Also to add to it, anything to look for on the T/S specs, FR / Distortion / waterfall charts to determine exceptional drivers or to value pricey ones as to what makes them good.
JR mentioned something about the FR impedance relationship in the dayton WG tweeter - that looks similar to the SB WG tweeter that might indicate some issues in XO or sound signature, etc...
What I see is an interesting scalloped front plate chamber that I've not seen on other tweeters. The pole vent hole is quite large with respect to the pole piece. The poll piece stuffing looks like well shaped and trimmed wool felt. The glue dabs could indicate some type of filler piece in the pole vent.
I've wanted a pair after hearing these in the Spirit Winds.
The following is a paid advertisement for Scan Speak
The obvious bits are staples of a good linear motor. Extended pole piece and full copper sleeve.
In the pole piece you don't have a simple round hole but a more complex shape to break up any reflection that does make its way back to the diaphragm. On the outside is the area that goes neglected in many tweeters, the airspace behind the surround. Again, lots of airspace here and a complex shape to mitigate those single frequency resonant modes. All together you are trying to remove any back pressure / compression effects that create distortion. The 9900 also includes a nice big cast face plate with a mild waveguide that helps to reduce cabinet diffraction effects.
T/S parameters are pointless in a tweeter, however something can be learned from the impedance. Remember that a speaker is a transducer, and that means that it converts one type of energy to another, and it's a 2-way street. Not only does a speaker convert electrical energy to acoustic, but acoustic energy to electrical. All speakers are microphones, just poor ones for the most part. The microphonic effects are visualized in an impedance sweep.
Little blips and wiggles are indications of reflections or resonances. If you can take your own impedance measurement, try doing a sweep with and without your hand or a board in front of a tweeter. The higher sensitivity the driver, the more pronounced these impedance issues will be. If simple putting your hand in front of the driver has an effect, it should be clear that loading a driver in a horn or waveguide has a significant impact on the resulting impedance.
Low Q humps in the impedance sweep are indication of inadequate chamber stuffing or airspace. They are usually accompanied by a dip in the frequency response. Depending on the crossover frequency this may not be a huge problem and may work to your advantage for a passive crossover, however I would not expect to see such "issues" in top of the line products. A good example of this being more of an issue is the Dayton RST28, as you can see a clear bump at 2.2kHz and a dip in the frequency response as a result.
An example where this is less of an issue is the Scan D2608 (aka Peerless HDS 810921 ). In this driver the hump is less pronounced around 1.5kHz, and creates a low Q response. This is easy to work with a 1.8-2kHz crossover frequency and actually aids to avoid a bump in the rolloff due to the driver Fs.
When it comes to dips in tweeter response, also consider a typical baffle diffraction response, here's a 9" wide baffle.
As you can see, generally there is a bump at 1-1.5kHz followed by a dip around 2.3kHz. In the case of the RST28, this exacerbates the dip that already exists in the response, so the problem becomes worse when you install the tweeter on a baffle. The low Q response of the D2608 is much less of an issue here.
wow, thanks john and Decibel. I'll have to take some time and re-read it. Most just went over my head. Any other opinion or observation, please add in.
Also, is there something to glean from the T/S or FR/impedance sweep for woofers, other tan the obvious box modelling, low end extension, break up points? Like, if i am looking for a dedicated mid, is there something in the TS / FR / Impedance I can look out for? similarly for dedicated low end duty under say 300hz or subwoofer duty. anything to indicate a good overall woofer that goes low enough but can also be crossed higher. I assume all these have some trade off or the other that makes them good for a certain application, but best to be avoided for others.
PS, John, I have always like the spirit winds since i heard it - one of my favorite speakers.
Agreed, the sound doesn't always follow the specs, but at least the specs can give an early filter / indication of what it might be good at - the reality can be quite different (even in the specs and what the specs translate into sound).
What i want to try is the RAAL 70-20, but there doesn't seem to be any source for it... anyways i am not ready for a project with it, so it's sitting in my wishlist....
Usually the larger mids or woofers will have a small peak at about 1-2k in the impedance for the 5-7" driver, and lower to about 800-900 Hz in an 8" woofer, corresponding also to a dip or peak (depending) in the frequency response. These are surround resonance artifacts. Even the Satori 7" has a dip at 1.5k with the blip in the impedance.
The F6 blemish is lower at about 900/1k due to the larger frame. I notched out the peak and improved it immensely.
I had this in the Morel CAW634, and I found it lacking in that range for clarity. Some will say it's not audible, but I feel you can 'miss' something if you don't know what is not there. When I swapped in for the TSCW636 (which supposedly has a mild peak there at the same point) the lacking or loss was no longer a problem.
