what is the difference between these two tweeters?

As the topic suggests, what is the difference between the Sea 27TBFCG and the 27TAFCG. I can't really tell what the physical difference is. I was wanting to get the 27TBFCG based on the reviews that I had read (namely Zaph's), but the Canadian store I want to order from (Solen) only have the 27TAFCG. What would I be losing by going to these tweeters?
 
What would you lose? Hmmm...

... a letter shift? ;)

Checking out Seas' web site, it appears the BF has a lower resonant frequency (550 vs. 900) and a slightly lower impedence peak. If this isn't a problem with your project design then I wouldn't worry about it.

Seas products


The massive resonant peak at about 25k is what I would worry about. Even at that frequency, I have found that peaks like that tend to add a slight shrillness to the upper HF range and increases listening fatigue. YMMV of course...

Mark
 
Thanks hooha. I knew about the frequency response difference (forgot to mention that), but never thought that a 25Khz peak might have a negative effect on the sound. I think I'm going to go with the Seas 27TDFC instead. It seems to have a smoother response at the top end. Zaph's review says that it's actually brighter sounding than the TB. I don't mind a slight brightness as long as it isn't fatiguing.

Do you have any suggestions for other tweeters that I might want to look at hooha? The main criteria is <$50, and a crossover at 2khz or less, and beyond that, just general listening performance.

How's the 'Peg treating ya? That's where I'm from, I'm just out here for University.
 
Zaph's comment on brightness is interesting. It could be a result of the 25k peak adding sensation to those frequencies that are audible.

As far as other models go, I've been out of the scene for quite awhile (sorry to see Dynaudio drop out of DIY) so I'm not the best to recommend alternatives. In the past though, I've found Seas tweeters to be good value and solid performers. I wouldn't hesitate to go for the fabric dome version you selected. If you don't mind me asking, what is your planned design?

As far as the 'Peg goes, we're drowning in rain here. Time to drop the speaker project and start building an ark...

Mark
 

tktran

Disabled Account
2003-03-17 4:30 am
Perth
kram0.com
hooha,

I respectfully disagree. I doubt whether many people could hear above 20Khz. Despite what the SACD/DVD-A marketeers are trying to sell me, I listen to what the audiologists and physiologists have taught me: I am a young fella in my mid twenties and even at this age high frequency hearing loss has already occurred.

These days many tweeters have extension out to 30Khz or beyond. eg. ScanSpeak D2905/9x00 series. I tried to test my upper frequency hearing limit by playing a 25Khz tone at +10dB relative to my normal listening level. Perhaps you could try it and see if you can hear it?

IMHO too much emphasis is placed on the ultrasonic region when people think of "harshness". People see the big sharp ultrasonic spike and get scared off. But in relative terms what is happening below 10Khz is more important than what is happening between 10-20Khz, which is even more important to what is happening above 20Khz.

Sometimes one of the first things to investigate in speakers that are described as harsh is the crossover region, or whether there is sufficient baffle step compensation. I have heard several crossover designers comment that when fine-tuning filters, a significant difference in tonal balance can be heard with a change of as little as +/- 0.5dB in the 100Hz to 4Khz region. Of course, this is strongly related to the region where the ear is most sensitive. But above 10Khz these changes make a difference not to tonal balance or perceived treble, but to perceived "air", or "presence"

The 27TBFCG is extremly smooth under 20Khz. Subjectively the 27TBFCG is one of the smoothest softest tweeters I have ever heard. Objectively it is one of the best measuring tweeters available to DIYers, irrespective of price.

Sorry for my little rant, but it's all in the filter folks.
 
Your rant is greatly appreciated tktran because you actually backed it up with your experience and such.

The problem is that the 27TBFCG is unavailable to me, otherwise I would have just gone ahead and bought it I think. Do you have experience with the 27TAFCG? That's the one that I can purchase. Now I'm also considering the 27TDFC.

hooha, I'm buillding a variation of the Eros project. The scanspeak tweeter is too expensive for me, so that's why I'm trying to replace it with a lower cost, yet still high performing tweeter. From what I've read, the Seas line seems to fit the bill, it's just a matter of deciding on exactly which model.
 

tktran

Disabled Account
2003-03-17 4:30 am
Perth
kram0.com
adolphe,

sorry I have not tried the 27TAFCG, nor seen comparative measurements of this tweeter.

