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Hey people....
I have a pair of mint Electro-Voice SP12b full range 12" drivers that I'd like to use in an open baffle design similar to the one included in the pic. I've decided to augment the frequencies above 10 000 hz with a supertweeter and I'm looking for some recommendations.
Ribbon? Horn? Old school paper cone? What type of tweeter would blend well with large full range drivers?
Any advice appreciated....
Wxxy
Follow Ups:
My Phy-hp 12" are a perfect match with Fostex t500a mk2(in the original open baffle)more linear a smooth them with the original Fostex fe208es-r .
Regards João
Other than the obvious lack of performance in the upper frequency range, what do you want to accomplish? This is the main question.
If you're doing an open baffle, you're going to have "room-filling" sound with very wide dispersion at low to mid frequencies and a large amount of ambient sound, so it would make sense to compliment that with a wide dispersion tweeter, or maybe even multiple tweeters facing different directions.
While I'm a big fan of the E-V T350, I don't think it's the answer for this design, unless you plan to remain pretty much on axis and don't care what the other people at the party hear. ;)
And let's be frank: No 12" cone driver is good up to 10K for hi-fi. Too much mass. (I'd also say too directional, but you're doing an open baffle, so that might not be an issue.) It's a bit like trying to run a 1" tweeter down to 500 Hz.
So, the question is how do you envision the sound field in the room, and where do you want it to sound great? THEN you can choose your tweeters. (I'd also cross to them more around 3KHz than 10KHz. Better yet, get a midrange driver, too. And maybe a sub.)
My main goal is to fill in the frequencies where the main drivers start to roll off...which according to measurement charts I've seen online is somewhere around 10 000 hz.
I'm not going to add a midrange or cross it over at 3000 hz because the whole idea (for me) is to run the main driver full range (no x-over) and fill in the ultra highs with a super-tweeter.
The EV-T350 is interesting, but the prices are beyond what I want to spend for this experiment. I realize this project may not be considered the highest of fi, but I've got a modern set of hi-fi speakers (ProAc) and I'm wanting to try something radically different.
Waxxy
8 ohm, but if 94dB should be very close to your 12's.
Maybe buy 4 to play around with in case they are lower than 94dB?
Read down the comments about shorting with a resistor and using a cap to cut off LF's.
I'd start with a 2MF cap which should put you @ around 10K Hz.
The higher the cap value the lower the tweeter will go and visa versa.
Of course you can also try them without a cap.
Very cool...thanks! At that price, I'd be stupid not to try them!
Waxxy
Briggs used an upward facing tweeter with his open baffle.
ray
...and I've got a tidbit to add. The Electro-Voice SP12b is the 16 ohm model...if that makes any difference?
Thanks....
There is always the Fostex FT17H. The price is not as good as it used to be but it is still resonable and it will work with first order crossovers.
Dave
Well, you could go for the new Johnblue Audio "Crystal Horn" tweeters recently announced on 6Moons (use the link below and scroll down a bit). However, when I requested a price quote from the company, I was surprised when they came back with $2680/pair including shipping to the US.
I use the same open baffles and augment my "full-range" driver with the classic Jensen RP-302. It definitely doesn't goes as high as some other tweeters, but if you are over a certain age, you most likely won't hear those upper high-frequencies anyway. What you will hear is the smooth response from the phenolic diaphragm used in the Jensen. It just sounds better and more natural to me than any metal diaphragm tweeter.
Gerry
is the claim to fame with this new tweeter. Sounds like a lot of money for a tweeter that doesn't do anything more than a fostex horn tweeter.
Its not near the quality of even a Fostex t90a
When I was an audiophile and cared too much about sound quality n things like sound stage n vinyl. When I closed my eyes the sound stage disappeared. My theory was that you hear ultra hi frequencies through your eyes :)|)ooop trebles gone :) there it is. One day when they discover this is true you all wont be laughing then.
Are you serious?
lol maybe :) on a more serious note ray P,s contribution I second. Briggs did the best r&d on open baffle and his article is essential reading. I plan to drop over and read it again now. Ever since I read it the first time I have been looking for the drivers that where specially designed for these baffles. I have the woofers so far they are awesome. I have used the je lab baffle on and off for fives years with little success even with km30. You need a large or at least very long room for it to work well. In smaller rooms I think open back boxes might be better. I plan to try this soon for my km 30. I have a nice set of sealed boxes I plan to just cut a large slot out of the rear and damp really well. Briggs drives where something really special when used in this baffle how they where meant to be. Unfortunately they are by a lot of comments I have read very unreliable especially at this age.
Interestingly I have seen many variations of warfedales open baffles of that error come up for sale but never seen them documented.
On thing that is important that nobody seems to agree with me is the driver needs to be filtered at the low end so it does over excurt with the smaller baffles.
I don't think the problem with the Briggs/Warfedale drivers is that they are unreliable. I have a pair of Warfedale W90's at my mother’s house, that get daily use. We have never had a problem with them. The drivers are also beautifully built. I think the main problem is that people try to drive them with big transistor amps, and they were not designed for that, so they blow. It is not the speakers fault, it is the operator.
Dave
Yes interesting article. Note he uses heavy grill cloth to deal with the problem of over excursion. I would use a pair of Rubicons actively biased with 9 volt battery's. If I built another of these baffle types I would definitely go sand filled. I never could stop my solid timber baffles from sounding colored. And also note how important having 2 drivers is to evening up the bass response. Another seemly forgotten part of the Briggs baffle. All so note this and other baffles are not SE amp friendly or most 2a3 0 feedback amp friendly anyway. They need a higher damping factor to succeed. Some of the best sound I got out of mine was was from a seiman's 2000 projector amp which was designed for single speaker open baffle. It employed an el84 SE plate to grid feedback low frequency eq with sub frequency cut via reduced transformer inductance. That little el84 amp or amps gripped my km30's and rock and rolled. With open baffle my purist approach was to my ultimate torment for too long. As briggs said he used a amp with a damping factor of 15 and still eqed the bass. I will be interesting if I can get the km30's ballanced in open back boxes. If I can get them working well I will sell the suckers and buy a pair of radian 950pbs and aria wood mid horns :)
I've heard deep base throght the seat of my pants, so I guess it is possible...
Dave
EV T350 are very nice... I guess a good match too.
Fostex T500mkII do everything the new Crystal Horn, including the 110 db sensitivity, but they go up to 50khz, and the crystal horn only to 26khz... price is a bit lower too but not too much..ja
Even if your hearing doesnt go up to 20khz you can still hear a difference with a response up to 50khz, bass is better and all instruments sound fuller... I could theorize about harmonics, but the case is: it works!
It works even better with response under 20 hz!
Hi waxxy,
EV SP12B with whizzer cone extend to 10KHz all right, but have try to listen to the results? I had the SP12B mounted in OB in a 2 x 4ft. plain panels. They sounded beamming and honking in the mids.
I decided to used them with a low pass 6dB/oct. à 2,5KHz
A plain and simple coil in series. Be careful and make sure you look at inductors coils calculated for 16 ohms impedance.
I used of the shelf tweeters a had in hands a pair of $40 Peerless ones.
It sounded surprisinly very good. I had two pairs of the EV SP12b's at the time, and ran an ad for them. The buyer saw the SP12B's in OB's and wanted to listen to them, he left with the OB's...and he wanted just the raw speakers at first.........
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