A threaded cap, back plate, threaded hole a set screw and a seal might be a better solutions but that requires quite a lot of extra machining operations, and/or more complicated moulds.
And i'm sure they still measure excellently as expected if fixed.
Mine at least came well packaged, side by side in cardboard/styrofoam with no room to move so, if caused by shipping i expect the package would have had visible scars when it arrived.
My pair survived shipping through Europe, sent by plane to the US , after some months of testing and torture and still, perform as they should from what i can see.
Interested to see how the M142s turn out, as the M74 can't really keep up with the T34 tweeters, versus other options.
I've bought, tested and used more than 20 pairs of different drivers from Bliesma till this day and everything has been good so far. I had a couple of drivers messed up during the shipping, but nothing major. I even broke one protective screen and damaged the dome. Contacted guys at Bliesma and they fixed it for me. So I think they can have some small problem as any other company, but I expect smaller and newer company would be able to get things right and adjust according to constructive feedback better than someone big.
You ignore one important fact, Hificompass measurements at least used to state that the CSDs have anomalies in the mid range 2-4 k ish, as can be seen in virtually all measurements in the same region.
Yet often not to the same degree in other measurements done by reputable sources so, if that is what you was aiming for also examine other measurements 😉 There are some tiny aretfacts there though anyays.
I know this is a hard pill to swallow for many Bliesma fans, but stuff happens and this situation is for me a common occurrence, even for higher end drivers. I've gotten just as much good as bad in terms of engineering, QC, and fiit/finish from all sorts of manufacturers, regardless of price and quantity.
You guys need to also understand the weather done here is currently in the high 110s degrees during the day and almost any adhesive will likely fail if subjected to harsh shipping and handling on top of it. There is no sign of mishandling though, and the rest of the drivers are ok. I'm not that concerned if they just need the back chambers reattached.
I don't see any issue using a common Acetate based RTV if used carefully and judiciously. None of it will come in conract with anything else, even the fumes, which will be minimized due to the proper quantity used in thr right area. No reason this isn't a good solution. I use this type of adhesive all the time in speakers and have had zero problems, regardless of materials in close vicinity. Its also a sensor safe RTV designed for automotive use. Its a proven type of sealant and has good adhesion to slick surfaces. I could use a urethane, but those can be aggressive to plated surfaces. I want the driver to remain serviceable, so no permanent type of adhesives that attack any materials or pver-adhere.
As for concerns with tampering, that's easily solved by a sticker/seal or a UV indicating seal, if that's a concern of a manufacturer. You guys also need to remember, the other back cup came off with my fingers pulling on it. That shouldn't happen. I also cam see that the slick surface of the plated motor asy isn't going to hold onto any adhesive of medium tenacity in strength. The surface is just plain too slippery. It needs some surface texture to have any decent mechanical grip, unless you use a reactive, or solvent based adhesive, which is too aggressive IMO around other glued materials inside the driver ie fumes migrating onto bonded areas and reacting. This is what a cyano based adhesive would do, which is highly reactive from its condensed byproducts when curing. Not the correct thing to use. An epoxy is also too aggressive and also won't work due to surface finish.
They clearly used a tbermoset urethane adhesive, which bonded well to the powder coated surface of rhe back chamber but it didn't bond with thr slick plated motor surface.
The back chambers were also a very loose fit without any interference or mechanical grip. There are notches machined into the back chamber flange which don't need to be there. Is suspect they used a larger headed fastener on the back motor yoke and decided to use other ones along the way. Again, no big deal. I could have used a solvent based glue here, but the fumes can migrate onto other glued surfaces and weaken them. Not a risk I want to take. Im just reatttaching some back chambers, which isn't rocket science. I dont want to wait weeks until stuff is shipped back and forth. I have cancer and don't have the time to wait. I want to enjoy these tweeters sooner than later and if that means gluing on some simple chambers, then no big deal. No need to hyper-analyze a simple situation. No need for complex materials analysis either.
