27tbfc/g (h1212)

[oneoldude]

Looking at the Seas data sheet on the H1212 makes me think it could well be used at very low freqs with a steep filter. Any suggestions on how low it can go with 4 pole or 8 pole filters?

Intended use is HT. Anything to watch out for, like headroom?

Any tweaks reccomended for it re the phase shield etc.?

Are there any good bucking magnets available for it for HT use?

I am thinking of using it with a pair of RS180's in an MTM. Has anyone used it this way? Advice?

[GrahamT]

Hi OldDude,

I believe that Jon is working on modifying the Modula MTM for the H1212. That is an MTM with the RS180s.

[oneoldude]

Thanks for the heads up.

In the meantime, re the H1212:

Any suggestions on how low it can go with 4 pole or 8 pole filters?

Intended use is HT. Anything to watch out for, like headroom?

Any tweaks reccomended for it re the phase shield etc.?

Are there any good bucking magnets available for it for HT use?

Advice?

[JonMarsh]

It's LF capabilities are similar to the 27TDFC and Millenium Excel. For all of these, for a standard LR4 crossover, I'd recommend 1400 Hz or thereabouts (no lower); for the quasi-LR8 CE type network, 1200-1250 should be OK. Driver spacing, panel layout, and midwoofer capability are of course big factors.

The MTM modula crossover with the H1212 will be VERY similar to the existing one, I only expect a tweak of the HF voicing, and though the Fs zoble may be modified slightly, in practice it wouldn't be necessary, I think.

I also plan to investigate removing the phase shield in the H1212 if possible- I haven't had time yet to look closely at the ones I received, and I'm still in the process of settup up the new PC I built for Praxis.


~Jon

[oneoldude]

Jon,

Thanks for the unambiguous reply. Direct answers to questions are greatly appreciated. Your response is exactly what I needed to know. Thanks a heap. :T

One last question though. If I can find bucking magnets for the tweeter will their use appreciably change the fundamental specs of the tweeter? ;x(

[JonMarsh]

It won't change the resonance frequency, and hopefully shouldn't change the BL product significantly. I wouldn't expect to see any measurable difference.

~Jon

[oneoldude]

Jon,

Thanks again.

[cjd]

I've used the TDFC and TDFC/TV interchangeably with no significant differences beyond what might be expected in normal driver-to-driver comparisons. However, I have only done this in crossovers at 2100Hz.

Of bigger concern is the fact that a bucking magnet would require you remove that chamber. Comparing the TDFC variants, you may note that output between 1kHz and 2kHz does not match between the two - enough that you may find a crossover needs to be tweaked for the shielded version.

Just some food for thought.

C

[JonMarsh]

Very good points Chris- implementing a bucking magnet with a chambered tweeter is not a trivial proposition- maybe not even a feasible one.

[capslock]

I have the nasty feeling you cannot get to the Seas phase shield without
either ripping the grille from its glue joint or prying the surround from the alignment thingie.

The easiest way might be dipping the grille into acetone...

[EdL]

Seas sources (US)

In my virtual shopping trips, I find 3 sources for Seas drivers:

Madisound
Zalytron
Brass & Granite Audio

I'm going to get on board here with a pair of H1212.
Have I overlooked any other sources for them?
Does anyone have comments about those suppliers they would like to share?

[Brian Bunge]

There's also Meniscus: www.meniscusaudio.com

[cjd]

John at Madisound is a pretty good guy. I'm sure the same can be said elsewhere, but I actually talked to the guy. They've kicked in goodies for the local DIY events, etc. etc. Plus Madison is a great town and local-ish. I get my stuff overnight with standard ground shipping. ('cause I live close enough). So, I can highly recommend them.

C

[GrahamT]

Also www.Solen.ca , I've ordered from them a couple of times. Once they went out of their way to help me out with an order.

[JonMarsh]

I've worked with Josh and some of the other guys at Madisound, and they're the ones that get my Seas and Peerless business. Solen is great if you're in Canada; I've bought from them, too, but it's a bit of hassle from the US, though not to bad as long as you use the post office for the brokering.

~Jon

[Armand]

Hello all. Do you think the H1212 will work in a design using a 1st order xover at 2.5K or would there be too much lower frequency energy for this tweeter? If not, any recommendations on a SEAS tweeter that will work in this configuration? Do you find the H1212 tweeter to reduce the typical "metalic" ringing I hear from older metal dome designs? Thanks for any info you can provide.

