It is a PVA very similar to Visaton LTS50. They dry without getting tsiff. Repurpoed from crafting. https://www.t-linespeakers.org/design/tweeks.html
dave
dave
It’s an adhesive that should never be painted on to speaker cones. If the cone driver you bought doesn’t perform like you want, you’ve chosen the wrong driver,…..return it……don’t paint it.
Here’s the thing fellas…..so mid domes start becoming directional and beaming around 4k……where we hand it off to a tweeter that‘s Omni at that frequency and then starts to beam around 7k…….thats not great IMO. I’m starting to rethink the crossover points on a three way.……like 1” dome from 1.5 to 8k and then handoff to a ribbon. Run a 180mm midwoofer up to meet the dome or a pair with a .5 network on the lower midwoofer.
I bring this up because there’s something special to my ears about mids coming from a large cone…..the sound warm, full, and natural. Choose the right cone material and they’re also very articulate…..the speaker sounds balanced. Directivity to the side, the B&C 8pe21 is still the best midrange driver I’ve ever heard……I’ve used it up to 3k in reasonably treated rooms and the beaming is a non issue. Even though it’s marketed as an 8” driver, the surround in wide and the single ridge cast into the cone makes it behave more like a 6.
I bring this up because there’s something special to my ears about mids coming from a large cone…..the sound warm, full, and natural. Choose the right cone material and they’re also very articulate…..the speaker sounds balanced. Directivity to the side, the B&C 8pe21 is still the best midrange driver I’ve ever heard……I’ve used it up to 3k in reasonably treated rooms and the beaming is a non issue. Even though it’s marketed as an 8” driver, the surround in wide and the single ridge cast into the cone makes it behave more like a 6.
I would STONGLY urge those participating in this thread to pick up an 8pe21 or pair. Box em up quick and dirty and tune them to 100hz……no parts let ‘em play full range.……there’s literally no breakup and the rolloff is super smooth and nearly perfect 3rd order acoustic. Just listen for a few days and you might rethink the whole dome mid thing.
What about the self-empowering diy spirit?
There is the risk of failure, of course.
But you could start with a cheap driver.
I would call that 'The Tannoy 15" dual-concentric effect' > very nice, clear and engaging sound 🙂
That's why I cross lower - it's obvious 😎
1" from 1,8-2kHz is already very good. Acoustical centers 8cm apart. When you choose T25A as tweeter you have the widest directivity available and piston behaviour at 20kHz.
Ribbon ... you forgot about vertical?
@IamJF
Then the mid becomes a peaking driver…….personally as an engineer I’ve heard enough of these to know they are amazing for monitoring revealing the smallest details and phase problems……but I also know that for listening enjoyment, they’re overly critical and fatiguing…..countless great songs and classic albums are unlistenable. This is why the 2way bookshelf speaker has remained so popular……mix up everything from 1-4khz between two drivers and all of the baked in ugly of a recording sounds ok now.
You’ll have to excuse me for being an old creature of habit and practical experience……it has thickened my skull and change doesn’t come easily. Give me that large format wide band driver of paper and everything sounds right in the world.…sometimes a warm blanket can be personal treasure in the moment…..there’s some Zen in there. Of course I completely respect your approach…..listening pleasures can be as stark as favorite colors….who’s to say orange is better than blue?
As for vertical, I’m a sit down and enjoy kinda listener…..give me a vertical listening window at 3 yards of 20” and I’m happy.
Then the mid becomes a peaking driver…….personally as an engineer I’ve heard enough of these to know they are amazing for monitoring revealing the smallest details and phase problems……but I also know that for listening enjoyment, they’re overly critical and fatiguing…..countless great songs and classic albums are unlistenable. This is why the 2way bookshelf speaker has remained so popular……mix up everything from 1-4khz between two drivers and all of the baked in ugly of a recording sounds ok now.
You’ll have to excuse me for being an old creature of habit and practical experience……it has thickened my skull and change doesn’t come easily. Give me that large format wide band driver of paper and everything sounds right in the world.…sometimes a warm blanket can be personal treasure in the moment…..there’s some Zen in there. Of course I completely respect your approach…..listening pleasures can be as stark as favorite colors….who’s to say orange is better than blue?
As for vertical, I’m a sit down and enjoy kinda listener…..give me a vertical listening window at 3 yards of 20” and I’m happy.
The midrange of my main speakers comes from a vertical array of 6x 5.5" drivers from 700Hz to 5Khz
so I have NO crossover issues going-on in the mid band. It creates a nice midrange coherence 🙂
so I have NO crossover issues going-on in the mid band. It creates a nice midrange coherence 🙂
you can also do it with a 2inch compression driver , 500 to 5K is not out of reach with a lot of them ..
That's more or less the sound you are searching with a 3" dome but without horn and wide radiation. And VERY low THD.
Drivers like the ring membrane B&C and BMS midrange go down easily to 500Hz BUT - you need a big horn for that. Distance to tweeter will be HUGE, also depht differences etc.
