Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Multi-Way Conventional loudspeakers with crossovers

Earthworks Sigma 6.2 Monitors
Earthworks Sigma 6.2 Monitors
Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 12th March 2019, 05:02 AM   #1
ouimetnick is offline ouimetnick  United States
diyAudio Member
 
Join Date: May 2011
Location: Beverly, Massachusetts, USA
Send a message via AIM to ouimetnick Earthworks Sigma 6.2 Monitors
Default Earthworks Sigma 6.2 Monitors

I've finally come across a pair of these at a price I could afford. I've drawn the crossover out to the best of my ability. Can someone explain the woofer's crossover and why it has 3 inductors? It seems the tweeter has a simple resistor to lower the level, and a 6.8uF cap to block low frequencies.

The drive units are Vifa units. XT25TG30-04 for the tweeter & P17SJ-00 008 as the woofer. Nice sounding speakers, perhaps a little bright, I find it interesting that the resistor I've labeled R2 is 4.7Ω and 3.9Ω on the other crossover. Is this how they dial everything in to be exact and get them as matched pairs?

Thanks,
Nick
Attached Images
File Type: jpg IMG_2323 copy.jpg (995.1 KB, 218 views)
File Type: jpg IMG_2325 copy.jpg (824.8 KB, 207 views)
File Type: jpg IMG_2281 copy.jpg (612.9 KB, 201 views)
File Type: jpeg Sigma 6.2.jpeg (396.3 KB, 201 views)
  Reply With Quote
Old 12th March 2019, 07:45 AM   #2
celef is offline celef
diyAudio Member
 
Join Date: Nov 2012
Congrats, that is one cool looking speaker!!

I have never heard it but been a fan of the look ever since I read about it in stereophile in 2003.

Earthworks Sigma 6.2 loudspeaker | Stereophile.com

I have the drivers on the shelf, and I think the midwoofer is more like midrange, not much bass can come out. Can you tell some about the interior, about the damping.

Crossover is a first order circuit with two response corrections on the midwoofer.

I am glad to see your pics, thank you!
  Reply With Quote
Old 12th March 2019, 02:49 PM   #3
Lojzek is offline Lojzek  Croatia
diyAudio Member
 
Lojzek's Avatar
 
Join Date: Feb 2012
Location: Croatia
Howdy, is this original crossover boards, wiring, soldering job, everything?
  Reply With Quote
Old 12th March 2019, 05:41 PM   #4
celef is offline celef
diyAudio Member
 
Join Date: Nov 2012
i did a dirty simulation of the xo, there seems to be room for improvements
Attached Images
File Type: jpg grafer.jpg (102.6 KB, 130 views)
  Reply With Quote
Old 12th March 2019, 08:24 PM   #5
PeteMcK is offline PeteMcK
diyAudio Member
 
Join Date: Feb 2002
Location: Western Sydney
If the suckout filter C1,R3,L3 is really connected like that, it'll affect both drivers
__________________
Impedance varies with frequency, use impedance plots of your drivers and make crossover calculations using the actual impedance of the driver at the crossover frequency
  Reply With Quote
Old 12th March 2019, 11:26 PM   #6
EarlK is offline EarlK  Canada
diyAudio Member
 
Join Date: Mar 2006
Location: Toronto (GTA), Ontario
Quote:
Originally Posted by PeteMcK View Post
If the suckout filter C1,R3,L3 is really connected like that, it'll affect both drivers
That particluar LCR is just an impedance equalizer.

See the effect with it in circuit ( red line at bottom ) or out.

Earthworks Sigma 6.2 Monitors-earthworks-sigma-6-2_-png

Attached Images
File Type: png Earthworks Sigma 6.2_.PNG (63.9 KB, 114 views)
  Reply With Quote
Old 12th March 2019, 11:37 PM   #7
EarlK is offline EarlK  Canada
diyAudio Member
 
Join Date: Mar 2006
Location: Toronto (GTA), Ontario
It's a bit of a unique circuit ( so thanks for bringing forward ).

The other LCR ( bypassing L1 ) acts as a PEQ with a bit of boost ( centered around 4200 hz ) which is the frequency area where JohnA ( of Stereophile fame ) mentioned there is measurable off-axis "bloom" .

Anyways, with both drivers set for positive polarity I need to add 1/2" of offset depth to the tweeter to get the hi-mids ( above 1K ) to break the 85db thresh-hold .

OTOH, if I flip the tweeters polarity ( and go back to zero offset I get the following;

Earthworks Sigma 6.2 Monitors-earthworks-sigma-6-2_hf_flipped-polarity_-png

The peakiness seen at around 8K ( now ) more closely resembles Stereophiles measurements ( I think ).

Click the image to open in full size.

Makes me wonder, what's going on here.

