2-ways accuton bookshelf

[kevinlin1013]

I am ready to DIY a 2-ways bookshelf based on accuton drivers. I have ordered a pair of C158-8-085 mid-woofer but it seems there is very rare discussion of this driver for DIY.

The tweeter is considerated to use accuton C25 or C30 , Can I get some suggeston? If I want to cross at 2.5K for second-order , Does it a little over load for the C25?

If considering the Scan-Speak tweeter like ScanSpeak R2904/7000 , D2904/7100 , R3004/6620-00 , D3004-6620.....Will it get better proformance?

Asking for some suggestion for the driver selecting and cross-over point recommendation.

Thanks for everybody's help!

[crazyhub]

The main cone break-up of the C158 is near 4.1khz; a third harmonic distortion occurs near 1.4khz; so I would try to cross the two drivers in this area. Obviously the x-max of a C30 should better suit this Fx than a C25.
IMHO, SS tweeters or Accuton ones aren't a matter of performance but a matter of taste.

[kevinlin1013]

Originally Posted by crazyhub

The main cone break-up of the C158 is near 4.1khz; a third harmonic distortion occurs near 1.4khz; so I would try to cross the two drivers in this area. Obviously the x-max of a C30 should better suit this Fx than a C25.
IMHO, SS tweeters or Accuton ones aren't a matter of performance but a matter of taste.

Thank for your information. I have contacted the local driver dealer , they said:"It is very dangerous to crossover the ceramic tweeter below 3KHz by 2nd-order filter."

Is it real? Did someone have the experiment of the ceramic tweeter? Thanks !

[Godzilla]

lol about experimenting on such an expensive tweeter.

the accuton speakers i heard at shows in NYC all sounded really good.

[crazyhub]

A C30-6-023 has a linear excursion of +/- 1.1mm, a Fs of 570hz, is ferrofluid filled, is rated 120w power handling; Accuton recommand to cut it over 1800hz, saying nothing about the slope.
Regarding its x-max of 1.1mm, its Sd of 8.55cm² and impedance of 7.5 ohms at 1.5khz, it should theorically be able to give 109dbs / 1meter into free space (add 6dbs into half-space) at 1.5khz just before reaching its x-max. So 97dbs at 750hz (-12dbs), 85dbs at 375hz (-12dbs).
So this driver can theorically be cuted second order acoustic at 1.5khz if you project to use it half-space at max 115dbs / 1m; or still 2nd order at 2khz at max 120dbs; or still 2nd order at 2.5khz at max 124dbs. All these data are x-max related, not power compression. Nevertheless you see that the statement "It is very dangerous to crossover the ceramic tweeter below 3KHz by 2nd-order filter." isn't right in this case.
In its Humble Statement Tony Gee crosses a C30N-6-24 over at 2khz 12db/oct without any problem:
Humble Homemade Hifi

[kevinlin1013]

Originally Posted by Godzilla

lol about experimenting on such an expensive tweeter.

the accuton speakers i heard at shows in NYC all sounded really good.

It's really expensive drivers.
I really love the sound provided by the ceramic driver. I have heard Avalon/Lumenwhite/Marten Design/Kharma/Consensus Audio Speakers and love the sound. But they are expensive and too big for me now...

So I think to begin with a small two-ways monitor is a good idea.

[kevinlin1013]

Originally Posted by crazyhub

In its Humble Statement Tony Gee crosses a C30N-6-24 over at 2khz 12db/oct without any problem:
Humble Homemade Hifi

Thanks! Mr.crazyhub for providing such useful information and suggestions.

It is my first time to design a crossover circuit from the beginning. My previous speaker is Scan-Speak 9500+8545 and just used the circuit from the internet.

If I want to start with the crossover calculator which impedance should I use? From the chart of the driver to find the frequency that I want to use as crossover-point?

[sreten]

Originally Posted by kevinlin1013

Thanks! Mr.crazyhub for providing such useful information and suggestions.

It is my first time to design a crossover circuit from the beginning. My previous speaker is Scan-Speak 9500+8545 and just used the circuit from the internet.

If I want to start with the crossover calculator which impedance should I use? From the chart of the driver to find the frequency that I want to use as crossover-point?

Hi,

Don't even think about using a crossover calculator with such drivers,
or in fact any decent drivers. You need to do it properly as outlined
below. You needs published measurements of the drivers.

FRD Consortium tools guide

rgds, sreten.

http://sites.google.com/site/undefinition/diy
Zaph|Audio
RJB Audio Projects
Speaker Design Works
HTGuide Forum - A Guide to HTguide.com Completed Speaker Designs.
Humble Homemade Hifi
Click below to go to
Quarter Wavelength Loudspeaker Design
The Frugal-Horns Site -- High Performance, Low Cost DIY Horn Designs
Linkwitz Lab - Loudspeaker Design
Music and Design

[crazyhub]

kevinlin I fully agree with sreten statements; accuton drivers are such accurate drivers that they obligatory need an accurate design; otherwise you will never get a fraction of what they are capable of.

[kevinlin1013]

Thanks for the information and helps!

If I use a notch filter before the mid-woofer for dealing with the cone-breakup , Should I change the value of the capacitors/inductors(Crossover circuit) just because of the impedance it loads has been changed?(Because added the Notch filter)