| Nuuk |
OK, we have had many threads about which is the 'best' tweeter but I am looking for something to compliment my Godmans 201 'full-range' drivers and they will only need to work from 6 kHz at minimum.
So, I don't have to worry about how low they will cross over and wondered if, relieved of the lower frequency workload, it would make sense to go for a tweeter that went as high as 30 kHz.
Any comments? |
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| pinkmouse |
| Well, for one classic driver, you really need another. |
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| Nuuk |
Thanks Pinky! ;) I have seen Coles supertweeters on Ebay but didn't realise that they were worth bidding on!
Any idea what they cost and where you buy them new? |
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| pinkmouse |
| I believe Wilmslow stock them. I can't remember exact prices, but they weren't that expensive. |
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| Nuuk |
I can't see anything on Wilmslow's site but I have asked Coles where I can buy them. There have been quite a few on Ebay recently but none at present! :(
Do I understand the Coles site properly? The higher you cross them over, the higher they will go? |
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| pinkmouse |
I haven't played with one for about 5 years, but they were certainly pretty flat out to about 22K where the measurement mic I was using at the time gave up.
It's probably worth keeping your eye on eBay, they do seem to come up quite frequently, but the more I think about it, the more I'm sure they were only about £30 new. |
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| simon5 |
| 6 kHz and up? I'd use a Seas 27TBFC/G or 27TDFC. |
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| phibes |
I don't know how many are still available out there or for that matter what they would be worth now, but perhaps Audax's HD3P may work......
Cheers, |
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| Nuuk |
| quote: | | 6 kHz and up? I'd use a Seas 27TBFC/G or 27TDFC. |
That has been my choice based on the review on Zaph's web site but I wondered if they were optimal as I don't need to go lower than 6 kHz.
| quote: | | I don't know how many are still available out there or for that matter what they would be worth now, but perhaps Audax's HD3P may work...... |
You are right, they are very rarely seen these days and even if they were, I doubt they would go for much less than the original price of around a hundred pounds. :( |
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| Nuuk |
Thanks Sretin,
I was on Falcon's site last night looking at tweeters but didn't scroll down to the 'Other Drivers' section!
Only one problem - the small faceplate as I have already made the baffles! Having said that, I could fit them with a small modification. ;) |
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| badman |
How sensitive are the godmans? I've been crossing a variety of (super) tweeters over at that point or so for quite some time, I find it to be a near optimal XO point in many instances, far enough out of the midband that it's less noticable, not so atrociously high that a good mid can't keep it together.
Best!
Badman |
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| Nuuk |
| quote: | | How sensitive are the godmans? |
I'm not sure - I don't know if anybody has ever found the specifications for the 201's and mine are modified anyway. Listening to them in the OB's I would say that they are fairly high efficiency as they go very loud when driven by 12 volt Gainclones! :) |
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| Lionel |
If compatible with the sensitivity of your full-range drivers :
[/URL]FT17H |
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| Toaster |
| Aurum Cantus G2si? sensitivity is about the same as your 201s and they certainly sound better to me than most domes in terms of delicacy and detail. The only real limitation I've found is that they sound a bit forced sooner then a decent dome like a SEAS or Morel crossed over at the usual 3kHz or so, but crossed over at 6kHz I doubt that would be an issue. Or if you want to go vintage the Decca DK30 or the London are still pretty amazing if you crossover high and don't need too much volume. Expensive though... |
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| Nuuk |
Some good suggestions. The Fostex goes up to 50 kHz so I could entertain any passing bats! ;) I intend to use a spearate amp for the tweeters so the sensitivity needn't be a big issue!
Ribbons I think are out of my price-range at this time. |
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| badman |
| I currently use the fostex FT17H crossed over first order at about 5k. GREAT tweeter, if you don't mind horn dispersion. Their lower sensitivity FT7RP (93dB) is also very good, and very reasonably priced for a ribbon (again, extension up to 40-50k) |
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| MBK |
Actually the horn dispersion should help in this case.
I would first measure your dispersion (off-axis response) vs frequency, and then choose x-o point and what will likely have to be a horn tweeter to match the measured dispersion at chosen x-o. Otherwise you'll have a honk problem, if you plug in a wide dispersion dome into an already severely beaming fullrange at 6 kHz. |
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| Nuuk |
Well, I was up too late last night Googling for the Fostex FT17X and there are many people recommending it. There were a couple of exceptions though, notably Dick Olsher who tried one with his BassZilla and found it made a spitting noise!