Tony Gee http://home.hetnet.nl/~geenius has used both in his DD8 MkI and MKII loudspeakers. Unfortunately the comparison is blurred because he has also used different woofers and crossovers. Tony compares the speakers but to make reliable comparisons between tweeter A vs tweeter B I think other variables need to be fixed.
 
tktran said:
hooha,

I respectfully disagree. I doubt whether many people could hear above 20Khz. Despite what the SACD/DVD-A marketeers are trying to sell me, I listen to what the audiologists and physiologists have taught me: I am a young fella in my mid twenties and even at this age high frequency hearing loss has already occurred.

These days many tweeters have extension out to 30Khz or beyond. eg. ScanSpeak D2905/9x00 series. I tried to test my upper frequency hearing limit by playing a 25Khz tone at +10dB relative to my normal listening level. Perhaps you could try it and see if you can hear it?

IMHO too much emphasis is placed on the ultrasonic region when people think of "harshness". People see the big sharp ultrasonic spike and get scared off. But in relative terms what is happening below 10Khz is more important than what is happening between 10-20Khz, which is even more important to what is happening above 20Khz.

[snip]

Sorry for my little rant, but it's all in the filter folks.

That's fine if you disagree. But before you close the door on this, do a sine or gated sweep of a metal dome tweeter you know exibits this resonant peak. Beyond 16-20k frequencies are a sensation to the ear. That sensation becomes more excited at the point the resonant frequency is hit. If your ear is sensitive to this sensation, it will contribute negative effects as you listen to the driver for long periods.

We learned this back in the 80's when I was designing for a major Canadian loudspeaker firm. As a result, none of the speaker lines we manufactured had metal domes, and that was why.

Mark
 

tktran

Disabled Account
2003-03-17 4:30 am
Perth
kram0.com
Hello hooha,

I will give this a try, and see if I can feel any sensations.

Suppose that this is an issue ie. if a metal dome tweeter has a resonance peak, would a notch filter ameliorate the problem?

It seems a shame to rule out metal domes in your speaker designs simply due of the resonance peak.

I believe Mark K will have soon have measurements of the 27TBFC/G posted on his website...
 
tktran said:
Hello hooha,

I will give this a try, and see if I can feel any sensations.

Suppose that this is an issue ie. if a metal dome tweeter has a resonance peak, would a notch filter ameliorate the problem?

It seems a shame to rule out metal domes in your speaker designs simply due of the resonance peak.

I believe Mark K will have soon have measurements of the 27TBFC/G posted on his website...

Heh, its been a lot of years since performing tests like that - I'm almost affraid to do it for fear of knowing just how much my hearing has deteriorated. :xeye:

I respect Seas for posting such information beyond the '20k sound barrier'. Many others do not. I suppose if you wanted to, you could use a trap to muffle that peak at the expense of adding more components to your crossover and increasing cost. At the time, we didn't have that luxury; for every $1 spent on R&D = ~$5-6 on the retail front. It was more economical to go with a design that didn't exibit that anomaly in the first place, and would be suitable to the masses.

Let us know the results of your test.

Mark
 
adolphe said:
For reference, I think I've decided to go with the Seas 27TDFC. It's sounds like another great tweeter, and I think for my uses (until I get more critically of my drivers) will be more than satisfactory by the sounds of it.


Adolphe, I'm sure you'll be more than happy with whatever model you chose. Good luck with your project! ;)

Mark
 
tktran said:
Hello hooha,

Suppose that this is an issue ie. if a metal dome tweeter has a resonance peak, would a notch filter ameliorate the problem?

It seems a shame to rule out metal domes in your speaker designs simply due of the resonance peak.

Out of band resonance peaks might also affect in-band sound because the peak amplifies distortion products; that's most apparent in the distortion curves for Seas metal cone woofers. Granted, out of band harmonic distortion won't be audible for tweeters, but intermodulation distortion could heterodyne back into the passband. It'd be fun to run some tests in my copious free time.

A notch filter would have little effect as far as I can tell, since this problem is after the electronics (unless your system is in the habit of emitting lots of ultrasonics, in which case that's the least of your problems).


Francois.