coaxial

[adason]

hi gentlemen,

just want to point your attention to a nice speakers
I could not resist and purchased 12" coaxial sammi sound
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=299-766
after a week of playing on the floor without the box I put it in temporary enclosure
sound excelent, highly recommended!
/I will still work on crossover, horn tweeter is overpowering woofer, nothing attenuator can not cure/

 

[adason]

I tested the speakers with both solid state and tube amps, works perfectly with both, highly efficient
bass is deep, midrange just fine, hights crystal clear but more efficient than should...
handles plenty of power

 

[rdf]

Soooo tempting. I love the sound of coaxials, and that efficiency/price/performance ratio too. It took a bit to find but here's the frequency response:

 

[Cal Weldon]

I couldn't resist either and have a pair sitting in boxes. I am interested in your XO.

 

[bikehorn]

wow! interesting. I hadn't seen this before, now i need to find an excuse to build something around these...haha

 

[Inductor]

Hi all,

adason
where did you buy your speaker clamps? Can't we find the old style cast clamps from JBL style. Much better but where to buy?

good work rdf but where is the rest? freq. curves for LF Unit and HF Unit, xover freq. ...

 

[adason]

hi rdf
thanks for the frequency response
if I will have some time, I will measure fr response in my room for each unit individualy

looking at the fr response , it confirms my impressions, it is tilting upwards, it could use variable attenuator to make it more flat
I currently do not have any, but I will purchase one soon
than I will experiment with setting on attenuator, once happy, I will measure the attenuator and install resistors

listening to the speakers, bass is nice and deep, it sounds fine without the subwoofer
however, coaxials could be used as midranges/tweeters on top of big efficient subwoofer, that should yield better sound and higher power handling

maybe even open baffle for coaxial on top of subwoofer

possibilities are limitless

cal, I will certainly put inductor on woofer, currently its running straight, only one 3.3 uF cap for tweeter
I put 6 uF at first but that was way too much hights
crossover is somewhere between 3 to 5 kHz
far from final, but most importantly speakers are already sounding great

highly suitable for small power amps

Inductor, I do not understand what you mean by clamps
speakers are mounted temporarily from the front on the baffle by screws
speakers on the back have gold plated high quality push and insert wire connectors, separate for each tweeter and woofer

Inductor, the fr response is complete, for both units together

 

[Inductor]

This is a speaker clamp.

 

[adason]

oh, I see, now I perfectly understand
you were looking at my other speakers, the monstrous cervin vega
I got those 18" cervins with clamps

the coaxial does not need it

 

[rdf]

Sorry, that's all I found. From a Korean site:

http://www.soundhouse.co.kr/html/so...mallcode=0&keyfield=&key=&number=11502&page=1

 

[Inductor]

can we trust that?
I am not saying it's wrong...
I'm asking, from the graphic, how much is the dB's (SPL) and impedance peaks? can you read "Ohms" there?... or 97 dB's... thats the good questions when we buy blind. Nothing against... if you can measure parameters. Those specs are a good start, but as somebody posted before you can not trust all the manufacturers... "42" can be between 40 and 50. For an "inexpensive" set up, not accurate system, must be just fine...

 

[Inductor]

I PICTURE THIS EXEMPLE FROM THE NET... just for looks...

http://gallery.audioasylum.com/cgi/...on=&&moniker=Les Hudson&invite=&w=1544&h=1158

 

[adason]

hi Inductor,

I'm asking, from the graphic, how much is the dB's (SPL) and impedance peaks? can you read "Ohms" there?... or 97 dB's...

yes, that scale is not right, it is pretty obvious....but at least we get the idea of slightly rising frequency response, which is not that much of the problem

I am going to travel a lot next week, but I promise, once I come back, I will measure fr response myself, total, and each unit separately
it will be response in my room, in my closed enclosure it is currently in, it will not be in scale, and it will have no resistance plot

inspite of that it should be uselfull, especialy for me, for tweeking the crossover for flat response

ed

 

[adason]

that net picture is interesting
it looks like small PA or HT system someone put together
if you are only going to use coaxial from let say 100 Hz up, it needs only small box, plus hanles more power once liberated from deep bass

that would be one way to go

now I must go, too much work...

 

[badman]

Measurements?

Adason? We still getting your numbers on these?

Thanks!

 

[Cal Weldon]

Yes please. Mine are still gathering dust and need a good home.

 

[adason]

i am back from 10days trip to good old europe, i will do it over this weekend

 

[adason]

just as i promised, i just measured fr response of the speaker
my setup is behringer ecm8000 mike, proprietory (excelent) mic preamp and digital multimeter with dB scale
its in relative scale, not per watt/meter

i measured first the woofer alone
attached is the graph, there are good news and bad news, it only goes to about 50Hz down, and it has almost 10 dB breakup at 1.6kHz
good news is its very flat between 50 to 1000 Hz

 

[adason]

as a signal source i use technics sl-p1200 cd player and Stryke's Test CD, which has both sine wave and warble tones
i used warble
signal is amplified by technics se-9060, no preamp

however, at the previous settings, when i started to measure tweeter, that was too loud and i did not want to burn neither my ears not the tweeter
so i reduced the volume and remeasured both the woofer and tweeter, tweeter was measured with 20uF, 10uF and 3.5 uF capacitors (only 3.5 uF fr response is shown)

next picture is fr response for both drivers

 

[Inductor]

Looks good.
Does anybody know tweet Fs?
That's important to design the xover. You want to go after (higher) than. It does not show any peak though (@ 1600Hz). The woof you just cross a little before (1600) at around 1000/1200 to make the peak go flat or leave it as is to join the HF driver up a little (+2/3dB's) and pad it or not. That's the full X-Ray.