[JonMarsh]

Much of the "metallic ringing" heard in older metal dome tweeters is due to their phase diffuser designs, which act like Helmholtz resonators at high frequencies, not just the dome. Good example is the Vifa aluminum tweeters and the MB Quart Titanium tweeter. Pull the diffuser off an MB quart 1", and they sound pretty good (standard mod for custom version of MB Quart done for Avalon, which I've also used- both the hand modified veresion and the custom version).

Note that one of the better aluminum dome tweeters I've heard or measured is the Hales Transcendence, which is a custom Vifa OEM'd for Hales, and not a diffuser in site. Focals sound better without them, too.

Still, it's a good idea to look at the extended tweeter response and the peak of the HF resonance once the diffuser is removed. Unfortunately, removing it for an H1212 is pretty much impossible- the front plate, surround, and dome/VC is an integral assembly.

What these tweeters DON'T like, in genereal, is mediocre solid state electronics, either source or amplification. They tend to have the kind of aural problems which these tweeters will ruthlessly unmask- just like the Focal TC120's I'm rather fond of. Pair with good sources for good results.

Last, a 1st order crossover at 2.5 kHz may be problematic- depends on what your expectations are for SPL. -3 dB at 2500 Hz is -9 dB at 1250 Hz, -14 dB at 625 Hz. At more moderate SPL, probably OK. BTW, what are you going to run up to 2500 Hz with a 1st order crossover- it should be clean to two octaves beyond... I don't know of any cone driver I'd do that with. Is this a three way with dome mid?

Last, what are you going to do about the inherent off axis lobe in the power resonse of a 1st order network? I've always found that something of an objectional coloration, especially the difference between sitting and standing response, as well as the net power response. The only way I know of to remedy that in room is a staggered vertical MTM as Dunlavy used.

If you think the H1212 will be too "metallic" in your system, the 27TBC is the fall back position at low cost, the Millenium Excel if you've got bucks to burn. It's just that the Excel doesn't seem to have any better distortion or LF output in actual measurement. But it's built very nice.

Good luck and have fun with your system, whatever you decide on.

~Jon

[Armand]

Hi Jon and thanks for the response. While I'm not an expert on the subject, I know enough to be dangerous. ;}

The speakers are modified Spica TC-50's. The x-over components were all upraded and tweeked to accomodate a Seas H883 metal dome, re-wired with Cardas wire, the replaced woofer (according to th modifier) is a higher performance version of the original Audax driver and doped with a white Seas doping compound instead of glue like the original. Finally, the cabinets were braced with lead as the weight nearly doubled and rapping the cabs literally hurts your knuckles.

The improvements weren't subtle. While the speakers retain that holographic soundstage and imaging the Spica's are know for, they are also much more open with the ability to play at greater SPL than the original. They are crossed over at 100hz as I use them with Kinergetics 2x10 subs on a dedicated stand made by Kinergetics.

The only problem was my objection to a slight metalic sound even with the phase cover removed. (Which come off easily with a jewlers screwdriver, btw). So I replaced it with a soft dome 27TFFC which I liked alot better. Much smoother but not quite as detailed which was OK. So now I'm reading about the H1212 and am thinking if I can get the detail back without the steel, I'd try a pair.

As far as the woofer is concerned, I believe Jon Bau used a 4th-order Bessel for rapid rolloff. So does this change things any? Thanks again

[oneoldude]

Jon,

You said re the H1212:

It's LF capabilities are similar to the 27TDFC and Millenium Excel. For all of these, for a standard LR4 crossover, I'd recommend 1400 Hz or thereabouts (no lower); for the quasi-LR8 CE type network, 1200-1250 should be OK.

~Jon

So I ask, for this family of drivers what is the max practical SPL you would suggest at crossover for the for each of the examples you give. That is, LR4 @ 1.4 kHz and q-LR8 CE @ 1.2-1.250 kHz?

Also, since both networks are down 6 db at crossover then in the T passband the max practical SPL will be the respective numbers you give for each example plus 6 db. Right?

I am trying to get a handle on the headroom available for an average listening level of say 86 db SPL.

[JonMarsh]

Sounds like he was using an asymmetrical crossover- that can be an interesting technique to solve phase issues at the crossover frequency, and transfer part of the workload from one driver to the other.

