[woodsyi]

Jim,

Great job BTW.  What are the pros and cons of adding a supertweeter?

[ashok]

I have added Parts Express horn tweeters to my Omega TS-1 (Fostex 207E) speakers. Here is a link to the tweeters. http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=270-049. These definitely add sparkle and air that I enjoy. Crossover to the tweeter is first-order, implemented using a 2.2uF capacitor for a frequency of approximately 9kHz.

I also have an active crossover in the mix. The output from the preamp is fed to a Marchand XM1 set at 100Hz. The high output is fed to my mains amp which feeds the Omegas/Tweeter combo. The low output is fed to an AV123 ELT SW10 subwoofer plate amp. The plate amp has an adjustable crossover, which I have set at its maximum value of 120Hz.

Further, the TS-1's themselves have been modified with a baffle-step correction circuit.

So there you have it, my "single-driver" setup.

Ashok

Plug: My TS-1s are for sale in the Trading Post.

[jrebman]

Woodsyi,

I don't know, because I have never done it myself.

I don't want to disillusion people here -- while I have a real interest in this subject, and have had 3 different SD systems, I am by no means an expert.

Ashok's post is just the kind of thing I'm hoping will happen here -- we'll all share our experiences and everybody will benefit.

I'm going to start a thread wher folks can describe their systems, and then maybe we'll have more of an idea of where everybody is coming from.

Ashok, thanks for the post.

-- Jim

[TheChairGuy]

Great question woodsyi...one I've thought of for some time 

I appreciate the single driver coherent sound, but not having a true upper frequency response has greatly limited it's appeal to me.  Especially if you listen to vinyl (as we do), you come to appreciate the extended treble response...to not have it robs the music of it's vitality. You likely won't tell much if it's on CD, or from a CD master...but with vinyl, or analog re-masters on DVD-A and SACD it's likely quite noticeable.

I've been thinking about AV123's units for some time - they advocate them for use with speaker systems already incorporating an existing tweeter, or can be used with single driver applications (that is, is the selectable 11 and 15Khz crossover points ideally matched for many/most single drivers).  To me, it seems too high....a selection in the 7Khz or so range would seem to offer a more correct crossover point for a supertweeter to handle in a single driver application.

But 45Khz - whoooaa - that's extension that you can likely feel, if not hear 

http://www.av123.com/products_product.php?section=speakers&product=74.1

Some info from their forum: http://av123forum.com/showthread.php?t=20908&highlight=extended+response+tweeter

[sts9fan]

I wasn't sure if I was allowed to post here because my speakers have a supertweeter.  I love the sound I am getting from these guys.  The ST does not come in until ~12khz

[doug s.]

hi rim,

i am awaiting delivery of a used deqx i picked up; when it arrives, i will try it with some fostex single-driver speakers i recently bought, & a pair of pioneer ribbon supertweeters i bought a coupla years back, when i thought i might be needing the supertweeter thing - these are extremely efficient, & extend flat to ~100khz.  (see my first post to this circle):
http://www.audiocircle.com/index.php?topic=45062.msg403853#msg403853

if you wanna borrow the ribbons, lemme know...

doug s.

[woodsyi]

Sure Doug,

I will take you up on borrowing the ribbon super tweeters.  I assume it comes with a high pass filter?

TCG,

That's some serious super tweeter.  I would like to hear it some time if I get a chance.  I will try douggie's unit to see if I like the sound with supertweeter first.   I think Dmason had something cooked up for the superhemps on another thread.  It may have been in that darkstar thread.  I will have to do some searching when I get some time.   

[Scott F.]

I use one on occasion with my Lowthers. You can definitely hear the difference. With my speakers extending up to 12-14k, the necessity of a ST really comes down to personal preference. Since there is so little information up beyond the 14k range, the average audiophile likely won't miss the super tweeter. 

If you decide to use one, proper implementation is the key. I've listened to other Lowther owners who have tried to implement ribbons above the main driver with extremely steep slopes and lower crossover points. Unfortunately, it doesn't work. You can immediately hear the disconnect of the ribbon. With the PM2A's (minimally), when you do a frequency response graph, you see that it rolls off rather smoothly at a natural -6db slope. In turn, that makes it a natural candidate for the simplest of 1st order crossovers, a single cap (and reversing the polarity). Doing that at a 6db slope per octave, this pushes your crossover point to between 25 and 30k so that you get a flat response.

A lot of the fine tuning (for me anyway) is done by ear. Once I found a starting point, I kept swapping cap values until I could no longer hear the peaks at the XO point yet I get the benefit of the upper end extension.

I've not heard one used in conjunction with the Fostex's commonly used in the Voight Pipes. It would be interesting to measure those drivers to see where (and how) they drop off.

Although not a single driver, I'm going through this same process right now with my Altec A7's. The horns cover from 500hz to the point where they drop off around 8-10k. I'm pretty close to getting there but I think I'll end up having to buy a decent super tweeter. The inexpensive ones I have here tend to have a timbre mismatch.