Anything such as these should be seen as energy storage, even if measuring a dip in FR. In a waterfall, that dip can form a ridge in the decay.
@DanP I always knew the ScanSpeak 9900 was one of the best, but you really see why when someone dismantles it.
This is one of the best 2 or 3 tweeters I've ever heard. Worth every penny IMO. I got a little nervous a while back that they would be discontinued and I bought a pair, but I haven't used them yet. The guys at Scan said the motor on the 9900 is the same as the 9700. The only difference is the mild WG faceplate, but it seems to make a pretty big difference in the sound quality.
@DanP When you compare the two side by side on paper, the 9900 shallow waveguide definitely makes a difference in the 2-4kHz range, that will result in an improvement in overall power response.
I was recently reminded that a few of the original CSS LD25X were made with nice big waveguides, any chance of those coming back?
@DanP When you compare the two side by side on paper, the 9900 shallow waveguide definitely makes a difference in the 2-4kHz range, that will result in an improvement in overall power response.
I was recently reminded that a few of the original CSS LD25X were made with nice big waveguides, any chance of those coming back?
Funny you should mention that - Kerry and I were just discussing that option. We're going to experiment with some WG profiles and then see if our supplier can produce them with the next large batch we order. It will be a ways out behind the new SDX15 and several kit variations, but it's in the works.
Hey Dan, if you do come out with a profile that you like could you please let know. I wold like to have it incorporated in the baffle. This can be an early test. The CDs ldx is next on my project list, but build is delayed this year, by a lot.
Hey Dan, if you do come out with a profile that you like could you please let know. I wold like to have it incorporated in the baffle. This can be an early test. The CDs ldx is next on my project list, but build is delayed this year, by a lot.
You got it Ani. The profile will be determined well before production starts, but still won't be for a while unless we get lucky on an early iteration.
Aside from some of the drivers, why does the DOTD recently look like it's from a random box of product that they found buried in a back corner of the warehouse?
What's the word on PartsConnexion? Their prices, at least on capacitors, are much better than PE. Their Jantzen superior 2.2uf are $13 while PE is $21. Their silvers are $3 cheaper than PE's superior. Shipping's not bad either.
Any comments on the Clarity PX series or the Mundorf MCap Classic?
Hi John,
Curt and I use Clarity PX everywhere except the tweeter and then use CSA. We're big fans of Clarity caps. The PX are excellent and the differences in sound quality "to my ears" between PX and CSA is not a lot but it is noticeable on high res systems/speakers. I'm a fan!
What's the word on PartsConnexion? Their prices, at least on capacitors, are much better than PE. Their Jantzen superior 2.2uf are $13 while PE is $21. Their silvers are $3 cheaper than PE's superior. Shipping's not bad either.
I ordered a bunch of caps last week that showed in stock on the website - promptly got an email saying everything I ordered was 8 - 10 weeks out. So I just canceled the order but only got 1/3 of my money back and then the next day get an email from Canada Post saying my package from them is on the way🤷♂️ - I'm interested to see what I get
Comments
JR mentioned something about the FR impedance relationship in the dayton WG tweeter - that looks similar to the SB WG tweeter that might indicate some issues in XO or sound signature, etc...
I've wanted a pair after hearing these in the Spirit Winds.
Also, is there something to glean from the T/S or FR/impedance sweep for woofers, other tan the obvious box modelling, low end extension, break up points? Like, if i am looking for a dedicated mid, is there something in the TS / FR / Impedance I can look out for? similarly for dedicated low end duty under say 300hz or subwoofer duty. anything to indicate a good overall woofer that goes low enough but can also be crossed higher. I assume all these have some trade off or the other that makes them good for a certain application, but best to be avoided for others.
PS, John, I have always like the spirit winds since i heard it - one of my favorite speakers.
While I find the specifications interesting, there's no predicting if the sound is worth the $ by specs alone.
What i want to try is the RAAL 70-20, but there doesn't seem to be any source for it... anyways i am not ready for a project with it, so it's sitting in my wishlist....
The F6 blemish is lower at about 900/1k due to the larger frame. I notched out the peak and improved it immensely.
I had this in the Morel CAW634, and I found it lacking in that range for clarity. Some will say it's not audible, but I feel you can 'miss' something if you don't know what is not there. When I swapped in for the TSCW636 (which supposedly has a mild peak there at the same point) the lacking or loss was no longer a problem.
Anything such as these should be seen as energy storage, even if measuring a dip in FR. In a waterfall, that dip can form a ridge in the decay.
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