I'll write to Bliesma if someone can give me the email address to contact them directly. I won't however wait for weeks to get new drivers shipped back and forth. Im not a patient man anymore these days. I just want to get listening to music sooner than later.
You guys need to also understand the weather done here is currently in the high 110s degrees during the day and almost any adhesive will likely fail if subjected to harsh shipping and handling on top of it. There is no sign of mishandling though, and the rest of the drivers are ok. I'm not that concerned if they just need the back chambers reattached.
I don't see any issue using a common Acetate based RTV if used carefully and judiciously. None of it will come in conract with anything else, even the fumes, which will be minimized due to the proper quantity used in thr right area. No reason this isn't a good solution. I use this type of adhesive all the time in speakers and have had zero problems, regardless of materials in close vicinity. Its also a sensor safe RTV designed for automotive use. Its a proven type of sealant and has good adhesion to slick surfaces. I could use a urethane, but those can be aggressive to plated surfaces. I want the driver to remain serviceable, so no permanent type of adhesives that attack any materials or pver-adhere.
As for concerns with tampering, that's easily solved by a sticker/seal or a UV indicating seal, if that's a concern of a manufacturer. You guys also need to remember, the other back cup came off with my fingers pulling on it. That shouldn't happen. I also cam see that the slick surface of the plated motor asy isn't going to hold onto any adhesive of medium tenacity in strength. The surface is just plain too slippery. It needs some surface texture to have any decent mechanical grip, unless you use a reactive, or solvent based adhesive, which is too aggressive IMO around other glued materials inside the driver ie fumes migrating onto bonded areas and reacting. This is what a cyano based adhesive would do, which is highly reactive from its condensed byproducts when curing. Not the correct thing to use. An epoxy is also too aggressive and also won't work due to surface finish.
They clearly used a tbermoset urethane adhesive, which bonded well to the powder coated surface of rhe back chamber but it didn't bond with thr slick plated motor surface.
The back chambers were also a very loose fit without any interference or mechanical grip. There are notches machined into the back chamber flange which don't need to be there. Is suspect they used a larger headed fastener on the back motor yoke and decided to use other ones along the way. Again, no big deal. I could have used a solvent based glue here, but the fumes can migrate onto other glued surfaces and weaken them. Not a risk I want to take. Im just reatttaching some back chambers, which isn't rocket science. I dont want to wait weeks until stuff is shipped back and forth. I have cancer and don't have the time to wait. I want to enjoy these tweeters sooner than later and if that means gluing on some simple chambers, then no big deal. No need to hyper-analyze a simple situation. No need for complex materials analysis either.
I'll write to Bliesma if someone can give me the email address to contact them directly. I won't however wait for weeks to get new drivers shipped back and forth. Im not a patient man anymore these days. I just want to get listening to music sooner than later.
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Could you please provide me with the email address you used to communicate with Bliesma? Thanks
Again, this is a simple matter of the adhesive not bonding to a slippery surface. Its a simple fix IMO provided the drivers are otherwise ok, which it appears they are based on a quick low input sinewave sweep. The rest of the driver is impeccably engineered and looks great. Its a simple fix for someone like me. No need to over-think or over-hype. It can happen to anyone considering the mechincal parameters.
I just used the email link on their web page to send them details on my situation. I'll post on here when I hear back from them.
Thank you for mentionning this. In German there is this not-so-nice saying: "Wer misst, misst Mist ...", and it is a real pity that many measurements which get published seem plagued by artefacts. I referred to Hificompass because you already did so in your own post No. 14 for the Bliesma and the Satori drivers. It might have been useful if you had commented this fact right away by then.
Good point, this potential fumes interference. It's really worth to take care. Anecdotically, I once made a quite tight transport box out of plywood for a dipole speaker system. For the prominent rear tweeter (a ferrofluid type Excel T29MF001) I milled out a small circular chamber into the inside plywood plane, so the faceplate of the tweeter became flush with the wooden surface, but the dome was free inside this small circular chamber. After having stored the speaker for some days inside this box, the dome surface was altered and had become sticky, and also the ferrofluid has gotten partially clogged. It was obvious that (formaldehyde?) fumes emanating from the plywood and concentrating inside this little dome chamber did the harm.