[JLM]

A decent extended range driver shouldn't really need a supertweeter.  The "dangers" of adding one could include:

1. Producing a "tipped up" sound as most single driver speakers are somewhat bass weak already.

2. Losing the purist single driver advantages (point source coherency, active design dynamics).

3. Adding the evil power robbing/phase shifting crossover.


IMO best to put the money into a better driver to start with.  (There's precious little place for a poor driver to hide in a single driver speaker.)

[SET Man]

A decent extended range driver shouldn't really need a supertweeter.  The "dangers" of adding one could include:

Hey!

   Hmmm.... I have no idea that there is dangers of adding supertweeters. Maybe to my cat and dog... but they seem fine and my cat usually hang out with me while I'm listening to music. Yes, I agreed with you that a better main driver is a good idea but even with that they don't actually go well beyond 20k much.

1. Producing a "tipped up" sound as most single driver speakers are somewhat bass weak already.

   Well, to me this is false. If you matched them well, xover and SPL wise you should not hear them as "tipped up" to the overall sound. And with that you hardly notice the supertweeter at all.

Losing the purist single driver advantages (point source coherency, active design dynamics).

    This I agreed somewhat with you here. To purist.  Yes, I was a bit hesitated at first about adding them to my main. But the Fostex FT17H are inexpensive so I gave them a try. And you know what the overall sound is better now.... and the whole thing sound even more dynamic to me.

3. Adding the evil power robbing/phase shifting crossover.

   Well, remember that you are only adding xover to the supertweeters not the main driver. So, the main still the same. As for the power robbing xover part...  in my case only a single capacitor (0.47uf) is used and with high frequency only use very small amount of power the power loss is negligent. I do agree a bit with you on the phase shift there but since the superstweeter is use a very high frequency point with 1st order xover I don't think that is matter much.

   Anyway, I ain't no speaker designer but that is what I've experienced with adding supertweeters to my own system. So, I could be wrong here if so any expert could correct me. But I won't be taking out my Fostex FT17H out of my system for sure. And I do encourged others to try this with their SD system, especially if you have SACD and turntable vinyl play back and see if you like it.

Take care,
Buddy

[woodsyi]

Great informations.  I have the 1st generation superhemps.  What caps are people using for 1st order highpass?  Anyone figured out the roll off point on the hemp drivers?

[doug s.]

hi rim,

no, i do not have a passive x-over.  you can either use a passive cap like buddy is doing (easy to find info on the web, on which walues give which x-over points), or go active.  i am planning to go active when i try them, & drive them w/a separate amp, or my akai m8 tapedeck derived set tube monoblocks...  i may actually have some cheap poly caps i bought, but never used, to high-pass them at 10khz, i would need to see if i can find them...

doug s.

Sure Doug,

I will take you up on borrowing the ribbon super tweeters.  I assume it comes with a high pass filter?

TCG,

That's some serious super tweeter.  I would like to hear it some time if I get a chance.  I will try douggie's unit to see if I like the sound with supertweeter first.   I think Dmason had something cooked up for the superhemps on another thread.  It may have been in that darkstar thread.  I will have to do some searching when I get some time.   

[doug s.]

rim, omega quotes 37hz-18khz as the frequency response; you could query them as to the -3db specs.  also, don't you own computer software that allows you to measure frequency response?  you could hook it up & measure...  besides the ivie rta & pink noise generator i have, that i now need, since i am gonna be hooking up different speakers, i also have a 12 band graphic equalizer w/pink noise generator that i could lend you.  this would also give an idea of roll off point...

doug s.

Great informations.  I have the 1st generation superhemps.  What caps are people using for 1st order highpass?  Anyone figured out the roll off point on the hemp drivers?

[ashok]

I am using ICW Clarity caps, bought from DIY cable. I picked a value of 2.2uF, and this gives a cutoff frequency of 1/2/pi/R/C = 9.04kHz. The tweeter is a nominal 8 ohm impedance.

The Fostex 207E still gets the full range signal. I do not find that the sound is tipped up in any way by adding the tweeter. But please note that this observation is purely by ear, and not by means of any scientific measurement of the response of the speaker system.

Also, I have added a baffle-step correction circuit to my Fostex drivers. The BSC helps compensate for the loss in volume of the lower frequencies due to the finite baffle size of the speaker enclosure. The second modification is the phase plug in the dust cap. Both these mods, to my ear at least, produce a very smooth and relaxing sound that I like a lot. Adding the tweeter as high-frequency augmentation adds just the right amount of sparkle (for me at least), without tipping up the response in any way.

I guess the trick is to try the tweeter, and with many different capacitor values, till you find something that you like. The parts express tweeter I am using is $9.25 each. The ICW caps are about $1.75 each. Not too much of a financial outlay.

Ashok

[JLM]

Buddy,

I was trying to write "tongue in cheek", but the purist in me still resists adding a sub (not needed with my Bob Brines FTA-2000s) or supertweeter (as Bob says, the need is probably more a question of your age than anything else). 