IMO, the H1212 would be up to the job as regards it's low end extension- as long as it isn't an "experiment" that would break the bank for you, why not? The H1212 does seem to have a cleaner waterfall plot, so if you don't hit it wtih stuff up above 30 kHz, will probably be OK. I suspect that combining it with a peaky moving coil cartridge could lead to IM problems; you wouldn't hear the breakup frequency per se, but it might fold down to the audible range. They appear fairly compatible in other charcteristics (general impedance and sensitivity).

~Jon

[Armand]

I just received the H1212's in the mail. The phase diffusors are definately more robust than the H883's. I don't think I'm going to get these off with a jewlers screwdiver, that's for sure! Since I have to solder some heavy guage Cardas on these tiny posts, what kind of solder do you guys recommend?

Also, I now remember that the original modifier covered the plastic chamber of the H883's with putty to keep it from resonating. What do you think of this idea?

[oneoldude]

When I got my H1212 drivers I found that the rear of the chamber has a rather tinny, scratchy quality to the sound it makes if tapped with a fingernail. I did not like the possiblity that the back of the chamber might resonate and decided to do something about it.

I filled all the depressions on outside of the back of the chamber with GEM-TAC glue made by Beacon. You can buy it at sewing centers and hobby centers. It is used to glue rhinestons, glitter, etc. to cloth.

It, is very thick, goes on white like Elmer's and dries crystal clear. When dry it is a flexible, clear, rubbery substance. It seems to work nicely to damp the backside of the chamber. Nice part about it is that it is water based and can be cleaned up with water before it dries. Once dry however it seems to be virtually waterproof.

BTW, if you put it on real thick, be prepared to wait several days for it to dry. You will know it is dry when it is completely crystal clear.

Now whether this helps the H1212 or not I do not know. I think it is like chicken soup. It can't hurt.

This is neat stuff and might have other uses for damping. It can be thinned with water and painted on. Hmmm.

[morbo]

I have done this type of thing with several drivers, using blutak on the basket and to dampen resonances, especially in the cheaper, steel framed fullrange drivers like the TB 871. One thing I always wondered is how much it affects the heat dissipation of the driver, since I assume the entire driver is taken into account when designers model a driver's thermal behaviour.

[oneoldude]

I doubt there is much to worry about with the H1212 tweeter. The entire flange, frame and chamber are made of injected plastic that I am sure does not act much like a heat sink.

Mids and woofers might be another thing altogether. However, most of the good ones are vented and the airflow is what cools the VC.

Also, keep in mind that for a damping layer to work well on a flat surface it needs to have the same mass as the item being damped. From what I have seen others do, there is too little damping material to do much good on a W or M frame.

However if you can wedge damping material tightly between surfaces it can damp well by friction losses especially if there is a relative rocking or ringing motion between the parts. One example is the rubber disks placed between the fins on the heads of certain motorcycles. They do stop the fins from ringing.

I have seen a similar thing done with hot glue squeezed into the gap between the magnet's front plate and the basket on the outside of drivers. That seems like it might help some cheap drivers from rocking their magnets. But with high quality drivers with cast baskets I wonder if it would be of any use at all. On the other hand it might be like chicken soup all over again. :lol:

[borderdad]

Tang Band mod

Sorry to break in with a bit of an off thread question but it's in keeping with some of the comments. Anyway. I read about a mod for the Tang Band W4-1052SA using Gemtack glue and a three component add-on (crossover parts) on the positive side. Does this sound like snake oil? I've had four of these for a couple of years and would like to use them. Thanks. Kevin.

Here's the link:Tang Band mod

[Armand]

Thanks for the responses.

The Gem-Tac idea sounds like a project all it's own, but I do have plenty of Blu-Tac around which I'm thinking will do the job.

What type solder might make the job easiest using high gauge cable on these tiny posts? I no longer have the steadiest of hands in my old age. Any soldering tips you can pass along is appreciated.

borderdad: It appears that they have found a location on the cone that is a break-up point and are using the glue to damp it. If that's a paper cone, well, all paper cones should be damped as they all have a nasty break-up. If done right, paper is still one of the fastest, uncolored sounding cone materials to my ears. That's why Wilson still uses them.

[borderdad]

If that's a paper cone, well, all paper cones should be damped as they all have a nasty break-up.