That's a good point about the dispersion issue though MJK! I have not encountered it with my present OBs and dome tweeters, but they cross over higher (currently usig a 1.0 uF cap).
The Fostex is my current choice for now although the search goes on. :) |
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| badman |
| quote: | Originally posted by MBK
Actually the horn dispersion should help in this case.
I would first measure your dispersion (off-axis response) vs frequency, and then choose x-o point and what will likely have to be a horn tweeter to match the measured dispersion at chosen x-o. Otherwise you'll have a honk problem, if you plug in a wide dispersion dome into an already severely beaming fullrange at 6 kHz. |
Indeed, which is why I use it. I'm inclined to believe that large transitions in dispersion characteristics are quite disturbing, perhaps it's the transitions that are the biggest bonus about constant directivity speakers? I won't claim to know, but I like the FT17H. |
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| MBK |
Nuuk, Badman,
Fullranges have the problem of unavoidable beaming at HF and therefore suboptimal power response, and of course the advantage of crossoverless coherency. But people have reported good results using supertweeters - maybe above a certain frequency, say 10 kHz, the dispersion issue comes less into play. But it certainly does matter up to 5 - 6 kHz. Nuuk, if you are using dipoles they will have a better polar behavior (more directivity) anyway and you have an added advantage here.
I was toying with the idea of the Fostex for a while, when I had my Diatones with a dome helper tweeter. But frankly the Diatones left alone were already very good, and the system sounded best either by leaving them alone, or by crossing the dome tweeter fairly low, 1600-2500 Hz. Above that things became honky - the ear does notice the "hole" in the off axis response that gets filled up progressively by the helper tweeter. The Fostex would have been an interesting experiment.
FWIW the controlled directivity is one of the main purposes of dipoles, and to some extent of horns as well. Horns have the advantage of better efficiency, with the trade offs of next to impossible implementation in the deep bass, and a maybe too little room interaction to give a "reality" (they are here) feeling to the sound according to some (including Siegfied Linkwitz). Dipoles have the advantage of near perfect control of directivity with lessened, yet still noticeable room interaction, and the trade-off of decreased efficiency in the bass rolloff region. Both types well implemented, especially keeping the x-o's in regions of overlapping and similar directivity, should have a flat power response, and this seems to be a major factor for realism. |
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| Nuuk |
Thanks again MBK. I guess the answer to is to buy a horn tweeter and play around with the crossover point. I seem to have a bit of latitude with the full-range drivers so there's another thing for me to play with!
Another advantage of the OB's is that it is easy to change things around quickly! :)
BTW - is it my imagination or did you post from Hong Kong with your previous post? :xeye: |
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| DeonC |
I second the suggestion of the LCY 100K. My second choice (and the ones I ordered through a group buy for my own Axiom 201s) is the Aurum Cantus G2si.
Enjoy,
Deon |
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| MBK |
Hi Nuuk,
Singapore, not Hong Kong... SE Asia rather than E Asia. But quite close in the time zone (1:20 am here)... Maybe you're confusing me with someone else, because I've always posted from here , at least the past 4 years
;) |
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| Nuuk |
| quote: | | I second the suggestion of the LCY 100K |
Thanks Leon, that's one to put on my Christmas wish list! ;)
As an aside, have you ever compared running your 201's full-range (ie without any crossover) and cut off at say 100 Hz so they are relieved of bass duty? :att'n: |
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| Nuuk |
| MBK - yes I must have have got you confused with somebody else. Given the choice, I would rather be in Singapore than Hong Kong (even at 1:20am)! ;) |
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| DeonC |
Not yet, but then again I have not had the budget lately to play around. :( I do however think that cutting them off is a must. They don't really have the power-handling or Xmax capabilities to do bass. I would say about 70Hz yo 80Hz would be good. The a pair of either the Stryke or the Dayton IB woofers on an open baffle would be a very nice idea. ;) :D
Enjoy,
Deon |
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| Nuuk |
| quote: | | The a pair of either the Stryke or the Dayton IB woofers on an open baffle would be a very nice idea. |
Well, I'm going this way ! ;) |
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| planet10 |
| quote: | Originally posted by MBK
Actually the horn dispersion should help in this case.