IMO the meat/heart of the music is between 40 - 8,000 Hz (8 octaves).  50 years ago or so designers were happy for the most part to call 80 - 8,000 Hz (7 octaves) full range.  If you look into vintage speakers, few went below 40 Hz and most mid/tweeters were front loaded horns.  (Both done to keep efficiency up with the small amps that were about the only thing available in their day.)

Putting in another plug for Brines:  he offers plans, pre-cut cabinet panels, assembled cabinets, or fully assembled speakers all at very reasonable prices.  So for as little as $300 for the parts you could glue up and veneer a very nice 37 - 20,000 Hz, 94 dB/w/m, 8 ohm pair of floorstanding speakers (less than what many pay for just speaker stands).

The supertweeter question also reminds me of designs that use a simple tweeter/cap design, like the smaller Reference 3A models, but don't promote themselves as single driver designs.  So there is a potentially "slippery slope" here. 

It's ironic to me that some would spend more on the supertweeter (to fill in one octave) than the original driver (that's covering the heart of the music).

Your supertweeter application doesn't seem to fall into any of these "practical" pitfalls.

[GBB]

I am using ICW Clarity caps, bought from DIY cable. I picked a value of 2.2uF, and this gives a cutoff frequency of 1/2/pi/R/C = 9.04kHz. The tweeter is a nominal 8 ohm impedance.

This simple calculation of the crossover cap may not give you the best result.  Bruce Edgar (of Edgarhorn fame) recommendeds adding a super tweeter to fill in above 10khz with his horns.  Among the tweeters that he recommends are the Fane 5022 (a bullet tweeter similar to the old JBLs) or the Fostex tweeters (T90, T925, T900, etc.).  For the Fane he finds the best integration with a 1uf capacitor and with the Fostex he gets the best results with a 1.5uf capacitor.  All of these are nominally 8ohm speakers.

So I'd suggest playing around with the crossover cap before making your mind up.  Too big a cap and you might get more overlap than you want leading to a frequency bump in the 5-10khz range.  Too small a cap and you won't get much benefit.  Find the right value and it will sound just right.

---Gary

[IronLion]

I didn't think about installing a supertweeter into my single-drive speaker, the folks at Zu did it for me.  I'm actually going to have the network on my Tones reworked for smoother treble response, as the supertweeter right now could be smoother, especially on certain recordings. 

[ashok]

I am using ICW Clarity caps, bought from DIY cable. I picked a value of 2.2uF, and this gives a cutoff frequency of 1/2/pi/R/C = 9.04kHz. The tweeter is a nominal 8 ohm impedance.

So I'd suggest playing around with the crossover cap before making your mind up.  Too big a cap and you might get more overlap than you want leading to a frequency bump in the 5-10khz range.  Too small a cap and you won't get much benefit.  Find the right value and it will sound just right.

I agree with you. As I did say in my previous post, try different capacitor values till you find one that you like the best. The 2.2uF sounds good in my setup, and I went with it.

Ashok

[GBB]

I agree with you. As I did say in my previous post, try different capacitor values till you find one that you like the best. The 2.2uF sounds good in my setup, and I went with it.

Ashok,
I think we are almost in complete agreement.  The only quibble I have with your post is using the simple formula 1/2/pi/R/C to calculate the transition point from the full range driver to the tweeter.  I've seen too many folks blindly follow that formula and not use their ears to optimize the crossover cap value.  And then they conclude that they don't like the sound of the supertweeter. 
So I just wanted to reinforce your point that you must experiment with the crossover cap and it often will sound better with a smaller cap than simple calculations might suggest

---Gary

[FredT300B]

I've had a few single driver speakers in the past using Fostex and Audio Nirvana drivers. I didn't feel the need for a supertweeter with any, but I did install one facing backward in a pair of Fostex FE167E Voigt pipes only because I already had a pair on hand, and they did add a bit of ambience and sparkle to the speakers sound.

My current SD speakers are bass reflex enclosures housing Pioneer 8" full range speakers. MCM had the Pioneers on sale for $25 each, and sale prices often determine which drivers I will try next. The Pioneers are very different from Fostex and Lowther drivers; at 90dB they are no more sensitive than most woofers, but they have very good bass response in a BR enclosure. Their achilles heel is in the treble - it rolls off steeply above about 10khz, so it is audibly missing when the Pioneer driver is used without a supertweeter.

Since these are extreme budget speakers I didn't want to spend much money on tweeters, so I got a pair of the 5/8" Dayton neo domes for $4.60ea. Their 90dB sensitivity would make then a poor match for Fostex and Lowther drivers but a good match for the Pioneers. Crossed over with a single 1uF cap they do exaclty what I wanted: they provide that "air" that was missing with only the Pioneers and they don't make themselves obvious to the extent that you would know there's a tweeter in the speaker. Total cost including the sheet of baltic birch ply was about $100 for the pair.

http://fredt300b.smugmug.com/gallery/132721#185516928