Cap Value Recommendation for a 2 way

x2turbo

Member
2010-04-25 3:43 pm
I'm going to build a clone of the Decware DM945 and am looking for recommendations for the 1st order xover cap. I'm going to use them with my Decware Taboo MKIII

I'm going to use the 8" Silver Flute woofer and The HiVi tweeter.

https://www.madisoundspeakerstore.com/approx-8-woofers/silver-flute-w20rc38-04-ohm-8-wool-cone/

https://www.madisoundspeakerstore.com/ribbon-tweeters/hi-vi-rt1c-a-isodynamic-tweeter-120mm-94db/

.8cuft box with a 3" x 7" port

Any suggestions would be appreciated.
Thanks
 

eriksquires

Member
2013-05-10 4:11 pm
Whoops! I just re-read your question. I just realized you are asking about a cap value, not a brand. Sorry.

Try the on-line crossover calculator from V-Cap.

However, that's just a simple answer. Do you really need a simple answer, or is this your first X-over and you don't know where to start?

Parts-Express' page on the same tweeter recommends a 2nd order high pass filter, not a first order.

Also, I totally don't buy Silver Flute's spec's. A resonant frequency of 31Hz for an 8"? Also, check out Madisound's recommended enclosures. The f3 for the cabinets they are suggesting don't go anywhere near SF's frequency chart. Be very careful.


Best,


Erik
 
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I'd start with the standard values of 1.5 uF - 2.2uF -2.7uF -3.3 uF

If 8 kHz Fcut is required, also 1 uF

Some resistors might be required if a sensitivity pull-down on the tweeter is

asked ( 1-2-3 Ω ), but probably not since the woofer is driven full-band.

The equalization provided by the low damping factor of the amplifier would make

baffle step compensation ( BSC ) in its own way, being the response Z dependant
 

giralfino

Member
2009-02-28 9:20 pm
These two drivers won't go together, plain and simple, even with a higher order crossover. A 8" will beam above 1.5-2KHz, and that tweeter should be crossed more than an octave above that. With that woofer you need a robust tweeter, like a RS28, Peerless HDS, Seas 27TBFC/G just to name a few, and a LR4 crossover. If you want to use the HiVi tweeter you need a mid in between.

Ralf

In general, first order electrical is only for a small bunch of carefully designed drivers.
 
These two drivers won't go together, plain and simple, even with a higher order crossover. A 8" will beam above 1.5-2KHz, and that tweeter should be crossed more than an octave above that. With that woofer you need a robust tweeter, like a RS28, Peerless HDS, Seas 27TBFC/G just to name a few, and a LR4 crossover. If you want to use the HiVi tweeter you need a mid in between.

Ralf

In general, first order electrical is only for a small bunch of carefully designed drivers.

+ 1
 
They are those two drivers as far as I know. Note that that review is entirely subjective, and like most loudspeaker manufacturers, Decware do not provide any measurements. They do claim there is silk in the cone -YMMV on that front. Whether the FR of the Silver Flute is 'smooth enough that no crossover is needed' (quoting from their site) rather depends on opinion since there is no technical definition / criteria laid down. The HiVi planar tweeter recommended XO will likely be specified on power-handling & HD figures. It's quite common to see a tweeter's rated power-handling given assuming a 2nd order Butterworth at some pre-defined frequency. That doesn't mean you're obligated to use it; it's just a guide and common-sense + experience comes into effect on that front since it is largely circumstance dependent.

What Decware appear to be doing with the 945 is in essence similar to what a lot of people do with larger FR drivers, capping off a supertweeter at XYZ frequency. So if you approach it from that angle / perspective, rather than that of a conventional multiway, it's not all that unusual & appears to be 'good enough' for their buyers. They may also be playing with phase -with the right cap value and polarity, it's possible they may get some destructive interference between the drivers in the 4KHz - 5KHz band that partly cancels out the elevated response at the top end of the Silver Flute's range. Ruler flat response? I very much doubt it, but they presumably had other priorities in mind. It's interesting how you can actually get a decent enough sound out of something that technically appears dodgy. Not invariable, and depends on your qualitative baseline, but I found that out the hard way with a speaker that technically 'shouldn't work' i.e. should sound appalling. In practice, it actually sounded rather good, despite the duff measured performance. Sometimes these things happen. Not often, but it's not unknown. Psychoacoustics can be a funny old thing.
 
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- Hi Everyone , I realize this is an Ancient Post but I wanted to chime in and say something about the subject - 🙂

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- If you Google the Decware SE84UFO Amplifier your can listen to all of the great video reviews, including Steve Guttenberg's - " The Audiophiliac" two videos on it ... - ( I know it's a strange name - lol ) ...


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--- and because of that , and Because of all of his Posts that he has made over the Years , And because of everyone else's opinion's about Steve who have actually Met him and Spent time with him . . . . I Believe His Posts and Descriptions in his Ads or Information pages on his Audio Equipment - !!!!!!!!!!!!!!!

- ( in this case his Speakers ) -

------- So when looking at the the Specs for the speaker drivers..... on the Surface from the specs may not Seem like it would Sound very good --- but Steve has been designing and Building speakers for over 25 years , and wouldn't put Speakers for Sale on his Audio Website that didn't sound great - when he has Many other different models of Speakers for Sale, and also he has access to selling many other brands as well , so if he puts them for sale it's logical to assume they Sound very good , and there is a Lot of Feedback on the different speaker models that he sells as well ....... and by all accounts almost everyone who has heard his speakers says they sound Great.

-- THANKS for taking the time to listen, and I know everyone has their own opinions on our Audio hobby , Everyone brings something to this great hobby of ours - but I hope you will wait to hear some of Decware's Amplifiers or Speakers before pronouncing that they can't work well , Steve makes great equipment at pretty reasonable prices - 🙂

Kind regards, Dean