According to Tang Band, this driver has a unique ultra-thin polypropylene cone. Who knows. Maybe I'll try it on a couple and A-B them, see if I can tell the difference.

[oneoldude]

I use pencil style soldering irons and the typical solder used for circuit boards. The solder is quite thin and has a rosin core. Do not use acid core or acid flux for any electronic circuits, including speakers. You can get the right stuff at Radio Shack.

If you want to get slick, you can use solder with some silver content. Some say it "sounds" better. I cannot hear the difference but I use it anyway. I believe it is somewhat stronger than solder with no silver in it at all. I think you can get that at Radio Shack too.

As for large guage wire on a small post, if you are using stranded wire you can make the end smaller so that it is useable. You can untwist the stripped end you are going to use, splay it, cut away enough strands to make the end useable, twist it tight in the same direction it was originally, wrap the now smaller wire to the post for a good mechanical attachment and solder it. Be sure to use enough solder to have it flow past where you cut strands so that the fat part of the wire is fully soldered to the skinny part. If you are using solid wire, you are on your own.

Do not worry that you have somehow changed some magical quality of the wire by making it smaller guage on its end. The end is so short that it will make no difference. Remember you need sufficient heat to get the solder to flow but not so much that you melt the plastic support for the pin or the plastic frame and flange of the H1212. Also be sure nothing moves while the solder is cooling. The completed solder joint should be shiny. If it has a frosty look, do it again because it could be a cold joint and cause problems.

One last thing you should consider is to isolate the pin and wire on all speakers from possible shorts. This can be done with tape or heat shrink tubing. If you use heat shrink, keep in mind that excessive heat may damage the driver.

Good luck.

[Armand]

According to Tang Band, this driver has a unique ultra-thin polypropylene cone. Who knows. Maybe I'll try it on a couple and A-B them, see if I can tell the difference.

That still doesn't mean that it won't have a break-up mode somewhere. Plus, it's interesting to note that they'll perform the mod free of charge if you buy from PE. The measurement so show a slight improvement.

[Armand]

I use pencil style soldering irons and the typical solder used for circuit boards. The solder is quite thin and has a rosin core. Do not use acid core or acid flux for any electronic circuits, including speakers. You can get the right stuff at Radio Shack.

If you want to get slick, you can use solder with some silver content. Some say it "sounds" better. I cannot hear the difference but I use it anyway. I believe it is somewhat stronger than solder with no silver in it at all. I think you can get that at Radio Shack too.

As for large guage wire on a small post, if you are using stranded wire you can make the end smaller so that it is useable. You can untwist the stripped end you are going to use, splay it, cut away enough strands to make the end useable, twist it tight in the same direction it was originally, wrap the now smaller wire to the post for a good mechanical attachment and solder it. Be sure to use enough solder to have it flow past where you cut strands so that the fat part of the wire is fully soldered to the skinny part. If you are using solid wire, you are on your own.

Do not worry that you have somehow changed some magical quality of the wire by making it smaller guage on its end. The end is so short that it will make no difference. Remember you need sufficient heat to get the solder to flow but not so much that you melt the plastic support for the pin or the plastic frame and flange of the H1212. Also be sure nothing moves while the solder is cooling. The completed solder joint should be shiny. If it has a frosty look, do it again because it could be a cold joint and cause problems.

One last thing you should consider is to isolate the pin and wire on all speakers from possible shorts. This can be done with tape or heat shrink tubing. If you use heat shrink, keep in mind that excessive heat may damage the driver.

Good luck.

Thanks for the response and tips oneoldude. I do have some 2% silver solder which I'll use. Your strand cut-down down tip sounds like it would be my best bet.

[dlr]

Additional damping may not be necessary

When I got my H1212 drivers I found that the rear of the chamber has a rather tinny, scratchy quality to the sound it makes if tapped with a fingernail. I did not like the possiblity that the back of the chamber might resonate and decided to do something about it.

Now whether this helps the H1212 or not I do not know. I think it is like chicken soup. It can't hurt.

I've tested a couple of the Seas tweeters sent to me by Mark. Due to this, I've never opened the back, but if the H1212 is like the 27TDC, then it is probably sufficiently damped internally. There will be felt in the chamber as well as a very effective damping foam plug in the pole-piece vent. If someone could measure one of these before and after adding some external damping material, that would be interesting. If it is a benefit it will be readily apparent in any typical measurement as long as the measurement conditions (mic position, start/stop time markers, room ambient noise level) are the same.