I would first measure your dispersion (off-axis response) vs frequency, and then choose x-o point and what will likely have to be a horn tweeter to match the measured dispersion at chosen x-o. Otherwise you'll have a honk problem, if you plug in a wide dispersion dome into an already severely beaming fullrange at 6 kHz. |
I'm late into this thread, but this is pretty much what i was going to say. You want something with controlled diectivity. The Fostex are amoungst the best, and there are even frugal-phile(tm) class Foster tweeters that i have found to do a respectable job.
dave |
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| planet10 |
It is pleasing to find that Coles is still in business :)
The Axiom 201 spec does not include efficiency, but i;d guess 95-96 from the pair i had here.
dave |
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| Nuuk |
| quote: | | The Axiom 201 spec does not include efficiency, but i;d guess 95-96 from the pair i had here. |
I agree Dave! Listening to mine I have always put them around the 95 mark. :) |
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| badman |
I've always been one for NOT NOT NOT NOT NOT padding down drivers. Better to match the sensitivity of the driver than attempt to adapt an unsuited driver (unless you free your rear by using an active crossover, in which case, fun abounds!). Coupla options for you: there are pretty decent 96dB soft domes at www.apexjr.com for a whopping $15 a pair or so. Another choice would be the t26affneo from www.maxspeakers.com, it would be in the appropo sensitivity range.
I'm not happy with the sound on-axis of these, due to the front directivity controller, I'm thinking I need to try mine with that removed, but they're very good so long as you're not directly on axis.
*EDIT ON*
Of course, the soft domes don't subscribe to the controlled directivity we were discussing..... the T26affneo is a dome, but has a tiny horn/waveguide, so crossed somewhat lower (3.5k maybe?), should be quite a good match
*Edit off* |
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| Nuuk |
Badman, are you saying that the Fostex FT17H is not a good match with the 201's?
I am intending to use separate amps for the 201's and tweeters! :att'n: |
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| badman |
| The FT17H is a great tweeter but it's spec'd at 98.5dB sensitivity. But since you're biamping, that's easily solved, GO FOR IT! |
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| Nuuk |
| Hey guys - on a whim I have bought some Radio Shack bullet tweeters off Ebay. Am I correct in thinking that these are similar to the Fostex horn tweeters we have been discussing? :att'n: |
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| carlosfm |
Nuuk,
Just want to point out that you can't cross a supertweeter at ~6k with a first order crossover.
You must go above 10k.
I doubt that you need to cross that low with your fullranges, unless you cross the fullranges too.
Someone suggested you a pair of Seas tweeters (with low FS), and it was a good recomendation, based on what you want to do:att'n: |
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| Nuuk |
Thanks Carlos.
I plan to try a few options with the tweeters. At present, my cheapo silk domes sound quite good with a simple 1 uF cap (that's with the Goodmans 201's running without any filter).
The other options will involve cutting off the top end of the 201's at different frequencies (say 6, 8 and 10K) in which case I will beusing a second order active filter for the tweeters (and some delay).
The Seas was top of my list but the Fostex horn tweeter has a lot going for it so I'm going to try that first. Although, if the Radio Shack tweeters are close enough to the FostexF17H, I may not need to buy the latter!
If I can justify the outlay, I will try the Seas as well and compare the two. :) |
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| Nanook |
As far as I know (and I really don't know anything..) the RS supertweeters are as similar to the Fostex ones as the RS 40-1197s are to the Fostex 103's , which means they are pretty similar and most likely built by Fostex for RS (or perhaps "out of spec" Fosters sold off to RS rather than rework them?).
RS super tweeters |
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| Nuuk |
Thanks Nanook.
I also found that page. In fact that's what convinced me to bid on the ones that I bought. Hopefully they will be here this week and I can try them! :) |
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| badman |
| quote: | Originally posted by carlosfm
Nuuk,
Just want to point out that you can't cross a supertweeter at ~6k with a first order crossover.
You must go above 10k.
I doubt that you need to cross that low with your fullranges, unless you cross the fullranges too.
Someone suggested you a pair of Seas tweeters (with low FS), and it was a good recomendation, based on what you want to do:att'n: |
Depends on the tweeter and what volume level you require. While they'll have to handle more power and acoustic output with the less steep filter, that's a question for the person living with the speakers (a big strength of DIY is adapting your sound to your preferences). I generally like to XO them first order in that range, but it won't give the full acoustical output potential of the system (or power handling), which for a horn loaded 98.5dB tweet, for example, shouldn't really be an issue for rational home use.