Attached Images
File Type: png Earthworks Sigma 6.2_HF_flipped polarity_.PNG (63.7 KB, 112 views)
Attached Files
File Type: dxo EarthWorks Sigma 6.2.dxo (63.2 KB, 1 views)

Last edited by EarlK; 12th March 2019 at 11:41 PM.
  Reply With Quote
Old 13th March 2019, 12:04 AM   #8
ouimetnick is offline ouimetnick  United States
diyAudio Member
 
Join Date: May 2011
Location: Beverly, Massachusetts, USA
Send a message via AIM to ouimetnick Earthworks Sigma 6.2 Monitors
I drew the crossover components and wiring on the opposite side just in case I've made a mistake in my drawings. Can someone explain how it all comes together and works? I'm guessing the complex nature is due to the time coherent design?
Attached Images
File Type: jpg IMG_2345.jpg (755.1 KB, 14 views)
File Type: jpg IMG_2346.jpg (615.5 KB, 14 views)
  Reply With Quote
Old 13th March 2019, 12:55 AM   #9
EarlK is offline EarlK  Canada
diyAudio Member
 
Join Date: Mar 2006
Location: Toronto (GTA), Ontario
Quote:
Originally Posted by ouimetnick View Post
I drew the crossover components and wiring on the opposite side just in case I've made a mistake in my drawings. Can someone explain how it all comes together and works? I'm guessing the complex nature is due to the time coherent design?
Your drawings are accurate, you haven't made any mistakes.

I mentioned in my first two posts what the 2 LCR circuits do ( one is an impedance EQ, that flattens the overall load, which is accomplished by the 1mH coil that's in series with the 15uF cap and the 10 ohm resistor ) while the other provides a bit of lowQ FR boost ( for the woofer ) centered around 4200hz ( that's the LCR comprisings parts values of 0.47mH, 3.3uF + 39R ).

The other components ( "my" schematics L1 & C1 < or > 1mH & 6.8uF ) form a 6db per octave crossover that's centered around 3K.

The 4.7R resistor found in front of C1 attenuates the tweeter level to better match the woofer.

Earthworks Sigma 6.2 Monitors-earthworks-sigma-6-2_3k-crossover_-png

Attached Images
File Type: png Earthworks Sigma 6.2_3K Crossover_.PNG (20.4 KB, 109 views)
  Reply With Quote
Old 13th March 2019, 09:51 PM   #10
ouimetnick is offline ouimetnick  United States
diyAudio Member
 
Join Date: May 2011
Location: Beverly, Massachusetts, USA
Send a message via AIM to ouimetnick Earthworks Sigma 6.2 Monitors
Just some more photos showing the cabinet and the construction. Threaded metal inserts are used to secure the back panel on. The P17SJ-00s were broken in, measured and "matched" No labels on the tweeters, but they seem to replace them with XT25TG30-04 and they sound identical. Binding Posts are WBT 0765 (fully insulated) apparently they are $40 each

I bought a Hafler XL-600 from a guy who worked there, and as such, I was shown around the place (they have measurement rooms and lots of fancy stuff) and that's when I heard these speakers for the first time. They had a bunch of Denmark made XT25TG30-04 tweeters lying around for replacement purposes.

I've also heard from Eric Blackmer (son of the founder) and he stated the cabinets were a real chore to produce. They had to send a lot of cabinets back due to defects. The difficulty of production and the discontinuation of the P17SJ/P17WJ I think is what pushed them to discontinue it (just my guess)
Attached Images
File Type: jpg IMG_2348.jpg (769.7 KB, 27 views)
File Type: jpg IMG_2349.jpg (825.4 KB, 34 views)
File Type: jpg IMG_2350.jpg (1,020.6 KB, 30 views)
File Type: jpg IMG_2351.jpg (814.8 KB, 19 views)
File Type: jpg IMG_2353.jpg (1,006.6 KB, 20 views)
File Type: jpg IMG_2354.jpg (650.5 KB, 18 views)
File Type: jpg IMG_2355.jpg (772.0 KB, 18 views)
  Reply With Quote

Reply


Earthworks Sigma 6.2 MonitorsHide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Measurement microphone: EC8000 vs UMIK-1 vs Earthworks M23 stolbovoy Digital Line Level 6 12th November 2015 02:19 PM
DIY passive studio monitors + amp, mod cheap monitors? jdominicjackson Full Range 11 11th June 2014 05:29 AM
DEQX HDP-3 w/ Earthworks M23 Microphone , Jensen Balanced Output Board , and Digital hum4god Swap Meet 13 2nd March 2013 01:42 PM
FE 208 Sigma Puffin Full Range 30 12th November 2007 10:05 PM
What is better: Earthworks M30 or DPA4090 ? Web Wolf Multi-Way 2 12th May 2006 09:23 PM


New To Site? Need Help?

All times are GMT. The time now is 01:47 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Copyright ©1999-2019 diyAudio
Wiki