Interesting logic. I have a Toyota Highlander but I need a trailer hitch. Should I sell my car and buy a new one with a trailer hitch? I was thinking I would just mod my car by adding a trailer hitch. Or does your logic apply only to speakers?
A lot of the choice regarding these options will come down-to the SPL quantity wanted/expected from your speakers.
PS.
When horns are used phase coherence at C/O frequency can very often require a 180 degree change in phase wiring.
If you’re going to advocate for cone treatment, AT LEAST take away the random application and instruct folks on a visual constructive approach. Install the driver on a suitable baffle and place it facing towards the ceiling. This can only be done with drivers with a sealed dust cap of course…..phase plugs are out. Add a small amount of dry fine silica sand to the cone and play the driver through tones and watch the sand. Take note of the frequencies that create chaotic behavior as opposed to those that produce patterned dispersion of the sand…..those frequencies are the ones you want to attempt to dampen with your cone smearing stuff…..and if nothing changed after the shmear?…..you know you’ve done nothing productive with your time. But if you’ve been lucky enough to reduce the passband of the chaos?……post the video!…..folks will be amazed at what you’ve actually accomplished.
But the frequencies which form patterns are the ones that show resonances. So it's the exact opposite of what you want to dampen!
If you do that sand test, be aware that the sand can easily get in in the air gap, the tiny grain jumps around like a bunch of fleas.
I forgot to mention that this method only works on flat membranes because in a cone the sand stays mostly close to the dustcap and on domes it scatters neatly around the driver. I'm also against the gravity but it's the law.
I'm generally not that fond of applying random mods to drivers. There are reasons to do that though. Yes, there are tons of drivers out there that might fit your profile better. But that doesn't change that you have to spend more money, lose money on the drivers you realize didn't perform fully to your expectation. Be it postage, used not returnable etc, and if you repeat that 2-3 times, you've spent probably more on try & return them than they are initially worth. What about the drivers you already have lying around? And there are some drivers so specialized there are no alternatives. Or you've got some drivers for a that good price you couldn't say no (and no returns possible). To me, that means, modifying drivers is sometimes not something that makes sense (esp if you are just concentrate on one single type of modification). But in other cases you can bring a cheap driver to exceptionally great performance. Or fix a flaw in a driver for a very cheap price. Don't misunderstand me there, a driver is only as good as you are using it but just getting another driver is often just not an option.
Or in short: Modding can be a great way to improve drivers. If you apply the same mod to EVERY driver, then you are maybe overlooking something.
Maybe ITT middome, after 50+ years is still in top 3 of best middome ever made?
A good friend gave me one several years ago. It was in MINT condition. To young I was and didnt realize some day dust would get to it. Well.
Here some quick nearfield measurements with Umik1, wire held with hand to the posts etc. My setup is not calibrated....
To my ears it sounds VERY good with no filter applied at all! Not light either. Tips the scale at 1.6 kg.
Some photos:
A good friend gave me one several years ago. It was in MINT condition. To young I was and didnt realize some day dust would get to it. Well.
Here some quick nearfield measurements with Umik1, wire held with hand to the posts etc. My setup is not calibrated....
To my ears it sounds VERY good with no filter applied at all! Not light either. Tips the scale at 1.6 kg.
Some photos:
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I can confirm it's an excellent driver - still, even after that many years!
That's the problem with vintage drivers, their performance depends strongly on the condition it's in. I don't mind that much about optics but there are tons of drivers in extremely poor condition and the seller still expects you to pay for more than mint condition ones. I'm very, very careful when buying vintage drivers. Not because they are bad but most of them have been handled really badly, stored in catastrophic enviroment or have been abused horribly. It's worth remembering what the average amp back then put out and how modern drivers often do not sound better but are able to cope with much more power and abuse.
I completely agree. Who knows if stuff have been kept for a decade in environment with both too high humidity, frost etc.
Some people think they sit on a gold ore. Worse still, if they no nothing of speakers, they may end destroying the driver in case the ship it without double layer box….should be able to be dropped on corner from 1 meter distance is my take.
I find it fascinating they could make stuff so good back then. Even going to the moon with compute power less than we can even imagine possibly. This is not meaning to provoke, because indeed we as DIY’ers have abundance of stuff available. But maybe to tease a bit if some is lurking.
@mayhem13: You tried the 8pe21 in closed cabinet? If yes then what minimum volume have you tried?
Some people think they sit on a gold ore. Worse still, if they no nothing of speakers, they may end destroying the driver in case the ship it without double layer box….should be able to be dropped on corner from 1 meter distance is my take.
I find it fascinating they could make stuff so good back then. Even going to the moon with compute power less than we can even imagine possibly. This is not meaning to provoke, because indeed we as DIY’ers have abundance of stuff available. But maybe to tease a bit if some is lurking.
@mayhem13: You tried the 8pe21 in closed cabinet? If yes then what minimum volume have you tried?