But if you need to crank them up in a stadium, by all means, use MUCH steeper filters) |
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| Nuuk |
No stadium for me and I don't want to fall out with the neighbours either! ;)
Badman - do you know if the tweeters I bought on Ebay are the same (or similar) as the Fostex horn tweeters? |
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| carlosfm |
| quote: | Originally posted by badman
Depends on the tweeter and what volume level you require. While they'll have to handle more power and acoustic output with the less steep filter, that's a question for the person living with the speakers (a big strength of DIY is adapting your sound to your preferences). I generally like to XO them first order in that range, but it won't give the full acoustical output potential of the system (or power handling), which for a horn loaded 98.5dB tweet, for example, shouldn't really be an issue for rational home use. |
I really don't like spitty/distorted mids, that's what I mean. And it shows at low volume too.
To cross first order at 6k you need a really good, low FS tweeter.
You can't do this with a "supertweeter", or even with a normal tweeter.
I'm a fan of first order too, that's what I use (the Epos ES11 speakers). But that tweeter is exceptional. That tweeter can be crossed much lower (1st order) than what's used on the Epos and sound natural, I have tried it. |
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| mikelm |
Hi Nuuk,
You could try designing a cross-over with single cap at around 7khz but with a high pass second element that kicks in at a lower frequency.
This arrangement avoids the sharp "knee" that messes up the sound but still adds some extra LF filtering.
:) |
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| Nuuk |
| Thanks Mike, I will make a note of all these suggestions and hopefully get around to trying them all to see (or hear) which is the best arrangement! ;) |
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| badman |
Nuuk, I don't know if they're similar, though they look to be of the same fostex family. Only way to find out is to try them. I wish you good luck!
Carlos, the behavior of a tweeter is dependent upon many factors. I've played with many tweeters first order in this range, and with the appropriate sensitivity, and they do not cause spitty mids, unless overdriven, which will largely find its limits with the midwoof, in this instance. While your epos tweets may be nice, there's nothing about them, AFAIK, that makes them terribly unique or special, except that they're the tweeter that you're currently using. Cheers! |
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| carlosfm |
| quote: | Originally posted by badman
While your epos tweets may be nice, there's nothing about them, AFAIK, that makes them terribly unique or special, except that they're the tweeter that you're currently using. Cheers! |
Hey, I've heard and tested many tweeters.
These are very good, and can be crossed very low.
I have spares. I've opened them.
They are well made, and have a big back chamber, they work very well when crossed low, even 1st order.
Most others don't, IME.
But if your post above makes you happy, I'll let you be happy for a while. ;) |
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| baggins |
Crikey ,
Just read this thread ,I remember Coles tweeters from yonks back
when I built my first stereo with sn76013's,garrard sp25mk2 ,Acos
gp93/1 cartridge Ah brings back memories!! I couldnt aspire to them then and it looks like the same applies now! i forget the speakers they were probably something really naff like poly planars HaHa |
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| planet10 |
| quote: | Originally posted by Nuuk
do you know if I bought on Ebay are the same (or similar) as the Fostex horn tweeters? [/B] |
Those are the tweeters out of a pair of radio shack add on pods. They are a foster horn that should be very similar ro the FT17. They are excellent and you got the pair for an excellent price.
I almost mentioned these earlier in the thread.
dave |
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| planet10 |
| and another. This really is a cool tweeter. |
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| planet10 |
| factory spec sheet |
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| planet10 |
I don't have an impedance curve, but i have a pair i could measure if you wanted...
dave |
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| Nuuk |
| quote: | | Those are the tweeters out of a pair of radio shack add on pods. They are a foster horn that should be very similar ro the FT17. They are excellent and you got the pair for an excellent price. |
Thanks Dave, just what I wanted to hear! :) I even got the shipping charges waved because I gave the seller some advice on his own hi-fi.
If it's not too much trouble, I guess the impedance curve would be useful in planning a crossover! :scratch: |
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| Lionel |
| quote: | | I guess the impedance curve would be useful in planning a crossover! |
Not really.
You just need to find the optimum frequency to fit your full-range.
Only one cap will make you the simpliest and best first-order crossover you can imagine.
Good luck. |
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| Nuuk |
| quote: | Not really.
You just need to find the optimum frequency to fit your full-range.