I suspect that with this driver it is not going to show much improvement as Seas has some of the best damping in tweeters that I've encountered. Now if the chamber is not fully stuffed, then that would be where I'd be inclined to do something, though this can be destructive if care is not taken. The benefit is that there is additional damping of the internal signal.

dlr

[Armand]

I'm worried that the back wave of the woofer might cause the tweeter chamber to resonate. I've already applied the BT and it's now very well damped. I plan on installing the drivers in a few hours. Anyone want to guess as to how long they'll take to break-in?

I'd really like to take that metal grille off, but I'm weary about damaging those delicate wires coming off the terminals. But those grilles are there for a purpose anyway, so I'll worry about that later when someone figures out how to get them off and tells me that they measure or hear a positive difference. I notice manufacturers like Totem don't take the covers off of their Seas tweeters.

[cjd]

I'm worried that the back wave of the woofer might cause the tweeter chamber to resonate.

Well, hey... that's why Jon is a proponent of building a separate sub-enclosure for the tweeter. It's not just th chamber, but leakage potential around the plastic face-plate. I do the same, for whatever that is worth, but only because I saw the sense in Jon's approach.

C

[Armand]

I agree of course, but these are modified Spica's. If I was building from scratch, I would isolate everything including the xover.

What do you guys use as a gasket material. The original sticky rubber the modifier used is kinda old and I'd rather use something new. Might Blu-Tac work? Thanks for any suggestions.

[GrahamT]

What do you guys use as a gasket material.Thanks for any suggestions.

I like to use closed cell form tape. It comes in many widths and depths and works great IMO.

[Armand]

Thanks. Where can I get some? Might Radio Shack or Ace Hardware have it?

[GrahamT]

You can get closed cell foam tape from Home Depot etc. It's used for sealing door frames. You can probably get something similar from an online source but I'm not certain.

[cjd]

I know Parts Express sells some nice foam for sealing drivers in.

C

[oneoldude]

I really like Jon's build up around the tweeter. It really strengthens the front baffle and the entire system becomes really stiff if you put a brace from the T box to the back of the cabinet.

But I understand from his writings that Jon simply threads the T wiring through some holes in the T box and the holes are not sealed. Am I mistaken about that?

I mention this because if the T is all boxed up but there are open holes to the internal pressures of the W then there is no protection from those W pressures.

[GrahamT]

But I understand from his writings that Jon simply threads the T wiring through some holes in the T box and the holes are not sealed. Am I mistaken about that?

I'm sure he seals the holes with something, but not until after he tests the crossovers. I used clear silicone on my tweeter housings, worked well.

[Armand]

You can get closed cell foam tape from Home Depot etc. It's used for sealing door frames. You can probably get something similar from an online source but I'm not certain.

OK. That's what is on the original tweets so I decided to reuse it.

Well, they're installed and I like what I hear. I'm listening to Clark Terry on Chesky records and his trumpet and the cymbals never sound so smooth. Brushes are very defined without sounding like rain. By comparison, the 27TFFC was slightly ragged and the metal dome H398 more so with a metalic touch. Even the original Spica tweeter (Vifa) wasn't all that smooth.

I don't hear any metalic colorations at all so far. I'm amazed. But we'll see what happens as they break-in.

Thanks for the suggestion with this tweeter. I'm glad I found this place. You guys sure know your stuff. Back to listening!

[GrahamT]

Well, they're installed and I like what I hear... Back to listening!

Glad to hear it.:T

[JonMarsh]

OK. That's what is on the original tweets so I decided to reuse it.

Well, they're installed and I like what I hear. I'm listening to Clark Terry on Chesky records and his trumpet and the cymbals never sound so smooth. Brushes are very defined without sounding like rain. By comparison, the 27TFFC was slightly ragged and the metal dome H398 more so with a metalic touch. Even the original Spica tweeter (Vifa) wasn't all that smooth.

I don't hear any metalic colorations at all so far. I'm amazed. But we'll see what happens as they break-in.

Thanks for the suggestion with this tweeter. I'm glad I found this place. You guys sure know your stuff. Back to listening!

Thanks for the kind words, and glad we have another satisfied "customer"!
:T

Happy listening...