This raises a general concern when building boxes out of freshly manufactured composite wooden panels. Better let them take some fresh air for some moments before building closed chambers ... especially when resorting to such expensive drivers as these marvellous Bliesmas.
Attachments
Well, I'm not here to bash Bliesma. I just wanted to show what the driver looked like inside, as most people will never see this given the circumstances.
I believe in supporting small companies like this. Its what makes the world a better place. The solution to the problem is simple and I made it very clear that I don't have anything against their products, just the fact they didn't use the proper surface prep on a bonded surface.
I still love these drivers. I intend to keep them to enjoy for the short time I have left on this earth. I don't see an issue with posting something of this nature on line if its not meant to slander or defame the product. Its a simple fix. Nobody is perfect and ultimately its the outcome of the situation that matters most, how Bliesma handles the problem.
Yes, that's a serious concern when there can be cross contamination from adhesive fumes. I have alot of experience with vapor migration in adhesives. I worked for an aerospace company back in the 90s that was involved with the Hubble space telescope. I learned alot of stuff regarding materials compatibility then, which is why I'm so cautious with this stuff. So many potential incompatibilities when it comes to gluing stuff together with various adhesives and processes.
Formaldehyde is nothing to mess with. Its a strong solvent which attacks many polymers. I stay away from this stuff as far as possible. Its nasty junk, which is why its used to preserve dead bodies. Lol
I'm hoping to hear back from Bliesma before I attempt to glue the chambers back on.
I heard back from Bliesma and they were eager to help with the issue. They gave me the option of sending them the drivers or doing the repair myself. Based on the reply, there's no reason I can't take care of this on my own.
The adhesive they used on the back chamber flange is solvent based and has been chosen based on compatability testing, so they didn't find any problems with the fumes affecting other parts. It was mentioned the nickel plated surface of the motor is a challenge in terms of adhesion, just like I suspected.
Based on this, I'm going to use a solvent based rubberized contact cement which is commonly used in speaker repair to glue dust caps and surrounds. They specify a German brand UHU product of similar characteristics, which is similar to what I'll use. I was given detailed instructions on how to do this and it was roughly what I intended to do to start with, so I'm confident it will work out ok. They also said my repair won't affect my warranty.
I'll keep you guys updated and let you know how it goes, but I don't foresee any issues. Should be a very straight forward fix based on everything I've learned so far.
The adhesive they used on the back chamber flange is solvent based and has been chosen based on compatability testing, so they didn't find any problems with the fumes affecting other parts. It was mentioned the nickel plated surface of the motor is a challenge in terms of adhesion, just like I suspected.
Based on this, I'm going to use a solvent based rubberized contact cement which is commonly used in speaker repair to glue dust caps and surrounds. They specify a German brand UHU product of similar characteristics, which is similar to what I'll use. I was given detailed instructions on how to do this and it was roughly what I intended to do to start with, so I'm confident it will work out ok. They also said my repair won't affect my warranty.
I'll keep you guys updated and let you know how it goes, but I don't foresee any issues. Should be a very straight forward fix based on everything I've learned so far.
I've been doing some adhesive tests on some nickel plated items and a piece of machined cast Alu I have floating around. It looks like the solvent based glue and the RTV are equally acceptable. The RTV has the edge as far as adhesion strength goes and is better at sticking to the nickel plate. Both will work ok, but I'm leaning towards the RTV, as its more flexible and allows for easier manipulation before it sets up. It also makes disassembly easier, despite adhering better.
I've decided to use the RTV, as it sticks the best to the plated surface of the motor. One issue I discovered with the back chamber is the flange being cast unevenly. There is a slight wobble with the flange test fitted to the motor. This may have contributed to the weak adhesive bond, as the contact cement needs to be sufficiently compressed for best adhesion.
That definitely makes your choice of gap-filling RTV the right choice.
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