Only one cap will make you the simpliest and best first-order crossover you can imagine. |
Thanks Lionel. So the impedance curve is for academic interest!
I'm going to use separate amps to match any difference in sensitivity! :att'n: |
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| mikelm |
| seems to me impedance is pretty central in X-over design |
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| Nuuk |
| quote: | | seems to me impedance is pretty central in X-over design |
Even when crossing over from 6K up Mike? |
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| badman |
| In the case of these horns, fortunately the impedance curves are pretty darned flat, as a rule. you're probably fine using the nominal value for an 8 ohm driver. |
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| mikelm |
well - if your happy with trial & error no problems... :-)
however for good educated guess you you need to work out the cap value whos capacitive reactance ( Xc ) equals the impedance of the device at the selected X-over frequency.
Xc = 1/ 2pi FC
where Xc = capacitive reactance
F = cross-over frequency
C = value of cap
so C = 1/ 2pi F Xc ( I think )
then you have to do the listening & ( measuring if possible ) ... :) |
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| Nuuk |
| quote: | | however for good educated guess you you need to work out the cap value whos capacitive reactance ( Xc ) equals the impedance of the device at the selected X-over frequency. |
I will probably test out the bulltet tweeters on the existing set-up using the same caps as I use for the silk-domes. Bit for the new baffles I will be using active crossovers for the tweeters so does this still apply? |
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| planet10 |
| quote: | Originally posted by Nuuk
So the impedance curve is for academic interest! |
Maybe. Maybe not. It gives you an idea for a starting point.
I choose caps that give me an XO about an octave above where i think it should be. Then keep adding parallel caps (i have a big stash of 0.1 uF for this) until the tweeter becomes a bit too noticable, then back off a bit. It will take a while of listening and it is by ear, but the curve gives you your starting point and shows if you have any little wrinkles to deal with.
The ballpark here is to start with 1 uF and work your way upwards (i'd guess you won't reach 3 uF) -- this is for an 8 ohm tweeter. Larger values if the actual impedance is lower, smaller if higher.
dave |
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| mikelm |
| quote: | Originally posted by Nuuk
I will probably test out the bulltet tweeters on the existing set-up using the same caps as I use for the silk-domes. Bit for the new baffles I will be using active crossovers for the tweeters so does this still apply? |
So you will connect the amp direct to the tweeters ? - I've often wondered about this - is it safe. Turn on thump etc. |
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| Nuuk |
| quote: | | So you will connect the amp direct to the tweeters ? - I've often wondered about this - is it safe. Turn on thump etc. |
I ran my active system for over two years with the amps connected directly to the drivers (woofer and tweeter). However, I did use Velleman speaker protection modules so the connection was not made until everything had 'settled down'.
Now I must make the decision whether I use protection again! (I will need to buy another module for a start). |
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| Lionel |
| quote: | | So the impedance curve is for academic interest! |
In this case YES !.
Watch the impedance curve of the FT17H :
FT17H
It is flat !!! Between 5 to 20 khz the impedance is equal to the its nominal value : 8 Ohms...
...and since you will use THIS value to calculate the value of your cap.
Just a question of common sens... :angel: |
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| Nuuk |
| quote: | In this case YES !.
Watch the impedance curve of the FT17H : |
That's good newsLionel but I think Dave was offering to see if the Radio Shack tweeters have the same impedance curve. :) |
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| planet10 |
| quote: | Originally posted by Nuuk
I think Dave was offering to see if the Radio Shack tweeters have the same impedance curve. :) |
Exactly. They are in their pods so i need to dissassemble to get past the XO.
The scale on the Fostex FT17 sheet is a bit deceptive. Very squashed scale & the impedance magnitude axis is logarythmic. Still pretty flat.
dave |
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| Nuuk |
OK chaps, the Radio Shack bullet tweeters are now playing in my open baffles and sound pretty good to me!
I have installed them with a 1 uF cap and no padding. I decided that the Goodmans 201's would be a close enough match in sensitivity and that appears to be the case.
The change in tonal balance is immediately discernable. After a listen to a few Jack Johnson tracks, I put on Roger Waters (Amused to Death) and with this CD the changes are even more apparent. All those little sound effects are moved further out into the room such that they surround the listening position even more than before.
After an hour of continuous listening I haven't heard anything that I dislike but I'll need to listen to many more recordings to find out if these are my 'final' tweeters. :) |
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